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comparison rsa_v15_sign_hash.c @ 143:5d99163f7e32 libtomcrypt-orig

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import of libtomcrypt 0.99
author Matt Johnston <matt@ucc.asn.au>
date Sun, 19 Dec 2004 11:34:45 +0000
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15:6362d3854bb4 143:5d99163f7e32
1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
2 *
3 * LibTomCrypt is a library that provides various cryptographic
4 * algorithms in a highly modular and flexible manner.
5 *
6 * The library is free for all purposes without any express
7 * guarantee it works.
8 *
9 * Tom St Denis, [email protected], http://libtomcrypt.org
10 */
11
12 #include "mycrypt.h"
13
14 #ifdef MRSA
15
16 /* PKCS #1 v1.5 pad then sign */
17 int rsa_v15_sign_hash(const unsigned char *msghash, unsigned long msghashlen,
18 unsigned char *sig, unsigned long *siglen,
19 prng_state *prng, int prng_idx,
20 int hash_idx, rsa_key *key)
21 {
22 unsigned long modulus_bitlen, modulus_bytelen, x;
23 int err;
24
25 _ARGCHK(msghash != NULL);
26 _ARGCHK(sig != NULL);
27 _ARGCHK(siglen != NULL);
28 _ARGCHK(key != NULL);
29
30 /* valid prng and hash ? */
31 if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) {
32 return err;
33 }
34 if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) {
35 return err;
36 }
37
38 /* get modulus len in bits */
39 modulus_bitlen = mp_count_bits(&(key->N));
40
41 /* outlen must be at least the size of the modulus */
42 modulus_bytelen = mp_unsigned_bin_size(&(key->N));
43 if (modulus_bytelen > *siglen) {
44 return CRYPT_BUFFER_OVERFLOW;
45 }
46
47 /* PKCS #1 v1.5 pad the key */
48 x = *siglen;
49 if ((err = pkcs_1_v15_sa_encode(msghash, msghashlen, hash_idx, modulus_bitlen, sig, &x)) != CRYPT_OK) {
50 return err;
51 }
52
53 /* RSA encode it */
54 return rsa_exptmod(sig, x, sig, siglen, PK_PRIVATE, prng, prng_idx, key);
55 }
56
57 #endif