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Diffstat (limited to 'deps/openssl/openssl/doc/man3/EVP_DigestVerifyInit.pod')
| -rw-r--r-- | deps/openssl/openssl/doc/man3/EVP_DigestVerifyInit.pod | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/deps/openssl/openssl/doc/man3/EVP_DigestVerifyInit.pod b/deps/openssl/openssl/doc/man3/EVP_DigestVerifyInit.pod new file mode 100644 index 0000000000..e93ac2ef08 --- /dev/null +++ b/deps/openssl/openssl/doc/man3/EVP_DigestVerifyInit.pod @@ -0,0 +1,112 @@ +=pod + +=head1 NAME + +EVP_DigestVerifyInit, EVP_DigestVerifyUpdate, EVP_DigestVerifyFinal, +EVP_DigestVerify - EVP signature verification functions + +=head1 SYNOPSIS + + #include <openssl/evp.h> + + int EVP_DigestVerifyInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx, + const EVP_MD *type, ENGINE *e, EVP_PKEY *pkey); + int EVP_DigestVerifyUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt); + int EVP_DigestVerifyFinal(EVP_MD_CTX *ctx, const unsigned char *sig, + size_t siglen); + int EVP_DigestVerify(EVP_MD_CTX *ctx, const unsigned char *sigret, + size_t siglen, const unsigned char *tbs, size_t tbslen); + +=head1 DESCRIPTION + +The EVP signature routines are a high level interface to digital signatures. + +EVP_DigestVerifyInit() sets up verification context B<ctx> to use digest +B<type> from ENGINE B<e> and public key B<pkey>. B<ctx> must be created +with EVP_MD_CTX_new() before calling this function. If B<pctx> is not NULL, the +EVP_PKEY_CTX of the verification operation will be written to B<*pctx>: this +can be used to set alternative verification options. Note that any existing +value in B<*pctx> is overwritten. The EVP_PKEY_CTX value returned must not be freed +directly by the application if B<ctx> is not assigned an EVP_PKEY_CTX value before +being passed to EVP_DigestSignInit() (which means the EVP_PKEY_CTX is created +inside EVP_DigestSignInit() and it will be freed automatically when the +EVP_MD_CTX is freed). + +No B<EVP_PKEY_CTX> will be created by EVP_DigsetSignInit() if the passed B<ctx> +has already been assigned one via L<EVP_MD_CTX_set_ctx(3)>. See also L<SM2(7)>. + +EVP_DigestVerifyUpdate() hashes B<cnt> bytes of data at B<d> into the +verification context B<ctx>. This function can be called several times on the +same B<ctx> to include additional data. This function is currently implemented +using a macro. + +EVP_DigestVerifyFinal() verifies the data in B<ctx> against the signature in +B<sig> of length B<siglen>. + +EVP_DigestVerify() verifies B<tbslen> bytes at B<tbs> against the signature +in B<sig> of length B<siglen>. + +=head1 RETURN VALUES + +EVP_DigestVerifyInit() and EVP_DigestVerifyUpdate() return 1 for success and 0 +for failure. + +EVP_DigestVerifyFinal() and EVP_DigestVerify() return 1 for success; any other +value indicates failure. A return value of zero indicates that the signature +did not verify successfully (that is, B<tbs> did not match the original data or +the signature had an invalid form), while other values indicate a more serious +error (and sometimes also indicate an invalid signature form). + +The error codes can be obtained from L<ERR_get_error(3)>. + +=head1 NOTES + +The B<EVP> interface to digital signatures should almost always be used in +preference to the low level interfaces. This is because the code then becomes +transparent to the algorithm used and much more flexible. + +EVP_DigestVerify() is a one shot operation which verifies a single block of +data in one function. For algorithms that support streaming it is equivalent +to calling EVP_DigestVerifyUpdate() and EVP_DigestVerifyFinal(). For +algorithms which do not support streaming (e.g. PureEdDSA) it is the only way +to verify data. + +In previous versions of OpenSSL there was a link between message digest types +and public key algorithms. This meant that "clone" digests such as EVP_dss1() +needed to be used to sign using SHA1 and DSA. This is no longer necessary and +the use of clone digest is now discouraged. + +For some key types and parameters the random number generator must be seeded +or the operation will fail. + +The call to EVP_DigestVerifyFinal() internally finalizes a copy of the digest +context. This means that EVP_VerifyUpdate() and EVP_VerifyFinal() can +be called later to digest and verify additional data. + +Since only a copy of the digest context is ever finalized, the context must +be cleaned up after use by calling EVP_MD_CTX_free() or a memory leak +will occur. + +=head1 SEE ALSO + +L<EVP_DigestSignInit(3)>, +L<EVP_DigestInit(3)>, +L<evp(7)>, L<HMAC(3)>, L<MD2(3)>, +L<MD5(3)>, L<MDC2(3)>, L<RIPEMD160(3)>, +L<SHA1(3)>, L<dgst(1)> + +=head1 HISTORY + +EVP_DigestVerifyInit(), EVP_DigestVerifyUpdate() and EVP_DigestVerifyFinal() +were first added to OpenSSL 1.0.0. + +=head1 COPYRIGHT + +Copyright 2006-2018 The OpenSSL Project Authors. All Rights Reserved. + +Licensed under the OpenSSL license (the "License"). You may not use +this file except in compliance with the License. You can obtain a copy +in the file LICENSE in the source distribution or at +L<https://www.openssl.org/source/license.html>. + +=cut |