dsa_gen.c revision 296465
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 91static 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 96int 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 108static 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 353