Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 1 | /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
| 2 | * All rights reserved. |
| 3 | * |
| 4 | * This package is an SSL implementation written |
| 5 | * by Eric Young (eay@cryptsoft.com). |
| 6 | * The implementation was written so as to conform with Netscapes SSL. |
| 7 | * |
| 8 | * This library is free for commercial and non-commercial use as long as |
| 9 | * the following conditions are aheared to. The following conditions |
| 10 | * apply to all code found in this distribution, be it the RC4, RSA, |
| 11 | * lhash, DES, etc., code; not just the SSL code. The SSL documentation |
| 12 | * included with this distribution is covered by the same copyright terms |
| 13 | * except that the holder is Tim Hudson (tjh@cryptsoft.com). |
| 14 | * |
| 15 | * Copyright remains Eric Young's, and as such any Copyright notices in |
| 16 | * the code are not to be removed. |
| 17 | * If this package is used in a product, Eric Young should be given attribution |
| 18 | * as the author of the parts of the library used. |
| 19 | * This can be in the form of a textual message at program startup or |
| 20 | * in documentation (online or textual) provided with the package. |
| 21 | * |
| 22 | * Redistribution and use in source and binary forms, with or without |
| 23 | * modification, are permitted provided that the following conditions |
| 24 | * are met: |
| 25 | * 1. Redistributions of source code must retain the copyright |
| 26 | * notice, this list of conditions and the following disclaimer. |
| 27 | * 2. Redistributions in binary form must reproduce the above copyright |
| 28 | * notice, this list of conditions and the following disclaimer in the |
| 29 | * documentation and/or other materials provided with the distribution. |
| 30 | * 3. All advertising materials mentioning features or use of this software |
| 31 | * must display the following acknowledgement: |
| 32 | * "This product includes cryptographic software written by |
| 33 | * Eric Young (eay@cryptsoft.com)" |
| 34 | * The word 'cryptographic' can be left out if the rouines from the library |
| 35 | * being used are not cryptographic related :-). |
| 36 | * 4. If you include any Windows specific code (or a derivative thereof) from |
| 37 | * the apps directory (application code) you must include an acknowledgement: |
| 38 | * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" |
| 39 | * |
| 40 | * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND |
| 41 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 42 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 43 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| 44 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 45 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 46 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 47 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 48 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 49 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 50 | * SUCH DAMAGE. |
| 51 | * |
| 52 | * The licence and distribution terms for any publically available version or |
| 53 | * derivative of this code cannot be changed. i.e. this code cannot simply be |
| 54 | * copied and put under another distribution licence |
| 55 | * [including the GNU Public Licence.] |
| 56 | */ |
| 57 | /* ==================================================================== |
| 58 | * Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved. |
| 59 | * |
| 60 | * Redistribution and use in source and binary forms, with or without |
| 61 | * modification, are permitted provided that the following conditions |
| 62 | * are met: |
| 63 | * |
| 64 | * 1. Redistributions of source code must retain the above copyright |
| 65 | * notice, this list of conditions and the following disclaimer. |
| 66 | * |
| 67 | * 2. Redistributions in binary form must reproduce the above copyright |
| 68 | * notice, this list of conditions and the following disclaimer in |
| 69 | * the documentation and/or other materials provided with the |
| 70 | * distribution. |
| 71 | * |
| 72 | * 3. All advertising materials mentioning features or use of this |
| 73 | * software must display the following acknowledgment: |
| 74 | * "This product includes software developed by the OpenSSL Project |
| 75 | * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" |
| 76 | * |
| 77 | * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to |
| 78 | * endorse or promote products derived from this software without |
| 79 | * prior written permission. For written permission, please contact |
| 80 | * openssl-core@openssl.org. |
| 81 | * |
| 82 | * 5. Products derived from this software may not be called "OpenSSL" |
| 83 | * nor may "OpenSSL" appear in their names without prior written |
| 84 | * permission of the OpenSSL Project. |
| 85 | * |
| 86 | * 6. Redistributions of any form whatsoever must retain the following |
| 87 | * acknowledgment: |
| 88 | * "This product includes software developed by the OpenSSL Project |
| 89 | * for use in the OpenSSL Toolkit (http://www.openssl.org/)" |
| 90 | * |
| 91 | * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY |
| 92 | * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 93 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 94 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR |
| 95 | * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 96 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 97 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| 98 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 99 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| 100 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 101 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
| 102 | * OF THE POSSIBILITY OF SUCH DAMAGE. |
| 103 | * ==================================================================== |
| 104 | * |
| 105 | * This product includes cryptographic software written by Eric Young |
| 106 | * (eay@cryptsoft.com). This product includes software written by Tim |
| 107 | * Hudson (tjh@cryptsoft.com). */ |
| 108 | |
| 109 | #include <openssl/bn.h> |
| 110 | |
| 111 | #include <openssl/err.h> |
| 112 | |
| 113 | #include "internal.h" |
| 114 | |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 115 | |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 116 | int BN_mod_inverse_odd(BIGNUM *out, int *out_no_inverse, const BIGNUM *a, |
| 117 | const BIGNUM *n, BN_CTX *ctx) { |
| 118 | *out_no_inverse = 0; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 119 | |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 120 | if (!BN_is_odd(n)) { |
| 121 | OPENSSL_PUT_ERROR(BN, BN_R_CALLED_WITH_EVEN_MODULUS); |
| 122 | return 0; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 123 | } |
| 124 | |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 125 | if (BN_is_negative(a) || BN_cmp(a, n) >= 0) { |
| 126 | OPENSSL_PUT_ERROR(BN, BN_R_INPUT_NOT_REDUCED); |
| 127 | return 0; |
| 128 | } |
| 129 | |
| 130 | BIGNUM *A, *B, *X, *Y; |
| 131 | int ret = 0; |
| 132 | int sign; |
Kenny Root | b849459 | 2015-09-25 02:29:14 +0000 | [diff] [blame] | 133 | |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 134 | BN_CTX_start(ctx); |
| 135 | A = BN_CTX_get(ctx); |
| 136 | B = BN_CTX_get(ctx); |
| 137 | X = BN_CTX_get(ctx); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 138 | Y = BN_CTX_get(ctx); |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 139 | if (Y == NULL) { |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 140 | goto err; |
| 141 | } |
| 142 | |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 143 | BIGNUM *R = out; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 144 | |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 145 | BN_zero(Y); |
Adam Langley | e9ada86 | 2015-05-11 17:20:37 -0700 | [diff] [blame] | 146 | if (!BN_one(X) || BN_copy(B, a) == NULL || BN_copy(A, n) == NULL) { |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 147 | goto err; |
| 148 | } |
| 149 | A->neg = 0; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 150 | sign = -1; |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 151 | // From B = a mod |n|, A = |n| it follows that |
| 152 | // |
| 153 | // 0 <= B < A, |
| 154 | // -sign*X*a == B (mod |n|), |
| 155 | // sign*Y*a == A (mod |n|). |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 156 | |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 157 | // Binary inversion algorithm; requires odd modulus. This is faster than the |
| 158 | // general algorithm if the modulus is sufficiently small (about 400 .. 500 |
| 159 | // bits on 32-bit systems, but much more on 64-bit systems) |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 160 | int shift; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 161 | |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 162 | while (!BN_is_zero(B)) { |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 163 | // 0 < B < |n|, |
| 164 | // 0 < A <= |n|, |
| 165 | // (1) -sign*X*a == B (mod |n|), |
| 166 | // (2) sign*Y*a == A (mod |n|) |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 167 | |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 168 | // Now divide B by the maximum possible power of two in the integers, |
| 169 | // and divide X by the same value mod |n|. |
| 170 | // When we're done, (1) still holds. |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 171 | shift = 0; |
| 172 | while (!BN_is_bit_set(B, shift)) { |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 173 | // note that 0 < B |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 174 | shift++; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 175 | |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 176 | if (BN_is_odd(X)) { |
| 177 | if (!BN_uadd(X, X, n)) { |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 178 | goto err; |
| 179 | } |
| 180 | } |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 181 | // now X is even, so we can easily divide it by two |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 182 | if (!BN_rshift1(X, X)) { |
| 183 | goto err; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 184 | } |
| 185 | } |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 186 | if (shift > 0) { |
| 187 | if (!BN_rshift(B, B, shift)) { |
| 188 | goto err; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 189 | } |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 190 | } |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 191 | |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 192 | // Same for A and Y. Afterwards, (2) still holds. |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 193 | shift = 0; |
| 194 | while (!BN_is_bit_set(A, shift)) { |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 195 | // note that 0 < A |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 196 | shift++; |
| 197 | |
| 198 | if (BN_is_odd(Y)) { |
| 199 | if (!BN_uadd(Y, Y, n)) { |
| 200 | goto err; |
| 201 | } |
| 202 | } |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 203 | // now Y is even |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 204 | if (!BN_rshift1(Y, Y)) { |
| 205 | goto err; |
| 206 | } |
| 207 | } |
| 208 | if (shift > 0) { |
| 209 | if (!BN_rshift(A, A, shift)) { |
| 210 | goto err; |
| 211 | } |
| 212 | } |
| 213 | |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 214 | // We still have (1) and (2). |
| 215 | // Both A and B are odd. |
| 216 | // The following computations ensure that |
| 217 | // |
| 218 | // 0 <= B < |n|, |
| 219 | // 0 < A < |n|, |
| 220 | // (1) -sign*X*a == B (mod |n|), |
| 221 | // (2) sign*Y*a == A (mod |n|), |
| 222 | // |
| 223 | // and that either A or B is even in the next iteration. |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 224 | if (BN_ucmp(B, A) >= 0) { |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 225 | // -sign*(X + Y)*a == B - A (mod |n|) |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 226 | if (!BN_uadd(X, X, Y)) { |
| 227 | goto err; |
| 228 | } |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 229 | // NB: we could use BN_mod_add_quick(X, X, Y, n), but that |
| 230 | // actually makes the algorithm slower |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 231 | if (!BN_usub(B, B, A)) { |
| 232 | goto err; |
| 233 | } |
| 234 | } else { |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 235 | // sign*(X + Y)*a == A - B (mod |n|) |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 236 | if (!BN_uadd(Y, Y, X)) { |
| 237 | goto err; |
| 238 | } |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 239 | // as above, BN_mod_add_quick(Y, Y, X, n) would slow things down |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 240 | if (!BN_usub(A, A, B)) { |
| 241 | goto err; |
| 242 | } |
| 243 | } |
| 244 | } |
| 245 | |
| 246 | if (!BN_is_one(A)) { |
| 247 | *out_no_inverse = 1; |
| 248 | OPENSSL_PUT_ERROR(BN, BN_R_NO_INVERSE); |
| 249 | goto err; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 250 | } |
| 251 | |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 252 | // The while loop (Euclid's algorithm) ends when |
| 253 | // A == gcd(a,n); |
| 254 | // we have |
| 255 | // sign*Y*a == A (mod |n|), |
| 256 | // where Y is non-negative. |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 257 | |
| 258 | if (sign < 0) { |
| 259 | if (!BN_sub(Y, n, Y)) { |
| 260 | goto err; |
| 261 | } |
| 262 | } |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 263 | // Now Y*a == A (mod |n|). |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 264 | |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 265 | // Y*a == 1 (mod |n|) |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 266 | if (!Y->neg && BN_ucmp(Y, n) < 0) { |
| 267 | if (!BN_copy(R, Y)) { |
| 268 | goto err; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 269 | } |
| 270 | } else { |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 271 | if (!BN_nnmod(R, Y, n, ctx)) { |
| 272 | goto err; |
| 273 | } |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 274 | } |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 275 | |
| 276 | ret = 1; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 277 | |
| 278 | err: |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 279 | BN_CTX_end(ctx); |
| 280 | return ret; |
| 281 | } |
| 282 | |
Kenny Root | b849459 | 2015-09-25 02:29:14 +0000 | [diff] [blame] | 283 | BIGNUM *BN_mod_inverse(BIGNUM *out, const BIGNUM *a, const BIGNUM *n, |
| 284 | BN_CTX *ctx) { |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 285 | BIGNUM *new_out = NULL; |
| 286 | if (out == NULL) { |
| 287 | new_out = BN_new(); |
| 288 | if (new_out == NULL) { |
| 289 | OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE); |
| 290 | return NULL; |
| 291 | } |
| 292 | out = new_out; |
| 293 | } |
| 294 | |
| 295 | int ok = 0; |
Steven Valdez | b0b45c6 | 2017-01-17 16:23:54 -0500 | [diff] [blame] | 296 | BIGNUM *a_reduced = NULL; |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 297 | if (a->neg || BN_ucmp(a, n) >= 0) { |
| 298 | a_reduced = BN_dup(a); |
| 299 | if (a_reduced == NULL) { |
| 300 | goto err; |
| 301 | } |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 302 | if (!BN_nnmod(a_reduced, a_reduced, n, ctx)) { |
| 303 | goto err; |
| 304 | } |
| 305 | a = a_reduced; |
| 306 | } |
| 307 | |
Steven Valdez | b0b45c6 | 2017-01-17 16:23:54 -0500 | [diff] [blame] | 308 | int no_inverse; |
| 309 | if (!BN_is_odd(n)) { |
Robert Sloan | 49d063b | 2018-04-03 11:30:38 -0700 | [diff] [blame] | 310 | if (!bn_mod_inverse_consttime(out, &no_inverse, a, n, ctx)) { |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 311 | goto err; |
| 312 | } |
| 313 | } else if (!BN_mod_inverse_odd(out, &no_inverse, a, n, ctx)) { |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 314 | goto err; |
| 315 | } |
| 316 | |
| 317 | ok = 1; |
| 318 | |
| 319 | err: |
| 320 | if (!ok) { |
| 321 | BN_free(new_out); |
| 322 | out = NULL; |
| 323 | } |
| 324 | BN_free(a_reduced); |
| 325 | return out; |
Kenny Root | b849459 | 2015-09-25 02:29:14 +0000 | [diff] [blame] | 326 | } |
| 327 | |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 328 | int BN_mod_inverse_blinded(BIGNUM *out, int *out_no_inverse, const BIGNUM *a, |
| 329 | const BN_MONT_CTX *mont, BN_CTX *ctx) { |
| 330 | *out_no_inverse = 0; |
| 331 | |
| 332 | if (BN_is_negative(a) || BN_cmp(a, &mont->N) >= 0) { |
| 333 | OPENSSL_PUT_ERROR(BN, BN_R_INPUT_NOT_REDUCED); |
| 334 | return 0; |
| 335 | } |
| 336 | |
| 337 | int ret = 0; |
| 338 | BIGNUM blinding_factor; |
| 339 | BN_init(&blinding_factor); |
| 340 | |
| 341 | if (!BN_rand_range_ex(&blinding_factor, 1, &mont->N) || |
| 342 | !BN_mod_mul_montgomery(out, &blinding_factor, a, mont, ctx) || |
| 343 | !BN_mod_inverse_odd(out, out_no_inverse, out, &mont->N, ctx) || |
| 344 | !BN_mod_mul_montgomery(out, &blinding_factor, out, mont, ctx)) { |
| 345 | OPENSSL_PUT_ERROR(BN, ERR_R_BN_LIB); |
| 346 | goto err; |
| 347 | } |
| 348 | |
| 349 | ret = 1; |
| 350 | |
| 351 | err: |
| 352 | BN_free(&blinding_factor); |
| 353 | return ret; |
| 354 | } |
| 355 | |
Robert Sloan | 69939df | 2017-01-09 10:53:07 -0800 | [diff] [blame] | 356 | int bn_mod_inverse_prime(BIGNUM *out, const BIGNUM *a, const BIGNUM *p, |
| 357 | BN_CTX *ctx, const BN_MONT_CTX *mont_p) { |
| 358 | BN_CTX_start(ctx); |
| 359 | BIGNUM *p_minus_2 = BN_CTX_get(ctx); |
| 360 | int ok = p_minus_2 != NULL && |
| 361 | BN_copy(p_minus_2, p) && |
| 362 | BN_sub_word(p_minus_2, 2) && |
| 363 | BN_mod_exp_mont(out, a, p_minus_2, p, ctx, mont_p); |
| 364 | BN_CTX_end(ctx); |
| 365 | return ok; |
| 366 | } |
| 367 | |
| 368 | int bn_mod_inverse_secret_prime(BIGNUM *out, const BIGNUM *a, const BIGNUM *p, |
| 369 | BN_CTX *ctx, const BN_MONT_CTX *mont_p) { |
| 370 | BN_CTX_start(ctx); |
| 371 | BIGNUM *p_minus_2 = BN_CTX_get(ctx); |
| 372 | int ok = p_minus_2 != NULL && |
| 373 | BN_copy(p_minus_2, p) && |
| 374 | BN_sub_word(p_minus_2, 2) && |
| 375 | BN_mod_exp_mont_consttime(out, a, p_minus_2, p, ctx, mont_p); |
| 376 | BN_CTX_end(ctx); |
| 377 | return ok; |
| 378 | } |