1 | /*
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2 | * Copyright 2001-2021 The OpenSSL Project Authors. All Rights Reserved.
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3 | * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
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4 | *
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5 | * Licensed under the Apache License 2.0 (the "License"). You may not use
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6 | * this file except in compliance with the License. You can obtain a copy
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7 | * in the file LICENSE in the source distribution or at
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8 | * https://www.openssl.org/source/license.html
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9 | */
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10 |
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11 | /*
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12 | * ECDSA low level APIs are deprecated for public use, but still ok for
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13 | * internal use.
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14 | */
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15 | #include "internal/deprecated.h"
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16 |
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17 | #include <openssl/err.h>
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18 |
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19 | #include "ec_local.h"
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20 |
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21 | const EC_METHOD *EC_GFp_mont_method(void)
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22 | {
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23 | static const EC_METHOD ret = {
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24 | EC_FLAGS_DEFAULT_OCT,
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25 | NID_X9_62_prime_field,
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26 | ossl_ec_GFp_mont_group_init,
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27 | ossl_ec_GFp_mont_group_finish,
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28 | ossl_ec_GFp_mont_group_clear_finish,
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29 | ossl_ec_GFp_mont_group_copy,
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30 | ossl_ec_GFp_mont_group_set_curve,
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31 | ossl_ec_GFp_simple_group_get_curve,
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32 | ossl_ec_GFp_simple_group_get_degree,
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33 | ossl_ec_group_simple_order_bits,
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34 | ossl_ec_GFp_simple_group_check_discriminant,
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35 | ossl_ec_GFp_simple_point_init,
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36 | ossl_ec_GFp_simple_point_finish,
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37 | ossl_ec_GFp_simple_point_clear_finish,
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38 | ossl_ec_GFp_simple_point_copy,
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39 | ossl_ec_GFp_simple_point_set_to_infinity,
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40 | ossl_ec_GFp_simple_point_set_affine_coordinates,
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41 | ossl_ec_GFp_simple_point_get_affine_coordinates,
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42 | 0, 0, 0,
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43 | ossl_ec_GFp_simple_add,
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44 | ossl_ec_GFp_simple_dbl,
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45 | ossl_ec_GFp_simple_invert,
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46 | ossl_ec_GFp_simple_is_at_infinity,
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47 | ossl_ec_GFp_simple_is_on_curve,
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48 | ossl_ec_GFp_simple_cmp,
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49 | ossl_ec_GFp_simple_make_affine,
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50 | ossl_ec_GFp_simple_points_make_affine,
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51 | 0 /* mul */ ,
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52 | 0 /* precompute_mult */ ,
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53 | 0 /* have_precompute_mult */ ,
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54 | ossl_ec_GFp_mont_field_mul,
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55 | ossl_ec_GFp_mont_field_sqr,
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56 | 0 /* field_div */ ,
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57 | ossl_ec_GFp_mont_field_inv,
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58 | ossl_ec_GFp_mont_field_encode,
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59 | ossl_ec_GFp_mont_field_decode,
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60 | ossl_ec_GFp_mont_field_set_to_one,
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61 | ossl_ec_key_simple_priv2oct,
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62 | ossl_ec_key_simple_oct2priv,
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63 | 0, /* set private */
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64 | ossl_ec_key_simple_generate_key,
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65 | ossl_ec_key_simple_check_key,
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66 | ossl_ec_key_simple_generate_public_key,
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67 | 0, /* keycopy */
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68 | 0, /* keyfinish */
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69 | ossl_ecdh_simple_compute_key,
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70 | ossl_ecdsa_simple_sign_setup,
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71 | ossl_ecdsa_simple_sign_sig,
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72 | ossl_ecdsa_simple_verify_sig,
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73 | 0, /* field_inverse_mod_ord */
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74 | ossl_ec_GFp_simple_blind_coordinates,
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75 | ossl_ec_GFp_simple_ladder_pre,
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76 | ossl_ec_GFp_simple_ladder_step,
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77 | ossl_ec_GFp_simple_ladder_post
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78 | };
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79 |
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80 | return &ret;
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81 | }
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82 |
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83 | int ossl_ec_GFp_mont_group_init(EC_GROUP *group)
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84 | {
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85 | int ok;
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86 |
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87 | ok = ossl_ec_GFp_simple_group_init(group);
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88 | group->field_data1 = NULL;
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89 | group->field_data2 = NULL;
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90 | return ok;
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91 | }
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92 |
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93 | void ossl_ec_GFp_mont_group_finish(EC_GROUP *group)
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94 | {
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95 | BN_MONT_CTX_free(group->field_data1);
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96 | group->field_data1 = NULL;
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97 | BN_free(group->field_data2);
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98 | group->field_data2 = NULL;
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99 | ossl_ec_GFp_simple_group_finish(group);
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100 | }
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101 |
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102 | void ossl_ec_GFp_mont_group_clear_finish(EC_GROUP *group)
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103 | {
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104 | BN_MONT_CTX_free(group->field_data1);
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105 | group->field_data1 = NULL;
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106 | BN_clear_free(group->field_data2);
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107 | group->field_data2 = NULL;
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108 | ossl_ec_GFp_simple_group_clear_finish(group);
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109 | }
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110 |
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111 | int ossl_ec_GFp_mont_group_copy(EC_GROUP *dest, const EC_GROUP *src)
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112 | {
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113 | BN_MONT_CTX_free(dest->field_data1);
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114 | dest->field_data1 = NULL;
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115 | BN_clear_free(dest->field_data2);
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116 | dest->field_data2 = NULL;
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117 |
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118 | if (!ossl_ec_GFp_simple_group_copy(dest, src))
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119 | return 0;
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120 |
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121 | if (src->field_data1 != NULL) {
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122 | dest->field_data1 = BN_MONT_CTX_new();
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123 | if (dest->field_data1 == NULL)
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124 | return 0;
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125 | if (!BN_MONT_CTX_copy(dest->field_data1, src->field_data1))
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126 | goto err;
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127 | }
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128 | if (src->field_data2 != NULL) {
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129 | dest->field_data2 = BN_dup(src->field_data2);
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130 | if (dest->field_data2 == NULL)
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131 | goto err;
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132 | }
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133 |
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134 | return 1;
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135 |
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136 | err:
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137 | BN_MONT_CTX_free(dest->field_data1);
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138 | dest->field_data1 = NULL;
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139 | return 0;
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140 | }
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141 |
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142 | int ossl_ec_GFp_mont_group_set_curve(EC_GROUP *group, const BIGNUM *p,
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143 | const BIGNUM *a, const BIGNUM *b,
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144 | BN_CTX *ctx)
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145 | {
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146 | BN_CTX *new_ctx = NULL;
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147 | BN_MONT_CTX *mont = NULL;
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148 | BIGNUM *one = NULL;
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149 | int ret = 0;
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150 |
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151 | BN_MONT_CTX_free(group->field_data1);
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152 | group->field_data1 = NULL;
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153 | BN_free(group->field_data2);
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154 | group->field_data2 = NULL;
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155 |
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156 | if (ctx == NULL) {
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157 | ctx = new_ctx = BN_CTX_new_ex(group->libctx);
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158 | if (ctx == NULL)
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159 | return 0;
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160 | }
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161 |
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162 | mont = BN_MONT_CTX_new();
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163 | if (mont == NULL)
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164 | goto err;
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165 | if (!BN_MONT_CTX_set(mont, p, ctx)) {
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166 | ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
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167 | goto err;
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168 | }
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169 | one = BN_new();
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170 | if (one == NULL)
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171 | goto err;
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172 | if (!BN_to_montgomery(one, BN_value_one(), mont, ctx))
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173 | goto err;
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174 |
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175 | group->field_data1 = mont;
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176 | mont = NULL;
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177 | group->field_data2 = one;
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178 | one = NULL;
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179 |
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180 | ret = ossl_ec_GFp_simple_group_set_curve(group, p, a, b, ctx);
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181 |
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182 | if (!ret) {
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183 | BN_MONT_CTX_free(group->field_data1);
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184 | group->field_data1 = NULL;
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185 | BN_free(group->field_data2);
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186 | group->field_data2 = NULL;
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187 | }
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188 |
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189 | err:
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190 | BN_free(one);
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191 | BN_CTX_free(new_ctx);
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192 | BN_MONT_CTX_free(mont);
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193 | return ret;
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194 | }
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195 |
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196 | int ossl_ec_GFp_mont_field_mul(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
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197 | const BIGNUM *b, BN_CTX *ctx)
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198 | {
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199 | if (group->field_data1 == NULL) {
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200 | ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
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201 | return 0;
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202 | }
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203 |
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204 | return BN_mod_mul_montgomery(r, a, b, group->field_data1, ctx);
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205 | }
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206 |
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207 | int ossl_ec_GFp_mont_field_sqr(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
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208 | BN_CTX *ctx)
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209 | {
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210 | if (group->field_data1 == NULL) {
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211 | ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
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212 | return 0;
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213 | }
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214 |
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215 | return BN_mod_mul_montgomery(r, a, a, group->field_data1, ctx);
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216 | }
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217 |
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218 | /*-
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219 | * Computes the multiplicative inverse of a in GF(p), storing the result in r.
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220 | * If a is zero (or equivalent), you'll get a EC_R_CANNOT_INVERT error.
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221 | * We have a Mont structure, so SCA hardening is FLT inversion.
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222 | */
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223 | int ossl_ec_GFp_mont_field_inv(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
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224 | BN_CTX *ctx)
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225 | {
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226 | BIGNUM *e = NULL;
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227 | BN_CTX *new_ctx = NULL;
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228 | int ret = 0;
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229 |
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230 | if (group->field_data1 == NULL)
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231 | return 0;
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232 |
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233 | if (ctx == NULL
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234 | && (ctx = new_ctx = BN_CTX_secure_new_ex(group->libctx)) == NULL)
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235 | return 0;
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236 |
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237 | BN_CTX_start(ctx);
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238 | if ((e = BN_CTX_get(ctx)) == NULL)
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239 | goto err;
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240 |
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241 | /* Inverse in constant time with Fermats Little Theorem */
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242 | if (!BN_set_word(e, 2))
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243 | goto err;
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244 | if (!BN_sub(e, group->field, e))
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245 | goto err;
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246 | /*-
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247 | * Exponent e is public.
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248 | * No need for scatter-gather or BN_FLG_CONSTTIME.
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249 | */
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250 | if (!BN_mod_exp_mont(r, a, e, group->field, ctx, group->field_data1))
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251 | goto err;
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252 |
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253 | /* throw an error on zero */
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254 | if (BN_is_zero(r)) {
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255 | ERR_raise(ERR_LIB_EC, EC_R_CANNOT_INVERT);
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256 | goto err;
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257 | }
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258 |
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259 | ret = 1;
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260 |
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261 | err:
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262 | BN_CTX_end(ctx);
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263 | BN_CTX_free(new_ctx);
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264 | return ret;
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265 | }
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266 |
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267 | int ossl_ec_GFp_mont_field_encode(const EC_GROUP *group, BIGNUM *r,
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268 | const BIGNUM *a, BN_CTX *ctx)
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269 | {
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270 | if (group->field_data1 == NULL) {
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271 | ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
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272 | return 0;
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273 | }
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274 |
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275 | return BN_to_montgomery(r, a, (BN_MONT_CTX *)group->field_data1, ctx);
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276 | }
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277 |
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278 | int ossl_ec_GFp_mont_field_decode(const EC_GROUP *group, BIGNUM *r,
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279 | const BIGNUM *a, BN_CTX *ctx)
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280 | {
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281 | if (group->field_data1 == NULL) {
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282 | ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
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283 | return 0;
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284 | }
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285 |
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286 | return BN_from_montgomery(r, a, group->field_data1, ctx);
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287 | }
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288 |
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289 | int ossl_ec_GFp_mont_field_set_to_one(const EC_GROUP *group, BIGNUM *r,
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290 | BN_CTX *ctx)
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291 | {
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292 | if (group->field_data2 == NULL) {
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293 | ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
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294 | return 0;
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295 | }
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296 |
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297 | if (!BN_copy(r, group->field_data2))
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298 | return 0;
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299 | return 1;
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300 | }
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