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 #ifndef OPENSSL_NO_SHA
  73
  74 #include <stdio.h>
  75 #include <time.h>
  76 #include "cryptlib.h"
  77 #include <openssl/evp.h>
  78 #include <openssl/bn.h>
  79 #include <openssl/dsa.h>
  80 #include <openssl/rand.h>
  81 #include <openssl/sha.h>
  82
  83 static int dsa_builtin_paramgen(DSA *ret, int bits,
  84                 unsigned char *seed_in, int seed_len,
  85                 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb);
  86
  87 int DSA_generate_parameters_ex(DSA *ret, int bits,
  88                 unsigned char *seed_in, int seed_len,
  89                 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
  90         {
  91         if(ret->meth->dsa_paramgen)
  92                 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
  93                                 counter_ret, h_ret, cb);
  94         return dsa_builtin_paramgen(ret, bits, seed_in, seed_len,
  95                         counter_ret, h_ret, cb);
  96         }
  97
  98 static int dsa_builtin_paramgen(DSA *ret, int bits,
  99                 unsigned char *seed_in, int seed_len,
 100                 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
 101         {
 102         int ok=0;
 103         unsigned char seed[SHA_DIGEST_LENGTH];
 104         unsigned char md[SHA_DIGEST_LENGTH];
 105         unsigned char buf[SHA_DIGEST_LENGTH],buf2[SHA_DIGEST_LENGTH];
 106         BIGNUM *r0,*W,*X,*c,*test;
 107         BIGNUM *g=NULL,*q=NULL,*p=NULL;
 108         BN_MONT_CTX *mont=NULL;
 109         int k,n=0,i,b,m=0;
 110         int counter=0;
 111         int r=0;
 112         BN_CTX *ctx=NULL,*ctx2=NULL,*ctx3=NULL;
 113         unsigned int h=2;
 114
 115         if (bits < 512) bits=512;
 116         bits=(bits+63)/64*64;
 117
 118         if (seed_len < 20)
 119                 seed_in = NULL; /* seed buffer too small -- ignore */
 120         if (seed_len > 20)
 121                 seed_len = 20; /* App. 2.2 of FIPS PUB 186 allows larger SEED,
 122                                 * but our internal buffers are restricted to 160 bits*/
 123         if ((seed_in != NULL) && (seed_len == 20))
 124                 memcpy(seed,seed_in,seed_len);
 125
 126         if ((ctx=BN_CTX_new()) == NULL) goto err;
 127         if ((ctx2=BN_CTX_new()) == NULL) goto err;
 128         if ((ctx3=BN_CTX_new()) == NULL) goto err;
 129
 130         if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
 131
 132         BN_CTX_start(ctx2);
 133         r0 = BN_CTX_get(ctx2);
 134         g = BN_CTX_get(ctx2);
 135         W = BN_CTX_get(ctx2);
 136         q = BN_CTX_get(ctx2);
 137         X = BN_CTX_get(ctx2);
 138         c = BN_CTX_get(ctx2);
 139         p = BN_CTX_get(ctx2);
 140         test = BN_CTX_get(ctx2);
 141
 142         BN_lshift(test,BN_value_one(),bits-1);
 143
 144         for (;;)
 145                 {
 146                 for (;;) /* find q */
 147                         {
 148                         int seed_is_random;
 149
 150                         /* step 1 */
 151                         if(!BN_GENCB_call(cb, 0, m++))
 152                                 goto err;
 153
 154                         if (!seed_len)
 155                                 {
 156                                 RAND_pseudo_bytes(seed,SHA_DIGEST_LENGTH);
 157                                 seed_is_random = 1;
 158                                 }
 159                         else
 160                                 {
 161                                 seed_is_random = 0;
 162                                 seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/
 163                                 }
 164                         memcpy(buf,seed,SHA_DIGEST_LENGTH);
 165                         memcpy(buf2,seed,SHA_DIGEST_LENGTH);
 166                         /* precompute "SEED + 1" for step 7: */
 167                         for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
 168                                 {
 169                                 buf[i]++;
 170                                 if (buf[i] != 0) break;
 171                                 }
 172
 173                         /* step 2 */
 174                         EVP_Digest(seed,SHA_DIGEST_LENGTH,md,NULL,HASH, NULL);
 175                         EVP_Digest(buf,SHA_DIGEST_LENGTH,buf2,NULL,HASH, NULL);
 176                         for (i=0; i<SHA_DIGEST_LENGTH; i++)
 177                                 md[i]^=buf2[i];
 178
 179                         /* step 3 */
 180                         md[0]|=0x80;
 181                         md[SHA_DIGEST_LENGTH-1]|=0x01;
 182                         if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,q)) goto err;
 183
 184                         /* step 4 */
 185                         r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx3,
 186                                         seed_is_random, cb);
 187                         if (r > 0)
 188                                 break;
 189                         if (r != 0)
 190                                 goto err;
 191
 192                         /* do a callback call */
 193                         /* step 5 */
 194                         }
 195
 196                 if(!BN_GENCB_call(cb, 2, 0)) goto err;
 197                 if(!BN_GENCB_call(cb, 3, 0)) goto err;
 198
 199                 /* step 6 */
 200                 counter=0;
 201                 /* "offset = 2" */
 202
 203                 n=(bits-1)/160;
 204                 b=(bits-1)-n*160;
 205
 206                 for (;;)
 207                         {
 208                         if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
 209                                 goto err;
 210
 211                         /* step 7 */
 212                         BN_zero(W);
 213                         /* now 'buf' contains "SEED + offset - 1" */
 214                         for (k=0; k<=n; k++)
 215                                 {
 216                                 /* obtain "SEED + offset + k" by incrementing: */
 217                                 for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
 218                                         {
 219                                         buf[i]++;
 220                                         if (buf[i] != 0) break;
 221                                         }
 222
 223                                 EVP_Digest(buf,SHA_DIGEST_LENGTH,md,NULL,HASH, NULL);
 224
 225                                 /* step 8 */
 226                                 if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,r0))
 227                                         goto err;
 228                                 BN_lshift(r0,r0,160*k);
 229                                 BN_add(W,W,r0);
 230                                 }
 231
 232                         /* more of step 8 */
 233                         BN_mask_bits(W,bits-1);
 234                         BN_copy(X,W); /* this should be ok */
 235                         BN_add(X,X,test); /* this should be ok */
 236
 237                         /* step 9 */
 238                         BN_lshift1(r0,q);
 239                         BN_mod(c,X,r0,ctx);
 240                         BN_sub(r0,c,BN_value_one());
 241                         BN_sub(p,X,r0);
 242
 243                         /* step 10 */
 244                         if (BN_cmp(p,test) >= 0)
 245                                 {
 246                                 /* step 11 */
 247                                 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
 248                                                 ctx3, 1, cb);
 249                                 if (r > 0)
 250                                                 goto end; /* found it */
 251                                 if (r != 0)
 252                                         goto err;
 253                                 }
 254
 255                         /* step 13 */
 256                         counter++;
 257                         /* "offset = offset + n + 1" */
 258
 259                         /* step 14 */
 260                         if (counter >= 4096) break;
 261                         }
 262                 }
 263 end:
 264         if(!BN_GENCB_call(cb, 2, 1))
 265                 goto err;
 266
 267         /* We now need to generate g */
 268         /* Set r0=(p-1)/q */
 269         BN_sub(test,p,BN_value_one());
 270         BN_div(r0,NULL,test,q,ctx);
 271
 272         BN_set_word(test,h);
 273         BN_MONT_CTX_set(mont,p,ctx);
 274
 275         for (;;)
 276                 {
 277                 /* g=test^r0%p */
 278                 BN_mod_exp_mont(g,test,r0,p,ctx,mont);
 279                 if (!BN_is_one(g)) break;
 280                 BN_add(test,test,BN_value_one());
 281                 h++;
 282                 }
 283
 284         if(!BN_GENCB_call(cb, 3, 1))
 285                 goto err;
 286
 287         ok=1;
 288 err:
 289         if (ok)
 290                 {
 291                 if(ret->p) BN_free(ret->p);
 292                 if(ret->q) BN_free(ret->q);
 293                 if(ret->g) BN_free(ret->g);
 294                 ret->p=BN_dup(p);
 295                 ret->q=BN_dup(q);
 296                 ret->g=BN_dup(g);
 297                 if ((m > 1) && (seed_in != NULL)) memcpy(seed_in,seed,20);
 298                 if (counter_ret != NULL) *counter_ret=counter;
 299                 if (h_ret != NULL) *h_ret=h;
 300                 }
 301         if (ctx != NULL) BN_CTX_free(ctx);
 302         if (ctx2 != NULL)
 303                 {
 304                 BN_CTX_end(ctx2);
 305                 BN_CTX_free(ctx2);
 306                 }
 307         if (ctx3 != NULL) BN_CTX_free(ctx3);
 308         if (mont != NULL) BN_MONT_CTX_free(mont);
 309         return ok;
 310         }
 311 #endif