dsa_gen.c revision 306195
1/* crypto/dsa/dsa_gen.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#undef GENUINE_DSA 60 61#ifdef GENUINE_DSA 62/* 63 * Parameter generation follows the original release of FIPS PUB 186, 64 * Appendix 2.2 (i.e. use SHA as defined in FIPS PUB 180) 65 */ 66# define HASH EVP_sha() 67#else 68/* 69 * Parameter generation follows the updated Appendix 2.2 for FIPS PUB 186, 70 * also Appendix 2.2 of FIPS PUB 186-1 (i.e. use SHA as defined in FIPS PUB 71 * 180-1) 72 */ 73# define HASH EVP_sha1() 74#endif 75 76#include <openssl/opensslconf.h> /* To see if OPENSSL_NO_SHA is defined */ 77 78#ifndef OPENSSL_NO_SHA 79 80# include <stdio.h> 81# include "cryptlib.h" 82# include <openssl/evp.h> 83# include <openssl/bn.h> 84# include <openssl/rand.h> 85# include <openssl/sha.h> 86# include "dsa_locl.h" 87 88# ifdef OPENSSL_FIPS 89/* Workaround bug in prototype */ 90# define fips_dsa_builtin_paramgen2 fips_dsa_paramgen_bad 91# include <openssl/fips.h> 92# endif 93 94int DSA_generate_parameters_ex(DSA *ret, int bits, 95 const unsigned char *seed_in, int seed_len, 96 int *counter_ret, unsigned long *h_ret, 97 BN_GENCB *cb) 98{ 99# ifdef OPENSSL_FIPS 100 if (FIPS_mode() && !(ret->meth->flags & DSA_FLAG_FIPS_METHOD) 101 && !(ret->flags & DSA_FLAG_NON_FIPS_ALLOW)) { 102 DSAerr(DSA_F_DSA_GENERATE_PARAMETERS_EX, DSA_R_NON_FIPS_DSA_METHOD); 103 return 0; 104 } 105# endif 106 if (ret->meth->dsa_paramgen) 107 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len, 108 counter_ret, h_ret, cb); 109# ifdef OPENSSL_FIPS 110 else if (FIPS_mode()) { 111 return FIPS_dsa_generate_parameters_ex(ret, bits, 112 seed_in, seed_len, 113 counter_ret, h_ret, cb); 114 } 115# endif 116 else { 117 const EVP_MD *evpmd = bits >= 2048 ? EVP_sha256() : EVP_sha1(); 118 size_t qbits = EVP_MD_size(evpmd) * 8; 119 120 return dsa_builtin_paramgen(ret, bits, qbits, evpmd, 121 seed_in, seed_len, NULL, counter_ret, 122 h_ret, cb); 123 } 124} 125 126int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits, 127 const EVP_MD *evpmd, const unsigned char *seed_in, 128 size_t seed_len, unsigned char *seed_out, 129 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb) 130{ 131 int ok = 0; 132 unsigned char seed[SHA256_DIGEST_LENGTH]; 133 unsigned char md[SHA256_DIGEST_LENGTH]; 134 unsigned char buf[SHA256_DIGEST_LENGTH], buf2[SHA256_DIGEST_LENGTH]; 135 BIGNUM *r0, *W, *X, *c, *test; 136 BIGNUM *g = NULL, *q = NULL, *p = NULL; 137 BN_MONT_CTX *mont = NULL; 138 int i, k, n = 0, m = 0, qsize = qbits >> 3; 139 int counter = 0; 140 int r = 0; 141 BN_CTX *ctx = NULL; 142 unsigned int h = 2; 143 144 if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH && 145 qsize != SHA256_DIGEST_LENGTH) 146 /* invalid q size */ 147 return 0; 148 149 if (evpmd == NULL) 150 /* use SHA1 as default */ 151 evpmd = EVP_sha1(); 152 153 if (bits < 512) 154 bits = 512; 155 156 bits = (bits + 63) / 64 * 64; 157 158 /* 159 * NB: seed_len == 0 is special case: copy generated seed to seed_in if 160 * it is not NULL. 161 */ 162 if (seed_len && (seed_len < (size_t)qsize)) 163 seed_in = NULL; /* seed buffer too small -- ignore */ 164 if (seed_len > (size_t)qsize) 165 seed_len = qsize; /* App. 2.2 of FIPS PUB 186 allows larger 166 * SEED, but our internal buffers are 167 * restricted to 160 bits */ 168 if (seed_in != NULL) 169 memcpy(seed, seed_in, seed_len); 170 171 if ((mont = BN_MONT_CTX_new()) == NULL) 172 goto err; 173 174 if ((ctx = BN_CTX_new()) == NULL) 175 goto err; 176 177 BN_CTX_start(ctx); 178 179 r0 = BN_CTX_get(ctx); 180 g = BN_CTX_get(ctx); 181 W = BN_CTX_get(ctx); 182 q = BN_CTX_get(ctx); 183 X = BN_CTX_get(ctx); 184 c = BN_CTX_get(ctx); 185 p = BN_CTX_get(ctx); 186 test = BN_CTX_get(ctx); 187 188 if (test == NULL) 189 goto err; 190 191 if (!BN_lshift(test, BN_value_one(), bits - 1)) 192 goto err; 193 194 for (;;) { 195 for (;;) { /* find q */ 196 int seed_is_random; 197 198 /* step 1 */ 199 if (!BN_GENCB_call(cb, 0, m++)) 200 goto err; 201 202 if (!seed_len || !seed_in) { 203 if (RAND_bytes(seed, qsize) <= 0) 204 goto err; 205 seed_is_random = 1; 206 } else { 207 seed_is_random = 0; 208 seed_len = 0; /* use random seed if 'seed_in' turns out to 209 * be bad */ 210 } 211 memcpy(buf, seed, qsize); 212 memcpy(buf2, seed, qsize); 213 /* precompute "SEED + 1" for step 7: */ 214 for (i = qsize - 1; i >= 0; i--) { 215 buf[i]++; 216 if (buf[i] != 0) 217 break; 218 } 219 220 /* step 2 */ 221 if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL)) 222 goto err; 223 if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL)) 224 goto err; 225 for (i = 0; i < qsize; i++) 226 md[i] ^= buf2[i]; 227 228 /* step 3 */ 229 md[0] |= 0x80; 230 md[qsize - 1] |= 0x01; 231 if (!BN_bin2bn(md, qsize, q)) 232 goto err; 233 234 /* step 4 */ 235 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx, 236 seed_is_random, cb); 237 if (r > 0) 238 break; 239 if (r != 0) 240 goto err; 241 242 /* do a callback call */ 243 /* step 5 */ 244 } 245 246 if (!BN_GENCB_call(cb, 2, 0)) 247 goto err; 248 if (!BN_GENCB_call(cb, 3, 0)) 249 goto err; 250 251 /* step 6 */ 252 counter = 0; 253 /* "offset = 2" */ 254 255 n = (bits - 1) / 160; 256 257 for (;;) { 258 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter)) 259 goto err; 260 261 /* step 7 */ 262 BN_zero(W); 263 /* now 'buf' contains "SEED + offset - 1" */ 264 for (k = 0; k <= n; k++) { 265 /* 266 * obtain "SEED + offset + k" by incrementing: 267 */ 268 for (i = qsize - 1; i >= 0; i--) { 269 buf[i]++; 270 if (buf[i] != 0) 271 break; 272 } 273 274 if (!EVP_Digest(buf, qsize, md, NULL, evpmd, NULL)) 275 goto err; 276 277 /* step 8 */ 278 if (!BN_bin2bn(md, qsize, r0)) 279 goto err; 280 if (!BN_lshift(r0, r0, (qsize << 3) * k)) 281 goto err; 282 if (!BN_add(W, W, r0)) 283 goto err; 284 } 285 286 /* more of step 8 */ 287 if (!BN_mask_bits(W, bits - 1)) 288 goto err; 289 if (!BN_copy(X, W)) 290 goto err; 291 if (!BN_add(X, X, test)) 292 goto err; 293 294 /* step 9 */ 295 if (!BN_lshift1(r0, q)) 296 goto err; 297 if (!BN_mod(c, X, r0, ctx)) 298 goto err; 299 if (!BN_sub(r0, c, BN_value_one())) 300 goto err; 301 if (!BN_sub(p, X, r0)) 302 goto err; 303 304 /* step 10 */ 305 if (BN_cmp(p, test) >= 0) { 306 /* step 11 */ 307 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb); 308 if (r > 0) 309 goto end; /* found it */ 310 if (r != 0) 311 goto err; 312 } 313 314 /* step 13 */ 315 counter++; 316 /* "offset = offset + n + 1" */ 317 318 /* step 14 */ 319 if (counter >= 4096) 320 break; 321 } 322 } 323 end: 324 if (!BN_GENCB_call(cb, 2, 1)) 325 goto err; 326 327 /* We now need to generate g */ 328 /* Set r0=(p-1)/q */ 329 if (!BN_sub(test, p, BN_value_one())) 330 goto err; 331 if (!BN_div(r0, NULL, test, q, ctx)) 332 goto err; 333 334 if (!BN_set_word(test, h)) 335 goto err; 336 if (!BN_MONT_CTX_set(mont, p, ctx)) 337 goto err; 338 339 for (;;) { 340 /* g=test^r0%p */ 341 if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont)) 342 goto err; 343 if (!BN_is_one(g)) 344 break; 345 if (!BN_add(test, test, BN_value_one())) 346 goto err; 347 h++; 348 } 349 350 if (!BN_GENCB_call(cb, 3, 1)) 351 goto err; 352 353 ok = 1; 354 err: 355 if (ok) { 356 if (ret->p) 357 BN_free(ret->p); 358 if (ret->q) 359 BN_free(ret->q); 360 if (ret->g) 361 BN_free(ret->g); 362 ret->p = BN_dup(p); 363 ret->q = BN_dup(q); 364 ret->g = BN_dup(g); 365 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) { 366 ok = 0; 367 goto err; 368 } 369 if (counter_ret != NULL) 370 *counter_ret = counter; 371 if (h_ret != NULL) 372 *h_ret = h; 373 if (seed_out) 374 memcpy(seed_out, seed, qsize); 375 } 376 if (ctx) { 377 BN_CTX_end(ctx); 378 BN_CTX_free(ctx); 379 } 380 if (mont != NULL) 381 BN_MONT_CTX_free(mont); 382 return ok; 383} 384 385# ifdef OPENSSL_FIPS 386# undef fips_dsa_builtin_paramgen2 387extern int fips_dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N, 388 const EVP_MD *evpmd, 389 const unsigned char *seed_in, 390 size_t seed_len, int idx, 391 unsigned char *seed_out, 392 int *counter_ret, unsigned long *h_ret, 393 BN_GENCB *cb); 394# endif 395 396/* 397 * This is a parameter generation algorithm for the DSA2 algorithm as 398 * described in FIPS 186-3. 399 */ 400 401int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N, 402 const EVP_MD *evpmd, const unsigned char *seed_in, 403 size_t seed_len, int idx, unsigned char *seed_out, 404 int *counter_ret, unsigned long *h_ret, 405 BN_GENCB *cb) 406{ 407 int ok = -1; 408 unsigned char *seed = NULL, *seed_tmp = NULL; 409 unsigned char md[EVP_MAX_MD_SIZE]; 410 int mdsize; 411 BIGNUM *r0, *W, *X, *c, *test; 412 BIGNUM *g = NULL, *q = NULL, *p = NULL; 413 BN_MONT_CTX *mont = NULL; 414 int i, k, n = 0, m = 0, qsize = N >> 3; 415 int counter = 0; 416 int r = 0; 417 BN_CTX *ctx = NULL; 418 EVP_MD_CTX mctx; 419 unsigned int h = 2; 420 421# ifdef OPENSSL_FIPS 422 423 if (FIPS_mode()) 424 return fips_dsa_builtin_paramgen2(ret, L, N, evpmd, 425 seed_in, seed_len, idx, 426 seed_out, counter_ret, h_ret, cb); 427# endif 428 429 EVP_MD_CTX_init(&mctx); 430 431 if (evpmd == NULL) { 432 if (N == 160) 433 evpmd = EVP_sha1(); 434 else if (N == 224) 435 evpmd = EVP_sha224(); 436 else 437 evpmd = EVP_sha256(); 438 } 439 440 mdsize = EVP_MD_size(evpmd); 441 /* If unverificable g generation only don't need seed */ 442 if (!ret->p || !ret->q || idx >= 0) { 443 if (seed_len == 0) 444 seed_len = mdsize; 445 446 seed = OPENSSL_malloc(seed_len); 447 448 if (seed_out) 449 seed_tmp = seed_out; 450 else 451 seed_tmp = OPENSSL_malloc(seed_len); 452 453 if (!seed || !seed_tmp) 454 goto err; 455 456 if (seed_in) 457 memcpy(seed, seed_in, seed_len); 458 459 } 460 461 if ((ctx = BN_CTX_new()) == NULL) 462 goto err; 463 464 if ((mont = BN_MONT_CTX_new()) == NULL) 465 goto err; 466 467 BN_CTX_start(ctx); 468 r0 = BN_CTX_get(ctx); 469 g = BN_CTX_get(ctx); 470 W = BN_CTX_get(ctx); 471 X = BN_CTX_get(ctx); 472 c = BN_CTX_get(ctx); 473 test = BN_CTX_get(ctx); 474 475 /* if p, q already supplied generate g only */ 476 if (ret->p && ret->q) { 477 p = ret->p; 478 q = ret->q; 479 if (idx >= 0) 480 memcpy(seed_tmp, seed, seed_len); 481 goto g_only; 482 } else { 483 p = BN_CTX_get(ctx); 484 q = BN_CTX_get(ctx); 485 } 486 487 if (!BN_lshift(test, BN_value_one(), L - 1)) 488 goto err; 489 for (;;) { 490 for (;;) { /* find q */ 491 unsigned char *pmd; 492 /* step 1 */ 493 if (!BN_GENCB_call(cb, 0, m++)) 494 goto err; 495 496 if (!seed_in) { 497 if (RAND_bytes(seed, seed_len) <= 0) 498 goto err; 499 } 500 /* step 2 */ 501 if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL)) 502 goto err; 503 /* Take least significant bits of md */ 504 if (mdsize > qsize) 505 pmd = md + mdsize - qsize; 506 else 507 pmd = md; 508 509 if (mdsize < qsize) 510 memset(md + mdsize, 0, qsize - mdsize); 511 512 /* step 3 */ 513 pmd[0] |= 0x80; 514 pmd[qsize - 1] |= 0x01; 515 if (!BN_bin2bn(pmd, qsize, q)) 516 goto err; 517 518 /* step 4 */ 519 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx, 520 seed_in ? 1 : 0, cb); 521 if (r > 0) 522 break; 523 if (r != 0) 524 goto err; 525 /* Provided seed didn't produce a prime: error */ 526 if (seed_in) { 527 ok = 0; 528 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_Q_NOT_PRIME); 529 goto err; 530 } 531 532 /* do a callback call */ 533 /* step 5 */ 534 } 535 /* Copy seed to seed_out before we mess with it */ 536 if (seed_out) 537 memcpy(seed_out, seed, seed_len); 538 539 if (!BN_GENCB_call(cb, 2, 0)) 540 goto err; 541 if (!BN_GENCB_call(cb, 3, 0)) 542 goto err; 543 544 /* step 6 */ 545 counter = 0; 546 /* "offset = 1" */ 547 548 n = (L - 1) / (mdsize << 3); 549 550 for (;;) { 551 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter)) 552 goto err; 553 554 /* step 7 */ 555 BN_zero(W); 556 /* now 'buf' contains "SEED + offset - 1" */ 557 for (k = 0; k <= n; k++) { 558 /* 559 * obtain "SEED + offset + k" by incrementing: 560 */ 561 for (i = seed_len - 1; i >= 0; i--) { 562 seed[i]++; 563 if (seed[i] != 0) 564 break; 565 } 566 567 if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL)) 568 goto err; 569 570 /* step 8 */ 571 if (!BN_bin2bn(md, mdsize, r0)) 572 goto err; 573 if (!BN_lshift(r0, r0, (mdsize << 3) * k)) 574 goto err; 575 if (!BN_add(W, W, r0)) 576 goto err; 577 } 578 579 /* more of step 8 */ 580 if (!BN_mask_bits(W, L - 1)) 581 goto err; 582 if (!BN_copy(X, W)) 583 goto err; 584 if (!BN_add(X, X, test)) 585 goto err; 586 587 /* step 9 */ 588 if (!BN_lshift1(r0, q)) 589 goto err; 590 if (!BN_mod(c, X, r0, ctx)) 591 goto err; 592 if (!BN_sub(r0, c, BN_value_one())) 593 goto err; 594 if (!BN_sub(p, X, r0)) 595 goto err; 596 597 /* step 10 */ 598 if (BN_cmp(p, test) >= 0) { 599 /* step 11 */ 600 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb); 601 if (r > 0) 602 goto end; /* found it */ 603 if (r != 0) 604 goto err; 605 } 606 607 /* step 13 */ 608 counter++; 609 /* "offset = offset + n + 1" */ 610 611 /* step 14 */ 612 if (counter >= (int)(4 * L)) 613 break; 614 } 615 if (seed_in) { 616 ok = 0; 617 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_INVALID_PARAMETERS); 618 goto err; 619 } 620 } 621 end: 622 if (!BN_GENCB_call(cb, 2, 1)) 623 goto err; 624 625 g_only: 626 627 /* We now need to generate g */ 628 /* Set r0=(p-1)/q */ 629 if (!BN_sub(test, p, BN_value_one())) 630 goto err; 631 if (!BN_div(r0, NULL, test, q, ctx)) 632 goto err; 633 634 if (idx < 0) { 635 if (!BN_set_word(test, h)) 636 goto err; 637 } else 638 h = 1; 639 if (!BN_MONT_CTX_set(mont, p, ctx)) 640 goto err; 641 642 for (;;) { 643 static const unsigned char ggen[4] = { 0x67, 0x67, 0x65, 0x6e }; 644 if (idx >= 0) { 645 md[0] = idx & 0xff; 646 md[1] = (h >> 8) & 0xff; 647 md[2] = h & 0xff; 648 if (!EVP_DigestInit_ex(&mctx, evpmd, NULL)) 649 goto err; 650 if (!EVP_DigestUpdate(&mctx, seed_tmp, seed_len)) 651 goto err; 652 if (!EVP_DigestUpdate(&mctx, ggen, sizeof(ggen))) 653 goto err; 654 if (!EVP_DigestUpdate(&mctx, md, 3)) 655 goto err; 656 if (!EVP_DigestFinal_ex(&mctx, md, NULL)) 657 goto err; 658 if (!BN_bin2bn(md, mdsize, test)) 659 goto err; 660 } 661 /* g=test^r0%p */ 662 if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont)) 663 goto err; 664 if (!BN_is_one(g)) 665 break; 666 if (idx < 0 && !BN_add(test, test, BN_value_one())) 667 goto err; 668 h++; 669 if (idx >= 0 && h > 0xffff) 670 goto err; 671 } 672 673 if (!BN_GENCB_call(cb, 3, 1)) 674 goto err; 675 676 ok = 1; 677 err: 678 if (ok == 1) { 679 if (p != ret->p) { 680 if (ret->p) 681 BN_free(ret->p); 682 ret->p = BN_dup(p); 683 } 684 if (q != ret->q) { 685 if (ret->q) 686 BN_free(ret->q); 687 ret->q = BN_dup(q); 688 } 689 if (ret->g) 690 BN_free(ret->g); 691 ret->g = BN_dup(g); 692 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) { 693 ok = -1; 694 goto err; 695 } 696 if (counter_ret != NULL) 697 *counter_ret = counter; 698 if (h_ret != NULL) 699 *h_ret = h; 700 } 701 if (seed) 702 OPENSSL_free(seed); 703 if (seed_out != seed_tmp) 704 OPENSSL_free(seed_tmp); 705 if (ctx) { 706 BN_CTX_end(ctx); 707 BN_CTX_free(ctx); 708 } 709 if (mont != NULL) 710 BN_MONT_CTX_free(mont); 711 EVP_MD_CTX_cleanup(&mctx); 712 return ok; 713} 714 715int dsa_paramgen_check_g(DSA *dsa) 716{ 717 BN_CTX *ctx; 718 BIGNUM *tmp; 719 BN_MONT_CTX *mont = NULL; 720 int rv = -1; 721 ctx = BN_CTX_new(); 722 if (!ctx) 723 return -1; 724 BN_CTX_start(ctx); 725 if (BN_cmp(dsa->g, BN_value_one()) <= 0) 726 return 0; 727 if (BN_cmp(dsa->g, dsa->p) >= 0) 728 return 0; 729 tmp = BN_CTX_get(ctx); 730 if (!tmp) 731 goto err; 732 if ((mont = BN_MONT_CTX_new()) == NULL) 733 goto err; 734 if (!BN_MONT_CTX_set(mont, dsa->p, ctx)) 735 goto err; 736 /* Work out g^q mod p */ 737 if (!BN_mod_exp_mont(tmp, dsa->g, dsa->q, dsa->p, ctx, mont)) 738 goto err; 739 if (!BN_cmp(tmp, BN_value_one())) 740 rv = 1; 741 else 742 rv = 0; 743 err: 744 BN_CTX_end(ctx); 745 if (mont) 746 BN_MONT_CTX_free(mont); 747 BN_CTX_free(ctx); 748 return rv; 749 750} 751#endif 752