Mercurial > dropbear
diff rsa_v15_verify_hash.c @ 143:5d99163f7e32 libtomcrypt-orig
import of libtomcrypt 0.99
author | Matt Johnston <matt@ucc.asn.au> |
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date | Sun, 19 Dec 2004 11:34:45 +0000 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/rsa_v15_verify_hash.c Sun Dec 19 11:34:45 2004 +0000 @@ -0,0 +1,72 @@ +/* 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.org + */ + +#include "mycrypt.h" + +#ifdef MRSA + +/* de-sign then PKCS v1.5 depad */ +int rsa_v15_verify_hash(const unsigned char *sig, unsigned long siglen, + const unsigned char *msghash, unsigned long msghashlen, + prng_state *prng, int prng_idx, + int hash_idx, int *stat, + rsa_key *key) +{ + unsigned long modulus_bitlen, modulus_bytelen, x; + int err; + unsigned char *tmpbuf; + + _ARGCHK(msghash != NULL); + _ARGCHK(sig != NULL); + _ARGCHK(stat != NULL); + _ARGCHK(key != NULL); + + /* default to invalid */ + *stat = 0; + + /* valid hash ? */ + if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { + return err; + } + + if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) { + return err; + } + + /* get modulus len in bits */ + modulus_bitlen = mp_count_bits(&(key->N)); + + /* outlen must be at least the size of the modulus */ + modulus_bytelen = mp_unsigned_bin_size(&(key->N)); + if (modulus_bytelen != siglen) { + return CRYPT_INVALID_PACKET; + } + + /* allocate temp buffer for decoded sig */ + tmpbuf = XMALLOC(siglen); + if (tmpbuf == NULL) { + return CRYPT_MEM; + } + + /* RSA decode it */ + x = siglen; + if ((err = rsa_exptmod(sig, siglen, tmpbuf, &x, PK_PUBLIC, prng, prng_idx, key)) != CRYPT_OK) { + XFREE(tmpbuf); + return err; + } + + /* PSS decode it */ + err = pkcs_1_v15_sa_decode(msghash, msghashlen, tmpbuf, x, hash_idx, modulus_bitlen, stat); + XFREE(tmpbuf); + return err; +} + +#endif