1 | /* dsa.c
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2 | *
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3 | * Copyright (C) 2006-2017 wolfSSL Inc.
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4 | *
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5 | * This file is part of wolfSSL.
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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 02110-1335, USA
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20 | */
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21 |
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22 |
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23 | #ifdef HAVE_CONFIG_H
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24 | #include <config.h>
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25 | #endif
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26 |
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27 | #include <wolfssl/wolfcrypt/settings.h>
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28 |
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29 | #ifndef NO_DSA
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30 |
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31 | #include <wolfssl/wolfcrypt/random.h>
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32 | #include <wolfssl/wolfcrypt/integer.h>
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33 | #include <wolfssl/wolfcrypt/error-crypt.h>
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34 | #include <wolfssl/wolfcrypt/logging.h>
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35 | #include <wolfssl/wolfcrypt/sha.h>
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36 | #include <wolfssl/wolfcrypt/dsa.h>
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37 |
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38 | #ifdef NO_INLINE
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39 | #include <wolfssl/wolfcrypt/misc.h>
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40 | #else
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41 | #define WOLFSSL_MISC_INCLUDED
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42 | #include <wolfcrypt/src/misc.c>
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43 | #endif
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44 |
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45 |
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46 | enum {
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47 | DSA_HALF_SIZE = 20, /* r and s size */
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48 | DSA_SIG_SIZE = 40 /* signature size */
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49 | };
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50 |
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51 |
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52 |
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53 | int wc_InitDsaKey(DsaKey* key)
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54 | {
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55 | if (key == NULL)
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56 | return BAD_FUNC_ARG;
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57 |
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58 | key->type = -1; /* haven't decided yet */
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59 | key->heap = NULL;
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60 |
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61 | return mp_init_multi(
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62 | /* public alloc parts */
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63 | &key->p,
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64 | &key->q,
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65 | &key->g,
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66 | &key->y,
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67 |
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68 | /* private alloc parts */
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69 | &key->x,
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70 | NULL
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71 | );
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72 | }
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73 |
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74 |
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75 | int wc_InitDsaKey_h(DsaKey* key, void* h)
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76 | {
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77 | int ret = wc_InitDsaKey(key);
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78 | if (ret == 0)
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79 | key->heap = h;
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80 |
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81 | return ret;
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82 | }
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83 |
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84 |
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85 | void wc_FreeDsaKey(DsaKey* key)
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86 | {
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87 | if (key == NULL)
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88 | return;
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89 |
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90 | if (key->type == DSA_PRIVATE)
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91 | mp_forcezero(&key->x);
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92 |
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93 | mp_clear(&key->x);
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94 | mp_clear(&key->y);
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95 | mp_clear(&key->g);
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96 | mp_clear(&key->q);
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97 | mp_clear(&key->p);
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98 | }
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99 |
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100 | #ifdef WOLFSSL_KEY_GEN
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101 |
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102 | int wc_MakeDsaKey(WC_RNG *rng, DsaKey *dsa)
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103 | {
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104 | unsigned char *buf;
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105 | int qsize, err;
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106 |
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107 | if (rng == NULL || dsa == NULL)
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108 | return BAD_FUNC_ARG;
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109 |
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110 | qsize = mp_unsigned_bin_size(&dsa->q);
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111 | if (qsize == 0)
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112 | return BAD_FUNC_ARG;
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113 |
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114 | /* allocate ram */
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115 | buf = (unsigned char *)XMALLOC(qsize, dsa->heap,
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116 | DYNAMIC_TYPE_TMP_BUFFER);
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117 | if (buf == NULL)
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118 | return MEMORY_E;
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119 |
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120 | if (mp_init(&dsa->x) != MP_OKAY) {
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121 | XFREE(buf, dsa->heap, DYNAMIC_TYPE_TMP_BUFFER);
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122 | return MP_INIT_E;
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123 | }
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124 |
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125 | do {
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126 | /* make a random exponent mod q */
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127 | err = wc_RNG_GenerateBlock(rng, buf, qsize);
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128 | if (err != MP_OKAY) {
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129 | mp_clear(&dsa->x);
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130 | XFREE(buf, dsa->heap, DYNAMIC_TYPE_TMP_BUFFER);
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131 | return err;
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132 | }
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133 |
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134 | err = mp_read_unsigned_bin(&dsa->x, buf, qsize);
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135 | if (err != MP_OKAY) {
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136 | mp_clear(&dsa->x);
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137 | XFREE(buf, dsa->heap, DYNAMIC_TYPE_TMP_BUFFER);
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138 | return err;
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139 | }
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140 | } while (mp_cmp_d(&dsa->x, 1) != MP_GT);
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141 |
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142 | XFREE(buf, dsa->heap, DYNAMIC_TYPE_TMP_BUFFER);
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143 |
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144 | if (mp_init(&dsa->y) != MP_OKAY) {
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145 | mp_clear(&dsa->x);
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146 | return MP_INIT_E;
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147 | }
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148 |
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149 | /* public key : y = g^x mod p */
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150 | err = mp_exptmod(&dsa->g, &dsa->x, &dsa->p, &dsa->y);
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151 | if (err != MP_OKAY) {
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152 | mp_clear(&dsa->x);
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153 | mp_clear(&dsa->y);
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154 | return err;
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155 | }
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156 |
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157 | dsa->type = DSA_PRIVATE;
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158 |
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159 | return MP_OKAY;
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160 | }
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161 |
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162 | /* modulus_size in bits */
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163 | int wc_MakeDsaParameters(WC_RNG *rng, int modulus_size, DsaKey *dsa)
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164 | {
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165 | mp_int tmp, tmp2;
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166 | int err, msize, qsize,
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167 | loop_check_prime = 0,
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168 | check_prime = MP_NO;
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169 | unsigned char *buf;
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170 |
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171 | if (rng == NULL || dsa == NULL)
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172 | return BAD_FUNC_ARG;
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173 |
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174 | /* set group size in bytes from modulus size
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175 | * FIPS 186-4 defines valid values (1024, 160) (2048, 256) (3072, 256)
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176 | */
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177 | switch (modulus_size) {
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178 | case 1024:
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179 | qsize = 20;
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180 | break;
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181 | case 2048:
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182 | case 3072:
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183 | qsize = 32;
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184 | break;
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185 | default:
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186 | return BAD_FUNC_ARG;
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187 | break;
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188 | }
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189 |
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190 | /* modulus size in bytes */
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191 | msize = modulus_size / 8;
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192 |
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193 | /* allocate ram */
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194 | buf = (unsigned char *)XMALLOC(msize - qsize,
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195 | dsa->heap, DYNAMIC_TYPE_TMP_BUFFER);
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196 | if (buf == NULL) {
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197 | return MEMORY_E;
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198 | }
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199 |
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200 | /* make a random string that will be multplied against q */
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201 | err = wc_RNG_GenerateBlock(rng, buf, msize - qsize);
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202 | if (err != MP_OKAY) {
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203 | XFREE(buf, dsa->heap, DYNAMIC_TYPE_TMP_BUFFER);
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204 | return err;
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205 | }
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206 |
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207 | /* force magnitude */
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208 | buf[0] |= 0xC0;
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209 |
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210 | /* force even */
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211 | buf[msize - qsize - 1] &= ~1;
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212 |
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213 | if (mp_init_multi(&tmp2, &dsa->p, &dsa->q, 0, 0, 0) != MP_OKAY) {
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214 | mp_clear(&dsa->q);
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215 | XFREE(buf, dsa->heap, DYNAMIC_TYPE_TMP_BUFFER);
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216 | return MP_INIT_E;
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217 | }
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218 |
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219 | err = mp_read_unsigned_bin(&tmp2, buf, msize - qsize);
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220 | if (err != MP_OKAY) {
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221 | mp_clear(&dsa->q);
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222 | mp_clear(&dsa->p);
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223 | mp_clear(&tmp2);
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224 | XFREE(buf, dsa->heap, DYNAMIC_TYPE_TMP_BUFFER);
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225 | return err;
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226 | }
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227 | XFREE(buf, dsa->heap, DYNAMIC_TYPE_TMP_BUFFER);
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228 |
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229 | /* make our prime q */
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230 | err = mp_rand_prime(&dsa->q, qsize, rng, NULL);
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231 | if (err != MP_OKAY) {
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232 | mp_clear(&dsa->q);
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233 | mp_clear(&dsa->p);
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234 | mp_clear(&tmp2);
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235 | return err;
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236 | }
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237 |
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238 | /* p = random * q */
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239 | err = mp_mul(&dsa->q, &tmp2, &dsa->p);
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240 | if (err != MP_OKAY) {
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241 | mp_clear(&dsa->q);
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242 | mp_clear(&dsa->p);
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243 | mp_clear(&tmp2);
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244 | return err;
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245 | }
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246 |
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247 | /* p = random * q + 1, so q is a prime divisor of p-1 */
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248 | err = mp_add_d(&dsa->p, 1, &dsa->p);
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249 | if (err != MP_OKAY) {
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250 | mp_clear(&dsa->q);
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251 | mp_clear(&dsa->p);
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252 | mp_clear(&tmp2);
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253 | return err;
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254 | }
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255 |
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256 | if (mp_init(&tmp) != MP_OKAY) {
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257 | mp_clear(&dsa->q);
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258 | mp_clear(&dsa->p);
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259 | mp_clear(&tmp2);
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260 | return MP_INIT_E;
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261 | }
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262 |
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263 | /* tmp = 2q */
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264 | err = mp_add(&dsa->q, &dsa->q, &tmp);
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265 | if (err != MP_OKAY) {
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266 | mp_clear(&dsa->q);
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267 | mp_clear(&dsa->p);
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268 | mp_clear(&tmp);
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269 | mp_clear(&tmp2);
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270 | return err;
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271 | }
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272 |
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273 | /* loop until p is prime */
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274 | while (check_prime == MP_NO) {
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275 | err = mp_prime_is_prime(&dsa->p, 8, &check_prime);
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276 | if (err != MP_OKAY) {
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277 | mp_clear(&dsa->q);
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278 | mp_clear(&dsa->p);
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279 | mp_clear(&tmp);
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280 | mp_clear(&tmp2);
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281 | return err;
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282 | }
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283 |
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284 | if (check_prime != MP_YES) {
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285 | /* p += 2q */
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286 | err = mp_add(&tmp, &dsa->p, &dsa->p);
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287 | if (err != MP_OKAY) {
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288 | mp_clear(&dsa->q);
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289 | mp_clear(&dsa->p);
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290 | mp_clear(&tmp);
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291 | mp_clear(&tmp2);
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292 | return err;
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293 | }
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294 |
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295 | loop_check_prime++;
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296 | }
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297 | }
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298 |
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299 | /* tmp2 += (2*loop_check_prime)
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300 | * to have p = (q * tmp2) + 1 prime
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301 | */
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302 | if (loop_check_prime) {
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303 | err = mp_add_d(&tmp2, 2*loop_check_prime, &tmp2);
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304 | if (err != MP_OKAY) {
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305 | mp_clear(&dsa->q);
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306 | mp_clear(&dsa->p);
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307 | mp_clear(&tmp);
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308 | mp_clear(&tmp2);
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309 | return err;
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310 | }
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311 | }
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312 |
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313 | if (mp_init(&dsa->g) != MP_OKAY) {
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314 | mp_clear(&dsa->q);
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315 | mp_clear(&dsa->p);
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316 | mp_clear(&tmp);
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317 | mp_clear(&tmp2);
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318 | return MP_INIT_E;
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319 | }
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320 |
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321 | /* find a value g for which g^tmp2 != 1 */
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322 | if (mp_set(&dsa->g, 1) != MP_OKAY) {
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323 | mp_clear(&dsa->q);
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324 | mp_clear(&dsa->p);
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325 | mp_clear(&tmp);
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326 | mp_clear(&tmp2);
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327 | return MP_INIT_E;
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328 | }
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329 |
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330 | do {
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331 | err = mp_add_d(&dsa->g, 1, &dsa->g);
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332 | if (err != MP_OKAY) {
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333 | mp_clear(&dsa->q);
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334 | mp_clear(&dsa->p);
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335 | mp_clear(&dsa->g);
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336 | mp_clear(&tmp);
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337 | mp_clear(&tmp2);
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338 | return err;
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339 | }
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340 |
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341 | err = mp_exptmod(&dsa->g, &tmp2, &dsa->p, &tmp);
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342 | if (err != MP_OKAY) {
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343 | mp_clear(&dsa->q);
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344 | mp_clear(&dsa->p);
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345 | mp_clear(&dsa->g);
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346 | mp_clear(&tmp);
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347 | mp_clear(&tmp2);
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348 | return err;
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349 | }
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350 |
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351 | } while (mp_cmp_d(&tmp, 1) == MP_EQ);
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352 |
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353 | /* at this point tmp generates a group of order q mod p */
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354 | mp_exch(&tmp, &dsa->g);
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355 |
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356 | mp_clear(&tmp);
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357 | mp_clear(&tmp2);
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358 |
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359 | return MP_OKAY;
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360 | }
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361 | #endif /* WOLFSSL_KEY_GEN */
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362 |
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363 |
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364 | int wc_DsaSign(const byte* digest, byte* out, DsaKey* key, WC_RNG* rng)
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365 | {
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366 | mp_int k, kInv, r, s, H;
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367 | int ret, sz;
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368 | byte buffer[DSA_HALF_SIZE];
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369 | byte* tmp; /* initial output pointer */
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370 |
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371 | if (digest == NULL || out == NULL || key == NULL || rng == NULL) {
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372 | return BAD_FUNC_ARG;
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373 | }
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374 |
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375 | tmp = out;
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376 |
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377 | sz = min((int)sizeof(buffer), mp_unsigned_bin_size(&key->q));
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378 |
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379 | if (mp_init_multi(&k, &kInv, &r, &s, &H, 0) != MP_OKAY)
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380 | return MP_INIT_E;
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381 |
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382 | do {
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383 | /* generate k */
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384 | ret = wc_RNG_GenerateBlock(rng, buffer, sz);
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385 | if (ret != 0)
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386 | return ret;
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387 |
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388 | buffer[0] |= 0x0C;
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389 |
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390 | if (mp_read_unsigned_bin(&k, buffer, sz) != MP_OKAY)
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391 | ret = MP_READ_E;
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392 |
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393 | /* k is a random numnber and it should be less than q
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394 | * if k greater than repeat
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395 | */
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396 | } while (mp_cmp(&k, &key->q) != MP_LT);
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397 |
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398 | if (ret == 0 && mp_cmp_d(&k, 1) != MP_GT)
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399 | ret = MP_CMP_E;
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400 |
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401 | /* inverse k mod q */
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402 | if (ret == 0 && mp_invmod(&k, &key->q, &kInv) != MP_OKAY)
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403 | ret = MP_INVMOD_E;
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404 |
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405 | /* generate r, r = (g exp k mod p) mod q */
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406 | if (ret == 0 && mp_exptmod(&key->g, &k, &key->p, &r) != MP_OKAY)
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407 | ret = MP_EXPTMOD_E;
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408 |
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409 | if (ret == 0 && mp_mod(&r, &key->q, &r) != MP_OKAY)
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410 | ret = MP_MOD_E;
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411 |
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412 | /* generate H from sha digest */
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413 | if (ret == 0 && mp_read_unsigned_bin(&H, digest,WC_SHA_DIGEST_SIZE) != MP_OKAY)
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414 | ret = MP_READ_E;
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415 |
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416 | /* generate s, s = (kInv * (H + x*r)) % q */
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417 | if (ret == 0 && mp_mul(&key->x, &r, &s) != MP_OKAY)
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418 | ret = MP_MUL_E;
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419 |
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420 | if (ret == 0 && mp_add(&s, &H, &s) != MP_OKAY)
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421 | ret = MP_ADD_E;
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422 |
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423 | if (ret == 0 && mp_mulmod(&s, &kInv, &key->q, &s) != MP_OKAY)
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424 | ret = MP_MULMOD_E;
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425 |
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426 | /* detect zero r or s */
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427 | if (ret == 0 && (mp_iszero(&r) == MP_YES || mp_iszero(&s) == MP_YES))
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428 | ret = MP_ZERO_E;
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429 |
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430 | /* write out */
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431 | if (ret == 0) {
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432 | int rSz = mp_unsigned_bin_size(&r);
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433 | int sSz = mp_unsigned_bin_size(&s);
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434 |
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435 | while (rSz++ < DSA_HALF_SIZE) {
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436 | *out++ = 0x00; /* pad front with zeros */
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437 | }
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438 |
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439 | if (mp_to_unsigned_bin(&r, out) != MP_OKAY)
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440 | ret = MP_TO_E;
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441 | else {
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442 | out = tmp + DSA_HALF_SIZE; /* advance to s in output */
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443 | while (sSz++ < DSA_HALF_SIZE) {
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444 | *out++ = 0x00; /* pad front with zeros */
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445 | }
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446 | ret = mp_to_unsigned_bin(&s, out);
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447 | }
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448 | }
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449 |
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450 | mp_clear(&H);
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451 | mp_clear(&s);
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452 | mp_clear(&r);
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453 | mp_clear(&kInv);
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454 | mp_clear(&k);
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455 |
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456 | return ret;
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457 | }
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458 |
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459 |
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460 | int wc_DsaVerify(const byte* digest, const byte* sig, DsaKey* key, int* answer)
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461 | {
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462 | mp_int w, u1, u2, v, r, s;
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463 | int ret = 0;
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464 |
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465 | if (digest == NULL || sig == NULL || key == NULL || answer == NULL) {
|
---|
466 | return BAD_FUNC_ARG;
|
---|
467 | }
|
---|
468 |
|
---|
469 | if (mp_init_multi(&w, &u1, &u2, &v, &r, &s) != MP_OKAY)
|
---|
470 | return MP_INIT_E;
|
---|
471 |
|
---|
472 | /* set r and s from signature */
|
---|
473 | if (mp_read_unsigned_bin(&r, sig, DSA_HALF_SIZE) != MP_OKAY ||
|
---|
474 | mp_read_unsigned_bin(&s, sig + DSA_HALF_SIZE, DSA_HALF_SIZE) != MP_OKAY)
|
---|
475 | ret = MP_READ_E;
|
---|
476 |
|
---|
477 | /* sanity checks */
|
---|
478 | if (ret == 0) {
|
---|
479 | if (mp_iszero(&r) == MP_YES || mp_iszero(&s) == MP_YES ||
|
---|
480 | mp_cmp(&r, &key->q) != MP_LT || mp_cmp(&s, &key->q) != MP_LT) {
|
---|
481 | ret = MP_ZERO_E;
|
---|
482 | }
|
---|
483 | }
|
---|
484 |
|
---|
485 | /* put H into u1 from sha digest */
|
---|
486 | if (ret == 0 && mp_read_unsigned_bin(&u1,digest,WC_SHA_DIGEST_SIZE) != MP_OKAY)
|
---|
487 | ret = MP_READ_E;
|
---|
488 |
|
---|
489 | /* w = s invmod q */
|
---|
490 | if (ret == 0 && mp_invmod(&s, &key->q, &w) != MP_OKAY)
|
---|
491 | ret = MP_INVMOD_E;
|
---|
492 |
|
---|
493 | /* u1 = (H * w) % q */
|
---|
494 | if (ret == 0 && mp_mulmod(&u1, &w, &key->q, &u1) != MP_OKAY)
|
---|
495 | ret = MP_MULMOD_E;
|
---|
496 |
|
---|
497 | /* u2 = (r * w) % q */
|
---|
498 | if (ret == 0 && mp_mulmod(&r, &w, &key->q, &u2) != MP_OKAY)
|
---|
499 | ret = MP_MULMOD_E;
|
---|
500 |
|
---|
501 | /* verify v = ((g^u1 * y^u2) mod p) mod q */
|
---|
502 | if (ret == 0 && mp_exptmod(&key->g, &u1, &key->p, &u1) != MP_OKAY)
|
---|
503 | ret = MP_EXPTMOD_E;
|
---|
504 |
|
---|
505 | if (ret == 0 && mp_exptmod(&key->y, &u2, &key->p, &u2) != MP_OKAY)
|
---|
506 | ret = MP_EXPTMOD_E;
|
---|
507 |
|
---|
508 | if (ret == 0 && mp_mulmod(&u1, &u2, &key->p, &v) != MP_OKAY)
|
---|
509 | ret = MP_MULMOD_E;
|
---|
510 |
|
---|
511 | if (ret == 0 && mp_mod(&v, &key->q, &v) != MP_OKAY)
|
---|
512 | ret = MP_MULMOD_E;
|
---|
513 |
|
---|
514 | /* do they match */
|
---|
515 | if (ret == 0 && mp_cmp(&r, &v) == MP_EQ)
|
---|
516 | *answer = 1;
|
---|
517 | else
|
---|
518 | *answer = 0;
|
---|
519 |
|
---|
520 | mp_clear(&s);
|
---|
521 | mp_clear(&r);
|
---|
522 | mp_clear(&u1);
|
---|
523 | mp_clear(&u2);
|
---|
524 | mp_clear(&w);
|
---|
525 | mp_clear(&v);
|
---|
526 |
|
---|
527 | return ret;
|
---|
528 | }
|
---|
529 |
|
---|
530 |
|
---|
531 | #endif /* NO_DSA */
|
---|
532 |
|
---|