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 /*
  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 <time.h>
  82 # include "cryptlib.h"
  83 # include <openssl/evp.h>
  84 # include <openssl/bn.h>
  85 # include <openssl/dsa.h>
  86 # include <openssl/rand.h>
  87 # include <openssl/sha.h>
  88
  89 # ifndef OPENSSL_FIPS
  90
  91 static int dsa_builtin_paramgen(DSA *ret, int bits,
  92                                 unsigned char *seed_in, int seed_len,
  93                                 int *counter_ret, unsigned long *h_ret,
  94                                 BN_GENCB *cb);
  95
  96 int DSA_generate_parameters_ex(DSA *ret, int bits,
  97                                unsigned char *seed_in, int seed_len,
  98                                int *counter_ret, unsigned long *h_ret,
  99                                BN_GENCB *cb)
 100 {
 101     if (ret->meth->dsa_paramgen)
 102         return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
 103                                        counter_ret, h_ret, cb);
 104     return dsa_builtin_paramgen(ret, bits, seed_in, seed_len,
 105                                 counter_ret, h_ret, cb);
 106 }
 107
 108 static int dsa_builtin_paramgen(DSA *ret, int bits,
 109                                 unsigned char *seed_in, int seed_len,
 110                                 int *counter_ret, unsigned long *h_ret,
 111                                 BN_GENCB *cb)
 112 {
 113     int ok = 0;
 114     unsigned char seed[SHA_DIGEST_LENGTH];
 115     unsigned char md[SHA_DIGEST_LENGTH];
 116     unsigned char buf[SHA_DIGEST_LENGTH], buf2[SHA_DIGEST_LENGTH];
 117     BIGNUM *r0, *W, *X, *c, *test;
 118     BIGNUM *g = NULL, *q = NULL, *p = NULL;
 119     BN_MONT_CTX *mont = NULL;
 120     int k, n = 0, i, m = 0;
 121     int counter = 0;
 122     int r = 0;
 123     BN_CTX *ctx = NULL;
 124     unsigned int h = 2;
 125
 126     if (bits < 512)
 127         bits = 512;
 128     bits = (bits + 63) / 64 * 64;
 129
 130     /*
 131      * NB: seed_len == 0 is special case: copy generated seed to seed_in if
 132      * it is not NULL.
 133      */
 134     if (seed_len && (seed_len < 20))
 135         seed_in = NULL;         /* seed buffer too small -- ignore */
 136     if (seed_len > 20)
 137         seed_len = 20;          /* App. 2.2 of FIPS PUB 186 allows larger
 138                                  * SEED, but our internal buffers are
 139                                  * restricted to 160 bits */
 140     if ((seed_in != NULL) && (seed_len == 20)) {
 141         memcpy(seed, seed_in, seed_len);
 142         /* set seed_in to NULL to avoid it being copied back */
 143         seed_in = NULL;
 144     }
 145
 146     if ((ctx = BN_CTX_new()) == NULL)
 147         goto err;
 148
 149     if ((mont = BN_MONT_CTX_new()) == NULL)
 150         goto err;
 151
 152     BN_CTX_start(ctx);
 153     r0 = BN_CTX_get(ctx);
 154     g = BN_CTX_get(ctx);
 155     W = BN_CTX_get(ctx);
 156     q = BN_CTX_get(ctx);
 157     X = BN_CTX_get(ctx);
 158     c = BN_CTX_get(ctx);
 159     p = BN_CTX_get(ctx);
 160     test = BN_CTX_get(ctx);
 161
 162     if (!BN_lshift(test, BN_value_one(), bits - 1))
 163         goto err;
 164
 165     for (;;) {
 166         for (;;) {              /* find q */
 167             int seed_is_random;
 168
 169             /* step 1 */
 170             if (!BN_GENCB_call(cb, 0, m++))
 171                 goto err;
 172
 173             if (!seed_len) {
 174                 RAND_pseudo_bytes(seed, SHA_DIGEST_LENGTH);
 175                 seed_is_random = 1;
 176             } else {
 177                 seed_is_random = 0;
 178                 seed_len = 0;   /* use random seed if 'seed_in' turns out to
 179                                  * be bad */
 180             }
 181             memcpy(buf, seed, SHA_DIGEST_LENGTH);
 182             memcpy(buf2, seed, SHA_DIGEST_LENGTH);
 183             /* precompute "SEED + 1" for step 7: */
 184             for (i = SHA_DIGEST_LENGTH - 1; i >= 0; i--) {
 185                 buf[i]++;
 186                 if (buf[i] != 0)
 187                     break;
 188             }
 189
 190             /* step 2 */
 191             EVP_Digest(seed, SHA_DIGEST_LENGTH, md, NULL, HASH, NULL);
 192             EVP_Digest(buf, SHA_DIGEST_LENGTH, buf2, NULL, HASH, NULL);
 193             for (i = 0; i < SHA_DIGEST_LENGTH; i++)
 194                 md[i] ^= buf2[i];
 195
 196             /* step 3 */
 197             md[0] |= 0x80;
 198             md[SHA_DIGEST_LENGTH - 1] |= 0x01;
 199             if (!BN_bin2bn(md, SHA_DIGEST_LENGTH, q))
 200                 goto err;
 201
 202             /* step 4 */
 203             r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
 204                                         seed_is_random, cb);
 205             if (r > 0)
 206                 break;
 207             if (r != 0)
 208                 goto err;
 209
 210             /* do a callback call */
 211             /* step 5 */
 212         }
 213
 214         if (!BN_GENCB_call(cb, 2, 0))
 215             goto err;
 216         if (!BN_GENCB_call(cb, 3, 0))
 217             goto err;
 218
 219         /* step 6 */
 220         counter = 0;
 221         /* "offset = 2" */
 222
 223         n = (bits - 1) / 160;
 224
 225         for (;;) {
 226             if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
 227                 goto err;
 228
 229             /* step 7 */
 230             BN_zero(W);
 231             /* now 'buf' contains "SEED + offset - 1" */
 232             for (k = 0; k <= n; k++) {
 233                 /*
 234                  * obtain "SEED + offset + k" by incrementing:
 235                  */
 236                 for (i = SHA_DIGEST_LENGTH - 1; i >= 0; i--) {
 237                     buf[i]++;
 238                     if (buf[i] != 0)
 239                         break;
 240                 }
 241
 242                 EVP_Digest(buf, SHA_DIGEST_LENGTH, md, NULL, HASH, NULL);
 243
 244                 /* step 8 */
 245                 if (!BN_bin2bn(md, SHA_DIGEST_LENGTH, r0))
 246                     goto err;
 247                 if (!BN_lshift(r0, r0, 160 * k))
 248                     goto err;
 249                 if (!BN_add(W, W, r0))
 250                     goto err;
 251             }
 252
 253             /* more of step 8 */
 254             if (!BN_mask_bits(W, bits - 1))
 255                 goto err;
 256             if (!BN_copy(X, W))
 257                 goto err;
 258             if (!BN_add(X, X, test))
 259                 goto err;
 260
 261             /* step 9 */
 262             if (!BN_lshift1(r0, q))
 263                 goto err;
 264             if (!BN_mod(c, X, r0, ctx))
 265                 goto err;
 266             if (!BN_sub(r0, c, BN_value_one()))
 267                 goto err;
 268             if (!BN_sub(p, X, r0))
 269                 goto err;
 270
 271             /* step 10 */
 272             if (BN_cmp(p, test) >= 0) {
 273                 /* step 11 */
 274                 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb);
 275                 if (r > 0)
 276                     goto end;   /* found it */
 277                 if (r != 0)
 278                     goto err;
 279             }
 280
 281             /* step 13 */
 282             counter++;
 283             /* "offset = offset + n + 1" */
 284
 285             /* step 14 */
 286             if (counter >= 4096)
 287                 break;
 288         }
 289     }
 290  end:
 291     if (!BN_GENCB_call(cb, 2, 1))
 292         goto err;
 293
 294     /* We now need to generate g */
 295     /* Set r0=(p-1)/q */
 296     if (!BN_sub(test, p, BN_value_one()))
 297         goto err;
 298     if (!BN_div(r0, NULL, test, q, ctx))
 299         goto err;
 300
 301     if (!BN_set_word(test, h))
 302         goto err;
 303     if (!BN_MONT_CTX_set(mont, p, ctx))
 304         goto err;
 305
 306     for (;;) {
 307         /* g=test^r0%p */
 308         if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont))
 309             goto err;
 310         if (!BN_is_one(g))
 311             break;
 312         if (!BN_add(test, test, BN_value_one()))
 313             goto err;
 314         h++;
 315     }
 316
 317     if (!BN_GENCB_call(cb, 3, 1))
 318         goto err;
 319
 320     ok = 1;
 321  err:
 322     if (ok) {
 323         if (ret->p)
 324             BN_free(ret->p);
 325         if (ret->q)
 326             BN_free(ret->q);
 327         if (ret->g)
 328             BN_free(ret->g);
 329         ret->p = BN_dup(p);
 330         ret->q = BN_dup(q);
 331         ret->g = BN_dup(g);
 332         if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
 333             ok = 0;
 334             goto err;
 335         }
 336         if (seed_in != NULL)
 337             memcpy(seed_in, seed, 20);
 338         if (counter_ret != NULL)
 339             *counter_ret = counter;
 340         if (h_ret != NULL)
 341             *h_ret = h;
 342     }
 343     if (ctx) {
 344         BN_CTX_end(ctx);
 345         BN_CTX_free(ctx);
 346     }
 347     if (mont != NULL)
 348         BN_MONT_CTX_free(mont);
 349     return ok;
 350 }
 351 # endif
 352 #endif