1 | /*
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2 | * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
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3 | *
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4 | * Licensed under the OpenSSL license (the "License"). You may not use
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5 | * this file except in compliance with the License. You can obtain a copy
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6 | * in the file LICENSE in the source distribution or at
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7 | * https://www.openssl.org/source/license.html
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8 | */
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9 |
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10 | /*
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11 | * NB: these functions have been "upgraded", the deprecated versions (which
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12 | * are compatibility wrappers using these functions) are in rsa_depr.c. -
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13 | * Geoff
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14 | */
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15 |
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16 | #include <stdio.h>
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17 | #include <time.h>
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18 | #include "internal/cryptlib.h"
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19 | #include <openssl/bn.h>
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20 | #include "rsa_locl.h"
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21 |
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22 | static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,
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23 | BN_GENCB *cb);
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24 |
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25 | /*
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26 | * NB: this wrapper would normally be placed in rsa_lib.c and the static
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27 | * implementation would probably be in rsa_eay.c. Nonetheless, is kept here
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28 | * so that we don't introduce a new linker dependency. Eg. any application
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29 | * that wasn't previously linking object code related to key-generation won't
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30 | * have to now just because key-generation is part of RSA_METHOD.
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31 | */
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32 | int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
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33 | {
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34 | if (rsa->meth->rsa_keygen)
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35 | return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
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36 | return rsa_builtin_keygen(rsa, bits, e_value, cb);
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37 | }
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38 |
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39 | static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,
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40 | BN_GENCB *cb)
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41 | {
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42 | BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *r3 = NULL, *tmp;
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43 | int bitsp, bitsq, ok = -1, n = 0;
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44 | BN_CTX *ctx = NULL;
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45 |
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46 | ctx = BN_CTX_new();
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47 | if (ctx == NULL)
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48 | goto err;
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49 | BN_CTX_start(ctx);
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50 | r0 = BN_CTX_get(ctx);
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51 | r1 = BN_CTX_get(ctx);
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52 | r2 = BN_CTX_get(ctx);
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53 | r3 = BN_CTX_get(ctx);
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54 | if (r3 == NULL)
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55 | goto err;
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56 |
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57 | bitsp = (bits + 1) / 2;
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58 | bitsq = bits - bitsp;
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59 |
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60 | /* We need the RSA components non-NULL */
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61 | if (!rsa->n && ((rsa->n = BN_new()) == NULL))
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62 | goto err;
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63 | if (!rsa->d && ((rsa->d = BN_secure_new()) == NULL))
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64 | goto err;
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65 | if (!rsa->e && ((rsa->e = BN_new()) == NULL))
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66 | goto err;
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67 | if (!rsa->p && ((rsa->p = BN_secure_new()) == NULL))
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68 | goto err;
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69 | if (!rsa->q && ((rsa->q = BN_secure_new()) == NULL))
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70 | goto err;
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71 | if (!rsa->dmp1 && ((rsa->dmp1 = BN_secure_new()) == NULL))
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72 | goto err;
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73 | if (!rsa->dmq1 && ((rsa->dmq1 = BN_secure_new()) == NULL))
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74 | goto err;
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75 | if (!rsa->iqmp && ((rsa->iqmp = BN_secure_new()) == NULL))
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76 | goto err;
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77 |
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78 | if (BN_copy(rsa->e, e_value) == NULL)
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79 | goto err;
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80 |
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81 | /* generate p and q */
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82 | for (;;) {
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83 | if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb))
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84 | goto err;
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85 | if (!BN_sub(r2, rsa->p, BN_value_one()))
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86 | goto err;
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87 | if (!BN_gcd(r1, r2, rsa->e, ctx))
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88 | goto err;
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89 | if (BN_is_one(r1))
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90 | break;
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91 | if (!BN_GENCB_call(cb, 2, n++))
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92 | goto err;
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93 | }
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94 | if (!BN_GENCB_call(cb, 3, 0))
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95 | goto err;
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96 | for (;;) {
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97 | /*
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98 | * When generating ridiculously small keys, we can get stuck
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99 | * continually regenerating the same prime values. Check for this and
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100 | * bail if it happens 3 times.
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101 | */
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102 | unsigned int degenerate = 0;
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103 | do {
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104 | if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, cb))
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105 | goto err;
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106 | } while ((BN_cmp(rsa->p, rsa->q) == 0) && (++degenerate < 3));
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107 | if (degenerate == 3) {
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108 | ok = 0; /* we set our own err */
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109 | RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL);
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110 | goto err;
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111 | }
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112 | if (!BN_sub(r2, rsa->q, BN_value_one()))
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113 | goto err;
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114 | if (!BN_gcd(r1, r2, rsa->e, ctx))
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115 | goto err;
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116 | if (BN_is_one(r1))
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117 | break;
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118 | if (!BN_GENCB_call(cb, 2, n++))
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119 | goto err;
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120 | }
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121 | if (!BN_GENCB_call(cb, 3, 1))
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122 | goto err;
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123 | if (BN_cmp(rsa->p, rsa->q) < 0) {
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124 | tmp = rsa->p;
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125 | rsa->p = rsa->q;
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126 | rsa->q = tmp;
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127 | }
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128 |
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129 | /* calculate n */
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130 | if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx))
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131 | goto err;
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132 |
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133 | /* calculate d */
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134 | if (!BN_sub(r1, rsa->p, BN_value_one()))
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135 | goto err; /* p-1 */
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136 | if (!BN_sub(r2, rsa->q, BN_value_one()))
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137 | goto err; /* q-1 */
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138 | if (!BN_mul(r0, r1, r2, ctx))
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139 | goto err; /* (p-1)(q-1) */
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140 | {
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141 | BIGNUM *pr0 = BN_new();
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142 |
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143 | if (pr0 == NULL)
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144 | goto err;
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145 | BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);
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146 | if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx)) {
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147 | BN_free(pr0);
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148 | goto err; /* d */
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149 | }
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150 | /* We MUST free pr0 before any further use of r0 */
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151 | BN_free(pr0);
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152 | }
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153 |
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154 | {
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155 | BIGNUM *d = BN_new();
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156 |
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157 | if (d == NULL)
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158 | goto err;
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159 | BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
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160 |
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161 | if ( /* calculate d mod (p-1) */
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162 | !BN_mod(rsa->dmp1, d, r1, ctx)
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163 | /* calculate d mod (q-1) */
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164 | || !BN_mod(rsa->dmq1, d, r2, ctx)) {
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165 | BN_free(d);
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166 | goto err;
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167 | }
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168 | /* We MUST free d before any further use of rsa->d */
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169 | BN_free(d);
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170 | }
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171 |
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172 | {
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173 | BIGNUM *p = BN_new();
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174 |
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175 | if (p == NULL)
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176 | goto err;
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177 | BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
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178 |
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179 | /* calculate inverse of q mod p */
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180 | if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx)) {
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181 | BN_free(p);
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182 | goto err;
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183 | }
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184 | /* We MUST free p before any further use of rsa->p */
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185 | BN_free(p);
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186 | }
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187 |
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188 | ok = 1;
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189 | err:
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190 | if (ok == -1) {
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191 | RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN);
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192 | ok = 0;
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193 | }
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194 | if (ctx != NULL)
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195 | BN_CTX_end(ctx);
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196 | BN_CTX_free(ctx);
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197 |
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198 | return ok;
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199 | }
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