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 (!BN_lshift(test, BN_value_one(), bits - 1)) 189 goto err; 190 191 for (;;) { 192 for (;;) { /* find q */ 193 int seed_is_random; 194 195 /* step 1 */ 196 if (!BN_GENCB_call(cb, 0, m++)) 197 goto err; 198 199 if (!seed_len || !seed_in) { 200 if (RAND_pseudo_bytes(seed, qsize) < 0) 201 goto err; 202 seed_is_random = 1; 203 } else { 204 seed_is_random = 0; 205 seed_len = 0; /* use random seed if 'seed_in' turns out to 206 * be bad */ 207 } 208 memcpy(buf, seed, qsize); 209 memcpy(buf2, seed, qsize); 210 /* precompute "SEED + 1" for step 7: */ 211 for (i = qsize - 1; i >= 0; i--) { 212 buf[i]++; 213 if (buf[i] != 0) 214 break; 215 } 216 217 /* step 2 */ 218 if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL)) 219 goto err; 220 if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL)) 221 goto err; 222 for (i = 0; i < qsize; i++) 223 md[i] ^= buf2[i]; 224 225 /* step 3 */ 226 md[0] |= 0x80; 227 md[qsize - 1] |= 0x01; 228 if (!BN_bin2bn(md, qsize, q)) 229 goto err; 230 231 /* step 4 */ 232 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx, 233 seed_is_random, cb); 234 if (r > 0) 235 break; 236 if (r != 0) 237 goto err; 238 239 /* do a callback call */ 240 /* step 5 */ 241 } 242 243 if (!BN_GENCB_call(cb, 2, 0)) 244 goto err; 245 if (!BN_GENCB_call(cb, 3, 0)) 246 goto err; 247 248 /* step 6 */ 249 counter = 0; 250 /* "offset = 2" */ 251 252 n = (bits - 1) / 160; 253 254 for (;;) { 255 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter)) 256 goto err; 257 258 /* step 7 */ 259 BN_zero(W); 260 /* now 'buf' contains "SEED + offset - 1" */ 261 for (k = 0; k <= n; k++) { 262 /* 263 * obtain "SEED + offset + k" by incrementing: 264 */ 265 for (i = qsize - 1; i >= 0; i--) { 266 buf[i]++; 267 if (buf[i] != 0) 268 break; 269 } 270 271 if (!EVP_Digest(buf, qsize, md, NULL, evpmd, NULL)) 272 goto err; 273 274 /* step 8 */ 275 if (!BN_bin2bn(md, qsize, r0)) 276 goto err; 277 if (!BN_lshift(r0, r0, (qsize << 3) * k)) 278 goto err; 279 if (!BN_add(W, W, r0)) 280 goto err; 281 } 282 283 /* more of step 8 */ 284 if (!BN_mask_bits(W, bits - 1)) 285 goto err; 286 if (!BN_copy(X, W)) 287 goto err; 288 if (!BN_add(X, X, test)) 289 goto err; 290 291 /* step 9 */ 292 if (!BN_lshift1(r0, q)) 293 goto err; 294 if (!BN_mod(c, X, r0, ctx)) 295 goto err; 296 if (!BN_sub(r0, c, BN_value_one())) 297 goto err; 298 if (!BN_sub(p, X, r0)) 299 goto err; 300 301 /* step 10 */ 302 if (BN_cmp(p, test) >= 0) { 303 /* step 11 */ 304 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb); 305 if (r > 0) 306 goto end; /* found it */ 307 if (r != 0) 308 goto err; 309 } 310 311 /* step 13 */ 312 counter++; 313 /* "offset = offset + n + 1" */ 314 315 /* step 14 */ 316 if (counter >= 4096) 317 break; 318 } 319 } 320 end: 321 if (!BN_GENCB_call(cb, 2, 1)) 322 goto err; 323 324 /* We now need to generate g */ 325 /* Set r0=(p-1)/q */ 326 if (!BN_sub(test, p, BN_value_one())) 327 goto err; 328 if (!BN_div(r0, NULL, test, q, ctx)) 329 goto err; 330 331 if (!BN_set_word(test, h)) 332 goto err; 333 if (!BN_MONT_CTX_set(mont, p, ctx)) 334 goto err; 335 336 for (;;) { 337 /* g=test^r0%p */ 338 if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont)) 339 goto err; 340 if (!BN_is_one(g)) 341 break; 342 if (!BN_add(test, test, BN_value_one())) 343 goto err; 344 h++; 345 } 346 347 if (!BN_GENCB_call(cb, 3, 1)) 348 goto err; 349 350 ok = 1; 351 err: 352 if (ok) { 353 if (ret->p) 354 BN_free(ret->p); 355 if (ret->q) 356 BN_free(ret->q); 357 if (ret->g) 358 BN_free(ret->g); 359 ret->p = BN_dup(p); 360 ret->q = BN_dup(q); 361 ret->g = BN_dup(g); 362 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) { 363 ok = 0; 364 goto err; 365 } 366 if (counter_ret != NULL) 367 *counter_ret = counter; 368 if (h_ret != NULL) 369 *h_ret = h; 370 if (seed_out) 371 memcpy(seed_out, seed, qsize); 372 } 373 if (ctx) { 374 BN_CTX_end(ctx); 375 BN_CTX_free(ctx); 376 } 377 if (mont != NULL) 378 BN_MONT_CTX_free(mont); 379 return ok; 380} 381 382# ifdef OPENSSL_FIPS 383# undef fips_dsa_builtin_paramgen2 384extern int fips_dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N, 385 const EVP_MD *evpmd, 386 const unsigned char *seed_in, 387 size_t seed_len, int idx, 388 unsigned char *seed_out, 389 int *counter_ret, unsigned long *h_ret, 390 BN_GENCB *cb); 391# endif 392 393/* 394 * This is a parameter generation algorithm for the DSA2 algorithm as 395 * described in FIPS 186-3. 396 */ 397 398int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N, 399 const EVP_MD *evpmd, const unsigned char *seed_in, 400 size_t seed_len, int idx, unsigned char *seed_out, 401 int *counter_ret, unsigned long *h_ret, 402 BN_GENCB *cb) 403{ 404 int ok = -1; 405 unsigned char *seed = NULL, *seed_tmp = NULL; 406 unsigned char md[EVP_MAX_MD_SIZE]; 407 int mdsize; 408 BIGNUM *r0, *W, *X, *c, *test; 409 BIGNUM *g = NULL, *q = NULL, *p = NULL; 410 BN_MONT_CTX *mont = NULL; 411 int i, k, n = 0, m = 0, qsize = N >> 3; 412 int counter = 0; 413 int r = 0; 414 BN_CTX *ctx = NULL; 415 EVP_MD_CTX mctx; 416 unsigned int h = 2; 417 418# ifdef OPENSSL_FIPS 419 420 if (FIPS_mode()) 421 return fips_dsa_builtin_paramgen2(ret, L, N, evpmd, 422 seed_in, seed_len, idx, 423 seed_out, counter_ret, h_ret, cb); 424# endif 425 426 EVP_MD_CTX_init(&mctx); 427 428 if (evpmd == NULL) { 429 if (N == 160) 430 evpmd = EVP_sha1(); 431 else if (N == 224) 432 evpmd = EVP_sha224(); 433 else 434 evpmd = EVP_sha256(); 435 } 436 437 mdsize = EVP_MD_size(evpmd); 438 /* If unverificable g generation only don't need seed */ 439 if (!ret->p || !ret->q || idx >= 0) { 440 if (seed_len == 0) 441 seed_len = mdsize; 442 443 seed = OPENSSL_malloc(seed_len); 444 445 if (seed_out) 446 seed_tmp = seed_out; 447 else 448 seed_tmp = OPENSSL_malloc(seed_len); 449 450 if (!seed || !seed_tmp) 451 goto err; 452 453 if (seed_in) 454 memcpy(seed, seed_in, seed_len); 455 456 } 457 458 if ((ctx = BN_CTX_new()) == NULL) 459 goto err; 460 461 if ((mont = BN_MONT_CTX_new()) == NULL) 462 goto err; 463 464 BN_CTX_start(ctx); 465 r0 = BN_CTX_get(ctx); 466 g = BN_CTX_get(ctx); 467 W = BN_CTX_get(ctx); 468 X = BN_CTX_get(ctx); 469 c = BN_CTX_get(ctx); 470 test = BN_CTX_get(ctx); 471 472 /* if p, q already supplied generate g only */ 473 if (ret->p && ret->q) { 474 p = ret->p; 475 q = ret->q; 476 if (idx >= 0) 477 memcpy(seed_tmp, seed, seed_len); 478 goto g_only; 479 } else { 480 p = BN_CTX_get(ctx); 481 q = BN_CTX_get(ctx); 482 } 483 484 if (!BN_lshift(test, BN_value_one(), L - 1)) 485 goto err; 486 for (;;) { 487 for (;;) { /* find q */ 488 unsigned char *pmd; 489 /* step 1 */ 490 if (!BN_GENCB_call(cb, 0, m++)) 491 goto err; 492 493 if (!seed_in) { 494 if (RAND_pseudo_bytes(seed, seed_len) < 0) 495 goto err; 496 } 497 /* step 2 */ 498 if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL)) 499 goto err; 500 /* Take least significant bits of md */ 501 if (mdsize > qsize) 502 pmd = md + mdsize - qsize; 503 else 504 pmd = md; 505 506 if (mdsize < qsize) 507 memset(md + mdsize, 0, qsize - mdsize); 508 509 /* step 3 */ 510 pmd[0] |= 0x80; 511 pmd[qsize - 1] |= 0x01; 512 if (!BN_bin2bn(pmd, qsize, q)) 513 goto err; 514 515 /* step 4 */ 516 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx, 517 seed_in ? 1 : 0, cb); 518 if (r > 0) 519 break; 520 if (r != 0) 521 goto err; 522 /* Provided seed didn't produce a prime: error */ 523 if (seed_in) { 524 ok = 0; 525 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_Q_NOT_PRIME); 526 goto err; 527 } 528 529 /* do a callback call */ 530 /* step 5 */ 531 } 532 /* Copy seed to seed_out before we mess with it */ 533 if (seed_out) 534 memcpy(seed_out, seed, seed_len); 535 536 if (!BN_GENCB_call(cb, 2, 0)) 537 goto err; 538 if (!BN_GENCB_call(cb, 3, 0)) 539 goto err; 540 541 /* step 6 */ 542 counter = 0; 543 /* "offset = 1" */ 544 545 n = (L - 1) / (mdsize << 3); 546 547 for (;;) { 548 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter)) 549 goto err; 550 551 /* step 7 */ 552 BN_zero(W); 553 /* now 'buf' contains "SEED + offset - 1" */ 554 for (k = 0; k <= n; k++) { 555 /* 556 * obtain "SEED + offset + k" by incrementing: 557 */ 558 for (i = seed_len - 1; i >= 0; i--) { 559 seed[i]++; 560 if (seed[i] != 0) 561 break; 562 } 563 564 if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL)) 565 goto err; 566 567 /* step 8 */ 568 if (!BN_bin2bn(md, mdsize, r0)) 569 goto err; 570 if (!BN_lshift(r0, r0, (mdsize << 3) * k)) 571 goto err; 572 if (!BN_add(W, W, r0)) 573 goto err; 574 } 575 576 /* more of step 8 */ 577 if (!BN_mask_bits(W, L - 1)) 578 goto err; 579 if (!BN_copy(X, W)) 580 goto err; 581 if (!BN_add(X, X, test)) 582 goto err; 583 584 /* step 9 */ 585 if (!BN_lshift1(r0, q)) 586 goto err; 587 if (!BN_mod(c, X, r0, ctx)) 588 goto err; 589 if (!BN_sub(r0, c, BN_value_one())) 590 goto err; 591 if (!BN_sub(p, X, r0)) 592 goto err; 593 594 /* step 10 */ 595 if (BN_cmp(p, test) >= 0) { 596 /* step 11 */ 597 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb); 598 if (r > 0) 599 goto end; /* found it */ 600 if (r != 0) 601 goto err; 602 } 603 604 /* step 13 */ 605 counter++; 606 /* "offset = offset + n + 1" */ 607 608 /* step 14 */ 609 if (counter >= (int)(4 * L)) 610 break; 611 } 612 if (seed_in) { 613 ok = 0; 614 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_INVALID_PARAMETERS); 615 goto err; 616 } 617 } 618 end: 619 if (!BN_GENCB_call(cb, 2, 1)) 620 goto err; 621 622 g_only: 623 624 /* We now need to generate g */ 625 /* Set r0=(p-1)/q */ 626 if (!BN_sub(test, p, BN_value_one())) 627 goto err; 628 if (!BN_div(r0, NULL, test, q, ctx)) 629 goto err; 630 631 if (idx < 0) { 632 if (!BN_set_word(test, h)) 633 goto err; 634 } else 635 h = 1; 636 if (!BN_MONT_CTX_set(mont, p, ctx)) 637 goto err; 638 639 for (;;) { 640 static const unsigned char ggen[4] = { 0x67, 0x67, 0x65, 0x6e }; 641 if (idx >= 0) { 642 md[0] = idx & 0xff; 643 md[1] = (h >> 8) & 0xff; 644 md[2] = h & 0xff; 645 if (!EVP_DigestInit_ex(&mctx, evpmd, NULL)) 646 goto err; 647 if (!EVP_DigestUpdate(&mctx, seed_tmp, seed_len)) 648 goto err; 649 if (!EVP_DigestUpdate(&mctx, ggen, sizeof(ggen))) 650 goto err; 651 if (!EVP_DigestUpdate(&mctx, md, 3)) 652 goto err; 653 if (!EVP_DigestFinal_ex(&mctx, md, NULL)) 654 goto err; 655 if (!BN_bin2bn(md, mdsize, test)) 656 goto err; 657 } 658 /* g=test^r0%p */ 659 if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont)) 660 goto err; 661 if (!BN_is_one(g)) 662 break; 663 if (idx < 0 && !BN_add(test, test, BN_value_one())) 664 goto err; 665 h++; 666 if (idx >= 0 && h > 0xffff) 667 goto err; 668 } 669 670 if (!BN_GENCB_call(cb, 3, 1)) 671 goto err; 672 673 ok = 1; 674 err: 675 if (ok == 1) { 676 if (p != ret->p) { 677 if (ret->p) 678 BN_free(ret->p); 679 ret->p = BN_dup(p); 680 } 681 if (q != ret->q) { 682 if (ret->q) 683 BN_free(ret->q); 684 ret->q = BN_dup(q); 685 } 686 if (ret->g) 687 BN_free(ret->g); 688 ret->g = BN_dup(g); 689 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) { 690 ok = -1; 691 goto err; 692 } 693 if (counter_ret != NULL) 694 *counter_ret = counter; 695 if (h_ret != NULL) 696 *h_ret = h; 697 } 698 if (seed) 699 OPENSSL_free(seed); 700 if (seed_out != seed_tmp) 701 OPENSSL_free(seed_tmp); 702 if (ctx) { 703 BN_CTX_end(ctx); 704 BN_CTX_free(ctx); 705 } 706 if (mont != NULL) 707 BN_MONT_CTX_free(mont); 708 EVP_MD_CTX_cleanup(&mctx); 709 return ok; 710} 711 712int dsa_paramgen_check_g(DSA *dsa) 713{ 714 BN_CTX *ctx; 715 BIGNUM *tmp; 716 BN_MONT_CTX *mont = NULL; 717 int rv = -1; 718 ctx = BN_CTX_new(); 719 if (!ctx) 720 return -1; 721 BN_CTX_start(ctx); 722 if (BN_cmp(dsa->g, BN_value_one()) <= 0) 723 return 0; 724 if (BN_cmp(dsa->g, dsa->p) >= 0) 725 return 0; 726 tmp = BN_CTX_get(ctx); 727 if (!tmp) 728 goto err; 729 if ((mont = BN_MONT_CTX_new()) == NULL) 730 goto err; 731 if (!BN_MONT_CTX_set(mont, dsa->p, ctx)) 732 goto err; 733 /* Work out g^q mod p */ 734 if (!BN_mod_exp_mont(tmp, dsa->g, dsa->q, dsa->p, ctx, mont)) 735 goto err; 736 if (!BN_cmp(tmp, BN_value_one())) 737 rv = 1; 738 else 739 rv = 0; 740 err: 741 BN_CTX_end(ctx); 742 if (mont) 743 BN_MONT_CTX_free(mont); 744 BN_CTX_free(ctx); 745 return rv; 746 747} 748#endif 749