diff options
Diffstat (limited to 'deps/openssl/openssl/crypto/rsa/rsa_pk1.c')
-rw-r--r-- | deps/openssl/openssl/crypto/rsa/rsa_pk1.c | 46 |
1 files changed, 23 insertions, 23 deletions
diff --git a/deps/openssl/openssl/crypto/rsa/rsa_pk1.c b/deps/openssl/openssl/crypto/rsa/rsa_pk1.c index 0626907418..5260d12f4c 100644 --- a/deps/openssl/openssl/crypto/rsa/rsa_pk1.c +++ b/deps/openssl/openssl/crypto/rsa/rsa_pk1.c @@ -1,5 +1,5 @@ /* - * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved. + * Copyright 1995-2019 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 @@ -192,15 +192,14 @@ int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen, from -= 1 & mask; *--em = *from & mask; } - from = em; - good = constant_time_is_zero(from[0]); - good &= constant_time_eq(from[1], 2); + good = constant_time_is_zero(em[0]); + good &= constant_time_eq(em[1], 2); /* scan over padding data */ found_zero_byte = 0; for (i = 2; i < num; i++) { - unsigned int equals0 = constant_time_is_zero(from[i]); + unsigned int equals0 = constant_time_is_zero(em[i]); zero_index = constant_time_select_int(~found_zero_byte & equals0, i, zero_index); @@ -208,7 +207,7 @@ int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen, } /* - * PS must be at least 8 bytes long, and it starts two bytes into |from|. + * PS must be at least 8 bytes long, and it starts two bytes into |em|. * If we never found a 0-byte, then |zero_index| is 0 and the check * also fails. */ @@ -227,24 +226,25 @@ int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen, good &= constant_time_ge(tlen, mlen); /* - * Even though we can't fake result's length, we can pretend copying - * |tlen| bytes where |mlen| bytes would be real. Last |tlen| of |num| - * bytes are viewed as circular buffer with start at |tlen|-|mlen'|, - * where |mlen'| is "saturated" |mlen| value. Deducing information - * about failure or |mlen| would take attacker's ability to observe - * memory access pattern with byte granularity *as it occurs*. It - * should be noted that failure is indistinguishable from normal - * operation if |tlen| is fixed by protocol. + * Move the result in-place by |num|-11-|mlen| bytes to the left. + * Then if |good| move |mlen| bytes from |em|+11 to |to|. + * Otherwise leave |to| unchanged. + * Copy the memory back in a way that does not reveal the size of + * the data being copied via a timing side channel. This requires copying + * parts of the buffer multiple times based on the bits set in the real + * length. Clear bits do a non-copy with identical access pattern. + * The loop below has overall complexity of O(N*log(N)). */ - tlen = constant_time_select_int(constant_time_lt(num, tlen), num, tlen); - msg_index = constant_time_select_int(good, msg_index, num - tlen); - mlen = num - msg_index; - for (from += msg_index, mask = good, i = 0; i < tlen; i++) { - unsigned int equals = constant_time_eq(i, mlen); - - from -= tlen & equals; /* if (i == mlen) rewind */ - mask &= mask ^ equals; /* if (i == mlen) mask = 0 */ - to[i] = constant_time_select_8(mask, from[i], to[i]); + tlen = constant_time_select_int(constant_time_lt(num - 11, tlen), + num - 11, tlen); + for (msg_index = 1; msg_index < num - 11; msg_index <<= 1) { + mask = ~constant_time_eq(msg_index & (num - 11 - mlen), 0); + for (i = 11; i < num - msg_index; i++) + em[i] = constant_time_select_8(mask, em[i + msg_index], em[i]); + } + for (i = 0; i < tlen; i++) { + mask = good & constant_time_lt(i, mlen); + to[i] = constant_time_select_8(mask, em[i + 11], to[i]); } OPENSSL_clear_free(em, num); |