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ChangeLog (358375B)

---

 Mbed TLS ChangeLog (Sorted per branch, date)
 
 = Mbed TLS 3.6.4 branch released 2025-06-30
 
 Features
    * Add the function mbedtls_ssl_export_keying_material() which allows the
      client and server to extract additional shared symmetric keys from an SSL
      session, according to the TLS-Exporter specification in RFC 8446 and 5705.
      This requires MBEDTLS_SSL_KEYING_MATERIAL_EXPORT to be defined in
      mbedtls_config.h.
 
 Security
    * Fix a buffer overread in mbedtls_lms_import_public_key() when the input is
      less than 3 bytes. Reported by Linh Le and Ngan Nguyen from Calif.
      CVE-2025-49601
    * Fix a vulnerability in LMS verification through which an adversary could
      get an invalid signature accepted if they could cause a hash accelerator
      to fail. Found and reported by Linh Le and Ngan Nguyen from Calif.
      CVE-2025-49600
    * On x86/amd64 platforms, with some compilers, when the library is
      compiled with support for both AESNI and software AES and AESNI is
      available in hardware, an adversary with fine control over which
      threads make progress in a multithreaded program could force software
      AES to be used for some time when the program starts. This could allow
      the adversary to conduct timing attacks and potentially recover the
      key. In particular, this attacker model may be possible against an SGX
      enclave.
      The same vulnerability affects GCM acceleration, which could allow
      a similarly powerful adversary to craft GCM forgeries.
      CVE-2025-52496
    * Fix possible use-after-free or double-free in code calling
      mbedtls_x509_string_to_names(). This was caused by the function calling
      mbedtls_asn1_free_named_data_list() on its head argument, while the
      documentation did no suggest it did, making it likely for callers relying
      on the documented behaviour to still hold pointers to memory blocks after
      they were free()d, resulting in high risk of use-after-free or double-free,
      with consequences ranging up to arbitrary code execution.
      In particular, the two sample programs x509/cert_write and x509/cert_req
      were affected (use-after-free if the san string contains more than one DN).
      Code that does not call mbedtls_string_to_names() directly is not affected.
      Found by Linh Le and Ngan Nguyen from Calif.
      CVE-2025-47917
    * Fix a bug in mbedtls_asn1_store_named_data() where it would sometimes leave
      an item in the output list in an inconsistent state with val.p == NULL but
      val.len > 0. This impacts applications that call this function directly,
      or indirectly via mbedtls_x509_string_to_names() or one of the
      mbedtls_x509write_{crt,csr}_set_{subject,issuer}_name() functions. The
      inconsistent state of the output could then cause a NULL dereference either
      inside the same call to mbedtls_x509_string_to_names(), or in subsequent
      users of the output structure, such as mbedtls_x509_write_names(). This
      only affects applications that create (as opposed to consume) X.509
      certificates, CSRs or CRLs, or that call mbedtls_asn1_store_named_data()
      directly. Found by Linh Le and Ngan Nguyen from Calif.
      CVE-2025-48965
    * Fix an integer underflow that could occur when parsing malformed PEM
      keys, which could be used by an attacker capable of feeding encrypted
      PEM keys to a user. This could cause a crash or information disclosure.
      Found and reported by Linh Le and Ngan Nguyen from Calif.
      CVE-2025-52497
    * Fix a timing side channel in the implementation of PKCS#7 padding
      which would allow an attacker who can request decryption of arbitrary
      ciphertexts to recover the plaintext through a timing oracle attack.
      Reported by Ka Lok Wu from Stony Brook University and Doria Tang from
      The Chinese University of Hong Kong.
      CVE-2025-49087
 
 Bugfix
    * Fix failures of PSA multipart or interruptible operations when the
      library or the application is built with a compiler where
      "union foo x = {0}" does not initialize non-default members of the
      union, such as GCC 15 and some versions of Clang 18. This affected MAC
      multipart operations, MAC-based key derivation operations, interruptible
      signature, interruptible verification, and potentially other operations
      when using third-party drivers. This also affected one-shot MAC
      operations using the built-in implementation. Fixes #9814.
    * On entry to PSA driver entry points that set up a multipart operation
      ("xxx_setup"), the operation object is supposed to be all-bits-zero.
      This was sometimes not the case when an operation object is reused,
      or with compilers where "union foo x = {0}" does not initialize
      non-default members of the union. The PSA core now ensures that this
      guarantee is met in all cases. Fixes #9975.
    * Resolved build issue with C++ projects using Mbed TLS 3.6 when compiling
      with the MSVC toolset v142 and earlier. Fixes mbedtls issue #7087.
    * Silence spurious -Wunterminated-string-initialization warnings introduced
      by GCC 15. Fixes #9944.
    * Fix a sloppy check in LMS public key import, which could lead to accepting
      keys with a different LMS or LM-OTS types on some platforms. Specifically,
      this could happen on platforms where enum types are smaller than 32 bits
      and compiler optimization is enabled. Found and reported by Linh Le and
      Ngan Nguyen from Calif.
    * Fix a race condition on x86/amd64 platforms in AESNI support detection
      that could lead to using software AES in some threads at the very
      beginning of a multithreaded program. Reported by Solar Designer.
      Fixes #9840.
    * Fix mbedtls_base64_decode() on inputs that did not have the correct
      number of trailing equal signs, or had 4*k+1 digits. They were accepted
      as long as they had at most two trailing equal signs. They are now
      rejected. Furthermore, before, on inputs with too few equal signs, the
      function reported the correct size in *olen when it returned
      MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL, but truncated the output to the
      last multiple of 3 bytes.
    * When calling mbedtls_asn1_write_raw_buffer() with NULL, 0 as the last two
      arguments, undefined behaviour would be triggered, in the form of a call to
      memcpy(..., NULL, 0). This was harmless in practice, but could trigger
      complains from sanitizers or static analyzers.
 
 Changes
    * The function mbedtls_x509_string_to_names() now requires its head argument
      to point to NULL on entry. This makes it likely that existing risky uses of
      this function (see the entry in the Security section) will be detected and
      fixed.
 
 = Mbed TLS 3.6.3 branch released 2025-03-24
 
 Default behavior changes
    * In TLS clients, if mbedtls_ssl_set_hostname() has not been called,
      mbedtls_ssl_handshake() now fails with
      MBEDTLS_ERR_SSL_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
      if certificate-based authentication of the server is attempted.
      This is because authenticating a server without knowing what name
      to expect is usually insecure. To restore the old behavior, either
      call mbedtls_ssl_set_hostname() with NULL as the hostname, or
      enable the new compile-time option
      MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME.
 
 Features
    * Added new configuration option MBEDTLS_PSA_STATIC_KEY_SLOTS, which
      uses static storage for keys, enabling malloc-less use of key slots.
      The size of each buffer is given by the option
      MBEDTLS_PSA_STATIC_KEY_SLOT_BUFFER_SIZE. By default it accommodates the
      largest PSA key enabled in the build.
    * MD module can now perform PSA dispatching also when
      `MBEDTLS_PSA_CRYPTO_CLIENT && !MBEDTLS_PSA_CRYPTO_C`, even though this
      configuration is not officially supported. This requires that a
      PSA Crypto provider library which:
      * supports the required `PSA_WANT_ALG_xxx` and
      * implements `psa_can_do_hash()` on the client interface
      is linked against Mbed TLS and that `psa_crypto_init()` is called before
      performing any PSA call.
 
 Security
    * Note that TLS clients should generally call mbedtls_ssl_set_hostname()
      if they use certificate authentication (i.e. not pre-shared keys).
      Otherwise, in many scenarios, the server could be impersonated.
      The library will now prevent the handshake and return
      MBEDTLS_ERR_SSL_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
      if mbedtls_ssl_set_hostname() has not been called.
      Reported by Daniel Stenberg.
      CVE-2025-27809
    * Zeroize a temporary heap buffer used in psa_key_derivation_output_key()
      when deriving an ECC key pair.
    * Zeroize temporary heap buffers used in PSA operations.
    * Fix a vulnerability in the TLS 1.2 handshake. If memory allocation failed
      or there was a cryptographic hardware failure when calculating the
      Finished message, it could be calculated incorrectly. This would break
      the security guarantees of the TLS handshake.
      CVE-2025-27810
 
 Bugfix
    * When MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE is disabled, work with
      peers that have middlebox compatibility enabled, as long as no
      problematic middlebox is in the way. Fixes #9551.
    * Fix invalid JSON schemas for driver descriptions used by
      generate_driver_wrappers.py.
    * Use 'mbedtls_net_close' instead of 'close' in 'mbedtls_net_bind'
      and 'mbedtls_net_connect' to prevent possible double close fd
      problems. Fixes #9711.
    * Fix undefined behavior in some cases when mbedtls_psa_raw_to_der() or
      mbedtls_psa_der_to_raw() is called with bits=0.
    * Fix compilation on MS-DOS DJGPP. Fixes #9813.
    * Fix missing constraints on the AES-NI inline assembly which is used on
      GCC-like compilers when building AES for generic x86_64 targets. This
      may have resulted in incorrect code with some compilers, depending on
      optimizations. Fixes #9819.
    * Support re-assembly of fragmented handshake messages in TLS (both
      1.2 and 1.3). The lack of support was causing handshake failures with
      some servers, especially with TLS 1.3 in practice. There are a few
      limitations, notably a fragmented ClientHello is only supported when
      TLS 1.3 support is enabled. See the documentation of
      mbedtls_ssl_handshake() for details.
    * Fix definition of MBEDTLS_PRINTF_SIZET to prevent runtime crashes that
      occurred whenever SSL debugging was enabled on a copy of Mbed TLS built
      with Visual Studio 2013 or MinGW.
      Fixes #10017.
    * Remove Everest Visual Studio 2010 compatibility headers, which could
      shadow standard CRT headers inttypes.h and stdbool.h with incomplete
      implementatios if placed on the include path, eg. when building Mbed TLS
      with the .sln file shipped with the project.
    * Fix issue where psa_key_derivation_input_integer() is not detecting
      bad state after an operation has been aborted.
 
 Changes
    * Improve performance of PSA key generation with ECC keys: it no longer
      computes the public key (which was immediately discarded). Fixes #9732.
 
 = Mbed TLS 3.6.2 branch released 2024-10-14
 
 Security
    * Fix a buffer underrun in mbedtls_pk_write_key_der() when
      called on an opaque key, MBEDTLS_USE_PSA_CRYPTO is enabled,
      and the output buffer is smaller than the actual output.
      Fix a related buffer underrun in mbedtls_pk_write_key_pem()
      when called on an opaque RSA key, MBEDTLS_USE_PSA_CRYPTO is enabled
      and MBEDTLS_MPI_MAX_SIZE is smaller than needed for a 4096-bit RSA key.
      CVE-2024-49195
 
 = Mbed TLS 3.6.1 branch released 2024-08-30
 
 API changes
    * The experimental functions psa_generate_key_ext() and
      psa_key_derivation_output_key_ext() are no longer declared when compiling
      in C++. This resolves a build failure under C++ compilers that do not
      support flexible array members (a C99 feature not adopted by C++).
      Fixes #9020.
 
 Default behavior changes
    * In a PSA-client-only build (i.e. MBEDTLS_PSA_CRYPTO_CLIENT &&
      !MBEDTLS_PSA_CRYPTO_C), do not automatically enable local crypto when the
      corresponding PSA mechanism is enabled, since the server provides the
      crypto. Fixes #9126.
    * A TLS handshake may now call psa_crypto_init() if TLS 1.3 is enabled.
      This can happen even if TLS 1.3 is offered but eventually not selected
      in the protocol version negotiation.
    * By default, the handling of TLS 1.3 tickets by the Mbed TLS client is now
      disabled at runtime. Applications that were using TLS 1.3 tickets
      signalled by MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET return values now
      need to enable the handling of TLS 1.3 tickets through the new
      mbedtls_ssl_conf_tls13_enable_signal_new_session_tickets() API.
 
 New deprecations
    * The experimental functions psa_generate_key_ext() and
      psa_key_derivation_output_key_ext() are deprecated in favor of
      psa_generate_key_custom() and psa_key_derivation_output_key_custom().
      They have almost exactly the same interface, but the variable-length
      data is passed in a separate parameter instead of a flexible array
      member.
    * The following cryptographic mechanisms are planned to be removed
      in Mbed TLS 4.0:
      - DES (including 3DES).
      - PKCS#1v1.5 encryption/decryption (RSAES-PKCS1-v1_5).
        (OAEP, PSS, and PKCS#1v1.5 signature are staying.)
      - Finite-field Diffie-Hellman with custom groups.
        (RFC 7919 groups remain supported.)
      - Elliptic curves of size 225 bits or less.
    * The following cipher suites are planned to be removed from (D)TLS 1.2
      in Mbed TLS 4.0:
      - TLS_RSA_* (including TLS_RSA_PSK_*), i.e. cipher suites using
        RSA decryption.
        (RSA signatures, i.e. TLS_ECDHE_RSA_*, are staying.)
      - TLS_ECDH_*, i.e. cipher suites using static ECDH.
        (Ephemeral ECDH, i.e. TLS_ECDHE_*, is staying.)
      - TLS_DHE_*, i.e. cipher suites using finite-field Diffie-Hellman.
        (Ephemeral ECDH, i.e. TLS_ECDHE_*, is staying.)
      - TLS_*CBC*, i.e. all cipher suites using CBC.
    * The following low-level application interfaces are planned to be removed
      from the public API in Mbed TLS 4.0:
      - Hashes: hkdf.h, md5.h, ripemd160.h, sha1.h, sha3.h, sha256.h, sha512.h;
      - Random generation: ctr_drbg.h, hmac_drbg.h, entropy.h;
      - Ciphers and modes: aes.h, aria.h, camellia.h, chacha20.h, chachapoly.h,
        cipher.h, cmac.h, gcm.h, poly1305.h;
      - Private key encryption mechanisms: pkcs5.h, pkcs12.h.
      - Asymmetric cryptography: bignum.h, dhm.h, ecdh.h, ecdsa.h, ecjpake.h,
        ecp.h, rsa.h.
      The cryptographic mechanisms remain present, but they will only be
      accessible via the PSA API (psa_xxx functions introduced gradually
      starting with Mbed TLS 2.17) and, where relevant, `pk.h`.
      For guidance on migrating application code to the PSA API, please consult
      the PSA transition guide (docs/psa-transition.md).
    * The following integration interfaces are planned to be removed
      in Mbed TLS 4.0:
      - MBEDTLS_xxx_ALT replacement of cryptographic modules and functions.
        Use PSA transparent drivers instead.
      - MBEDTLS_PK_RSA_ALT and MBEDTLS_PSA_CRYPTO_SE_C.
        Use PSA opaque drivers instead.
 
 Features
    * When the new compilation option MBEDTLS_PSA_KEY_STORE_DYNAMIC is enabled,
      the number of volatile PSA keys is virtually unlimited, at the expense
      of increased code size. This option is off by default, but enabled in
      the default mbedtls_config.h. Fixes #9216.
 
 Security
    * Unlike previously documented, enabling MBEDTLS_PSA_HMAC_DRBG_MD_TYPE does
      not cause the PSA subsystem to use HMAC_DRBG: it uses HMAC_DRBG only when
      MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG and MBEDTLS_CTR_DRBG_C are disabled.
      CVE-2024-45157
    * Fix a stack buffer overflow in mbedtls_ecdsa_der_to_raw() and
      mbedtls_ecdsa_raw_to_der() when the bits parameter is larger than the
      largest supported curve. In some configurations with PSA disabled,
      all values of bits are affected. This never happens in internal library
      calls, but can affect applications that call these functions directly.
      CVE-2024-45158
    * With TLS 1.3, when a server enables optional authentication of the
      client, if the client-provided certificate does not have appropriate values
      in keyUsage or extKeyUsage extensions, then the return value of
      mbedtls_ssl_get_verify_result() would incorrectly have the
      MBEDTLS_X509_BADCERT_KEY_USAGE and MBEDTLS_X509_BADCERT_EXT_KEY_USAGE bits
      clear. As a result, an attacker that had a certificate valid for uses other
      than TLS client authentication could be able to use it for TLS client
      authentication anyway. Only TLS 1.3 servers were affected, and only with
      optional authentication (required would abort the handshake with a fatal
      alert).
      CVE-2024-45159
 
 Bugfix
    * Fix TLS 1.3 client build and runtime when support for session tickets is
      disabled (MBEDTLS_SSL_SESSION_TICKETS configuration option). Fixes #6395.
    * Fix compilation error when memcpy() is a function-like macros. Fixes #8994.
    * MBEDTLS_ASN1_PARSE_C and MBEDTLS_ASN1_WRITE_C are now automatically enabled
      as soon as MBEDTLS_RSA_C is enabled. Fixes #9041.
    * Fix undefined behaviour (incrementing a NULL pointer by zero length) when
      passing in zero length additional data to multipart AEAD.
    * Fix rare concurrent access bug where attempting to operate on a
      non-existent key while concurrently creating a new key could potentially
      corrupt the key store.
    * Fix error handling when creating a key in a dynamic secure element
      (feature enabled by MBEDTLS_PSA_CRYPTO_SE_C). In a low memory condition,
      the creation could return PSA_SUCCESS but using or destroying the key
      would not work. Fixes #8537.
    * Fix issue of redefinition warning messages for _GNU_SOURCE in
      entropy_poll.c and sha_256.c. There was a build warning during
      building for linux platform.
      Resolves #9026
    * Fix a compilation warning in pk.c when PSA is enabled and RSA is disabled.
    * Fix the build when MBEDTLS_PSA_CRYPTO_CONFIG is enabled and the built-in
      CMAC is enabled, but no built-in unauthenticated cipher is enabled.
      Fixes #9209.
    * Fix redefinition warnings when SECP192R1 and/or SECP192K1 are disabled.
      Fixes #9029.
    * Fix psa_cipher_decrypt() with CCM* rejecting messages less than 3 bytes
      long. Credit to Cryptofuzz. Fixes #9314.
    * Fix interference between PSA volatile keys and built-in keys
      when MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS is enabled and
      MBEDTLS_PSA_KEY_SLOT_COUNT is more than 4096.
    * Document and enforce the limitation of mbedtls_psa_register_se_key()
      to persistent keys. Resolves #9253.
    * Fix Clang compilation error when MBEDTLS_USE_PSA_CRYPTO is enabled
      but MBEDTLS_DHM_C is disabled. Reported by Michael Schuster in #9188.
    * Fix server mode only build when MBEDTLS_SSL_SRV_C is enabled but
      MBEDTLS_SSL_CLI_C is disabled. Reported by M-Bab on GitHub in #9186.
    * When MBEDTLS_PSA_CRYPTO_C was disabled and MBEDTLS_ECDSA_C enabled,
      some code was defining 0-size arrays, resulting in compilation errors.
      Fixed by disabling the offending code in configurations without PSA
      Crypto, where it never worked. Fixes #9311.
    * Fix unintended performance regression when using short RSA public keys.
      Fixes #9232.
    * Fixes an issue where some TLS 1.2 clients could not connect to an
      Mbed TLS 3.6.0 server, due to incorrect handling of
      legacy_compression_methods in the ClientHello.
      Fixes #8995, #9243.
    * Fix TLS connections failing when the handshake selects TLS 1.3
      in an application that does not call psa_crypto_init().
      Fixes #9072.
    * Fix TLS connection failure in applications using an Mbed TLS client in
      the default configuration connecting to a TLS 1.3 server sending tickets.
      See the documentation of
      mbedtls_ssl_conf_tls13_enable_signal_new_session_tickets() for more
      information.
      Fixes #8749.
    * Fix a memory leak that could occur when failing to process an RSA
      key through some PSA functions due to low memory conditions.
    * Fixed a regression introduced in 3.6.0 where the CA callback set with
      mbedtls_ssl_conf_ca_cb() would stop working when connections were
      upgraded to TLS 1.3. Fixed by adding support for the CA callback with TLS
      1.3.
    * Fixed a regression introduced in 3.6.0 where clients that relied on
      optional/none authentication mode, by calling mbedtls_ssl_conf_authmode()
      with MBEDTLS_SSL_VERIFY_OPTIONAL or MBEDTLS_SSL_VERIFY_NONE, would stop
      working when connections were upgraded to TLS 1.3. Fixed by adding
      support for optional/none with TLS 1.3 as well. Note that the TLS 1.3
      standard makes server authentication mandatory; users are advised not to
      use authmode none, and to carefully check the results when using optional
      mode.
    * Fixed a regression introduced in 3.6.0 where context-specific certificate
      verify callbacks, set with mbedtls_ssl_set_verify() as opposed to
      mbedtls_ssl_conf_verify(), would stop working when connections were
      upgraded to TLS 1.3. Fixed by adding support for context-specific verify
      callback in TLS 1.3.
 
 Changes
    * Warn if mbedtls/check_config.h is included manually, as this can
      lead to spurious errors. Error if a *adjust*.h header is included
      manually, as this can lead to silently inconsistent configurations,
      potentially resulting in buffer overflows.
      When migrating from Mbed TLS 2.x, if you had a custom config.h that
      included check_config.h, remove this inclusion from the Mbed TLS 3.x
      configuration file (renamed to mbedtls_config.h). This change was made
      in Mbed TLS 3.0, but was not announced in a changelog entry at the time.
 
 = Mbed TLS 3.6.0 branch released 2024-03-28
 
 API changes
    * Remove `tls13_` in mbedtls_ssl_tls13_conf_early_data() and
      mbedtls_ssl_tls13_conf_max_early_data_size() API names. Early data
      feature may not be TLS 1.3 specific in the future. Fixes #6909.
 
 Default behavior changes
    * psa_import_key() now only accepts RSA keys in the PSA standard formats.
      The undocumented ability to import other formats (PKCS#8, SubjectPublicKey,
      PEM) accepted by the pkparse module has been removed. Applications that
      need these formats can call mbedtls_pk_parse_{public,}key() followed by
      mbedtls_pk_import_into_psa().
 
 Requirement changes
    * Drop support for Visual Studio 2013 and 2015, and Arm Compiler 5.
 
 New deprecations
    * Rename the MBEDTLS_SHA256_USE_A64_CRYPTO_xxx config options to
      MBEDTLS_SHA256_USE_ARMV8_A_CRYPTO_xxx. The old names may still
      be used, but are deprecated.
    * In the PSA API, domain parameters are no longer used for anything.
      They are deprecated and will be removed in a future version of the
      library.
    * mbedtls_ecp_write_key() is deprecated in favor of
      mbedtls_ecp_write_key_ext().
 
 Removals
    * In the PSA API, the experimental way to encode the public exponent of
      an RSA key as a domain parameter is no longer supported. Use
      psa_generate_key_ext() instead.
    * Temporary function mbedtls_pk_wrap_as_opaque() is removed. To mimic the
      same behavior mbedtls_pk_get_psa_attributes() and
      mbedtls_pk_import_into_psa() can be used to import a PK key into PSA,
      while mbedtls_pk_setup_opaque() can be used to wrap a PSA key into a opaque
      PK context.
 
 Features
    * Added an example program showing how to hash with the PSA API.
    * Support Armv8-A Crypto Extension acceleration for SHA-256
      when compiling for Thumb (T32) or 32-bit Arm (A32).
    * AES-NI is now supported in Windows builds with clang and clang-cl.
      Resolves #8372.
    * Add new mbedtls_x509_csr_parse_der_with_ext_cb() routine which allows
      parsing unsupported certificate extensions via user provided callback.
    * Enable the new option MBEDTLS_BLOCK_CIPHER_NO_DECRYPT to omit
      the decryption direction of block ciphers (AES, ARIA, Camellia).
      This affects both the low-level modules and the high-level APIs
      (the cipher and PSA interfaces). This option is incompatible with modes
      that use the decryption direction (ECB in PSA, CBC, XTS, KW) and with DES.
    * Support use of Armv8-A Cryptographic Extensions for hardware acclerated
      AES when compiling for Thumb (T32) or 32-bit Arm (A32).
    * If a cipher or AEAD mechanism has a PSA driver, you can now build the
      library without the corresponding built-in implementation. Generally
      speaking that requires both the key type and algorithm to be accelerated
      or they'll both be built in. However, for CCM and GCM the built-in
      implementation is able to take advantage of a driver that only
      accelerates the key type (that is, the block cipher primitive). See
      docs/driver-only-builds.md for full details and current limitations.
    * The CTR_DRBG module will now use AES from a PSA driver if MBEDTLS_AES_C is
      disabled. This requires PSA_WANT_ALG_ECB_NO_PADDING in addition to
      MBEDTLS_PSA_CRYPTO_C and PSA_WANT_KEY_TYPE_AES.
    * Fewer modules depend on MBEDTLS_CIPHER_C, making it possible to save code
      size by disabling it in more circumstances. In particular, the CCM and
      GCM modules no longer depend on MBEDTLS_CIPHER_C. Also,
      MBEDTLS_PSA_CRYPTO can now be enabled without MBEDTLS_CIPHER_C if all
      unauthenticated (non-AEAD) ciphers are disabled, or if they're all
      fully provided by drivers. See docs/driver-only-builds.md for full
      details and current limitations; in particular, NIST_KW and PKCS5/PKCS12
      decryption still unconditionally depend on MBEDTLS_CIPHER_C.
    * Add support for record size limit extension as defined by RFC 8449
      and configured with MBEDTLS_SSL_RECORD_SIZE_LIMIT.
      Application data sent and received will be fragmented according to
      Record size limits negotiated during handshake.
    * Improve performance of AES-GCM, AES-CTR and CTR-DRBG when
      hardware accelerated AES is not present (around 13-23% on 64-bit Arm).
    * Add functions mbedtls_ecc_group_to_psa() and mbedtls_ecc_group_from_psa()
      to convert between Mbed TLS and PSA curve identifiers.
    * Add utility functions to manipulate mbedtls_ecp_keypair objects, filling
      gaps made by making its fields private: mbedtls_ecp_set_public_key(),
      mbedtls_ecp_write_public_key(), mbedtls_ecp_keypair_calc_public(),
      mbedtls_ecp_keypair_get_group_id(). Fixes #5017, #5441, #8367, #8652.
    * Add functions mbedtls_md_psa_alg_from_type() and
      mbedtls_md_type_from_psa_alg() to convert between mbedtls_md_type_t and
      psa_algorithm_t.
    * Add partial platform support for z/OS.
    * Improve performance for gcc (versions older than 9.3.0) and IAR.
    * Add functions mbedtls_ecdsa_raw_to_der() and mbedtls_ecdsa_der_to_raw() to
      convert ECDSA signatures between raw and DER (ASN.1) formats.
    * Add support for using AES-CBC 128, 192, and 256 bit schemes
      with PKCS#5 PBES2. Keys encrypted this way can now be parsed by PK parse.
    * The new function mbedtls_rsa_get_bitlen() returns the length of the modulus
      in bits, i.e. the key size for an RSA key.
    * Add pc files for pkg-config, e.g.:
      pkg-config --cflags --libs (mbedtls|mbedcrypto|mbedx509)
    * Add getter (mbedtls_ssl_session_get_ticket_creation_time()) to access
      `mbedtls_ssl_session.ticket_creation_time`.
    * The new functions mbedtls_pk_get_psa_attributes() and
      mbedtls_pk_import_into_psa() provide a uniform way to create a PSA
      key from a PK key.
    * The benchmark program now reports times for both ephemeral and static
      ECDH in all ECDH configurations.
    * Add support for 8-bit GCM tables for Shoup's algorithm to speedup GCM
      operations when hardware accelerated AES is not present. Improves
      performance by around 30% on 64-bit Intel; 125% on Armv7-M.
    * The new function psa_generate_key_ext() allows generating an RSA
      key pair with a custom public exponent.
    * The new function mbedtls_ecp_write_key_ext() is similar to
      mbedtls_ecp_write_key(), but can be used without separately calculating
      the output length.
    * Add new accessor to expose the private group id member of
      `mbedtls_ecdh_context` structure.
    * Add new accessor to expose the `MBEDTLS_PRIVATE(ca_istrue)` member of
      `mbedtls_x509_crt` structure. This requires setting
      the MBEDTLS_X509_EXT_BASIC_CONSTRAINTS bit in the certificate's
      ext_types field.
    * mbedtls_psa_get_random() is always available as soon as
      MBEDTLS_PSA_CRYPTO_CLIENT is enabled at build time and psa_crypto_init() is
      called at runtime. This together with MBEDTLS_PSA_RANDOM_STATE can be
      used as random number generator function (f_rng) and context (p_rng) in
      legacy functions.
    * The new functions mbedtls_pk_copy_from_psa() and
      mbedtls_pk_copy_public_from_psa() provide ways to set up a PK context
      with the same content as a PSA key.
    * Add new accessors to expose the private session-id,
      session-id length, and ciphersuite-id members of
      `mbedtls_ssl_session` structure.
      Add new accessor to expose the ciphersuite-id of
      `mbedtls_ssl_ciphersuite_t` structure.Design ref: #8529
    * Mbed TLS now supports the writing and reading of TLS 1.3 early data (see
      docs/tls13-early-data.md). The support enablement is controlled at build
      time by the MBEDTLS_SSL_EARLY_DATA configuration option and at runtime by
      the mbedtls_ssl_conf_early_data() API (by default disabled in both cases).
    * Add protection for multithreaded access to the PSA keystore and protection
      for multithreaded access to the the PSA global state, including
      concurrently calling psa_crypto_init() when MBEDTLS_THREADING_C and
      MBEDTLS_THREADING_PTHREAD are defined. See
      docs/architecture/psa-thread-safety/psa-thread-safety.md for more details.
      Resolves issues #3263 and #7945.
 
 Security
    * Fix a stack buffer overread (less than 256 bytes) when parsing a TLS 1.3
      ClientHello in a TLS 1.3 server supporting some PSK key exchange mode. A
      malicious client could cause information disclosure or a denial of service.
      Fixes CVE-2024-30166.
    * Passing buffers that are stored in untrusted memory as arguments
      to PSA functions is now secure by default.
      The PSA core now protects against modification of inputs or exposure
      of intermediate outputs during operations. This is currently implemented
      by copying buffers.
      This feature increases code size and memory usage. If buffers passed to
      PSA functions are owned exclusively by the PSA core for the duration of
      the function call (i.e. no buffer parameters are in shared memory),
      copying may be disabled by setting MBEDTLS_PSA_ASSUME_EXCLUSIVE_BUFFERS.
      Note that setting this option will cause input-output buffer overlap to
      be only partially supported (#3266).
      Fixes CVE-2024-28960.
    * Restore the maximum TLS version to be negotiated to the configured one
      when an SSL context is reset with the mbedtls_ssl_session_reset() API.
      An attacker was able to prevent an Mbed TLS server from establishing any
      TLS 1.3 connection potentially resulting in a Denial of Service or forced
      version downgrade from TLS 1.3 to TLS 1.2. Fixes #8654 reported by hey3e.
      Fixes CVE-2024-28755.
    * When negotiating TLS version on server side, do not fall back to the
      TLS 1.2 implementation of the protocol if it is disabled.
      - If the TLS 1.2 implementation was disabled at build time, a TLS 1.2
        client could put the TLS 1.3-only server in an infinite loop processing
        a TLS 1.2 ClientHello, resulting in a denial of service. Reported by
        Matthias Mucha and Thomas Blattmann, SICK AG.
      - If the TLS 1.2 implementation was disabled at runtime, a TLS 1.2 client
        was able to successfully establish a TLS 1.2 connection with the server.
        Reported by alluettiv on GitHub.
     Fixes CVE-2024-28836.
 
 Bugfix
    * Fix the build with CMake when Everest or P256-m is enabled through
      a user configuration file or the compiler command line. Fixes #8165.
    * Fix compilation error in C++ programs when MBEDTLS_ASN1_PARSE_C is
      disabled.
    * Fix possible NULL dereference issue in X509 cert_req program if an entry
      in the san parameter is not separated by a colon.
    * Fix possible NULL dereference issue in X509 cert_write program if an entry
      in the san parameter is not separated by a colon.
    * Fix an inconsistency between implementations and usages of `__cpuid`,
      which mainly causes failures when building Windows target using
      mingw or clang. Fixes #8334 & #8332.
    * Fix build failure in conda-forge.  Fixes #8422.
    * Fix parsing of CSRs with critical extensions.
    * Switch to milliseconds as the unit for ticket creation and reception time
      instead of seconds. That avoids rounding errors when computing the age of
      tickets compared to peer using a millisecond clock (observed with GnuTLS).
      Fixes #6623.
    * Fix TLS server accepting TLS 1.2 handshake while TLS 1.2
      is disabled at runtime. Fixes #8593.
    * Remove accidental introduction of RSA signature algorithms
      in TLS Suite B Profile. Fixes #8221.
    * Fix unsupported PSA asymmetric encryption and decryption
      (psa_asymmetric_[en|de]crypt) with opaque keys.
      Resolves #8461.
    * On Linux on ARMv8, fix a build error with SHA-256 and SHA-512
      acceleration detection when the libc headers do not define the
      corresponding constant. Reported by valord577.
    * Correct initial capacities for key derivation algorithms:TLS12_PRF,
      TLS12_PSK_TO_MS, PBKDF2-HMAC, PBKDF2-CMAC
    * Fix mbedtls_pk_get_bitlen() for RSA keys whose size is not a
      multiple of 8. Fixes #868.
    * Avoid segmentation fault caused by releasing not initialized
      entropy resource in gen_key example. Fixes #8809.
    * mbedtls_pem_read_buffer() now performs a check on the padding data of
      decrypted keys and it rejects invalid ones.
    * Fix mbedtls_pk_sign(), mbedtls_pk_verify(), mbedtls_pk_decrypt() and
      mbedtls_pk_encrypt() on non-opaque RSA keys to honor the padding mode in
      the RSA context. Before, if MBEDTLS_USE_PSA_CRYPTO was enabled and the
      RSA context was configured for PKCS#1 v2.1 (PSS/OAEP), the sign/verify
      functions performed a PKCS#1 v1.5 signature instead and the
      encrypt/decrypt functions returned an error. Fixes #8824.
    * Fix missing bitflags in SSL session serialization headers. Their absence
      allowed SSL sessions saved in one configuration to be loaded in a
      different, incompatible configuration.
    * In TLS 1.3 clients, fix an interoperability problem due to the client
      generating a new random after a HelloRetryRequest. Fixes #8669.
    * Fix the restoration of the ALPN when loading serialized connection with
      the mbedtls_ssl_context_load() API.
    * Fix NULL pointer dereference in mbedtls_pk_verify_ext() when called using
      an opaque RSA context and specifying MBEDTLS_PK_RSASSA_PSS as key type.
    * Fix RSA opaque keys always using PKCS1 v1.5 algorithms instead of the
      primary algorithm of the wrapped PSA key.
    * Fully support arbitrary overlap between inputs and outputs of PSA
      functions. Note that overlap is still only partially supported when
      MBEDTLS_PSA_ASSUME_EXCLUSIVE_BUFFERS is set (#3266).
 
 Changes
    * Use heap memory to allocate DER encoded public/private key.
      This reduces stack usage significantly for writing a public/private
      key to a PEM string.
    * PSA_WANT_ALG_CCM and PSA_WANT_ALG_CCM_STAR_NO_TAG are no more synonyms and
      they are now treated separately. This means that they should be
      individually enabled in order to enable respective support; also the
      corresponding MBEDTLS_PSA_ACCEL symbol should be defined in case
      acceleration is required.
    * Moved declaration of functions mbedtls_ecc_group_to_psa and
      mbedtls_ecc_group_of_psa from psa/crypto_extra.h to mbedtls/psa_util.h
    * mbedtls_pk_sign_ext() is now always available, not just when
      PSA (MBEDTLS_PSA_CRYPTO_C) is enabled.
    * Extended PSA Crypto configurations options for FFDH by making it possible
      to select only some of the parameters / groups, with the macros
      PSA_WANT_DH_RFC7919_XXXX. You now need to defined the corresponding macro
      for each size you want to support. Also, if you have an FFDH accelerator,
      you'll need to define the appropriate MBEDTLS_PSA_ACCEL macros to signal
      support for these domain parameters.
    * RSA support in PSA no longer auto-enables the pkparse and pkwrite modules,
      saving code size when those are not otherwise enabled.
    * mbedtls_mpi_exp_mod and code that uses it, notably RSA and DHM operations,
      have changed their speed/memory compromise as part of a proactive security
      improvement. The new default value of MBEDTLS_MPI_WINDOW_SIZE roughly
      preserves the current speed, at the expense of increasing memory
      consumption.
    * Rename directory containing Visual Studio files from visualc/VS2013 to
      visualc/VS2017.
    * The TLS 1.3 protocol is now enabled in the default configuration.
 
 = Mbed TLS 3.5.2 branch released 2024-01-26
 
 Security
    * Fix a timing side channel in private key RSA operations. This side channel
      could be sufficient for an attacker to recover the plaintext. A local
      attacker or a remote attacker who is close to the victim on the network
      might have precise enough timing measurements to exploit this. It requires
      the attacker to send a large number of messages for decryption. For
      details, see "Everlasting ROBOT: the Marvin Attack", Hubert Kario. Reported
      by Hubert Kario, Red Hat.
    * Fix a failure to validate input when writing x509 extensions lengths which
      could result in an integer overflow, causing a zero-length buffer to be
      allocated to hold the extension. The extension would then be copied into
      the buffer, causing a heap buffer overflow.
 
 = Mbed TLS 3.5.1 branch released 2023-11-06
 
 Changes
    *  Mbed TLS is now released under a dual Apache-2.0 OR GPL-2.0-or-later
       license. Users may choose which license they take the code under.
 
 Bugfix
    * Fix accidental omission of MBEDTLS_TARGET_PREFIX in 3rdparty modules
      in CMake.
 
 = Mbed TLS 3.5.0 branch released 2023-10-05
 
 API changes
    * Mbed TLS 3.4 introduced support for omitting the built-in implementation
      of ECDSA and/or EC J-PAKE when those are provided by a driver. However,
      there was a flaw in the logic checking if the built-in implementation, in
      that it failed to check if all the relevant curves were supported by the
      accelerator. As a result, it was possible to declare no curves as
      accelerated and still have the built-in implementation compiled out.
      Starting with this release, it is necessary to declare which curves are
      accelerated (using MBEDTLS_PSA_ACCEL_ECC_xxx macros), or they will be
      considered not accelerated, and the built-in implementation of the curves
      and any algorithm possible using them will be included in the build.
    * Add new millisecond time type `mbedtls_ms_time_t` and `mbedtls_ms_time()`
      function, needed for TLS 1.3 ticket lifetimes. Alternative implementations
      can be created using an ALT interface.
 
 Requirement changes
    * Officially require Python 3.8 now that earlier versions are out of support.
    * Minimum required Windows version is now Windows Vista, or
      Windows Server 2008.
 
 New deprecations
    * PSA_WANT_KEY_TYPE_xxx_KEY_PAIR and
      MBEDTLS_PSA_ACCEL_KEY_TYPE_xxx_KEY_PAIR, where xxx is either ECC or RSA,
      are now being deprecated in favor of PSA_WANT_KEY_TYPE_xxx_KEY_PAIR_yyy and
      MBEDTLS_PSA_ACCEL_KEY_TYPE_xxx_KEY_PAIR_yyy. Here yyy can be: BASIC,
      IMPORT, EXPORT, GENERATE, DERIVE. The goal is to have a finer detail about
      the capabilities of the PSA side for either key.
    * MBEDTLS_CIPHER_BLKSIZE_MAX is deprecated in favor of
      MBEDTLS_MAX_BLOCK_LENGTH (if you intended what the name suggests:
      maximum size of any supported block cipher) or the new name
      MBEDTLS_CMAC_MAX_BLOCK_SIZE (if you intended the actual semantics:
      maximum size of a block cipher supported by the CMAC module).
    * mbedtls_pkcs5_pbes2() and mbedtls_pkcs12_pbe() functions are now
      deprecated in favor of mbedtls_pkcs5_pbes2_ext() and
      mbedtls_pkcs12_pbe_ext() as they offer more security by checking
      for overflow of the output buffer and reporting the actual length
      of the output.
 
 Features
    * All modules that use hashes or HMAC can now take advantage of PSA Crypto
      drivers when MBEDTLS_PSA_CRYPTO_C is enabled and psa_crypto_init() has
      been called. Previously (in 3.3), this was restricted to a few modules,
      and only in builds where MBEDTLS_MD_C was disabled; in particular the
      entropy module was not covered which meant an external RNG had to be
      provided - these limitations are lifted in this version. A new set of
      feature macros, MBEDTLS_MD_CAN_xxx, has been introduced that can be used
      to check for availability of hash algorithms, regardless of whether
      they're provided by a built-in implementation, a driver or both. See
      docs/driver-only-builds.md.
    * When a PSA driver for ECDH is present, it is now possible to disable
      MBEDTLS_ECDH_C in the build in order to save code size. For TLS 1.2
      key exchanges based on ECDH(E) to work, this requires
      MBEDTLS_USE_PSA_CRYPTO. Restartable/interruptible ECDHE operations in
      TLS 1.2 (ECDHE-ECDSA key exchange) are not supported in those builds yet,
      as PSA does not have an API for restartable ECDH yet.
    * When all of ECDH, ECDSA and EC J-PAKE are either disabled or provided by
      a driver, it is possible to disable MBEDTLS_ECP_C (and MBEDTLS_BIGNUM_C
      if not required by another module) and still get support for ECC keys and
      algorithms in PSA, with some limitations. See docs/driver-only-builds.txt
      for details.
    * Add parsing of directoryName subtype for subjectAltName extension in
      x509 certificates.
    * Add support for server-side TLS version negotiation. If both TLS 1.2 and
      TLS 1.3 protocols are enabled, the TLS server now selects TLS 1.2 or
      TLS 1.3 depending on the capabilities and preferences of TLS clients.
      Fixes #6867.
    * X.509 hostname verification now supports IPAddress Subject Alternate Names.
    * Add support for reading and writing X25519 and X448
      public and private keys in RFC 8410 format using the existing PK APIs.
    * When parsing X.509 certificates, support the extensions
      SignatureKeyIdentifier and AuthorityKeyIdentifier.
    * Don't include the PSA dispatch functions for PAKEs (psa_pake_setup() etc)
      if no PAKE algorithms are requested
    * Add support for the FFDH algorithm and DH key types in PSA, with
      parameters from RFC 7919. This includes a built-in implementation based
      on MBEDTLS_BIGNUM_C, and a driver dispatch layer enabling alternative
      implementations of FFDH through the driver entry points.
    * It is now possible to generate certificates with SubjectAltNames.
      Currently supported subtypes: DnsName, UniformResourceIdentifier,
      IP address, OtherName, and DirectoryName, as defined in RFC 5280.
      See mbedtls_x509write_crt_set_subject_alternative_name for
      more information.
    * X.509 hostname verification now partially supports URI Subject Alternate
      Names. Only exact matching, without any normalization procedures
      described in 7.4 of RFC5280, will result in a positive URI verification.
    * Add function mbedtls_oid_from_numeric_string() to parse an OID from a
      string to a DER-encoded mbedtls_asn1_buf.
    * Add SHA-3 family hash functions.
    * Add support to restrict AES to 128-bit keys in order to save code size.
      A new configuration option, MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH, can be
      used to enable this feature.
    * AES performance improvements. Uplift varies by platform,
      toolchain, optimisation flags and mode.
      Aarch64, gcc -Os and CCM, GCM and XTS benefit the most.
      On Aarch64, uplift is typically around 20 - 110%.
      When compiling with gcc -Os on Aarch64, AES-XTS improves
      by 4.5x.
    * Add support for PBKDF2-HMAC through the PSA API.
    * New symbols PSA_WANT_KEY_TYPE_xxx_KEY_PAIR_yyy and
      MBEDTLS_PSA_ACCEL_KEY_TYPE_xxx_KEY_PAIR_yyy (where xxx is either ECC, RSA
      or DH) were introduced in order to have finer accuracy in defining the
      PSA capabilities for each key. These capabilities, named yyy above, can be
      any of: BASIC, IMPORT, EXPORT, GENERATE, DERIVE.
      - DERIVE is only available for ECC keys, not for RSA or DH ones.
      - implementations are free to enable more than what it was strictly
        requested. For example BASIC internally enables IMPORT and EXPORT
        (useful for testing purposes), but this might change in the future.
    * Add support for FFDH key exchange in TLS 1.3.
      This is automatically enabled as soon as PSA_WANT_ALG_FFDH
      and the ephemeral or psk-ephemeral key exchange mode are enabled.
      By default, all groups are offered; the list of groups can be
      configured using the existing API function mbedtls_ssl_conf_groups().
    * Improve mbedtls_x509_time performance and reduce memory use.
    * Reduce syscalls to time() during certificate verification.
    * Allow MBEDTLS_CONFIG_FILE and MBEDTLS_USER_CONFIG_FILE to be set by
      setting the CMake variable of the same name at configuration time.
    * Add getter (mbedtls_ssl_cache_get_timeout()) to access
      `mbedtls_ssl_cache_context.timeout`.
    * Add getter (mbedtls_ssl_get_hostname()) to access
      `mbedtls_ssl_context.hostname`.
    * Add getter (mbedtls_ssl_conf_get_endpoint()) to access
      `mbedtls_ssl_config.endpoint`.
    * Support for "opaque" (PSA-held) ECC keys in the PK module has been
      extended: it is now possible to use mbedtls_pk_write_key_der(),
      mbedtls_pk_write_key_pem(), mbedtls_pk_check_pair(), and
      mbedtls_pk_verify() with opaque ECC keys (provided the PSA attributes
      allow it).
    * The documentation of mbedtls_ecp_group now describes the optimized
      representation of A for some curves. Fixes #8045.
    * Add a possibility to generate CSR's with RCF822 and directoryName subtype
      of subjectAltName extension in x509 certificates.
    * Add support for PBKDF2-CMAC through the PSA API.
    * New configuration option MBEDTLS_AES_USE_HARDWARE_ONLY introduced. When
      using CPU-accelerated AES (e.g., Arm Crypto Extensions), this option
      disables the plain C implementation and the run-time detection for the
      CPU feature, which reduces code size and avoids the vulnerability of the
      plain C implementation.
    * Accept arbitrary AttributeType and AttributeValue in certificate
      Distinguished Names using RFC 4514 syntax.
    * Applications using ECC over secp256r1 through the PSA API can use a
      new implementation with a much smaller footprint, but some minor
      usage restrictions. See the documentation of the new configuration
      option MBEDTLS_PSA_P256M_DRIVER_ENABLED for details.
 
 Security
    * Fix a case where potentially sensitive information held in memory would not
      be completely zeroized during TLS 1.2 handshake, in both server and client
      configurations.
    * In configurations with ARIA or Camellia but not AES, the value of
      MBEDTLS_CIPHER_BLKSIZE_MAX was 8, rather than 16 as the name might
      suggest. This did not affect any library code, because this macro was
      only used in relation with CMAC which does not support these ciphers.
      This may affect application code that uses this macro.
    * Developers using mbedtls_pkcs5_pbes2() or mbedtls_pkcs12_pbe() should
      review the size of the output buffer passed to this function, and note
      that the output after decryption may include CBC padding. Consider moving
      to the new functions mbedtls_pkcs5_pbes2_ext() or mbedtls_pkcs12_pbe_ext()
      which checks for overflow of the output buffer and reports the actual
      length of the output.
    * Improve padding calculations in CBC decryption, NIST key unwrapping and
      RSA OAEP decryption. With the previous implementation, some compilers
      (notably recent versions of Clang and IAR) could produce non-constant
      time code, which could allow a padding oracle attack if the attacker
      has access to precise timing measurements.
    * Updates to constant-time C code so that compilers are less likely to use
      conditional instructions, which can have an observable difference in
      timing. (Clang has been seen to do this.) Also introduce assembly
      implementations for 32- and 64-bit Arm and for x86 and x86-64, which are
      guaranteed not to use conditional instructions.
    * Fix definition of MBEDTLS_MD_MAX_BLOCK_SIZE, which was too
      small when MBEDTLS_SHA384_C was defined and MBEDTLS_SHA512_C was
      undefined. Mbed TLS itself was unaffected by this, but user code
      which used MBEDTLS_MD_MAX_BLOCK_SIZE could be affected. The only
      release containing this bug was Mbed TLS 3.4.0.
    * Fix a buffer overread when parsing short TLS application data records in
      null-cipher cipher suites. Credit to OSS-Fuzz.
    * Fix a remotely exploitable heap buffer overflow in TLS handshake parsing.
      In TLS 1.3, all configurations are affected except PSK-only ones, and
      both clients and servers are affected.
      In TLS 1.2, the affected configurations are those with
      MBEDTLS_USE_PSA_CRYPTO and ECDH enabled but DHM and RSA disabled,
      and only servers are affected, not clients.
      Credit to OSS-Fuzz.
 
 Bugfix
    * Fix proper sizing for PSA_EXPORT_[KEY_PAIR/PUBLIC_KEY]_MAX_SIZE and
      PSA_SIGNATURE_MAX_SIZE buffers when at least one accelerated EC is bigger
      than all built-in ones and RSA is disabled.
      Resolves #6622.
    * Add missing md.h includes to some of the external programs from
      the programs directory. Without this, even though the configuration
      was sufficient for a particular program to work, it would only print
      a message that one of the required defines is missing.
    * Fix declaration of mbedtls_ecdsa_sign_det_restartable() function
      in the ecdsa.h header file. There was a build warning when the
      configuration macro MBEDTLS_ECDSA_SIGN_ALT was defined.
      Resolves #7407.
    * Fix an error when MBEDTLS_ECDSA_SIGN_ALT is defined but not
      MBEDTLS_ECDSA_VERIFY_ALT, causing ecdsa verify to fail. Fixes #7498.
    * Fix missing PSA initialization in sample programs when
      MBEDTLS_USE_PSA_CRYPTO is enabled.
    * Fix the J-PAKE driver interface for user and peer to accept any values
      (previously accepted values were limited to "client" or "server").
    * Fix clang and armclang compilation error when targeting certain Arm
      M-class CPUs (Cortex-M0, Cortex-M0+, Cortex-M1, Cortex-M23,
      SecurCore SC000). Fixes #1077.
    * Fix "unterminated '#pragma clang attribute push'" in sha256/sha512.c when
      built with MBEDTLS_SHAxxx_USE_A64_CRYPTO_IF_PRESENT but don't have a
      way to detect the crypto extensions required. A warning is still issued.
    * Fixed an issue that caused compile errors when using CMake and the IAR
      toolchain.
    * Fix very high stack usage in SSL debug code. Reported by Maximilian
      Gerhardt in #7804.
    * Fix a compilation failure in the constant_time module when
      building for arm64_32 (e.g., for watchos). Reported by Paulo
      Coutinho in #7787.
    * Fix crypt_and_hash decryption fail when used with a stream cipher
      mode of operation due to the input not being multiple of block size.
      Resolves #7417.
    * Fix a bug in which mbedtls_x509_string_to_names() would return success
      when given a invalid name string if it did not contain '=' or ','.
    * Fix compilation warnings in aes.c, which prevented the
      example TF-M configuration in configs/ from building cleanly:
      tfm_mbedcrypto_config_profile_medium.h with
      crypto_config_profile_medium.h.
    * In TLS 1.3, fix handshake failure when a client in its ClientHello
      proposes an handshake based on PSK only key exchange mode or at least
      one of the key exchange modes using ephemeral keys to a server that
      supports only the PSK key exchange mode.
    * Fix CCM* with no tag being not supported in a build with CCM as the only
      symmetric encryption algorithm and the PSA configuration enabled.
    * Fix the build with MBEDTLS_PSA_INJECT_ENTROPY. Fixes #7516.
    * Fix a compilation error on some platforms when including mbedtls/ssl.h
      with all TLS support disabled. Fixes #6628.
    * Fix x509 certificate generation to conform to RFC 5480 / RFC 5758 when
      using ECC key. The certificate was rejected by some crypto frameworks.
      Fixes #2924.
    * Fix a potential corruption of the passed-in IV when mbedtls_aes_crypt_cbc()
      is called with zero length and padlock is not enabled.
    * Fix compile failure due to empty enum in cipher_wrap.c, when building
      with a very minimal configuration. Fixes #7625.
    * Fix some cases where mbedtls_mpi_mod_exp, RSA key construction or ECDSA
      signature can silently return an incorrect result in low memory conditions.
    * Don't try to include MBEDTLS_PSA_CRYPTO_USER_CONFIG_FILE when
      MBEDTLS_PSA_CRYPTO_CONFIG is disabled.
    * Fix IAR compiler warnings.
    * Fix an issue when parsing an otherName subject alternative name into a
      mbedtls_x509_san_other_name struct. The type-id of the otherName was not
      copied to the struct. This meant that the struct had incomplete
      information about the otherName SAN and contained uninitialized memory.
    * Fix the detection of HardwareModuleName otherName SANs. These were being
      detected by comparing the wrong field and the check was erroneously
      inverted.
    * Fix a build error in some configurations with MBEDTLS_PSA_CRYPTO_CONFIG
      enabled, where some low-level modules required by requested PSA crypto
      features were not getting automatically enabled. Fixes #7420.
    * Fix undefined symbols in some builds using TLS 1.3 with a custom
      configuration file.
    * Fix log level for the got supported group message. Fixes #6765
    * Functions in the ssl_cache module now return a negative MBEDTLS_ERR_xxx
      error code on failure. Before, they returned 1 to indicate failure in
      some cases involving a missing entry or a full cache.
    * mbedtls_pk_parse_key() now rejects trailing garbage in encrypted keys.
    * Fix the build with CMake when Everest or P256-m is enabled through
      a user configuration file or the compiler command line. Fixes #8165.
 
 Changes
    * Enable Arm / Thumb bignum assembly for most Arm platforms when
      compiling with gcc, clang or armclang and -O0.
    * Enforce minimum RSA key size when generating a key
      to avoid accidental misuse.
    * Use heap memory to allocate DER encoded RSA private key.
      This reduces stack usage significantly for RSA signature
      operations when MBEDTLS_PSA_CRYPTO_C is defined.
    * Update Windows code to use BCryptGenRandom and wcslen, and
      ensure that conversions between size_t, ULONG, and int are
      always done safely.  Original contribution by Kevin Kane #635, #730
      followed by Simon Butcher #1453.
    * Users integrating their own PSA drivers should be aware that
      the file library/psa_crypto_driver_wrappers.c has been renamed
      to psa_crypto_driver_wrappers_no_static.c.
    * When using CBC with the cipher module, the requirement to call
      mbedtls_cipher_set_padding_mode() is now enforced. Previously, omitting
      this call accidentally applied a default padding mode chosen at compile
      time.
 
 = Mbed TLS 3.4.1 branch released 2023-08-04
 
 Bugfix
    * Fix builds on Windows with clang
 
 Changes
    * Update test data to avoid failures of unit tests after 2023-08-07.
 
 = Mbed TLS 3.4.0 branch released 2023-03-28
 
 Default behavior changes
    * The default priority order of TLS 1.3 cipher suites has been modified to
      follow the same rules as the TLS 1.2 cipher suites (see
      ssl_ciphersuites.c). The preferred cipher suite is now
      TLS_CHACHA20_POLY1305_SHA256.
 
 New deprecations
    * mbedtls_x509write_crt_set_serial() is now being deprecated in favor of
      mbedtls_x509write_crt_set_serial_raw(). The goal here is to remove any
      direct dependency of X509 on BIGNUM_C.
    * PSA to mbedtls error translation is now unified in psa_util.h,
      deprecating mbedtls_md_error_from_psa. Each file that performs error
      translation should define its own version of PSA_TO_MBEDTLS_ERR,
      optionally providing file-specific error pairs. Please see psa_util.h for
      more details.
 
 Features
    * Added partial support for parsing the PKCS #7 Cryptographic Message
      Syntax, as defined in RFC 2315. Currently, support is limited to the
      following:
      - Only the signed-data content type, version 1 is supported.
      - Only DER encoding is supported.
      - Only a single digest algorithm per message is supported.
      - Certificates must be in X.509 format. A message must have either 0
        or 1 certificates.
      - There is no support for certificate revocation lists.
      - The authenticated and unauthenticated attribute fields of SignerInfo
        must be empty.
      Many thanks to Daniel Axtens, Nayna Jain, and Nick Child from IBM for
      contributing this feature, and to Demi-Marie Obenour for contributing
      various improvements, tests and bug fixes.
    * General performance improvements by accessing multiple bytes at a time.
      Fixes #1666.
    * Improvements to use of unaligned and byte-swapped memory, reducing code
      size and improving performance (depending on compiler and target
      architecture).
    * Add support for reading points in compressed format
      (MBEDTLS_ECP_PF_COMPRESSED) with mbedtls_ecp_point_read_binary()
      (and callers) for Short Weierstrass curves with prime p where p = 3 mod 4
      (all mbedtls MBEDTLS_ECP_DP_SECP* and MBEDTLS_ECP_DP_BP* curves
       except MBEDTLS_ECP_DP_SECP224R1 and MBEDTLS_ECP_DP_SECP224K1)
    * SHA224_C/SHA384_C are now independent from SHA384_C/SHA512_C respectively.
      This helps in saving code size when some of the above hashes are not
      required.
    * Add parsing of V3 extensions (key usage, Netscape cert-type,
      Subject Alternative Names) in x509 Certificate Sign Requests.
    * Use HOSTCC (if it is set) when compiling C code during generation of the
      configuration-independent files. This allows them to be generated when
      CC is set for cross compilation.
    * Add parsing of uniformResourceIdentifier subtype for subjectAltName
      extension in x509 certificates.
    * Add an interruptible version of sign and verify hash to the PSA interface,
      backed by internal library support for ECDSA signing and verification.
    * Add parsing of rfc822Name subtype for subjectAltName
      extension in x509 certificates.
    * The configuration macros MBEDTLS_PSA_CRYPTO_PLATFORM_FILE and
      MBEDTLS_PSA_CRYPTO_STRUCT_FILE specify alternative locations for
      the headers "psa/crypto_platform.h" and "psa/crypto_struct.h".
    * When a PSA driver for ECDSA is present, it is now possible to disable
      MBEDTLS_ECDSA_C in the build in order to save code size. For PK, X.509
      and TLS to fully work, this requires MBEDTLS_USE_PSA_CRYPTO to be enabled.
      Restartable/interruptible ECDSA operations in PK, X.509 and TLS are not
      supported in those builds yet, as driver support for interruptible ECDSA
      operations is not present yet.
    * Add a driver dispatch layer for EC J-PAKE, enabling alternative
      implementations of EC J-PAKE through the driver entry points.
    * Add new API mbedtls_ssl_cache_remove for cache entry removal by
      its session id.
    * Add support to include the SubjectAltName extension to a CSR.
    * Add support for AES with the Armv8-A Cryptographic Extension on
      64-bit Arm. A new configuration option, MBEDTLS_AESCE_C, can
      be used to enable this feature. Run-time detection is supported
      under Linux only.
    * When a PSA driver for EC J-PAKE is present, it is now possible to disable
      MBEDTLS_ECJPAKE_C in the build in order to save code size. For the
      corresponding TLS 1.2 key exchange to work, MBEDTLS_USE_PSA_CRYPTO needs
      to be enabled.
    * Add functions mbedtls_rsa_get_padding_mode() and mbedtls_rsa_get_md_alg()
      to read non-public fields for padding mode and hash id from
      an mbedtls_rsa_context, as requested in #6917.
    * AES-NI is now supported with Visual Studio.
    * AES-NI is now supported in 32-bit builds, or when MBEDTLS_HAVE_ASM
      is disabled, when compiling with GCC or Clang or a compatible compiler
      for a target CPU that supports the requisite instructions (for example
      gcc -m32 -msse2 -maes -mpclmul). (Generic x86 builds with GCC-like
      compilers still require MBEDTLS_HAVE_ASM and a 64-bit target.)
    * It is now possible to use a PSA-held (opaque) password with the TLS 1.2
      ECJPAKE key exchange, using the new API function
      mbedtls_ssl_set_hs_ecjpake_password_opaque().
 
 Security
    * Use platform-provided secure zeroization function where possible, such as
      explicit_bzero().
    * Zeroize SSL cache entries when they are freed.
    * Fix a potential heap buffer overread in TLS 1.3 client-side when
      MBEDTLS_DEBUG_C is enabled. This may result in an application crash.
    * Add support for AES with the Armv8-A Cryptographic Extension on 64-bit
      Arm, so that these systems are no longer vulnerable to timing side-channel
      attacks. This is configured by MBEDTLS_AESCE_C, which is on by default.
      Reported by Demi Marie Obenour.
    * MBEDTLS_AESNI_C, which is enabled by default, was silently ignored on
      builds that couldn't compile the GCC-style assembly implementation
      (most notably builds with Visual Studio), leaving them vulnerable to
      timing side-channel attacks. There is now an intrinsics-based AES-NI
      implementation as a fallback for when the assembly one cannot be used.
 
 Bugfix
    * Fix possible integer overflow in mbedtls_timing_hardclock(), which
      could cause a crash in programs/test/benchmark.
    * Fix IAR compiler warnings. Fixes #6924.
    * Fix a bug in the build where directory names containing spaces were
      causing generate_errors.pl to error out resulting in a build failure.
      Fixes issue #6879.
    * In TLS 1.3, when using a ticket for session resumption, tweak its age
      calculation on the client side. It prevents a server with more accurate
      ticket timestamps (typically timestamps in milliseconds) compared to the
      Mbed TLS ticket timestamps (in seconds) to compute a ticket age smaller
      than the age computed and transmitted by the client and thus potentially
      reject the ticket. Fix #6623.
    * Fix compile error where MBEDTLS_RSA_C and MBEDTLS_X509_CRT_WRITE_C are
      defined, but MBEDTLS_PK_RSA_ALT_SUPPORT is not defined. Fixes #3174.
    * List PSA_WANT_ALG_CCM_STAR_NO_TAG in psa/crypto_config.h so that it can
      be toggled with config.py.
    * The key derivation algorithm PSA_ALG_TLS12_ECJPAKE_TO_PMS cannot be
      used on a shared secret from a key agreement since its input must be
      an ECC public key. Reject this properly.
    * mbedtls_x509write_crt_set_serial() now explicitly rejects serial numbers
      whose binary representation is longer than 20 bytes. This was already
      forbidden by the standard (RFC5280 - section 4.1.2.2) and now it's being
      enforced also at code level.
    * Fix potential undefined behavior in mbedtls_mpi_sub_abs().  Reported by
      Pascal Cuoq using TrustInSoft Analyzer in #6701; observed independently by
      Aaron Ucko under Valgrind.
    * Fix behavior of certain sample programs which could, when run with no
      arguments, access uninitialized memory in some cases. Fixes #6700 (which
      was found by TrustInSoft Analyzer during REDOCS'22) and #1120.
    * Fix parsing of X.509 SubjectAlternativeName extension. Previously,
      malformed alternative name components were not caught during initial
      certificate parsing, but only on subsequent calls to
      mbedtls_x509_parse_subject_alt_name(). Fixes #2838.
    * Make the fields of mbedtls_pk_rsassa_pss_options public. This makes it
      possible to verify RSA PSS signatures with the pk module, which was
      inadvertently broken since Mbed TLS 3.0.
    * Fix bug in conversion from OID to string in
      mbedtls_oid_get_numeric_string(). OIDs such as 2.40.0.25 are now printed
      correctly.
    * Reject OIDs with overlong-encoded subidentifiers when converting
      them to a string.
    * Reject OIDs with subidentifier values exceeding UINT_MAX.  Such
      subidentifiers can be valid, but Mbed TLS cannot currently handle them.
    * Reject OIDs that have unterminated subidentifiers, or (equivalently)
      have the most-significant bit set in their last byte.
    * Silence warnings from clang -Wdocumentation about empty \retval
      descriptions, which started appearing with Clang 15. Fixes #6960.
    * Fix the handling of renegotiation attempts in TLS 1.3. They are now
      systematically rejected.
    * Fix an unused-variable warning in TLS 1.3-only builds if
      MBEDTLS_SSL_RENEGOTIATION was enabled. Fixes #6200.
    * Fix undefined behavior in mbedtls_ssl_read() and mbedtls_ssl_write() if
      len argument is 0 and buffer is NULL.
    * Allow setting user and peer identifiers for EC J-PAKE operation
      instead of role in PAKE PSA Crypto API as described in the specification.
      This is a partial fix that allows only "client" and "server" identifiers.
    * Fix a compilation error when PSA Crypto is built with support for
      TLS12_PRF but not TLS12_PSK_TO_MS. Reported by joerchan in #7125.
    * In the TLS 1.3 server, select the preferred client cipher suite, not the
      least preferred. The selection error was introduced in Mbed TLS 3.3.0.
    * Fix TLS 1.3 session resumption when the established pre-shared key is
      384 bits long. That is the length of pre-shared keys created under a
      session where the cipher suite is TLS_AES_256_GCM_SHA384.
    * Fix an issue when compiling with MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT
      enabled, which required specifying compiler flags enabling SHA3 Crypto
      Extensions, where some compilers would emit EOR3 instructions in other
      modules, which would then fail if run on a CPU without the SHA3
      extensions. Fixes #5758.
 
 Changes
    * Install the .cmake files into CMAKE_INSTALL_LIBDIR/cmake/MbedTLS,
      typically /usr/lib/cmake/MbedTLS.
    * Mixed-endian systems are explicitly not supported any more.
    * When MBEDTLS_USE_PSA_CRYPTO and MBEDTLS_ECDSA_DETERMINISTIC are both
      defined, mbedtls_pk_sign() now use deterministic ECDSA for ECDSA
      signatures. This aligns the behaviour with MBEDTLS_USE_PSA_CRYPTO to
      the behaviour without it, where deterministic ECDSA was already used.
    * Visual Studio: Rename the directory containing Visual Studio files from
      visualc/VS2010 to visualc/VS2013 as we do not support building with versions
      older than 2013. Update the solution file to specify VS2013 as a minimum.
    * programs/x509/cert_write:
      - now it accepts the serial number in 2 different formats: decimal and
        hex. They cannot be used simultaneously
      - "serial" is used for the decimal format and it's limted in size to
        unsigned long long int
      - "serial_hex" is used for the hex format; max length here is
        MBEDTLS_X509_RFC5280_MAX_SERIAL_LEN*2
    * The C code follows a new coding style. This is transparent for users but
      affects contributors and maintainers of local patches. For more
      information, see
      https://mbed-tls.readthedocs.io/en/latest/kb/how-to/rewrite-branch-for-coding-style/
    * Changed the default MBEDTLS_ECP_WINDOW_SIZE from 6 to 2.
      As tested in issue 6790, the correlation between this define and
      RSA decryption performance has changed lately due to security fixes.
      To fix the performance degradation when using default values the
      window was reduced from 6 to 2, a value that gives the best or close
      to best results when tested on Cortex-M4 and Intel i7.
    * When enabling MBEDTLS_SHA256_USE_A64_CRYPTO_* or
      MBEDTLS_SHA512_USE_A64_CRYPTO_*, it is no longer necessary to specify
      compiler target flags on the command line; the library now sets target
      options within the appropriate modules.
 
 = Mbed TLS 3.3.0 branch released 2022-12-14
 
 Default behavior changes
    * Previously the macro MBEDTLS_SSL_DTLS_CONNECTION_ID implemented version 05
      of the IETF draft, and was marked experimental and disabled by default.
      It is now no longer experimental, and implements the final version from
      RFC 9146, which is not interoperable with the draft-05 version.
      If you need to communicate with peers that use earlier versions of
      Mbed TLS, then you need to define MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT
      to 1, but then you won't be able to communicate with peers that use the
      standard (non-draft) version.
      If you need to interoperate with both classes of peers with the
      same build of Mbed TLS, please let us know about your situation on the
      mailing list or GitHub.
 
 Requirement changes
    * When building with PSA drivers using generate_driver_wrappers.py, or
      when building the library from the development branch rather than
      from a release, the Python module jsonschema is now necessary, in
      addition to jinja2. The official list of required Python modules is
      maintained in scripts/basic.requirements.txt and may change again
      in the future.
 
 New deprecations
    * Deprecate mbedtls_asn1_free_named_data().
      Use mbedtls_asn1_free_named_data_list()
      or mbedtls_asn1_free_named_data_list_shallow().
 
 Features
    * Support rsa_pss_rsae_* signature algorithms in TLS 1.2.
    * make: enable building unversioned shared library, with e.g.:
      "SHARED=1 SOEXT_TLS=so SOEXT_X509=so SOEXT_CRYPTO=so make lib"
      resulting in library names like "libmbedtls.so" rather than
      "libmbedcrypto.so.11".
    * Expose the EC J-PAKE functionality through the Draft PSA PAKE Crypto API.
      Only the ECC primitive with secp256r1 curve and SHA-256 hash algorithm
      are supported in this implementation.
    * Some modules can now use PSA drivers for hashes, including with no
      built-in implementation present, but only in some configurations.
      - RSA OAEP and PSS (PKCS#1 v2.1), PKCS5, PKCS12 and EC J-PAKE now use
        hashes from PSA when (and only when) MBEDTLS_MD_C is disabled.
      - PEM parsing of encrypted files now uses MD-5 from PSA when (and only
        when) MBEDTLS_MD5_C is disabled.
      See the documentation of the corresponding macros in mbedtls_config.h for
      details.
      Note that some modules are not able to use hashes from PSA yet, including
      the entropy module. As a consequence, for now the only way to build with
      all hashes only provided by drivers (no built-in hash) is to use
      MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG.
    * When MBEDTLS_USE_PSA_CRYPTO is enabled, X.509, TLS 1.2 and TLS 1.3 now
      properly negotiate/accept hashes based on their availability in PSA.
      As a consequence, they now work in configurations where the built-in
      implementations of (some) hashes are excluded and those hashes are only
      provided by PSA drivers. (See previous entry for limitation on RSA-PSS
      though: that module only use hashes from PSA when MBEDTLS_MD_C is off).
    * Add support for opaque keys as the private keys associated to certificates
      for authentication in TLS 1.3.
    * Add the LMS post-quantum-safe stateful-hash asymmetric signature scheme.
      Signature verification is production-ready, but generation is for testing
      purposes only. This currently only supports one parameter set
      (LMS_SHA256_M32_H10), meaning that each private key can be used to sign
      1024 messages. As such, it is not intended for use in TLS, but instead
      for verification of assets transmitted over an insecure channel,
      particularly firmware images.
    * Add the LM-OTS post-quantum-safe one-time signature scheme, which is
      required for LMS. This can be used independently, but each key can only
      be used to sign one message so is impractical for most circumstances.
    * Mbed TLS now supports TLS 1.3 key establishment via pre-shared keys.
      The pre-shared keys can be provisioned externally or via the ticket
      mechanism (session resumption).
      The ticket mechanism is supported when the configuration option
      MBEDTLS_SSL_SESSION_TICKETS is enabled.
      New options MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_xxx_ENABLED
      control the support for the three possible TLS 1.3 key exchange modes.
    * cert_write: support for setting extended key usage attributes. A
      corresponding new public API call has been added in the library,
      mbedtls_x509write_crt_set_ext_key_usage().
    * cert_write: support for writing certificate files in either PEM
      or DER format.
    * The PSA driver wrapper generator generate_driver_wrappers.py now
      supports a subset of the driver description language, including
      the following entry points: import_key, export_key, export_public_key,
      get_builtin_key, copy_key.
    * The new functions mbedtls_asn1_free_named_data_list() and
      mbedtls_asn1_free_named_data_list_shallow() simplify the management
      of memory in named data lists in X.509 structures.
    * The TLS 1.2 EC J-PAKE key exchange can now use the PSA Crypto API.
      Additional PSA key slots will be allocated in the process of such key
      exchange for builds that enable MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED and
      MBEDTLS_USE_PSA_CRYPTO.
    * Add support for DTLS Connection ID as defined by RFC 9146, controlled by
      MBEDTLS_SSL_DTLS_CONNECTION_ID (enabled by default) and configured with
      mbedtls_ssl_set_cid().
    * Add a driver dispatch layer for raw key agreement, enabling alternative
      implementations of raw key agreement through the key_agreement driver
      entry point. This entry point is specified in the proposed PSA driver
      interface, but had not yet been implemented.
    * Add an ad-hoc key derivation function handling EC J-PAKE to PMS
      calculation that can be used to derive the session secret in TLS 1.2,
      as described in draft-cragie-tls-ecjpake-01. This can be achieved by
      using PSA_ALG_TLS12_ECJPAKE_TO_PMS as the key derivation algorithm.
 
 Security
    * Fix potential heap buffer overread and overwrite in DTLS if
      MBEDTLS_SSL_DTLS_CONNECTION_ID is enabled and
      MBEDTLS_SSL_CID_IN_LEN_MAX > 2 * MBEDTLS_SSL_CID_OUT_LEN_MAX.
    * Fix an issue where an adversary with access to precise enough information
      about memory accesses (typically, an untrusted operating system attacking
      a secure enclave) could recover an RSA private key after observing the
      victim performing a single private-key operation if the window size used
      for the exponentiation was 3 or smaller. Found and reported by Zili KOU,
      Wenjian HE, Sharad Sinha, and Wei ZHANG. See "Cache Side-channel Attacks
      and Defenses of the Sliding Window Algorithm in TEEs" - Design, Automation
      and Test in Europe 2023.
 
 Bugfix
    * Refactor mbedtls_aes_context to support shallow-copying. Fixes #2147.
    * Fix an issue with in-tree CMake builds in releases with GEN_FILES
      turned off: if a shipped file was missing from the working directory,
      it could be turned into a symbolic link to itself.
    * Fix a long-standing build failure when building x86 PIC code with old
      gcc (4.x). The code will be slower, but will compile. We do however
      recommend upgrading to a more recent compiler instead. Fixes #1910.
    * Fix support for little-endian Microblaze when MBEDTLS_HAVE_ASM is defined.
      Contributed by Kazuyuki Kimura to fix #2020.
    * Use double quotes to include private header file psa_crypto_cipher.h.
      Fixes 'file not found with <angled> include' error
      when building with Xcode.
    * Fix handling of broken symlinks when loading certificates using
      mbedtls_x509_crt_parse_path(). Instead of returning an error as soon as a
      broken link is encountered, skip the broken link and continue parsing
      other certificate files. Contributed by Eduardo Silva in #2602.
    * Fix an interoperability failure between an Mbed TLS client with both
      TLS 1.2 and TLS 1.3 support, and a TLS 1.2 server that supports
      rsa_pss_rsae_* signature algorithms. This failed because Mbed TLS
      advertised support for PSS in both TLS 1.2 and 1.3, but only
      actually supported PSS in TLS 1.3.
    * Fix a compilation error when using CMake with an IAR toolchain.
      Fixes #5964.
    * Fix a build error due to a missing prototype warning when
      MBEDTLS_DEPRECATED_REMOVED is enabled.
    * Fix mbedtls_ctr_drbg_free() on an initialized but unseeded context. When
      MBEDTLS_AES_ALT is enabled, it could call mbedtls_aes_free() on an
      uninitialized context.
    * Fix a build issue on Windows using CMake where the source and build
      directories could not be on different drives. Fixes #5751.
    * Fix bugs and missing dependencies when building and testing
      configurations with only one encryption type enabled in TLS 1.2.
    * Provide the missing definition of mbedtls_setbuf() in some configurations
      with MBEDTLS_PLATFORM_C disabled. Fixes #6118, #6196.
    * Fix compilation errors when trying to build with
      PSA drivers for AEAD (GCM, CCM, Chacha20-Poly1305).
    * Fix memory leak in ssl_parse_certificate_request() caused by
      mbedtls_x509_get_name() not freeing allocated objects in case of error.
      Change mbedtls_x509_get_name() to clean up allocated objects on error.
    * Fix build failure with MBEDTLS_RSA_C and MBEDTLS_PSA_CRYPTO_C but not
      MBEDTLS_USE_PSA_CRYPTO or MBEDTLS_PK_WRITE_C. Fixes #6408.
    * Fix build failure with MBEDTLS_RSA_C and MBEDTLS_PSA_CRYPTO_C but not
      MBEDTLS_PK_PARSE_C. Fixes #6409.
    * Fix ECDSA verification, where it was not always validating the
      public key. This bug meant that it was possible to verify a
      signature with an invalid public key, in some cases. Reported by
      Guido Vranken using Cryptofuzz in #4420.
    * Fix a possible null pointer dereference if a memory allocation fails
      in TLS PRF code. Reported by Michael Madsen in #6516.
    * Fix TLS 1.3 session resumption. Fixes #6488.
    * Add a configuration check to exclude optional client authentication
      in TLS 1.3 (where it is forbidden).
    * Fix a bug in which mbedtls_x509_crt_info() would produce non-printable
      bytes when parsing certificates containing a binary RFC 4108
      HardwareModuleName as a Subject Alternative Name extension. Hardware
      serial numbers are now rendered in hex format. Fixes #6262.
    * Fix bug in error reporting in dh_genprime.c where upon failure,
      the error code returned by mbedtls_mpi_write_file() is overwritten
      and therefore not printed.
    * In the bignum module, operations of the form (-A) - (+A) or (-A) - (-A)
      with A > 0 created an unintended representation of the value 0 which was
      not processed correctly by some bignum operations. Fix this. This had no
      consequence on cryptography code, but might affect applications that call
      bignum directly and use negative numbers.
    * Fix a bug whereby the list of signature algorithms sent as part of
      the TLS 1.2 server certificate request would get corrupted, meaning the
      first algorithm would not get sent and an entry consisting of two random
      bytes would be sent instead. Found by Serban Bejan and Dudek Sebastian.
    * Fix undefined behavior (typically harmless in practice) of
      mbedtls_mpi_add_mpi(), mbedtls_mpi_add_abs() and mbedtls_mpi_add_int()
      when both operands are 0 and the left operand is represented with 0 limbs.
    * Fix undefined behavior (typically harmless in practice) when some bignum
      functions receive the most negative value of mbedtls_mpi_sint. Credit
      to OSS-Fuzz. Fixes #6597.
    * Fix undefined behavior (typically harmless in practice) in PSA ECB
      encryption and decryption.
    * Move some SSL-specific code out of libmbedcrypto where it had been placed
      accidentally.
    * Fix a build error when compiling the bignum module for some Arm platforms.
      Fixes #6089, #6124, #6217.
 
 Changes
    * Add the ability to query PSA_WANT_xxx macros to query_compile_time_config.
    * Calling AEAD tag-specific functions for non-AEAD algorithms (which
      should not be done - they are documented for use only by AES-GCM and
      ChaCha20+Poly1305) now returns MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE
      instead of success (0).
 
 = Mbed TLS 3.2.1 branch released 2022-07-12
 
 Bugfix
    *  Re-add missing generated file library/psa_crypto_driver_wrappers.c
 
 = Mbed TLS 3.2.0 branch released 2022-07-11
 
 Default behavior changes
    * mbedtls_cipher_set_iv will now fail with ChaCha20 and ChaCha20+Poly1305
      for IV lengths other than 12. The library was silently overwriting this
      length with 12, but did not inform the caller about it. Fixes #4301.
 
 Requirement changes
    * The library will no longer compile out of the box on a platform without
      setbuf(). If your platform does not have setbuf(), you can configure an
      alternative function by enabling MBEDTLS_PLATFORM_SETBUF_ALT or
      MBEDTLS_PLATFORM_SETBUF_MACRO.
 
 New deprecations
    * Deprecate mbedtls_ssl_conf_max_version() and
      mbedtls_ssl_conf_min_version() in favor of
      mbedtls_ssl_conf_max_tls_version() and
      mbedtls_ssl_conf_min_tls_version().
    * Deprecate mbedtls_cipher_setup_psa(). Use psa_aead_xxx() or
      psa_cipher_xxx() directly instead.
    * Secure element drivers enabled by MBEDTLS_PSA_CRYPTO_SE_C are deprecated.
      This was intended as an experimental feature, but had not been explicitly
      documented as such. Use opaque drivers with the interface enabled by
      MBEDTLS_PSA_CRYPTO_DRIVERS instead.
    * Deprecate mbedtls_ssl_conf_sig_hashes() in favor of the more generic
      mbedtls_ssl_conf_sig_algs(). Signature algorithms for the TLS 1.2 and
      TLS 1.3 handshake should now be configured with
      mbedtls_ssl_conf_sig_algs().
 
 Features
    * Add accessor to obtain ciphersuite id from ssl context.
    * Add accessors to get members from ciphersuite info.
    * Add mbedtls_ssl_ticket_rotate() for external ticket rotation.
    * Add accessor to get the raw buffer pointer from a PEM context.
    * The structures mbedtls_ssl_config and mbedtls_ssl_context now store
      a piece of user data which is reserved for the application. The user
      data can be either a pointer or an integer.
    * Add an accessor function to get the configuration associated with
      an SSL context.
    * Add a function to access the protocol version from an SSL context in a
      form that's easy to compare. Fixes #5407.
    * Add function mbedtls_md_info_from_ctx() to recall the message digest
      information that was used to set up a message digest context.
    * Add ALPN support in TLS 1.3 clients.
    * Add server certificate selection callback near end of Client Hello.
      Register callback with mbedtls_ssl_conf_cert_cb().
    * Provide mechanism to reset handshake cert list by calling
      mbedtls_ssl_set_hs_own_cert() with NULL value for own_cert param.
    * Add accessor mbedtls_ssl_get_hs_sni() to retrieve SNI from within
      cert callback (mbedtls_ssl_conf_cert_cb()) during handshake.
    * The X.509 module now uses PSA hash acceleration if present.
    * Add support for psa crypto key derivation for elliptic curve
      keys. Fixes #3260.
    * Add function mbedtls_timing_get_final_delay() to access the private
      final delay field in an mbedtls_timing_delay_context, as requested in
      #5183.
     * Add mbedtls_pk_sign_ext() which allows generating RSA-PSS signatures when
       PSA Crypto is enabled.
    * Add function mbedtls_ecp_export() to export ECP key pair parameters.
      Fixes #4838.
    * Add function mbedtls_ssl_is_handshake_over() to enable querying if the SSL
      Handshake has completed or not, and thus whether to continue calling
      mbedtls_ssl_handshake_step(), requested in #4383.
    * Add the function mbedtls_ssl_get_own_cid() to access our own connection id
      within mbedtls_ssl_context, as requested in #5184.
    * Introduce mbedtls_ssl_hs_cb_t typedef for use with
      mbedtls_ssl_conf_cert_cb() and perhaps future callbacks
      during TLS handshake.
    * Add functions mbedtls_ssl_conf_max_tls_version() and
      mbedtls_ssl_conf_min_tls_version() that use a single value to specify
      the protocol version.
     * Extend the existing PSA_ALG_TLS12_PSK_TO_MS() algorithm to support
       mixed-PSK. Add an optional input PSA_KEY_DERIVATION_INPUT_OTHER_SECRET
       holding the other secret.
    * When MBEDTLS_PSA_CRYPTO_CONFIG is enabled, you may list the PSA crypto
      feature requirements in the file named by the new macro
      MBEDTLS_PSA_CRYPTO_CONFIG_FILE instead of the default psa/crypto_config.h.
      Furthermore you may name an additional file to include after the main
      file with the macro MBEDTLS_PSA_CRYPTO_USER_CONFIG_FILE.
    * Add the function mbedtls_x509_crt_has_ext_type() to access the ext types
      field within mbedtls_x509_crt context, as requested in #5585.
    * Add HKDF-Expand and HKDF-Extract as separate algorithms in the PSA API.
    * Add support for the ARMv8 SHA-2 acceleration instructions when building
      for Aarch64.
    * Add support for authentication of TLS 1.3 clients by TLS 1.3 servers.
    * Add support for server HelloRetryRequest message. The TLS 1.3 client is
      now capable of negotiating another shared secret if the one sent in its
      first ClientHello was not suitable to the server.
    * Add support for client-side TLS version negotiation. If both TLS 1.2 and
      TLS 1.3 protocols are enabled in the build of Mbed TLS, the TLS client now
      negotiates TLS 1.3 or TLS 1.2 with TLS servers.
    * Enable building of Mbed TLS with TLS 1.3 protocol support but without TLS
      1.2 protocol support.
    * Mbed TLS provides an implementation of a TLS 1.3 server (ephemeral key
      establishment only). See docs/architecture/tls13-support.md for a
      description of the support. The MBEDTLS_SSL_PROTO_TLS1_3 and
      MBEDTLS_SSL_SRV_C configuration options control this.
    * Add accessors to configure DN hints for certificate request:
      mbedtls_ssl_conf_dn_hints() and mbedtls_ssl_set_hs_dn_hints()
    * The configuration option MBEDTLS_USE_PSA_CRYPTO, which previously
      affected only a limited subset of crypto operations in TLS, X.509 and PK,
      now causes most of them to be done using PSA Crypto; see
      docs/use-psa-crypto.md for the list of exceptions.
    * The function mbedtls_pk_setup_opaque() now supports RSA key pairs as well.
      Opaque keys can now be used everywhere a private key is expected in the
      TLS and X.509 modules.
    * Opaque pre-shared keys for TLS, provisioned with
      mbedtls_ssl_conf_psk_opaque() or mbedtls_ssl_set_hs_psk_opaque(), which
      previously only worked for "pure" PSK key exchange, now can also be used
      for the "mixed" PSK key exchanges as well: ECDHE-PSK, DHE-PSK, RSA-PSK.
    * cmake now detects if it is being built as a sub-project, and in that case
      disables the target export/installation and package configuration.
    * Make USE_PSA_CRYPTO compatible with KEY_ID_ENCODES_OWNER. Fixes #5259.
    * Add example programs cipher_aead_demo.c, md_hmac_demo.c, aead_demo.c
      and hmac_demo.c, which use PSA and the md/cipher interfaces side
      by side in order to illustrate how the operation is performed in PSA.
      Addresses #5208.
 
 Security
    * Zeroize dynamically-allocated buffers used by the PSA Crypto key storage
      module before freeing them. These buffers contain secret key material, and
      could thus potentially leak the key through freed heap.
    * Fix potential memory leak inside mbedtls_ssl_cache_set() with
      an invalid session id length.
    * Add the platform function mbedtls_setbuf() to allow buffering to be
      disabled on stdio files, to stop secrets loaded from said files being
      potentially left in memory after file operations. Reported by
      Glenn Strauss.
    * Fix a potential heap buffer overread in TLS 1.2 server-side when
      MBEDTLS_USE_PSA_CRYPTO is enabled, an opaque key (created with
      mbedtls_pk_setup_opaque()) is provisioned, and a static ECDH ciphersuite
      is selected. This may result in an application crash or potentially an
      information leak.
    * Fix a buffer overread in DTLS ClientHello parsing in servers with
      MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE enabled. An unauthenticated client
      or a man-in-the-middle could cause a DTLS server to read up to 255 bytes
      after the end of the SSL input buffer. The buffer overread only happens
      when MBEDTLS_SSL_IN_CONTENT_LEN is less than a threshold that depends on
      the exact configuration: 258 bytes if using mbedtls_ssl_cookie_check(),
      and possibly up to 571 bytes with a custom cookie check function.
      Reported by the Cybeats PSI Team.
     * Fix a buffer overread in TLS 1.3 Certificate parsing. An unauthenticated
       client or server could cause an MbedTLS server or client to overread up
       to 64 kBytes of data and potentially overread the input buffer by that
       amount minus the size of the input buffer. As overread data undergoes
       various checks, the likelihood of reaching the boundary of the input
       buffer is rather small but increases as its size
       MBEDTLS_SSL_IN_CONTENT_LEN decreases.
    * Fix check of certificate key usage in TLS 1.3. The usage of the public key
      provided by a client or server certificate for authentication was not
      checked properly when validating the certificate. This could cause a
      client or server to be able to authenticate itself through a certificate
      to an Mbed TLS TLS 1.3 server or client while it does not own a proper
      certificate to do so.
 
 Bugfix
    * Declare or use PSA_WANT_ALG_CCM_STAR_NO_TAG following the general
      pattern for PSA_WANT_xxx symbols. Previously you had to specify
      PSA_WANT_ALG_CCM for PSA_ALG_CCM_STAR_NO_TAG.
    * Fix a memory leak if mbedtls_ssl_config_defaults() is called twice.
    * Fixed swap of client and server random bytes when exporting them alongside
      TLS 1.3 handshake and application traffic secret.
    * Fix several bugs (warnings, compiler and linker errors, test failures)
      in reduced configurations when MBEDTLS_USE_PSA_CRYPTO is enabled.
    * Fix a bug in (D)TLS curve negotiation: when MBEDTLS_USE_PSA_CRYPTO was
      enabled and an ECDHE-ECDSA or ECDHE-RSA key exchange was used, the
      client would fail to check that the curve selected by the server for
      ECDHE was indeed one that was offered. As a result, the client would
      accept any curve that it supported, even if that curve was not allowed
      according to its configuration. Fixes #5291.
    * The TLS 1.3 implementation is now compatible with the
      MBEDTLS_USE_PSA_CRYPTO configuration option.
    * Fix unit tests that used 0 as the file UID. This failed on some
      implementations of PSA ITS. Fixes #3838.
    * Fix mbedtls_ssl_get_version() not reporting TLSv1.3. Fixes #5406.
    * Fix API violation in mbedtls_md_process() test by adding a call to
      mbedtls_md_starts(). Fixes #2227.
    * Fix compile errors when MBEDTLS_HAVE_TIME is not defined. Add tests
      to catch bad uses of time.h.
    * Fix a race condition in out-of-source builds with CMake when generated data
      files are already present. Fixes #5374.
    * Fix the library search path when building a shared library with CMake
      on Windows.
    * Fix bug in the alert sending function mbedtls_ssl_send_alert_message()
      potentially leading to corrupted alert messages being sent in case
      the function needs to be re-called after initially returning
      MBEDTLS_SSL_WANT_WRITE. Fixes #1916.
    * In configurations with MBEDTLS_SSL_DTLS_CONNECTION_ID enabled but not
      MBEDTLS_DEBUG_C, DTLS handshakes using CID would crash due to a null
      pointer dereference. Fix this. Fixes #3998.
      The fix was released, but not announced, in Mbed TLS 3.1.0.
    * Fix incorrect documentation of mbedtls_x509_crt_profile. The previous
      documentation stated that the `allowed_pks` field applies to signatures
      only, but in fact it does apply to the public key type of the end entity
      certificate, too. Fixes #1992.
    * Fix undefined behavior in mbedtls_asn1_find_named_data(), where val is
      not NULL and val_len is zero.
    * Fix compilation error with mingw32. Fixed by Cameron Cawley in #4211.
    * Fix compilation error when using C++ Builder on Windows. Reported by
      Miroslav Mastny in #4015.
    * psa_raw_key_agreement() now returns PSA_ERROR_BUFFER_TOO_SMALL when
      applicable. Fixes #5735.
    * Fix a bug in the x25519 example program where the removal of
      MBEDTLS_ECDH_LEGACY_CONTEXT caused the program not to run. Fixes #4901 and
      #3191.
    * Fix a TLS 1.3 handshake failure when the peer Finished message has not
      been received yet when we first try to fetch it.
    * Encode X.509 dates before 1/1/2000 as UTCTime rather than
      GeneralizedTime. Fixes #5465.
    * Add mbedtls_x509_dn_get_next function to return the next relative DN in
      an X509 name, to allow walking the name list. Fixes #5431.
     * Fix order value of curve x448.
    * Fix string representation of DNs when outputting values containing commas
      and other special characters, conforming to RFC 1779. Fixes #769.
    * Silence a warning from GCC 12 in the selftest program. Fixes #5974.
    * Fix check_config.h to check that we have MBEDTLS_SSL_KEEP_PEER_CERTIFICATE
      when MBEDTLS_SSL_PROTO_TLS1_3 is specified, and make this and other
      dependencies explicit in the documentation. Fixes #5610.
    * Fix mbedtls_asn1_write_mpi() writing an incorrect encoding of 0.
    * Fix a TLS 1.3 handshake failure when the first attempt to send the client
      Finished message on the network cannot be satisfied. Fixes #5499.
    * Fix resource leaks in mbedtls_pk_parse_public_key() in low
      memory conditions.
    * Fix server connection identifier setting for outgoing encrypted records
      on DTLS 1.2 session resumption. After DTLS 1.2 session resumption with
      connection identifier, the Mbed TLS client now properly sends the server
      connection identifier in encrypted record headers. Fix #5872.
    * Fix a null pointer dereference when performing some operations on zero
      represented with 0 limbs (specifically mbedtls_mpi_mod_int() dividing
      by 2, and mbedtls_mpi_write_string() in base 2).
    * Fix record sizes larger than 16384 being sometimes accepted despite being
      non-compliant. This could not lead to a buffer overflow. In particular,
      application data size was already checked correctly.
    * Fix MBEDTLS_SVC_KEY_ID_GET_KEY_ID() and MBEDTLS_SVC_KEY_ID_GET_OWNER_ID()
      which have been broken, resulting in compilation errors, since Mbed TLS
      3.0.
    * Ensure that TLS 1.2 ciphersuite/certificate and key selection takes into
      account not just the type of the key (RSA vs EC) but also what it can
      actually do. Resolves #5831.
    * Fix CMake windows host detection, especially when cross compiling.
    * Fix an error in make where the absence of a generated file caused
      make to break on a clean checkout. Fixes #5340.
    * Work around an MSVC ARM64 compiler bug causing incorrect behaviour
      in mbedtls_mpi_exp_mod(). Reported by Tautvydas Žilys in #5467.
    * Removed the prompt to exit from all windows build programs, which was causing
      issues in CI/CD environments.
 
 Changes
    * The file library/psa_crypto_driver_wrappers.c is now generated
      from a template. In the future, the generation will support
      driver descriptions. For the time being, to customize this file,
      see docs/proposed/psa-driver-wrappers-codegen-migration-guide.md
    * Return PSA_ERROR_INVALID_ARGUMENT if the algorithm passed to one-shot
      AEAD functions is not an AEAD algorithm. This aligns them with the
      multipart functions, and the PSA Crypto API 1.1 specification.
    * In mbedtls_pk_parse_key(), if no password is provided, don't allocate a
      temporary variable on the heap. Suggested by Sergey Kanatov in #5304.
    * Assume source files are in UTF-8 when using MSVC with CMake.
    * Fix runtime library install location when building with CMake and MinGW.
      DLLs are now installed in the bin directory instead of lib.
    * cmake: Use GnuInstallDirs to customize install directories
      Replace custom LIB_INSTALL_DIR variable with standard CMAKE_INSTALL_LIBDIR
      variable. For backward compatibility, set CMAKE_INSTALL_LIBDIR if
      LIB_INSTALL_DIR is set.
    * Add a CMake option that enables static linking of the runtime library
      in Microsoft Visual C++ compiler. Contributed by Microplankton.
    * In CMake builds, add aliases for libraries so that the normal MbedTLS::*
      targets work when MbedTLS is built as a subdirectory. This allows the
      use of FetchContent, as requested in #5688.
 
 = mbed TLS 3.1.0 branch released 2021-12-17
 
 API changes
    * New error code for GCM: MBEDTLS_ERR_GCM_BUFFER_TOO_SMALL.
      Alternative GCM implementations are expected to verify
      the length of the provided output buffers and to return the
      MBEDTLS_ERR_GCM_BUFFER_TOO_SMALL in case the buffer length is too small.
    * You can configure groups for a TLS key exchange with the new function
      mbedtls_ssl_conf_groups(). It extends mbedtls_ssl_conf_curves().
    * Declare a number of structure fields as public: the fields of
      mbedtls_ecp_curve_info, the fields describing the result of ASN.1 and
      X.509 parsing, and finally the field fd of mbedtls_net_context on
      POSIX/Unix-like platforms.
 
 Requirement changes
    * Sign-magnitude and one's complement representations for signed integers are
      not supported. Two's complement is the only supported representation.
 
 New deprecations
    * Deprecate mbedtls_ssl_conf_curves() in favor of the more generic
      mbedtls_ssl_conf_groups().
 
 Removals
    * Remove the partial support for running unit tests via Greentea on Mbed OS,
      which had been unmaintained since 2018.
 
 Features
    * Enable support for Curve448 via the PSA API. Contributed by
      Archana Madhavan in #4626. Fixes #3399 and #4249.
    * The identifier of the CID TLS extension can be configured by defining
      MBEDTLS_TLS_EXT_CID at compile time.
    * Implement the PSA multipart AEAD interface, currently supporting
      ChaChaPoly and GCM.
    * Warn if errors from certain functions are ignored. This is currently
      supported on GCC-like compilers and on MSVC and can be configured through
      the macro MBEDTLS_CHECK_RETURN. The warnings are always enabled
      (where supported) for critical functions where ignoring the return
      value is almost always a bug. Enable the new configuration option
      MBEDTLS_CHECK_RETURN_WARNING to get warnings for other functions. This
      is currently implemented in the AES, DES and md modules, and will be
      extended to other modules in the future.
    * Add missing PSA macros declared by PSA Crypto API 1.0.0:
      PSA_ALG_IS_SIGN_HASH, PSA_ALG_NONE, PSA_HASH_BLOCK_LENGTH, PSA_KEY_ID_NULL.
    * Add support for CCM*-no-tag cipher to the PSA.
      Currently only 13-byte long IV's are supported.
      For decryption a minimum of 16-byte long input is expected.
      These restrictions may be subject to change.
    * Add new API mbedtls_ct_memcmp for constant time buffer comparison.
    * Add functions to get the IV and block size from cipher_info structs.
    * Add functions to check if a cipher supports variable IV or key size.
    * Add the internal implementation of and support for CCM to the PSA multipart
      AEAD interface.
    * Mbed TLS provides a minimum viable implementation of the TLS 1.3
      protocol. See docs/architecture/tls13-support.md for the definition of
      the TLS 1.3 Minimum Viable Product (MVP). The MBEDTLS_SSL_PROTO_TLS1_3
      configuration option controls the enablement of the support. The APIs
      mbedtls_ssl_conf_min_version() and mbedtls_ssl_conf_max_version() allow
      to select the 1.3 version of the protocol to establish a TLS connection.
    * Add PSA API definition for ARIA.
 
 Security
    * Zeroize several intermediate variables used to calculate the expected
      value when verifying a MAC or AEAD tag. This hardens the library in
      case the value leaks through a memory disclosure vulnerability. For
      example, a memory disclosure vulnerability could have allowed a
      man-in-the-middle to inject fake ciphertext into a DTLS connection.
    * In psa_aead_generate_nonce(), do not read back from the output buffer.
      This fixes a potential policy bypass or decryption oracle vulnerability
      if the output buffer is in memory that is shared with an untrusted
      application.
    * In psa_cipher_generate_iv() and psa_cipher_encrypt(), do not read back
      from the output buffer. This fixes a potential policy bypass or decryption
      oracle vulnerability if the output buffer is in memory that is shared with
      an untrusted application.
    * Fix a double-free that happened after mbedtls_ssl_set_session() or
      mbedtls_ssl_get_session() failed with MBEDTLS_ERR_SSL_ALLOC_FAILED
      (out of memory). After that, calling mbedtls_ssl_session_free()
      and mbedtls_ssl_free() would cause an internal session buffer to
      be free()'d twice.
 
 Bugfix
    * Stop using reserved identifiers as local variables. Fixes #4630.
    * The GNU makefiles invoke python3 in preference to python except on Windows.
      The check was accidentally not performed when cross-compiling for Windows
      on Linux. Fix this. Fixes #4774.
    * Prevent divide by zero if either of PSA_CIPHER_ENCRYPT_OUTPUT_SIZE() or
      PSA_CIPHER_UPDATE_OUTPUT_SIZE() were called using an asymmetric key type.
    * Fix a parameter set but unused in psa_crypto_cipher.c. Fixes #4935.
    * Don't use the obsolete header path sys/fcntl.h in unit tests.
      These header files cause compilation errors in musl.
      Fixes #4969.
    * Fix missing constraints on x86_64 and aarch64 assembly code
      for bignum multiplication that broke some bignum operations with
      (at least) Clang 12.
      Fixes #4116, #4786, #4917, #4962.
    * Fix mbedtls_cipher_crypt: AES-ECB when MBEDTLS_USE_PSA_CRYPTO is enabled.
    * Failures of alternative implementations of AES or DES single-block
      functions enabled with MBEDTLS_AES_ENCRYPT_ALT, MBEDTLS_AES_DECRYPT_ALT,
      MBEDTLS_DES_CRYPT_ECB_ALT or MBEDTLS_DES3_CRYPT_ECB_ALT were ignored.
      This does not concern the implementation provided with Mbed TLS,
      where this function cannot fail, or full-module replacements with
      MBEDTLS_AES_ALT or MBEDTLS_DES_ALT. Reported by Armelle Duboc in #1092.
    * Some failures of HMAC operations were ignored. These failures could only
      happen with an alternative implementation of the underlying hash module.
    * Fix the error returned by psa_generate_key() for a public key. Fixes #4551.
    * Fix compile-time or run-time errors in PSA
      AEAD functions when ChachaPoly is disabled. Fixes #5065.
    * Remove PSA'a AEAD finish/verify output buffer limitation for GCM.
      The requirement of minimum 15 bytes for output buffer in
      psa_aead_finish() and psa_aead_verify() does not apply to the built-in
      implementation of GCM.
    * Move GCM's update output buffer length verification from PSA AEAD to
      the built-in implementation of the GCM.
      The requirement for output buffer size to be equal or greater then
      input buffer size is valid only for the built-in implementation of GCM.
      Alternative GCM implementations can process whole blocks only.
    * Fix the build of sample programs when neither MBEDTLS_ERROR_C nor
      MBEDTLS_ERROR_STRERROR_DUMMY is enabled.
    * Fix PSA_ALG_RSA_PSS verification accepting an arbitrary salt length.
      This algorithm now accepts only the same salt length for verification
      that it produces when signing, as documented. Use the new algorithm
      PSA_ALG_RSA_PSS_ANY_SALT to accept any salt length. Fixes #4946.
    * The existing predicate macro name PSA_ALG_IS_HASH_AND_SIGN is now reserved
      for algorithm values that fully encode the hashing step, as per the PSA
      Crypto API specification. This excludes PSA_ALG_RSA_PKCS1V15_SIGN_RAW and
      PSA_ALG_ECDSA_ANY. The new predicate macro PSA_ALG_IS_SIGN_HASH covers
      all algorithms that can be used with psa_{sign,verify}_hash(), including
      these two.
    * Fix issue in Makefile on Linux with SHARED=1, that caused shared libraries
      not to list other shared libraries they need.
    * Fix a bug in mbedtls_gcm_starts() when the bit length of the iv
      exceeds 2^32. Fixes #4884.
    * Fix an uninitialized variable warning in test_suite_ssl.function with GCC
      version 11.
    * Fix the build when no SHA2 module is included. Fixes #4930.
    * Fix the build when only the bignum module is included. Fixes #4929.
    * Fix a potential invalid pointer dereference and infinite loop bugs in
      pkcs12 functions when the password is empty. Fix the documentation to
      better describe the inputs to these functions and their possible values.
      Fixes #5136.
    * The key usage flags PSA_KEY_USAGE_SIGN_MESSAGE now allows the MAC
      operations psa_mac_compute() and psa_mac_sign_setup().
    * The key usage flags PSA_KEY_USAGE_VERIFY_MESSAGE now allows the MAC
      operations psa_mac_verify() and psa_mac_verify_setup().
 
 Changes
     * Explicitly mark the fields mbedtls_ssl_session.exported and
       mbedtls_ssl_config.respect_cli_pref as private. This was an
       oversight during the run-up to the release of Mbed TLS 3.0.
       The fields were never intended to be public.
    * Implement multi-part CCM API.
      The multi-part functions: mbedtls_ccm_starts(), mbedtls_ccm_set_lengths(),
      mbedtls_ccm_update_ad(), mbedtls_ccm_update(), mbedtls_ccm_finish()
      were introduced in mbedTLS 3.0 release, however their implementation was
      postponed until now.
      Implemented functions support chunked data input for both CCM and CCM*
      algorithms.
    * Remove MBEDTLS_SSL_EXPORT_KEYS, making it always on and increasing the
      code size by about 80B on an M0 build. This option only gated an ability
      to set a callback, but was deemed unnecessary as it was yet another define
      to remember when writing tests, or test configurations. Fixes #4653.
    * Improve the performance of base64 constant-flow code. The result is still
      slower than the original non-constant-flow implementation, but much faster
      than the previous constant-flow implementation. Fixes #4814.
    * Ignore plaintext/ciphertext lengths for CCM*-no-tag operations.
      For CCM* encryption/decryption without authentication, input
      length will be ignored.
    * Indicate in the error returned if the nonce length used with
      ChaCha20-Poly1305 is invalid, and not just unsupported.
    * The mbedcrypto library includes a new source code module constant_time.c,
      containing various functions meant to resist timing side channel attacks.
      This module does not have a separate configuration option, and functions
      from this module will be included in the build as required. Currently
      most of the interface of this module is private and may change at any
      time.
    * The generated configuration-independent files are now automatically
      generated by the CMake build system on Unix-like systems. This is not
      yet supported when cross-compiling.
 
 = Mbed TLS 3.0.0 branch released 2021-07-07
 
 API changes
    * Remove HAVEGE module.
      The design of HAVEGE makes it unsuitable for microcontrollers. Platforms
      with a more complex CPU usually have an operating system interface that
      provides better randomness. Instead of HAVEGE, declare OS or hardware RNG
      interfaces with mbedtls_entropy_add_source() and/or use an entropy seed
      file created securely during device provisioning. See
      https://mbed-tls.readthedocs.io/en/latest/kb/how-to/add-entropy-sources-to-entropy-pool/ for
      more information.
    * Add missing const attributes to API functions.
    * Remove helpers for the transition from Mbed TLS 1.3 to Mbed TLS 2.0: the
      header compat-1.3.h and the script rename.pl.
    * Remove certs module from the API.
      Transfer keys and certificates embedded in the library to the test
      component. This contributes to minimizing library API and discourages
      users from using unsafe keys in production.
    * Move alt helpers and definitions.
      Various helpers and definitions available for use in alt implementations
      have been moved out of the include/ directory and into the library/
      directory. The files concerned are ecp_internal.h and rsa_internal.h
      which have also been renamed to ecp_internal_alt.h and rsa_alt_helpers.h
      respectively.
    * Move internal headers.
      Header files that were only meant for the library's internal use and
      were not meant to be used in application code have been moved out of
      the include/ directory. The headers concerned are bn_mul.h, aesni.h,
      padlock.h, entropy_poll.h and *_internal.h.
    * Drop support for parsing SSLv2 ClientHello
      (MBEDTLS_SSL_SRV_SUPPORT_SSLV2_CLIENT_HELLO).
    * Drop support for SSLv3 (MBEDTLS_SSL_PROTO_SSL3).
    * Drop support for TLS record-level compression (MBEDTLS_ZLIB_SUPPORT).
    * Drop support for RC4 TLS ciphersuites.
    * Drop support for single-DES ciphersuites.
    * Drop support for MBEDTLS_SSL_HW_RECORD_ACCEL.
    * Update AEAD output size macros to bring them in line with the PSA Crypto
      API version 1.0 spec. This version of the spec parameterizes them on the
      key type used, as well as the key bit-size in the case of
      PSA_AEAD_TAG_LENGTH.
    * Add configuration option MBEDTLS_X509_REMOVE_INFO which
      removes the mbedtls_x509_*_info(), mbedtls_debug_print_crt()
      as well as other functions and constants only used by
      those functions. This reduces the code footprint by
      several kB.
    * Remove SSL error codes `MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED`
      and `MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH` which are never
      returned from the public SSL API.
    * Remove `MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE` and return
      `MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL` instead.
    * The output parameter of mbedtls_sha512_finish, mbedtls_sha512,
      mbedtls_sha256_finish and mbedtls_sha256 now has a pointer type
      rather than array type. This removes spurious warnings in some compilers
      when outputting a SHA-384 or SHA-224 hash into a buffer of exactly
      the hash size.
    * Remove the MBEDTLS_TEST_NULL_ENTROPY config option. Fixes #4388.
    * The interface of the GCM module has changed to remove restrictions on
      how the input to multipart operations is broken down. mbedtls_gcm_finish()
      now takes extra output parameters for the last partial output block.
      mbedtls_gcm_update() now takes extra parameters for the output length.
      The software implementation always produces the full output at each
      call to mbedtls_gcm_update(), but alternative implementations activated
      by MBEDTLS_GCM_ALT may delay partial blocks to the next call to
      mbedtls_gcm_update() or mbedtls_gcm_finish(). Furthermore, applications
      no longer pass the associated data to mbedtls_gcm_starts(), but to the
      new function mbedtls_gcm_update_ad().
      These changes are backward compatible for users of the cipher API.
    * Replace MBEDTLS_SHA512_NO_SHA384 config option with MBEDTLS_SHA384_C.
      This separates config option enabling the SHA384 algorithm from option
      enabling the SHA512 algorithm. Fixes #4034.
    * Introduce MBEDTLS_SHA224_C.
      This separates config option enabling the SHA224 algorithm from option
      enabling SHA256.
    * The getter and setter API of the SSL session cache (used for
      session-ID based session resumption) has changed to that of
      a key-value store with keys being session IDs and values
      being opaque instances of `mbedtls_ssl_session`.
    * Remove the mode parameter from RSA operation functions. Signature and
      decryption functions now always use the private key and verification and
      encryption use the public key. Verification functions also no longer have
      RNG parameters.
    * Modify semantics of `mbedtls_ssl_conf_[opaque_]psk()`:
      In Mbed TLS 2.X, the API prescribes that later calls overwrite
      the effect of earlier calls. In Mbed TLS 3.0, calling
      `mbedtls_ssl_conf_[opaque_]psk()` more than once will fail,
      leaving the PSK that was configured first intact.
      Support for more than one PSK may be added in 3.X.
    * The function mbedtls_x509write_csr_set_extension() has an extra parameter
      which allows to mark an extension as critical. Fixes #4055.
    * For multi-part AEAD operations with the cipher module, calling
      mbedtls_cipher_finish() is now mandatory. Previously the documentation
      was unclear on this point, and this function happened to never do
      anything with the currently implemented AEADs, so in practice it was
      possible to skip calling it, which is no longer supported.
    * The option MBEDTLS_ECP_FIXED_POINT_OPTIM use pre-computed comb tables
      instead of computing tables in runtime. Thus, this option now increase
      code size, and it does not increase RAM usage in runtime anymore.
    * Remove the SSL APIs mbedtls_ssl_get_input_max_frag_len() and
      mbedtls_ssl_get_output_max_frag_len(), and add a new API
      mbedtls_ssl_get_max_in_record_payload(), complementing the existing
      mbedtls_ssl_get_max_out_record_payload().
      Uses of mbedtls_ssl_get_input_max_frag_len() and
      mbedtls_ssl_get_input_max_frag_len() should be replaced by
      mbedtls_ssl_get_max_in_record_payload() and
      mbedtls_ssl_get_max_out_record_payload(), respectively.
    * mbedtls_rsa_init() now always selects the PKCS#1v1.5 encoding for an RSA
      key. To use an RSA key with PSS or OAEP, call mbedtls_rsa_set_padding()
      after initializing the context. mbedtls_rsa_set_padding() now returns an
      error if its parameters are invalid.
    * Replace MBEDTLS_SSL_SRV_RESPECT_CLIENT_PREFERENCE by a runtime
      configuration function mbedtls_ssl_conf_preference_order(). Fixes #4398.
    * Instead of accessing the len field of a DHM context, which is no longer
      supported, use the new function mbedtls_dhm_get_len() .
    * In modules that implement cryptographic hash functions, many functions
      mbedtls_xxx() now return int instead of void, and the corresponding
      function mbedtls_xxx_ret() which was identical except for returning int
      has been removed. This also concerns mbedtls_xxx_drbg_update(). See the
      migration guide for more information. Fixes #4212.
    * For all functions that take a random number generator (RNG) as a
      parameter, this parameter is now mandatory (that is, NULL is not an
      acceptable value). Functions which previously accepted NULL and now
      reject it are: the X.509 CRT and CSR writing functions; the PK and RSA
      sign and decrypt function; mbedtls_rsa_private(); the functions
      in DHM and ECDH that compute the shared secret; the scalar multiplication
      functions in ECP.
    * The following functions now require an RNG parameter:
      mbedtls_ecp_check_pub_priv(), mbedtls_pk_check_pair(),
      mbedtls_pk_parse_key(), mbedtls_pk_parse_keyfile().
    * mbedtls_ssl_conf_export_keys_ext_cb() and
      mbedtls_ssl_conf_export_keys_cb() have been removed and
      replaced by a new API mbedtls_ssl_set_export_keys_cb().
      Raw keys and IVs are no longer passed to the callback.
      Further, callbacks now receive an additional parameter
      indicating the type of secret that's being exported,
      paving the way for the larger number of secrets
      in TLS 1.3. Finally, the key export callback and
      context are now connection-specific.
    * Signature functions in the RSA and PK modules now require the hash
      length parameter to be the size of the hash input. For RSA signatures
      other than raw PKCS#1 v1.5, this must match the output size of the
      specified hash algorithm.
    * The functions mbedtls_pk_sign(), mbedtls_pk_sign_restartable(),
      mbedtls_ecdsa_write_signature() and
      mbedtls_ecdsa_write_signature_restartable() now take an extra parameter
      indicating the size of the output buffer for the signature.
    * Implement one-shot cipher functions, psa_cipher_encrypt and
      psa_cipher_decrypt, according to the PSA Crypto API 1.0.0
      specification.
    * Direct access to fields of structures declared in public headers is no
      longer supported except for fields that are documented public. Use accessor
      functions instead. For more information, see the migration guide entry
      "Most structure fields are now private".
    * mbedtls_ssl_get_session_pointer() has been removed, and
      mbedtls_ssl_{set,get}_session() may now only be called once for any given
      SSL context.
 
 Default behavior changes
    * Enable by default the functionalities which have no reason to be disabled.
      They are: ARIA block cipher, CMAC mode, elliptic curve J-PAKE library and
      Key Wrapping mode as defined in NIST SP 800-38F. Fixes #4036.
    * Some default policies for X.509 certificate verification and TLS have
      changed: curves and hashes weaker than 255 bits are no longer accepted
      by default. The default order in TLS now favors faster curves over larger
      curves.
 
 Requirement changes
    * The library now uses the %zu format specifier with the printf() family of
      functions, so requires a toolchain that supports it. This change does not
      affect the maintained LTS branches, so when contributing changes please
      bear this in mind and do not add them to backported code.
    * If you build the development version of Mbed TLS, rather than an official
      release, some configuration-independent files are now generated at build
      time rather than checked into source control. This includes some library
      source files as well as the Visual Studio solution. Perl, Python 3 and a
      C compiler for the host platform are required. See “Generated source files
      in the development branch” in README.md for more information.
    * Refresh the minimum supported versions of tools to build the
      library. CMake versions older than 3.10.2 and Python older
      than 3.6 are no longer supported.
 
 Removals
    * Remove the MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_CERTIFICATES
      compile-time option, which was off by default. Users should not trust
      certificates signed with SHA-1 due to the known attacks against SHA-1.
      If needed, SHA-1 certificates can still be verified by using a custom
      verification profile.
    * Removed deprecated things in psa/crypto_compat.h. Fixes #4284
    * Removed deprecated functions from hashing modules. Fixes #4280.
    * Remove PKCS#11 library wrapper. PKCS#11 has limited functionality,
      lacks automated tests and has scarce documentation. Also, PSA Crypto
      provides a more flexible private key management.
      More details on PCKS#11 wrapper removal can be found in the mailing list
      https://lists.trustedfirmware.org/pipermail/mbed-tls/2020-April/000024.html
    * Remove deprecated error codes. Fix #4283
    * Remove MBEDTLS_ENABLE_WEAK_CIPHERSUITES configuration option. Fixes #4416.
    * Remove the MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_CERTIFICATES
      compile-time option. This option has been inactive for a long time.
      Please use the `lifetime` parameter of `mbedtls_ssl_ticket_setup()`
      instead.
    * Remove the following deprecated functions and constants of hex-encoded
      primes based on RFC 5114 and RFC 3526 from library code and tests:
      mbedtls_aes_encrypt(), mbedtls_aes_decrypt(), mbedtls_mpi_is_prime(),
      mbedtls_cipher_auth_encrypt(), mbedtls_cipher_auth_decrypt(),
      mbedtls_ctr_drbg_update(), mbedtls_hmac_drbg_update(),
      mbedtls_ecdsa_write_signature_det(), mbedtls_ecdsa_sign_det(),
      mbedtls_ssl_conf_dh_param(), mbedtls_ssl_get_max_frag_len(),
      MBEDTLS_DHM_RFC5114_MODP_2048_P, MBEDTLS_DHM_RFC5114_MODP_2048_G,
      MBEDTLS_DHM_RFC3526_MODP_2048_P, MBEDTLS_DHM_RFC3526_MODP_2048_G,
      MBEDTLS_DHM_RFC3526_MODP_3072_P, MBEDTLS_DHM_RFC3526_MODP_3072_G,
      MBEDTLS_DHM_RFC3526_MODP_4096_P, MBEDTLS_DHM_RFC3526_MODP_4096_G.
      Remove the deprecated file: include/mbedtls/net.h. Fixes #4282.
    * Remove MBEDTLS_SSL_MAX_CONTENT_LEN configuration option, since
      MBEDTLS_SSL_IN_CONTENT_LEN and MBEDTLS_SSL_OUT_CONTENT_LEN replace
      it. Fixes #4362.
    * Remove the MBEDTLS_SSL_RECORD_CHECKING option and enable by default its
      previous action. Fixes #4361.
    * Remove support for TLS 1.0, TLS 1.1 and DTLS 1.0, as well as support for
      CBC record splitting, fallback SCSV, and the ability to configure
      ciphersuites per version, which are no longer relevant. This removes the
      configuration options MBEDTLS_SSL_PROTO_TLS1,
      MBEDTLS_SSL_PROTO_TLS1_1, MBEDTLS_SSL_CBC_RECORD_SPLITTING and
      MBEDTLS_SSL_FALLBACK_SCSV as well as the functions
      mbedtls_ssl_conf_cbc_record_splitting(),
      mbedtls_ssl_get_key_exchange_md_ssl_tls(), mbedtls_ssl_conf_fallback(),
      and mbedtls_ssl_conf_ciphersuites_for_version(). Fixes #4286.
    * The RSA module no longer supports private-key operations with the public
      key and vice versa.
    * Remove the MBEDTLS_SSL_DTLS_BADMAC_LIMIT config.h option. Fixes #4403.
    * Remove all the 3DES ciphersuites:
      MBEDTLS_TLS_DHE_PSK_WITH_3DES_EDE_CBC_SHA,
      MBEDTLS_TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA,
      MBEDTLS_TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA,
      MBEDTLS_TLS_ECDHE_PSK_WITH_3DES_EDE_CBC_SHA,
      MBEDTLS_TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
      MBEDTLS_TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA,
      MBEDTLS_TLS_PSK_WITH_3DES_EDE_CBC_SHA,
      MBEDTLS_TLS_RSA_PSK_WITH_3DES_EDE_CBC_SHA,
      MBEDTLS_TLS_RSA_WITH_3DES_EDE_CBC_SHA. Remove the
      MBEDTLS_REMOVE_3DES_CIPHERSUITES option which is no longer relevant.
      Fixes #4367.
    * Remove the MBEDTLS_X509_ALLOW_EXTENSIONS_NON_V3 option and let the code
      behave as if it was always disabled. Fixes #4386.
    * Remove MBEDTLS_ECDH_LEGACY_CONTEXT config option since this was purely for
      backward compatibility which is no longer supported. Addresses #4404.
    * Remove the following macros: MBEDTLS_CHECK_PARAMS,
      MBEDTLS_CHECK_PARAMS_ASSERT, MBEDTLS_PARAM_FAILED,
      MBEDTLS_PARAM_FAILED_ALT. Fixes #4313.
    * Remove the  MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION config.h
      option. The mbedtls_x509_crt_parse_der_with_ext_cb() is the way to go for
      migration path. Fixes #4378.
    * Remove the MBEDTLS_X509_CHECK_KEY_USAGE and
      MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE config.h options and let the code
      behave as if they were always enabled. Fixes #4405.
    * MBEDTLS_ECP_MAX_BITS is no longer a configuration option because it is
      now determined automatically based on supported curves.
    * Remove the following functions: mbedtls_timing_self_test(),
      mbedtls_hardclock_poll(), mbedtls_timing_hardclock() and
      mbedtls_set_alarm(). Fixes #4083.
    * The configuration option MBEDTLS_ECP_NO_INTERNAL_RNG has been removed as
      it no longer had any effect.
    * Remove all support for MD2, MD4, RC4, Blowfish and XTEA. This removes the
      corresponding modules and all their APIs and related configuration
      options. Fixes #4084.
    * Remove MBEDTLS_SSL_TRUNCATED_HMAC and also remove
      MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT config option. Users are better served by
      using a CCM-8 ciphersuite than a CBC ciphersuite with truncated HMAC.
      See issue #4341 for more details.
    * Remove the compile-time option
      MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_KEY_EXCHANGE.
 
 Features
    * Add mbedtls_rsa_rsassa_pss_sign_ext() function allowing to generate a
      signature with a specific salt length. This function allows to validate
      test cases provided in the NIST's CAVP test suite. Contributed by Cédric
      Meuter in PR #3183.
    * Added support for built-in driver keys through the PSA opaque crypto
      driver interface. Refer to the documentation of
      MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS for more information.
    * Implement psa_sign_message() and psa_verify_message().
    * The multi-part GCM interface (mbedtls_gcm_update() or
      mbedtls_cipher_update()) no longer requires the size of partial inputs to
      be a multiple of 16.
    * The multi-part GCM interface now supports chunked associated data through
      multiple calls to mbedtls_gcm_update_ad().
    * The new function mbedtls_mpi_random() generates a random value in a
      given range uniformly.
    * Alternative implementations of the AES, DHM, ECJPAKE, ECP, RSA and timing
      modules had undocumented constraints on their context types. These
      constraints have been relaxed.
      See docs/architecture/alternative-implementations.md for the remaining
      constraints.
    * The new functions mbedtls_dhm_get_len() and mbedtls_dhm_get_bitlen()
      query the size of the modulus in a Diffie-Hellman context.
    * The new function mbedtls_dhm_get_value() copy a field out of a
      Diffie-Hellman context.
    * Use the new function mbedtls_ecjpake_set_point_format() to select the
      point format for ECJPAKE instead of accessing the point_format field
      directly, which is no longer supported.
    * Implement psa_mac_compute() and psa_mac_verify() as defined in the
      PSA Cryptograpy API 1.0.0 specification.
 
 Security
    * Fix a bias in the generation of finite-field Diffie-Hellman-Merkle (DHM)
      private keys and of blinding values for DHM and elliptic curves (ECP)
      computations. Reported by FlorianF89 in #4245.
    * Fix a potential side channel vulnerability in ECDSA ephemeral key generation.
      An adversary who is capable of very precise timing measurements could
      learn partial information about the leading bits of the nonce used for the
      signature, allowing the recovery of the private key after observing a
      large number of signature operations. This completes a partial fix in
      Mbed TLS 2.20.0.
    * Fix an issue where an adversary with access to precise enough information
      about memory accesses (typically, an untrusted operating system attacking
      a secure enclave) could recover an RSA private key after observing the
      victim performing a single private-key operation. Found and reported by
      Zili KOU, Wenjian HE, Sharad Sinha, and Wei ZHANG.
    * Fix an issue where an adversary with access to precise enough timing
      information (typically, a co-located process) could recover a Curve25519
      or Curve448 static ECDH key after inputting a chosen public key and
      observing the victim performing the corresponding private-key operation.
      Found and reported by Leila Batina, Lukas Chmielewski, Björn Haase, Niels
      Samwel and Peter Schwabe.
 
 Bugfix
    * Fix premature fopen() call in mbedtls_entropy_write_seed_file which may
      lead to the seed file corruption in case if the path to the seed file is
      equal to MBEDTLS_PLATFORM_STD_NV_SEED_FILE. Contributed by Victor
      Krasnoshchok in #3616.
    * PSA functions creating a key now return PSA_ERROR_INVALID_ARGUMENT rather
      than PSA_ERROR_INVALID_HANDLE when the identifier specified for the key
      to create is not valid, bringing them in line with version 1.0.0 of the
      specification. Fix #4271.
    * Add printf function attributes to mbedtls_debug_print_msg to ensure we
      get printf format specifier warnings.
    * PSA functions other than psa_open_key now return PSA_ERROR_INVALID_HANDLE
      rather than PSA_ERROR_DOES_NOT_EXIST for an invalid handle, bringing them
      in line with version 1.0.0 of the specification. Fix #4162.
    * Fix a bug in ECDSA that would cause it to fail when the hash is all-bits
      zero. Fixes #1792
    * Fix some cases in the bignum module where the library constructed an
      unintended representation of the value 0 which was not processed
      correctly by some bignum operations. This could happen when
      mbedtls_mpi_read_string() was called on "-0", or when
      mbedtls_mpi_mul_mpi() and mbedtls_mpi_mul_int() was called with one of
      the arguments being negative and the other being 0. Fixes #4643.
    * Fix a compilation error when MBEDTLS_ECP_RANDOMIZE_MXZ_ALT is
      defined. Fixes #4217.
    * Fix an incorrect error code when parsing a PKCS#8 private key.
    * In a TLS client, enforce the Diffie-Hellman minimum parameter size
      set with mbedtls_ssl_conf_dhm_min_bitlen() precisely. Before, the
      minimum size was rounded down to the nearest multiple of 8.
    * In library/net_sockets.c, _POSIX_C_SOURCE and _XOPEN_SOURCE are
      defined to specific values.  If the code is used in a context
      where these are already defined, this can result in a compilation
      error.  Instead, assume that if they are defined, the values will
      be adequate to build Mbed TLS.
    * With MBEDTLS_PSA_CRYPTO_C disabled, some functions were getting built
      nonetheless, resulting in undefined reference errors when building a
      shared library. Reported by Guillermo Garcia M. in #4411.
    * The cipher suite TLS-RSA-WITH-CAMELLIA-256-GCM-SHA384 was not available
      when SHA-1 was disabled and was offered when SHA-1 was enabled but SHA-384
      was disabled. Fix the dependency. Fixes #4472.
    * Do not offer SHA384 cipher suites when SHA-384 is disabled. Fixes #4499.
    * Fix test suite code on platforms where int32_t is not int, such as
      Arm Cortex-M. Fixes #4530.
    * Fix some issues affecting MBEDTLS_ARIA_ALT implementations: a misplaced
      directive in a header and a missing initialization in the self-test.
    * Fix a missing initialization in the Camellia self-test, affecting
      MBEDTLS_CAMELLIA_ALT implementations.
    * Restore the ability to configure PSA via Mbed TLS options to support RSA
      key pair operations but exclude RSA key generation. When MBEDTLS_GENPRIME
      is not defined PSA will no longer attempt to use mbedtls_rsa_gen_key().
      Fixes #4512.
    * Fix a regression introduced in 2.24.0 which broke (D)TLS CBC ciphersuites
      (when the encrypt-then-MAC extension is not in use) with some ALT
      implementations of the underlying hash (SHA-1, SHA-256, SHA-384), causing
      the affected side to wrongly reject valid messages. Fixes #4118.
    * Remove outdated check-config.h check that prevented implementing the
      timing module on Mbed OS. Fixes #4633.
    * Fix PSA_ALG_TLS12_PRF and PSA_ALG_TLS12_PSK_TO_MS being too permissive
      about missing inputs.
    * Fix mbedtls_net_poll() and mbedtls_net_recv_timeout() often failing with
      MBEDTLS_ERR_NET_POLL_FAILED on Windows. Fixes #4465.
    * Fix a resource leak in a test suite with an alternative AES
      implementation. Fixes #4176.
    * Fix a crash in mbedtls_mpi_debug_mpi on a bignum having 0 limbs. This
      could notably be triggered by setting the TLS debug level to 3 or above
      and using a Montgomery curve for the key exchange. Reported by lhuang04
      in #4578. Fixes #4608.
    * psa_verify_hash() was relying on implementation-specific behavior of
      mbedtls_rsa_rsassa_pss_verify() and was causing failures in some _ALT
      implementations. This reliance is now removed. Fixes #3990.
    * Disallow inputs of length different from the corresponding hash when
      signing or verifying with PSA_ALG_RSA_PSS (The PSA Crypto API mandates
      that PSA_ALG_RSA_PSS uses the same hash throughout the algorithm.)
    * Fix a null pointer dereference when mbedtls_mpi_exp_mod() was called with
      A=0 represented with 0 limbs. Up to and including Mbed TLS 2.26, this bug
      could not be triggered by code that constructed A with one of the
      mbedtls_mpi_read_xxx functions (including in particular TLS code) since
      those always built an mpi object with at least one limb.
      Credit to OSS-Fuzz. Fixes #4641.
    * Fix mbedtls_mpi_gcd(G,A,B) when the value of B is zero. This had no
      effect on Mbed TLS's internal use of mbedtls_mpi_gcd(), but may affect
      applications that call mbedtls_mpi_gcd() directly. Fixes #4642.
    * The PSA API no longer allows the creation or destruction of keys with a
      read-only lifetime. The persistence level PSA_KEY_PERSISTENCE_READ_ONLY
      can now only be used as intended, for keys that cannot be modified through
      normal use of the API.
    * When MBEDTLS_PSA_CRYPTO_SPM is enabled, crypto_spe.h was not included
      in all the right places. Include it from crypto_platform.h, which is
      the natural place. Fixes #4649.
    * Fix which alert is sent in some cases to conform to the
      applicable RFC: on an invalid Finished message value, an
      invalid max_fragment_length extension, or an
      unsupported extension used by the server.
    * Correct (change from 12 to 13 bytes) the value of the macro describing the
      maximum nonce length returned by psa_aead_generate_nonce().
 
 Changes
    * Fix the setting of the read timeout in the DTLS sample programs.
    * Add extra printf compiler warning flags to builds.
    * Fix memsan build false positive in x509_crt.c with clang 11
    * Alternative implementations of CMAC may now opt to not support 3DES as a
      CMAC block cipher, and still pass the CMAC self test.
    * Remove the AES sample application programs/aes/aescrypt2 which shows
      bad cryptographic practice. Fix #1906.
    * Remove configs/config-psa-crypto.h, which no longer had any intended
      differences from the default configuration, but had accidentally diverged.
    * When building the test suites with GNU make, invoke python3 or python, not
      python2, which is no longer supported upstream.
    * fix build failure on MinGW toolchain when __USE_MING_ANSI_STDIO is on.
      When that flag is on, standard GNU C printf format specifiers
      should be used.
    * Replace MBEDTLS_SSL_CID_PADDING_GRANULARITY and
      MBEDTLS_SSL_TLS1_3_PADDING_GRANULARITY with a new single unified option
      MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY. Fixes #4335.
    * Reduce the default value of MBEDTLS_ECP_WINDOW_SIZE. This reduces RAM usage
      during ECC operations at a negligible performance cost.
    * mbedtls_mpi_read_binary(), mbedtls_mpi_read_binary_le() and
      mbedtls_mpi_read_string() now construct an mbedtls_mpi object with 0 limbs
      when their input has length 0. Note that this is an implementation detail
      and can change at any time, so this change should be transparent, but it
      may result in mbedtls_mpi_write_binary() or mbedtls_mpi_write_string()
      now writing an empty string where it previously wrote one or more
      zero digits when operating from values constructed with an mpi_read
      function and some mpi operations.
    * Add CMake package config generation for CMake projects consuming Mbed TLS.
    * config.h has been split into build_info.h and mbedtls_config.h
      build_info.h is intended to be included from C code directly, while
      mbedtls_config.h is intended to be edited by end users wishing to
      change the build configuration, and should generally only be included from
      build_info.h.
    * The handling of MBEDTLS_CONFIG_FILE has been moved into build_info.h.
    * A config file version symbol, MBEDTLS_CONFIG_VERSION was introduced.
      Defining it to a particular value will ensure that Mbed TLS interprets
      the config file in a way that's compatible with the config file format
      used by the Mbed TLS release whose MBEDTLS_VERSION_NUMBER has the same
      value.
      The only value supported by Mbed TLS 3.0.0 is 0x03000000.
    * Various changes to which alert and/or error code may be returned
    * during the TLS handshake.
    * Implicitly add PSA_KEY_USAGE_SIGN_MESSAGE key usage policy flag when
      PSA_KEY_USAGE_SIGN_HASH flag is set and PSA_KEY_USAGE_VERIFY_MESSAGE flag
      when PSA_KEY_USAGE_VERIFY_HASH flag is set. This usage flag extension
      is also applied when loading a key from storage.
 
 = mbed TLS 2.26.0 branch released 2021-03-08
 
 API changes
    * Renamed the PSA Crypto API output buffer size macros to bring them in line
      with version 1.0.0 of the specification.
    * The API glue function mbedtls_ecc_group_of_psa() now takes the curve size
      in bits rather than bytes, with an additional flag to indicate if the
      size may have been rounded up to a whole number of bytes.
    * Renamed the PSA Crypto API AEAD tag length macros to bring them in line
      with version 1.0.0 of the specification.
 
 Default behavior changes
    * In mbedtls_rsa_context objects, the ver field was formerly documented
      as always 0. It is now reserved for internal purposes and may take
      different values.
 
 New deprecations
    * PSA_KEY_EXPORT_MAX_SIZE, PSA_HASH_SIZE, PSA_MAC_FINAL_SIZE,
      PSA_BLOCK_CIPHER_BLOCK_SIZE, PSA_MAX_BLOCK_CIPHER_BLOCK_SIZE and
      PSA_ALG_TLS12_PSK_TO_MS_MAX_PSK_LEN have been renamed, and the old names
      deprecated.
    * PSA_ALG_AEAD_WITH_DEFAULT_TAG_LENGTH and PSA_ALG_AEAD_WITH_TAG_LENGTH
      have been renamed, and the old names deprecated.
 
 Features
    * The PSA crypto subsystem can now use HMAC_DRBG instead of CTR_DRBG.
      CTR_DRBG is used by default if it is available, but you can override
      this choice by setting MBEDTLS_PSA_HMAC_DRBG_MD_TYPE at compile time.
      Fix #3354.
    * Automatic fallback to a software implementation of ECP when
      MBEDTLS_ECP_xxx_ALT accelerator hooks are in use can now be turned off
      through setting the new configuration flag MBEDTLS_ECP_NO_FALLBACK.
    * The PSA crypto subsystem can now be configured to use less static RAM by
      tweaking the setting for the maximum amount of keys simultaneously in RAM.
      MBEDTLS_PSA_KEY_SLOT_COUNT sets the maximum number of volatile keys that
      can exist simultaneously. It has a sensible default if not overridden.
    * Partial implementation of the PSA crypto driver interface: Mbed TLS can
      now use an external random generator instead of the library's own
      entropy collection and DRBG code. Enable MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG
      and see the documentation of mbedtls_psa_external_get_random() for details.
    * Applications using both mbedtls_xxx and psa_xxx functions (for example,
      applications using TLS and MBEDTLS_USE_PSA_CRYPTO) can now use the PSA
      random generator with mbedtls_xxx functions. See the documentation of
      mbedtls_psa_get_random() for details.
    * In the PSA API, the policy for a MAC or AEAD algorithm can specify a
      minimum MAC or tag length thanks to the new wildcards
      PSA_ALG_AT_LEAST_THIS_LENGTH_MAC and
      PSA_ALG_AEAD_WITH_AT_LEAST_THIS_LENGTH_TAG.
 
 Security
    * Fix a security reduction in CTR_DRBG when the initial seeding obtained a
      nonce from entropy. Applications were affected if they called
      mbedtls_ctr_drbg_set_nonce_len(), if they called
      mbedtls_ctr_drbg_set_entropy_len() with a size that was 3/2 times the key
      length, or when the entropy module uses SHA-256 and CTR_DRBG uses AES-256.
      In such cases, a random nonce was necessary to achieve the advertised
      security strength, but the code incorrectly used a constant instead of
      entropy from the nonce.
      Found by John Stroebel in #3819 and fixed in #3973.
    * Fix a buffer overflow in mbedtls_mpi_sub_abs() when calculating
      |A| - |B| where |B| is larger than |A| and has more limbs (so the
      function should return MBEDTLS_ERR_MPI_NEGATIVE_VALUE). Only
      applications calling mbedtls_mpi_sub_abs() directly are affected:
      all calls inside the library were safe since this function is
      only called with |A| >= |B|. Reported by Guido Vranken in #4042.
    * Fix an errorneous estimation for an internal buffer in
      mbedtls_pk_write_key_pem(). If MBEDTLS_MPI_MAX_SIZE is set to an odd
      value the function might fail to write a private RSA keys of the largest
      supported size.
      Found by Daniel Otte, reported in #4093 and fixed in #4094.
    * Fix a stack buffer overflow with mbedtls_net_poll() and
      mbedtls_net_recv_timeout() when given a file descriptor that is
      beyond FD_SETSIZE. Reported by FigBug in #4169.
    * Guard against strong local side channel attack against base64 tables by
      making access aceess to them use constant flow code.
 
 Bugfix
    * Fix use-after-scope error in programs/ssl/ssl_client2.c and ssl_server2.c
    * Fix memory leak that occured when calling psa_close_key() on a
      wrapped key with MBEDTLS_PSA_CRYPTO_SE_C defined.
    * Fix an incorrect error code if an RSA private operation glitched.
    * Fix a memory leak in an error case in psa_generate_derived_key_internal().
    * Fix a resource leak in CTR_DRBG and HMAC_DRBG when MBEDTLS_THREADING_C
      is enabled, on platforms where initializing a mutex allocates resources.
      This was a regression introduced in the previous release. Reported in
      #4017, #4045 and #4071.
    * Ensure that calling mbedtls_rsa_free() or mbedtls_entropy_free()
      twice is safe. This happens for RSA when some Mbed TLS library functions
      fail. Such a double-free was not safe when MBEDTLS_THREADING_C was
      enabled on platforms where freeing a mutex twice is not safe.
    * Fix a resource leak in a bad-arguments case of mbedtls_rsa_gen_key()
      when MBEDTLS_THREADING_C is enabled on platforms where initializing
      a mutex allocates resources.
    * Fixes a bug where, if the library was configured to include support for
      both the old SE interface and the new PSA driver interface, external keys were
      not loaded from storage. This was fixed by #3996.
    * This change makes 'mbedtls_x509write_crt_set_basic_constraints'
      consistent with RFC 5280 4.2.1.9 which says: "Conforming CAs MUST
      include this extension in all CA certificates that contain public keys
      used to validate digital signatures on certificates and MUST mark the
      extension as critical in such certificates." Previous to this change,
      the extension was always marked as non-critical. This was fixed by
      #3698.
 
 Changes
    * A new library C file psa_crypto_client.c has been created to contain
      the PSA code needed by a PSA crypto client when the PSA crypto
      implementation is not included into the library.
    * On recent enough versions of FreeBSD and DragonFlyBSD, the entropy module
      now uses the getrandom syscall instead of reading from /dev/urandom.
 
 = mbed TLS 2.25.0 branch released 2020-12-11
 
 API changes
    * The numerical values of the PSA Crypto API macros have been updated to
      conform to version 1.0.0 of the specification.
    * PSA_ALG_STREAM_CIPHER replaces PSA_ALG_CHACHA20 and PSA_ALG_ARC4.
      The underlying stream cipher is determined by the key type
      (PSA_KEY_TYPE_CHACHA20 or PSA_KEY_TYPE_ARC4).
    * The functions mbedtls_cipher_auth_encrypt() and
      mbedtls_cipher_auth_decrypt() no longer accept NIST_KW contexts,
      as they have no way to check if the output buffer is large enough.
      Please use mbedtls_cipher_auth_encrypt_ext() and
      mbedtls_cipher_auth_decrypt_ext() instead. Credit to OSS-Fuzz and
      Cryptofuzz. Fixes #3665.
 
 Requirement changes
    * Update the minimum required CMake version to 2.8.12.  This silences a
      warning on CMake 3.19.0. #3801
 
 New deprecations
    * PSA_ALG_CHACHA20 and PSA_ALG_ARC4 have been deprecated.
      Use PSA_ALG_STREAM_CIPHER instead.
    * The functions mbedtls_cipher_auth_encrypt() and
      mbedtls_cipher_auth_decrypt() are deprecated in favour of the new
      functions mbedtls_cipher_auth_encrypt_ext() and
      mbedtls_cipher_auth_decrypt_ext(). Please note that with AEAD ciphers,
      these new functions always append the tag to the ciphertext, and include
      the tag in the ciphertext length.
 
 Features
    * Partial implementation of the new PSA Crypto accelerator APIs. (Symmetric
      ciphers, asymmetric signing/verification and key generation, validate_key
      entry point, and export_public_key interface.)
    * Add support for ECB to the PSA cipher API.
    * In PSA, allow using a key declared with a base key agreement algorithm
      in combined key agreement and derivation operations, as long as the key
      agreement algorithm in use matches the algorithm the key was declared with.
      This is currently non-standard behaviour, but expected to make it into a
      future revision of the PSA Crypto standard.
    * Add MBEDTLS_TARGET_PREFIX CMake variable, which is prefixed to the mbedtls,
      mbedcrypto, mbedx509 and apidoc CMake target names. This can be used by
      external CMake projects that include this one to avoid CMake target name
      clashes.  The default value of this variable is "", so default target names
      are unchanged.
    * Add support for DTLS-SRTP as defined in RFC 5764. Contributed by Johan
      Pascal, improved by Ron Eldor.
    * In the PSA API, it is no longer necessary to open persistent keys:
      operations now accept the key identifier. The type psa_key_handle_t is now
      identical to psa_key_id_t instead of being platform-defined. This bridges
      the last major gap to compliance with the PSA Cryptography specification
      version 1.0.0. Opening persistent keys is still supported for backward
      compatibility, but will be deprecated and later removed in future
      releases.
    * PSA_AEAD_NONCE_LENGTH, PSA_AEAD_NONCE_MAX_SIZE, PSA_CIPHER_IV_LENGTH and
      PSA_CIPHER_IV_MAX_SIZE macros have been added as defined in version
      1.0.0 of the PSA Crypto API specification.
 
 Security
    * The functions mbedtls_cipher_auth_encrypt() and
      mbedtls_cipher_auth_decrypt() would write past the minimum documented
      size of the output buffer when used with NIST_KW. As a result, code using
      those functions as documented with NIST_KW could have a buffer overwrite
      of up to 15 bytes, with consequences ranging up to arbitrary code
      execution depending on the location of the output buffer.
    * Limit the size of calculations performed by mbedtls_mpi_exp_mod to
      MBEDTLS_MPI_MAX_SIZE to prevent a potential denial of service when
      generating Diffie-Hellman key pairs. Credit to OSS-Fuzz.
    * A failure of the random generator was ignored in mbedtls_mpi_fill_random(),
      which is how most uses of randomization in asymmetric cryptography
      (including key generation, intermediate value randomization and blinding)
      are implemented. This could cause failures or the silent use of non-random
      values. A random generator can fail if it needs reseeding and cannot not
      obtain entropy, or due to an internal failure (which, for Mbed TLS's own
      CTR_DRBG or HMAC_DRBG, can only happen due to a misconfiguration).
    * Fix a compliance issue whereby we were not checking the tag on the
      algorithm parameters (only the size) when comparing the signature in the
      description part of the cert to the real signature. This meant that a
      NULL algorithm parameters entry would look identical to an array of REAL
      (size zero) to the library and thus the certificate would be considered
      valid. However, if the parameters do not match in *any* way then the
      certificate should be considered invalid, and indeed OpenSSL marks these
      certs as invalid when mbedtls did not.
      Many thanks to guidovranken who found this issue via differential fuzzing
      and reported it in #3629.
    * Zeroising of local buffers and variables which are used for calculations
      in mbedtls_pkcs5_pbkdf2_hmac(), mbedtls_internal_sha*_process(),
      mbedtls_internal_md*_process() and mbedtls_internal_ripemd160_process()
      functions to erase sensitive data from memory. Reported by
      Johan Malmgren and Johan Uppman Bruce from Sectra.
 
 Bugfix
    * Fix an invalid (but nonzero) return code from mbedtls_pk_parse_subpubkey()
      when the input has trailing garbage. Fixes #2512.
    * Fix build failure in configurations where MBEDTLS_USE_PSA_CRYPTO is
      enabled but ECDSA is disabled. Contributed by jdurkop. Fixes #3294.
    * Include the psa_constant_names generated source code in the source tree
      instead of generating it at build time. Fixes #3524.
    * Fix rsa_prepare_blinding() to retry when the blinding value is not
      invertible (mod N), instead of returning MBEDTLS_ERR_RSA_RNG_FAILED. This
      addresses a regression but is rare in practice (approx. 1 in 2/sqrt(N)).
      Found by Synopsys Coverity, fix contributed by Peter Kolbus (Garmin).
      Fixes #3647.
    * Use socklen_t on Android and other POSIX-compliant system
    * Fix the build when the macro _GNU_SOURCE is defined to a non-empty value.
      Fix #3432.
    * Consistently return PSA_ERROR_INVALID_ARGUMENT on invalid cipher input
      sizes (instead of PSA_ERROR_BAD_STATE in some cases) to make the
      psa_cipher_* functions compliant with the PSA Crypto API specification.
    * mbedtls_ecp_curve_list() now lists Curve25519 and Curve448 under the names
      "x25519" and "x448". These curves support ECDH but not ECDSA. If you need
      only the curves that support ECDSA, filter the list with
      mbedtls_ecdsa_can_do().
    * Fix psa_generate_key() returning an error when asked to generate
      an ECC key pair on Curve25519 or secp244k1.
    * Fix psa_key_derivation_output_key() to allow the output of a combined key
      agreement and subsequent key derivation operation to be used as a key
      inside of the PSA Crypto core.
    * Fix handling of EOF against 0xff bytes and on platforms with unsigned
      chars. Fixes a build failure on platforms where char is unsigned. Fixes
      #3794.
    * Fix an off-by-one error in the additional data length check for
      CCM, which allowed encryption with a non-standard length field.
      Fixes #3719.
    * Correct the default IV size for mbedtls_cipher_info_t structures using
      MBEDTLS_MODE_ECB to 0, since ECB mode ciphers don't use IVs.
    * Make arc4random_buf available on NetBSD and OpenBSD when _POSIX_C_SOURCE is
      defined. Fix contributed in #3571.
    * Fix conditions for including string.h in error.c. Fixes #3866.
    * psa_set_key_id() now also sets the lifetime to persistent for keys located
      in a secure element.
    * Attempting to create a volatile key with a non-zero key identifier now
      fails. Previously the key identifier was just ignored when creating a
      volatile key.
    * Attempting to create or register a key with a key identifier in the vendor
      range now fails.
    * Fix build failures on GCC 11. Fixes #3782.
    * Add missing arguments of debug message in mbedtls_ssl_decrypt_buf.
    * Fix a memory leak in mbedtls_mpi_sub_abs() when the result was negative
      (an error condition) and the second operand was aliased to the result.
    * Fix a case in elliptic curve arithmetic where an out-of-memory condition
      could go undetected, resulting in an incorrect result.
    * In CTR_DRBG and HMAC_DRBG, don't reset the reseed interval in seed().
      Fixes #2927.
    * In PEM writing functions, fill the trailing part of the buffer with null
      bytes. This guarantees that the corresponding parsing function can read
      the buffer back, which was the case for mbedtls_x509write_{crt,csr}_pem
      until this property was inadvertently broken in Mbed TLS 2.19.0.
      Fixes #3682.
    * Fix a build failure that occurred with the MBEDTLS_AES_SETKEY_DEC_ALT
      option on. In this configuration key management methods that are required
      for MBEDTLS_CIPHER_MODE_XTS were excluded from the build and made it fail.
      Fixes #3818. Reported by John Stroebel.
 
 Changes
    * Reduce stack usage significantly during sliding window exponentiation.
      Reported in #3591 and fix contributed in #3592 by Daniel Otte.
    * The PSA persistent storage format is updated to always store the key bits
      attribute. No automatic upgrade path is provided. Previously stored keys
      must be erased, or manually upgraded based on the key storage format
      specification (docs/architecture/mbed-crypto-storage-specification.md).
      Fixes #3740.
    * Remove the zeroization of a pointer variable in AES rounds. It was valid
      but spurious and misleading since it looked like a mistaken attempt to
      zeroize the pointed-to buffer. Reported by Antonio de la Piedra, CEA
      Leti, France.
 
 = mbed TLS 2.24.0 branch released 2020-09-01
 
 API changes
    * In the PSA API, rename the types of elliptic curve and Diffie-Hellman
      group families to psa_ecc_family_t and psa_dh_family_t, in line with the
      PSA Crypto API specification version 1.0.0.
      Rename associated macros as well:
      PSA_ECC_CURVE_xxx renamed to PSA_ECC_FAMILY_xxx
      PSA_DH_GROUP_xxx renamed to PSA_DH_FAMILY_xxx
      PSA_KEY_TYPE_GET_CURVE renamed to to PSA_KEY_TYPE_ECC_GET_FAMILY
      PSA_KEY_TYPE_GET_GROUP renamed to PSA_KEY_TYPE_DH_GET_FAMILY
 
 Default behavior changes
    * Stop storing persistent information about externally stored keys created
      through PSA Crypto with a volatile lifetime. Reported in #3288 and
      contributed by Steven Cooreman in #3382.
 
 Features
    * The new function mbedtls_ecp_write_key() exports private ECC keys back to
      a byte buffer. It is the inverse of the existing mbedtls_ecp_read_key().
    * Support building on e2k (Elbrus) architecture: correctly enable
      -Wformat-signedness, and fix the code that causes signed-one-bit-field
      and sign-compare warnings. Contributed by makise-homura (Igor Molchanov)
      <akemi_homura@kurisa.ch>.
 
 Security
    * Fix a vulnerability in the verification of X.509 certificates when
      matching the expected common name (the cn argument of
      mbedtls_x509_crt_verify()) with the actual certificate name: when the
      subjecAltName extension is present, the expected name was compared to any
      name in that extension regardless of its type. This means that an
      attacker could for example impersonate a 4-bytes or 16-byte domain by
      getting a certificate for the corresponding IPv4 or IPv6 (this would
      require the attacker to control that IP address, though). Similar attacks
      using other subjectAltName name types might be possible. Found and
      reported by kFYatek in #3498.
    * When checking X.509 CRLs, a certificate was only considered as revoked if
      its revocationDate was in the past according to the local clock if
      available. In particular, on builds without MBEDTLS_HAVE_TIME_DATE,
      certificates were never considered as revoked. On builds with
      MBEDTLS_HAVE_TIME_DATE, an attacker able to control the local clock (for
      example, an untrusted OS attacking a secure enclave) could prevent
      revocation of certificates via CRLs. Fixed by no longer checking the
      revocationDate field, in accordance with RFC 5280. Reported by
      yuemonangong in #3340. Reported independently and fixed by
      Raoul Strackx and Jethro Beekman in #3433.
    * In (D)TLS record decryption, when using a CBC ciphersuites without the
      Encrypt-then-Mac extension, use constant code flow memory access patterns
      to extract and check the MAC. This is an improvement to the existing
      countermeasure against Lucky 13 attacks. The previous countermeasure was
      effective against network-based attackers, but less so against local
      attackers. The new countermeasure defends against local attackers, even
      if they have access to fine-grained measurements. In particular, this
      fixes a local Lucky 13 cache attack found and reported by Tuba Yavuz,
      Farhaan Fowze, Ken (Yihan) Bai, Grant Hernandez, and Kevin Butler
      (University of Florida) and Dave Tian (Purdue University).
    * Fix side channel in RSA private key operations and static (finite-field)
      Diffie-Hellman. An adversary with precise enough timing and memory access
      information (typically an untrusted operating system attacking a secure
      enclave) could bypass an existing counter-measure (base blinding) and
      potentially fully recover the private key.
    * Fix a 1-byte buffer overread in mbedtls_x509_crl_parse_der().
      Credit to OSS-Fuzz for detecting the problem and to Philippe Antoine
      for pinpointing the problematic code.
    * Zeroising of plaintext buffers in mbedtls_ssl_read() to erase unused
      application data from memory. Reported in #689 by
      Johan Uppman Bruce of Sectra.
 
 Bugfix
    * Library files installed after a CMake build no longer have execute
      permission.
    * Use local labels in mbedtls_padlock_has_support() to fix an invalid symbol
      redefinition if the function is inlined.
      Reported in #3451 and fix contributed in #3452 by okhowang.
    * Fix the endianness of Curve25519 keys imported/exported through the PSA
      APIs. psa_import_key and psa_export_key will now correctly expect/output
      Montgomery keys in little-endian as defined by RFC7748. Contributed by
      Steven Cooreman in #3425.
    * Fix build errors when the only enabled elliptic curves are Montgomery
      curves. Raised by signpainter in #941 and by Taiki-San in #1412. This
      also fixes missing declarations reported by Steven Cooreman in #1147.
    * Fix self-test failure when the only enabled short Weierstrass elliptic
      curve is secp192k1. Fixes #2017.
    * PSA key import will now correctly import a Curve25519/Curve448 public key
      instead of erroring out. Contributed by Steven Cooreman in #3492.
    * Use arc4random_buf on NetBSD instead of rand implementation with cyclical
      lower bits. Fix contributed in #3540.
    * Fix a memory leak in mbedtls_md_setup() when using HMAC under low memory
      conditions. Reported and fix suggested by Guido Vranken in #3486.
    * Fix bug in redirection of unit test outputs on platforms where stdout is
      defined as a macro. First reported in #2311 and fix contributed in #3528.
 
 Changes
    * Only pass -Wformat-signedness to versions of GCC that support it. Reported
      in #3478 and fix contributed in #3479 by okhowang.
    * Reduce the stack consumption of mbedtls_x509write_csr_der() which
      previously could lead to stack overflow on constrained devices.
      Contributed by Doru Gucea and Simon Leet in #3464.
    * Undefine the ASSERT macro before defining it locally, in case it is defined
      in a platform header. Contributed by Abdelatif Guettouche in #3557.
    * Update copyright notices to use Linux Foundation guidance. As a result,
      the copyright of contributors other than Arm is now acknowledged, and the
      years of publishing are no longer tracked in the source files. This also
      eliminates the need for the lines declaring the files to be part of
      MbedTLS. Fixes #3457.
    * Add the command line parameter key_pwd to the ssl_client2 and ssl_server2
      example applications which allows to provide a password for the key file
      specified through the existing key_file argument. This allows the use of
      these applications with password-protected key files. Analogously but for
      ssl_server2 only, add the command line parameter key_pwd2 which allows to
      set a password for the key file provided through the existing key_file2
      argument.
 
 = mbed TLS 2.23.0 branch released 2020-07-01
 
 Default behavior changes
    * In the experimental PSA secure element interface, change the encoding of
      key lifetimes to encode a persistence level and the location. Although C
      prototypes do not effectively change, code calling
      psa_register_se_driver() must be modified to pass the driver's location
      instead of the keys' lifetime. If the library is upgraded on an existing
      device, keys created with the old lifetime value will not be readable or
      removable through Mbed TLS after the upgrade.
 
 Features
    * New functions in the error module return constant strings for
      high- and low-level error codes, complementing mbedtls_strerror()
      which constructs a string for any error code, including compound
      ones, but requires a writable buffer. Contributed by Gaurav Aggarwal
      in #3176.
    * The new utility programs/ssl/ssl_context_info prints a human-readable
      dump of an SSL context saved with mbedtls_ssl_context_save().
    * Add support for midipix, a POSIX layer for Microsoft Windows.
    * Add new mbedtls_x509_crt_parse_der_with_ext_cb() routine which allows
      parsing unsupported certificate extensions via user provided callback.
      Contributed by Nicola Di Lieto <nicola.dilieto@gmail.com> in #3243 as
      a solution to #3241.
    * Pass the "certificate policies" extension to the callback supplied to
      mbedtls_x509_crt_parse_der_with_ext_cb() if it contains unsupported
      policies (#3419).
    * Added support to entropy_poll for the kern.arandom syscall supported on
      some BSD systems. Contributed by Nia Alarie in #3423.
    * Add support for Windows 2000 in net_sockets. Contributed by opatomic. #3239
 
 Security
    * Fix a side channel vulnerability in modular exponentiation that could
      reveal an RSA private key used in a secure enclave. Noticed by Sangho Lee,
      Ming-Wei Shih, Prasun Gera, Taesoo Kim and Hyesoon Kim (Georgia Institute
      of Technology); and Marcus Peinado (Microsoft Research). Reported by Raoul
      Strackx (Fortanix) in #3394.
    * Fix side channel in mbedtls_ecp_check_pub_priv() and
      mbedtls_pk_parse_key() / mbedtls_pk_parse_keyfile() (when loading a
      private key that didn't include the uncompressed public key), as well as
      mbedtls_ecp_mul() / mbedtls_ecp_mul_restartable() when called with a NULL
      f_rng argument. An attacker with access to precise enough timing and
      memory access information (typically an untrusted operating system
      attacking a secure enclave) could fully recover the ECC private key.
      Found and reported by Alejandro Cabrera Aldaya and Billy Brumley.
    * Fix issue in Lucky 13 counter-measure that could make it ineffective when
      hardware accelerators were used (using one of the MBEDTLS_SHAxxx_ALT
      macros). This would cause the original Lucky 13 attack to be possible in
      those configurations, allowing an active network attacker to recover
      plaintext after repeated timing measurements under some conditions.
      Reported and fix suggested by Luc Perneel in #3246.
 
 Bugfix
    * Fix the Visual Studio Release x64 build configuration for mbedtls itself.
      Completes a previous fix in Mbed TLS 2.19 that only fixed the build for
      the example programs. Reported in #1430 and fix contributed by irwir.
    * Fix undefined behavior in X.509 certificate parsing if the
      pathLenConstraint basic constraint value is equal to INT_MAX.
      The actual effect with almost every compiler is the intended
      behavior, so this is unlikely to be exploitable anywhere. #3192
    * Fix issue with a detected HW accelerated record error not being exposed
      due to shadowed variable. Contributed by Sander Visser in #3310.
    * Avoid NULL pointer dereferencing if mbedtls_ssl_free() is called with a
      NULL pointer argument. Contributed by Sander Visser in #3312.
    * Fix potential linker errors on dual world platforms by inlining
      mbedtls_gcc_group_to_psa(). This allows the pk.c module to link separately
      from psa_crypto.c. Fixes #3300.
    * Remove dead code in X.509 certificate parsing. Contributed by irwir in
      #2855.
    * Include asn1.h in error.c. Fixes #3328 reported by David Hu.
    * Fix potential memory leaks in ecp_randomize_jac() and ecp_randomize_mxz()
      when PRNG function fails. Contributed by Jonas Lejeune in #3318.
    * Remove unused macros from MSVC projects. Reported in #3297 and fix
      submitted in #3333 by irwir.
    * Add additional bounds checks in ssl_write_client_hello() preventing
      output buffer overflow if the configuration declared a buffer that was
      too small.
    * Set _POSIX_C_SOURCE to at least 200112L in C99 code. Reported in #3420 and
      fix submitted in #3421 by Nia Alarie.
    * Fix building library/net_sockets.c and the ssl_mail_client program on
      NetBSD. Contributed by Nia Alarie in #3422.
    * Fix false positive uninitialised variable reported by cpp-check.
      Contributed by Sander Visser in #3311.
    * Update iv and len context pointers manually when reallocating buffers
      using the MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH feature. This caused issues
      when receiving a connection with CID, when these fields were shifted
      in ssl_parse_record_header().
 
 Changes
    * Fix warnings about signedness issues in format strings. The build is now
      clean of -Wformat-signedness warnings. Contributed by Kenneth Soerensen
      in #3153.
    * Fix minor performance issue in operations on Curve25519 caused by using a
      suboptimal modular reduction in one place. Found and fix contributed by
      Aurelien Jarno in #3209.
    * Combine identical cases in switch statements in md.c. Contributed
      by irwir in #3208.
    * Simplify a bounds check in ssl_write_certificate_request(). Contributed
      by irwir in #3150.
    * Unify the example programs termination to call mbedtls_exit() instead of
      using a return command. This has been done to enable customization of the
      behavior in bare metal environments.
    * Fix mbedtls_x509_dn_gets to escape non-ASCII characters as "?".
      Contributed by Koh M. Nakagawa in #3326.
    * Use FindPython3 when cmake version >= 3.15.0
    * Abort the ClientHello writing function as soon as some extension doesn't
      fit into the record buffer. Previously, such extensions were silently
      dropped. As a consequence, the TLS handshake now fails when the output
      buffer is not large enough to hold the ClientHello.
    * The unit tests now rely on header files in framework/tests/include/test and source
      files in framework/tests/src. When building with make or cmake, the files in
      framework/tests/src are compiled and the resulting object linked into each test
      executable.
    * The ECP module, enabled by `MBEDTLS_ECP_C`, now depends on
      `MBEDTLS_CTR_DRBG_C` or `MBEDTLS_HMAC_DRBG_C` for some side-channel
      coutermeasures. If side channels are not a concern, this dependency can
      be avoided by enabling the new option `MBEDTLS_ECP_NO_INTERNAL_RNG`.
    * Align MSVC error flag with GCC and Clang. Contributed by Carlos Gomes
      Martinho. #3147
    * Remove superfluous assignment in mbedtls_ssl_parse_certificate(). Reported
      in #3182 and fix submitted by irwir. #3217
    * Fix typo in XTS tests. Reported and fix submitted by Kxuan. #3319
 
 = mbed TLS 2.22.0 branch released 2020-04-14
 
 New deprecations
    * Deprecate MBEDTLS_SSL_HW_RECORD_ACCEL that enables function hooks in the
      SSL module for hardware acceleration of individual records.
    * Deprecate mbedtls_ssl_get_max_frag_len() in favour of
      mbedtls_ssl_get_output_max_frag_len() and
      mbedtls_ssl_get_input_max_frag_len() to be more precise about which max
      fragment length is desired.
 
 Security
    * Fix issue in DTLS handling of new associations with the same parameters
      (RFC 6347 section 4.2.8): an attacker able to send forged UDP packets to
      the server could cause it to drop established associations with
      legitimate clients, resulting in a Denial of Service. This could only
      happen when MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE was enabled in config.h
      (which it is by default).
    * Fix side channel in ECC code that allowed an adversary with access to
      precise enough timing and memory access information (typically an
      untrusted operating system attacking a secure enclave) to fully recover
      an ECDSA private key. Found and reported by Alejandro Cabrera Aldaya,
      Billy Brumley and Cesar Pereida Garcia. CVE-2020-10932
    * Fix a potentially remotely exploitable buffer overread in a
      DTLS client when parsing the Hello Verify Request message.
 
 Features
    * The new build option MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH automatically
      resizes the I/O buffers before and after handshakes, reducing the memory
      consumption during application data transfer.
 
 Bugfix
    * Fix compilation failure when both MBEDTLS_SSL_PROTO_DTLS and
      MBEDTLS_SSL_HW_RECORD_ACCEL are enabled.
    * Remove a spurious check in ssl_parse_client_psk_identity that triggered
      a warning with some compilers. Fix contributed by irwir in #2856.
    * Fix a function name in a debug message. Contributed by Ercan Ozturk in
      #3013.
 
 Changes
    * Mbed Crypto is no longer a Git submodule. The crypto part of the library
      is back directly in the present repository.
    * Split mbedtls_ssl_get_max_frag_len() into
      mbedtls_ssl_get_output_max_frag_len() and
      mbedtls_ssl_get_input_max_frag_len() to ensure that a sufficient input
      buffer is allocated by the server (if MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH
      is defined), regardless of what MFL was configured for it.
 
 = mbed TLS 2.21.0 branch released 2020-02-20
 
 New deprecations
    * Deprecate MBEDTLS_SSL_SRV_SUPPORT_SSLV2_CLIENT_HELLO that enables parsing
      SSLv2 ClientHello messages.
    * Deprecate MBEDTLS_SSL_PROTO_SSL3 that enables support for SSLv3.
    * Deprecate for MBEDTLS_PKCS11_C, the wrapper around the pkcs11-helper
      library which allows TLS authentication to use keys stored in a
      PKCS#11 token such as a smartcard.
 
 Security
    * Fix potential memory overread when performing an ECDSA signature
      operation. The overread only happens with cryptographically low
      probability (of the order of 2^-n where n is the bitsize of the curve)
      unless the RNG is broken, and could result in information disclosure or
      denial of service (application crash or extra resource consumption).
      Found by Auke Zeilstra and Peter Schwabe, using static analysis.
    * To avoid a side channel vulnerability when parsing an RSA private key,
      read all the CRT parameters from the DER structure rather than
      reconstructing them. Found by Alejandro Cabrera Aldaya and Billy Bob
      Brumley. Reported and fix contributed by Jack Lloyd.
      ARMmbed/mbed-crypto#352
 
 Features
    * The new build option MBEDTLS_SHA512_NO_SHA384 allows building SHA-512
      support without SHA-384.
 
 API changes
    * Change the encoding of key types and curves in the PSA API. The new
      values are aligned with the upcoming release of the PSA Crypto API
      specification version 1.0.0. The main change which may break some
      existing code is that elliptic curve key types no longer encode the
      exact curve: a psa_ecc_curve_t or psa_key_type_t value only encodes
      a curve family and the key size determines the exact curve (for example,
      PSA_ECC_CURVE_SECP_R1 with 256 bits is P256R1). ARMmbed/mbed-crypto#330
 
 Bugfix
    * Fix an unchecked call to mbedtls_md() in the x509write module.
    * Fix build failure with MBEDTLS_ZLIB_SUPPORT enabled. Reported by
      Jack Lloyd in #2859. Fix submitted by jiblime in #2963.
    * Fix some false-positive uninitialized variable warnings in X.509. Fix
      contributed by apple-ihack-geek in #2663.
    * Fix a possible error code mangling in psa_mac_verify_finish() when
      a cryptographic accelerator fails. ARMmbed/mbed-crypto#345
    * Fix a bug in mbedtls_pk_parse_key() that would cause it to accept some
      RSA keys that would later be rejected by functions expecting private
      keys. Found by Catena cyber using oss-fuzz (issue 20467).
    * Fix a bug in mbedtls_pk_parse_key() that would cause it to
      accept some RSA keys with invalid values by silently fixing those values.
 
 = mbed TLS 2.20.0 branch released 2020-01-15
 
 Default behavior changes
    * The initial seeding of a CTR_DRBG instance makes a second call to the
      entropy function to obtain entropy for a nonce if the entropy size is less
      than 3/2 times the key size. In case you want to disable the extra call to
      grab entropy, you can call mbedtls_ctr_drbg_set_nonce_len() to force the
      nonce length to 0.
 
 Security
    * Enforce that mbedtls_entropy_func() gathers a total of
      MBEDTLS_ENTROPY_BLOCK_SIZE bytes or more from strong sources. In the
      default configuration, on a platform with a single entropy source, the
      entropy module formerly only grabbed 32 bytes, which is good enough for
      security if the source is genuinely strong, but less than the expected 64
      bytes (size of the entropy accumulator).
    * Zeroize local variables in mbedtls_internal_aes_encrypt() and
      mbedtls_internal_aes_decrypt() before exiting the function. The value of
      these variables can be used to recover the last round key. To follow best
      practice and to limit the impact of buffer overread vulnerabilities (like
      Heartbleed) we need to zeroize them before exiting the function.
      Issue reported by Tuba Yavuz, Farhaan Fowze, Ken (Yihang) Bai,
      Grant Hernandez, and Kevin Butler (University of Florida) and
      Dave Tian (Purdue University).
    * Fix side channel vulnerability in ECDSA. Our bignum implementation is not
      constant time/constant trace, so side channel attacks can retrieve the
      blinded value, factor it (as it is smaller than RSA keys and not guaranteed
      to have only large prime factors), and then, by brute force, recover the
      key. Reported by Alejandro Cabrera Aldaya and Billy Brumley.
    * Fix side channel vulnerability in ECDSA key generation. Obtaining precise
      timings on the comparison in the key generation enabled the attacker to
      learn leading bits of the ephemeral key used during ECDSA signatures and to
      recover the private key. Reported by Jeremy Dubeuf.
    * Catch failure of AES functions in mbedtls_ctr_drbg_random(). Uncaught
      failures could happen with alternative implementations of AES. Bug
      reported and fix proposed by Johan Uppman Bruce and Christoffer Lauri,
      Sectra.
 
 Features
    * Key derivation inputs in the PSA API can now either come from a key object
      or from a buffer regardless of the step type.
    * The CTR_DRBG module can grab a nonce from the entropy source during the
      initial seeding. The default nonce length is chosen based on the key size
      to achieve the security strength defined by NIST SP 800-90A. You can
      change it with mbedtls_ctr_drbg_set_nonce_len().
    * Add ENUMERATED tag support to the ASN.1 module. Contributed by
      msopiha-linaro in ARMmbed/mbed-crypto#307.
 
 API changes
    * In the PSA API, forbid zero-length keys. To pass a zero-length input to a
      key derivation function, use a buffer instead (this is now always
      possible).
    * Rename psa_asymmetric_sign() to psa_sign_hash() and
      psa_asymmetric_verify() to psa_verify_hash().
 
 Bugfix
    * Fix an incorrect size in a debugging message. Reported and fix
      submitted by irwir. Fixes #2717.
    * Fix an unused variable warning when compiling without DTLS.
      Reported and fix submitted by irwir. Fixes #2800.
    * Remove a useless assignment. Reported and fix submitted by irwir.
      Fixes #2801.
    * Fix a buffer overflow in the PSA HMAC code when using a long key with an
      unsupported algorithm. Fixes ARMmbed/mbed-crypto#254.
    * Fix mbedtls_asn1_get_int to support any number of leading zeros. Credit
      to OSS-Fuzz for finding a bug in an intermediate version of the fix.
    * Fix mbedtls_asn1_get_bitstring_null to correctly parse bitstrings of at
      most 2 bytes.
    * mbedtls_ctr_drbg_set_entropy_len() and
      mbedtls_hmac_drbg_set_entropy_len() now work if you call them before
      mbedtls_ctr_drbg_seed() or mbedtls_hmac_drbg_seed().
 
 Changes
    * Remove the technical possibility to define custom mbedtls_md_info
      structures, which was exposed only in an internal header.
    * psa_close_key(0) and psa_destroy_key(0) now succeed (doing nothing, as
      before).
    * Variables containing error codes are now initialized to an error code
      rather than success, so that coding mistakes or memory corruption tends to
      cause functions to return this error code rather than a success. There are
      no known instances where this changes the behavior of the library: this is
      merely a robustness improvement. ARMmbed/mbed-crypto#323
    * Remove a useless call to mbedtls_ecp_group_free(). Contributed by
      Alexander Krizhanovsky in ARMmbed/mbed-crypto#210.
    * Speed up PBKDF2 by caching the digest calculation. Contributed by Jack
      Lloyd and Fortanix Inc in ARMmbed/mbed-crypto#277.
    * Small performance improvement of mbedtls_mpi_div_mpi(). Contributed by
      Alexander Krizhanovsky in ARMmbed/mbed-crypto#308.
 
 = mbed TLS 2.19.1 branch released 2019-09-16
 
 Features
    * Declare include headers as PUBLIC to propagate to CMake project consumers
      Contributed by Zachary J. Fields in PR #2949.
    * Add nss_keylog to ssl_client2 and ssl_server2, enabling easier analysis of
      TLS sessions with tools like Wireshark.
 
 API Changes
    * Make client_random and server_random const in
      mbedtls_ssl_export_keys_ext_t, so that the key exporter is discouraged
      from modifying the client/server hello.
 
 Bugfix
    * Fix some false-positive uninitialized variable warnings in crypto. Fix
      contributed by apple-ihack-geek in #2663.
 
 = mbed TLS 2.19.0 branch released 2019-09-06
 
 Security
    * Fix a missing error detection in ECJPAKE. This could have caused a
      predictable shared secret if a hardware accelerator failed and the other
      side of the key exchange had a similar bug.
    * When writing a private EC key, use a constant size for the private
      value, as specified in RFC 5915. Previously, the value was written
      as an ASN.1 INTEGER, which caused the size of the key to leak
      about 1 bit of information on average and could cause the value to be
      1 byte too large for the output buffer.
    * The deterministic ECDSA calculation reused the scheme's HMAC-DRBG to
      implement blinding. Because of this for the same key and message the same
      blinding value was generated. This reduced the effectiveness of the
      countermeasure and leaked information about the private key through side
      channels. Reported by Jack Lloyd.
 
 Features
    * Add new API functions mbedtls_ssl_session_save() and
      mbedtls_ssl_session_load() to allow serializing a session, for example to
      store it in non-volatile storage, and later using it for TLS session
      resumption.
    * Add a new API function mbedtls_ssl_check_record() to allow checking that
      an incoming record is valid, authentic and has not been seen before. This
      feature can be used alongside Connection ID and SSL context serialisation.
      The feature is enabled at compile-time by MBEDTLS_SSL_RECORD_CHECKING
      option.
    * New implementation of X25519 (ECDH using Curve25519) from Project Everest
      (https://project-everest.github.io/). It can be enabled at compile time
      with MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED. This implementation is formally
      verified and significantly faster, but is only supported on x86 platforms
      (32-bit and 64-bit) using GCC, Clang or Visual Studio. Contributed by
      Christoph Wintersteiger from Microsoft Research.
    * Add mbedtls_net_close(), enabling the building of forking servers where
      the parent process closes the client socket and continue accepting, and
      the child process closes the listening socket and handles the client
      socket. Contributed by Robert Larsen in #2803.
 
 API Changes
    * Add DER-encoded test CRTs to library/certs.c, allowing
      the example programs ssl_server2 and ssl_client2 to be run
      if MBEDTLS_FS_IO and MBEDTLS_PEM_PARSE_C are unset. Fixes #2254.
    * The HAVEGE state type now uses uint32_t elements instead of int.
    * The functions mbedtls_ecp_curve_list() and mbedtls_ecp_grp_id_list() now
      list all curves for which at least one of ECDH or ECDSA is supported, not
      just curves for which both are supported. Call mbedtls_ecdsa_can_do() or
      mbedtls_ecdh_can_do() on each result to check whether each algorithm is
      supported.
    * The new function mbedtls_ecdsa_sign_det_ext() is similar to
      mbedtls_ecdsa_sign_det() but allows passing an external RNG for the
      purpose of blinding.
 
 New deprecations
    * Deprecate mbedtls_ecdsa_sign_det() in favor of a functions that can take an
      RNG function as an input.
    * Calling mbedtls_ecdsa_write_signature() with NULL as the f_rng argument
      is now deprecated.
 
 Bugfix
    * Fix missing bounds checks in X.509 parsing functions that could
      lead to successful parsing of ill-formed X.509 CRTs. Fixes #2437.
    * Fix multiple X.509 functions previously returning ASN.1 low-level error
      codes to always wrap these codes into X.509 high level error codes before
      returning. Fixes #2431.
    * Fix to allow building test suites with any warning that detects unused
      functions. Fixes #1628.
    * Fix typo in net_would_block(). Fixes #528 reported by github-monoculture.
    * Remove redundant include file in timing.c. Fixes #2640 reported by irwir.
    * Fix build failure when building with mingw on Windows by including
      stdarg.h where needed. Fixes #2656.
    * Fix Visual Studio Release x64 build configuration by inheriting
      PlatformToolset from the project configuration. Fixes #1430 reported by
      irwir.
    * Enable Suite B with subset of ECP curves. Make sure the code compiles even
      if some curves are not defined. Fixes #1591 reported by dbedev.
    * Fix misuse of signed arithmetic in the HAVEGE module. #2598
    * Avoid use of statically sized stack buffers for certificate writing.
      This previously limited the maximum size of DER encoded certificates
      in mbedtls_x509write_crt_der() to 2Kb. Reported by soccerGB in #2631.
    * Fix partial zeroing in x509_get_other_name. Found and fixed by ekse, #2716.
    * Update test certificates that were about to expire. Reported by
      Bernhard M. Wiedemann in #2357.
    * Fix the build on ARMv5TE in ARM mode to not use assembly instructions
      that are only available in Thumb mode. Fix contributed by Aurelien Jarno
      in #2169.
    * Fix propagation of restart contexts in restartable EC operations.
      This could previously lead to segmentation faults in builds using an
      address-sanitizer and enabling but not using MBEDTLS_ECP_RESTARTABLE.
    * Fix memory leak in in mpi_miller_rabin(). Contributed by
      Jens Wiklander <jens.wiklander@linaro.org> in #2363
    * Improve code clarity in x509_crt module, removing false-positive
      uninitialized variable warnings on some recent toolchains (GCC8, etc).
      Discovered and fixed by Andy Gross (Linaro), #2392.
    * Fix bug in endianness conversion in bignum module. This lead to
      functionally incorrect code on bigendian systems which don't have
      __BYTE_ORDER__ defined. Reported by Brendan Shanks. Fixes #2622.
 
 Changes
    * Replace multiple uses of MD2 by SHA-256 in X.509 test suite. Fixes #821.
    * Make it easier to define MBEDTLS_PARAM_FAILED as assert (which config.h
      suggests). #2671
    * Make `make clean` clean all programs always. Fixes #1862.
    * Add a Dockerfile and helper scripts (all-in-docker.sh, basic-in-docker.sh,
      docker-env.sh) to simplify running test suites on a Linux host. Contributed
      by Peter Kolbus (Garmin).
    * Add `reproducible` option to `ssl_client2` and `ssl_server2` to enable
      test runs without variability. Contributed by Philippe Antoine (Catena
      cyber) in #2681.
    * Extended .gitignore to ignore Visual Studio artifacts. Fixed by ConfusedSushi.
    * Adds fuzz targets, especially for continuous fuzzing with OSS-Fuzz.
      Contributed by Philippe Antoine (Catena cyber).
    * Remove the crypto part of the library from Mbed TLS. The crypto
      code and tests are now only available via Mbed Crypto, which
      Mbed TLS references as a Git submodule.
 
 = mbed TLS 2.18.1 branch released 2019-07-12
 
 Bugfix
    * Fix build failure when building with mingw on Windows by including
      stdarg.h where needed. Fixes #2656.
 
 Changes
    * Enable building of Mbed TLS as a CMake subproject. Suggested and fixed by
      Ashley Duncan in #2609.
 
 = mbed TLS 2.18.0 branch released 2019-06-11
 
 Features
    * Add the Any Policy certificate policy oid, as defined in
      rfc 5280 section 4.2.1.4.
    * It is now possible to use NIST key wrap mode via the mbedtls_cipher API.
      Contributed by Jack Lloyd and Fortanix Inc.
    * Add the Wi-SUN Field Area Network (FAN) device extended key usage.
    * Add the oid certificate policy x509 extension.
    * It is now possible to perform RSA PKCS v1.5 signatures with RIPEMD-160 digest.
      Contributed by Jack Lloyd and Fortanix Inc.
    * Extend the MBEDTLS_SSL_EXPORT_KEYS to export the handshake randbytes,
      and the used tls-prf.
    * Add public API for tls-prf function, according to requested enum.
    * Add support for parsing otherName entries in the Subject Alternative Name
      X.509 certificate extension, specifically type hardware module name,
      as defined in RFC 4108 section 5.
    * Add support for parsing certificate policies extension, as defined in
      RFC 5280 section 4.2.1.4. Currently, only the "Any Policy" policy is
      supported.
    * List all SAN types in the subject_alt_names field of the certificate.
      Resolves #459.
    * Add support for draft-05 of the Connection ID extension, as specified
      in https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-05.
      The Connection ID extension allows to keep DTLS connections beyond the
      lifetime of the underlying transport by adding a connection identifier
      to the DTLS record header. This identifier can be used to associated an
      incoming record with the correct connection data even after the peer has
      changed its IP or port. The feature is enabled at compile-time by setting
      MBEDTLS_SSL_DTLS_CONNECTION_ID (disabled by default), and at run-time
      through the new APIs mbedtls_ssl_conf_cid() and mbedtls_ssl_set_cid().
 
 
 API Changes
    * Extend the MBEDTLS_SSL_EXPORT_KEYS to export the handshake randbytes,
      and the used tls-prf.
    * Add public API for tls-prf function, according to requested enum.
 
 Bugfix
    * Fix private key DER output in the key_app_writer example. File contents
      were shifted by one byte, creating an invalid ASN.1 tag. Fixed by
      Christian Walther in #2239.
    * Fix potential memory leak in X.509 self test. Found and fixed by
      Junhwan Park, #2106.
    * Reduce stack usage of hkdf tests. Fixes #2195.
    * Fix 1-byte buffer overflow in mbedtls_mpi_write_string() when
      used with negative inputs. Found by Guido Vranken in #2404. Credit to
      OSS-Fuzz.
    * Fix bugs in the AEAD test suite which would be exposed by ciphers which
      either used both encrypt and decrypt key schedules, or which perform padding.
      GCM and CCM were not affected. Fixed by Jack Lloyd.
    * Fix incorrect default port number in ssl_mail_client example's usage.
      Found and fixed by irwir. #2337
    * Add psa_util.h to test/cpp_dummy_build to fix build_default_make_gcc_and_cxx.
      Fixed by Peter Kolbus (Garmin). #2579
    * Add missing parentheses around parameters in the definition of the
      public macro MBEDTLS_X509_ID_FLAG. This could lead to invalid evaluation
      in case operators binding less strongly than subtraction were used
      for the parameter.
    * Add a check for MBEDTLS_X509_CRL_PARSE_C in ssl_server2, guarding the crl
      sni entry parameter. Reported by inestlerode in #560.
    * Set the next sequence of the subject_alt_name to NULL when deleting
      sequence on failure. Found and fix suggested by Philippe Antoine.
      Credit to OSS-Fuzz.
 
 Changes
    * Server's RSA certificate in certs.c was SHA-1 signed. In the default
      mbedTLS configuration only SHA-2 signed certificates are accepted.
      This certificate is used in the demo server programs, which lead the
      client programs to fail at the peer's certificate verification
      due to an unacceptable hash signature. The certificate has been
      updated to one that is SHA-256 signed. Fix contributed by
      Illya Gerasymchuk.
    * Return from various debugging routines immediately if the
      provided SSL context is unset.
    * Remove dead code from bignum.c in the default configuration.
      Found by Coverity, reported and fixed by Peter Kolbus (Garmin). Fixes #2309.
    * Add test for minimal value of MBEDTLS_MPI_WINDOW_SIZE to all.sh.
      Contributed by Peter Kolbus (Garmin).
    * Change wording in the `mbedtls_ssl_conf_max_frag_len()`'s documentation to
      improve clarity. Fixes #2258.
 
 = mbed TLS 2.17.0 branch released 2019-03-19
 
 Features
    * Add a new X.509 API call `mbedtls_x509_parse_der_nocopy()`
      which allows copy-less parsing of DER encoded X.509 CRTs,
      at the cost of additional lifetime constraints on the input
      buffer, but at the benefit of reduced RAM consumption.
    * Add a new function mbedtls_asn1_write_named_bitstring() to write ASN.1
      named bitstring in DER as required by RFC 5280 Appendix B.
    * Add MBEDTLS_REMOVE_3DES_CIPHERSUITES to allow removing 3DES ciphersuites
      from the default list (enabled by default). See
      https://sweet32.info/SWEET32_CCS16.pdf.
 
 API Changes
    * Add a new X.509 API call `mbedtls_x509_parse_der_nocopy()`.
      See the Features section for more information.
    * Allow to opt in to the removal the API mbedtls_ssl_get_peer_cert()
      for the benefit of saving RAM, by disabling the new compile-time
      option MBEDTLS_SSL_KEEP_PEER_CERTIFICATE (enabled by default for
      API stability). Disabling this option makes mbedtls_ssl_get_peer_cert()
      always return NULL, and removes the peer_cert field from the
      mbedtls_ssl_session structure which otherwise stores the peer's
      certificate.
 
 Security
    * Make mbedtls_ecdh_get_params return an error if the second key
      belongs to a different group from the first. Before, if an application
      passed keys that belonged to different group, the first key's data was
      interpreted according to the second group, which could lead to either
      an error or a meaningless output from mbedtls_ecdh_get_params. In the
      latter case, this could expose at most 5 bits of the private key.
 
 Bugfix
    * Fix a compilation issue with mbedtls_ecp_restart_ctx not being defined
      when MBEDTLS_ECP_ALT is defined. Reported by jwhui. Fixes #2242.
    * Run the AD too long test only if MBEDTLS_CCM_ALT is not defined.
      Raised as a comment in #1996.
    * Reduce the stack consumption of mbedtls_mpi_fill_random() which could
      previously lead to a stack overflow on constrained targets.
    * Add `MBEDTLS_SELF_TEST` for the mbedtls_self_test functions
      in the header files, which missed the precompilation check. #971
    * Fix returning the value 1 when mbedtls_ecdsa_genkey failed.
    * Remove a duplicate #include in a sample program. Fixed by Masashi Honma #2326.
    * Remove the mbedtls namespacing from the header file, to fix a "file not found"
      build error. Fixed by Haijun Gu #2319.
    * Fix signed-to-unsigned integer conversion warning
      in X.509 module. Fixes #2212.
    * Reduce stack usage of `mpi_write_hlp()` by eliminating recursion.
      Fixes #2190.
    * Fix false failure in all.sh when backup files exist in include/mbedtls
      (e.g. config.h.bak). Fixed by Peter Kolbus (Garmin) #2407.
    * Ensure that unused bits are zero when writing ASN.1 bitstrings when using
      mbedtls_asn1_write_bitstring().
    * Fix issue when writing the named bitstrings in KeyUsage and NsCertType
      extensions in CSRs and CRTs that caused these bitstrings to not be encoded
      correctly as trailing zeroes were not accounted for as unused bits in the
      leading content octet. Fixes #1610.
 
 Changes
    * Reduce RAM consumption during session renegotiation by not storing
      the peer CRT chain and session ticket twice.
    * Include configuration file in all header files that use configuration,
      instead of relying on other header files that they include.
      Inserted as an enhancement for #1371
    * Add support for alternative CSR headers, as used by Microsoft and defined
      in RFC 7468. Found by Michael Ernst. Fixes #767.
    * Correct many misspellings. Fixed by MisterDA #2371.
    * Provide an abstraction of vsnprintf to allow alternative implementations
      for platforms that don't provide it. Based on contributions by Joris Aerts
      and Nathaniel Wesley Filardo.
    * Fix clobber list in MIPS assembly for large integer multiplication.
      Previously, this could lead to functionally incorrect assembly being
      produced by some optimizing compilers, showing up as failures in
      e.g. RSA or ECC signature operations. Reported in #1722, fix suggested
      by Aurelien Jarno and submitted by Jeffrey Martin.
    * Reduce the complexity of the timing tests. They were assuming more than the
      underlying OS actually guarantees.
    * Fix configuration queries in ssl-opt.h. #2030
    * Ensure that ssl-opt.h can be run in OS X. #2029
    * Re-enable certain interoperability tests in ssl-opt.sh which had previously
      been disabled for lack of a sufficiently recent version of GnuTLS on the CI.
    * Ciphersuites based on 3DES now have the lowest priority by default when
      they are enabled.
 
 = mbed TLS 2.16.0 branch released 2018-12-21
 
 Features
    * Add a new config.h option of MBEDTLS_CHECK_PARAMS that enables validation
      of parameters in the API. This allows detection of obvious misuses of the
      API, such as passing NULL pointers. The API of existing functions hasn't
      changed, but requirements on parameters have been made more explicit in
      the documentation. See the corresponding API documentation for each
      function to see for which parameter values it is defined. This feature is
      disabled by default. See its API documentation in config.h for additional
      steps you have to take when enabling it.
 
 API Changes
    * The following functions in the random generator modules have been
      deprecated and replaced as shown below. The new functions change
      the return type from void to int to allow returning error codes when
      using MBEDTLS_<MODULE>_ALT for the underlying AES or message digest
      primitive. Fixes #1798.
      mbedtls_ctr_drbg_update() -> mbedtls_ctr_drbg_update_ret()
      mbedtls_hmac_drbg_update() -> mbedtls_hmac_drbg_update_ret()
    * Extend ECDH interface to enable alternative implementations.
    * Deprecate error codes of the form MBEDTLS_ERR_xxx_INVALID_KEY_LENGTH for
      ARIA, CAMELLIA and Blowfish. These error codes will be replaced by
      the more generic per-module error codes MBEDTLS_ERR_xxx_BAD_INPUT_DATA.
    * Additional parameter validation checks have been added for the following
      modules - AES, ARIA, Blowfish, CAMELLIA, CCM, GCM, DHM, ECP, ECDSA, ECDH,
      ECJPAKE, SHA, Chacha20 and Poly1305, cipher, pk, RSA, and MPI.
      Where modules have had parameter validation added, existing parameter
      checks may have changed. Some modules, such as Chacha20 had existing
      parameter validation whereas other modules had little. This has now been
      changed so that the same level of validation is present in all modules, and
      that it is now optional with the MBEDTLS_CHECK_PARAMS flag which by default
      is off. That means that checks which were previously present by default
      will no longer be.
 
 New deprecations
    * Deprecate mbedtls_ctr_drbg_update and mbedtls_hmac_drbg_update
      in favor of functions that can return an error code.
 
 Bugfix
    * Fix for Clang, which was reporting a warning for the bignum.c inline
      assembly for AMD64 targets creating string literals greater than those
      permitted by the ISO C99 standard. Found by Aaron Jones. Fixes #482.
    * Fix runtime error in `mbedtls_platform_entropy_poll()` when run
      through qemu user emulation. Reported and fix suggested by randombit
      in #1212. Fixes #1212.
    * Fix an unsafe bounds check when restoring an SSL session from a ticket.
      This could lead to a buffer overflow, but only in case ticket authentication
      was broken. Reported and fix suggested by Guido Vranken in #659.
    * Add explicit integer to enumeration type casts to example program
      programs/pkey/gen_key which previously led to compilation failure
      on some toolchains. Reported by phoenixmcallister. Fixes #2170.
    * Fix double initialization of ECC hardware that made some accelerators
      hang.
    * Clarify documentation of mbedtls_ssl_set_own_cert() regarding the absence
      of check for certificate/key matching. Reported by Attila Molnar, #507.
 
  = mbed TLS 2.15.1 branch released 2018-11-30
 
  Changes
     * Update the Mbed Crypto submodule to version 0.1.0b2.
 
  = mbed TLS 2.15.0 branch released 2018-11-23
 
  Features
     * Add an experimental build option, USE_CRYPTO_SUBMODULE, to enable use of
       Mbed Crypto as the source of the cryptography implementation.
     * Add an experimental configuration option, MBEDTLS_PSA_CRYPTO_C, to enable
       the PSA Crypto API from Mbed Crypto when additionally used with the
       USE_CRYPTO_SUBMODULE build option.
 
  Changes
     * Add unit tests for AES-GCM when called through mbedtls_cipher_auth_xxx()
       from the cipher abstraction layer. Fixes #2198.
 
 = mbed TLS 2.14.1 branch released 2018-11-30
 
 Security
    * Fix timing variations and memory access variations in RSA PKCS#1 v1.5
      decryption that could lead to a Bleichenbacher-style padding oracle
      attack. In TLS, this affects servers that accept ciphersuites based on
      RSA decryption (i.e. ciphersuites whose name contains RSA but not
      (EC)DH(E)). Discovered by Eyal Ronen (Weizmann Institute),  Robert Gillham
      (University of Adelaide), Daniel Genkin (University of Michigan),
      Adi Shamir (Weizmann Institute), David Wong (NCC Group), and Yuval Yarom
      (University of Adelaide, Data61). The attack is described in more detail
      in the paper available here: http://cat.eyalro.net/cat.pdf  CVE-2018-19608
    * In mbedtls_mpi_write_binary(), don't leak the exact size of the number
      via branching and memory access patterns. An attacker who could submit
      a plaintext for RSA PKCS#1 v1.5 decryption but only observe the timing
      of the decryption and not its result could nonetheless decrypt RSA
      plaintexts and forge RSA signatures. Other asymmetric algorithms may
      have been similarly vulnerable. Reported by Eyal Ronen, Robert Gillham,
      Daniel Genkin, Adi Shamir, David Wong and Yuval Yarom.
    * Wipe sensitive buffers on the stack in the CTR_DRBG and HMAC_DRBG
      modules.
 
 API Changes
    * The new functions mbedtls_ctr_drbg_update_ret() and
      mbedtls_hmac_drbg_update_ret() are similar to mbedtls_ctr_drbg_update()
      and mbedtls_hmac_drbg_update() respectively, but the new functions
      report errors whereas the old functions return void. We recommend that
      applications use the new functions.
 
 = mbed TLS 2.14.0 branch released 2018-11-19
 
 Security
    * Fix overly strict DN comparison when looking for CRLs belonging to a
      particular CA. This previously led to ignoring CRLs when the CRL's issuer
      name and the CA's subject name differed in their string encoding (e.g.,
      one using PrintableString and the other UTF8String) or in the choice of
      upper and lower case. Reported by Henrik Andersson of Bosch GmbH in issue
      #1784.
    * Fix a flawed bounds check in server PSK hint parsing. In case the
      incoming message buffer was placed within the first 64KiB of address
      space and a PSK-(EC)DHE ciphersuite was used, this allowed an attacker
      to trigger a memory access up to 64KiB beyond the incoming message buffer,
      potentially leading to an application crash or information disclosure.
    * Fix mbedtls_mpi_is_prime() to use more rounds of probabilistic testing. The
      previous settings for the number of rounds made it practical for an
      adversary to construct non-primes that would be erroneously accepted as
      primes with high probability. This does not have an impact on the
      security of TLS, but can matter in other contexts with numbers chosen
      potentially by an adversary that should be prime and can be validated.
      For example, the number of rounds was enough to securely generate RSA key
      pairs or Diffie-Hellman parameters, but was insufficient to validate
      Diffie-Hellman parameters properly.
      See "Prime and Prejudice" by by Martin R. Albrecht and Jake Massimo and
      Kenneth G. Paterson and Juraj Somorovsky.
 
 Features
    * Add support for temporarily suspending expensive ECC computations after
      some configurable amount of operations. This is intended to be used in
      constrained, single-threaded systems where ECC is time consuming and can
      block other operations until they complete. This is disabled by default,
      but can be enabled by MBEDTLS_ECP_RESTARTABLE at compile time and
      configured by mbedtls_ecp_set_max_ops() at runtime. It applies to the new
      xxx_restartable functions in ECP, ECDSA, PK and X.509 (CRL not supported
      yet), and to existing functions in ECDH and SSL (currently only
      implemented client-side, for ECDHE-ECDSA ciphersuites in TLS 1.2,
      including client authentication).
    * Add support for Arm CPU DSP extensions to accelerate asymmetric key
      operations. On CPUs where the extensions are available, they can accelerate
      MPI multiplications used in ECC and RSA cryptography. Contributed by
      Aurelien Jarno.
    * Extend RSASSA-PSS signature to allow a smaller salt size. Previously, PSS
      signature always used a salt with the same length as the hash, and returned
      an error if this was not possible. Now the salt size may be up to two bytes
      shorter. This allows the library to support all hash and signature sizes
      that comply with FIPS 186-4, including SHA-512 with a 1024-bit key.
    * Add support for 128-bit keys in CTR_DRBG. Note that using keys shorter
      than 256 bits limits the security of generated material to 128 bits.
 
 API Changes
    * Add a common error code of `MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED` for
      a feature that is not supported by underlying alternative
      implementations implementing cryptographic primitives. This is useful for
      hardware accelerators that don't implement all options or features.
 
 New deprecations
    * All module specific errors following the form
      MBEDTLS_ERR_XXX_FEATURE_UNAVAILABLE that indicate a feature is not
      supported are deprecated and are now replaced by the new equivalent
      platform error.
    * All module specific generic hardware acceleration errors following the
      form MBEDTLS_ERR_XXX_HW_ACCEL_FAILED that are deprecated and are replaced
      by the equivalent plaform error.
    * Deprecate the function mbedtls_mpi_is_prime() in favor of
      mbedtls_mpi_is_prime_ext() which allows specifying the number of
      Miller-Rabin rounds.
 
 Bugfix
    * Fix wrong order of freeing in programs/ssl/ssl_server2 example
      application leading to a memory leak in case both
      MBEDTLS_MEMORY_BUFFER_ALLOC_C and MBEDTLS_MEMORY_BACKTRACE are set.
      Fixes #2069.
    * Fix a bug in the update function for SSL ticket keys which previously
      invalidated keys of a lifetime of less than a 1s. Fixes #1968.
    * Fix failure in hmac_drbg in the benchmark sample application, when
      MBEDTLS_THREADING_C is defined. Found by TrinityTonic, #1095
    * Fix a bug in the record decryption routine ssl_decrypt_buf()
      which lead to accepting properly authenticated but improperly
      padded records in case of CBC ciphersuites using Encrypt-then-MAC.
    * Fix memory leak and freeing without initialization in the example
      program programs/x509/cert_write. Fixes #1422.
    * Ignore IV in mbedtls_cipher_set_iv() when the cipher mode is
      MBEDTLS_MODE_ECB. Found by ezdevelop. Fixes #1091.
    * Zeroize memory used for buffering or reassembling handshake messages
      after use.
    * Use `mbedtls_platform_zeroize()` instead of `memset()` for zeroization
      of sensitive data in the example programs aescrypt2 and crypt_and_hash.
    * Change the default string format used for various X.509 DN attributes to
      UTF8String. Previously, the use of the PrintableString format led to
      wildcards and non-ASCII characters being unusable in some DN attributes.
      Reported by raprepo in #1860 and by kevinpt in #468. Fix contributed by
      Thomas-Dee.
    * Fix compilation failure for configurations which use compile time
      replacements of standard calloc/free functions through the macros
      MBEDTLS_PLATFORM_CALLOC_MACRO and MBEDTLS_PLATFORM_FREE_MACRO.
      Reported by ole-de and ddhome2006. Fixes #882, #1642 and #1706.
 
 Changes
    * Removed support for Yotta as a build tool.
    * Add tests for session resumption in DTLS.
    * Close a test gap in (D)TLS between the client side and the server side:
      test the handling of large packets and small packets on the client side
      in the same way as on the server side.
    * Change the dtls_client and dtls_server samples to work by default over
      IPv6 and optionally by a build option over IPv4.
    * Change the use of Windows threading to use Microsoft Visual C++ runtime
      calls, rather than Win32 API calls directly. This is necessary to avoid
      conflict with C runtime usage. Found and fixed by irwir.
    * Remember the string format of X.509 DN attributes when replicating
      X.509 DNs. Previously, DN attributes were always written in their default
      string format (mostly PrintableString), which could lead to CRTs being
      created which used PrintableStrings in the issuer field even though the
      signing CA used UTF8Strings in its subject field; while X.509 compliant,
      such CRTs were rejected in some applications, e.g. some versions of
      Firefox, curl and GnuTLS. Reported in #1033 by Moschn. Fix contributed by
      Thomas-Dee.
    * Improve documentation of mbedtls_ssl_get_verify_result().
      Fixes #517 reported by github-monoculture.
    * Add MBEDTLS_MPI_GEN_PRIME_FLAG_LOW_ERR flag to mbedtls_mpi_gen_prime() and
      use it to reduce error probability in RSA key generation to levels mandated
      by FIPS-186-4.
 
 = mbed TLS 2.13.1 branch released 2018-09-06
 
 API Changes
    * Extend the platform module with an abstraction mbedtls_platform_gmtime_r()
      whose implementation should behave as a thread-safe version of gmtime().
      This allows users to configure such an implementation at compile time when
      the target system cannot be deduced automatically, by setting the option
      MBEDTLS_PLATFORM_GMTIME_R_ALT. At this stage Mbed TLS is only able to
      automatically select implementations for Windows and POSIX C libraries.
 
 Bugfix
    * Fix build failures on platforms where only gmtime() is available but
      neither gmtime_r() nor gmtime_s() are present. Fixes #1907.
 
 = mbed TLS 2.13.0 branch released 2018-08-31
 
 Security
    * Fix an issue in the X.509 module which could lead to a buffer overread
      during certificate extensions parsing. In case of receiving malformed
      input (extensions length field equal to 0), an illegal read of one byte
      beyond the input buffer is made. Found and analyzed by Nathan Crandall.
 
 Features
    * Add support for fragmentation of outgoing DTLS handshake messages. This
      is controlled by the maximum fragment length as set locally or negotiated
      with the peer, as well as by a new per-connection MTU option, set using
      mbedtls_ssl_set_mtu().
    * Add support for auto-adjustment of MTU to a safe value during the
      handshake when flights do not get through (RFC 6347, section 4.1.1.1,
      last paragraph).
    * Add support for packing multiple records within a single datagram,
      enabled by default.
    * Add support for buffering out-of-order handshake messages in DTLS.
      The maximum amount of RAM used for this can be controlled by the
      compile-time constant MBEDTLS_SSL_DTLS_MAX_BUFFERING defined
      in mbedtls/config.h.
 
 API Changes
    * Add function mbedtls_ssl_set_datagram_packing() to configure
      the use of datagram packing (enabled by default).
 
 Bugfix
    * Fix a potential memory leak in mbedtls_ssl_setup() function. An allocation
      failure in the function could lead to other buffers being leaked.
    * Fixes an issue with MBEDTLS_CHACHAPOLY_C which would not compile if
      MBEDTLS_ARC4_C and MBEDTLS_CIPHER_NULL_CIPHER weren't also defined. #1890
    * Fix a memory leak in ecp_mul_comb() if ecp_precompute_comb() fails.
      Fix contributed by Espressif Systems.
    * Add ecc extensions only if an ecc based ciphersuite is used.
      This improves compliance to RFC 4492, and as a result, solves
      interoperability issues with BouncyCastle. Raised by milenamil in #1157.
    * Replace printf with mbedtls_printf in the ARIA module. Found by
      TrinityTonic in #1908.
    * Fix potential use-after-free in mbedtls_ssl_get_max_frag_len()
      and mbedtls_ssl_get_record_expansion() after a session reset. Fixes #1941.
    * Fix a bug that caused SSL/TLS clients to incorrectly abort the handshake
      with TLS versions 1.1 and earlier when the server requested authentication
      without providing a list of CAs. This was due to an overly strict bounds
      check in parsing the CertificateRequest message,
      introduced in Mbed TLS 2.12.0. Fixes #1954.
    * Fix a miscalculation of the maximum record expansion in
      mbedtls_ssl_get_record_expansion() in case of ChachaPoly ciphersuites,
      or CBC ciphersuites in (D)TLS versions 1.1 or higher. Fixes #1913, #1914.
    * Fix undefined shifts with negative values in certificates parsing
      (found by Catena cyber using oss-fuzz)
    * Fix memory leak and free without initialization in pk_encrypt
      and pk_decrypt example programs. Reported by Brace Stout. Fixes #1128.
    * Remove redundant else statement. Raised by irwir. Fixes #1776.
 
 Changes
    * Copy headers preserving timestamps when doing a "make install".
      Contributed by xueruini.
    * Allow the forward declaration of public structs. Contributed by Dawid
      Drozd. Fixes #1215 raised by randombit.
    * Improve compatibility with some alternative CCM implementations by using
      CCM test vectors from RAM.
    * Add support for buffering of out-of-order handshake messages.
    * Add warnings to the documentation of the HKDF module to reduce the risk
      of misusing the mbedtls_hkdf_extract() and mbedtls_hkdf_expand()
      functions. Fixes #1775. Reported by Brian J. Murray.
 
 = mbed TLS 2.12.0 branch released 2018-07-25
 
 Security
    * Fix a vulnerability in TLS ciphersuites based on CBC and using SHA-384,
      in (D)TLS 1.0 to 1.2, that allowed an active network attacker to
      partially recover the plaintext of messages under some conditions by
      exploiting timing measurements. With DTLS, the attacker could perform
      this recovery by sending many messages in the same connection. With TLS
      or if mbedtls_ssl_conf_dtls_badmac_limit() was used, the attack only
      worked if the same secret (for example a HTTP Cookie) has been repeatedly
      sent over connections manipulated by the attacker. Connections using GCM
      or CCM instead of CBC, using hash sizes other than SHA-384, or using
      Encrypt-then-Mac (RFC 7366) were not affected. The vulnerability was
      caused by a miscalculation (for SHA-384) in a countermeasure to the
      original Lucky 13 attack. Found by Kenny Paterson, Eyal Ronen and Adi
      Shamir.
    * Fix a vulnerability in TLS ciphersuites based on CBC, in (D)TLS 1.0 to
      1.2, that allowed a local attacker, able to execute code on the local
      machine as well as manipulate network packets, to partially recover the
      plaintext of messages under some conditions by using a cache attack
      targeting an internal MD/SHA buffer. With TLS or if
      mbedtls_ssl_conf_dtls_badmac_limit() was used, the attack only worked if
      the same secret (for example a HTTP Cookie) has been repeatedly sent over
      connections manipulated by the attacker. Connections using GCM or CCM
      instead of CBC or using Encrypt-then-Mac (RFC 7366) were not affected.
      Found by Kenny Paterson, Eyal Ronen and Adi Shamir.
    * Add a counter-measure against a vulnerability in TLS ciphersuites based
      on CBC, in (D)TLS 1.0 to 1.2, that allowed a local attacker, able to
      execute code on the local machine as well as manipulate network packets,
      to partially recover the plaintext of messages under some conditions (see
      previous entry) by using a cache attack targeting the SSL input record
      buffer. Connections using GCM or CCM instead of CBC or using
      Encrypt-then-Mac (RFC 7366) were not affected. Found by Kenny Paterson,
      Eyal Ronen and Adi Shamir.
 
 Features
    * Add new crypto primitives from RFC 7539: stream cipher Chacha20, one-time
      authenticator Poly1305 and AEAD construct Chacha20-Poly1305. Contributed
      by Daniel King.
    * Add support for CHACHA20-POLY1305 ciphersuites from RFC 7905.
    * Add platform support for the Haiku OS. (https://www.haiku-os.org).
      Contributed by Augustin Cavalier.
    * Make the receive and transmit buffers independent sizes, for situations
      where the outgoing buffer can be fixed at a smaller size than the incoming
      buffer, which can save some RAM. If buffer lengths are kept equal, there
      is no functional difference. Contributed by Angus Gratton, and also
      independently contributed again by Paul Sokolovsky.
    * Add support for key wrapping modes based on AES as defined by
      NIST SP 800-38F algorithms KW and KWP and by RFC 3394 and RFC 5649.
 
 Bugfix
    * Fix the key_app_writer example which was writing a leading zero byte which
      was creating an invalid ASN.1 tag. Found by Aryeh R. Fixes #1257.
    * Fix compilation error on C++, because of a variable named new.
      Found and fixed by Hirotaka Niisato in #1783.
    * Fix "no symbols" warning issued by ranlib when building on Mac OS X. Fix
      contributed by tabascoeye.
    * Clarify documentation for mbedtls_ssl_write() to include 0 as a valid
      return value. Found by @davidwu2000. #839
    * Fix a memory leak in mbedtls_x509_csr_parse(), found by catenacyber,
      Philippe Antoine. Fixes #1623.
    * Remove unused headers included in x509.c. Found by Chris Hanson and fixed
      by Brendan Shanks. Part of a fix for #992.
    * Fix compilation error when MBEDTLS_ARC4_C is disabled and
      MBEDTLS_CIPHER_NULL_CIPHER is enabled. Found by TrinityTonic in #1719.
    * Added length checks to some TLS parsing functions. Found and fixed by
      Philippe Antoine from Catena cyber. #1663.
    * Fix the inline assembly for the MPI multiply helper function for i386 and
      i386 with SSE2. Found by László Langó. Fixes #1550
    * Fix namespacing in header files. Remove the `mbedtls` namespacing in
      the `#include` in the header files. Resolves #857
    * Fix compiler warning of 'use before initialisation' in
      mbedtls_pk_parse_key(). Found by Martin Boye Petersen and fixed by Dawid
      Drozd. #1098
    * Fix decryption for zero length messages (which contain all padding) when a
      CBC based ciphersuite is used together with Encrypt-then-MAC. Previously,
      such a message was wrongly reported as an invalid record and therefore lead
      to the connection being terminated. Seen most often with OpenSSL using
      TLS 1.0. Reported by @kFYatek and by Conor Murphy on the forum. Fix
      contributed by Espressif Systems. Fixes #1632
    * Fix ssl_client2 example to send application data with 0-length content
      when the request_size argument is set to 0 as stated in the documentation.
      Fixes #1833.
    * Correct the documentation for `mbedtls_ssl_get_session()`. This API has
      deep copy of the session, and the peer certificate is not lost. Fixes #926.
    * Fix build using -std=c99. Fixed by Nick Wilson.
 
 Changes
    * Fail when receiving a TLS alert message with an invalid length, or invalid
      zero-length messages when using TLS 1.2. Contributed by Espressif Systems.
    * Change the default behaviour of mbedtls_hkdf_extract() to return an error
      when calling with a NULL salt and non-zero salt_len. Contributed by
      Brian J Murray
    * Change the shebang line in Perl scripts to look up perl in the PATH.
      Contributed by fbrosson.
    * Allow overriding the time on Windows via the platform-time abstraction.
      Fixed by Nick Wilson.
    * Use gmtime_r/gmtime_s for thread-safety. Fixed by Nick Wilson.
 
 = mbed TLS 2.11.0 branch released 2018-06-18
 
 Features
    * Add additional block mode, OFB (Output Feedback), to the AES module and
      cipher abstraction module.
    * Implement the HMAC-based extract-and-expand key derivation function
      (HKDF) per RFC 5869. Contributed by Thomas Fossati.
    * Add support for the CCM* block cipher mode as defined in IEEE Std. 802.15.4.
    * Add support for the XTS block cipher mode with AES (AES-XTS).
      Contributed by Aorimn in pull request #414.
    * In TLS servers, support offloading private key operations to an external
      cryptoprocessor. Private key operations can be asynchronous to allow
      non-blocking operation of the TLS server stack.
 
 Bugfix
    * Fix the cert_write example to handle certificates signed with elliptic
      curves as well as RSA. Fixes #777 found by dbedev.
    * Fix for redefinition of _WIN32_WINNT to avoid overriding a definition
      used by user applications. Found and fixed by Fabio Alessandrelli.
    * Fix compilation warnings with IAR toolchain, on 32 bit platform.
      Reported by rahmanih in #683
    * Fix braces in mbedtls_memory_buffer_alloc_status(). Found by sbranden, #552.
 
 Changes
    * Changed CMake defaults for IAR to treat all compiler warnings as errors.
    * Changed the Clang parameters used in the CMake build files to work for
      versions later than 3.6. Versions of Clang earlier than this may no longer
      work. Fixes #1072
 
 = mbed TLS 2.10.0 branch released 2018-06-06
 
 Features
    * Add support for ARIA cipher (RFC 5794) and associated TLS ciphersuites
      (RFC 6209). Disabled by default, see MBEDTLS_ARIA_C in config.h
 
 API Changes
    * Extend the platform module with a util component that contains
      functionality shared by multiple Mbed TLS modules. At this stage
      platform_util.h (and its associated platform_util.c) only contain
      mbedtls_platform_zeroize(), which is a critical function from a security
      point of view. mbedtls_platform_zeroize() needs to be regularly tested
      against compilers to ensure that calls to it are not removed from the
      output binary as part of redundant code elimination optimizations.
      Therefore, mbedtls_platform_zeroize() is moved to the platform module to
      facilitate testing and maintenance.
 
 Bugfix
    * Fix an issue with MicroBlaze support in bn_mul.h which was causing the
      build to fail. Found by zv-io. Fixes #1651.
 
 Changes
    * Support TLS testing in out-of-source builds using cmake. Fixes #1193.
    * Fix redundant declaration of mbedtls_ssl_list_ciphersuites. Raised by
      TrinityTonic. #1359.
 
 = mbed TLS 2.9.0 branch released 2018-04-30
 
 Security
    * Fix an issue in the X.509 module which could lead to a buffer overread
      during certificate validation. Additionally, the issue could also lead to
      unnecessary callback checks being made or to some validation checks to be
      omitted. The overread could be triggered remotely, while the other issues
      would require a non DER-compliant certificate to be correctly signed by a
      trusted CA, or a trusted CA with a non DER-compliant certificate. Found by
      luocm. Fixes #825.
    * Fix the buffer length assertion in the ssl_parse_certificate_request()
      function which led to an arbitrary overread of the message buffer. The
      overreads could be caused by receiving a malformed message at the point
      where an optional signature algorithms list is expected when the signature
      algorithms section is too short. In builds with debug output, the overread
      data is output with the debug data.
    * Fix a client-side bug in the validation of the server's ciphersuite choice
      which could potentially lead to the client accepting a ciphersuite it didn't
      offer or a ciphersuite that cannot be used with the TLS or DTLS version
      chosen by the server. This could lead to corruption of internal data
      structures for some configurations.
 
 Features
    * Add an option, MBEDTLS_AES_FEWER_TABLES, to dynamically compute smaller AES
      tables during runtime, thereby reducing the RAM/ROM footprint by ~6KiB.
      Suggested and contributed by jkivilin in pull request #394.
    * Add initial support for Curve448 (RFC 7748). Only mbedtls_ecp_mul() and
      ECDH primitive functions (mbedtls_ecdh_gen_public(),
      mbedtls_ecdh_compute_shared()) are supported for now. Contributed by
      Nicholas Wilson in pull request #348.
 
 API Changes
    * Extend the public API with the function of mbedtls_net_poll() to allow user
      applications to wait for a network context to become ready before reading
      or writing.
    * Add function mbedtls_ssl_check_pending() to the public API to allow
      a check for whether more more data is pending to be processed in the
      internal message buffers.
      This function is necessary to determine when it is safe to idle on the
      underlying transport in case event-driven IO is used.
 
 Bugfix
    * Fix a spurious uninitialized variable warning in cmac.c. Fix independently
      contributed by Brian J Murray and David Brown.
    * Add missing dependencies in test suites that led to build failures
      in configurations that omit certain hashes or public-key algorithms.
      Fixes #1040.
    * Fix C89 incompatibility in benchmark.c. Contributed by Brendan Shanks.
      #1353
    * Add missing dependencies for MBEDTLS_HAVE_TIME_DATE and
      MBEDTLS_VERSION_FEATURES in some test suites. Contributed by
      Deomid Ryabkov. Fixes #1299, #1475.
    * Fix the Makefile build process for building shared libraries on Mac OS X.
      Fixed by mnacamura.
    * Fix parsing of PKCS#8 encoded Elliptic Curve keys. Previously Mbed TLS was
      unable to parse keys which had only the optional parameters field of the
      ECPrivateKey structure. Found by Jethro Beekman, fixed in #1379.
    * Return the plaintext data more quickly on unpadded CBC decryption, as
      stated in the mbedtls_cipher_update() documentation. Contributed by
      Andy Leiserson.
    * Fix overriding and ignoring return values when parsing and writing to
      a file in pk_sign program. Found by kevlut in #1142.
    * Restrict usage of error code MBEDTLS_ERR_SSL_WANT_READ to situations
      where data needs to be fetched from the underlying transport in order
      to make progress. Previously, this error code was also occasionally
      returned when unexpected messages were being discarded, ignoring that
      further messages could potentially already be pending to be processed
      in the internal buffers; these cases led to deadlocks when event-driven
      I/O was used. Found and reported by Hubert Mis in #772.
    * Fix buffer length assertions in the ssl_parse_certificate_request()
      function which leads to a potential one byte overread of the message
      buffer.
    * Fix invalid buffer sizes passed to zlib during record compression and
      decompression.
    * Fix the soversion of libmbedcrypto to match the soversion of the
      maintained 2.7 branch. The soversion was increased in Mbed TLS
      version 2.7.1 to reflect breaking changes in that release, but the
      increment was missed in 2.8.0 and later releases outside of the 2.7 branch.
 
 Changes
    * Remove some redundant code in bignum.c. Contributed by Alexey Skalozub.
    * Support cmake builds where Mbed TLS is a subproject. Fix contributed
      independently by Matthieu Volat and Arne Schwabe.
    * Improve testing in configurations that omit certain hashes or
      public-key algorithms. Includes contributions by Gert van Dijk.
    * Improve negative testing of X.509 parsing.
    * Do not define global mutexes around readdir() and gmtime() in
      configurations where the feature is disabled. Found and fixed by Gergely
      Budai.
    * Harden the function mbedtls_ssl_config_free() against misuse, so that it
      doesn't leak memory if the user doesn't use mbedtls_ssl_conf_psk() and
      instead incorrectly manipulates the configuration structure directly.
      Found and fix submitted by junyeonLEE in #1220.
    * Provide an empty implementation of mbedtls_pkcs5_pbes2() when
      MBEDTLS_ASN1_PARSE_C is not enabled. This allows the use of PBKDF2
      without PBES2. Fixed by Marcos Del Sol Vives.
    * Add the order of the base point as N in the mbedtls_ecp_group structure
      for Curve25519 (other curves had it already). Contributed by Nicholas
      Wilson #481
    * Improve the documentation of mbedtls_net_accept(). Contributed by Ivan
      Krylov.
    * Improve the documentation of mbedtls_ssl_write(). Suggested by
      Paul Sokolovsky in #1356.
    * Add an option in the Makefile to support ar utilities where the operation
      letter must not be prefixed by '-', such as LLVM. Found and fixed by
      Alex Hixon.
    * Allow configuring the shared library extension by setting the DLEXT
      environment variable when using the project makefiles.
    * Optimize unnecessary zeroing in mbedtls_mpi_copy. Based on a contribution
      by Alexey Skalozub in #405.
    * In the SSL module, when f_send, f_recv or f_recv_timeout report
      transmitting more than the required length, return an error. Raised by
      Sam O'Connor in #1245.
    * Improve robustness of mbedtls_ssl_derive_keys against the use of
      HMAC functions with non-HMAC ciphersuites. Independently contributed
      by Jiayuan Chen in #1377. Fixes #1437.
    * Improve security of RSA key generation by including criteria from
      FIPS 186-4. Contributed by Jethro Beekman. #1380
    * Declare functions in header files even when an alternative implementation
      of the corresponding module is activated by defining the corresponding
      MBEDTLS_XXX_ALT macro. This means that alternative implementations do
      not need to copy the declarations, and ensures that they will have the
      same API.
    * Add platform setup and teardown calls in test suites.
 
 = mbed TLS 2.8.0 branch released 2018-03-16
 
 Default behavior changes
    * The truncated HMAC extension now conforms to RFC 6066. This means
      that when both sides of a TLS connection negotiate the truncated
      HMAC extension, Mbed TLS can now interoperate with other
      compliant implementations, but this breaks interoperability with
      prior versions of Mbed TLS. To restore the old behavior, enable
      the (deprecated) option MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT in
      config.h. Found by Andreas Walz (ivESK, Offenburg University of
      Applied Sciences).
 
 Security
    * Fix implementation of the truncated HMAC extension. The previous
      implementation allowed an offline 2^80 brute force attack on the
      HMAC key of a single, uninterrupted connection (with no
      resumption of the session).
    * Verify results of RSA private key operations to defend
      against Bellcore glitch attack.
    * Fix a buffer overread in ssl_parse_server_key_exchange() that could cause
      a crash on invalid input.
    * Fix a buffer overread in ssl_parse_server_psk_hint() that could cause a
      crash on invalid input.
    * Fix CRL parsing to reject CRLs containing unsupported critical
      extensions. Found by Falko Strenzke and Evangelos Karatsiolis.
 
 Features
    * Extend PKCS#8 interface by introducing support for the entire SHA
      algorithms family when encrypting private keys using PKCS#5 v2.0.
      This allows reading encrypted PEM files produced by software that
      uses PBKDF2-SHA2, such as OpenSSL 1.1. Submitted by Antonio Quartulli,
      OpenVPN Inc. Fixes #1339
    * Add support for public keys encoded in PKCS#1 format. #1122
 
 New deprecations
    * Deprecate support for record compression (configuration option
      MBEDTLS_ZLIB_SUPPORT).
 
 Bugfix
    * Fix the name of a DHE parameter that was accidentally changed in 2.7.0.
      Fixes #1358.
    * Fix test_suite_pk to work on 64-bit ILP32 systems. #849
    * Fix mbedtls_x509_crt_profile_suiteb, which used to reject all certificates
      with flag MBEDTLS_X509_BADCERT_BAD_PK even when the key type was correct.
      In the context of SSL, this resulted in handshake failure. Reported by
      daniel in the Mbed TLS forum. #1351
    * Fix Windows x64 builds with the included mbedTLS.sln file. #1347
    * Fix setting version TLSv1 as minimal version, even if TLS 1
      is not enabled. Set MBEDTLS_SSL_MIN_MAJOR_VERSION
      and MBEDTLS_SSL_MIN_MINOR_VERSION instead of
      MBEDTLS_SSL_MAJOR_VERSION_3 and MBEDTLS_SSL_MINOR_VERSION_1. #664
    * Fix compilation error on Mingw32 when _TRUNCATE is defined. Use _TRUNCATE
      only if __MINGW32__ not defined. Fix suggested by Thomas Glanzmann and
      Nick Wilson on issue #355
    * In test_suite_pk, pass valid parameters when testing for hash length
      overflow. #1179
    * Fix memory allocation corner cases in memory_buffer_alloc.c module. Found
      by Guido Vranken. #639
    * Log correct number of ciphersuites used in Client Hello message. #918
    * Fix X509 CRT parsing that would potentially accept an invalid tag when
      parsing the subject alternative names.
    * Fix a possible arithmetic overflow in ssl_parse_server_key_exchange()
      that could cause a key exchange to fail on valid data.
    * Fix a possible arithmetic overflow in ssl_parse_server_psk_hint() that
      could cause a key exchange to fail on valid data.
    * Don't define mbedtls_aes_decrypt and mbedtls_aes_encrypt under
      MBEDTLS_DEPRECATED_REMOVED. #1388
    * Fix a 1-byte heap buffer overflow (read-only) during private key parsing.
      Found through fuzz testing.
 
 Changes
    * Fix tag lengths and value ranges in the documentation of CCM encryption.
      Contributed by Mathieu Briand.
    * Fix typo in a comment ctr_drbg.c. Contributed by Paul Sokolovsky.
    * Remove support for the library reference configuration for picocoin.
    * MD functions deprecated in 2.7.0 are no longer inline, to provide
      a migration path for those depending on the library's ABI.
    * Clarify the documentation of mbedtls_ssl_setup.
    * Use (void) when defining functions with no parameters. Contributed by
      Joris Aerts. #678
 
 = mbed TLS 2.7.0 branch released 2018-02-03
 
 Security
    * Fix a heap corruption issue in the implementation of the truncated HMAC
      extension. When the truncated HMAC extension is enabled and CBC is used,
      sending a malicious application packet could be used to selectively corrupt
      6 bytes on the peer's heap, which could potentially lead to crash or remote
      code execution. The issue could be triggered remotely from either side in
      both TLS and DTLS. CVE-2018-0488
    * Fix a buffer overflow in RSA-PSS verification when the hash was too large
      for the key size, which could potentially lead to crash or remote code
      execution. Found by Seth Terashima, Qualcomm Product Security Initiative,
      Qualcomm Technologies Inc. CVE-2018-0487
    * Fix buffer overflow in RSA-PSS verification when the unmasked data is all
      zeros.
    * Fix an unsafe bounds check in ssl_parse_client_psk_identity() when adding
      64 KiB to the address of the SSL buffer and causing a wrap around.
    * Fix a potential heap buffer overflow in mbedtls_ssl_write(). When the (by
      default enabled) maximum fragment length extension is disabled in the
      config and the application data buffer passed to mbedtls_ssl_write
      is larger than the internal message buffer (16384 bytes by default), the
      latter overflows. The exploitability of this issue depends on whether the
      application layer can be forced into sending such large packets. The issue
      was independently reported by Tim Nordell via e-mail and by Florin Petriuc
      and sjorsdewit on GitHub. Fix proposed by Florin Petriuc in #1022.
      Fixes #707.
    * Add a provision to prevent compiler optimizations breaking the time
      constancy of mbedtls_ssl_safer_memcmp().
    * Ensure that buffers are cleared after use if they contain sensitive data.
      Changes were introduced in multiple places in the library.
    * Set PEM buffer to zero before freeing it, to avoid decoded private keys
      being leaked to memory after release.
    * Fix dhm_check_range() failing to detect trivial subgroups and potentially
      leaking 1 bit of the private key. Reported by prashantkspatil.
    * Make mbedtls_mpi_read_binary() constant-time with respect to the input
      data. Previously, trailing zero bytes were detected and omitted for the
      sake of saving memory, but potentially leading to slight timing
      differences. Reported by Marco Macchetti, Kudelski Group.
    * Wipe stack buffer temporarily holding EC private exponent
      after keypair generation.
    * Fix a potential heap buffer over-read in ALPN extension parsing
      (server-side). Could result in application crash, but only if an ALPN
      name larger than 16 bytes had been configured on the server.
    * Change default choice of DHE parameters from untrustworthy RFC 5114
      to RFC 3526 containing parameters generated in a nothing-up-my-sleeve
      manner.
 
 Features
    * Allow comments in test data files.
    * The selftest program can execute a subset of the tests based on command
      line arguments.
    * New unit tests for timing. Improve the self-test to be more robust
      when run on a heavily-loaded machine.
    * Add alternative implementation support for CCM and CMAC (MBEDTLS_CCM_ALT,
      MBEDTLS_CMAC_ALT). Submitted by Steven Cooreman, Silicon Labs.
    * Add support for alternative implementations of GCM, selected by the
      configuration flag MBEDTLS_GCM_ALT.
    * Add support for alternative implementations for ECDSA, controlled by new
      configuration flags MBEDTLS_ECDSA_SIGN_ALT, MBEDTLS_ECDSA_VERIFY_ALT and
      MBEDTLS_ECDSDA_GENKEY_AT in config.h.
      The following functions from the ECDSA module can be replaced
      with alternative implementation:
      mbedtls_ecdsa_sign(), mbedtls_ecdsa_verify() and mbedtls_ecdsa_genkey().
    * Add support for alternative implementation of ECDH, controlled by the
      new configuration flags MBEDTLS_ECDH_COMPUTE_SHARED_ALT and
      MBEDTLS_ECDH_GEN_PUBLIC_ALT in config.h.
      The following functions from the ECDH module can be replaced
      with an alternative implementation:
      mbedtls_ecdh_gen_public() and mbedtls_ecdh_compute_shared().
    * Add support for alternative implementation of ECJPAKE, controlled by
      the new configuration flag MBEDTLS_ECJPAKE_ALT.
    * Add mechanism to provide alternative implementation of the DHM module.
 
 API Changes
    * Extend RSA interface by multiple functions allowing structure-
      independent setup and export of RSA contexts. Most notably,
      mbedtls_rsa_import() and mbedtls_rsa_complete() are introduced for setting
      up RSA contexts from partial key material and having them completed to the
      needs of the implementation automatically. This allows to setup private RSA
      contexts from keys consisting of N,D,E only, even if P,Q are needed for the
      purpose or CRT and/or blinding.
    * The configuration option MBEDTLS_RSA_ALT can be used to define alternative
      implementations of the RSA interface declared in rsa.h.
    * The following functions in the message digest modules (MD2, MD4, MD5,
      SHA1, SHA256, SHA512) have been deprecated and replaced as shown below.
      The new functions change the return type from void to int to allow
      returning error codes when using MBEDTLS_<MODULE>_ALT.
      mbedtls_<MODULE>_starts() -> mbedtls_<MODULE>_starts_ret()
      mbedtls_<MODULE>_update() -> mbedtls_<MODULE>_update_ret()
      mbedtls_<MODULE>_finish() -> mbedtls_<MODULE>_finish_ret()
      mbedtls_<MODULE>_process() -> mbedtls_internal_<MODULE>_process()
 
 New deprecations
    * Deprecate usage of RSA primitives with non-matching key-type
      (e.g. signing with a public key).
    * Direct manipulation of structure fields of RSA contexts is deprecated.
      Users are advised to use the extended RSA API instead.
    * Deprecate usage of message digest functions that return void
      (mbedtls_<MODULE>_starts, mbedtls_<MODULE>_update,
      mbedtls_<MODULE>_finish and mbedtls_<MODULE>_process where <MODULE> is
      any of MD2, MD4, MD5, SHA1, SHA256, SHA512) in favor of functions
      that can return an error code.
    * Deprecate untrustworthy DHE parameters from RFC 5114. Superseded by
      parameters from RFC 3526 or the newly added parameters from RFC 7919.
    * Deprecate hex string DHE constants MBEDTLS_DHM_RFC3526_MODP_2048_P etc.
      Supserseded by binary encoded constants MBEDTLS_DHM_RFC3526_MODP_2048_P_BIN
      etc.
    * Deprecate mbedtls_ssl_conf_dh_param() for setting default DHE parameters
      from hex strings. Superseded by mbedtls_ssl_conf_dh_param_bin()
      accepting DHM parameters in binary form, matching the new constants.
 
 Bugfix
    * Fix ssl_parse_record_header() to silently discard invalid DTLS records
      as recommended in RFC 6347 Section 4.1.2.7.
    * Fix memory leak in mbedtls_ssl_set_hostname() when called multiple times.
      Found by projectgus and Jethro Beekman, #836.
    * Fix usage help in ssl_server2 example. Found and fixed by Bei Lin.
    * Parse signature algorithm extension when renegotiating. Previously,
      renegotiated handshakes would only accept signatures using SHA-1
      regardless of the peer's preferences, or fail if SHA-1 was disabled.
    * Fix leap year calculation in x509_date_is_valid() to ensure that invalid
      dates on leap years with 100 and 400 intervals are handled correctly. Found
      by Nicholas Wilson. #694
    * Fix some invalid RSA-PSS signatures with keys of size 8N+1 that were
      accepted. Generating these signatures required the private key.
    * Fix out-of-memory problem when parsing 4096-bit PKCS8-encrypted RSA keys.
      Found independently by Florian in the mbed TLS forum and by Mishamax.
      #878, #1019.
    * Fix variable used before assignment compilation warnings with IAR
      toolchain. Found by gkerrien38.
    * Fix unchecked return codes from AES, DES and 3DES functions in
      pem_aes_decrypt(), pem_des_decrypt() and pem_des3_decrypt() respectively.
      If a call to one of the functions of the cryptographic primitive modules
      failed, the error may not be noticed by the function
      mbedtls_pem_read_buffer() causing it to return invalid values. Found by
      Guido Vranken. #756
    * Include configuration file in md.h, to fix compilation warnings.
      Reported by aaronmdjones in #1001
    * Correct extraction of signature-type from PK instance in X.509 CRT and CSR
      writing routines that prevented these functions to work with alternative
      RSA implementations. Raised by J.B. in the Mbed TLS forum. Fixes #1011.
    * Don't print X.509 version tag for v1 CRT's, and omit extensions for
      non-v3 CRT's.
    * Fix bugs in RSA test suite under MBEDTLS_NO_PLATFORM_ENTROPY. #1023 #1024
    * Fix net_would_block() to avoid modification by errno through fcntl() call.
      Found by nkolban. Fixes #845.
    * Fix handling of handshake messages in mbedtls_ssl_read() in case
      MBEDTLS_SSL_RENEGOTIATION is disabled. Found by erja-gp.
    * Add a check for invalid private parameters in mbedtls_ecdsa_sign().
      Reported by Yolan Romailler.
    * Fix word size check in in pk.c to not depend on MBEDTLS_HAVE_INT64.
    * Fix incorrect unit in benchmark output. #850
    * Add size-checks for record and handshake message content, securing
      fragile yet non-exploitable code-paths.
    * Fix crash when calling mbedtls_ssl_cache_free() twice. Found by
      MilenkoMitrovic, #1104
    * Fix mbedtls_timing_alarm(0) on Unix and MinGW.
    * Fix use of uninitialized memory in mbedtls_timing_get_timer() when reset=1.
    * Fix possible memory leaks in mbedtls_gcm_self_test().
    * Added missing return code checks in mbedtls_aes_self_test().
    * Fix issues in RSA key generation program programs/x509/rsa_genkey and the
      RSA test suite where the failure of CTR DRBG initialization lead to
      freeing an RSA context and several MPI's without proper initialization
      beforehand.
    * Fix error message in programs/pkey/gen_key.c. Found and fixed by Chris Xue.
    * Fix programs/pkey/dh_server.c so that it actually works with dh_client.c.
      Found and fixed by Martijn de Milliano.
    * Fix an issue in the cipher decryption with the mode
      MBEDTLS_PADDING_ONE_AND_ZEROS that sometimes accepted invalid padding.
      Note, this padding mode is not used by the TLS protocol. Found and fixed by
      Micha Kraus.
    * Fix the entropy.c module to not call mbedtls_sha256_starts() or
      mbedtls_sha512_starts() in the mbedtls_entropy_init() function.
    * Fix the entropy.c module to ensure that mbedtls_sha256_init() or
      mbedtls_sha512_init() is called before operating on the relevant context
      structure. Do not assume that zeroizing a context is a correct way to
      reset it. Found independently by ccli8 on Github.
    * In mbedtls_entropy_free(), properly free the message digest context.
    * Fix status handshake status message in programs/ssl/dtls_client.c. Found
      and fixed by muddog.
 
 Changes
    * Extend cert_write example program by options to set the certificate version
      and the message digest. Further, allow enabling/disabling of authority
      identifier, subject identifier and basic constraints extensions.
    * Only check for necessary RSA structure fields in `mbedtls_rsa_private`. In
      particular, don't require P,Q if neither CRT nor blinding are
      used. Reported and fix proposed independently by satur9nine and sliai
      on GitHub.
    * Only run AES-192 self-test if AES-192 is available. Fixes #963.
    * Tighten the RSA PKCS#1 v1.5 signature verification code and remove the
      undeclared dependency of the RSA module on the ASN.1 module.
    * Update all internal usage of deprecated message digest functions to the
      new ones with return codes. In particular, this modifies the
      mbedtls_md_info_t structure. Propagate errors from these functions
      everywhere except some locations in the ssl_tls.c module.
    * Improve CTR_DRBG error handling by propagating underlying AES errors.
    * Add MBEDTLS_ERR_XXX_HW_ACCEL_FAILED error codes for all cryptography
      modules where the software implementation can be replaced by a hardware
      implementation.
    * Add explicit warnings for the use of MD2, MD4, MD5, SHA-1, DES and ARC4
      throughout the library.
 
 = mbed TLS 2.6.0 branch released 2017-08-10
 
 Security
    * Fix authentication bypass in SSL/TLS: when authmode is set to optional,
      mbedtls_ssl_get_verify_result() would incorrectly return 0 when the peer's
      X.509 certificate chain had more than MBEDTLS_X509_MAX_INTERMEDIATE_CA
      (default: 8) intermediates, even when it was not trusted. This could be
      triggered remotely from either side. (With authmode set to 'required'
      (the default), the handshake was correctly aborted).
    * Reliably wipe sensitive data after use in the AES example applications
      programs/aes/aescrypt2 and programs/aes/crypt_and_hash.
      Found by Laurent Simon.
 
 Features
    * Add the functions mbedtls_platform_setup() and mbedtls_platform_teardown()
      and the context struct mbedtls_platform_context to perform
      platform-specific setup and teardown operations. The macro
      MBEDTLS_PLATFORM_SETUP_TEARDOWN_ALT allows the functions to be overridden
      by the user in a platform_alt.h file. These new functions are required in
      some embedded environments to provide a means of initialising underlying
      cryptographic acceleration hardware.
 
 API Changes
    * Reverted API/ABI breaking changes introduced in mbed TLS 2.5.1, to make the
      API consistent with mbed TLS 2.5.0. Specifically removed the inline
      qualifier from the functions mbedtls_aes_decrypt, mbedtls_aes_encrypt,
      mbedtls_ssl_ciphersuite_uses_ec and mbedtls_ssl_ciphersuite_uses_psk. Found
      by James Cowgill. #978
    * Certificate verification functions now set flags to -1 in case the full
      chain was not verified due to an internal error (including in the verify
      callback) or chain length limitations.
    * With authmode set to optional, the TLS handshake is now aborted if the
      verification of the peer's certificate failed due to an overlong chain or
      a fatal error in the verify callback.
 
 Bugfix
    * Add a check if iv_len is zero in GCM, and return an error if it is zero.
      Reported by roberto. #716
    * Replace preprocessor condition from #if defined(MBEDTLS_THREADING_PTHREAD)
      to #if defined(MBEDTLS_THREADING_C) as the library cannot assume they will
      always be implemented by pthread support. #696
    * Fix a resource leak on Windows platforms in mbedtls_x509_crt_parse_path(),
      in the case of an error. Found by redplait. #590
    * Add MBEDTLS_MPI_CHK to check for error value of mbedtls_mpi_fill_random.
      Reported and fix suggested by guidovranken. #740
    * Fix conditional preprocessor directives in bignum.h to enable 64-bit
      compilation when using ARM Compiler 6.
    * Fix a potential integer overflow in the version verification for DER
      encoded X.509 CRLs. The overflow could enable maliciously constructed CRLs
      to bypass the version verification check. Found by Peng Li/Yueh-Hsun Lin,
      KNOX Security, Samsung Research America
    * Fix potential integer overflow in the version verification for DER
      encoded X.509 CSRs. The overflow could enable maliciously constructed CSRs
      to bypass the version verification check. Found by Peng Li/Yueh-Hsun Lin,
      KNOX Security, Samsung Research America
    * Fix a potential integer overflow in the version verification for DER
      encoded X.509 certificates. The overflow could enable maliciously
      constructed certificates to bypass the certificate verification check.
    * Fix a call to the libc function time() to call the platform abstraction
      function mbedtls_time() instead. Found by wairua. #666
    * Avoid shadowing of time and index functions through mbed TLS function
      arguments. Found by inestlerode. #557.
 
 Changes
    * Added config.h option MBEDTLS_NO_UDBL_DIVISION, to prevent the use of
      64-bit division. This is useful on embedded platforms where 64-bit division
      created a dependency on external libraries. #708
    * Removed mutexes from ECP hardware accelerator code. Now all hardware
      accelerator code in the library leaves concurrency handling to the
      platform. Reported by Steven Cooreman. #863
    * Define the macro MBEDTLS_AES_ROM_TABLES in the configuration file
      config-no-entropy.h to reduce the RAM footprint.
    * Added a test script that can be hooked into git that verifies commits
      before they are pushed.
    * Improve documentation of PKCS1 decryption functions.
 
 = mbed TLS 2.5.1 released 2017-06-21
 
 Security
    * Fixed unlimited overread of heap-based buffer in mbedtls_ssl_read().
      The issue could only happen client-side with renegotiation enabled.
      Could result in DoS (application crash) or information leak
      (if the application layer sent data read from mbedtls_ssl_read()
      back to the server or to a third party). Can be triggered remotely.
    * Removed SHA-1 and RIPEMD-160 from the default hash algorithms for
      certificate verification. SHA-1 can be turned back on with a compile-time
      option if needed.
    * Fixed offset in FALLBACK_SCSV parsing that caused TLS server to fail to
      detect it sometimes. Reported by Hugo Leisink. #810
    * Tighten parsing of RSA PKCS#1 v1.5 signatures, to avoid a
      potential Bleichenbacher/BERserk-style attack.
 
 Bugfix
    * Remove size zero arrays from ECJPAKE test suite. Size zero arrays are not
      valid C and they prevented the test from compiling in Visual Studio 2015
      and with GCC using the -Wpedantic compilation option.
    * Fix insufficient support for signature-hash-algorithm extension,
      resulting in compatibility problems with Chrome. Found by hfloyrd. #823
    * Fix behaviour that hid the original cause of fatal alerts in some cases
      when sending the alert failed. The fix makes sure not to hide the error
      that triggered the alert.
    * Fix SSLv3 renegotiation behaviour and stop processing data received from
      peer after sending a fatal alert to refuse a renegotiation attempt.
      Previous behaviour was to keep processing data even after the alert has
      been sent.
    * Accept empty trusted CA chain in authentication mode
      MBEDTLS_SSL_VERIFY_OPTIONAL. Found by Jethro Beekman. #864
    * Fix implementation of mbedtls_ssl_parse_certificate() to not annihilate
      fatal errors in authentication mode MBEDTLS_SSL_VERIFY_OPTIONAL and to
      reflect bad EC curves within verification result.
    * Fix bug that caused the modular inversion function to accept the invalid
      modulus 1 and therefore to hang. Found by blaufish. #641.
    * Fix incorrect sign computation in modular exponentiation when the base is
      a negative MPI. Previously the result was always negative. Found by Guido
      Vranken.
    * Fix a numerical underflow leading to stack overflow in mpi_read_file()
      that was triggered uppon reading an empty line. Found by Guido Vranken.
 
 Changes
    * Send fatal alerts in more cases. The previous behaviour was to skip
      sending the fatal alert and just drop the connection.
    * Clarify ECDSA documentation and improve the sample code to avoid
      misunderstanding and potentially dangerous use of the API. Pointed out
      by Jean-Philippe Aumasson.
 
 = mbed TLS 2.5.0 branch released 2017-05-17
 
 Security
    * Wipe stack buffers in RSA private key operations
      (rsa_rsaes_pkcs1_v15_decrypt(), rsa_rsaes_oaep_decrypt). Found by Laurent
      Simon.
    * Add exponent blinding to RSA private operations as a countermeasure
      against side-channel attacks like the cache attack described in
      https://arxiv.org/abs/1702.08719v2.
      Found and fix proposed by Michael Schwarz, Samuel Weiser, Daniel Gruss,
      Clémentine Maurice and Stefan Mangard.
 
 Features
    * Add hardware acceleration support for the Elliptic Curve Point module.
      This involved exposing parts of the internal interface to enable
      replacing the core functions and adding and alternative, module level
      replacement support for enabling the extension of the interface.
    * Add a new configuration option to 'mbedtls_ssl_config' to enable
      suppressing the CA list in Certificate Request messages. The default
      behaviour has not changed, namely every configured CAs name is included.
 
 API Changes
    * The following functions in the AES module have been deprecated and replaced
      by the functions shown below. The new functions change the return type from
      void to int to allow returning error codes when using MBEDTLS_AES_ALT,
      MBEDTLS_AES_DECRYPT_ALT or MBEDTLS_AES_ENCRYPT_ALT.
      mbedtls_aes_decrypt() -> mbedtls_internal_aes_decrypt()
      mbedtls_aes_encrypt() -> mbedtls_internal_aes_encrypt()
 
 Bugfix
    * Remove macros from compat-1.3.h that correspond to deleted items from most
      recent versions of the library. Found by Kyle Keen.
    * Fixed issue in the Threading module that prevented mutexes from
      initialising. Found by sznaider. #667 #843
    * Add checks in the PK module for the RSA functions on 64-bit systems.
      The PK and RSA modules use different types for passing hash length and
      without these checks the type cast could lead to data loss. Found by Guido
      Vranken.
 
 = mbed TLS 2.4.2 branch released 2017-03-08
 
 Security
    * Add checks to prevent signature forgeries for very large messages while
      using RSA through the PK module in 64-bit systems. The issue was caused by
      some data loss when casting a size_t to an unsigned int value in the
      functions rsa_verify_wrap(), rsa_sign_wrap(), rsa_alt_sign_wrap() and
      mbedtls_pk_sign(). Found by Jean-Philippe Aumasson.
    * Fixed potential livelock during the parsing of a CRL in PEM format in
      mbedtls_x509_crl_parse(). A string containing a CRL followed by trailing
      characters after the footer could result in the execution of an infinite
      loop. The issue can be triggered remotely. Found by Greg Zaverucha,
      Microsoft.
    * Removed MD5 from the allowed hash algorithms for CertificateRequest and
      CertificateVerify messages, to prevent SLOTH attacks against TLS 1.2.
      Introduced by interoperability fix for #513.
    * Fixed a bug that caused freeing a buffer that was allocated on the stack,
      when verifying the validity of a key on secp224k1. This could be
      triggered remotely for example with a maliciously constructed certificate
      and potentially could lead to remote code execution on some platforms.
      Reported independently by rongsaws and Aleksandar Nikolic, Cisco Talos
      team. #569 CVE-2017-2784
 
 Bugfix
    * Fix output certificate verification flags set by x509_crt_verify_top() when
      traversing a chain of trusted CA. The issue would cause both flags,
      MBEDTLS_X509_BADCERT_NOT_TRUSTED and MBEDTLS_X509_BADCERT_EXPIRED, to be
      set when the verification conditions are not met regardless of the cause.
      Found by Harm Verhagen and inestlerode. #665 #561
    * Fix the redefinition of macro ssl_set_bio to an undefined symbol
      mbedtls_ssl_set_bio_timeout in compat-1.3.h, by removing it.
      Found by omlib-lin. #673
    * Fix unused variable/function compilation warnings in pem.c, x509_crt.c and
      x509_csr.c that are reported when building mbed TLS with a config.h that
      does not define MBEDTLS_PEM_PARSE_C. Found by omnium21. #562
    * Fix incorrect renegotiation condition in ssl_check_ctr_renegotiate() that
      would compare 64 bits of the record counter instead of 48 bits as indicated
      in RFC 6347 Section 4.3.1. This could cause the execution of the
      renegotiation routines at unexpected times when the protocol is DTLS. Found
      by wariua. #687
    * Fixed multiple buffer overreads in mbedtls_pem_read_buffer() when parsing
      the input string in PEM format to extract the different components. Found
      by Eyal Itkin.
    * Fixed potential arithmetic overflow in mbedtls_ctr_drbg_reseed() that could
      cause buffer bound checks to be bypassed. Found by Eyal Itkin.
    * Fixed potential arithmetic overflows in mbedtls_cipher_update() that could
      cause buffer bound checks to be bypassed. Found by Eyal Itkin.
    * Fixed potential arithmetic overflow in mbedtls_md2_update() that could
      cause buffer bound checks to be bypassed. Found by Eyal Itkin.
    * Fixed potential arithmetic overflow in mbedtls_base64_decode() that could
      cause buffer bound checks to be bypassed. Found by Eyal Itkin.
    * Fixed heap overreads in mbedtls_x509_get_time(). Found by Peng
      Li/Yueh-Hsun Lin, KNOX Security, Samsung Research America.
    * Fix potential memory leak in mbedtls_x509_crl_parse(). The leak was caused
      by missing calls to mbedtls_pem_free() in cases when a
      MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT error was encountered. Found and
      fix proposed by Guido Vranken. #722
    * Fixed the templates used to generate project and solution files for Visual
      Studio 2015 as well as the files themselves, to remove a build warning
      generated in Visual Studio 2015. Reported by Steve Valliere. #742
    * Fix a resource leak in ssl_cookie, when using MBEDTLS_THREADING_C.
      Raised and fix suggested by Alan Gillingham in the mbed TLS forum. #771
    * Fix 1 byte buffer overflow in mbedtls_mpi_write_string() when the MPI
      number to write in hexadecimal is negative and requires an odd number of
      digits. Found and fixed by Guido Vranken.
    * Fix unlisted DES configuration dependency in some pkparse test cases. Found
      by inestlerode. #555
 
 = mbed TLS 2.4.1 branch released 2016-12-13
 
 Changes
    * Update to CMAC test data, taken from - NIST Special Publication 800-38B -
      Recommendation for Block Cipher Modes of Operation: The CMAC Mode for
      Authentication – October  2016
 
 = mbed TLS 2.4.0 branch released 2016-10-17
 
 Security
    * Removed the MBEDTLS_SSL_AEAD_RANDOM_IV option, because it was not compliant
      with RFC-5116 and could lead to session key recovery in very long TLS
      sessions. "Nonce-Disrespecting Adversaries Practical Forgery Attacks on GCM in
      TLS" - H. Bock, A. Zauner, S. Devlin, J. Somorovsky, P. Jovanovic.
      https://eprint.iacr.org/2016/475.pdf
    * Fixed potential stack corruption in mbedtls_x509write_crt_der() and
      mbedtls_x509write_csr_der() when the signature is copied to the buffer
      without checking whether there is enough space in the destination. The
      issue cannot be triggered remotely. Found by Jethro Beekman.
 
 Features
    * Added support for CMAC for AES and 3DES and AES-CMAC-PRF-128, as defined by
      NIST SP 800-38B, RFC-4493 and RFC-4615.
    * Added hardware entropy selftest to verify that the hardware entropy source
      is functioning correctly.
    * Added a script to print build environment info for diagnostic use in test
      scripts, which is also now called by all.sh.
    * Added the macro MBEDTLS_X509_MAX_FILE_PATH_LEN that enables the user to
      configure the maximum length of a file path that can be buffered when
      calling mbedtls_x509_crt_parse_path().
    * Added a configuration file config-no-entropy.h that configures the subset of
      library features that do not require an entropy source.
    * Added the macro MBEDTLS_ENTROPY_MIN_HARDWARE in config.h. This allows users
      to configure the minimum number of bytes for entropy sources using the
      mbedtls_hardware_poll() function.
 
 Bugfix
    * Fix for platform time abstraction to avoid dependency issues where a build
      may need time but not the standard C library abstraction, and added
      configuration consistency checks to check_config.h
    * Fix dependency issue in Makefile to allow parallel builds.
    * Fix incorrect handling of block lengths in crypt_and_hash.c sample program,
      when GCM is used. Found by udf2457. #441
    * Fix for key exchanges based on ECDH-RSA or ECDH-ECDSA which weren't
      enabled unless others were also present. Found by David Fernandez. #428
    * Fix for out-of-tree builds using CMake. Found by jwurzer, and fix based on
      a contribution from Tobias Tangemann. #541
    * Fixed cert_app.c sample program for debug output and for use when no root
      certificates are provided.
    * Fix conditional statement that would cause a 1 byte overread in
      mbedtls_asn1_get_int(). Found and fixed by Guido Vranken. #599
    * Fixed pthread implementation to avoid unintended double initialisations
      and double frees. Found by Niklas Amnebratt.
    * Fixed the sample applications gen_key.c, cert_req.c and cert_write.c for
      builds where the configuration MBEDTLS_PEM_WRITE_C is not defined. Found
      by inestlerode. #559.
    * Fix mbedtls_x509_get_sig() to update the ASN1 type in the mbedtls_x509_buf
      data structure until after error checks are successful. Found by
      subramanyam-c. #622
    * Fix documentation and implementation missmatch for function arguments of
      mbedtls_gcm_finish(). Found by cmiatpaar. #602
    * Guarantee that P>Q at RSA key generation. Found by inestlerode. #558
    * Fix potential byte overread when verifying malformed SERVER_HELLO in
      ssl_parse_hello_verify_request() for DTLS. Found by Guido Vranken.
    * Fix check for validity of date when parsing in mbedtls_x509_get_time().
      Found by subramanyam-c. #626
    * Fix compatibility issue with Internet Explorer client authentication,
      where the limited hash choices prevented the client from sending its
      certificate. Found by teumas. #513
    * Fix compilation without MBEDTLS_SELF_TEST enabled.
 
 Changes
    * Extended test coverage of special cases, and added new timing test suite.
    * Removed self-tests from the basic-built-test.sh script, and added all
      missing self-tests to the test suites, to ensure self-tests are only
      executed once.
    * Added support for 3 and 4 byte lengths to mbedtls_asn1_write_len().
    * Added support for a Yotta specific configuration file -
      through the symbol YOTTA_CFG_MBEDTLS_TARGET_CONFIG_FILE.
    * Added optimization for code space for X.509/OID based on configured
      features. Contributed by Aviv Palivoda.
    * Renamed source file library/net.c to library/net_sockets.c to avoid
      naming collision in projects which also have files with the common name
      net.c. For consistency, the corresponding header file, net.h, is marked as
      deprecated, and its contents moved to net_sockets.h.
    * Changed the strategy for X.509 certificate parsing and validation, to no
      longer disregard certificates with unrecognised fields.
 
 = mbed TLS 2.3.0 branch released 2016-06-28
 
 Security
    * Fix missing padding length check in mbedtls_rsa_rsaes_pkcs1_v15_decrypt
      required by PKCS1 v2.2
    * Fix potential integer overflow to buffer overflow in
      mbedtls_rsa_rsaes_pkcs1_v15_encrypt and mbedtls_rsa_rsaes_oaep_encrypt
      (not triggerable remotely in (D)TLS).
    * Fix a potential integer underflow to buffer overread in
      mbedtls_rsa_rsaes_oaep_decrypt. It is not triggerable remotely in
      SSL/TLS.
 
 Features
    * Support for platform abstraction of the standard C library time()
      function.
 
 Bugfix
    * Fix bug in mbedtls_mpi_add_mpi() that caused wrong results when the three
      arguments where the same (in-place doubling). Found and fixed by Janos
      Follath. #309
    * Fix potential build failures related to the 'apidoc' target, introduced
      in the previous patch release. Found by Robert Scheck. #390 #391
    * Fix issue in Makefile that prevented building using armar. #386
    * Fix memory leak that occurred only when ECJPAKE was enabled and ECDHE and
      ECDSA was disabled in config.h . The leak didn't occur by default.
    * Fix an issue that caused valid certificates to be rejected whenever an
      expired or not yet valid certificate was parsed before a valid certificate
      in the trusted certificate list.
    * Fix bug in mbedtls_x509_crt_parse that caused trailing extra data in the
      buffer after DER certificates to be included in the raw representation.
    * Fix issue that caused a hang when generating RSA keys of odd bitlength
    * Fix bug in mbedtls_rsa_rsaes_pkcs1_v15_encrypt that made null pointer
      dereference possible.
    * Fix issue that caused a crash if invalid curves were passed to
      mbedtls_ssl_conf_curves. #373
    * Fix issue in ssl_fork_server which was preventing it from functioning. #429
    * Fix memory leaks in test framework
    * Fix test in ssl-opt.sh that does not run properly with valgrind
    * Fix unchecked calls to mmbedtls_md_setup(). Fix by Brian Murray. #502
 
 Changes
    * On ARM platforms, when compiling with -O0 with GCC, Clang or armcc5,
      don't use the optimized assembly for bignum multiplication. This removes
      the need to pass -fomit-frame-pointer to avoid a build error with -O0.
    * Disabled SSLv3 in the default configuration.
    * Optimized mbedtls_mpi_zeroize() for MPI integer size. (Fix by Alexey
      Skalozub).
    * Fix non-compliance server extension handling. Extensions for SSLv3 are now
      ignored, as required by RFC6101.
 
 = mbed TLS 2.2.1 released 2016-01-05
 
 Security
    * Fix potential double free when mbedtls_asn1_store_named_data() fails to
      allocate memory. Only used for certificate generation, not triggerable
      remotely in SSL/TLS. Found by Rafał Przywara. #367
    * Disable MD5 handshake signatures in TLS 1.2 by default to prevent the
      SLOTH attack on TLS 1.2 server authentication (other attacks from the
      SLOTH paper do not apply to any version of mbed TLS or PolarSSL).
      https://www.mitls.org/pages/attacks/SLOTH
 
 Bugfix
    * Fix over-restrictive length limit in GCM. Found by Andreas-N. #362
    * Fix bug in certificate validation that caused valid chains to be rejected
      when the first intermediate certificate has pathLenConstraint=0. Found by
      Nicholas Wilson. Introduced in mbed TLS 2.2.0. #280
    * Removed potential leak in mbedtls_rsa_rsassa_pkcs1_v15_sign(), found by
      JayaraghavendranK. #372
    * Fix suboptimal handling of unexpected records that caused interop issues
      with some peers over unreliable links. Avoid dropping an entire DTLS
      datagram if a single record in a datagram is unexpected, instead only
      drop the record and look at subsequent records (if any are present) in
      the same datagram. Found by jeannotlapin. #345
 
 = mbed TLS 2.2.0 released 2015-11-04
 
 Security
    * Fix potential double free if mbedtls_ssl_conf_psk() is called more than
      once and some allocation fails. Cannot be forced remotely. Found by Guido
      Vranken, Intelworks.
    * Fix potential heap corruption on Windows when
      mbedtls_x509_crt_parse_path() is passed a path longer than 2GB. Cannot be
      triggered remotely. Found by Guido Vranken, Intelworks.
    * Fix potential buffer overflow in some asn1_write_xxx() functions.
      Cannot be triggered remotely unless you create X.509 certificates based
      on untrusted input or write keys of untrusted origin. Found by Guido
      Vranken, Intelworks.
    * The X509 max_pathlen constraint was not enforced on intermediate
      certificates. Found by Nicholas Wilson, fix and tests provided by
      Janos Follath. #280 and #319
 
 Features
    * Experimental support for EC J-PAKE as defined in Thread 1.0.0.
      Disabled by default as the specification might still change.
    * Added a key extraction callback to accees the master secret and key
      block. (Potential uses include EAP-TLS and Thread.)
 
 Bugfix
    * Self-signed certificates were not excluded from pathlen counting,
      resulting in some valid X.509 being incorrectly rejected. Found and fix
      provided by Janos Follath. #319
    * Fix build error with configurations where ECDHE-PSK is the only key
      exchange. Found and fix provided by Chris Hammond. #270
    * Fix build error with configurations where RSA, RSA-PSK, ECDH-RSA or
      ECHD-ECDSA if the only key exchange. Multiple reports. #310
    * Fixed a bug causing some handshakes to fail due to some non-fatal alerts
      not being properly ignored. Found by mancha and Kasom Koht-arsa, #308
    * mbedtls_x509_crt_verify(_with_profile)() now also checks the key type and
      size/curve against the profile. Before that, there was no way to set a
      minimum key size for end-entity certificates with RSA keys. Found by
      Matthew Page of Scannex Electronics Ltd.
    * Fix failures in MPI on Sparc(64) due to use of bad assembly code.
      Found by Kurt Danielson. #292
    * Fix typo in name of the extKeyUsage OID. Found by inestlerode, #314
    * Fix bug in ASN.1 encoding of booleans that caused generated CA
      certificates to be rejected by some applications, including OS X
      Keychain. Found and fixed by Jonathan Leroy, Inikup.
 
 Changes
    * Improved performance of mbedtls_ecp_muladd() when one of the scalars is 1
      or -1.
 
 = mbed TLS 2.1.2 released 2015-10-06
 
 Security
    * Added fix for CVE-2015-5291 to prevent heap corruption due to buffer
      overflow of the hostname or session ticket. Found by Guido Vranken,
      Intelworks.
    * Fix potential double-free if mbedtls_ssl_set_hs_psk() is called more than
      once in the same handhake and mbedtls_ssl_conf_psk() was used.
      Found and patch provided by Guido Vranken, Intelworks. Cannot be forced
      remotely.
    * Fix stack buffer overflow in pkcs12 decryption (used by
      mbedtls_pk_parse_key(file)() when the password is > 129 bytes.
      Found by Guido Vranken, Intelworks. Not triggerable remotely.
    * Fix potential buffer overflow in mbedtls_mpi_read_string().
      Found by Guido Vranken, Intelworks. Not exploitable remotely in the context
      of TLS, but might be in other uses. On 32 bit machines, requires reading a
      string of close to or larger than 1GB to exploit; on 64 bit machines, would
      require reading a string of close to or larger than 2^62 bytes.
    * Fix potential random memory allocation in mbedtls_pem_read_buffer()
      on crafted PEM input data. Found and fix provided by Guido Vranken,
      Intelworks. Not triggerable remotely in TLS. Triggerable remotely if you
      accept PEM data from an untrusted source.
    * Fix possible heap buffer overflow in base64_encoded() when the input
      buffer is 512MB or larger on 32-bit platforms. Found by Guido Vranken,
      Intelworks. Not trigerrable remotely in TLS.
    * Fix potential double-free if mbedtls_conf_psk() is called repeatedly on
      the same mbedtls_ssl_config object and memory allocation fails. Found by
      Guido Vranken, Intelworks. Cannot be forced remotely.
    * Fix potential heap buffer overflow in servers that perform client
      authentication against a crafted CA cert. Cannot be triggered remotely
      unless you allow third parties to pick trust CAs for client auth.
      Found by Guido Vranken, Intelworks.
 
 Bugfix
    * Fix compile error in net.c with musl libc. Found and patch provided by
      zhasha (#278).
    * Fix macroization of 'inline' keyword when building as C++. (#279)
 
 Changes
    * Added checking of hostname length in mbedtls_ssl_set_hostname() to ensure
      domain names are compliant with RFC 1035.
    * Fixed paths for check_config.h in example config files. (Found by bachp)
      (#291)
 
 = mbed TLS 2.1.1 released 2015-09-17
 
 Security
    * Add countermeasure against Lenstra's RSA-CRT attack for PKCS#1 v1.5
      signatures. (Found by Florian Weimer, Red Hat.)
      https://securityblog.redhat.com/2015/09/02/factoring-rsa-keys-with-tls-perfect-forward-secrecy/
    * Fix possible client-side NULL pointer dereference (read) when the client
      tries to continue the handshake after it failed (a misuse of the API).
      (Found and patch provided by Fabian Foerg, Gotham Digital Science using
      afl-fuzz.)
 
 Bugfix
    * Fix warning when using a 64bit platform. (found by embedthis) (#275)
    * Fix off-by-one error in parsing Supported Point Format extension that
      caused some handshakes to fail.
 
 Changes
    * Made X509 profile pointer const in mbedtls_ssl_conf_cert_profile() to allow
      use of mbedtls_x509_crt_profile_next. (found by NWilson)
    * When a client initiates a reconnect from the same port as a live
      connection, if cookie verification is available
      (MBEDTLS_SSL_DTLS_HELLO_VERIFY defined in config.h, and usable cookie
      callbacks set with mbedtls_ssl_conf_dtls_cookies()), this will be
      detected and mbedtls_ssl_read() will return
      MBEDTLS_ERR_SSL_CLIENT_RECONNECT - it is then possible to start a new
      handshake with the same context. (See RFC 6347 section 4.2.8.)
 
 = mbed TLS 2.1.0 released 2015-09-04
 
 Features
    * Added support for yotta as a build system.
    * Primary open source license changed to Apache 2.0 license.
 
 Bugfix
    * Fix segfault in the benchmark program when benchmarking DHM.
    * Fix build error with CMake and pre-4.5 versions of GCC (found by Hugo
      Leisink).
    * Fix bug when parsing a ServerHello without extensions (found by David
      Sears).
    * Fix bug in CMake lists that caused libmbedcrypto.a not to be installed
      (found by Benoit Lecocq).
    * Fix bug in Makefile that caused libmbedcrypto and libmbedx509 not to be
      installed (found by Rawi666).
    * Fix compile error with armcc 5 with --gnu option.
    * Fix bug in Makefile that caused programs not to be installed correctly
      (found by robotanarchy) (#232).
    * Fix bug in Makefile that prevented from installing without building the
      tests (found by robotanarchy) (#232).
    * Fix missing -static-libgcc when building shared libraries for Windows
      with make.
    * Fix link error when building shared libraries for Windows with make.
    * Fix error when loading libmbedtls.so.
    * Fix bug in mbedtls_ssl_conf_default() that caused the default preset to
      be always used (found by dcb314) (#235)
    * Fix bug in mbedtls_rsa_public() and mbedtls_rsa_private() that could
      result trying to unlock an unlocked mutex on invalid input (found by
      Fredrik Axelsson) (#257)
    * Fix -Wshadow warnings (found by hnrkp) (#240)
    * Fix memory corruption on client with overlong PSK identity, around
      SSL_MAX_CONTENT_LEN or higher - not triggerrable remotely (found by
      Aleksandrs Saveljevs) (#238)
    * Fix unused function warning when using MBEDTLS_MDx_ALT or
      MBEDTLS_SHAxxx_ALT (found by Henrik) (#239)
    * Fix memory corruption in pkey programs (found by yankuncheng) (#210)
 
 Changes
    * The PEM parser now accepts a trailing space at end of lines (#226).
    * It is now possible to #include a user-provided configuration file at the
      end of the default config.h by defining MBEDTLS_USER_CONFIG_FILE on the
      compiler's command line.
    * When verifying a certificate chain, if an intermediate certificate is
      trusted, no later cert is checked. (suggested by hannes-landeholm)
      (#220).
    * Prepend a "thread identifier" to debug messages (issue pointed out by
      Hugo Leisink) (#210).
    * Add mbedtls_ssl_get_max_frag_len() to query the current maximum fragment
      length.
 
 = mbed TLS 2.0.0 released 2015-07-13
 
 Features
    * Support for DTLS 1.0 and 1.2 (RFC 6347).
    * Ability to override core functions from MDx, SHAx, AES and DES modules
      with custom implementation (eg hardware accelerated), complementing the
      ability to override the whole module.
    * New server-side implementation of session tickets that rotate keys to
      preserve forward secrecy, and allows sharing across multiple contexts.
    * Added a concept of X.509 cerificate verification profile that controls
      which algorithms and key sizes (curves for ECDSA) are acceptable.
    * Expanded configurability of security parameters in the SSL module with
      mbedtls_ssl_conf_dhm_min_bitlen() and mbedtls_ssl_conf_sig_hashes().
    * Introduced a concept of presets for SSL security-relevant configuration
      parameters.
 
 API Changes
    * The library has been split into libmbedcrypto, libmbedx509, libmbedtls.
      You now need to link to all of them if you use TLS for example.
    * All public identifiers moved to the mbedtls_* or MBEDTLS_* namespace.
      Some names have been further changed to make them more consistent.
      Migration helpers scripts/rename.pl and include/mbedtls/compat-1.3.h are
      provided. Full list of renamings in scripts/data_files/rename-1.3-2.0.txt
    * Renamings of fields inside structures, not covered by the previous list:
      mbedtls_cipher_info_t.key_length -> key_bitlen
      mbedtls_cipher_context_t.key_length -> key_bitlen
      mbedtls_ecp_curve_info.size -> bit_size
    * Headers are now found in the 'mbedtls' directory (previously 'polarssl').
    * The following _init() functions that could return errors have
      been split into an _init() that returns void and another function that
      should generally be the first function called on this context after init:
      mbedtls_ssl_init() -> mbedtls_ssl_setup()
      mbedtls_ccm_init() -> mbedtls_ccm_setkey()
      mbedtls_gcm_init() -> mbedtls_gcm_setkey()
      mbedtls_hmac_drbg_init() -> mbedtls_hmac_drbg_seed(_buf)()
      mbedtls_ctr_drbg_init()  -> mbedtls_ctr_drbg_seed()
      Note that for mbedtls_ssl_setup(), you need to be done setting up the
      ssl_config structure before calling it.
    * Most ssl_set_xxx() functions (all except ssl_set_bio(), ssl_set_hostname(),
      ssl_set_session() and ssl_set_client_transport_id(), plus
      ssl_legacy_renegotiation()) have been renamed to mbedtls_ssl_conf_xxx()
      (see rename.pl and compat-1.3.h above) and their first argument's type
      changed from ssl_context to ssl_config.
    * ssl_set_bio() changed signature (contexts merged, order switched, one
      additional callback for read-with-timeout).
    * The following functions have been introduced and must be used in callback
      implementations (SNI, PSK) instead of their *conf counterparts:
      mbedtls_ssl_set_hs_own_cert()
      mbedtls_ssl_set_hs_ca_chain()
      mbedtls_ssl_set_hs_psk()
    * mbedtls_ssl_conf_ca_chain() lost its last argument (peer_cn), now set
      using mbedtls_ssl_set_hostname().
    * mbedtls_ssl_conf_session_cache() changed prototype (only one context
      pointer, parameters reordered).
    * On server, mbedtls_ssl_conf_session_tickets_cb() must now be used in
      place of mbedtls_ssl_conf_session_tickets() to enable session tickets.
    * The SSL debug callback gained two new arguments (file name, line number).
    * Debug modes were removed.
    * mbedtls_ssl_conf_truncated_hmac() now returns void.
    * mbedtls_memory_buffer_alloc_init() now returns void.
    * X.509 verification flags are now an uint32_t. Affect the signature of:
      mbedtls_ssl_get_verify_result()
      mbedtls_x509_ctr_verify_info()
      mbedtls_x509_crt_verify() (flags, f_vrfy -> needs to be updated)
      mbedtls_ssl_conf_verify() (f_vrfy -> needs to be updated)
    * The following functions changed prototype to avoid an in-out length
      parameter:
      mbedtls_base64_encode()
      mbedtls_base64_decode()
      mbedtls_mpi_write_string()
      mbedtls_dhm_calc_secret()
    * In the NET module, all "int" and "int *" arguments for file descriptors
      changed type to "mbedtls_net_context *".
    * net_accept() gained new arguments for the size of the client_ip buffer.
    * In the threading layer, mbedtls_mutex_init() and mbedtls_mutex_free() now
      return void.
    * ecdsa_write_signature() gained an additional md_alg argument and
      ecdsa_write_signature_det() was deprecated.
    * pk_sign() no longer accepts md_alg == POLARSSL_MD_NONE with ECDSA.
    * Last argument of x509_crt_check_key_usage() and
      mbedtls_x509write_crt_set_key_usage() changed from int to unsigned.
    * test_ca_list (from certs.h) is renamed to test_cas_pem and is only
      available if POLARSSL_PEM_PARSE_C is defined (it never worked without).
    * Test certificates in certs.c are no longer guaranteed to be nul-terminated
      strings; use the new *_len variables instead of strlen().
    * Functions mbedtls_x509_xxx_parse(), mbedtls_pk_parse_key(),
      mbedtls_pk_parse_public_key() and mbedtls_dhm_parse_dhm() now expect the
      length parameter to include the terminating null byte for PEM input.
    * Signature of mpi_mul_mpi() changed to make the last argument unsigned
    * calloc() is now used instead of malloc() everywhere. API of platform
      layer and the memory_buffer_alloc module changed accordingly.
      (Thanks to Mansour Moufid for helping with the replacement.)
    * Change SSL_DISABLE_RENEGOTIATION config.h flag to SSL_RENEGOTIATION
      (support for renegotiation now needs explicit enabling in config.h).
    * Split MBEDTLS_HAVE_TIME into MBEDTLS_HAVE_TIME and MBEDTLS_HAVE_TIME_DATE
      in config.h
    * net_connect() and net_bind() have a new 'proto' argument to choose
      between TCP and UDP, using the macros NET_PROTO_TCP or NET_PROTO_UDP.
      Their 'port' argument type is changed to a string.
    * Some constness fixes
 
 Removals
    * Removed mbedtls_ecp_group_read_string(). Only named groups are supported.
    * Removed mbedtls_ecp_sub() and mbedtls_ecp_add(), use
      mbedtls_ecp_muladd().
    * Removed individual mdX_hmac, shaX_hmac, mdX_file and shaX_file functions
      (use generic functions from md.h)
    * Removed mbedtls_timing_msleep(). Use mbedtls_net_usleep() or a custom
      waiting function.
    * Removed test DHM parameters from the test certs module.
    * Removed the PBKDF2 module (use PKCS5).
    * Removed POLARSSL_ERROR_STRERROR_BC (use mbedtls_strerror()).
    * Removed compat-1.2.h (helper for migrating from 1.2 to 1.3).
    * Removed openssl.h (very partial OpenSSL compatibility layer).
    * Configuration options POLARSSL_HAVE_LONGLONG was removed (now always on).
    * Configuration options POLARSSL_HAVE_INT8 and POLARSSL_HAVE_INT16 have
      been removed (compiler is required to support 32-bit operations).
    * Configuration option POLARSSL_HAVE_IPV6 was removed (always enabled).
    * Removed test program o_p_test, the script compat.sh does more.
    * Removed test program ssl_test, superseded by ssl-opt.sh.
    * Removed helper script active-config.pl
 
 New deprecations
    * md_init_ctx() is deprecated in favour of md_setup(), that adds a third
      argument (allowing memory savings if HMAC is not used)
 
 Semi-API changes (technically public, morally private)
    * Renamed a few headers to include _internal in the name. Those headers are
      not supposed to be included by users.
    * Changed md_info_t into an opaque structure (use md_get_xxx() accessors).
    * Changed pk_info_t into an opaque structure.
    * Changed cipher_base_t into an opaque structure.
    * Removed sig_oid2 and rename sig_oid1 to sig_oid in x509_crt and x509_crl.
    * x509_crt.key_usage changed from unsigned char to unsigned int.
    * Removed r and s from ecdsa_context
    * Removed mode from des_context and des3_context
 
 Default behavior changes
    * The default minimum TLS version is now TLS 1.0.
    * RC4 is now blacklisted by default in the SSL/TLS layer, and excluded from the
      default ciphersuite list returned by ssl_list_ciphersuites()
    * Support for receiving SSLv2 ClientHello is now disabled by default at
      compile time.
    * The default authmode for SSL/TLS clients is now REQUIRED.
    * Support for RSA_ALT contexts in the PK layer is now optional. Since is is
      enabled in the default configuration, this is only noticeable if using a
      custom config.h
    * Default DHM parameters server-side upgraded from 1024 to 2048 bits.
    * A minimum RSA key size of 2048 bits is now enforced during ceritificate
      chain verification.
    * Negotiation of truncated HMAC is now disabled by default on server too.
    * The following functions are now case-sensitive:
      mbedtls_cipher_info_from_string()
      mbedtls_ecp_curve_info_from_name()
      mbedtls_md_info_from_string()
      mbedtls_ssl_ciphersuite_from_string()
      mbedtls_version_check_feature()
 
 Requirement changes
    * The minimum MSVC version required is now 2010 (better C99 support).
    * The NET layer now unconditionnaly relies on getaddrinfo() and select().
    * Compiler is required to support C99 types such as long long and uint32_t.
 
 API changes from the 1.4 preview branch
    * ssl_set_bio_timeout() was removed, split into mbedtls_ssl_set_bio() with
      new prototype, and mbedtls_ssl_set_read_timeout().
    * The following functions now return void:
      mbedtls_ssl_conf_transport()
      mbedtls_ssl_conf_max_version()
      mbedtls_ssl_conf_min_version()
    * DTLS no longer hard-depends on TIMING_C, but uses a callback interface
      instead, see mbedtls_ssl_set_timer_cb(), with the Timing module providing
      an example implementation, see mbedtls_timing_delay_context and
      mbedtls_timing_set/get_delay().
    * With UDP sockets, it is no longer necessary to call net_bind() again
      after a successful net_accept().
 
 Changes
    * mbedtls_ctr_drbg_random() and mbedtls_hmac_drbg_random() are now
      thread-safe if MBEDTLS_THREADING_C is enabled.
    * Reduced ROM fooprint of SHA-256 and added an option to reduce it even
      more (at the expense of performance) MBEDTLS_SHA256_SMALLER.
 
 = mbed TLS 1.3 branch
 
 Security
    * With authmode set to SSL_VERIFY_OPTIONAL, verification of keyUsage and
      extendedKeyUsage on the leaf certificate was lost (results not accessible
      via ssl_get_verify_results()).
    * Add countermeasure against "Lucky 13 strikes back" cache-based attack,
      https://dl.acm.org/citation.cfm?id=2714625
 
 Features
    * Improve ECC performance by using more efficient doubling formulas
      (contributed by Peter Dettman).
    * Add x509_crt_verify_info() to display certificate verification results.
    * Add support for reading DH parameters with privateValueLength included
      (contributed by Daniel Kahn Gillmor).
    * Add support for bit strings in X.509 names (request by Fredrik Axelsson).
    * Add support for id-at-uniqueIdentifier in X.509 names.
    * Add support for overriding snprintf() (except on Windows) and exit() in
      the platform layer.
    * Add an option to use macros instead of function pointers in the platform
      layer (helps get rid of unwanted references).
    * Improved Makefiles for Windows targets by fixing library targets and making
      cross-compilation easier (thanks to Alon Bar-Lev).
    * The benchmark program also prints heap usage for public-key primitives
      if POLARSSL_MEMORY_BUFFER_ALLOC_C and POLARSSL_MEMORY_DEBUG are defined.
    * New script ecc-heap.sh helps measuring the impact of ECC parameters on
      speed and RAM (heap only for now) usage.
    * New script memory.sh helps measuring the ROM and RAM requirements of two
      reduced configurations (PSK-CCM and NSA suite B).
    * Add config flag POLARSSL_DEPRECATED_WARNING (off by default) to produce
      warnings on use of deprecated functions (with GCC and Clang only).
    * Add config flag POLARSSL_DEPRECATED_REMOVED (off by default) to produce
      errors on use of deprecated functions.
 
 Bugfix
    * Fix compile errors with PLATFORM_NO_STD_FUNCTIONS.
    * Fix compile error with PLATFORM_EXIT_ALT (thanks to Rafał Przywara).
    * Fix bug in entropy.c when THREADING_C is also enabled that caused
      entropy_free() to crash (thanks to Rafał Przywara).
    * Fix memory leak when gcm_setkey() and ccm_setkey() are used more than
      once on the same context.
    * Fix bug in ssl_mail_client when password is longer that username (found
      by Bruno Pape).
    * Fix undefined behaviour (memcmp( NULL, NULL, 0 );) in X.509 modules
      (detected by Clang's 3.6 UBSan).
    * mpi_size() and mpi_msb() would segfault when called on an mpi that is
      initialized but not set (found by pravic).
    * Fix detection of support for getrandom() on Linux (reported by syzzer) by
      doing it at runtime (using uname) rather that compile time.
    * Fix handling of symlinks by "make install" (found by Gaël PORTAY).
    * Fix potential NULL pointer dereference (not trigerrable remotely) when
      ssl_write() is called before the handshake is finished (introduced in
      1.3.10) (first reported by Martin Blumenstingl).
    * Fix bug in pk_parse_key() that caused some valid private EC keys to be
      rejected.
    * Fix bug in Via Padlock support (found by Nikos Mavrogiannopoulos).
    * Fix thread safety bug in RSA operations (found by Fredrik Axelsson).
    * Fix hardclock() (only used in the benchmarking program) with some
      versions of mingw64 (found by kxjhlele).
    * Fix warnings from mingw64 in timing.c (found by kxjklele).
    * Fix potential unintended sign extension in asn1_get_len() on 64-bit
      platforms.
    * Fix potential memory leak in ssl_set_psk() (found by Mansour Moufid).
    * Fix compile error when POLARSSL_SSL_DISABLE_RENEGOTATION and
      POLARSSL_SSL_SSESSION_TICKETS where both enabled in config.h (introduced
      in 1.3.10).
    * Add missing extern "C" guard in aesni.h (reported by amir zamani).
    * Add missing dependency on SHA-256 in some x509 programs (reported by
      Gergely Budai).
    * Fix bug related to ssl_set_curves(): the client didn't check that the
      curve picked by the server was actually allowed.
 
 Changes
    * Remove bias in mpi_gen_prime (contributed by Pascal Junod).
    * Remove potential sources of timing variations (some contributed by Pascal
      Junod).
    * Options POLARSSL_HAVE_INT8 and POLARSSL_HAVE_INT16 are deprecated.
    * Enabling POLARSSL_NET_C without POLARSSL_HAVE_IPV6 is deprecated.
    * compat-1.2.h and openssl.h are deprecated.
    * Adjusting/overriding CFLAGS and LDFLAGS with the make build system is now
      more flexible (warning: OFLAGS is not used any more) (see the README)
      (contributed by Alon Bar-Lev).
    * ssl_set_own_cert() no longer calls pk_check_pair() since the
      performance impact was bad for some users (this was introduced in 1.3.10).
    * Move from SHA-1 to SHA-256 in example programs using signatures
      (suggested by Thorsten Mühlfelder).
    * Remove some unneeded inclusions of header files from the standard library
      "minimize" others (eg use stddef.h if only size_t is needed).
    * Change #include lines in test files to use double quotes instead of angle
      brackets for uniformity with the rest of the code.
    * Remove dependency on sscanf() in X.509 parsing modules.
 
 = mbed TLS 1.3.10 released 2015-02-09
 Security
    * NULL pointer dereference in the buffer-based allocator when the buffer is
      full and polarssl_free() is called (found by Mark Hasemeyer)
      (only possible if POLARSSL_MEMORY_BUFFER_ALLOC_C is enabled, which it is
      not by default).
    * Fix remotely-triggerable uninitialised pointer dereference caused by
      crafted X.509 certificate (TLS server is not affected if it doesn't ask for a
      client certificate) (found using Codenomicon Defensics).
    * Fix remotely-triggerable memory leak caused by crafted X.509 certificates
      (TLS server is not affected if it doesn't ask for a client certificate)
      (found using Codenomicon Defensics).
    * Fix potential stack overflow while parsing crafted X.509 certificates
      (TLS server is not affected if it doesn't ask for a client certificate)
      (found using Codenomicon Defensics).
    * Fix timing difference that could theoretically lead to a
      Bleichenbacher-style attack in the RSA and RSA-PSK key exchanges
      (reported by Sebastian Schinzel).
 
 Features
    * Add support for FALLBACK_SCSV (draft-ietf-tls-downgrade-scsv).
    * Add support for Extended Master Secret (draft-ietf-tls-session-hash).
    * Add support for Encrypt-then-MAC (RFC 7366).
    * Add function pk_check_pair() to test if public and private keys match.
    * Add x509_crl_parse_der().
    * Add compile-time option POLARSSL_X509_MAX_INTERMEDIATE_CA to limit the
      length of an X.509 verification chain.
    * Support for renegotiation can now be disabled at compile-time
    * Support for 1/n-1 record splitting, a countermeasure against BEAST.
    * Certificate selection based on signature hash, preferring SHA-1 over SHA-2
      for pre-1.2 clients when multiple certificates are available.
    * Add support for getrandom() syscall on recent Linux kernels with Glibc or
      a compatible enough libc (eg uClibc).
    * Add ssl_set_arc4_support() to make it easier to disable RC4 at runtime
      while using the default ciphersuite list.
    * Added new error codes and debug messages about selection of
      ciphersuite/certificate.
 
 Bugfix
    * Stack buffer overflow if ctr_drbg_update() is called with too large
      add_len (found by Jean-Philippe Aumasson) (not triggerable remotely).
    * Possible buffer overflow of length at most POLARSSL_MEMORY_ALIGN_MULTIPLE
      if memory_buffer_alloc_init() was called with buf not aligned and len not
      a multiple of POLARSSL_MEMORY_ALIGN_MULTIPLE (not triggerable remotely).
    * User set CFLAGS were ignored by Cmake with gcc (introduced in 1.3.9, found
      by Julian Ospald).
    * Fix potential undefined behaviour in Camellia.
    * Fix potential failure in ECDSA signatures when POLARSSL_ECP_MAX_BITS is a
      multiple of 8 (found by Gergely Budai).
    * Fix unchecked return code in x509_crt_parse_path() on Windows (found by
      Peter Vaskovic).
    * Fix assembly selection for MIPS64 (thanks to James Cowgill).
    * ssl_get_verify_result() now works even if the handshake was aborted due
      to a failed verification (found by Fredrik Axelsson).
    * Skip writing and parsing signature_algorithm extension if none of the
      key exchanges enabled needs certificates. This fixes a possible interop
      issue with some servers when a zero-length extension was sent. (Reported
      by Peter Dettman.)
    * On a 0-length input, base64_encode() did not correctly set output length
      (found by Hendrik van den Boogaard).
 
 Changes
    * Use deterministic nonces for AEAD ciphers in TLS by default (possible to
      switch back to random with POLARSSL_SSL_AEAD_RANDOM_IV in config.h).
    * Blind RSA private operations even when POLARSSL_RSA_NO_CRT is defined.
    * ssl_set_own_cert() now returns an error on key-certificate mismatch.
    * Forbid repeated extensions in X.509 certificates.
    * debug_print_buf() now prints a text view in addition to hexadecimal.
    * A specific error is now returned when there are ciphersuites in common
      but none of them is usable due to external factors such as no certificate
      with a suitable (extended)KeyUsage or curve or no PSK set.
    * It is now possible to disable negotiation of truncated HMAC server-side
      at runtime with ssl_set_truncated_hmac().
    * Example programs for SSL client and server now disable SSLv3 by default.
    * Example programs for SSL client and server now disable RC4 by default.
    * Use platform.h in all test suites and programs.
 
 = PolarSSL 1.3.9 released 2014-10-20
 Security
    * Lowest common hash was selected from signature_algorithms extension in
      TLS 1.2 (found by Darren Bane) (introduced in 1.3.8).
    * Remotely-triggerable memory leak when parsing some X.509 certificates
      (server is not affected if it doesn't ask for a client certificate)
      (found using Codenomicon Defensics).
    * Remotely-triggerable memory leak when parsing crafted ClientHello
      (not affected if ECC support was compiled out) (found using Codenomicon
      Defensics).
 
 Bugfix
    * Support escaping of commas in x509_string_to_names()
    * Fix compile error in ssl_pthread_server (found by Julian Ospald).
    * Fix net_accept() regarding non-blocking sockets (found by Luca Pesce).
    * Don't print uninitialised buffer in ssl_mail_client (found by Marc Abel).
    * Fix warnings from Clang's scan-build (contributed by Alfred Klomp).
    * Fix compile error in timing.c when POLARSSL_NET_C and POLARSSL_SELFTEST
      are defined but not POLARSSL_HAVE_TIME (found by Stephane Di Vito).
    * Remove non-existent file from VS projects (found by Peter Vaskovic).
    * ssl_read() could return non-application data records on server while
      renegotation was pending, and on client when a HelloRequest was received.
    * Server-initiated renegotiation would fail with non-blocking I/O if the
      write callback returned WANT_WRITE when requesting renegotiation.
    * ssl_close_notify() could send more than one message in some circumstances
      with non-blocking I/O.
    * Fix compiler warnings on iOS (found by Sander Niemeijer).
    * x509_crt_parse() did not increase total_failed on PEM error
    * Fix compile error with armcc in mpi_is_prime()
    * Fix potential bad read in parsing ServerHello (found by Adrien
      Vialletelle).
 
 Changes
    * Ciphersuites using SHA-256 or SHA-384 now require TLS 1.x (there is no
      standard defining how to use SHA-2 with SSL 3.0).
    * Ciphersuites using RSA-PSK key exchange new require TLS 1.x (the spec is
      ambiguous on how to encode some packets with SSL 3.0).
    * Made buffer size in pk_write_(pub)key_pem() more dynamic, eg smaller if
      RSA is disabled, larger if POLARSSL_MPI_MAX_SIZE is larger.
    * ssl_read() now returns POLARSSL_ERR_NET_WANT_READ rather than
      POLARSSL_ERR_SSL_UNEXPECTED_MESSAGE on harmless alerts.
    * POLARSSL_MPI_MAX_SIZE now defaults to 1024 in order to allow 8192 bits
      RSA keys.
    * Accept spaces at end of line or end of buffer in base64_decode().
    * X.509 certificates with more than one AttributeTypeAndValue per
      RelativeDistinguishedName are not accepted any more.
 
 = PolarSSL 1.3.8 released 2014-07-11
 Security
    * Fix length checking for AEAD ciphersuites (found by Codenomicon).
      It was possible to crash the server (and client) using crafted messages
      when a GCM suite was chosen.
 
 Features
    * Add CCM module and cipher mode to Cipher Layer
    * Support for CCM and CCM_8 ciphersuites
    * Support for parsing and verifying RSASSA-PSS signatures in the X.509
      modules (certificates, CRLs and CSRs).
    * Blowfish in the cipher layer now supports variable length keys.
    * Add example config.h for PSK with CCM, optimized for low RAM usage.
    * Optimize for RAM usage in example config.h for NSA Suite B profile.
    * Add POLARSSL_REMOVE_ARC4_CIPHERSUITES to allow removing RC4 ciphersuites
      from the default list (inactive by default).
    * Add server-side enforcement of sent renegotiation requests
      (ssl_set_renegotiation_enforced())
    * Add SSL_CIPHERSUITES config.h flag to allow specifying a list of
      ciphersuites to use and save some memory if the list is small.
 
 Changes
    * Add LINK_WITH_PTHREAD option in CMake for explicit linking that is
      required on some platforms (e.g. OpenBSD)
    * Migrate zeroizing of data to polarssl_zeroize() instead of memset()
      against unwanted compiler optimizations
    * md_list() now returns hashes strongest first
    * Selection of hash for signing ServerKeyExchange in TLS 1.2 now picks
      strongest offered by client.
    * All public contexts have _init() and _free() functions now for simpler
      usage pattern
 
 Bugfix
    * Fix in debug_print_msg()
    * Enforce alignment in the buffer allocator even if buffer is not aligned
    * Remove less-than-zero checks on unsigned numbers
    * Stricter check on SSL ClientHello internal sizes compared to actual packet
      size (found by TrustInSoft)
    * Fix WSAStartup() return value check (found by Peter Vaskovic)
    * Other minor issues (found by Peter Vaskovic)
    * Fix symlink command for cross compiling with CMake (found by Andre
      Heinecke)
    * Fix DER output of gen_key app (found by Gergely Budai)
    * Very small records were incorrectly rejected when truncated HMAC was in
      use with some ciphersuites and versions (RC4 in all versions, CBC with
      versions < TLS 1.1).
    * Very large records using more than 224 bytes of padding were incorrectly
      rejected with CBC-based ciphersuites and TLS >= 1.1
    * Very large records using less padding could cause a buffer overread of up
      to 32 bytes with CBC-based ciphersuites and TLS >= 1.1
    * Restore ability to use a v1 cert as a CA if trusted locally. (This had
      been removed in 1.3.6.)
    * Restore ability to locally trust a self-signed cert that is not a proper
      CA for use as an end entity certificate. (This had been removed in
      1.3.6.)
    * Fix preprocessor checks for bn_mul PPC asm (found by Barry K. Nathan).
    * Use \n\t rather than semicolons for bn_mul asm, since some assemblers
      interpret semicolons as comment delimiters (found by Barry K. Nathan).
    * Fix off-by-one error in parsing Supported Point Format extension that
      caused some handshakes to fail.
    * Fix possible miscomputation of the premaster secret with DHE-PSK key
      exchange that caused some handshakes to fail with other implementations.
      (Failure rate <= 1/255 with common DHM moduli.)
    * Disable broken Sparc64 bn_mul assembly (found by Florian Obser).
    * Fix base64_decode() to return and check length correctly (in case of
      tight buffers)
    * Fix mpi_write_string() to write "00" as hex output for empty MPI (found
      by Hui Dong)
 
 = PolarSSL 1.3.7 released on 2014-05-02
 Features
    * debug_set_log_mode() added to determine raw or full logging
    * debug_set_threshold() added to ignore messages over threshold level
    * version_check_feature() added to check for compile-time options at
      run-time
 
 Changes
    * POLARSSL_CONFIG_OPTIONS has been removed. All values are individually
      checked and filled in the relevant module headers
    * Debug module only outputs full lines instead of parts
    * Better support for the different Attribute Types from IETF PKIX (RFC 5280)
    * AES-NI now compiles with "old" assemblers too
    * Ciphersuites based on RC4 now have the lowest priority by default
 
 Bugfix
    * Only iterate over actual certificates in ssl_write_certificate_request()
      (found by Matthew Page)
    * Typos in platform.c and pkcs11.c (found by Daniel Phillips and Steffan
      Karger)
    * cert_write app should use subject of issuer certificate as issuer of cert
    * Fix false reject in padding check in ssl_decrypt_buf() for CBC
      ciphersuites, for full SSL frames of data.
    * Improve interoperability by not writing extension length in ClientHello /
      ServerHello when no extensions are present (found by Matthew Page)
    * rsa_check_pubkey() now allows an E up to N
    * On OpenBSD, use arc4random_buf() instead of rand() to prevent warnings
    * mpi_fill_random() was creating numbers larger than requested on
      big-endian platform when size was not an integer number of limbs
    * Fix dependencies issues in X.509 test suite.
    * Some parts of ssl_tls.c were compiled even when the module was disabled.
    * Fix detection of DragonflyBSD in net.c (found by Markus Pfeiffer)
    * Fix detection of Clang on some Apple platforms with CMake
      (found by Barry K. Nathan)
 
 = PolarSSL 1.3.6 released on 2014-04-11
 
 Features
    * Support for the ALPN SSL extension
    * Add option 'use_dev_random' to gen_key application
    * Enable verification of the keyUsage extension for CA and leaf
      certificates (POLARSSL_X509_CHECK_KEY_USAGE)
    * Enable verification of the extendedKeyUsage extension
      (POLARSSL_X509_CHECK_EXTENDED_KEY_USAGE)
 
 Changes
    * x509_crt_info() now prints information about parsed extensions as well
    * pk_verify() now returns a specific error code when the signature is valid
      but shorter than the supplied length.
    * Use UTC time to check certificate validity.
    * Reject certificates with times not in UTC, per RFC 5280.
 
 Security
    * Avoid potential timing leak in ecdsa_sign() by blinding modular division.
      (Found by Watson Ladd.)
    * The notAfter date of some certificates was no longer checked since 1.3.5.
      This affects certificates in the user-supplied chain except the top
      certificate. If the user-supplied chain contains only one certificates,
      it is not affected (ie, its notAfter date is properly checked).
    * Prevent potential NULL pointer dereference in ssl_read_record() (found by
      TrustInSoft)
 
 Bugfix
    * The length of various ClientKeyExchange messages was not properly checked.
    * Some example server programs were not sending the close_notify alert.
    * Potential memory leak in mpi_exp_mod() when error occurs during
      calculation of RR.
    * Fixed malloc/free default #define in platform.c (found by Gergely Budai).
    * Fixed type which made POLARSSL_ENTROPY_FORCE_SHA256 uneffective (found by
      Gergely Budai).
    * Fix #include path in ecdsa.h which wasn't accepted by some compilers.
      (found by Gergely Budai)
    * Fix compile errors when POLARSSL_ERROR_STRERROR_BC is undefined (found by
      Shuo Chen).
    * oid_get_numeric_string() used to truncate the output without returning an
      error if the output buffer was just 1 byte too small.
    * dhm_parse_dhm() (hence dhm_parse_dhmfile()) did not set dhm->len.
    * Calling pk_debug() on an RSA-alt key would segfault.
    * pk_get_size() and pk_get_len() were off by a factor 8 for RSA-alt keys.
    * Potential buffer overwrite in pem_write_buffer() because of low length
      indication (found by Thijs Alkemade)
    * EC curves constants, which should be only in ROM since 1.3.3, were also
      stored in RAM due to missing 'const's (found by Gergely Budai).
 
 = PolarSSL 1.3.5 released on 2014-03-26
 Features
    * HMAC-DRBG as a separate module
    * Option to set the Curve preference order (disabled by default)
    * Single Platform compatilibity layer (for memory / printf / fprintf)
    * Ability to provide alternate timing implementation
    * Ability to force the entropy module to use SHA-256 as its basis
      (POLARSSL_ENTROPY_FORCE_SHA256)
    * Testing script ssl-opt.sh added for testing 'live' ssl option
      interoperability against OpenSSL and PolarSSL
    * Support for reading EC keys that use SpecifiedECDomain in some cases.
    * Entropy module now supports seed writing and reading
 
 Changes
    * Deprecated the Memory layer
    * entropy_add_source(), entropy_update_manual() and entropy_gather()
      now thread-safe if POLARSSL_THREADING_C defined
    * Improvements to the CMake build system, contributed by Julian Ospald.
    * Work around a bug of the version of Clang shipped by Apple with Mavericks
      that prevented bignum.c from compiling. (Reported by Rafael Baptista.)
    * Revamped the compat.sh interoperatibility script to include support for
      testing against GnuTLS
    * Deprecated ssl_set_own_cert_rsa() and ssl_set_own_cert_rsa_alt()
    * Improvements to tests/Makefile, contributed by Oden Eriksson.
 
 Security
    * Forbid change of server certificate during renegotiation to prevent
      "triple handshake" attack when authentication mode is 'optional' (the
      attack was already impossible when authentication is required).
    * Check notBefore timestamp of certificates and CRLs from the future.
    * Forbid sequence number wrapping
    * Fixed possible buffer overflow with overlong PSK
    * Possible remotely-triggered out-of-bounds memory access fixed (found by
      TrustInSoft)
 
 Bugfix
    * ecp_gen_keypair() does more tries to prevent failure because of
      statistics
    * Fixed bug in RSA PKCS#1 v1.5 "reversed" operations
    * Fixed testing with out-of-source builds using cmake
    * Fixed version-major intolerance in server
    * Fixed CMake symlinking on out-of-source builds
    * Fixed dependency issues in test suite
    * Programs rsa_sign_pss and rsa_verify_pss were not using PSS since 1.3.0
    * Bignum's MIPS-32 assembly was used on MIPS-64, causing chaos. (Found by
      Alex Wilson.)
    * ssl_cache was creating entries when max_entries=0 if TIMING_C was enabled.
    * m_sleep() was sleeping twice too long on most Unix platforms.
    * Fixed bug with session tickets and non-blocking I/O in the unlikely case
      send() would return an EAGAIN error when sending the ticket.
    * ssl_cache was leaking memory when reusing a timed out entry containing a
      client certificate.
    * ssl_srv was leaking memory when client presented a timed out ticket
      containing a client certificate
    * ssl_init() was leaving a dirty pointer in ssl_context if malloc of
      out_ctr failed
    * ssl_handshake_init() was leaving dirty pointers in subcontexts if malloc
      of one of them failed
    * Fix typo in rsa_copy() that impacted PKCS#1 v2 contexts
    * x509_get_current_time() uses localtime_r() to prevent thread issues
 
 = PolarSSL 1.3.4 released on 2014-01-27
 Features
    * Support for the Koblitz curves: secp192k1, secp224k1, secp256k1
    * Support for RIPEMD-160
    * Support for AES CFB8 mode
    * Support for deterministic ECDSA (RFC 6979)
 
 Bugfix
    * Potential memory leak in bignum_selftest()
    * Replaced expired test certificate
    * ssl_mail_client now terminates lines with CRLF, instead of LF
    * net module handles timeouts on blocking sockets better (found by Tilman
      Sauerbeck)
    * Assembly format fixes in bn_mul.h
 
 Security
    * Missing MPI_CHK calls added around unguarded mpi calls (found by
      TrustInSoft)
 
 = PolarSSL 1.3.3 released on 2013-12-31
 Features
    * EC key generation support in gen_key app
    * Support for adhering to client ciphersuite order preference
      (POLARSSL_SSL_SRV_RESPECT_CLIENT_PREFERENCE)
    * Support for Curve25519
    * Support for ECDH-RSA and ECDH-ECDSA key exchanges and ciphersuites
    * Support for IPv6 in the NET module
    * AES-NI support for AES, AES-GCM and AES key scheduling
    * SSL Pthread-based server example added (ssl_pthread_server)
 
 Changes
    * gen_prime() speedup
    * Speedup of ECP multiplication operation
    * Relaxed some SHA2 ciphersuite's version requirements
    * Dropped use of readdir_r() instead of readdir() with threading support
    * More constant-time checks in the RSA module
    * Split off curves from ecp.c into ecp_curves.c
    * Curves are now stored fully in ROM
    * Memory usage optimizations in ECP module
    * Removed POLARSSL_THREADING_DUMMY
 
 Bugfix
    * Fixed bug in mpi_set_bit() on platforms where t_uint is wider than int
    * Fixed X.509 hostname comparison (with non-regular characters)
    * SSL now gracefully handles missing RNG
    * Missing defines / cases for RSA_PSK key exchange
    * crypt_and_hash app checks MAC before final decryption
    * Potential memory leak in ssl_ticket_keys_init()
    * Memory leak in benchmark application
    * Fixed x509_crt_parse_path() bug on Windows platforms
    * Added missing MPI_CHK() around some statements in mpi_div_mpi() (found by
      TrustInSoft)
    * Fixed potential overflow in certificate size verification in
      ssl_write_certificate() (found by TrustInSoft)
 
 Security
    * Possible remotely-triggered out-of-bounds memory access fixed (found by
      TrustInSoft)
 
 = PolarSSL 1.3.2 released on 2013-11-04
 Features
    * PK tests added to test framework
    * Added optional optimization for NIST MODP curves (POLARSSL_ECP_NIST_OPTIM)
    * Support for Camellia-GCM mode and ciphersuites
 
 Changes
    * Padding checks in cipher layer are now constant-time
    * Value comparisons in SSL layer are now constant-time
    * Support for serialNumber, postalAddress and postalCode in X509 names
    * SSL Renegotiation was refactored
 
 Bugfix
    * More stringent checks in cipher layer
    * Server does not send out extensions not advertised by client
    * Prevent possible alignment warnings on casting from char * to 'aligned *'
    * Misc fixes and additions to dependency checks
    * Const correctness
    * cert_write with selfsign should use issuer_name as subject_name
    * Fix ECDSA corner case: missing reduction mod N (found by DualTachyon)
    * Defines to handle UEFI environment under MSVC
    * Server-side initiated renegotiations send HelloRequest
 
 = PolarSSL 1.3.1 released on 2013-10-15
 Features
    * Support for Brainpool curves and TLS ciphersuites (RFC 7027)
    * Support for ECDHE-PSK key-exchange and ciphersuites
    * Support for RSA-PSK key-exchange and ciphersuites
 
 Changes
    * RSA blinding locks for a smaller amount of time
    * TLS compression only allocates working buffer once
    * Introduced POLARSSL_HAVE_READDIR_R for systems without it
    * config.h is more script-friendly
 
 Bugfix
    * Missing MSVC defines added
    * Compile errors with POLARSSL_RSA_NO_CRT
    * Header files with 'polarssl/'
    * Const correctness
    * Possible naming collision in dhm_context
    * Better support for MSVC
    * threading_set_alt() name
    * Added missing x509write_crt_set_version()
 
 = PolarSSL 1.3.0 released on 2013-10-01
 Features
    * Elliptic Curve Cryptography module added
    * Elliptic Curve Diffie Hellman module added
    * Ephemeral Elliptic Curve Diffie Hellman support for SSL/TLS
     (ECDHE-based ciphersuites)
    * Ephemeral Elliptic Curve Digital Signature Algorithm support for SSL/TLS
     (ECDSA-based ciphersuites)
    * Ability to specify allowed ciphersuites based on the protocol version.
    * PSK and DHE-PSK based ciphersuites added
    * Memory allocation abstraction layer added
    * Buffer-based memory allocator added (no malloc() / free() / HEAP usage)
    * Threading abstraction layer added (dummy / pthread / alternate)
    * Public Key abstraction layer added
    * Parsing Elliptic Curve keys
    * Parsing Elliptic Curve certificates
    * Support for max_fragment_length extension (RFC 6066)
    * Support for truncated_hmac extension (RFC 6066)
    * Support for zeros-and-length (ANSI X.923) padding, one-and-zeros
      (ISO/IEC 7816-4) padding and zero padding in the cipher layer
    * Support for session tickets (RFC 5077)
    * Certificate Request (CSR) generation with extensions (key_usage,
      ns_cert_type)
    * X509 Certificate writing with extensions (basic_constraints,
      issuer_key_identifier, etc)
    * Optional blinding for RSA, DHM and EC
    * Support for multiple active certificate / key pairs in SSL servers for
      the same host (Not to be confused with SNI!)
 
 Changes
    * Ability to enable / disable SSL v3 / TLS 1.0 / TLS 1.1 / TLS 1.2
      individually
    * Introduced separate SSL Ciphersuites module that is based on
      Cipher and MD information
    * Internals for SSL module adapted to have separate IV pointer that is
      dynamically set (Better support for hardware acceleration)
    * Moved all OID functionality to a separate module. RSA function
      prototypes for the RSA sign and verify functions changed as a result
    * Split up the GCM module into a starts/update/finish cycle
    * Client and server now filter sent and accepted ciphersuites on minimum
      and maximum protocol version
    * Ability to disable server_name extension (RFC 6066)
    * Renamed error_strerror() to the less conflicting polarssl_strerror()
      (Ability to keep old as well with POLARSSL_ERROR_STRERROR_BC)
    * SHA2 renamed to SHA256, SHA4 renamed to SHA512 and functions accordingly
    * All RSA operations require a random generator for blinding purposes
    * X509 core refactored
    * x509_crt_verify() now case insensitive for cn (RFC 6125 6.4)
    * Also compiles / runs without time-based functions (!POLARSSL_HAVE_TIME)
    * Support faulty X509 v1 certificates with extensions
      (POLARSSL_X509_ALLOW_EXTENSIONS_NON_V3)
 
 Bugfix
    * Fixed parse error in ssl_parse_certificate_request()
    * zlib compression/decompression skipped on empty blocks
    * Support for AIX header locations in net.c module
    * Fixed file descriptor leaks
 
 Security
    * RSA blinding on CRT operations to counter timing attacks
      (found by Cyril Arnaud and Pierre-Alain Fouque)
 
 
 = Version 1.2.14 released 2015-05-??
 
 Security
    * Fix potential invalid memory read in the server, that allows a client to
      crash it remotely (found by Caj Larsson).
    * Fix potential invalid memory read in certificate parsing, that allows a
      client to crash the server remotely if client authentication is enabled
      (found using Codenomicon Defensics).
    * Add countermeasure against "Lucky 13 strikes back" cache-based attack,
      https://dl.acm.org/citation.cfm?id=2714625
 
 Bugfix
    * Fix bug in Via Padlock support (found by Nikos Mavrogiannopoulos).
    * Fix hardclock() (only used in the benchmarking program) with some
      versions of mingw64 (found by kxjhlele).
    * Fix warnings from mingw64 in timing.c (found by kxjklele).
    * Fix potential unintended sign extension in asn1_get_len() on 64-bit
      platforms (found with Coverity Scan).
 
 = Version 1.2.13 released 2015-02-16
 Note: Although PolarSSL has been renamed to mbed TLS, no changes reflecting
       this will be made in the 1.2 branch at this point.
 
 Security
    * Fix remotely-triggerable uninitialised pointer dereference caused by
      crafted X.509 certificate (TLS server is not affected if it doesn't ask
      for a client certificate) (found using Codenomicon Defensics).
    * Fix remotely-triggerable memory leak caused by crafted X.509 certificates
      (TLS server is not affected if it doesn't ask for a client certificate)
      (found using Codenomicon Defensics).
    * Fix potential stack overflow while parsing crafted X.509 certificates
      (TLS server is not affected if it doesn't ask for a client certificate)
      found using Codenomicon Defensics).
    * Fix buffer overread of size 1 when parsing crafted X.509 certificates
      (TLS server is not affected if it doesn't ask for a client certificate).
 
 Bugfix
    * Fix potential undefined behaviour in Camellia.
    * Fix memory leaks in PKCS#5 and PKCS#12.
    * Stack buffer overflow if ctr_drbg_update() is called with too large
      add_len (found by Jean-Philippe Aumasson) (not triggerable remotely).
    * Fix bug in MPI/bignum on s390/s390x (reported by Dan Horák) (introduced
      in 1.2.12).
    * Fix unchecked return code in x509_crt_parse_path() on Windows (found by
      Peter Vaskovic).
    * Fix assembly selection for MIPS64 (thanks to James Cowgill).
    * ssl_get_verify_result() now works even if the handshake was aborted due
      to a failed verification (found by Fredrik Axelsson).
    * Skip writing and parsing signature_algorithm extension if none of the
      key exchanges enabled needs certificates. This fixes a possible interop
      issue with some servers when a zero-length extension was sent. (Reported
      by Peter Dettman.)
    * On a 0-length input, base64_encode() did not correctly set output length
      (found by Hendrik van den Boogaard).
 
 Changes
    * Blind RSA private operations even when POLARSSL_RSA_NO_CRT is defined.
    * Forbid repeated extensions in X.509 certificates.
    * Add compile-time option POLARSSL_X509_MAX_INTERMEDIATE_CA to limit the
      length of an X.509 verification chain (default = 8).
 = Version 1.2.12 released 2014-10-24
 
 Security
    * Remotely-triggerable memory leak when parsing some X.509 certificates
      (server is not affected if it doesn't ask for a client certificate).
      (Found using Codenomicon Defensics.)
 
 Bugfix
    * Fix potential bad read in parsing ServerHello (found by Adrien
      Vialletelle).
    * ssl_close_notify() could send more than one message in some circumstances
      with non-blocking I/O.
    * x509_crt_parse() did not increase total_failed on PEM error
    * Fix compiler warnings on iOS (found by Sander Niemeijer).
    * Don't print uninitialised buffer in ssl_mail_client (found by Marc Abel).
    * Fix net_accept() regarding non-blocking sockets (found by Luca Pesce).
    * ssl_read() could return non-application data records on server while
      renegotation was pending, and on client when a HelloRequest was received.
    * Fix warnings from Clang's scan-build (contributed by Alfred Klomp).
 
 Changes
    * X.509 certificates with more than one AttributeTypeAndValue per
      RelativeDistinguishedName are not accepted any more.
    * ssl_read() now returns POLARSSL_ERR_NET_WANT_READ rather than
      POLARSSL_ERR_SSL_UNEXPECTED_MESSAGE on harmless alerts.
    * Accept spaces at end of line or end of buffer in base64_decode().
 
 = Version 1.2.11 released 2014-07-11
 Features
    * Entropy module now supports seed writing and reading
 
 Changes
    * Introduced POLARSSL_HAVE_READDIR_R for systems without it
    * Improvements to the CMake build system, contributed by Julian Ospald.
    * Work around a bug of the version of Clang shipped by Apple with Mavericks
      that prevented bignum.c from compiling. (Reported by Rafael Baptista.)
    * Improvements to tests/Makefile, contributed by Oden Eriksson.
    * Use UTC time to check certificate validity.
    * Reject certificates with times not in UTC, per RFC 5280.
    * Migrate zeroizing of data to polarssl_zeroize() instead of memset()
      against unwanted compiler optimizations
 
 Security
    * Forbid change of server certificate during renegotiation to prevent
      "triple handshake" attack when authentication mode is optional (the
      attack was already impossible when authentication is required).
    * Check notBefore timestamp of certificates and CRLs from the future.
    * Forbid sequence number wrapping
    * Prevent potential NULL pointer dereference in ssl_read_record() (found by
      TrustInSoft)
    * Fix length checking for AEAD ciphersuites (found by Codenomicon).
      It was possible to crash the server (and client) using crafted messages
      when a GCM suite was chosen.
 
 Bugfix
    * Fixed X.509 hostname comparison (with non-regular characters)
    * SSL now gracefully handles missing RNG
    * crypt_and_hash app checks MAC before final decryption
    * Fixed x509_crt_parse_path() bug on Windows platforms
    * Added missing MPI_CHK() around some statements in mpi_div_mpi() (found by
      TrustInSoft)
    * Fixed potential overflow in certificate size verification in
      ssl_write_certificate() (found by TrustInSoft)
    * Fix ASM format in bn_mul.h
    * Potential memory leak in bignum_selftest()
    * Replaced expired test certificate
    * ssl_mail_client now terminates lines with CRLF, instead of LF
    * Fix bug in RSA PKCS#1 v1.5 "reversed" operations
    * Fixed testing with out-of-source builds using cmake
    * Fixed version-major intolerance in server
    * Fixed CMake symlinking on out-of-source builds
    * Bignum's MIPS-32 assembly was used on MIPS-64, causing chaos. (Found by
      Alex Wilson.)
    * ssl_init() was leaving a dirty pointer in ssl_context if malloc of
      out_ctr failed
    * ssl_handshake_init() was leaving dirty pointers in subcontexts if malloc
      of one of them failed
    * x509_get_current_time() uses localtime_r() to prevent thread issues
    * Some example server programs were not sending the close_notify alert.
    * Potential memory leak in mpi_exp_mod() when error occurs during
      calculation of RR.
    * Improve interoperability by not writing extension length in ClientHello
      when no extensions are present (found by Matthew Page)
    * rsa_check_pubkey() now allows an E up to N
    * On OpenBSD, use arc4random_buf() instead of rand() to prevent warnings
    * mpi_fill_random() was creating numbers larger than requested on
      big-endian platform when size was not an integer number of limbs
    * Fix detection of DragonflyBSD in net.c (found by Markus Pfeiffer)
    * Stricter check on SSL ClientHello internal sizes compared to actual packet
      size (found by TrustInSoft)
    * Fix preprocessor checks for bn_mul PPC asm (found by Barry K. Nathan).
    * Use \n\t rather than semicolons for bn_mul asm, since some assemblers
      interpret semicolons as comment delimiters (found by Barry K. Nathan).
    * Disable broken Sparc64 bn_mul assembly (found by Florian Obser).
    * Fix base64_decode() to return and check length correctly (in case of
      tight buffers)
 
 = Version 1.2.10 released 2013-10-07
 Changes
    * Changed RSA blinding to a slower but thread-safe version
 
 Bugfix
    * Fixed memory leak in RSA as a result of introduction of blinding
    * Fixed ssl_pkcs11_decrypt() prototype
    * Fixed MSVC project files
 
 = Version 1.2.9 released 2013-10-01
 Changes
    * x509_verify() now case insensitive for cn (RFC 6125 6.4)
 
 Bugfix
    * Fixed potential memory leak when failing to resume a session
    * Fixed potential file descriptor leaks (found by Remi Gacogne)
    * Minor fixes
 
 Security
    * Fixed potential heap buffer overflow on large hostname setting
    * Fixed potential negative value misinterpretation in load_file()
    * RSA blinding on CRT operations to counter timing attacks
      (found by Cyril Arnaud and Pierre-Alain Fouque)
 
 = Version 1.2.8 released 2013-06-19
 Features
    * Parsing of PKCS#8 encrypted private key files
    * PKCS#12 PBE and derivation functions
    * Centralized module option values in config.h to allow user-defined
      settings without editing header files by using POLARSSL_CONFIG_OPTIONS
 
 Changes
    * HAVEGE random generator disabled by default
    * Internally split up x509parse_key() into a (PEM) handler function
      and specific DER parser functions for the PKCS#1 and unencrypted
      PKCS#8 private key formats
    * Added mechanism to provide alternative implementations for all
      symmetric cipher and hash algorithms (e.g. POLARSSL_AES_ALT in
      config.h)
    * PKCS#5 module added. Moved PBKDF2 functionality inside and deprecated
      old PBKDF2 module
 
 Bugfix
    * Secure renegotiation extension should only be sent in case client
      supports secure renegotiation
    * Fixed offset for cert_type list in ssl_parse_certificate_request()
    * Fixed const correctness issues that have no impact on the ABI
    * x509parse_crt() now better handles PEM error situations
    * ssl_parse_certificate() now calls x509parse_crt_der() directly
      instead of the x509parse_crt() wrapper that can also parse PEM
      certificates
    * x509parse_crtpath() is now reentrant and uses more portable stat()
    * Fixed bignum.c and bn_mul.h to support Thumb2 and LLVM compiler
    * Fixed values for 2-key Triple DES in cipher layer
    * ssl_write_certificate_request() can handle empty ca_chain
 
 Security
    * A possible DoS during the SSL Handshake, due to faulty parsing of
      PEM-encoded certificates has been fixed (found by Jack Lloyd)
 
 = Version 1.2.7 released 2013-04-13
 Features
    * Ability to specify allowed ciphersuites based on the protocol version.
 
 Changes
    * Default Blowfish keysize is now 128-bits
    * Test suites made smaller to accommodate Raspberry Pi
 
 Bugfix
    * Fix for MPI assembly for ARM
    * GCM adapted to support sizes > 2^29
 
 = Version 1.2.6 released 2013-03-11
 Bugfix
    * Fixed memory leak in ssl_free() and ssl_reset() for active session
    * Corrected GCM counter incrementation to use only 32-bits instead of
      128-bits (found by Yawning Angel)
    * Fixes for 64-bit compilation with MS Visual Studio
    * Fixed net_bind() for specified IP addresses on little endian systems
    * Fixed assembly code for ARM (Thumb and regular) for some compilers
 
 Changes
    * Internally split up rsa_pkcs1_encrypt(), rsa_pkcs1_decrypt(),
      rsa_pkcs1_sign() and rsa_pkcs1_verify() to separate PKCS#1 v1.5 and
      PKCS#1 v2.1 functions
    * Added support for custom labels when using rsa_rsaes_oaep_encrypt()
      or rsa_rsaes_oaep_decrypt()
    * Re-added handling for SSLv2 Client Hello when the define
      POLARSSL_SSL_SRV_SUPPORT_SSLV2_CLIENT_HELLO is set
    * The SSL session cache module (ssl_cache) now also retains peer_cert
      information (not the entire chain)
 
 Security
    * Removed further timing differences during SSL message decryption in
      ssl_decrypt_buf()
    * Removed timing differences due to bad padding from
      rsa_rsaes_pkcs1_v15_decrypt() and rsa_pkcs1_decrypt() for PKCS#1 v1.5
      operations
 
 = Version 1.2.5 released 2013-02-02
 Changes
    * Allow enabling of dummy error_strerror() to support some use-cases
    * Debug messages about padding errors during SSL message decryption are
      disabled by default and can be enabled with POLARSSL_SSL_DEBUG_ALL
    * Sending of security-relevant alert messages that do not break
      interoperability can be switched on/off with the flag
      POLARSSL_SSL_ALL_ALERT_MESSAGES
 
 Security
    * Removed timing differences during SSL message decryption in
      ssl_decrypt_buf() due to badly formatted padding
 
 = Version 1.2.4 released 2013-01-25
 Changes
    * More advanced SSL ciphersuite representation and moved to more dynamic
      SSL core
    * Added ssl_handshake_step() to allow single stepping the handshake process
 
 Bugfix
    * Memory leak when using RSA_PKCS_V21 operations fixed
    * Handle future version properly in ssl_write_certificate_request()
    * Correctly handle CertificateRequest message in client for <= TLS 1.1
      without DN list
 
 = Version 1.2.3 released 2012-11-26
 Bugfix
    * Server not always sending correct CertificateRequest message
 
 = Version 1.2.2 released 2012-11-24
 Changes
    * Added p_hw_data to ssl_context for context specific hardware acceleration
      data
    * During verify trust-CA is only checked for expiration and CRL presence
 
 Bugfixes
    * Fixed client authentication compatibility
    * Fixed dependency on POLARSSL_SHA4_C in SSL modules
 
 = Version 1.2.1 released 2012-11-20
 Changes
    * Depth that the certificate verify callback receives is now numbered
      bottom-up (Peer cert depth is 0)
 
 Bugfixes
    * Fixes for MSVC6
    * Moved mpi_inv_mod() outside POLARSSL_GENPRIME
    * Allow R and A to point to same mpi in mpi_div_mpi (found by Manuel
      Pégourié-Gonnard)
    * Fixed possible segfault in mpi_shift_r() (found by Manuel
      Pégourié-Gonnard)
    * Added max length check for rsa_pkcs1_sign with PKCS#1 v2.1
 
 = Version 1.2.0 released 2012-10-31
 Features
    * Added support for NULL cipher (POLARSSL_CIPHER_NULL_CIPHER) and weak
      ciphersuites (POLARSSL_ENABLE_WEAK_CIPHERSUITES). They are disabled by
      default!
    * Added support for wildcard certificates
    * Added support for multi-domain certificates through the X509 Subject
      Alternative Name extension
    * Added preliminary ASN.1 buffer writing support
    * Added preliminary X509 Certificate Request writing support
    * Added key_app_writer example application
    * Added cert_req example application
    * Added base Galois Counter Mode (GCM) for AES
    * Added TLS 1.2 support (RFC 5246)
    * Added GCM suites to TLS 1.2 (RFC 5288)
    * Added commandline error code convertor (util/strerror)
    * Added support for Hardware Acceleration hooking in SSL/TLS
    * Added OpenSSL / PolarSSL compatibility script (tests/compat.sh) and
      example application (programs/ssl/o_p_test) (requires OpenSSL)
    * Added X509 CA Path support
    * Added Thumb assembly optimizations
    * Added DEFLATE compression support as per RFC3749 (requires zlib)
    * Added blowfish algorithm (Generic and cipher layer)
    * Added PKCS#5 PBKDF2 key derivation function
    * Added Secure Renegotiation (RFC 5746)
    * Added predefined DHM groups from RFC 5114
    * Added simple SSL session cache implementation
    * Added ServerName extension parsing (SNI) at server side
    * Added option to add minimum accepted SSL/TLS protocol version
 
 Changes
    * Removed redundant POLARSSL_DEBUG_MSG define
    * AES code only check for Padlock once
    * Fixed const-correctness mpi_get_bit()
    * Documentation for mpi_lsb() and mpi_msb()
    * Moved out_msg to out_hdr + 32 to support hardware acceleration
    * Changed certificate verify behaviour to comply with RFC 6125 section 6.3
      to not match CN if subjectAltName extension is present (Closes ticket #56)
    * Cipher layer cipher_mode_t POLARSSL_MODE_CFB128 is renamed to
      POLARSSL_MODE_CFB, to also handle different block size CFB modes.
    * Removed handling for SSLv2 Client Hello (as per RFC 5246 recommendation)
    * Revamped session resumption handling
    * Generalized external private key implementation handling (like PKCS#11)
      in SSL/TLS
    * Revamped x509_verify() and the SSL f_vrfy callback implementations
    * Moved from unsigned long to fixed width uint32_t types throughout code
    * Renamed ciphersuites naming scheme to IANA reserved names
 
 Bugfix
    * Fixed handling error in mpi_cmp_mpi() on longer B values (found by
      Hui Dong)
    * Fixed potential heap corruption in x509_name allocation
    * Fixed single RSA test that failed on Big Endian systems (Closes ticket #54)
    * mpi_exp_mod() now correctly handles negative base numbers (Closes ticket
      #52)
    * Handle encryption with private key and decryption with public key as per
      RFC 2313
    * Handle empty certificate subject names
    * Prevent reading over buffer boundaries on X509 certificate parsing
    * mpi_add_abs() now correctly handles adding short numbers to long numbers
      with carry rollover (found by Ruslan Yushchenko)
    * Handle existence of OpenSSL Trust Extensions at end of X.509 DER blob
    * Fixed MPI assembly for SPARC64 platform
 
 Security
    * Fixed potential memory zeroization on miscrafted RSA key (found by Eloi
      Vanderbeken)
 
 = Version 1.1.8 released on 2013-10-01
 Bugfix
    * Fixed potential memory leak when failing to resume a session
    * Fixed potential file descriptor leaks
 
 Security
    * Potential buffer-overflow for ssl_read_record() (independently found by
      both TrustInSoft and Paul Brodeur of Leviathan Security Group)
    * Potential negative value misinterpretation in load_file()
    * Potential heap buffer overflow on large hostname setting
 
 = Version 1.1.7 released on 2013-06-19
 Changes
    * HAVEGE random generator disabled by default
 
 Bugfix
    * x509parse_crt() now better handles PEM error situations
    * ssl_parse_certificate() now calls x509parse_crt_der() directly
      instead of the x509parse_crt() wrapper that can also parse PEM
      certificates
    * Fixed values for 2-key Triple DES in cipher layer
    * ssl_write_certificate_request() can handle empty ca_chain
 
 Security
    * A possible DoS during the SSL Handshake, due to faulty parsing of
      PEM-encoded certificates has been fixed (found by Jack Lloyd)
 
 = Version 1.1.6 released on 2013-03-11
 Bugfix
    * Fixed net_bind() for specified IP addresses on little endian systems
 
 Changes
    * Allow enabling of dummy error_strerror() to support some use-cases
    * Debug messages about padding errors during SSL message decryption are
      disabled by default and can be enabled with POLARSSL_SSL_DEBUG_ALL
 
 Security
    * Removed timing differences during SSL message decryption in
      ssl_decrypt_buf()
    * Removed timing differences due to bad padding from
      rsa_rsaes_pkcs1_v15_decrypt() and rsa_pkcs1_decrypt() for PKCS#1 v1.5
      operations
 
 = Version 1.1.5 released on 2013-01-16
 Bugfix
    * Fixed MPI assembly for SPARC64 platform
    * Handle existence of OpenSSL Trust Extensions at end of X.509 DER blob
    * mpi_add_abs() now correctly handles adding short numbers to long numbers
      with carry rollover
    * Moved mpi_inv_mod() outside POLARSSL_GENPRIME
    * Prevent reading over buffer boundaries on X509 certificate parsing
    * mpi_exp_mod() now correctly handles negative base numbers (Closes ticket
      #52)
    * Fixed possible segfault in mpi_shift_r() (found by Manuel
      Pégourié-Gonnard)
    * Allow R and A to point to same mpi in mpi_div_mpi (found by Manuel
      Pégourié-Gonnard)
    * Added max length check for rsa_pkcs1_sign with PKCS#1 v2.1
    * Memory leak when using RSA_PKCS_V21 operations fixed
    * Handle encryption with private key and decryption with public key as per
      RFC 2313
    * Fixes for MSVC6
 
 Security
    * Fixed potential memory zeroization on miscrafted RSA key (found by Eloi
      Vanderbeken)
 
 = Version 1.1.4 released on 2012-05-31
 Bugfix
    * Correctly handle empty SSL/TLS packets (Found by James Yonan)
    * Fixed potential heap corruption in x509_name allocation
    * Fixed single RSA test that failed on Big Endian systems (Closes ticket #54)
 
 = Version 1.1.3 released on 2012-04-29
 Bugfix
    * Fixed random MPI generation to not generate more size than requested.
 
 = Version 1.1.2 released on 2012-04-26
 Bugfix
    * Fixed handling error in mpi_cmp_mpi() on longer B values (found by
      Hui Dong)
 
 Security
    * Fixed potential memory corruption on miscrafted client messages (found by
      Frama-C team at CEA LIST)
    * Fixed generation of DHM parameters to correct length (found by Ruslan
      Yushchenko)
 
 = Version 1.1.1 released on 2012-01-23
 Bugfix
    * Check for failed malloc() in ssl_set_hostname() and x509_get_entries()
      (Closes ticket #47, found by Hugo Leisink)
    * Fixed issues with Intel compiler on 64-bit systems (Closes ticket #50)
    * Fixed multiple compiler warnings for VS6 and armcc
    * Fixed bug in CTR_CRBG selftest
 
 = Version 1.1.0 released on 2011-12-22
 Features
    * Added ssl_session_reset() to allow better multi-connection pools of
      SSL contexts without needing to set all non-connection-specific
      data and pointers again. Adapted ssl_server to use this functionality.
    * Added ssl_set_max_version() to allow clients to offer a lower maximum
      supported version to a server to help buggy server implementations.
      (Closes ticket #36)
    * Added cipher_get_cipher_mode() and cipher_get_cipher_operation()
      introspection functions (Closes ticket #40)
    * Added CTR_DRBG based on AES-256-CTR (NIST SP 800-90) random generator
    * Added a generic entropy accumulator that provides support for adding
      custom entropy sources and added some generic and platform dependent
      entropy sources
 
 Changes
    * Documentation for AES and Camellia in modes CTR and CFB128 clarified.
    * Fixed rsa_encrypt and rsa_decrypt examples to use public key for
      encryption and private key for decryption. (Closes ticket #34)
    * Inceased maximum size of ASN1 length reads to 32-bits.
    * Added an EXPLICIT tag number parameter to x509_get_ext()
    * Added a separate CRL entry extension parsing function
    * Separated the ASN.1 parsing code from the X.509 specific parsing code.
      So now there is a module that is controlled with POLARSSL_ASN1_PARSE_C.
    * Changed the defined key-length of DES ciphers in cipher.h to include the
      parity bits, to prevent mistakes in copying data. (Closes ticket #33)
    * Loads of minimal changes to better support WINCE as a build target
      (Credits go to Marco Lizza)
    * Added POLARSSL_MPI_WINDOW_SIZE definition to allow easier time to memory
      trade-off
    * Introduced POLARSSL_MPI_MAX_SIZE and POLARSSL_MPI_MAX_BITS for MPI size
      management (Closes ticket #44)
    * Changed the used random function pointer to more flexible format. Renamed
      havege_rand() to havege_random() to prevent mistakes. Lots of changes as
      a consequence in library code and programs
    * Moved all examples programs to use the new entropy and CTR_DRBG
    * Added permissive certificate parsing to x509parse_crt() and
      x509parse_crtfile(). With permissive parsing the parsing does not stop on
      encountering a parse-error. Beware that the meaning of return values has
      changed!
    * All error codes are now negative. Even on mermory failures and IO errors.
 
 Bugfix
    * Fixed faulty HMAC-MD2 implementation. Found by dibac. (Closes
      ticket #37)
    * Fixed a bug where the CRL parser expected an EXPLICIT ASN.1 tag
      before version numbers
    * Allowed X509 key usage parsing to accept 4 byte values instead of the
      standard 1 byte version sometimes used by Microsoft. (Closes ticket #38)
    * Fixed incorrect behaviour in case of RSASSA-PSS with a salt length
      smaller than the hash length. (Closes ticket #41)
    * If certificate serial is longer than 32 octets, serial number is now
      appended with '....' after first 28 octets
    * Improved build support for s390x and sparc64 in bignum.h
    * Fixed MS Visual C++ name clash with int64 in sha4.h
    * Corrected removal of leading "00:" in printing serial numbers in
      certificates and CRLs
 
 = Version 1.0.0 released on 2011-07-27
 Features
    * Expanded cipher layer with support for CFB128 and CTR mode
    * Added rsa_encrypt and rsa_decrypt simple example programs.
 
 Changes
    * The generic cipher and message digest layer now have normal error
      codes instead of integers
 
 Bugfix
    * Undid faulty bug fix in ssl_write() when flushing old data (Ticket
      #18)
 
 = Version 0.99-pre5 released on 2011-05-26
 Features
    * Added additional Cipher Block Modes to symmetric ciphers
      (AES CTR, Camellia CTR, XTEA CBC) including the option to
      enable and disable individual modes when needed
    * Functions requiring File System functions can now be disabled
      by undefining POLARSSL_FS_IO
    * A error_strerror function() has been added to translate between
      error codes and their description.
    * Added mpi_get_bit() and mpi_set_bit() individual bit setter/getter
      functions.
    * Added ssl_mail_client and ssl_fork_server as example programs.
 
 Changes
    * Major argument / variable rewrite. Introduced use of size_t
      instead of int for buffer lengths and loop variables for
      better unsigned / signed use. Renamed internal bigint types
      t_int and t_dbl to t_uint and t_udbl in the process
    * mpi_init() and mpi_free() now only accept a single MPI
      argument and do not accept variable argument lists anymore.
    * The error codes have been remapped and combining error codes
      is now done with a PLUS instead of an OR as error codes
      used are negative.
    * Changed behaviour of net_read(), ssl_fetch_input() and ssl_recv().
      net_recv() now returns 0 on EOF instead of
      POLARSSL_ERR_NET_CONN_RESET. ssl_fetch_input() returns
      POLARSSL_ERR_SSL_CONN_EOF on an EOF from its f_recv() function.
      ssl_read() returns 0 if a POLARSSL_ERR_SSL_CONN_EOF is received
      after the handshake.
    * Network functions now return POLARSSL_ERR_NET_WANT_READ or
      POLARSSL_ERR_NET_WANT_WRITE instead of the ambiguous
      POLARSSL_ERR_NET_TRY_AGAIN
 
 = Version 0.99-pre4 released on 2011-04-01
 Features
    * Added support for PKCS#1 v2.1 encoding and thus support
      for the RSAES-OAEP and RSASSA-PSS operations.
    * Reading of Public Key files incorporated into default x509
      functionality as well.
    * Added mpi_fill_random() for centralized filling of big numbers
      with random data (Fixed ticket #10)
 
 Changes
    * Debug print of MPI now removes leading zero octets and
      displays actual bit size of the value.
    * x509parse_key() (and as a consequence x509parse_keyfile())
      does not zeroize memory in advance anymore. Use rsa_init()
      before parsing a key or keyfile!
 
 Bugfix
    * Debug output of MPI's now the same independent of underlying
      platform (32-bit / 64-bit) (Fixes ticket #19, found by Mads
      Kiilerich and Mihai Militaru)
    * Fixed bug in ssl_write() when flushing old data (Fixed ticket
      #18, found by Nikolay Epifanov)
    * Fixed proper handling of RSASSA-PSS verification with variable
      length salt lengths
 
 = Version 0.99-pre3 released on 2011-02-28
 This release replaces version 0.99-pre2 which had possible copyright issues.
 Features
    * Parsing PEM private keys encrypted with DES and AES
      are now supported as well (Fixes ticket #5)
    * Added crl_app program to allow easy reading and
      printing of X509 CRLs from file
 
 Changes
    * Parsing of PEM files moved to separate module (Fixes
      ticket #13). Also possible to remove PEM support for
      systems only using DER encoding
 
 Bugfixes
    * Corrected parsing of UTCTime dates before 1990 and
      after 1950
    * Support more exotic OID's when parsing certificates
      (found by Mads Kiilerich)
    * Support more exotic name representations when parsing
      certificates (found by Mads Kiilerich)
    * Replaced the expired test certificates
    * Do not bail out if no client certificate specified. Try
      to negotiate anonymous connection (Fixes ticket #12,
      found by Boris Krasnovskiy)
 
 Security fixes
    * Fixed a possible Man-in-the-Middle attack on the
      Diffie Hellman key exchange (thanks to Larry Highsmith,
      Subreption LLC)
 
 = Version 0.99-pre1 released on 2011-01-30
 Features
 Note: Most of these features have been donated by Fox-IT
    * Added Doxygen source code documentation parts
    * Added reading of DHM context from memory and file
    * Improved X509 certificate parsing to include extended
      certificate fields, including Key Usage
    * Improved certificate verification and verification
      against the available CRLs
    * Detection for DES weak keys and parity bits added
    * Improvements to support integration in other
      applications:
        + Added generic message digest and cipher wrapper
        + Improved information about current capabilities,
          status, objects and configuration
        + Added verification callback on certificate chain
          verification to allow external blacklisting
        + Additional example programs to show usage
    * Added support for PKCS#11 through the use of the
      libpkcs11-helper library
 
 Changes
    * x509parse_time_expired() checks time in addition to
      the existing date check
    * The ciphers member of ssl_context and the cipher member
      of ssl_session have been renamed to ciphersuites and
      ciphersuite respectively. This clarifies the difference
      with the generic cipher layer and is better naming
      altogether
 
 = Version 0.14.0 released on 2010-08-16
 Features
    * Added support for SSL_EDH_RSA_AES_128_SHA and
      SSL_EDH_RSA_CAMELLIA_128_SHA ciphersuites
    * Added compile-time and run-time version information
    * Expanded ssl_client2 arguments for more flexibility
    * Added support for TLS v1.1
 
 Changes
    * Made Makefile cleaner
    * Removed dependency on rand() in rsa_pkcs1_encrypt().
      Now using random fuction provided to function and
      changed the prototype of rsa_pkcs1_encrypt(),
      rsa_init() and rsa_gen_key().
    * Some SSL defines were renamed in order to avoid
      future confusion
 
 Bug fixes
    * Fixed CMake out of source build for tests (found by
      kkert)
    * rsa_check_private() now supports PKCS1v2 keys as well
    * Fixed deadlock in rsa_pkcs1_encrypt() on failing random
      generator
 
 = Version 0.13.1 released on 2010-03-24
 Bug fixes
    * Fixed Makefile in library that was mistakenly merged
    * Added missing const string fixes
 
 = Version 0.13.0 released on 2010-03-21
 Features
    * Added option parsing for host and port selection to
      ssl_client2
    * Added support for GeneralizedTime in X509 parsing
    * Added cert_app program to allow easy reading and
      printing of X509 certificates from file or SSL
      connection.
 
 Changes
    * Added const correctness for main code base
    * X509 signature algorithm determination is now
      in a function to allow easy future expansion
    * Changed symmetric cipher functions to
      identical interface (returning int result values)
    * Changed ARC4 to use separate input/output buffer
    * Added reset function for HMAC context as speed-up
      for specific use-cases
 
 Bug fixes
    * Fixed bug resulting in failure to send the last
      certificate in the chain in ssl_write_certificate() and
      ssl_write_certificate_request() (found by fatbob)
    * Added small fixes for compiler warnings on a Mac
      (found by Frank de Brabander)
    * Fixed algorithmic bug in mpi_is_prime() (found by
      Smbat Tonoyan)
 
 = Version 0.12.1 released on 2009-10-04
 Changes
    * Coverage test definitions now support 'depends_on'
      tagging system.
    * Tests requiring specific hashing algorithms now honor
      the defines.
 
 Bug fixes
    * Changed typo in #ifdef in x509parse.c (found
      by Eduardo)
 
 = Version 0.12.0 released on 2009-07-28
 Features
    * Added CMake makefiles as alternative to regular Makefiles.
    * Added preliminary Code Coverage tests for AES, ARC4,
      Base64, MPI, SHA-family, MD-family, HMAC-SHA-family,
      Camellia, DES, 3-DES, RSA PKCS#1, XTEA, Diffie-Hellman
      and X509parse.
 
 Changes
    * Error codes are not (necessarily) negative. Keep
      this is mind when checking for errors.
    * RSA_RAW renamed to SIG_RSA_RAW for consistency.
    * Fixed typo in name of POLARSSL_ERR_RSA_OUTPUT_TOO_LARGE.
    * Changed interface for AES and Camellia setkey functions
      to indicate invalid key lengths.
 
 Bug fixes
    * Fixed include location of endian.h on FreeBSD (found by
      Gabriel)
    * Fixed include location of endian.h and name clash on
      Apples (found by Martin van Hensbergen)
    * Fixed HMAC-MD2 by modifying md2_starts(), so that the
      required HMAC ipad and opad variables are not cleared.
      (found by code coverage tests)
    * Prevented use of long long in bignum if
      POLARSSL_HAVE_LONGLONG not defined (found by Giles
      Bathgate).
    * Fixed incorrect handling of negative strings in
      mpi_read_string() (found by code coverage tests).
    * Fixed segfault on handling empty rsa_context in
      rsa_check_pubkey() and rsa_check_privkey() (found by
      code coverage tests).
    * Fixed incorrect handling of one single negative input
      value in mpi_add_abs() (found by code coverage tests).
    * Fixed incorrect handling of negative first input
      value in mpi_sub_abs() (found by code coverage tests).
    * Fixed incorrect handling of negative first input
      value in mpi_mod_mpi() and mpi_mod_int(). Resulting
      change also affects mpi_write_string() (found by code
      coverage tests).
    * Corrected is_prime() results for 0, 1 and 2 (found by
      code coverage tests).
    * Fixed Camellia and XTEA for 64-bit Windows systems.
 
 = Version 0.11.1 released on 2009-05-17
    * Fixed missing functionality for SHA-224, SHA-256, SHA384,
      SHA-512 in rsa_pkcs1_sign()
 
 = Version 0.11.0 released on 2009-05-03
    * Fixed a bug in mpi_gcd() so that it also works when both
      input numbers are even and added testcases to check
      (found by Pierre Habouzit).
    * Added support for SHA-224, SHA-256, SHA-384 and SHA-512
      one way hash functions with the PKCS#1 v1.5 signing and
      verification.
    * Fixed minor bug regarding mpi_gcd located within the
      POLARSSL_GENPRIME block.
    * Fixed minor memory leak in x509parse_crt() and added better
      handling of 'full' certificate chains (found by Mathias
      Olsson).
    * Centralized file opening and reading for x509 files into
      load_file()
    * Made definition of net_htons() endian-clean for big endian
      systems (Found by Gernot).
    * Undefining POLARSSL_HAVE_ASM now also handles prevents asm in
      padlock and timing code.
    * Fixed an off-by-one buffer allocation in ssl_set_hostname()
      responsible for crashes and unwanted behaviour.
    * Added support for Certificate Revocation List (CRL) parsing.
    * Added support for CRL revocation to x509parse_verify() and
      SSL/TLS code.
    * Fixed compatibility of XTEA and Camellia on a 64-bit system
      (found by Felix von Leitner).
 
 = Version 0.10.0 released on 2009-01-12
    * Migrated XySSL to PolarSSL
    * Added XTEA symmetric cipher
    * Added Camellia symmetric cipher
    * Added support for ciphersuites: SSL_RSA_CAMELLIA_128_SHA,
      SSL_RSA_CAMELLIA_256_SHA and SSL_EDH_RSA_CAMELLIA_256_SHA
    * Fixed dangerous bug that can cause a heap overflow in
      rsa_pkcs1_decrypt (found by Christophe Devine)
 
 ================================================================
 XySSL ChangeLog
 
 = Version 0.9 released on 2008-03-16
 
     * Added support for ciphersuite: SSL_RSA_AES_128_SHA
     * Enabled support for large files by default in aescrypt2.c
     * Preliminary openssl wrapper contributed by David Barrett
     * Fixed a bug in ssl_write() that caused the same payload to
       be sent twice in non-blocking mode when send returns EAGAIN
     * Fixed ssl_parse_client_hello(): session id and challenge must
       not be swapped in the SSLv2 ClientHello (found by Greg Robson)
     * Added user-defined callback debug function (Krystian Kolodziej)
     * Before freeing a certificate, properly zero out all cert. data
     * Fixed the "mode" parameter so that encryption/decryption are
       not swapped on PadLock; also fixed compilation on older versions
       of gcc (bug reported by David Barrett)
     * Correctly handle the case in padlock_xcryptcbc() when input or
       output data is non-aligned by falling back to the software
       implementation, as VIA Nehemiah cannot handle non-aligned buffers
     * Fixed a memory leak in x509parse_crt() which was reported by Greg
       Robson-Garth; some x509write.c fixes by Pascal Vizeli, thanks to
       Matthew Page who reported several bugs
     * Fixed x509_get_ext() to accept some rare certificates which have
       an INTEGER instead of a BOOLEAN for BasicConstraints::cA.
     * Added support on the client side for the TLS "hostname" extension
       (patch contributed by David Patino)
     * Make x509parse_verify() return BADCERT_CN_MISMATCH when an empty
       string is passed as the CN (bug reported by spoofy)
     * Added an option to enable/disable the BN assembly code
     * Updated rsa_check_privkey() to verify that (D*E) = 1 % (P-1)*(Q-1)
     * Disabled obsolete hash functions by default (MD2, MD4); updated
       selftest and benchmark to not test ciphers that have been disabled
     * Updated x509parse_cert_info() to correctly display byte 0 of the
       serial number, setup correct server port in the ssl client example
     * Fixed a critical denial-of-service with X.509 cert. verification:
       peer may cause xyssl to loop indefinitely by sending a certificate
       for which the RSA signature check fails (bug reported by Benoit)
     * Added test vectors for: AES-CBC, AES-CFB, DES-CBC and 3DES-CBC,
       HMAC-MD5, HMAC-SHA1, HMAC-SHA-256, HMAC-SHA-384, and HMAC-SHA-512
     * Fixed HMAC-SHA-384 and HMAC-SHA-512 (thanks to Josh Sinykin)
     * Modified ssl_parse_client_key_exchange() to protect against
       Daniel Bleichenbacher attack on PKCS#1 v1.5 padding, as well
       as the Klima-Pokorny-Rosa extension of Bleichenbacher's attack
     * Updated rsa_gen_key() so that ctx->N is always nbits in size
     * Fixed assembly PPC compilation errors on Mac OS X, thanks to
       David Barrett and Dusan Semen
 
 = Version 0.8 released on 2007-10-20
 
     * Modified the HMAC functions to handle keys larger
       than 64 bytes, thanks to Stephane Desneux and gary ng
     * Fixed ssl_read_record() to properly update the handshake
       message digests, which fixes IE6/IE7 client authentication
     * Cleaned up the XYSSL* #defines, suggested by Azriel Fasten
     * Fixed net_recv(), thanks to Lorenz Schori and Egon Kocjan
     * Added user-defined callbacks for handling I/O and sessions
     * Added lots of debugging output in the SSL/TLS functions
     * Added preliminary X.509 cert. writing by Pascal Vizeli
     * Added preliminary support for the VIA PadLock routines
     * Added AES-CFB mode of operation, contributed by chmike
     * Added an SSL/TLS stress testing program (ssl_test.c)
     * Updated the RSA PKCS#1 code to allow choosing between
       RSA_PUBLIC and RSA_PRIVATE, as suggested by David Barrett
     * Updated ssl_read() to skip 0-length records from OpenSSL
     * Fixed the make install target to comply with *BSD make
     * Fixed a bug in mpi_read_binary() on 64-bit platforms
     * mpi_is_prime() speedups, thanks to Kevin McLaughlin
     * Fixed a long standing memory leak in mpi_is_prime()
     * Replaced realloc with malloc in mpi_grow(), and set
       the sign of zero as positive in mpi_init() (reported
       by Jonathan M. McCune)
 
 = Version 0.7 released on 2007-07-07
 
     * Added support for the MicroBlaze soft-core processor
     * Fixed a bug in ssl_tls.c which sometimes prevented SSL
       connections from being established with non-blocking I/O
     * Fixed a couple bugs in the VS6 and UNIX Makefiles
     * Fixed the "PIC register ebx clobbered in asm" bug
     * Added HMAC starts/update/finish support functions
     * Added the SHA-224, SHA-384 and SHA-512 hash functions
     * Fixed the net_set_*block routines, thanks to Andreas
     * Added a few demonstration programs: md5sum, sha1sum,
       dh_client, dh_server, rsa_genkey, rsa_sign, rsa_verify
     * Added new bignum import and export helper functions
     * Rewrote README.txt in program/ssl/ca to better explain
       how to create a test PKI
 
 = Version 0.6 released on 2007-04-01
 
     * Ciphers used in SSL/TLS can now be disabled at compile
       time, to reduce the memory footprint on embedded systems
     * Added multiply assembly code for the TriCore and modified
       havege_struct for this processor, thanks to David Patiño
     * Added multiply assembly code for 64-bit PowerPCs,
       thanks to Peking University and the OSU Open Source Lab
     * Added experimental support of Quantum Cryptography
     * Added support for autoconf, contributed by Arnaud Cornet
     * Fixed "long long" compilation issues on IA-64 and PPC64
     * Fixed a bug introduced in xyssl-0.5/timing.c: hardclock
       was not being correctly defined on ARM and MIPS
 
 = Version 0.5 released on 2007-03-01
 
     * Added multiply assembly code for SPARC and Alpha
     * Added (beta) support for non-blocking I/O operations
     * Implemented session resuming and client authentication
     * Fixed some portability issues on WinCE, MINIX 3, Plan9
       (thanks to Benjamin Newman), HP-UX, FreeBSD and Solaris
     * Improved the performance of the EDH key exchange
     * Fixed a bug that caused valid packets with a payload
       size of 16384 bytes to be rejected
 
 = Version 0.4 released on 2007-02-01
 
     * Added support for Ephemeral Diffie-Hellman key exchange
     * Added multiply asm code for SSE2, ARM, PPC, MIPS and M68K
     * Various improvement to the modular exponentiation code
     * Rewrote the headers to generate the API docs with doxygen
     * Fixed a bug in ssl_encrypt_buf (incorrect padding was
       generated) and in ssl_parse_client_hello (max. client
       version was not properly set), thanks to Didier Rebeix
     * Fixed another bug in ssl_parse_client_hello: clients with
       cipherlists larger than 96 bytes were incorrectly rejected
     * Fixed a couple memory leak in x509_read.c
 
 = Version 0.3 released on 2007-01-01
 
     * Added server-side SSLv3 and TLSv1.0 support
     * Multiple fixes to enhance the compatibility with g++,
       thanks to Xosé Antón Otero Ferreira
     * Fixed a bug in the CBC code, thanks to dowst; also,
       the bignum code is no longer dependent on long long
     * Updated rsa_pkcs1_sign to handle arbitrary large inputs
     * Updated timing.c for improved compatibility with i386
       and 486 processors, thanks to Arnaud Cornet
 
 = Version 0.2 released on 2006-12-01
 
     * Updated timing.c to support ARM and MIPS arch
     * Updated the MPI code to support 8086 on MSVC 1.5
     * Added the copyright notice at the top of havege.h
     * Fixed a bug in sha2_hmac, thanks to newsoft/Wenfang Zhang
     * Fixed a bug reported by Adrian Rüegsegger in x509_read_key
     * Fixed a bug reported by Torsten Lauter in ssl_read_record
     * Fixed a bug in rsa_check_privkey that would wrongly cause
       valid RSA keys to be dismissed (thanks to oldwolf)
     * Fixed a bug in mpi_is_prime that caused some primes to fail
       the Miller-Rabin primality test
 
     I'd also like to thank Younès Hafri for the CRUX linux port,
     Khalil Petit who added XySSL into pkgsrc and Arnaud Cornet
     who maintains the Debian package :-)
 
 = Version 0.1 released on 2006-11-01