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#include <stdio.h> 77#include "cryptlib.h" 78#include <openssl/evp.h> 79#include <openssl/bn.h> 80#include <openssl/rand.h> 81#include <openssl/sha.h> 82#include "dsa_locl.h" 83 84#ifdef OPENSSL_FIPS 85#include <openssl/fips.h> 86#endif 87 88int DSA_generate_parameters_ex(DSA *ret, int bits, 89 const unsigned char *seed_in, int seed_len, 90 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb) 91 { 92#ifdef OPENSSL_FIPS 93 if (FIPS_mode() && !(ret->meth->flags & DSA_FLAG_FIPS_METHOD) 94 && !(ret->flags & DSA_FLAG_NON_FIPS_ALLOW)) 95 { 96 DSAerr(DSA_F_DSA_GENERATE_PARAMETERS_EX, DSA_R_NON_FIPS_DSA_METHOD); 97 return 0; 98 } 99#endif 100 if(ret->meth->dsa_paramgen) 101 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len, 102 counter_ret, h_ret, cb); 103#ifdef OPENSSL_FIPS 104 else if (FIPS_mode()) 105 { 106 return FIPS_dsa_generate_parameters_ex(ret, bits, 107 seed_in, seed_len, 108 counter_ret, h_ret, cb); 109 } 110#endif 111 else 112 { 113 const EVP_MD *evpmd; 114 size_t qbits = bits >= 2048 ? 256 : 160; 115 116 if (bits >= 2048) 117 { 118 qbits = 256; 119 evpmd = EVP_sha256(); 120 } 121 else 122 { 123 qbits = 160; 124 evpmd = EVP_sha1(); 125 } 126 127 return dsa_builtin_paramgen(ret, bits, qbits, evpmd, 128 seed_in, seed_len, NULL, counter_ret, h_ret, cb); 129 } 130 } 131 132int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits, 133 const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len, 134 unsigned char *seed_out, 135 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb) 136 { 137 int ok=0; 138 unsigned char seed[SHA256_DIGEST_LENGTH]; 139 unsigned char md[SHA256_DIGEST_LENGTH]; 140 unsigned char buf[SHA256_DIGEST_LENGTH],buf2[SHA256_DIGEST_LENGTH]; 141 BIGNUM *r0,*W,*X,*c,*test; 142 BIGNUM *g=NULL,*q=NULL,*p=NULL; 143 BN_MONT_CTX *mont=NULL; 144 int i, k, n=0, m=0, qsize = qbits >> 3; 145 int counter=0; 146 int r=0; 147 BN_CTX *ctx=NULL; 148 unsigned int h=2; 149 150 if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH && 151 qsize != SHA256_DIGEST_LENGTH) 152 /* invalid q size */ 153 return 0; 154 155 if (evpmd == NULL) 156 /* use SHA1 as default */ 157 evpmd = EVP_sha1(); 158 159 if (bits < 512) 160 bits = 512; 161 162 bits = (bits+63)/64*64; 163 164 /* NB: seed_len == 0 is special case: copy generated seed to 165 * seed_in if it is not NULL. 166 */ 167 if (seed_len && (seed_len < (size_t)qsize)) 168 seed_in = NULL; /* seed buffer too small -- ignore */ 169 if (seed_len > (size_t)qsize) 170 seed_len = qsize; /* App. 2.2 of FIPS PUB 186 allows larger SEED, 171 * but our internal buffers are restricted to 160 bits*/ 172 if (seed_in != NULL) 173 memcpy(seed, seed_in, seed_len); 174 175 if ((ctx=BN_CTX_new()) == NULL) 176 goto err; 177 178 if ((mont=BN_MONT_CTX_new()) == NULL) 179 goto err; 180 181 BN_CTX_start(ctx); 182 r0 = BN_CTX_get(ctx); 183 g = BN_CTX_get(ctx); 184 W = BN_CTX_get(ctx); 185 q = BN_CTX_get(ctx); 186 X = BN_CTX_get(ctx); 187 c = BN_CTX_get(ctx); 188 p = BN_CTX_get(ctx); 189 test = BN_CTX_get(ctx); 190 191 if (!BN_lshift(test,BN_value_one(),bits-1)) 192 goto err; 193 194 for (;;) 195 { 196 for (;;) /* find q */ 197 { 198 int seed_is_random; 199 200 /* step 1 */ 201 if(!BN_GENCB_call(cb, 0, m++)) 202 goto err; 203 204 if (!seed_len) 205 { 206 RAND_pseudo_bytes(seed, qsize); 207 seed_is_random = 1; 208 } 209 else 210 { 211 seed_is_random = 0; 212 seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/ 213 } 214 memcpy(buf , seed, qsize); 215 memcpy(buf2, seed, qsize); 216 /* precompute "SEED + 1" for step 7: */ 217 for (i = qsize-1; i >= 0; i--) 218 { 219 buf[i]++; 220 if (buf[i] != 0) 221 break; 222 } 223 224 /* step 2 */ 225 if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL)) 226 goto err; 227 if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL)) 228 goto err; 229 for (i = 0; i < qsize; i++) 230 md[i]^=buf2[i]; 231 232 /* step 3 */ 233 md[0] |= 0x80; 234 md[qsize-1] |= 0x01; 235 if (!BN_bin2bn(md, qsize, q)) 236 goto err; 237 238 /* step 4 */ 239 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx, 240 seed_is_random, cb); 241 if (r > 0) 242 break; 243 if (r != 0) 244 goto err; 245 246 /* do a callback call */ 247 /* step 5 */ 248 } 249 250 if(!BN_GENCB_call(cb, 2, 0)) goto err; 251 if(!BN_GENCB_call(cb, 3, 0)) goto err; 252 253 /* step 6 */ 254 counter=0; 255 /* "offset = 2" */ 256 257 n=(bits-1)/160; 258 259 for (;;) 260 { 261 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter)) 262 goto err; 263 264 /* step 7 */ 265 BN_zero(W); 266 /* now 'buf' contains "SEED + offset - 1" */ 267 for (k=0; k<=n; k++) 268 { 269 /* obtain "SEED + offset + k" by incrementing: */ 270 for (i = qsize-1; i >= 0; i--) 271 { 272 buf[i]++; 273 if (buf[i] != 0) 274 break; 275 } 276 277 if (!EVP_Digest(buf, qsize, md ,NULL, evpmd, 278 NULL)) 279 goto err; 280 281 /* step 8 */ 282 if (!BN_bin2bn(md, qsize, r0)) 283 goto err; 284 if (!BN_lshift(r0,r0,(qsize << 3)*k)) goto err; 285 if (!BN_add(W,W,r0)) goto err; 286 } 287 288 /* more of step 8 */ 289 if (!BN_mask_bits(W,bits-1)) goto err; 290 if (!BN_copy(X,W)) goto err; 291 if (!BN_add(X,X,test)) goto err; 292 293 /* step 9 */ 294 if (!BN_lshift1(r0,q)) goto err; 295 if (!BN_mod(c,X,r0,ctx)) goto err; 296 if (!BN_sub(r0,c,BN_value_one())) goto err; 297 if (!BN_sub(p,X,r0)) goto err; 298 299 /* step 10 */ 300 if (BN_cmp(p,test) >= 0) 301 { 302 /* step 11 */ 303 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, 304 ctx, 1, cb); 305 if (r > 0) 306 goto end; /* found it */ 307 if (r != 0) 308 goto err; 309 } 310 311 /* step 13 */ 312 counter++; 313 /* "offset = offset + n + 1" */ 314 315 /* step 14 */ 316 if (counter >= 4096) break; 317 } 318 } 319end: 320 if(!BN_GENCB_call(cb, 2, 1)) 321 goto err; 322 323 /* We now need to generate g */ 324 /* Set r0=(p-1)/q */ 325 if (!BN_sub(test,p,BN_value_one())) goto err; 326 if (!BN_div(r0,NULL,test,q,ctx)) goto err; 327 328 if (!BN_set_word(test,h)) goto err; 329 if (!BN_MONT_CTX_set(mont,p,ctx)) goto err; 330 331 for (;;) 332 { 333 /* g=test^r0%p */ 334 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err; 335 if (!BN_is_one(g)) break; 336 if (!BN_add(test,test,BN_value_one())) goto err; 337 h++; 338 } 339 340 if(!BN_GENCB_call(cb, 3, 1)) 341 goto err; 342 343 ok=1; 344err: 345 if (ok) 346 { 347 if(ret->p) BN_free(ret->p); 348 if(ret->q) BN_free(ret->q); 349 if(ret->g) BN_free(ret->g); 350 ret->p=BN_dup(p); 351 ret->q=BN_dup(q); 352 ret->g=BN_dup(g); 353 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) 354 { 355 ok=0; 356 goto err; 357 } 358 if (counter_ret != NULL) *counter_ret=counter; 359 if (h_ret != NULL) *h_ret=h; 360 if (seed_out) 361 memcpy(seed_out, seed, qsize); 362 } 363 if(ctx) 364 { 365 BN_CTX_end(ctx); 366 BN_CTX_free(ctx); 367 } 368 if (mont != NULL) BN_MONT_CTX_free(mont); 369 return ok; 370 } 371#endif 372