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comparison rsa_v15_decrypt_key.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 /* decrypt then PKCS #1 v1.5 depad */
17 int rsa_v15_decrypt_key(const unsigned char *in, unsigned long inlen,
18 unsigned char *outkey, unsigned long keylen,
19 prng_state *prng, int prng_idx,
20 int *res, rsa_key *key)
21 {
22 unsigned long modulus_bitlen, modulus_bytelen, x;
23 int err;
24 unsigned char *tmp;
25
26 _ARGCHK(outkey != NULL);
27 _ARGCHK(key != NULL);
28 _ARGCHK(res != NULL);
29
30 /* default to invalid */
31 *res = 0;
32
33 /* valid prng ? */
34 if ((err = prng_is_valid(prng_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 != inlen) {
44 return CRYPT_INVALID_PACKET;
45 }
46
47 /* allocate ram */
48 tmp = XMALLOC(inlen);
49 if (tmp == NULL) {
50 return CRYPT_MEM;
51 }
52
53 /* rsa decode the packet */
54 x = inlen;
55 if ((err = rsa_exptmod(in, inlen, tmp, &x, PK_PRIVATE, prng, prng_idx, key)) != CRYPT_OK) {
56 XFREE(tmp);
57 return err;
58 }
59
60 /* PKCS #1 v1.5 depad */
61 err = pkcs_1_v15_es_decode(tmp, x, modulus_bitlen, outkey, keylen, res);
62 XFREE(tmp);
63 return err;
64 }
65
66 #endif