1 /* 2 * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the OpenSSL license (the "License"). You may not use 5 * this file except in compliance with the License. You can obtain a copy 6 * in the file LICENSE in the source distribution or at 7 * https://www.openssl.org/source/license.html 8 */ 9 10 /* 11 * Parameter generation follows the updated Appendix 2.2 for FIPS PUB 186, 12 * also Appendix 2.2 of FIPS PUB 186-1 (i.e. use SHA as defined in FIPS PUB 13 * 180-1) 14 */ 15 #define xxxHASH EVP_sha1() 16 17 #include <openssl/opensslconf.h> 18 #include <stdio.h> 19 #include "internal/cryptlib.h" 20 #include <openssl/evp.h> 21 #include <openssl/bn.h> 22 #include <openssl/rand.h> 23 #include <openssl/sha.h> 24 #include "dsa_local.h" 25 26 int DSA_generate_parameters_ex(DSA *ret, int bits, 27 const unsigned char *seed_in, int seed_len, 28 int *counter_ret, unsigned long *h_ret, 29 BN_GENCB *cb) 30 { 31 if (ret->meth->dsa_paramgen) 32 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len, 33 counter_ret, h_ret, cb); 34 else { 35 const EVP_MD *evpmd = bits >= 2048 ? EVP_sha256() : EVP_sha1(); 36 size_t qbits = EVP_MD_size(evpmd) * 8; 37 38 return dsa_builtin_paramgen(ret, bits, qbits, evpmd, 39 seed_in, seed_len, NULL, counter_ret, 40 h_ret, cb); 41 } 42 } 43 44 int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits, 45 const EVP_MD *evpmd, const unsigned char *seed_in, 46 size_t seed_len, unsigned char *seed_out, 47 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb) 48 { 49 int ok = 0; 50 unsigned char seed[SHA256_DIGEST_LENGTH]; 51 unsigned char md[SHA256_DIGEST_LENGTH]; 52 unsigned char buf[SHA256_DIGEST_LENGTH], buf2[SHA256_DIGEST_LENGTH]; 53 BIGNUM *r0, *W, *X, *c, *test; 54 BIGNUM *g = NULL, *q = NULL, *p = NULL; 55 BN_MONT_CTX *mont = NULL; 56 int i, k, n = 0, m = 0, qsize = qbits >> 3; 57 int counter = 0; 58 int r = 0; 59 BN_CTX *ctx = NULL; 60 unsigned int h = 2; 61 62 if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH && 63 qsize != SHA256_DIGEST_LENGTH) 64 /* invalid q size */ 65 return 0; 66 67 if (evpmd == NULL) { 68 if (qsize == SHA_DIGEST_LENGTH) 69 evpmd = EVP_sha1(); 70 else if (qsize == SHA224_DIGEST_LENGTH) 71 evpmd = EVP_sha224(); 72 else 73 evpmd = EVP_sha256(); 74 } else { 75 qsize = EVP_MD_size(evpmd); 76 } 77 78 if (bits < 512) 79 bits = 512; 80 81 bits = (bits + 63) / 64 * 64; 82 83 if (seed_in != NULL) { 84 if (seed_len < (size_t)qsize) { 85 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN, DSA_R_SEED_LEN_SMALL); 86 return 0; 87 } 88 if (seed_len > (size_t)qsize) { 89 /* Only consume as much seed as is expected. */ 90 seed_len = qsize; 91 } 92 memcpy(seed, seed_in, seed_len); 93 } 94 95 if ((mont = BN_MONT_CTX_new()) == NULL) 96 goto err; 97 98 if ((ctx = BN_CTX_new()) == NULL) 99 goto err; 100 101 BN_CTX_start(ctx); 102 103 r0 = BN_CTX_get(ctx); 104 g = BN_CTX_get(ctx); 105 W = BN_CTX_get(ctx); 106 q = BN_CTX_get(ctx); 107 X = BN_CTX_get(ctx); 108 c = BN_CTX_get(ctx); 109 p = BN_CTX_get(ctx); 110 test = BN_CTX_get(ctx); 111 112 if (test == NULL) 113 goto err; 114 115 if (!BN_lshift(test, BN_value_one(), bits - 1)) 116 goto err; 117 118 for (;;) { 119 for (;;) { /* find q */ 120 int use_random_seed = (seed_in == NULL); 121 122 /* step 1 */ 123 if (!BN_GENCB_call(cb, 0, m++)) 124 goto err; 125 126 if (use_random_seed) { 127 if (RAND_bytes(seed, qsize) <= 0) 128 goto err; 129 } else { 130 /* If we come back through, use random seed next time. */ 131 seed_in = NULL; 132 } 133 memcpy(buf, seed, qsize); 134 memcpy(buf2, seed, qsize); 135 /* precompute "SEED + 1" for step 7: */ 136 for (i = qsize - 1; i >= 0; i--) { 137 buf[i]++; 138 if (buf[i] != 0) 139 break; 140 } 141 142 /* step 2 */ 143 if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL)) 144 goto err; 145 if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL)) 146 goto err; 147 for (i = 0; i < qsize; i++) 148 md[i] ^= buf2[i]; 149 150 /* step 3 */ 151 md[0] |= 0x80; 152 md[qsize - 1] |= 0x01; 153 if (!BN_bin2bn(md, qsize, q)) 154 goto err; 155 156 /* step 4 */ 157 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx, 158 use_random_seed, cb); 159 if (r > 0) 160 break; 161 if (r != 0) 162 goto err; 163 164 /* do a callback call */ 165 /* step 5 */ 166 } 167 168 if (!BN_GENCB_call(cb, 2, 0)) 169 goto err; 170 if (!BN_GENCB_call(cb, 3, 0)) 171 goto err; 172 173 /* step 6 */ 174 counter = 0; 175 /* "offset = 2" */ 176 177 n = (bits - 1) / 160; 178 179 for (;;) { 180 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter)) 181 goto err; 182 183 /* step 7 */ 184 BN_zero(W); 185 /* now 'buf' contains "SEED + offset - 1" */ 186 for (k = 0; k <= n; k++) { 187 /* 188 * obtain "SEED + offset + k" by incrementing: 189 */ 190 for (i = qsize - 1; i >= 0; i--) { 191 buf[i]++; 192 if (buf[i] != 0) 193 break; 194 } 195 196 if (!EVP_Digest(buf, qsize, md, NULL, evpmd, NULL)) 197 goto err; 198 199 /* step 8 */ 200 if (!BN_bin2bn(md, qsize, r0)) 201 goto err; 202 if (!BN_lshift(r0, r0, (qsize << 3) * k)) 203 goto err; 204 if (!BN_add(W, W, r0)) 205 goto err; 206 } 207 208 /* more of step 8 */ 209 if (!BN_mask_bits(W, bits - 1)) 210 goto err; 211 if (!BN_copy(X, W)) 212 goto err; 213 if (!BN_add(X, X, test)) 214 goto err; 215 216 /* step 9 */ 217 if (!BN_lshift1(r0, q)) 218 goto err; 219 if (!BN_mod(c, X, r0, ctx)) 220 goto err; 221 if (!BN_sub(r0, c, BN_value_one())) 222 goto err; 223 if (!BN_sub(p, X, r0)) 224 goto err; 225 226 /* step 10 */ 227 if (BN_cmp(p, test) >= 0) { 228 /* step 11 */ 229 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb); 230 if (r > 0) 231 goto end; /* found it */ 232 if (r != 0) 233 goto err; 234 } 235 236 /* step 13 */ 237 counter++; 238 /* "offset = offset + n + 1" */ 239 240 /* step 14 */ 241 if (counter >= 4096) 242 break; 243 } 244 } 245 end: 246 if (!BN_GENCB_call(cb, 2, 1)) 247 goto err; 248 249 /* We now need to generate g */ 250 /* Set r0=(p-1)/q */ 251 if (!BN_sub(test, p, BN_value_one())) 252 goto err; 253 if (!BN_div(r0, NULL, test, q, ctx)) 254 goto err; 255 256 if (!BN_set_word(test, h)) 257 goto err; 258 if (!BN_MONT_CTX_set(mont, p, ctx)) 259 goto err; 260 261 for (;;) { 262 /* g=test^r0%p */ 263 if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont)) 264 goto err; 265 if (!BN_is_one(g)) 266 break; 267 if (!BN_add(test, test, BN_value_one())) 268 goto err; 269 h++; 270 } 271 272 if (!BN_GENCB_call(cb, 3, 1)) 273 goto err; 274 275 ok = 1; 276 err: 277 if (ok) { 278 BN_free(ret->p); 279 BN_free(ret->q); 280 BN_free(ret->g); 281 ret->p = BN_dup(p); 282 ret->q = BN_dup(q); 283 ret->g = BN_dup(g); 284 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) { 285 ok = 0; 286 goto err; 287 } 288 if (counter_ret != NULL) 289 *counter_ret = counter; 290 if (h_ret != NULL) 291 *h_ret = h; 292 if (seed_out) 293 memcpy(seed_out, seed, qsize); 294 } 295 BN_CTX_end(ctx); 296 BN_CTX_free(ctx); 297 BN_MONT_CTX_free(mont); 298 return ok; 299 } 300 301 /* 302 * This is a parameter generation algorithm for the DSA2 algorithm as 303 * described in FIPS 186-3. 304 */ 305 306 int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N, 307 const EVP_MD *evpmd, const unsigned char *seed_in, 308 size_t seed_len, int idx, unsigned char *seed_out, 309 int *counter_ret, unsigned long *h_ret, 310 BN_GENCB *cb) 311 { 312 int ok = -1; 313 unsigned char *seed = NULL, *seed_tmp = NULL; 314 unsigned char md[EVP_MAX_MD_SIZE]; 315 int mdsize; 316 BIGNUM *r0, *W, *X, *c, *test; 317 BIGNUM *g = NULL, *q = NULL, *p = NULL; 318 BN_MONT_CTX *mont = NULL; 319 int i, k, n = 0, m = 0, qsize = N >> 3; 320 int counter = 0; 321 int r = 0; 322 BN_CTX *ctx = NULL; 323 EVP_MD_CTX *mctx = EVP_MD_CTX_new(); 324 unsigned int h = 2; 325 326 if (mctx == NULL) 327 goto err; 328 329 /* make sure L > N, otherwise we'll get trapped in an infinite loop */ 330 if (L <= N) { 331 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_INVALID_PARAMETERS); 332 goto err; 333 } 334 335 if (evpmd == NULL) { 336 if (N == 160) 337 evpmd = EVP_sha1(); 338 else if (N == 224) 339 evpmd = EVP_sha224(); 340 else 341 evpmd = EVP_sha256(); 342 } 343 344 mdsize = EVP_MD_size(evpmd); 345 /* If unverifiable g generation only don't need seed */ 346 if (!ret->p || !ret->q || idx >= 0) { 347 if (seed_len == 0) 348 seed_len = mdsize; 349 350 seed = OPENSSL_malloc(seed_len); 351 352 if (seed_out) 353 seed_tmp = seed_out; 354 else 355 seed_tmp = OPENSSL_malloc(seed_len); 356 357 if (seed == NULL || seed_tmp == NULL) 358 goto err; 359 360 if (seed_in) 361 memcpy(seed, seed_in, seed_len); 362 363 } 364 365 if ((ctx = BN_CTX_new()) == NULL) 366 goto err; 367 368 if ((mont = BN_MONT_CTX_new()) == NULL) 369 goto err; 370 371 BN_CTX_start(ctx); 372 r0 = BN_CTX_get(ctx); 373 g = BN_CTX_get(ctx); 374 W = BN_CTX_get(ctx); 375 X = BN_CTX_get(ctx); 376 c = BN_CTX_get(ctx); 377 test = BN_CTX_get(ctx); 378 if (test == NULL) 379 goto err; 380 381 /* if p, q already supplied generate g only */ 382 if (ret->p && ret->q) { 383 p = ret->p; 384 q = ret->q; 385 if (idx >= 0) 386 memcpy(seed_tmp, seed, seed_len); 387 goto g_only; 388 } else { 389 p = BN_CTX_get(ctx); 390 q = BN_CTX_get(ctx); 391 if (q == NULL) 392 goto err; 393 } 394 395 if (!BN_lshift(test, BN_value_one(), L - 1)) 396 goto err; 397 for (;;) { 398 for (;;) { /* find q */ 399 unsigned char *pmd; 400 /* step 1 */ 401 if (!BN_GENCB_call(cb, 0, m++)) 402 goto err; 403 404 if (!seed_in) { 405 if (RAND_bytes(seed, seed_len) <= 0) 406 goto err; 407 } 408 /* step 2 */ 409 if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL)) 410 goto err; 411 /* Take least significant bits of md */ 412 if (mdsize > qsize) 413 pmd = md + mdsize - qsize; 414 else 415 pmd = md; 416 417 if (mdsize < qsize) 418 memset(md + mdsize, 0, qsize - mdsize); 419 420 /* step 3 */ 421 pmd[0] |= 0x80; 422 pmd[qsize - 1] |= 0x01; 423 if (!BN_bin2bn(pmd, qsize, q)) 424 goto err; 425 426 /* step 4 */ 427 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx, 428 seed_in ? 1 : 0, cb); 429 if (r > 0) 430 break; 431 if (r != 0) 432 goto err; 433 /* Provided seed didn't produce a prime: error */ 434 if (seed_in) { 435 ok = 0; 436 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_Q_NOT_PRIME); 437 goto err; 438 } 439 440 /* do a callback call */ 441 /* step 5 */ 442 } 443 /* Copy seed to seed_out before we mess with it */ 444 if (seed_out) 445 memcpy(seed_out, seed, seed_len); 446 447 if (!BN_GENCB_call(cb, 2, 0)) 448 goto err; 449 if (!BN_GENCB_call(cb, 3, 0)) 450 goto err; 451 452 /* step 6 */ 453 counter = 0; 454 /* "offset = 1" */ 455 456 n = (L - 1) / (mdsize << 3); 457 458 for (;;) { 459 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter)) 460 goto err; 461 462 /* step 7 */ 463 BN_zero(W); 464 /* now 'buf' contains "SEED + offset - 1" */ 465 for (k = 0; k <= n; k++) { 466 /* 467 * obtain "SEED + offset + k" by incrementing: 468 */ 469 for (i = seed_len - 1; i >= 0; i--) { 470 seed[i]++; 471 if (seed[i] != 0) 472 break; 473 } 474 475 if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL)) 476 goto err; 477 478 /* step 8 */ 479 if (!BN_bin2bn(md, mdsize, r0)) 480 goto err; 481 if (!BN_lshift(r0, r0, (mdsize << 3) * k)) 482 goto err; 483 if (!BN_add(W, W, r0)) 484 goto err; 485 } 486 487 /* more of step 8 */ 488 if (!BN_mask_bits(W, L - 1)) 489 goto err; 490 if (!BN_copy(X, W)) 491 goto err; 492 if (!BN_add(X, X, test)) 493 goto err; 494 495 /* step 9 */ 496 if (!BN_lshift1(r0, q)) 497 goto err; 498 if (!BN_mod(c, X, r0, ctx)) 499 goto err; 500 if (!BN_sub(r0, c, BN_value_one())) 501 goto err; 502 if (!BN_sub(p, X, r0)) 503 goto err; 504 505 /* step 10 */ 506 if (BN_cmp(p, test) >= 0) { 507 /* step 11 */ 508 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb); 509 if (r > 0) 510 goto end; /* found it */ 511 if (r != 0) 512 goto err; 513 } 514 515 /* step 13 */ 516 counter++; 517 /* "offset = offset + n + 1" */ 518 519 /* step 14 */ 520 if (counter >= (int)(4 * L)) 521 break; 522 } 523 if (seed_in) { 524 ok = 0; 525 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_INVALID_PARAMETERS); 526 goto err; 527 } 528 } 529 end: 530 if (!BN_GENCB_call(cb, 2, 1)) 531 goto err; 532 533 g_only: 534 535 /* We now need to generate g */ 536 /* Set r0=(p-1)/q */ 537 if (!BN_sub(test, p, BN_value_one())) 538 goto err; 539 if (!BN_div(r0, NULL, test, q, ctx)) 540 goto err; 541 542 if (idx < 0) { 543 if (!BN_set_word(test, h)) 544 goto err; 545 } else 546 h = 1; 547 if (!BN_MONT_CTX_set(mont, p, ctx)) 548 goto err; 549 550 for (;;) { 551 static const unsigned char ggen[4] = { 0x67, 0x67, 0x65, 0x6e }; 552 if (idx >= 0) { 553 md[0] = idx & 0xff; 554 md[1] = (h >> 8) & 0xff; 555 md[2] = h & 0xff; 556 if (!EVP_DigestInit_ex(mctx, evpmd, NULL)) 557 goto err; 558 if (!EVP_DigestUpdate(mctx, seed_tmp, seed_len)) 559 goto err; 560 if (!EVP_DigestUpdate(mctx, ggen, sizeof(ggen))) 561 goto err; 562 if (!EVP_DigestUpdate(mctx, md, 3)) 563 goto err; 564 if (!EVP_DigestFinal_ex(mctx, md, NULL)) 565 goto err; 566 if (!BN_bin2bn(md, mdsize, test)) 567 goto err; 568 } 569 /* g=test^r0%p */ 570 if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont)) 571 goto err; 572 if (!BN_is_one(g)) 573 break; 574 if (idx < 0 && !BN_add(test, test, BN_value_one())) 575 goto err; 576 h++; 577 if (idx >= 0 && h > 0xffff) 578 goto err; 579 } 580 581 if (!BN_GENCB_call(cb, 3, 1)) 582 goto err; 583 584 ok = 1; 585 err: 586 if (ok == 1) { 587 if (p != ret->p) { 588 BN_free(ret->p); 589 ret->p = BN_dup(p); 590 } 591 if (q != ret->q) { 592 BN_free(ret->q); 593 ret->q = BN_dup(q); 594 } 595 BN_free(ret->g); 596 ret->g = BN_dup(g); 597 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) { 598 ok = -1; 599 goto err; 600 } 601 if (counter_ret != NULL) 602 *counter_ret = counter; 603 if (h_ret != NULL) 604 *h_ret = h; 605 } 606 OPENSSL_free(seed); 607 if (seed_out != seed_tmp) 608 OPENSSL_free(seed_tmp); 609 BN_CTX_end(ctx); 610 BN_CTX_free(ctx); 611 BN_MONT_CTX_free(mont); 612 EVP_MD_CTX_free(mctx); 613 return ok; 614 } 615