[164] | 1 | /* dsa.c
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| 2 | *
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| 3 | * Copyright (C) 2006-2015 wolfSSL Inc.
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| 4 | *
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| 5 | * This file is part of wolfSSL. (formerly known as CyaSSL)
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| 6 | *
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| 7 | * wolfSSL is free software; you can redistribute it and/or modify
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| 8 | * it under the terms of the GNU General Public License as published by
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| 9 | * the Free Software Foundation; either version 2 of the License, or
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| 10 | * (at your option) any later version.
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| 11 | *
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| 12 | * wolfSSL is distributed in the hope that it will be useful,
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| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 15 | * GNU General Public License for more details.
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| 16 | *
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| 17 | * You should have received a copy of the GNU General Public License
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| 18 | * along with this program; if not, write to the Free Software
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| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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| 20 | */
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| 21 |
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| 22 | #ifdef HAVE_CONFIG_H
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| 23 | #include <config.h>
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| 24 | #endif
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| 25 |
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| 26 | #include <wolfssl/wolfcrypt/settings.h>
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| 27 |
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| 28 | #ifndef NO_DSA
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| 29 |
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| 30 | #include <wolfssl/wolfcrypt/random.h>
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| 31 | #include <wolfssl/wolfcrypt/integer.h>
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| 32 | #include <wolfssl/wolfcrypt/error-crypt.h>
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| 33 | #include <wolfssl/wolfcrypt/logging.h>
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| 34 | #include <wolfssl/wolfcrypt/sha.h>
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| 35 | #include <wolfssl/wolfcrypt/dsa.h>
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| 36 |
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| 37 |
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| 38 | enum {
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| 39 | DSA_HALF_SIZE = 20, /* r and s size */
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| 40 | DSA_SIG_SIZE = 40 /* signature size */
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| 41 | };
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| 42 |
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| 43 |
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| 44 | #ifdef min
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| 45 | #define WOLFSSL_HAVE_MIN
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| 46 | #endif
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| 47 | #ifndef WOLFSSL_HAVE_MIN
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| 48 | #define WOLFSSL_HAVE_MIN
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| 49 |
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| 50 | static INLINE word32 min(word32 a, word32 b)
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| 51 | {
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| 52 | return a > b ? b : a;
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| 53 | }
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| 54 |
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| 55 | #endif /* WOLFSSL_HAVE_MIN */
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| 56 |
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| 57 |
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| 58 | void wc_InitDsaKey(DsaKey* key)
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| 59 | {
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| 60 | key->type = -1; /* haven't decided yet */
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| 61 |
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| 62 | /* TomsFastMath doesn't use memory allocation */
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| 63 | #ifndef USE_FAST_MATH
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| 64 | key->p.dp = 0; /* public alloc parts */
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| 65 | key->q.dp = 0;
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| 66 | key->g.dp = 0;
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| 67 | key->y.dp = 0;
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| 68 |
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| 69 | key->x.dp = 0; /* private alloc parts */
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| 70 | #endif
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| 71 | }
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| 72 |
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| 73 |
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| 74 | void wc_FreeDsaKey(DsaKey* key)
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| 75 | {
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| 76 | (void)key;
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| 77 | /* TomsFastMath doesn't use memory allocation */
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| 78 | #ifndef USE_FAST_MATH
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| 79 | if (key->type == DSA_PRIVATE)
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| 80 | mp_clear(&key->x);
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| 81 | mp_clear(&key->y);
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| 82 | mp_clear(&key->g);
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| 83 | mp_clear(&key->q);
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| 84 | mp_clear(&key->p);
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| 85 | #endif
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| 86 | }
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| 87 |
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| 88 | #ifdef WOLFSSL_KEY_GEN
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| 89 |
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| 90 | int wc_MakeDsaKey(WC_RNG *rng, DsaKey *dsa)
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| 91 | {
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| 92 | unsigned char *buf;
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| 93 | int qsize, err;
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| 94 |
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| 95 | if (rng == NULL || dsa == NULL)
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| 96 | return BAD_FUNC_ARG;
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| 97 |
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| 98 | qsize = mp_unsigned_bin_size(&dsa->q);
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| 99 | if (qsize == 0)
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| 100 | return BAD_FUNC_ARG;
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| 101 |
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| 102 | /* allocate ram */
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| 103 | buf = (unsigned char *)XMALLOC(qsize, NULL,
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| 104 | DYNAMIC_TYPE_TMP_BUFFER);
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| 105 | if (buf == NULL)
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| 106 | return MEMORY_E;
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| 107 |
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| 108 | if (mp_init(&dsa->x) != MP_OKAY) {
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| 109 | XFREE(buf, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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| 110 | return MP_INIT_E;
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| 111 | }
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| 112 |
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| 113 | do {
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| 114 | /* make a random exponent mod q */
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| 115 | err = wc_RNG_GenerateBlock(rng, buf, qsize);
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| 116 | if (err != MP_OKAY) {
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| 117 | mp_clear(&dsa->x);
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| 118 | XFREE(buf, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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| 119 | return err;
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| 120 | }
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| 121 |
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| 122 | err = mp_read_unsigned_bin(&dsa->x, buf, qsize);
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| 123 | if (err != MP_OKAY) {
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| 124 | mp_clear(&dsa->x);
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| 125 | XFREE(buf, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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| 126 | return err;
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| 127 | }
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| 128 | } while (mp_cmp_d(&dsa->x, 1) != MP_GT);
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| 129 |
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| 130 | XFREE(buf, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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| 131 |
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| 132 | if (mp_init(&dsa->y) != MP_OKAY) {
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| 133 | mp_clear(&dsa->x);
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| 134 | return MP_INIT_E;
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| 135 | }
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| 136 |
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| 137 | /* public key : y = g^x mod p */
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| 138 | err = mp_exptmod(&dsa->g, &dsa->x, &dsa->p, &dsa->y);
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| 139 | if (err != MP_OKAY) {
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| 140 | mp_clear(&dsa->x);
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| 141 | mp_clear(&dsa->y);
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| 142 | return err;
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| 143 | }
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| 144 |
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| 145 | dsa->type = DSA_PRIVATE;
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| 146 |
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| 147 | return MP_OKAY;
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| 148 | }
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| 149 |
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| 150 | /* modulus_size in bits */
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| 151 | int wc_MakeDsaParameters(WC_RNG *rng, int modulus_size, DsaKey *dsa)
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| 152 | {
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| 153 | mp_int tmp, tmp2;
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| 154 | int err, msize, qsize,
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| 155 | loop_check_prime = 0,
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| 156 | check_prime = MP_NO;
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| 157 | unsigned char *buf;
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| 158 |
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| 159 | if (rng == NULL || dsa == NULL)
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| 160 | return BAD_FUNC_ARG;
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| 161 |
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| 162 | /* set group size in bytes from modulus size
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| 163 | * FIPS 186-4 defines valid values (1024, 160) (2048, 256) (3072, 256)
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| 164 | */
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| 165 | switch (modulus_size) {
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| 166 | case 1024:
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| 167 | qsize = 20;
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| 168 | break;
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| 169 | case 2048:
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| 170 | case 3072:
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| 171 | qsize = 32;
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| 172 | break;
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| 173 | default:
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| 174 | return BAD_FUNC_ARG;
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| 175 | break;
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| 176 | }
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| 177 |
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| 178 | /* modulus size in bytes */
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| 179 | msize = modulus_size / 8;
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| 180 |
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| 181 | /* allocate ram */
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| 182 | buf = (unsigned char *)XMALLOC(msize - qsize,
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| 183 | NULL, DYNAMIC_TYPE_TMP_BUFFER);
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| 184 | if (buf == NULL) {
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| 185 | return MEMORY_E;
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| 186 | }
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| 187 |
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| 188 | /* make a random string that will be multplied against q */
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| 189 | err = wc_RNG_GenerateBlock(rng, buf, msize - qsize);
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| 190 | if (err != MP_OKAY) {
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| 191 | XFREE(buf, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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| 192 | return err;
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| 193 | }
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| 194 |
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| 195 | /* force magnitude */
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| 196 | buf[0] |= 0xC0;
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| 197 |
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| 198 | /* force even */
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| 199 | buf[msize - qsize - 1] &= ~1;
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| 200 |
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| 201 | if (mp_init_multi(&tmp2, &dsa->p, &dsa->q, 0, 0, 0) != MP_OKAY) {
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| 202 | mp_clear(&dsa->q);
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| 203 | XFREE(buf, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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| 204 | return MP_INIT_E;
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| 205 | }
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| 206 |
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| 207 | err = mp_read_unsigned_bin(&tmp2, buf, msize - qsize);
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| 208 | if (err != MP_OKAY) {
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| 209 | mp_clear(&dsa->q);
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| 210 | mp_clear(&dsa->p);
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| 211 | mp_clear(&tmp2);
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| 212 | XFREE(buf, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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| 213 | return err;
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| 214 | }
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| 215 | XFREE(buf, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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| 216 |
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| 217 | /* make our prime q */
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| 218 | err = mp_rand_prime(&dsa->q, qsize, rng, NULL);
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| 219 | if (err != MP_OKAY) {
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| 220 | mp_clear(&dsa->q);
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| 221 | mp_clear(&dsa->p);
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| 222 | mp_clear(&tmp2);
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| 223 | return err;
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| 224 | }
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| 225 |
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| 226 | /* p = random * q */
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| 227 | err = mp_mul(&dsa->q, &tmp2, &dsa->p);
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| 228 | if (err != MP_OKAY) {
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| 229 | mp_clear(&dsa->q);
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| 230 | mp_clear(&dsa->p);
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| 231 | mp_clear(&tmp2);
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| 232 | return err;
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| 233 | }
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| 234 |
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| 235 | /* p = random * q + 1, so q is a prime divisor of p-1 */
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| 236 | err = mp_add_d(&dsa->p, 1, &dsa->p);
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| 237 | if (err != MP_OKAY) {
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| 238 | mp_clear(&dsa->q);
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| 239 | mp_clear(&dsa->p);
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| 240 | mp_clear(&tmp2);
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| 241 | return err;
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| 242 | }
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| 243 |
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| 244 | if (mp_init(&tmp) != MP_OKAY) {
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| 245 | mp_clear(&dsa->q);
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| 246 | mp_clear(&dsa->p);
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| 247 | mp_clear(&tmp2);
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| 248 | return MP_INIT_E;
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| 249 | }
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| 250 |
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| 251 | /* tmp = 2q */
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| 252 | err = mp_add(&dsa->q, &dsa->q, &tmp);
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| 253 | if (err != MP_OKAY) {
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| 254 | mp_clear(&dsa->q);
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| 255 | mp_clear(&dsa->p);
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| 256 | mp_clear(&tmp);
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| 257 | mp_clear(&tmp2);
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| 258 | return err;
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| 259 | }
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| 260 |
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| 261 | /* loop until p is prime */
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| 262 | while (check_prime == MP_NO) {
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| 263 | err = mp_prime_is_prime(&dsa->p, 8, &check_prime);
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| 264 | if (err != MP_OKAY) {
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| 265 | mp_clear(&dsa->q);
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| 266 | mp_clear(&dsa->p);
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| 267 | mp_clear(&tmp);
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| 268 | mp_clear(&tmp2);
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| 269 | return err;
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| 270 | }
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| 271 |
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| 272 | if (check_prime != MP_YES) {
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| 273 | /* p += 2q */
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| 274 | err = mp_add(&tmp, &dsa->p, &dsa->p);
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| 275 | if (err != MP_OKAY) {
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| 276 | mp_clear(&dsa->q);
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| 277 | mp_clear(&dsa->p);
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| 278 | mp_clear(&tmp);
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| 279 | mp_clear(&tmp2);
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| 280 | return err;
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| 281 | }
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| 282 |
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| 283 | loop_check_prime++;
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| 284 | }
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| 285 | }
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| 286 |
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| 287 | /* tmp2 += (2*loop_check_prime)
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| 288 | * to have p = (q * tmp2) + 1 prime
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| 289 | */
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| 290 | if (loop_check_prime) {
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| 291 | err = mp_add_d(&tmp2, 2*loop_check_prime, &tmp2);
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| 292 | if (err != MP_OKAY) {
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| 293 | mp_clear(&dsa->q);
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| 294 | mp_clear(&dsa->p);
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| 295 | mp_clear(&tmp);
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| 296 | mp_clear(&tmp2);
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| 297 | return err;
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| 298 | }
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| 299 | }
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| 300 |
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| 301 | if (mp_init(&dsa->g) != MP_OKAY) {
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| 302 | mp_clear(&dsa->q);
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| 303 | mp_clear(&dsa->p);
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| 304 | mp_clear(&tmp);
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| 305 | mp_clear(&tmp2);
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| 306 | return MP_INIT_E;
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| 307 | }
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| 308 |
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| 309 | /* find a value g for which g^tmp2 != 1 */
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| 310 | mp_set(&dsa->g, 1);
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| 311 |
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| 312 | do {
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| 313 | err = mp_add_d(&dsa->g, 1, &dsa->g);
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| 314 | if (err != MP_OKAY) {
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| 315 | mp_clear(&dsa->q);
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| 316 | mp_clear(&dsa->p);
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| 317 | mp_clear(&dsa->g);
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| 318 | mp_clear(&tmp);
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| 319 | mp_clear(&tmp2);
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| 320 | return err;
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| 321 | }
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| 322 |
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| 323 | err = mp_exptmod(&dsa->g, &tmp2, &dsa->p, &tmp);
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| 324 | if (err != MP_OKAY) {
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| 325 | mp_clear(&dsa->q);
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| 326 | mp_clear(&dsa->p);
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| 327 | mp_clear(&dsa->g);
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| 328 | mp_clear(&tmp);
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| 329 | mp_clear(&tmp2);
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| 330 | return err;
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| 331 | }
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| 332 |
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| 333 | } while (mp_cmp_d(&tmp, 1) == MP_EQ);
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| 334 |
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| 335 | /* at this point tmp generates a group of order q mod p */
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| 336 | mp_exch(&tmp, &dsa->g);
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| 337 |
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| 338 | mp_clear(&tmp);
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| 339 | mp_clear(&tmp2);
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| 340 |
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| 341 | return MP_OKAY;
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| 342 | }
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| 343 | #endif /* WOLFSSL_KEY_GEN */
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| 344 |
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| 345 |
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| 346 | int wc_DsaSign(const byte* digest, byte* out, DsaKey* key, WC_RNG* rng)
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| 347 | {
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| 348 | mp_int k, kInv, r, s, H;
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| 349 | int ret, sz;
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| 350 | byte buffer[DSA_HALF_SIZE];
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| 351 |
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| 352 | sz = min(sizeof(buffer), mp_unsigned_bin_size(&key->q));
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| 353 |
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| 354 | /* generate k */
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| 355 | ret = wc_RNG_GenerateBlock(rng, buffer, sz);
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| 356 | if (ret != 0)
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| 357 | return ret;
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| 358 |
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| 359 | buffer[0] |= 0x0C;
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| 360 |
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| 361 | if (mp_init_multi(&k, &kInv, &r, &s, &H, 0) != MP_OKAY)
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| 362 | return MP_INIT_E;
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| 363 |
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| 364 | if (mp_read_unsigned_bin(&k, buffer, sz) != MP_OKAY)
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| 365 | ret = MP_READ_E;
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| 366 |
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| 367 | if (ret == 0 && mp_cmp_d(&k, 1) != MP_GT)
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| 368 | ret = MP_CMP_E;
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| 369 |
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| 370 | /* inverse k mod q */
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| 371 | if (ret == 0 && mp_invmod(&k, &key->q, &kInv) != MP_OKAY)
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| 372 | ret = MP_INVMOD_E;
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| 373 |
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| 374 | /* generate r, r = (g exp k mod p) mod q */
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| 375 | if (ret == 0 && mp_exptmod(&key->g, &k, &key->p, &r) != MP_OKAY)
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| 376 | ret = MP_EXPTMOD_E;
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| 377 |
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| 378 | if (ret == 0 && mp_mod(&r, &key->q, &r) != MP_OKAY)
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| 379 | ret = MP_MOD_E;
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| 380 |
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| 381 | /* generate H from sha digest */
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| 382 | if (ret == 0 && mp_read_unsigned_bin(&H, digest,SHA_DIGEST_SIZE) != MP_OKAY)
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| 383 | ret = MP_READ_E;
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| 384 |
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| 385 | /* generate s, s = (kInv * (H + x*r)) % q */
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| 386 | if (ret == 0 && mp_mul(&key->x, &r, &s) != MP_OKAY)
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| 387 | ret = MP_MUL_E;
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| 388 |
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| 389 | if (ret == 0 && mp_add(&s, &H, &s) != MP_OKAY)
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| 390 | ret = MP_ADD_E;
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| 391 |
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| 392 | if (ret == 0 && mp_mulmod(&s, &kInv, &key->q, &s) != MP_OKAY)
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| 393 | ret = MP_MULMOD_E;
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| 394 |
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| 395 | /* write out */
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| 396 | if (ret == 0) {
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| 397 | int rSz = mp_unsigned_bin_size(&r);
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| 398 | int sSz = mp_unsigned_bin_size(&s);
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| 399 |
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| 400 | if (rSz == DSA_HALF_SIZE - 1) {
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| 401 | out[0] = 0;
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| 402 | out++;
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| 403 | }
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| 404 |
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| 405 | if (mp_to_unsigned_bin(&r, out) != MP_OKAY)
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| 406 | ret = MP_TO_E;
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| 407 | else {
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| 408 | if (sSz == DSA_HALF_SIZE - 1) {
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| 409 | out[rSz] = 0;
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| 410 | out++;
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| 411 | }
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| 412 | ret = mp_to_unsigned_bin(&s, out + rSz);
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| 413 | }
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| 414 | }
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| 415 |
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| 416 | mp_clear(&H);
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| 417 | mp_clear(&s);
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| 418 | mp_clear(&r);
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| 419 | mp_clear(&kInv);
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| 420 | mp_clear(&k);
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| 421 |
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| 422 | return ret;
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| 423 | }
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| 424 |
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| 425 |
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| 426 | int wc_DsaVerify(const byte* digest, const byte* sig, DsaKey* key, int* answer)
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| 427 | {
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| 428 | mp_int w, u1, u2, v, r, s;
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| 429 | int ret = 0;
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| 430 |
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| 431 | if (mp_init_multi(&w, &u1, &u2, &v, &r, &s) != MP_OKAY)
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| 432 | return MP_INIT_E;
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| 433 |
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| 434 | /* set r and s from signature */
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| 435 | if (mp_read_unsigned_bin(&r, sig, DSA_HALF_SIZE) != MP_OKAY ||
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| 436 | mp_read_unsigned_bin(&s, sig + DSA_HALF_SIZE, DSA_HALF_SIZE) != MP_OKAY)
|
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| 437 | ret = MP_READ_E;
|
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| 438 |
|
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| 439 | /* sanity checks */
|
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| 440 | if (ret == 0) {
|
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| 441 | if (mp_iszero(&r) == MP_YES || mp_iszero(&s) == MP_YES ||
|
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| 442 | mp_cmp(&r, &key->q) != MP_LT || mp_cmp(&s, &key->q) != MP_LT) {
|
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| 443 | ret = MP_ZERO_E;
|
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| 444 | }
|
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| 445 | }
|
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| 446 |
|
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| 447 | /* put H into u1 from sha digest */
|
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| 448 | if (ret == 0 && mp_read_unsigned_bin(&u1,digest,SHA_DIGEST_SIZE) != MP_OKAY)
|
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| 449 | ret = MP_READ_E;
|
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| 450 |
|
---|
| 451 | /* w = s invmod q */
|
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| 452 | if (ret == 0 && mp_invmod(&s, &key->q, &w) != MP_OKAY)
|
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| 453 | ret = MP_INVMOD_E;
|
---|
| 454 |
|
---|
| 455 | /* u1 = (H * w) % q */
|
---|
| 456 | if (ret == 0 && mp_mulmod(&u1, &w, &key->q, &u1) != MP_OKAY)
|
---|
| 457 | ret = MP_MULMOD_E;
|
---|
| 458 |
|
---|
| 459 | /* u2 = (r * w) % q */
|
---|
| 460 | if (ret == 0 && mp_mulmod(&r, &w, &key->q, &u2) != MP_OKAY)
|
---|
| 461 | ret = MP_MULMOD_E;
|
---|
| 462 |
|
---|
| 463 | /* verify v = ((g^u1 * y^u2) mod p) mod q */
|
---|
| 464 | if (ret == 0 && mp_exptmod(&key->g, &u1, &key->p, &u1) != MP_OKAY)
|
---|
| 465 | ret = MP_EXPTMOD_E;
|
---|
| 466 |
|
---|
| 467 | if (ret == 0 && mp_exptmod(&key->y, &u2, &key->p, &u2) != MP_OKAY)
|
---|
| 468 | ret = MP_EXPTMOD_E;
|
---|
| 469 |
|
---|
| 470 | if (ret == 0 && mp_mulmod(&u1, &u2, &key->p, &v) != MP_OKAY)
|
---|
| 471 | ret = MP_MULMOD_E;
|
---|
| 472 |
|
---|
| 473 | if (ret == 0 && mp_mod(&v, &key->q, &v) != MP_OKAY)
|
---|
| 474 | ret = MP_MULMOD_E;
|
---|
| 475 |
|
---|
| 476 | /* do they match */
|
---|
| 477 | if (ret == 0 && mp_cmp(&r, &v) == MP_EQ)
|
---|
| 478 | *answer = 1;
|
---|
| 479 | else
|
---|
| 480 | *answer = 0;
|
---|
| 481 |
|
---|
| 482 | mp_clear(&s);
|
---|
| 483 | mp_clear(&r);
|
---|
| 484 | mp_clear(&u1);
|
---|
| 485 | mp_clear(&u2);
|
---|
| 486 | mp_clear(&w);
|
---|
| 487 | mp_clear(&v);
|
---|
| 488 |
|
---|
| 489 | return ret;
|
---|
| 490 | }
|
---|
| 491 |
|
---|
| 492 |
|
---|
| 493 | #endif /* NO_DSA */
|
---|
| 494 |
|
---|