1 /* 2 * Copyright 1995-2018 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_locl.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 if (ctx) 296 BN_CTX_end(ctx); 297 BN_CTX_free(ctx); 298 BN_MONT_CTX_free(mont); 299 return ok; 300 } 301 302 /* 303 * This is a parameter generation algorithm for the DSA2 algorithm as 304 * described in FIPS 186-3. 305 */ 306 307 int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N, 308 const EVP_MD *evpmd, const unsigned char *seed_in, 309 size_t seed_len, int idx, unsigned char *seed_out, 310 int *counter_ret, unsigned long *h_ret, 311 BN_GENCB *cb) 312 { 313 int ok = -1; 314 unsigned char *seed = NULL, *seed_tmp = NULL; 315 unsigned char md[EVP_MAX_MD_SIZE]; 316 int mdsize; 317 BIGNUM *r0, *W, *X, *c, *test; 318 BIGNUM *g = NULL, *q = NULL, *p = NULL; 319 BN_MONT_CTX *mont = NULL; 320 int i, k, n = 0, m = 0, qsize = N >> 3; 321 int counter = 0; 322 int r = 0; 323 BN_CTX *ctx = NULL; 324 EVP_MD_CTX *mctx = EVP_MD_CTX_new(); 325 unsigned int h = 2; 326 327 if (mctx == NULL) 328 goto err; 329 330 /* make sure L > N, otherwise we'll get trapped in an infinite loop */ 331 if (L <= N) { 332 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_INVALID_PARAMETERS); 333 goto err; 334 } 335 336 if (evpmd == NULL) { 337 if (N == 160) 338 evpmd = EVP_sha1(); 339 else if (N == 224) 340 evpmd = EVP_sha224(); 341 else 342 evpmd = EVP_sha256(); 343 } 344 345 mdsize = EVP_MD_size(evpmd); 346 /* If unverifiable g generation only don't need seed */ 347 if (!ret->p || !ret->q || idx >= 0) { 348 if (seed_len == 0) 349 seed_len = mdsize; 350 351 seed = OPENSSL_malloc(seed_len); 352 353 if (seed_out) 354 seed_tmp = seed_out; 355 else 356 seed_tmp = OPENSSL_malloc(seed_len); 357 358 if (seed == NULL || seed_tmp == NULL) 359 goto err; 360 361 if (seed_in) 362 memcpy(seed, seed_in, seed_len); 363 364 } 365 366 if ((ctx = BN_CTX_new()) == NULL) 367 goto err; 368 369 if ((mont = BN_MONT_CTX_new()) == NULL) 370 goto err; 371 372 BN_CTX_start(ctx); 373 r0 = BN_CTX_get(ctx); 374 g = BN_CTX_get(ctx); 375 W = BN_CTX_get(ctx); 376 X = BN_CTX_get(ctx); 377 c = BN_CTX_get(ctx); 378 test = BN_CTX_get(ctx); 379 if (test == NULL) 380 goto err; 381 382 /* if p, q already supplied generate g only */ 383 if (ret->p && ret->q) { 384 p = ret->p; 385 q = ret->q; 386 if (idx >= 0) 387 memcpy(seed_tmp, seed, seed_len); 388 goto g_only; 389 } else { 390 p = BN_CTX_get(ctx); 391 q = BN_CTX_get(ctx); 392 if (q == NULL) 393 goto err; 394 } 395 396 if (!BN_lshift(test, BN_value_one(), L - 1)) 397 goto err; 398 for (;;) { 399 for (;;) { /* find q */ 400 unsigned char *pmd; 401 /* step 1 */ 402 if (!BN_GENCB_call(cb, 0, m++)) 403 goto err; 404 405 if (!seed_in) { 406 if (RAND_bytes(seed, seed_len) <= 0) 407 goto err; 408 } 409 /* step 2 */ 410 if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL)) 411 goto err; 412 /* Take least significant bits of md */ 413 if (mdsize > qsize) 414 pmd = md + mdsize - qsize; 415 else 416 pmd = md; 417 418 if (mdsize < qsize) 419 memset(md + mdsize, 0, qsize - mdsize); 420 421 /* step 3 */ 422 pmd[0] |= 0x80; 423 pmd[qsize - 1] |= 0x01; 424 if (!BN_bin2bn(pmd, qsize, q)) 425 goto err; 426 427 /* step 4 */ 428 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx, 429 seed_in ? 1 : 0, cb); 430 if (r > 0) 431 break; 432 if (r != 0) 433 goto err; 434 /* Provided seed didn't produce a prime: error */ 435 if (seed_in) { 436 ok = 0; 437 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_Q_NOT_PRIME); 438 goto err; 439 } 440 441 /* do a callback call */ 442 /* step 5 */ 443 } 444 /* Copy seed to seed_out before we mess with it */ 445 if (seed_out) 446 memcpy(seed_out, seed, seed_len); 447 448 if (!BN_GENCB_call(cb, 2, 0)) 449 goto err; 450 if (!BN_GENCB_call(cb, 3, 0)) 451 goto err; 452 453 /* step 6 */ 454 counter = 0; 455 /* "offset = 1" */ 456 457 n = (L - 1) / (mdsize << 3); 458 459 for (;;) { 460 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter)) 461 goto err; 462 463 /* step 7 */ 464 BN_zero(W); 465 /* now 'buf' contains "SEED + offset - 1" */ 466 for (k = 0; k <= n; k++) { 467 /* 468 * obtain "SEED + offset + k" by incrementing: 469 */ 470 for (i = seed_len - 1; i >= 0; i--) { 471 seed[i]++; 472 if (seed[i] != 0) 473 break; 474 } 475 476 if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL)) 477 goto err; 478 479 /* step 8 */ 480 if (!BN_bin2bn(md, mdsize, r0)) 481 goto err; 482 if (!BN_lshift(r0, r0, (mdsize << 3) * k)) 483 goto err; 484 if (!BN_add(W, W, r0)) 485 goto err; 486 } 487 488 /* more of step 8 */ 489 if (!BN_mask_bits(W, L - 1)) 490 goto err; 491 if (!BN_copy(X, W)) 492 goto err; 493 if (!BN_add(X, X, test)) 494 goto err; 495 496 /* step 9 */ 497 if (!BN_lshift1(r0, q)) 498 goto err; 499 if (!BN_mod(c, X, r0, ctx)) 500 goto err; 501 if (!BN_sub(r0, c, BN_value_one())) 502 goto err; 503 if (!BN_sub(p, X, r0)) 504 goto err; 505 506 /* step 10 */ 507 if (BN_cmp(p, test) >= 0) { 508 /* step 11 */ 509 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb); 510 if (r > 0) 511 goto end; /* found it */ 512 if (r != 0) 513 goto err; 514 } 515 516 /* step 13 */ 517 counter++; 518 /* "offset = offset + n + 1" */ 519 520 /* step 14 */ 521 if (counter >= (int)(4 * L)) 522 break; 523 } 524 if (seed_in) { 525 ok = 0; 526 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_INVALID_PARAMETERS); 527 goto err; 528 } 529 } 530 end: 531 if (!BN_GENCB_call(cb, 2, 1)) 532 goto err; 533 534 g_only: 535 536 /* We now need to generate g */ 537 /* Set r0=(p-1)/q */ 538 if (!BN_sub(test, p, BN_value_one())) 539 goto err; 540 if (!BN_div(r0, NULL, test, q, ctx)) 541 goto err; 542 543 if (idx < 0) { 544 if (!BN_set_word(test, h)) 545 goto err; 546 } else 547 h = 1; 548 if (!BN_MONT_CTX_set(mont, p, ctx)) 549 goto err; 550 551 for (;;) { 552 static const unsigned char ggen[4] = { 0x67, 0x67, 0x65, 0x6e }; 553 if (idx >= 0) { 554 md[0] = idx & 0xff; 555 md[1] = (h >> 8) & 0xff; 556 md[2] = h & 0xff; 557 if (!EVP_DigestInit_ex(mctx, evpmd, NULL)) 558 goto err; 559 if (!EVP_DigestUpdate(mctx, seed_tmp, seed_len)) 560 goto err; 561 if (!EVP_DigestUpdate(mctx, ggen, sizeof(ggen))) 562 goto err; 563 if (!EVP_DigestUpdate(mctx, md, 3)) 564 goto err; 565 if (!EVP_DigestFinal_ex(mctx, md, NULL)) 566 goto err; 567 if (!BN_bin2bn(md, mdsize, test)) 568 goto err; 569 } 570 /* g=test^r0%p */ 571 if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont)) 572 goto err; 573 if (!BN_is_one(g)) 574 break; 575 if (idx < 0 && !BN_add(test, test, BN_value_one())) 576 goto err; 577 h++; 578 if (idx >= 0 && h > 0xffff) 579 goto err; 580 } 581 582 if (!BN_GENCB_call(cb, 3, 1)) 583 goto err; 584 585 ok = 1; 586 err: 587 if (ok == 1) { 588 if (p != ret->p) { 589 BN_free(ret->p); 590 ret->p = BN_dup(p); 591 } 592 if (q != ret->q) { 593 BN_free(ret->q); 594 ret->q = BN_dup(q); 595 } 596 BN_free(ret->g); 597 ret->g = BN_dup(g); 598 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) { 599 ok = -1; 600 goto err; 601 } 602 if (counter_ret != NULL) 603 *counter_ret = counter; 604 if (h_ret != NULL) 605 *h_ret = h; 606 } 607 OPENSSL_free(seed); 608 if (seed_out != seed_tmp) 609 OPENSSL_free(seed_tmp); 610 if (ctx) 611 BN_CTX_end(ctx); 612 BN_CTX_free(ctx); 613 BN_MONT_CTX_free(mont); 614 EVP_MD_CTX_free(mctx); 615 return ok; 616 } 617