Mercurial > dropbear

comparison pkcs_1_v15_es_decode.c @ 15:6362d3854bb4 libtomcrypt-orig

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
0.96 release of LibTomCrypt
author Matt Johnston <matt@ucc.asn.au>
date Tue, 15 Jun 2004 14:07:21 +0000
parents
children 5d99163f7e32
comparison
equal deleted inserted replaced
3:7faae8f46238 15:6362d3854bb4
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 #include "mycrypt.h"
12
13 /* PKCS #1 v1.5 Encryption Padding -- Tom St Denis */
14
15 #ifdef PKCS_1
16
17 int pkcs_1_v15_es_decode(const unsigned char *msg, unsigned long msglen,
18 unsigned long modulus_bitlen,
19 unsigned char *out, unsigned long outlen,
20 int *res)
21 {
22 unsigned long x, modulus_bytelen;
23
24 _ARGCHK(msg != NULL);
25 _ARGCHK(out != NULL);
26 _ARGCHK(res != NULL);
27
28 /* default to failed */
29 *res = 0;
30
31 /* must be at least 12 bytes long */
32 if (msglen < 12) {
33 return CRYPT_INVALID_ARG;
34 }
35
36 modulus_bytelen = (modulus_bitlen>>3) + (modulus_bitlen & 7 ? 1 : 0);
37
38 /* should start with 0x00 0x02 */
39 if (msg[0] != 0x00 || msg[1] != 0x02) {
40 return CRYPT_OK;
41 }
42
43 /* skip over PS */
44 x = 2 + (modulus_bytelen - outlen - 3);
45
46 /* should be 0x00 */
47 if (msg[x++] != 0x00) {
48 return CRYPT_OK;
49 }
50
51 /* the message is left */
52 if (x + outlen > modulus_bytelen) {
53 return CRYPT_PK_INVALID_SIZE;
54 }
55 memcpy(out, msg + x, outlen);
56 *res = 1;
57 return CRYPT_OK;
58 }
59
60 #endif
61