dsa_gen.c revision 306196
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 "cryptlib.h" 82# include <openssl/evp.h> 83# include <openssl/bn.h> 84# include <openssl/rand.h> 85# include <openssl/sha.h> 86# include "dsa_locl.h" 87 88# ifdef OPENSSL_FIPS 89# include <openssl/fips.h> 90# endif 91 92int DSA_generate_parameters_ex(DSA *ret, int bits, 93 const unsigned char *seed_in, int seed_len, 94 int *counter_ret, unsigned long *h_ret, 95 BN_GENCB *cb) 96{ 97# ifdef OPENSSL_FIPS 98 if (FIPS_mode() && !(ret->meth->flags & DSA_FLAG_FIPS_METHOD) 99 && !(ret->flags & DSA_FLAG_NON_FIPS_ALLOW)) { 100 DSAerr(DSA_F_DSA_GENERATE_PARAMETERS_EX, DSA_R_NON_FIPS_DSA_METHOD); 101 return 0; 102 } 103# endif 104 if (ret->meth->dsa_paramgen) 105 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len, 106 counter_ret, h_ret, cb); 107# ifdef OPENSSL_FIPS 108 else if (FIPS_mode()) { 109 return FIPS_dsa_generate_parameters_ex(ret, bits, 110 seed_in, seed_len, 111 counter_ret, h_ret, cb); 112 } 113# endif 114 else { 115 const EVP_MD *evpmd = bits >= 2048 ? EVP_sha256() : EVP_sha1(); 116 size_t qbits = EVP_MD_size(evpmd) * 8; 117 118 return dsa_builtin_paramgen(ret, bits, qbits, evpmd, 119 seed_in, seed_len, NULL, counter_ret, 120 h_ret, cb); 121 } 122} 123 124int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits, 125 const EVP_MD *evpmd, const unsigned char *seed_in, 126 size_t seed_len, unsigned char *seed_out, 127 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb) 128{ 129 int ok = 0; 130 unsigned char seed[SHA256_DIGEST_LENGTH]; 131 unsigned char md[SHA256_DIGEST_LENGTH]; 132 unsigned char buf[SHA256_DIGEST_LENGTH], buf2[SHA256_DIGEST_LENGTH]; 133 BIGNUM *r0, *W, *X, *c, *test; 134 BIGNUM *g = NULL, *q = NULL, *p = NULL; 135 BN_MONT_CTX *mont = NULL; 136 int i, k, n = 0, m = 0, qsize = qbits >> 3; 137 int counter = 0; 138 int r = 0; 139 BN_CTX *ctx = NULL; 140 unsigned int h = 2; 141 142 if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH && 143 qsize != SHA256_DIGEST_LENGTH) 144 /* invalid q size */ 145 return 0; 146 147 if (evpmd == NULL) 148 /* use SHA1 as default */ 149 evpmd = EVP_sha1(); 150 151 if (bits < 512) 152 bits = 512; 153 154 bits = (bits + 63) / 64 * 64; 155 156 /* 157 * NB: seed_len == 0 is special case: copy generated seed to seed_in if 158 * it is not NULL. 159 */ 160 if (seed_len && (seed_len < (size_t)qsize)) 161 seed_in = NULL; /* seed buffer too small -- ignore */ 162 if (seed_len > (size_t)qsize) 163 seed_len = qsize; /* App. 2.2 of FIPS PUB 186 allows larger 164 * SEED, but our internal buffers are 165 * restricted to 160 bits */ 166 if (seed_in != NULL) 167 memcpy(seed, seed_in, seed_len); 168 169 if ((mont = BN_MONT_CTX_new()) == NULL) 170 goto err; 171 172 if ((ctx = BN_CTX_new()) == NULL) 173 goto err; 174 175 BN_CTX_start(ctx); 176 177 r0 = BN_CTX_get(ctx); 178 g = BN_CTX_get(ctx); 179 W = BN_CTX_get(ctx); 180 q = BN_CTX_get(ctx); 181 X = BN_CTX_get(ctx); 182 c = BN_CTX_get(ctx); 183 p = BN_CTX_get(ctx); 184 test = BN_CTX_get(ctx); 185 186 if (!BN_lshift(test, BN_value_one(), bits - 1)) 187 goto err; 188 189 for (;;) { 190 for (;;) { /* find q */ 191 int seed_is_random; 192 193 /* step 1 */ 194 if (!BN_GENCB_call(cb, 0, m++)) 195 goto err; 196 197 if (!seed_len || !seed_in) { 198 if (RAND_bytes(seed, qsize) <= 0) 199 goto err; 200 seed_is_random = 1; 201 } else { 202 seed_is_random = 0; 203 seed_len = 0; /* use random seed if 'seed_in' turns out to 204 * be bad */ 205 } 206 memcpy(buf, seed, qsize); 207 memcpy(buf2, seed, qsize); 208 /* precompute "SEED + 1" for step 7: */ 209 for (i = qsize - 1; i >= 0; i--) { 210 buf[i]++; 211 if (buf[i] != 0) 212 break; 213 } 214 215 /* step 2 */ 216 if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL)) 217 goto err; 218 if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL)) 219 goto err; 220 for (i = 0; i < qsize; i++) 221 md[i] ^= buf2[i]; 222 223 /* step 3 */ 224 md[0] |= 0x80; 225 md[qsize - 1] |= 0x01; 226 if (!BN_bin2bn(md, qsize, q)) 227 goto err; 228 229 /* step 4 */ 230 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx, 231 seed_is_random, cb); 232 if (r > 0) 233 break; 234 if (r != 0) 235 goto err; 236 237 /* do a callback call */ 238 /* step 5 */ 239 } 240 241 if (!BN_GENCB_call(cb, 2, 0)) 242 goto err; 243 if (!BN_GENCB_call(cb, 3, 0)) 244 goto err; 245 246 /* step 6 */ 247 counter = 0; 248 /* "offset = 2" */ 249 250 n = (bits - 1) / 160; 251 252 for (;;) { 253 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter)) 254 goto err; 255 256 /* step 7 */ 257 BN_zero(W); 258 /* now 'buf' contains "SEED + offset - 1" */ 259 for (k = 0; k <= n; k++) { 260 /* 261 * obtain "SEED + offset + k" by incrementing: 262 */ 263 for (i = qsize - 1; i >= 0; i--) { 264 buf[i]++; 265 if (buf[i] != 0) 266 break; 267 } 268 269 if (!EVP_Digest(buf, qsize, md, NULL, evpmd, NULL)) 270 goto err; 271 272 /* step 8 */ 273 if (!BN_bin2bn(md, qsize, r0)) 274 goto err; 275 if (!BN_lshift(r0, r0, (qsize << 3) * k)) 276 goto err; 277 if (!BN_add(W, W, r0)) 278 goto err; 279 } 280 281 /* more of step 8 */ 282 if (!BN_mask_bits(W, bits - 1)) 283 goto err; 284 if (!BN_copy(X, W)) 285 goto err; 286 if (!BN_add(X, X, test)) 287 goto err; 288 289 /* step 9 */ 290 if (!BN_lshift1(r0, q)) 291 goto err; 292 if (!BN_mod(c, X, r0, ctx)) 293 goto err; 294 if (!BN_sub(r0, c, BN_value_one())) 295 goto err; 296 if (!BN_sub(p, X, r0)) 297 goto err; 298 299 /* step 10 */ 300 if (BN_cmp(p, test) >= 0) { 301 /* step 11 */ 302 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb); 303 if (r > 0) 304 goto end; /* found it */ 305 if (r != 0) 306 goto err; 307 } 308 309 /* step 13 */ 310 counter++; 311 /* "offset = offset + n + 1" */ 312 313 /* step 14 */ 314 if (counter >= 4096) 315 break; 316 } 317 } 318 end: 319 if (!BN_GENCB_call(cb, 2, 1)) 320 goto err; 321 322 /* We now need to generate g */ 323 /* Set r0=(p-1)/q */ 324 if (!BN_sub(test, p, BN_value_one())) 325 goto err; 326 if (!BN_div(r0, NULL, test, q, ctx)) 327 goto err; 328 329 if (!BN_set_word(test, h)) 330 goto err; 331 if (!BN_MONT_CTX_set(mont, p, ctx)) 332 goto err; 333 334 for (;;) { 335 /* g=test^r0%p */ 336 if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont)) 337 goto err; 338 if (!BN_is_one(g)) 339 break; 340 if (!BN_add(test, test, BN_value_one())) 341 goto err; 342 h++; 343 } 344 345 if (!BN_GENCB_call(cb, 3, 1)) 346 goto err; 347 348 ok = 1; 349 err: 350 if (ok) { 351 if (ret->p) 352 BN_free(ret->p); 353 if (ret->q) 354 BN_free(ret->q); 355 if (ret->g) 356 BN_free(ret->g); 357 ret->p = BN_dup(p); 358 ret->q = BN_dup(q); 359 ret->g = BN_dup(g); 360 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) { 361 ok = 0; 362 goto err; 363 } 364 if (counter_ret != NULL) 365 *counter_ret = counter; 366 if (h_ret != NULL) 367 *h_ret = h; 368 if (seed_out) 369 memcpy(seed_out, seed, qsize); 370 } 371 if (ctx) { 372 BN_CTX_end(ctx); 373 BN_CTX_free(ctx); 374 } 375 if (mont != NULL) 376 BN_MONT_CTX_free(mont); 377 return ok; 378} 379#endif 380