crypto/dsa/dsa_gen.c

   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 /* Parameter generation follows the original release of FIPS PUB 186,
  63  * Appendix 2.2 (i.e. use SHA as defined in FIPS PUB 180) */
  64 #define HASH    EVP_sha()
  65 #else
  66 /* Parameter generation follows the updated Appendix 2.2 for FIPS PUB 186,
  67  * also Appendix 2.2 of FIPS PUB 186-1 (i.e. use SHA as defined in
  68  * FIPS PUB 180-1) */
  69 #define HASH    EVP_sha1()
  70 #endif
  71
  72 #include <openssl/opensslconf.h> /* To see if OPENSSL_NO_SHA is defined */
  73
  74 #ifndef OPENSSL_NO_SHA
  75
  76 #define OPENSSL_FIPSAPI
  77
  78 #include <stdio.h>
  79 #include "cryptlib.h"
  80 #include <openssl/evp.h>
  81 #include <openssl/bn.h>
  82 #include <openssl/rand.h>
  83 #include <openssl/sha.h>
  84 #ifdef OPENSSL_FIPS
  85 #include <openssl/fips.h>
  86 #include <openssl/fips_rand.h>
  87 #endif
  88
  89 #include "dsa_locl.h"
  90
  91 int DSA_generate_parameters_ex(DSA *ret, int bits,
  92                 const unsigned char *seed_in, int seed_len,
  93                 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
  94         {
  95         if(ret->meth->dsa_paramgen)
  96                 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
  97                                 counter_ret, h_ret, cb);
  98         else
  99                 {
 100                 const EVP_MD *evpmd;
 101                 size_t qbits = bits >= 2048 ? 256 : 160;
 102
 103                 if (bits >= 2048)
 104                         {
 105                         qbits = 256;
 106                         evpmd = EVP_sha256();
 107                         }
 108                 else
 109                         {
 110                         qbits = 160;
 111                         evpmd = EVP_sha1();
 112                         }
 113
 114                 return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
 115                         seed_in, seed_len, NULL, counter_ret, h_ret, cb);
 116                 }
 117         }
 118
 119 int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
 120         const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
 121         unsigned char *seed_out,
 122         int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
 123         {
 124         int ok=0;
 125         unsigned char seed[SHA256_DIGEST_LENGTH];
 126         unsigned char md[SHA256_DIGEST_LENGTH];
 127         unsigned char buf[SHA256_DIGEST_LENGTH],buf2[SHA256_DIGEST_LENGTH];
 128         BIGNUM *r0,*W,*X,*c,*test;
 129         BIGNUM *g=NULL,*q=NULL,*p=NULL;
 130         BN_MONT_CTX *mont=NULL;
 131         int i, k, n=0, m=0, qsize = qbits >> 3;
 132         int counter=0;
 133         int r=0;
 134         BN_CTX *ctx=NULL;
 135         unsigned int h=2;
 136
 137 #ifdef OPENSSL_FIPS
 138         if(FIPS_selftest_failed())
 139             {
 140             FIPSerr(FIPS_F_DSA_BUILTIN_PARAMGEN, FIPS_R_FIPS_SELFTEST_FAILED);
 141             goto err;
 142             }
 143
 144         if (FIPS_module_mode() && !(ret->flags & DSA_FLAG_NON_FIPS_ALLOW)
 145                         && (bits < OPENSSL_DSA_FIPS_MIN_MODULUS_BITS))
 146                 {
 147                 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN, DSA_R_KEY_SIZE_TOO_SMALL);
 148                 goto err;
 149                 }
 150 #endif
 151
 152         if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
 153             qsize != SHA256_DIGEST_LENGTH)
 154                 /* invalid q size */
 155                 return 0;
 156
 157         if (evpmd == NULL)
 158                 /* use SHA1 as default */
 159                 evpmd = EVP_sha1();
 160
 161         if (bits < 512)
 162                 bits = 512;
 163
 164         bits = (bits+63)/64*64;
 165
 166         /* NB: seed_len == 0 is special case: copy generated seed to
 167          * seed_in if it is not NULL.
 168          */
 169         if (seed_len && (seed_len < (size_t)qsize))
 170                 seed_in = NULL;         /* seed buffer too small -- ignore */
 171         if (seed_len > (size_t)qsize)
 172                 seed_len = qsize;       /* App. 2.2 of FIPS PUB 186 allows larger SEED,
 173                                          * but our internal buffers are restricted to 160 bits*/
 174         if (seed_in != NULL)
 175                 memcpy(seed, seed_in, seed_len);
 176
 177         if ((ctx=BN_CTX_new()) == NULL)
 178                 goto err;
 179
 180         if ((mont=BN_MONT_CTX_new()) == NULL)
 181                 goto err;
 182
 183         BN_CTX_start(ctx);
 184         r0 = BN_CTX_get(ctx);
 185         g = BN_CTX_get(ctx);
 186         W = BN_CTX_get(ctx);
 187         q = BN_CTX_get(ctx);
 188         X = BN_CTX_get(ctx);
 189         c = BN_CTX_get(ctx);
 190         p = BN_CTX_get(ctx);
 191         test = BN_CTX_get(ctx);
 192
 193         if (!BN_lshift(test,BN_value_one(),bits-1))
 194                 goto err;
 195
 196         for (;;)
 197                 {
 198                 for (;;) /* find q */
 199                         {
 200                         int seed_is_random;
 201
 202                         /* step 1 */
 203                         if(!BN_GENCB_call(cb, 0, m++))
 204                                 goto err;
 205
 206                         if (!seed_len)
 207                                 {
 208                                 if (RAND_pseudo_bytes(seed, qsize) < 0)
 209                                         goto err;
 210                                 seed_is_random = 1;
 211                                 }
 212                         else
 213                                 {
 214                                 seed_is_random = 0;
 215                                 seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/
 216                                 }
 217                         memcpy(buf , seed, qsize);
 218                         memcpy(buf2, seed, qsize);
 219                         /* precompute "SEED + 1" for step 7: */
 220                         for (i = qsize-1; i >= 0; i--)
 221                                 {
 222                                 buf[i]++;
 223                                 if (buf[i] != 0)
 224                                         break;
 225                                 }
 226
 227                         /* step 2 */
 228                         if (!EVP_Digest(seed, qsize, md,   NULL, evpmd, NULL))
 229                                 goto err;
 230                         if (!EVP_Digest(buf,  qsize, buf2, NULL, evpmd, NULL))
 231                                 goto err;
 232                         for (i = 0; i < qsize; i++)
 233                                 md[i]^=buf2[i];
 234
 235                         /* step 3 */
 236                         md[0] |= 0x80;
 237                         md[qsize-1] |= 0x01;
 238                         if (!BN_bin2bn(md, qsize, q))
 239                                 goto err;
 240
 241                         /* step 4 */
 242                         r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
 243                                         seed_is_random, cb);
 244                         if (r > 0)
 245                                 break;
 246                         if (r != 0)
 247                                 goto err;
 248
 249                         /* do a callback call */
 250                         /* step 5 */
 251                         }
 252
 253                 if(!BN_GENCB_call(cb, 2, 0)) goto err;
 254                 if(!BN_GENCB_call(cb, 3, 0)) goto err;
 255
 256                 /* step 6 */
 257                 counter=0;
 258                 /* "offset = 2" */
 259
 260                 n=(bits-1)/160;
 261
 262                 for (;;)
 263                         {
 264                         if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
 265                                 goto err;
 266
 267                         /* step 7 */
 268                         BN_zero(W);
 269                         /* now 'buf' contains "SEED + offset - 1" */
 270                         for (k=0; k<=n; k++)
 271                                 {
 272                                 /* obtain "SEED + offset + k" by incrementing: */
 273                                 for (i = qsize-1; i >= 0; i--)
 274                                         {
 275                                         buf[i]++;
 276                                         if (buf[i] != 0)
 277                                                 break;
 278                                         }
 279
 280                                 if (!EVP_Digest(buf, qsize, md ,NULL, evpmd,
 281                                                                         NULL))
 282                                         goto err;
 283
 284                                 /* step 8 */
 285                                 if (!BN_bin2bn(md, qsize, r0))
 286                                         goto err;
 287                                 if (!BN_lshift(r0,r0,(qsize << 3)*k)) goto err;
 288                                 if (!BN_add(W,W,r0)) goto err;
 289                                 }
 290
 291                         /* more of step 8 */
 292                         if (!BN_mask_bits(W,bits-1)) goto err;
 293                         if (!BN_copy(X,W)) goto err;
 294                         if (!BN_add(X,X,test)) goto err;
 295
 296                         /* step 9 */
 297                         if (!BN_lshift1(r0,q)) goto err;
 298                         if (!BN_mod(c,X,r0,ctx)) goto err;
 299                         if (!BN_sub(r0,c,BN_value_one())) goto err;
 300                         if (!BN_sub(p,X,r0)) goto err;
 301
 302                         /* step 10 */
 303                         if (BN_cmp(p,test) >= 0)
 304                                 {
 305                                 /* step 11 */
 306                                 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
 307                                                 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) break;
 320                         }
 321                 }
 322 end:
 323         if(!BN_GENCB_call(cb, 2, 1))
 324                 goto err;
 325
 326         /* We now need to generate g */
 327         /* Set r0=(p-1)/q */
 328         if (!BN_sub(test,p,BN_value_one())) goto err;
 329         if (!BN_div(r0,NULL,test,q,ctx)) goto err;
 330
 331         if (!BN_set_word(test,h)) goto err;
 332         if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
 333
 334         for (;;)
 335                 {
 336                 /* g=test^r0%p */
 337                 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
 338                 if (!BN_is_one(g)) break;
 339                 if (!BN_add(test,test,BN_value_one())) goto err;
 340                 h++;
 341                 }
 342
 343         if(!BN_GENCB_call(cb, 3, 1))
 344                 goto err;
 345
 346         ok=1;
 347 err:
 348         if (ok)
 349                 {
 350                 if(ret->p) BN_free(ret->p);
 351                 if(ret->q) BN_free(ret->q);
 352                 if(ret->g) BN_free(ret->g);
 353                 ret->p=BN_dup(p);
 354                 ret->q=BN_dup(q);
 355                 ret->g=BN_dup(g);
 356                 if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
 357                         {
 358                         ok=0;
 359                         goto err;
 360                         }
 361                 if (counter_ret != NULL) *counter_ret=counter;
 362                 if (h_ret != NULL) *h_ret=h;
 363                 if (seed_out)
 364                         memcpy(seed_out, seed, qsize);
 365                 }
 366         if(ctx)
 367                 {
 368                 BN_CTX_end(ctx);
 369                 BN_CTX_free(ctx);
 370                 }
 371         if (mont != NULL) BN_MONT_CTX_free(mont);
 372         return ok;
 373         }
 374
 375 #ifdef OPENSSL_FIPS
 376
 377 /* Security strength of parameter values for (L,N): see FIPS186-3 4.2
 378  * and SP800-131A
 379  */
 380
 381
 382 static int fips_ffc_strength(size_t L, size_t N)
 383         {
 384         if (L >= 15360 && N >= 512)
 385                 return 256;
 386         if (L >= 7680 && N >= 384)
 387                 return 192;
 388         if (L >= 3072 && N >= 256)
 389                 return 128;
 390         if (L >= 2048 && N >= 224)
 391                 return 112;
 392         if (L >= 1024 && N >= 160)
 393                 return  80;
 394         return 0;
 395         }
 396
 397 /* Valid DSA2 parameters from FIPS 186-3 */
 398
 399 static int dsa2_valid_parameters(size_t L, size_t N)
 400         {
 401         if (L == 1024 && N == 160)
 402                 return 80;
 403         if (L == 2048 && N == 224)
 404                 return 112;
 405         if (L == 2048 && N == 256)
 406                 return 112;
 407         if (L == 3072 && N == 256)
 408                 return 112;
 409         return 0;
 410         }
 411
 412 int fips_check_dsa_prng(DSA *dsa, size_t L, size_t N)
 413         {
 414         int strength;
 415         if (!FIPS_module_mode())
 416                 return 1;
 417
 418         if (dsa->flags & (DSA_FLAG_NON_FIPS_ALLOW|DSA_FLAG_FIPS_CHECKED))
 419                 return 1;
 420
 421         if (!L || !N)
 422                 {
 423                 L = BN_num_bits(dsa->p);
 424                 N = BN_num_bits(dsa->q);
 425                 }
 426         if (!dsa2_valid_parameters(L, N))
 427                 {
 428                 FIPSerr(FIPS_F_FIPS_CHECK_DSA_PRNG, FIPS_R_INVALID_PARAMETERS);
 429                 return 0;
 430                 }
 431
 432         strength = fips_ffc_strength(L, N);
 433
 434         if (!strength)
 435                 {
 436                 FIPSerr(FIPS_F_FIPS_CHECK_DSA_PRNG,FIPS_R_KEY_TOO_SHORT);
 437                 return 0;
 438                 }
 439
 440         if (FIPS_rand_strength() >= strength)
 441                 return 1;
 442
 443         FIPSerr(FIPS_F_FIPS_CHECK_DSA_PRNG,FIPS_R_PRNG_STRENGTH_TOO_LOW);
 444         return 0;
 445
 446         }
 447 #endif /* OPENSSL_FIPS */
 448
 449 /* This is a parameter generation algorithm for the DSA2 algorithm as
 450  * described in FIPS 186-3.
 451  */
 452
 453 int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N,
 454         const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
 455         int idx, unsigned char *seed_out,
 456         int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
 457         {
 458         int ok=-1;
 459         unsigned char *seed = NULL, *seed_tmp = NULL;
 460         unsigned char md[EVP_MAX_MD_SIZE];
 461         int mdsize;
 462         BIGNUM *r0,*W,*X,*c,*test;
 463         BIGNUM *g=NULL,*q=NULL,*p=NULL;
 464         BN_MONT_CTX *mont=NULL;
 465         int i, k, n=0, m=0, qsize = N >> 3;
 466         int counter=0;
 467         int r=0;
 468         BN_CTX *ctx=NULL;
 469         EVP_MD_CTX mctx;
 470         unsigned int h=2;
 471
 472         EVP_MD_CTX_init(&mctx);
 473
 474 #ifdef OPENSSL_FIPS
 475         if(FIPS_selftest_failed())
 476             {
 477             FIPSerr(FIPS_F_DSA_BUILTIN_PARAMGEN2,
 478                     FIPS_R_FIPS_SELFTEST_FAILED);
 479             goto err;
 480             }
 481
 482         if (!fips_check_dsa_prng(ret, L, N))
 483                 goto err;
 484 #endif
 485
 486         if (evpmd == NULL)
 487                 {
 488                 if (N == 160)
 489                         evpmd = EVP_sha1();
 490                 else if (N == 224)
 491                         evpmd = EVP_sha224();
 492                 else
 493                         evpmd = EVP_sha256();
 494                 }
 495
 496         mdsize = M_EVP_MD_size(evpmd);
 497         /* If unverificable g generation only don't need seed */
 498         if (!ret->p || !ret->q || idx >= 0)
 499                 {
 500                 if (seed_len == 0)
 501                         seed_len = mdsize;
 502
 503                 seed = OPENSSL_malloc(seed_len);
 504
 505                 if (seed_out)
 506                         seed_tmp = seed_out;
 507                 else
 508                         seed_tmp = OPENSSL_malloc(seed_len);
 509
 510                 if (!seed || !seed_tmp)
 511                         goto err;
 512
 513                 if (seed_in)
 514                         memcpy(seed, seed_in, seed_len);
 515
 516                 }
 517
 518         if ((ctx=BN_CTX_new()) == NULL)
 519                 goto err;
 520
 521         if ((mont=BN_MONT_CTX_new()) == NULL)
 522                 goto err;
 523
 524         BN_CTX_start(ctx);
 525         r0 = BN_CTX_get(ctx);
 526         g = BN_CTX_get(ctx);
 527         W = BN_CTX_get(ctx);
 528         X = BN_CTX_get(ctx);
 529         c = BN_CTX_get(ctx);
 530         test = BN_CTX_get(ctx);
 531
 532         /* if p, q already supplied generate g only */
 533         if (ret->p && ret->q)
 534                 {
 535                 p = ret->p;
 536                 q = ret->q;
 537                 if (idx >= 0)
 538                         memcpy(seed_tmp, seed, seed_len);
 539                 goto g_only;
 540                 }
 541         else
 542                 {
 543                 p = BN_CTX_get(ctx);
 544                 q = BN_CTX_get(ctx);
 545                 }
 546
 547         if (!BN_lshift(test,BN_value_one(),L-1))
 548                 goto err;
 549         for (;;)
 550                 {
 551                 for (;;) /* find q */
 552                         {
 553                         unsigned char *pmd;
 554                         /* step 1 */
 555                         if(!BN_GENCB_call(cb, 0, m++))
 556                                 goto err;
 557
 558                         if (!seed_in)
 559                                 {
 560                                 if (RAND_pseudo_bytes(seed, seed_len) < 0)
 561                                         goto err;
 562                                 }
 563                         /* step 2 */
 564                         if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL))
 565                                 goto err;
 566                         /* Take least significant bits of md */
 567                         if (mdsize > qsize)
 568                                 pmd = md + mdsize - qsize;
 569                         else
 570                                 pmd = md;
 571
 572                         if (mdsize < qsize)
 573                                 memset(md + mdsize, 0, qsize - mdsize);
 574
 575                         /* step 3 */
 576                         pmd[0] |= 0x80;
 577                         pmd[qsize-1] |= 0x01;
 578                         if (!BN_bin2bn(pmd, qsize, q))
 579                                 goto err;
 580
 581                         /* step 4 */
 582                         r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
 583                                         seed_in ? 1 : 0, cb);
 584                         if (r > 0)
 585                                 break;
 586                         if (r != 0)
 587                                 goto err;
 588                         /* Provided seed didn't produce a prime: error */
 589                         if (seed_in)
 590                                 {
 591                                 ok = 0;
 592                                 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_Q_NOT_PRIME);
 593                                 goto err;
 594                                 }
 595
 596                         /* do a callback call */
 597                         /* step 5 */
 598                         }
 599                 /* Copy seed to seed_out before we mess with it */
 600                 if (seed_out)
 601                         memcpy(seed_out, seed, seed_len);
 602
 603                 if(!BN_GENCB_call(cb, 2, 0)) goto err;
 604                 if(!BN_GENCB_call(cb, 3, 0)) goto err;
 605
 606                 /* step 6 */
 607                 counter=0;
 608                 /* "offset = 1" */
 609
 610                 n=(L-1)/(mdsize << 3);
 611
 612                 for (;;)
 613                         {
 614                         if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
 615                                 goto err;
 616
 617                         /* step 7 */
 618                         BN_zero(W);
 619                         /* now 'buf' contains "SEED + offset - 1" */
 620                         for (k=0; k<=n; k++)
 621                                 {
 622                                 /* obtain "SEED + offset + k" by incrementing: */
 623                                 for (i = seed_len-1; i >= 0; i--)
 624                                         {
 625                                         seed[i]++;
 626                                         if (seed[i] != 0)
 627                                                 break;
 628                                         }
 629
 630                                 if (!EVP_Digest(seed, seed_len, md ,NULL, evpmd,
 631                                                                         NULL))
 632                                         goto err;
 633
 634                                 /* step 8 */
 635                                 if (!BN_bin2bn(md, mdsize, r0))
 636                                         goto err;
 637                                 if (!BN_lshift(r0,r0,(mdsize << 3)*k)) goto err;
 638                                 if (!BN_add(W,W,r0)) goto err;
 639                                 }
 640
 641                         /* more of step 8 */
 642                         if (!BN_mask_bits(W,L-1)) goto err;
 643                         if (!BN_copy(X,W)) goto err;
 644                         if (!BN_add(X,X,test)) goto err;
 645
 646                         /* step 9 */
 647                         if (!BN_lshift1(r0,q)) goto err;
 648                         if (!BN_mod(c,X,r0,ctx)) goto err;
 649                         if (!BN_sub(r0,c,BN_value_one())) goto err;
 650                         if (!BN_sub(p,X,r0)) goto err;
 651
 652                         /* step 10 */
 653                         if (BN_cmp(p,test) >= 0)
 654                                 {
 655                                 /* step 11 */
 656                                 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
 657                                                 ctx, 1, cb);
 658                                 if (r > 0)
 659                                                 goto end; /* found it */
 660                                 if (r != 0)
 661                                         goto err;
 662                                 }
 663
 664                         /* step 13 */
 665                         counter++;
 666                         /* "offset = offset + n + 1" */
 667
 668                         /* step 14 */
 669                         if (counter >= 4096) break;
 670                         }
 671                 }
 672 end:
 673         if(!BN_GENCB_call(cb, 2, 1))
 674                 goto err;
 675
 676         g_only:
 677
 678         /* We now need to generate g */
 679         /* Set r0=(p-1)/q */
 680         if (!BN_sub(test,p,BN_value_one())) goto err;
 681         if (!BN_div(r0,NULL,test,q,ctx)) goto err;
 682
 683         if (idx < 0)
 684                 {
 685                 if (!BN_set_word(test,h))
 686                         goto err;
 687                 }
 688         else
 689                 h = 1;
 690         if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
 691
 692         for (;;)
 693                 {
 694                 static const unsigned char ggen[4] = {0x67,0x67,0x65,0x6e};
 695                 if (idx >= 0)
 696                         {
 697                         md[0] = idx & 0xff;
 698                         md[1] = (h >> 8) & 0xff;
 699                         md[2] = h & 0xff;
 700                         if (!EVP_DigestInit_ex(&mctx, evpmd, NULL))
 701                                 goto err;
 702                         if (!EVP_DigestUpdate(&mctx, seed_tmp, seed_len))
 703                                 goto err;
 704                         if (!EVP_DigestUpdate(&mctx, ggen, sizeof(ggen)))
 705                                 goto err;
 706                         if (!EVP_DigestUpdate(&mctx, md, 3))
 707                                 goto err;
 708                         if (!EVP_DigestFinal_ex(&mctx, md, NULL))
 709                                 goto err;
 710                         if (!BN_bin2bn(md, mdsize, test))
 711                                 goto err;
 712                         }
 713                 /* g=test^r0%p */
 714                 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
 715                 if (!BN_is_one(g)) break;
 716                 if (idx < 0 && !BN_add(test,test,BN_value_one())) goto err;
 717                 h++;
 718                 if ( idx >= 0 && h > 0xffff)
 719                         goto err;
 720                 }
 721
 722         if(!BN_GENCB_call(cb, 3, 1))
 723                 goto err;
 724
 725         ok=1;
 726 err:
 727         if (ok == 1)
 728                 {
 729                 if (p != ret->p)
 730                         {
 731                         if(ret->p) BN_free(ret->p);
 732                         ret->p=BN_dup(p);
 733                         }
 734                 if (q != ret->q)
 735                         {
 736                         if(ret->q) BN_free(ret->q);
 737                         ret->q=BN_dup(q);
 738                         }
 739                 if(ret->g) BN_free(ret->g);
 740                 ret->g=BN_dup(g);
 741                 if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
 742                         {
 743                         ok=-1;
 744                         goto err;
 745                         }
 746                 if (counter_ret != NULL) *counter_ret=counter;
 747                 if (h_ret != NULL) *h_ret=h;
 748                 }
 749         if (seed)
 750                 OPENSSL_free(seed);
 751         if (seed_out != seed_tmp)
 752                 OPENSSL_free(seed_tmp);
 753         if(ctx)
 754                 {
 755                 BN_CTX_end(ctx);
 756                 BN_CTX_free(ctx);
 757                 }
 758         if (mont != NULL) BN_MONT_CTX_free(mont);
 759         EVP_MD_CTX_cleanup(&mctx);
 760         return ok;
 761         }
 762
 763 int dsa_paramgen_check_g(DSA *dsa)
 764         {
 765         BN_CTX *ctx;
 766         BIGNUM *tmp;
 767         BN_MONT_CTX *mont = NULL;
 768         int rv = -1;
 769         ctx = BN_CTX_new();
 770         if (!ctx)
 771                 return -1;
 772         BN_CTX_start(ctx);
 773         if (BN_cmp(dsa->g, BN_value_one()) <= 0)
 774                 return 0;
 775         if (BN_cmp(dsa->g, dsa->p) >= 0)
 776                 return 0;
 777         tmp = BN_CTX_get(ctx);
 778         if (!tmp)
 779                 goto err;
 780         if ((mont=BN_MONT_CTX_new()) == NULL)
 781                 goto err;
 782         if (!BN_MONT_CTX_set(mont,dsa->p,ctx))
 783                 goto err;
 784         /* Work out g^q mod p */
 785         if (!BN_mod_exp_mont(tmp,dsa->g,dsa->q, dsa->p, ctx, mont))
 786                 goto err;
 787         if (!BN_cmp(tmp, BN_value_one()))
 788                 rv = 1;
 789         else
 790                 rv = 0;
 791         err:
 792         BN_CTX_end(ctx);
 793         if (mont)
 794                 BN_MONT_CTX_free(mont);
 795         BN_CTX_free(ctx);
 796         return rv;
 797
 798         }
 799
 800 #endif