wolf SSL / CyaSSL-2.9.4

SSL/TLS Library

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CyaSSL is SSL/TLS library for embedded systems.

wolfssl.com

ctaocrypt/src/dsa.c@0:9d17e4342598, 2014-04-20 (annotated)

Committer:
wolfSSL
Date:
Sun Apr 20 12:40:57 2014 +0000
Revision:
0:9d17e4342598
CyaSSL SSL/TLS Library 2.9.4;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
wolfSSL 0:9d17e4342598 1 /* dsa.c
wolfSSL 0:9d17e4342598 2 *
wolfSSL 0:9d17e4342598 3 * Copyright (C) 2006-2013 wolfSSL Inc.
wolfSSL 0:9d17e4342598 4 *
wolfSSL 0:9d17e4342598 5 * This file is part of CyaSSL.
wolfSSL 0:9d17e4342598 6 *
wolfSSL 0:9d17e4342598 7 * CyaSSL is free software; you can redistribute it and/or modify
wolfSSL 0:9d17e4342598 8 * it under the terms of the GNU General Public License as published by
wolfSSL 0:9d17e4342598 9 * the Free Software Foundation; either version 2 of the License, or
wolfSSL 0:9d17e4342598 10 * (at your option) any later version.
wolfSSL 0:9d17e4342598 11 *
wolfSSL 0:9d17e4342598 12 * CyaSSL is distributed in the hope that it will be useful,
wolfSSL 0:9d17e4342598 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
wolfSSL 0:9d17e4342598 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
wolfSSL 0:9d17e4342598 15 * GNU General Public License for more details.
wolfSSL 0:9d17e4342598 16 *
wolfSSL 0:9d17e4342598 17 * You should have received a copy of the GNU General Public License
wolfSSL 0:9d17e4342598 18 * along with this program; if not, write to the Free Software
wolfSSL 0:9d17e4342598 19 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
wolfSSL 0:9d17e4342598 20 */
wolfSSL 0:9d17e4342598 21
wolfSSL 0:9d17e4342598 22 #ifdef HAVE_CONFIG_H
wolfSSL 0:9d17e4342598 23 #include <config.h>
wolfSSL 0:9d17e4342598 24 #endif
wolfSSL 0:9d17e4342598 25
wolfSSL 0:9d17e4342598 26 #include <cyassl/ctaocrypt/settings.h>
wolfSSL 0:9d17e4342598 27
wolfSSL 0:9d17e4342598 28 #ifndef NO_DSA
wolfSSL 0:9d17e4342598 29
wolfSSL 0:9d17e4342598 30 #include <cyassl/ctaocrypt/dsa.h>
wolfSSL 0:9d17e4342598 31 #include <cyassl/ctaocrypt/sha.h>
wolfSSL 0:9d17e4342598 32 #include <cyassl/ctaocrypt/random.h>
wolfSSL 0:9d17e4342598 33 #include <cyassl/ctaocrypt/error-crypt.h>
wolfSSL 0:9d17e4342598 34
wolfSSL 0:9d17e4342598 35
wolfSSL 0:9d17e4342598 36 enum {
wolfSSL 0:9d17e4342598 37 DSA_HALF_SIZE = 20, /* r and s size */
wolfSSL 0:9d17e4342598 38 DSA_SIG_SIZE = 40 /* signature size */
wolfSSL 0:9d17e4342598 39 };
wolfSSL 0:9d17e4342598 40
wolfSSL 0:9d17e4342598 41
wolfSSL 0:9d17e4342598 42 #ifndef min
wolfSSL 0:9d17e4342598 43
wolfSSL 0:9d17e4342598 44 static INLINE word32 min(word32 a, word32 b)
wolfSSL 0:9d17e4342598 45 {
wolfSSL 0:9d17e4342598 46 return a > b ? b : a;
wolfSSL 0:9d17e4342598 47 }
wolfSSL 0:9d17e4342598 48
wolfSSL 0:9d17e4342598 49 #endif /* min */
wolfSSL 0:9d17e4342598 50
wolfSSL 0:9d17e4342598 51
wolfSSL 0:9d17e4342598 52 void InitDsaKey(DsaKey* key)
wolfSSL 0:9d17e4342598 53 {
wolfSSL 0:9d17e4342598 54 key->type = -1; /* haven't decided yet */
wolfSSL 0:9d17e4342598 55
wolfSSL 0:9d17e4342598 56 /* TomsFastMath doesn't use memory allocation */
wolfSSL 0:9d17e4342598 57 #ifndef USE_FAST_MATH
wolfSSL 0:9d17e4342598 58 key->p.dp = 0; /* public alloc parts */
wolfSSL 0:9d17e4342598 59 key->q.dp = 0;
wolfSSL 0:9d17e4342598 60 key->g.dp = 0;
wolfSSL 0:9d17e4342598 61 key->y.dp = 0;
wolfSSL 0:9d17e4342598 62
wolfSSL 0:9d17e4342598 63 key->x.dp = 0; /* private alloc parts */
wolfSSL 0:9d17e4342598 64 #endif
wolfSSL 0:9d17e4342598 65 }
wolfSSL 0:9d17e4342598 66
wolfSSL 0:9d17e4342598 67
wolfSSL 0:9d17e4342598 68 void FreeDsaKey(DsaKey* key)
wolfSSL 0:9d17e4342598 69 {
wolfSSL 0:9d17e4342598 70 (void)key;
wolfSSL 0:9d17e4342598 71 /* TomsFastMath doesn't use memory allocation */
wolfSSL 0:9d17e4342598 72 #ifndef USE_FAST_MATH
wolfSSL 0:9d17e4342598 73 if (key->type == DSA_PRIVATE)
wolfSSL 0:9d17e4342598 74 mp_clear(&key->x);
wolfSSL 0:9d17e4342598 75 mp_clear(&key->y);
wolfSSL 0:9d17e4342598 76 mp_clear(&key->g);
wolfSSL 0:9d17e4342598 77 mp_clear(&key->q);
wolfSSL 0:9d17e4342598 78 mp_clear(&key->p);
wolfSSL 0:9d17e4342598 79 #endif
wolfSSL 0:9d17e4342598 80 }
wolfSSL 0:9d17e4342598 81
wolfSSL 0:9d17e4342598 82
wolfSSL 0:9d17e4342598 83 int DsaSign(const byte* digest, byte* out, DsaKey* key, RNG* rng)
wolfSSL 0:9d17e4342598 84 {
wolfSSL 0:9d17e4342598 85 mp_int k, kInv, r, s, H;
wolfSSL 0:9d17e4342598 86 int ret = 0, sz;
wolfSSL 0:9d17e4342598 87 byte buffer[DSA_HALF_SIZE];
wolfSSL 0:9d17e4342598 88
wolfSSL 0:9d17e4342598 89 if (mp_init_multi(&k, &kInv, &r, &s, &H, 0) != MP_OKAY)
wolfSSL 0:9d17e4342598 90 return MP_INIT_E;
wolfSSL 0:9d17e4342598 91
wolfSSL 0:9d17e4342598 92 sz = min(sizeof(buffer), mp_unsigned_bin_size(&key->q));
wolfSSL 0:9d17e4342598 93
wolfSSL 0:9d17e4342598 94 /* generate k */
wolfSSL 0:9d17e4342598 95 RNG_GenerateBlock(rng, buffer, sz);
wolfSSL 0:9d17e4342598 96 buffer[0] |= 0x0C;
wolfSSL 0:9d17e4342598 97
wolfSSL 0:9d17e4342598 98 if (mp_read_unsigned_bin(&k, buffer, sz) != MP_OKAY)
wolfSSL 0:9d17e4342598 99 ret = MP_READ_E;
wolfSSL 0:9d17e4342598 100
wolfSSL 0:9d17e4342598 101 if (mp_cmp_d(&k, 1) != MP_GT)
wolfSSL 0:9d17e4342598 102 ret = MP_CMP_E;
wolfSSL 0:9d17e4342598 103
wolfSSL 0:9d17e4342598 104 /* inverse k mod q */
wolfSSL 0:9d17e4342598 105 if (ret == 0 && mp_invmod(&k, &key->q, &kInv) != MP_OKAY)
wolfSSL 0:9d17e4342598 106 ret = MP_INVMOD_E;
wolfSSL 0:9d17e4342598 107
wolfSSL 0:9d17e4342598 108 /* generate r, r = (g exp k mod p) mod q */
wolfSSL 0:9d17e4342598 109 if (ret == 0 && mp_exptmod(&key->g, &k, &key->p, &r) != MP_OKAY)
wolfSSL 0:9d17e4342598 110 ret = MP_EXPTMOD_E;
wolfSSL 0:9d17e4342598 111
wolfSSL 0:9d17e4342598 112 if (ret == 0 && mp_mod(&r, &key->q, &r) != MP_OKAY)
wolfSSL 0:9d17e4342598 113 ret = MP_MOD_E;
wolfSSL 0:9d17e4342598 114
wolfSSL 0:9d17e4342598 115 /* generate H from sha digest */
wolfSSL 0:9d17e4342598 116 if (ret == 0 && mp_read_unsigned_bin(&H, digest,SHA_DIGEST_SIZE) != MP_OKAY)
wolfSSL 0:9d17e4342598 117 ret = MP_READ_E;
wolfSSL 0:9d17e4342598 118
wolfSSL 0:9d17e4342598 119 /* generate s, s = (kInv * (H + x*r)) % q */
wolfSSL 0:9d17e4342598 120 if (ret == 0 && mp_mul(&key->x, &r, &s) != MP_OKAY)
wolfSSL 0:9d17e4342598 121 ret = MP_MUL_E;
wolfSSL 0:9d17e4342598 122
wolfSSL 0:9d17e4342598 123 if (ret == 0 && mp_add(&s, &H, &s) != MP_OKAY)
wolfSSL 0:9d17e4342598 124 ret = MP_ADD_E;
wolfSSL 0:9d17e4342598 125
wolfSSL 0:9d17e4342598 126 if (ret == 0 && mp_mulmod(&s, &kInv, &key->q, &s) != MP_OKAY)
wolfSSL 0:9d17e4342598 127 ret = MP_MULMOD_E;
wolfSSL 0:9d17e4342598 128
wolfSSL 0:9d17e4342598 129 /* write out */
wolfSSL 0:9d17e4342598 130 if (ret == 0) {
wolfSSL 0:9d17e4342598 131 int rSz = mp_unsigned_bin_size(&r);
wolfSSL 0:9d17e4342598 132 int sSz = mp_unsigned_bin_size(&s);
wolfSSL 0:9d17e4342598 133
wolfSSL 0:9d17e4342598 134 if (rSz == DSA_HALF_SIZE - 1) {
wolfSSL 0:9d17e4342598 135 out[0] = 0;
wolfSSL 0:9d17e4342598 136 out++;
wolfSSL 0:9d17e4342598 137 }
wolfSSL 0:9d17e4342598 138
wolfSSL 0:9d17e4342598 139 if (mp_to_unsigned_bin(&r, out) != MP_OKAY)
wolfSSL 0:9d17e4342598 140 ret = MP_TO_E;
wolfSSL 0:9d17e4342598 141 else {
wolfSSL 0:9d17e4342598 142 if (sSz == DSA_HALF_SIZE - 1) {
wolfSSL 0:9d17e4342598 143 out[rSz] = 0;
wolfSSL 0:9d17e4342598 144 out++;
wolfSSL 0:9d17e4342598 145 }
wolfSSL 0:9d17e4342598 146 ret = mp_to_unsigned_bin(&s, out + rSz);
wolfSSL 0:9d17e4342598 147 }
wolfSSL 0:9d17e4342598 148 }
wolfSSL 0:9d17e4342598 149
wolfSSL 0:9d17e4342598 150 mp_clear(&H);
wolfSSL 0:9d17e4342598 151 mp_clear(&s);
wolfSSL 0:9d17e4342598 152 mp_clear(&r);
wolfSSL 0:9d17e4342598 153 mp_clear(&kInv);
wolfSSL 0:9d17e4342598 154 mp_clear(&k);
wolfSSL 0:9d17e4342598 155
wolfSSL 0:9d17e4342598 156 return ret;
wolfSSL 0:9d17e4342598 157 }
wolfSSL 0:9d17e4342598 158
wolfSSL 0:9d17e4342598 159
wolfSSL 0:9d17e4342598 160 int DsaVerify(const byte* digest, const byte* sig, DsaKey* key, int* answer)
wolfSSL 0:9d17e4342598 161 {
wolfSSL 0:9d17e4342598 162 mp_int w, u1, u2, v, r, s;
wolfSSL 0:9d17e4342598 163 int ret = 0;
wolfSSL 0:9d17e4342598 164
wolfSSL 0:9d17e4342598 165 if (mp_init_multi(&w, &u1, &u2, &v, &r, &s) != MP_OKAY)
wolfSSL 0:9d17e4342598 166 return MP_INIT_E;
wolfSSL 0:9d17e4342598 167
wolfSSL 0:9d17e4342598 168 /* set r and s from signature */
wolfSSL 0:9d17e4342598 169 if (mp_read_unsigned_bin(&r, sig, DSA_HALF_SIZE) != MP_OKAY ||
wolfSSL 0:9d17e4342598 170 mp_read_unsigned_bin(&s, sig + DSA_HALF_SIZE, DSA_HALF_SIZE) != MP_OKAY)
wolfSSL 0:9d17e4342598 171 ret = MP_READ_E;
wolfSSL 0:9d17e4342598 172
wolfSSL 0:9d17e4342598 173 /* sanity checks */
wolfSSL 0:9d17e4342598 174
wolfSSL 0:9d17e4342598 175
wolfSSL 0:9d17e4342598 176 /* put H into u1 from sha digest */
wolfSSL 0:9d17e4342598 177 if (ret == 0 && mp_read_unsigned_bin(&u1,digest,SHA_DIGEST_SIZE) != MP_OKAY)
wolfSSL 0:9d17e4342598 178 ret = MP_READ_E;
wolfSSL 0:9d17e4342598 179
wolfSSL 0:9d17e4342598 180 /* w = s invmod q */
wolfSSL 0:9d17e4342598 181 if (ret == 0 && mp_invmod(&s, &key->q, &w) != MP_OKAY)
wolfSSL 0:9d17e4342598 182 ret = MP_INVMOD_E;
wolfSSL 0:9d17e4342598 183
wolfSSL 0:9d17e4342598 184 /* u1 = (H * w) % q */
wolfSSL 0:9d17e4342598 185 if (ret == 0 && mp_mulmod(&u1, &w, &key->q, &u1) != MP_OKAY)
wolfSSL 0:9d17e4342598 186 ret = MP_MULMOD_E;
wolfSSL 0:9d17e4342598 187
wolfSSL 0:9d17e4342598 188 /* u2 = (r * w) % q */
wolfSSL 0:9d17e4342598 189 if (ret == 0 && mp_mulmod(&r, &w, &key->q, &u2) != MP_OKAY)
wolfSSL 0:9d17e4342598 190 ret = MP_MULMOD_E;
wolfSSL 0:9d17e4342598 191
wolfSSL 0:9d17e4342598 192 /* verify v = ((g^u1 * y^u2) mod p) mod q */
wolfSSL 0:9d17e4342598 193 if (ret == 0 && mp_exptmod(&key->g, &u1, &key->p, &u1) != MP_OKAY)
wolfSSL 0:9d17e4342598 194 ret = MP_EXPTMOD_E;
wolfSSL 0:9d17e4342598 195
wolfSSL 0:9d17e4342598 196 if (ret == 0 && mp_exptmod(&key->y, &u2, &key->p, &u2) != MP_OKAY)
wolfSSL 0:9d17e4342598 197 ret = MP_EXPTMOD_E;
wolfSSL 0:9d17e4342598 198
wolfSSL 0:9d17e4342598 199 if (ret == 0 && mp_mulmod(&u1, &u2, &key->p, &v) != MP_OKAY)
wolfSSL 0:9d17e4342598 200 ret = MP_MULMOD_E;
wolfSSL 0:9d17e4342598 201
wolfSSL 0:9d17e4342598 202 if (ret == 0 && mp_mod(&v, &key->q, &v) != MP_OKAY)
wolfSSL 0:9d17e4342598 203 ret = MP_MULMOD_E;
wolfSSL 0:9d17e4342598 204
wolfSSL 0:9d17e4342598 205 /* do they match */
wolfSSL 0:9d17e4342598 206 if (ret == 0 && mp_cmp(&r, &v) == MP_EQ)
wolfSSL 0:9d17e4342598 207 *answer = 1;
wolfSSL 0:9d17e4342598 208 else
wolfSSL 0:9d17e4342598 209 *answer = 0;
wolfSSL 0:9d17e4342598 210
wolfSSL 0:9d17e4342598 211 mp_clear(&s);
wolfSSL 0:9d17e4342598 212 mp_clear(&r);
wolfSSL 0:9d17e4342598 213 mp_clear(&u1);
wolfSSL 0:9d17e4342598 214 mp_clear(&u2);
wolfSSL 0:9d17e4342598 215 mp_clear(&w);
wolfSSL 0:9d17e4342598 216 mp_clear(&v);
wolfSSL 0:9d17e4342598 217
wolfSSL 0:9d17e4342598 218 return ret;
wolfSSL 0:9d17e4342598 219 }
wolfSSL 0:9d17e4342598 220
wolfSSL 0:9d17e4342598 221
wolfSSL 0:9d17e4342598 222 #endif /* NO_DSA */
wolfSSL 0:9d17e4342598 223