Mercurial > dropbear

annotate libtomcrypt/src/pk/dsa/dsa_verify_hash.c @ 289:497fddd4a94e

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code was untested and wrong.
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 15:46:24 +0000
parents 1b9e69c058d2
children 0cbe8f6dbf9e
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
285
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diff changeset
1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
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2 *
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3 * LibTomCrypt is a library that provides various cryptographic
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4 * algorithms in a highly modular and flexible manner.
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5 *
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6 * The library is free for all purposes without any express
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7 * guarantee it works.
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8 *
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diff changeset
9 * Tom St Denis, [email protected], http://libtomcrypt.org
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10 */
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diff changeset
11 #include "tomcrypt.h"
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12
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13 /**
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diff changeset
14 @file dsa_verify_hash.c
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diff changeset
15 DSA implementation, verify a signature, Tom St Denis
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16 */
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17
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18
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
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19 #ifdef MDSA
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20
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21 /**
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22 Verify a DSA signature
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23 @param r DSA "r" parameter
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24 @param s DSA "s" parameter
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25 @param hash The hash that was signed
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26 @param hashlen The length of the hash that was signed
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27 @param stat [out] The result of the signature verification, 1==valid, 0==invalid
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28 @param key The corresponding public DH key
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29 @return CRYPT_OK if successful (even if the signature is invalid)
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30 */
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31 int dsa_verify_hash_raw( mp_int *r, mp_int *s,
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32 const unsigned char *hash, unsigned long hashlen,
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33 int *stat, dsa_key *key)
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34 {
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35 mp_int w, v, u1, u2;
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36 int err;
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37
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38 LTC_ARGCHK(r != NULL);
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39 LTC_ARGCHK(s != NULL);
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40 LTC_ARGCHK(stat != NULL);
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41 LTC_ARGCHK(key != NULL);
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42
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43 /* default to invalid signature */
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44 *stat = 0;
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45
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
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46 /* init our variables */
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47 if ((err = mp_init_multi(&w, &v, &u1, &u2, NULL)) != MP_OKAY) {
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48 return mpi_to_ltc_error(err);
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49 }
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50
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51 /* neither r or s can be null or >q*/
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52 if (mp_iszero(r) == MP_YES || mp_iszero(s) == MP_YES || mp_cmp(r, &key->q) != MP_LT || mp_cmp(s, &key->q) != MP_LT) {
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53 err = CRYPT_INVALID_PACKET;
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54 goto done;
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55 }
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56
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57 /* w = 1/s mod q */
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58 if ((err = mp_invmod(s, &key->q, &w)) != MP_OKAY) { goto error; }
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59
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60 /* u1 = m * w mod q */
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61 if ((err = mp_read_unsigned_bin(&u1, (unsigned char *)hash, hashlen)) != MP_OKAY) { goto error; }
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62 if ((err = mp_mulmod(&u1, &w, &key->q, &u1)) != MP_OKAY) { goto error; }
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63
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64 /* u2 = r*w mod q */
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65 if ((err = mp_mulmod(r, &w, &key->q, &u2)) != MP_OKAY) { goto error; }
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66
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67 /* v = g^u1 * y^u2 mod p mod q */
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68 if ((err = mp_exptmod(&key->g, &u1, &key->p, &u1)) != MP_OKAY) { goto error; }
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
69 if ((err = mp_exptmod(&key->y, &u2, &key->p, &u2)) != MP_OKAY) { goto error; }
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70 if ((err = mp_mulmod(&u1, &u2, &key->p, &v)) != MP_OKAY) { goto error; }
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
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diff changeset
71 if ((err = mp_mod(&v, &key->q, &v)) != MP_OKAY) { goto error; }
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72
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
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diff changeset
73 /* if r = v then we're set */
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
74 if (mp_cmp(r, &v) == MP_EQ) {
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
75 *stat = 1;
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76 }
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77
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
78 err = CRYPT_OK;
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Matt Johnston <matt@ucc.asn.au>
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79 goto done;
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
80
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
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diff changeset
81 error : err = mpi_to_ltc_error(err);
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
82 done : mp_clear_multi(&w, &v, &u1, &u2, NULL);
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
83 return err;
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84 }
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
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85
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
86 /**
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diff changeset
87 Verify a DSA signature
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
88 @param sig The signature
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
89 @param siglen The length of the signature (octets)
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
90 @param hash The hash that was signed
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
91 @param hashlen The length of the hash that was signed
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
92 @param stat [out] The result of the signature verification, 1==valid, 0==invalid
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
93 @param key The corresponding public DH key
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
94 @return CRYPT_OK if successful (even if the signature is invalid)
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
95 */
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
96 int dsa_verify_hash(const unsigned char *sig, unsigned long siglen,
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
97 const unsigned char *hash, unsigned long hashlen,
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
98 int *stat, dsa_key *key)
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
99 {
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
100 int err;
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
101 mp_int r, s;
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
102
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
103 if ((err = mp_init_multi(&r, &s, NULL)) != CRYPT_OK) {
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
104 return CRYPT_MEM;
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
105 }
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
106
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
107 /* decode the sequence */
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
108 if ((err = der_decode_sequence_multi(sig, siglen,
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
109 LTC_ASN1_INTEGER, 1UL, &r,
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
110 LTC_ASN1_INTEGER, 1UL, &s,
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
111 LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) {
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
112 goto LBL_ERR;
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
113 }
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
114
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
115 /* do the op */
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
116 err = dsa_verify_hash_raw(&r, &s, hash, hashlen, stat, key);
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
117
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
118 LBL_ERR:
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
119 mp_clear_multi(&r, &s, NULL);
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
120 return err;
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
121 }
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
122
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
123 #endif
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
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124
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
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125
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
126 /* $Source: /cvs/libtom/libtomcrypt/src/pk/dsa/dsa_verify_hash.c,v $ */
1b9e69c058d2 propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
127 /* $Revision: 1.8 $ */
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
128 /* $Date: 2005/05/15 21:48:59 $ */