bn_exp2.c 11 KB

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  1. /* crypto/bn/bn_exp2.c */
  2. /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  3. * All rights reserved.
  4. *
  5. * This package is an SSL implementation written
  6. * by Eric Young (eay@cryptsoft.com).
  7. * The implementation was written so as to conform with Netscapes SSL.
  8. *
  9. * This library is free for commercial and non-commercial use as long as
  10. * the following conditions are aheared to. The following conditions
  11. * apply to all code found in this distribution, be it the RC4, RSA,
  12. * lhash, DES, etc., code; not just the SSL code. The SSL documentation
  13. * included with this distribution is covered by the same copyright terms
  14. * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15. *
  16. * Copyright remains Eric Young's, and as such any Copyright notices in
  17. * the code are not to be removed.
  18. * If this package is used in a product, Eric Young should be given attribution
  19. * as the author of the parts of the library used.
  20. * This can be in the form of a textual message at program startup or
  21. * in documentation (online or textual) provided with the package.
  22. *
  23. * Redistribution and use in source and binary forms, with or without
  24. * modification, are permitted provided that the following conditions
  25. * are met:
  26. * 1. Redistributions of source code must retain the copyright
  27. * notice, this list of conditions and the following disclaimer.
  28. * 2. Redistributions in binary form must reproduce the above copyright
  29. * notice, this list of conditions and the following disclaimer in the
  30. * documentation and/or other materials provided with the distribution.
  31. * 3. All advertising materials mentioning features or use of this software
  32. * must display the following acknowledgement:
  33. * "This product includes cryptographic software written by
  34. * Eric Young (eay@cryptsoft.com)"
  35. * The word 'cryptographic' can be left out if the rouines from the library
  36. * being used are not cryptographic related :-).
  37. * 4. If you include any Windows specific code (or a derivative thereof) from
  38. * the apps directory (application code) you must include an acknowledgement:
  39. * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40. *
  41. * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42. * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44. * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45. * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46. * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47. * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48. * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50. * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51. * SUCH DAMAGE.
  52. *
  53. * The licence and distribution terms for any publically available version or
  54. * derivative of this code cannot be changed. i.e. this code cannot simply be
  55. * copied and put under another distribution licence
  56. * [including the GNU Public Licence.]
  57. */
  58. /* ====================================================================
  59. * Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved.
  60. *
  61. * Redistribution and use in source and binary forms, with or without
  62. * modification, are permitted provided that the following conditions
  63. * are met:
  64. *
  65. * 1. Redistributions of source code must retain the above copyright
  66. * notice, this list of conditions and the following disclaimer.
  67. *
  68. * 2. Redistributions in binary form must reproduce the above copyright
  69. * notice, this list of conditions and the following disclaimer in
  70. * the documentation and/or other materials provided with the
  71. * distribution.
  72. *
  73. * 3. All advertising materials mentioning features or use of this
  74. * software must display the following acknowledgment:
  75. * "This product includes software developed by the OpenSSL Project
  76. * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  77. *
  78. * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  79. * endorse or promote products derived from this software without
  80. * prior written permission. For written permission, please contact
  81. * openssl-core@openssl.org.
  82. *
  83. * 5. Products derived from this software may not be called "OpenSSL"
  84. * nor may "OpenSSL" appear in their names without prior written
  85. * permission of the OpenSSL Project.
  86. *
  87. * 6. Redistributions of any form whatsoever must retain the following
  88. * acknowledgment:
  89. * "This product includes software developed by the OpenSSL Project
  90. * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  91. *
  92. * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  93. * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  94. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  95. * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
  96. * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  97. * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  98. * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  99. * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  100. * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  101. * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  102. * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  103. * OF THE POSSIBILITY OF SUCH DAMAGE.
  104. * ====================================================================
  105. *
  106. * This product includes cryptographic software written by Eric Young
  107. * (eay@cryptsoft.com). This product includes software written by Tim
  108. * Hudson (tjh@cryptsoft.com).
  109. *
  110. */
  111. #include <stdio.h>
  112. #include "internal/cryptlib.h"
  113. #include "bn_lcl.h"
  114. #define TABLE_SIZE 32
  115. int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
  116. const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m,
  117. BN_CTX *ctx, BN_MONT_CTX *in_mont)
  118. {
  119. int i, j, bits, b, bits1, bits2, ret =
  120. 0, wpos1, wpos2, window1, window2, wvalue1, wvalue2;
  121. int r_is_one = 1;
  122. BIGNUM *d, *r;
  123. const BIGNUM *a_mod_m;
  124. /* Tables of variables obtained from 'ctx' */
  125. BIGNUM *val1[TABLE_SIZE], *val2[TABLE_SIZE];
  126. BN_MONT_CTX *mont = NULL;
  127. bn_check_top(a1);
  128. bn_check_top(p1);
  129. bn_check_top(a2);
  130. bn_check_top(p2);
  131. bn_check_top(m);
  132. if (!(m->d[0] & 1)) {
  133. BNerr(BN_F_BN_MOD_EXP2_MONT, BN_R_CALLED_WITH_EVEN_MODULUS);
  134. return (0);
  135. }
  136. bits1 = BN_num_bits(p1);
  137. bits2 = BN_num_bits(p2);
  138. if ((bits1 == 0) && (bits2 == 0)) {
  139. ret = BN_one(rr);
  140. return ret;
  141. }
  142. bits = (bits1 > bits2) ? bits1 : bits2;
  143. BN_CTX_start(ctx);
  144. d = BN_CTX_get(ctx);
  145. r = BN_CTX_get(ctx);
  146. val1[0] = BN_CTX_get(ctx);
  147. val2[0] = BN_CTX_get(ctx);
  148. if (!d || !r || !val1[0] || !val2[0])
  149. goto err;
  150. if (in_mont != NULL)
  151. mont = in_mont;
  152. else {
  153. if ((mont = BN_MONT_CTX_new()) == NULL)
  154. goto err;
  155. if (!BN_MONT_CTX_set(mont, m, ctx))
  156. goto err;
  157. }
  158. window1 = BN_window_bits_for_exponent_size(bits1);
  159. window2 = BN_window_bits_for_exponent_size(bits2);
  160. /*
  161. * Build table for a1: val1[i] := a1^(2*i + 1) mod m for i = 0 .. 2^(window1-1)
  162. */
  163. if (a1->neg || BN_ucmp(a1, m) >= 0) {
  164. if (!BN_mod(val1[0], a1, m, ctx))
  165. goto err;
  166. a_mod_m = val1[0];
  167. } else
  168. a_mod_m = a1;
  169. if (BN_is_zero(a_mod_m)) {
  170. BN_zero(rr);
  171. ret = 1;
  172. goto err;
  173. }
  174. if (!BN_to_montgomery(val1[0], a_mod_m, mont, ctx))
  175. goto err;
  176. if (window1 > 1) {
  177. if (!BN_mod_mul_montgomery(d, val1[0], val1[0], mont, ctx))
  178. goto err;
  179. j = 1 << (window1 - 1);
  180. for (i = 1; i < j; i++) {
  181. if (((val1[i] = BN_CTX_get(ctx)) == NULL) ||
  182. !BN_mod_mul_montgomery(val1[i], val1[i - 1], d, mont, ctx))
  183. goto err;
  184. }
  185. }
  186. /*
  187. * Build table for a2: val2[i] := a2^(2*i + 1) mod m for i = 0 .. 2^(window2-1)
  188. */
  189. if (a2->neg || BN_ucmp(a2, m) >= 0) {
  190. if (!BN_mod(val2[0], a2, m, ctx))
  191. goto err;
  192. a_mod_m = val2[0];
  193. } else
  194. a_mod_m = a2;
  195. if (BN_is_zero(a_mod_m)) {
  196. BN_zero(rr);
  197. ret = 1;
  198. goto err;
  199. }
  200. if (!BN_to_montgomery(val2[0], a_mod_m, mont, ctx))
  201. goto err;
  202. if (window2 > 1) {
  203. if (!BN_mod_mul_montgomery(d, val2[0], val2[0], mont, ctx))
  204. goto err;
  205. j = 1 << (window2 - 1);
  206. for (i = 1; i < j; i++) {
  207. if (((val2[i] = BN_CTX_get(ctx)) == NULL) ||
  208. !BN_mod_mul_montgomery(val2[i], val2[i - 1], d, mont, ctx))
  209. goto err;
  210. }
  211. }
  212. /* Now compute the power product, using independent windows. */
  213. r_is_one = 1;
  214. wvalue1 = 0; /* The 'value' of the first window */
  215. wvalue2 = 0; /* The 'value' of the second window */
  216. wpos1 = 0; /* If wvalue1 > 0, the bottom bit of the
  217. * first window */
  218. wpos2 = 0; /* If wvalue2 > 0, the bottom bit of the
  219. * second window */
  220. if (!BN_to_montgomery(r, BN_value_one(), mont, ctx))
  221. goto err;
  222. for (b = bits - 1; b >= 0; b--) {
  223. if (!r_is_one) {
  224. if (!BN_mod_mul_montgomery(r, r, r, mont, ctx))
  225. goto err;
  226. }
  227. if (!wvalue1)
  228. if (BN_is_bit_set(p1, b)) {
  229. /*
  230. * consider bits b-window1+1 .. b for this window
  231. */
  232. i = b - window1 + 1;
  233. while (!BN_is_bit_set(p1, i)) /* works for i<0 */
  234. i++;
  235. wpos1 = i;
  236. wvalue1 = 1;
  237. for (i = b - 1; i >= wpos1; i--) {
  238. wvalue1 <<= 1;
  239. if (BN_is_bit_set(p1, i))
  240. wvalue1++;
  241. }
  242. }
  243. if (!wvalue2)
  244. if (BN_is_bit_set(p2, b)) {
  245. /*
  246. * consider bits b-window2+1 .. b for this window
  247. */
  248. i = b - window2 + 1;
  249. while (!BN_is_bit_set(p2, i))
  250. i++;
  251. wpos2 = i;
  252. wvalue2 = 1;
  253. for (i = b - 1; i >= wpos2; i--) {
  254. wvalue2 <<= 1;
  255. if (BN_is_bit_set(p2, i))
  256. wvalue2++;
  257. }
  258. }
  259. if (wvalue1 && b == wpos1) {
  260. /* wvalue1 is odd and < 2^window1 */
  261. if (!BN_mod_mul_montgomery(r, r, val1[wvalue1 >> 1], mont, ctx))
  262. goto err;
  263. wvalue1 = 0;
  264. r_is_one = 0;
  265. }
  266. if (wvalue2 && b == wpos2) {
  267. /* wvalue2 is odd and < 2^window2 */
  268. if (!BN_mod_mul_montgomery(r, r, val2[wvalue2 >> 1], mont, ctx))
  269. goto err;
  270. wvalue2 = 0;
  271. r_is_one = 0;
  272. }
  273. }
  274. if (!BN_from_montgomery(rr, r, mont, ctx))
  275. goto err;
  276. ret = 1;
  277. err:
  278. if (in_mont == NULL)
  279. BN_MONT_CTX_free(mont);
  280. BN_CTX_end(ctx);
  281. bn_check_top(rr);
  282. return (ret);
  283. }