Mercurial > dropbear

comparison libtomcrypt/src/pk/pkcs1/pkcs_1_pss_decode.c @ 1511:5916af64acd4 fuzz

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
merge from main
author Matt Johnston <matt@ucc.asn.au>
date Sat, 17 Feb 2018 19:29:51 +0800
parents 6dba84798cd5
children
comparison
equal deleted inserted replaced
1457:32f990cc96b1 1511:5916af64acd4
3 * LibTomCrypt is a library that provides various cryptographic 3 * LibTomCrypt is a library that provides various cryptographic
4 * algorithms in a highly modular and flexible manner. 4 * algorithms in a highly modular and flexible manner.
5 * 5 *
6 * The library is free for all purposes without any express 6 * The library is free for all purposes without any express
7 * guarantee it works. 7 * guarantee it works.
8 *
9 * Tom St Denis, [email protected], http://libtom.org
10 */ 8 */
11 #include "tomcrypt.h" 9 #include "tomcrypt.h"
12 10
13 /** 11 /**
14 @file pkcs_1_pss_decode.c 12 @file pkcs_1_pss_decode.c
15 LTC_PKCS #1 PSS Signature Padding, Tom St Denis 13 PKCS #1 PSS Signature Padding, Tom St Denis
16 */ 14 */
17 15
18 #ifdef LTC_PKCS_1 16 #ifdef LTC_PKCS_1
19 17
20 /** 18 /**
21 LTC_PKCS #1 v2.00 PSS decode 19 PKCS #1 v2.00 PSS decode
22 @param msghash The hash to verify 20 @param msghash The hash to verify
23 @param msghashlen The length of the hash (octets) 21 @param msghashlen The length of the hash (octets)
24 @param sig The signature data (encoded data) 22 @param sig The signature data (encoded data)
25 @param siglen The length of the signature data (octets) 23 @param siglen The length of the signature data (octets)
26 @param saltlen The length of the salt used (octets) 24 @param saltlen The length of the salt used (octets)
49 if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { 47 if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) {
50 return err; 48 return err;
51 } 49 }
52 50
53 hLen = hash_descriptor[hash_idx].hashsize; 51 hLen = hash_descriptor[hash_idx].hashsize;
52 modulus_bitlen--;
54 modulus_len = (modulus_bitlen>>3) + (modulus_bitlen & 7 ? 1 : 0); 53 modulus_len = (modulus_bitlen>>3) + (modulus_bitlen & 7 ? 1 : 0);
55 54
56 /* check sizes */ 55 /* check sizes */
57 if ((saltlen > modulus_len) || 56 if ((saltlen > modulus_len) ||
58 (modulus_len < hLen + saltlen + 2) || (siglen != modulus_len)) { 57 (modulus_len < hLen + saltlen + 2)) {
59 return CRYPT_PK_INVALID_SIZE; 58 return CRYPT_PK_INVALID_SIZE;
60 } 59 }
61 60
62 /* allocate ram for DB/mask/salt/hash of size modulus_len */ 61 /* allocate ram for DB/mask/salt/hash of size modulus_len */
63 DB = XMALLOC(modulus_len); 62 DB = XMALLOC(modulus_len);
91 XMEMCPY(DB, sig + x, modulus_len - hLen - 1); 90 XMEMCPY(DB, sig + x, modulus_len - hLen - 1);
92 x += modulus_len - hLen - 1; 91 x += modulus_len - hLen - 1;
93 92
94 /* copy out the hash */ 93 /* copy out the hash */
95 XMEMCPY(hash, sig + x, hLen); 94 XMEMCPY(hash, sig + x, hLen);
96 x += hLen; 95 /* x += hLen; */
97 96
98 /* check the MSB */ 97 /* check the MSB */
99 if ((sig[0] & ~(0xFF >> ((modulus_len<<3) - (modulus_bitlen-1)))) != 0) { 98 if ((sig[0] & ~(0xFF >> ((modulus_len<<3) - (modulus_bitlen)))) != 0) {
100 err = CRYPT_INVALID_PACKET; 99 err = CRYPT_INVALID_PACKET;
101 goto LBL_ERR; 100 goto LBL_ERR;
102 } 101 }
103 102
104 /* generate mask of length modulus_len - hLen - 1 from hash */ 103 /* generate mask of length modulus_len - hLen - 1 from hash */
108 107
109 /* xor against DB */ 108 /* xor against DB */
110 for (y = 0; y < (modulus_len - hLen - 1); y++) { 109 for (y = 0; y < (modulus_len - hLen - 1); y++) {
111 DB[y] ^= mask[y]; 110 DB[y] ^= mask[y];
112 } 111 }
113 112
114 /* now clear the first byte [make sure smaller than modulus] */ 113 /* now clear the first byte [make sure smaller than modulus] */
115 DB[0] &= 0xFF >> ((modulus_len<<3) - (modulus_bitlen-1)); 114 DB[0] &= 0xFF >> ((modulus_len<<3) - (modulus_bitlen));
116 115
117 /* DB = PS || 0x01 || salt, PS == modulus_len - saltlen - hLen - 2 zero bytes */ 116 /* DB = PS || 0x01 || salt, PS == modulus_len - saltlen - hLen - 2 zero bytes */
118 117
119 /* check for zeroes and 0x01 */ 118 /* check for zeroes and 0x01 */
120 for (x = 0; x < modulus_len - saltlen - hLen - 2; x++) { 119 for (x = 0; x < modulus_len - saltlen - hLen - 2; x++) {
147 if ((err = hash_descriptor[hash_idx].done(&md, mask)) != CRYPT_OK) { 146 if ((err = hash_descriptor[hash_idx].done(&md, mask)) != CRYPT_OK) {
148 goto LBL_ERR; 147 goto LBL_ERR;
149 } 148 }
150 149
151 /* mask == hash means valid signature */ 150 /* mask == hash means valid signature */
152 if (XMEMCMP(mask, hash, hLen) == 0) { 151 if (XMEM_NEQ(mask, hash, hLen) == 0) {
153 *res = 1; 152 *res = 1;
154 } 153 }
155 154
156 err = CRYPT_OK; 155 err = CRYPT_OK;
157 LBL_ERR: 156 LBL_ERR:
158 #ifdef LTC_CLEAN_STACK 157 #ifdef LTC_CLEAN_STACK
159 zeromem(DB, modulus_len); 158 zeromem(DB, modulus_len);
160 zeromem(mask, modulus_len); 159 zeromem(mask, modulus_len);
161 zeromem(salt, modulus_len); 160 zeromem(salt, modulus_len);
162 zeromem(hash, modulus_len); 161 zeromem(hash, modulus_len);
163 #endif 162 #endif
164 163
165 XFREE(hash); 164 XFREE(hash);
166 XFREE(salt); 165 XFREE(salt);
167 XFREE(mask); 166 XFREE(mask);
170 return err; 169 return err;
171 } 170 }
172 171
173 #endif /* LTC_PKCS_1 */ 172 #endif /* LTC_PKCS_1 */
174 173
175 /* $Source$ */ 174 /* ref: $Format:%D$ */
176 /* $Revision$ */ 175 /* git commit: $Format:%H$ */
177 /* $Date$ */ 176 /* commit time: $Format:%ai$ */