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comparison libtomcrypt/src/pk/dsa/dsa_verify_hash.c @ 1471:6dba84798cd5

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Update to libtomcrypt 1.18.1, merged with Dropbear changes
author Matt Johnston <matt@ucc.asn.au>
date Fri, 09 Feb 2018 21:44:05 +0800
parents f849a5ca2efc
children
comparison
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1470:8bba51a55704 1471:6dba84798cd5
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 dsa_verify_hash.c 12 @file dsa_verify_hash.c
23 @param r DSA "r" parameter 21 @param r DSA "r" parameter
24 @param s DSA "s" parameter 22 @param s DSA "s" parameter
25 @param hash The hash that was signed 23 @param hash The hash that was signed
26 @param hashlen The length of the hash that was signed 24 @param hashlen The length of the hash that was signed
27 @param stat [out] The result of the signature verification, 1==valid, 0==invalid 25 @param stat [out] The result of the signature verification, 1==valid, 0==invalid
28 @param key The corresponding public DH key 26 @param key The corresponding public DSA key
29 @return CRYPT_OK if successful (even if the signature is invalid) 27 @return CRYPT_OK if successful (even if the signature is invalid)
30 */ 28 */
31 int dsa_verify_hash_raw( void *r, void *s, 29 int dsa_verify_hash_raw( void *r, void *s,
32 const unsigned char *hash, unsigned long hashlen, 30 const unsigned char *hash, unsigned long hashlen,
33 int *stat, dsa_key *key) 31 int *stat, dsa_key *key)
34 { 32 {
35 void *w, *v, *u1, *u2; 33 void *w, *v, *u1, *u2;
36 int err; 34 int err;
37 35
47 if ((err = mp_init_multi(&w, &v, &u1, &u2, NULL)) != CRYPT_OK) { 45 if ((err = mp_init_multi(&w, &v, &u1, &u2, NULL)) != CRYPT_OK) {
48 return err; 46 return err;
49 } 47 }
50 48
51 /* neither r or s can be null or >q*/ 49 /* neither r or s can be null or >q*/
52 if (mp_iszero(r) == LTC_MP_YES || mp_iszero(s) == LTC_MP_YES || mp_cmp(r, key->q) != LTC_MP_LT || mp_cmp(s, key->q) != LTC_MP_LT) { 50 if (mp_cmp_d(r, 0) != LTC_MP_GT || mp_cmp_d(s, 0) != LTC_MP_GT || mp_cmp(r, key->q) != LTC_MP_LT || mp_cmp(s, key->q) != LTC_MP_LT) {
53 err = CRYPT_INVALID_PACKET; 51 err = CRYPT_INVALID_PACKET;
54 goto error; 52 goto error;
55 } 53 }
56 54
55 /* FIPS 186-4 4.7: use leftmost min(bitlen(q), bitlen(hash)) bits of 'hash' */
56 hashlen = MIN(hashlen, (unsigned long)(key->qord));
57
57 /* w = 1/s mod q */ 58 /* w = 1/s mod q */
58 if ((err = mp_invmod(s, key->q, w)) != CRYPT_OK) { goto error; } 59 if ((err = mp_invmod(s, key->q, w)) != CRYPT_OK) { goto error; }
59 60
60 /* u1 = m * w mod q */ 61 /* u1 = m * w mod q */
61 if ((err = mp_read_unsigned_bin(u1, (unsigned char *)hash, hashlen)) != CRYPT_OK) { goto error; } 62 if ((err = mp_read_unsigned_bin(u1, (unsigned char *)hash, hashlen)) != CRYPT_OK) { goto error; }
62 if ((err = mp_mulmod(u1, w, key->q, u1)) != CRYPT_OK) { goto error; } 63 if ((err = mp_mulmod(u1, w, key->q, u1)) != CRYPT_OK) { goto error; }
63 64
64 /* u2 = r*w mod q */ 65 /* u2 = r*w mod q */
65 if ((err = mp_mulmod(r, w, key->q, u2)) != CRYPT_OK) { goto error; } 66 if ((err = mp_mulmod(r, w, key->q, u2)) != CRYPT_OK) { goto error; }
66 67
67 /* v = g^u1 * y^u2 mod p mod q */ 68 /* v = g^u1 * y^u2 mod p mod q */
68 if ((err = mp_exptmod(key->g, u1, key->p, u1)) != CRYPT_OK) { goto error; } 69 if ((err = mp_exptmod(key->g, u1, key->p, u1)) != CRYPT_OK) { goto error; }
69 if ((err = mp_exptmod(key->y, u2, key->p, u2)) != CRYPT_OK) { goto error; } 70 if ((err = mp_exptmod(key->y, u2, key->p, u2)) != CRYPT_OK) { goto error; }
70 if ((err = mp_mulmod(u1, u2, key->p, v)) != CRYPT_OK) { goto error; } 71 if ((err = mp_mulmod(u1, u2, key->p, v)) != CRYPT_OK) { goto error; }
86 @param sig The signature 87 @param sig The signature
87 @param siglen The length of the signature (octets) 88 @param siglen The length of the signature (octets)
88 @param hash The hash that was signed 89 @param hash The hash that was signed
89 @param hashlen The length of the hash that was signed 90 @param hashlen The length of the hash that was signed
90 @param stat [out] The result of the signature verification, 1==valid, 0==invalid 91 @param stat [out] The result of the signature verification, 1==valid, 0==invalid
91 @param key The corresponding public DH key 92 @param key The corresponding public DSA key
92 @return CRYPT_OK if successful (even if the signature is invalid) 93 @return CRYPT_OK if successful (even if the signature is invalid)
93 */ 94 */
94 int dsa_verify_hash(const unsigned char *sig, unsigned long siglen, 95 int dsa_verify_hash(const unsigned char *sig, unsigned long siglen,
95 const unsigned char *hash, unsigned long hashlen, 96 const unsigned char *hash, unsigned long hashlen,
96 int *stat, dsa_key *key) 97 int *stat, dsa_key *key)
97 { 98 {
98 int err; 99 int err;
99 void *r, *s; 100 void *r, *s;
101 ltc_asn1_list sig_seq[2];
102 unsigned long reallen = 0;
103
104 LTC_ARGCHK(stat != NULL);
105 *stat = 0; /* must be set before the first return */
100 106
101 if ((err = mp_init_multi(&r, &s, NULL)) != CRYPT_OK) { 107 if ((err = mp_init_multi(&r, &s, NULL)) != CRYPT_OK) {
102 return CRYPT_MEM; 108 return err;
103 } 109 }
104 110
105 /* decode the sequence */ 111 LTC_SET_ASN1(sig_seq, 0, LTC_ASN1_INTEGER, r, 1UL);
106 if ((err = der_decode_sequence_multi(sig, siglen, 112 LTC_SET_ASN1(sig_seq, 1, LTC_ASN1_INTEGER, s, 1UL);
107 LTC_ASN1_INTEGER, 1UL, r, 113
108 LTC_ASN1_INTEGER, 1UL, s, 114 err = der_decode_sequence(sig, siglen, sig_seq, 2);
109 LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) { 115 if (err != CRYPT_OK) {
116 goto LBL_ERR;
117 }
118
119 err = der_length_sequence(sig_seq, 2, &reallen);
120 if (err != CRYPT_OK || reallen != siglen) {
110 goto LBL_ERR; 121 goto LBL_ERR;
111 } 122 }
112 123
113 /* do the op */ 124 /* do the op */
114 err = dsa_verify_hash_raw(r, s, hash, hashlen, stat, key); 125 err = dsa_verify_hash_raw(r, s, hash, hashlen, stat, key);
119 } 130 }
120 131
121 #endif 132 #endif
122 133
123 134
124 /* $Source$ */ 135 /* ref: $Format:%D$ */
125 /* $Revision$ */ 136 /* git commit: $Format:%H$ */
126 /* $Date$ */ 137 /* commit time: $Format:%ai$ */