Mercurial > dropbear
view libtomcrypt/src/pk/pkcs1/pkcs_1_v1_5_decode.c @ 922:3a32abe076fc coverity
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author | Matt Johnston <matt@ucc.asn.au> |
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date | Sat, 08 Mar 2014 21:00:32 +0800 |
parents | 0cbe8f6dbf9e |
children | f849a5ca2efc |
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis * * LibTomCrypt is a library that provides various cryptographic * algorithms in a highly modular and flexible manner. * * The library is free for all purposes without any express * guarantee it works. * * Tom St Denis, [email protected], http://libtomcrypt.com */ #include "tomcrypt.h" /** @file pkcs_1_v1_5_decode.c * * PKCS #1 v1.5 Padding. (Andreas Lange) */ #ifdef PKCS_1 /** @brief PKCS #1 v1.5 decode. * * @param msg The encoded data to decode * @param msglen The length of the encoded data (octets) * @param block_type Block type to use in padding (\sa ltc_pkcs_1_v1_5_blocks) * @param modulus_bitlen The bit length of the RSA modulus * @param out [out] Destination of decoding * @param outlen [in/out] The max size and resulting size of the decoding * @param is_valid [out] Boolean whether the padding was valid * * @return CRYPT_OK if successful (even if invalid) */ int pkcs_1_v1_5_decode(const unsigned char *msg, unsigned long msglen, int block_type, unsigned long modulus_bitlen, unsigned char *out, unsigned long *outlen, int *is_valid) { unsigned long modulus_len, ps_len, i; int result; /* default to invalid packet */ *is_valid = 0; modulus_len = (modulus_bitlen >> 3) + (modulus_bitlen & 7 ? 1 : 0); /* test message size */ if ((msglen > modulus_len) || (modulus_len < 11)) { return CRYPT_PK_INVALID_SIZE; } /* separate encoded message */ if ((msg[0] != 0x00) || (msg[1] != (unsigned char)block_type)) { result = CRYPT_INVALID_PACKET; goto bail; } if (block_type == LTC_PKCS_1_EME) { for (i = 2; i < modulus_len; i++) { /* separator */ if (msg[i] == 0x00) { break; } } ps_len = i++ - 2; if ((i >= modulus_len) || (ps_len < 8)) { /* There was no octet with hexadecimal value 0x00 to separate ps from m, * or the length of ps is less than 8 octets. */ result = CRYPT_INVALID_PACKET; goto bail; } } else { for (i = 2; i < modulus_len - 1; i++) { if (msg[i] != 0xFF) { break; } } /* separator check */ if (msg[i] != 0) { /* There was no octet with hexadecimal value 0x00 to separate ps from m. */ result = CRYPT_INVALID_PACKET; goto bail; } ps_len = i - 2; } if (*outlen < (msglen - (2 + ps_len + 1))) { *outlen = msglen - (2 + ps_len + 1); result = CRYPT_BUFFER_OVERFLOW; goto bail; } *outlen = (msglen - (2 + ps_len + 1)); XMEMCPY(out, &msg[2 + ps_len + 1], *outlen); /* valid packet */ *is_valid = 1; result = CRYPT_OK; bail: return result; } /* pkcs_1_v1_5_decode */ #endif /* #ifdef PKCS_1 */ /* $Source: /cvs/libtom/libtomcrypt/src/pk/pkcs1/pkcs_1_v1_5_decode.c,v $ */ /* $Revision: 1.5 $ */ /* $Date: 2006/12/16 17:41:21 $ */