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_FIPSEVP
  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 #endif
  87
  88 #include "dsa_locl.h"
  89
  90 int DSA_generate_parameters_ex(DSA *ret, int bits,
  91                 const unsigned char *seed_in, int seed_len,
  92                 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
  93         {
  94         if(ret->meth->dsa_paramgen)
  95                 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
  96                                 counter_ret, h_ret, cb);
  97         else
  98                 {
  99                 const EVP_MD *evpmd;
 100                 size_t qbits = bits >= 2048 ? 256 : 160;
 101
 102                 if (bits >= 2048)
 103                         {
 104                         qbits = 256;
 105                         evpmd = EVP_sha256();
 106                         }
 107                 else
 108                         {
 109                         qbits = 160;
 110                         evpmd = EVP_sha1();
 111                         }
 112
 113                 return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
 114                         seed_in, seed_len, NULL, counter_ret, h_ret, cb);
 115                 }
 116         }
 117
 118 int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
 119         const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
 120         unsigned char *seed_out,
 121         int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
 122         {
 123         int ok=0;
 124         unsigned char seed[SHA256_DIGEST_LENGTH];
 125         unsigned char md[SHA256_DIGEST_LENGTH];
 126         unsigned char buf[SHA256_DIGEST_LENGTH],buf2[SHA256_DIGEST_LENGTH];
 127         BIGNUM *r0,*W,*X,*c,*test;
 128         BIGNUM *g=NULL,*q=NULL,*p=NULL;
 129         BN_MONT_CTX *mont=NULL;
 130         int i, k, n=0, m=0, qsize = qbits >> 3;
 131         int counter=0;
 132         int r=0;
 133         BN_CTX *ctx=NULL;
 134         unsigned int h=2;
 135
 136 #ifdef OPENSSL_FIPS
 137         if(FIPS_selftest_failed())
 138             {
 139             FIPSerr(FIPS_F_DSA_BUILTIN_PARAMGEN,
 140                     FIPS_R_FIPS_SELFTEST_FAILED);
 141             goto err;
 142             }
 143
 144         if (FIPS_mode() && (bits < OPENSSL_DSA_FIPS_MIN_MODULUS_BITS))
 145                 {
 146                 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN, DSA_R_KEY_SIZE_TOO_SMALL);
 147                 goto err;
 148                 }
 149 #endif
 150
 151         if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
 152             qsize != SHA256_DIGEST_LENGTH)
 153                 /* invalid q size */
 154                 return 0;
 155
 156         if (evpmd == NULL)
 157                 /* use SHA1 as default */
 158                 evpmd = EVP_sha1();
 159
 160         if (bits < 512)
 161                 bits = 512;
 162
 163         bits = (bits+63)/64*64;
 164
 165         /* NB: seed_len == 0 is special case: copy generated seed to
 166          * seed_in if it is not NULL.
 167          */
 168         if (seed_len && (seed_len < (size_t)qsize))
 169                 seed_in = NULL;         /* seed buffer too small -- ignore */
 170         if (seed_len > (size_t)qsize)
 171                 seed_len = qsize;       /* App. 2.2 of FIPS PUB 186 allows larger SEED,
 172                                          * but our internal buffers are restricted to 160 bits*/
 173         if (seed_in != NULL)
 174                 memcpy(seed, seed_in, seed_len);
 175
 176         if ((ctx=BN_CTX_new()) == NULL)
 177                 goto err;
 178
 179         if ((mont=BN_MONT_CTX_new()) == NULL)
 180                 goto err;
 181
 182         BN_CTX_start(ctx);
 183         r0 = BN_CTX_get(ctx);
 184         g = BN_CTX_get(ctx);
 185         W = BN_CTX_get(ctx);
 186         q = BN_CTX_get(ctx);
 187         X = BN_CTX_get(ctx);
 188         c = BN_CTX_get(ctx);
 189         p = BN_CTX_get(ctx);
 190         test = BN_CTX_get(ctx);
 191
 192         if (!BN_lshift(test,BN_value_one(),bits-1))
 193                 goto err;
 194
 195         for (;;)
 196                 {
 197                 for (;;) /* find q */
 198                         {
 199                         int seed_is_random;
 200
 201                         /* step 1 */
 202                         if(!BN_GENCB_call(cb, 0, m++))
 203                                 goto err;
 204
 205                         if (!seed_len)
 206                                 {
 207                                 RAND_pseudo_bytes(seed, qsize);
 208                                 seed_is_random = 1;
 209                                 }
 210                         else
 211                                 {
 212                                 seed_is_random = 0;
 213                                 seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/
 214                                 }
 215                         memcpy(buf , seed, qsize);
 216                         memcpy(buf2, seed, qsize);
 217                         /* precompute "SEED + 1" for step 7: */
 218                         for (i = qsize-1; i >= 0; i--)
 219                                 {
 220                                 buf[i]++;
 221                                 if (buf[i] != 0)
 222                                         break;
 223                                 }
 224
 225                         /* step 2 */
 226                         if (!EVP_Digest(seed, qsize, md,   NULL, evpmd, NULL))
 227                                 goto err;
 228                         if (!EVP_Digest(buf,  qsize, buf2, NULL, evpmd, NULL))
 229                                 goto err;
 230                         for (i = 0; i < qsize; i++)
 231                                 md[i]^=buf2[i];
 232
 233                         /* step 3 */
 234                         md[0] |= 0x80;
 235                         md[qsize-1] |= 0x01;
 236                         if (!BN_bin2bn(md, qsize, q))
 237                                 goto err;
 238
 239                         /* step 4 */
 240                         r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
 241                                         seed_is_random, cb);
 242                         if (r > 0)
 243                                 break;
 244                         if (r != 0)
 245                                 goto err;
 246
 247                         /* do a callback call */
 248                         /* step 5 */
 249                         }
 250
 251                 if(!BN_GENCB_call(cb, 2, 0)) goto err;
 252                 if(!BN_GENCB_call(cb, 3, 0)) goto err;
 253
 254                 /* step 6 */
 255                 counter=0;
 256                 /* "offset = 2" */
 257
 258                 n=(bits-1)/160;
 259
 260                 for (;;)
 261                         {
 262                         if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
 263                                 goto err;
 264
 265                         /* step 7 */
 266                         BN_zero(W);
 267                         /* now 'buf' contains "SEED + offset - 1" */
 268                         for (k=0; k<=n; k++)
 269                                 {
 270                                 /* obtain "SEED + offset + k" by incrementing: */
 271                                 for (i = qsize-1; i >= 0; i--)
 272                                         {
 273                                         buf[i]++;
 274                                         if (buf[i] != 0)
 275                                                 break;
 276                                         }
 277
 278                                 if (!EVP_Digest(buf, qsize, md ,NULL, evpmd,
 279                                                                         NULL))
 280                                         goto err;
 281
 282                                 /* step 8 */
 283                                 if (!BN_bin2bn(md, qsize, r0))
 284                                         goto err;
 285                                 if (!BN_lshift(r0,r0,(qsize << 3)*k)) goto err;
 286                                 if (!BN_add(W,W,r0)) goto err;
 287                                 }
 288
 289                         /* more of step 8 */
 290                         if (!BN_mask_bits(W,bits-1)) goto err;
 291                         if (!BN_copy(X,W)) goto err;
 292                         if (!BN_add(X,X,test)) goto err;
 293
 294                         /* step 9 */
 295                         if (!BN_lshift1(r0,q)) goto err;
 296                         if (!BN_mod(c,X,r0,ctx)) goto err;
 297                         if (!BN_sub(r0,c,BN_value_one())) goto err;
 298                         if (!BN_sub(p,X,r0)) goto err;
 299
 300                         /* step 10 */
 301                         if (BN_cmp(p,test) >= 0)
 302                                 {
 303                                 /* step 11 */
 304                                 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
 305                                                 ctx, 1, cb);
 306                                 if (r > 0)
 307                                                 goto end; /* found it */
 308                                 if (r != 0)
 309                                         goto err;
 310                                 }
 311
 312                         /* step 13 */
 313                         counter++;
 314                         /* "offset = offset + n + 1" */
 315
 316                         /* step 14 */
 317                         if (counter >= 4096) 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())) goto err;
 327         if (!BN_div(r0,NULL,test,q,ctx)) goto err;
 328
 329         if (!BN_set_word(test,h)) goto err;
 330         if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
 331
 332         for (;;)
 333                 {
 334                 /* g=test^r0%p */
 335                 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
 336                 if (!BN_is_one(g)) break;
 337                 if (!BN_add(test,test,BN_value_one())) goto err;
 338                 h++;
 339                 }
 340
 341         if(!BN_GENCB_call(cb, 3, 1))
 342                 goto err;
 343
 344         ok=1;
 345 err:
 346         if (ok)
 347                 {
 348                 if(ret->p) BN_free(ret->p);
 349                 if(ret->q) BN_free(ret->q);
 350                 if(ret->g) BN_free(ret->g);
 351                 ret->p=BN_dup(p);
 352                 ret->q=BN_dup(q);
 353                 ret->g=BN_dup(g);
 354                 if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
 355                         {
 356                         ok=0;
 357                         goto err;
 358                         }
 359                 if (counter_ret != NULL) *counter_ret=counter;
 360                 if (h_ret != NULL) *h_ret=h;
 361                 if (seed_out)
 362                         memcpy(seed_out, seed, qsize);
 363                 }
 364         if(ctx)
 365                 {
 366                 BN_CTX_end(ctx);
 367                 BN_CTX_free(ctx);
 368                 }
 369         if (mont != NULL) BN_MONT_CTX_free(mont);
 370         return ok;
 371         }
 372 #endif