dsa_gen.c revision 1.12
1/* $OpenBSD: dsa_gen.c,v 1.12 2014/06/12 15:49:28 deraadt Exp $ */ 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 84int DSA_generate_parameters_ex(DSA *ret, int bits, 85 const unsigned char *seed_in, int seed_len, 86 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb) 87 { 88 if(ret->meth->dsa_paramgen) 89 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len, 90 counter_ret, h_ret, cb); 91 else 92 { 93 const EVP_MD *evpmd; 94 size_t qbits = bits >= 2048 ? 256 : 160; 95 96 if (bits >= 2048) 97 { 98 qbits = 256; 99 evpmd = EVP_sha256(); 100 } 101 else 102 { 103 qbits = 160; 104 evpmd = EVP_sha1(); 105 } 106 107 return dsa_builtin_paramgen(ret, bits, qbits, evpmd, 108 seed_in, seed_len, NULL, counter_ret, h_ret, cb); 109 } 110 } 111 112int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits, 113 const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len, 114 unsigned char *seed_out, 115 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb) 116 { 117 int ok=0; 118 unsigned char seed[SHA256_DIGEST_LENGTH]; 119 unsigned char md[SHA256_DIGEST_LENGTH]; 120 unsigned char buf[SHA256_DIGEST_LENGTH],buf2[SHA256_DIGEST_LENGTH]; 121 BIGNUM *r0,*W,*X,*c,*test; 122 BIGNUM *g=NULL,*q=NULL,*p=NULL; 123 BN_MONT_CTX *mont=NULL; 124 int i, k, n=0, m=0, qsize = qbits >> 3; 125 int counter=0; 126 int r=0; 127 BN_CTX *ctx=NULL; 128 unsigned int h=2; 129 130 if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH && 131 qsize != SHA256_DIGEST_LENGTH) 132 /* invalid q size */ 133 return 0; 134 135 if (evpmd == NULL) 136 /* use SHA1 as default */ 137 evpmd = EVP_sha1(); 138 139 if (bits < 512) 140 bits = 512; 141 142 bits = (bits+63)/64*64; 143 144 /* NB: seed_len == 0 is special case: copy generated seed to 145 * seed_in if it is not NULL. 146 */ 147 if (seed_len && (seed_len < (size_t)qsize)) 148 seed_in = NULL; /* seed buffer too small -- ignore */ 149 if (seed_len > (size_t)qsize) 150 seed_len = qsize; /* App. 2.2 of FIPS PUB 186 allows larger SEED, 151 * but our internal buffers are restricted to 160 bits*/ 152 if (seed_in != NULL) 153 memcpy(seed, seed_in, seed_len); 154 155 if ((ctx=BN_CTX_new()) == NULL) 156 goto err; 157 158 if ((mont=BN_MONT_CTX_new()) == NULL) 159 goto err; 160 161 BN_CTX_start(ctx); 162 r0 = BN_CTX_get(ctx); 163 g = BN_CTX_get(ctx); 164 W = BN_CTX_get(ctx); 165 q = BN_CTX_get(ctx); 166 X = BN_CTX_get(ctx); 167 c = BN_CTX_get(ctx); 168 p = BN_CTX_get(ctx); 169 test = BN_CTX_get(ctx); 170 171 if (!BN_lshift(test,BN_value_one(),bits-1)) 172 goto err; 173 174 for (;;) 175 { 176 for (;;) /* find q */ 177 { 178 int seed_is_random; 179 180 /* step 1 */ 181 if(!BN_GENCB_call(cb, 0, m++)) 182 goto err; 183 184 if (!seed_len) 185 { 186 RAND_pseudo_bytes(seed, qsize); 187 seed_is_random = 1; 188 } 189 else 190 { 191 seed_is_random = 0; 192 seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/ 193 } 194 memcpy(buf , seed, qsize); 195 memcpy(buf2, seed, qsize); 196 /* precompute "SEED + 1" for step 7: */ 197 for (i = qsize-1; i >= 0; i--) 198 { 199 buf[i]++; 200 if (buf[i] != 0) 201 break; 202 } 203 204 /* step 2 */ 205 if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL)) 206 goto err; 207 if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL)) 208 goto err; 209 for (i = 0; i < qsize; i++) 210 md[i]^=buf2[i]; 211 212 /* step 3 */ 213 md[0] |= 0x80; 214 md[qsize-1] |= 0x01; 215 if (!BN_bin2bn(md, qsize, q)) 216 goto err; 217 218 /* step 4 */ 219 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx, 220 seed_is_random, cb); 221 if (r > 0) 222 break; 223 if (r != 0) 224 goto err; 225 226 /* do a callback call */ 227 /* step 5 */ 228 } 229 230 if(!BN_GENCB_call(cb, 2, 0)) goto err; 231 if(!BN_GENCB_call(cb, 3, 0)) goto err; 232 233 /* step 6 */ 234 counter=0; 235 /* "offset = 2" */ 236 237 n=(bits-1)/160; 238 239 for (;;) 240 { 241 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter)) 242 goto err; 243 244 /* step 7 */ 245 BN_zero(W); 246 /* now 'buf' contains "SEED + offset - 1" */ 247 for (k=0; k<=n; k++) 248 { 249 /* obtain "SEED + offset + k" by incrementing: */ 250 for (i = qsize-1; i >= 0; i--) 251 { 252 buf[i]++; 253 if (buf[i] != 0) 254 break; 255 } 256 257 if (!EVP_Digest(buf, qsize, md ,NULL, evpmd, 258 NULL)) 259 goto err; 260 261 /* step 8 */ 262 if (!BN_bin2bn(md, qsize, r0)) 263 goto err; 264 if (!BN_lshift(r0,r0,(qsize << 3)*k)) goto err; 265 if (!BN_add(W,W,r0)) goto err; 266 } 267 268 /* more of step 8 */ 269 if (!BN_mask_bits(W,bits-1)) goto err; 270 if (!BN_copy(X,W)) goto err; 271 if (!BN_add(X,X,test)) goto err; 272 273 /* step 9 */ 274 if (!BN_lshift1(r0,q)) goto err; 275 if (!BN_mod(c,X,r0,ctx)) goto err; 276 if (!BN_sub(r0,c,BN_value_one())) goto err; 277 if (!BN_sub(p,X,r0)) goto err; 278 279 /* step 10 */ 280 if (BN_cmp(p,test) >= 0) 281 { 282 /* step 11 */ 283 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, 284 ctx, 1, cb); 285 if (r > 0) 286 goto end; /* found it */ 287 if (r != 0) 288 goto err; 289 } 290 291 /* step 13 */ 292 counter++; 293 /* "offset = offset + n + 1" */ 294 295 /* step 14 */ 296 if (counter >= 4096) break; 297 } 298 } 299end: 300 if(!BN_GENCB_call(cb, 2, 1)) 301 goto err; 302 303 /* We now need to generate g */ 304 /* Set r0=(p-1)/q */ 305 if (!BN_sub(test,p,BN_value_one())) goto err; 306 if (!BN_div(r0,NULL,test,q,ctx)) goto err; 307 308 if (!BN_set_word(test,h)) goto err; 309 if (!BN_MONT_CTX_set(mont,p,ctx)) goto err; 310 311 for (;;) 312 { 313 /* g=test^r0%p */ 314 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err; 315 if (!BN_is_one(g)) break; 316 if (!BN_add(test,test,BN_value_one())) goto err; 317 h++; 318 } 319 320 if(!BN_GENCB_call(cb, 3, 1)) 321 goto err; 322 323 ok=1; 324err: 325 if (ok) 326 { 327 if(ret->p) BN_free(ret->p); 328 if(ret->q) BN_free(ret->q); 329 if(ret->g) BN_free(ret->g); 330 ret->p=BN_dup(p); 331 ret->q=BN_dup(q); 332 ret->g=BN_dup(g); 333 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) 334 { 335 ok=0; 336 goto err; 337 } 338 if (counter_ret != NULL) *counter_ret=counter; 339 if (h_ret != NULL) *h_ret=h; 340 if (seed_out) 341 memcpy(seed_out, seed, qsize); 342 } 343 if(ctx) 344 { 345 BN_CTX_end(ctx); 346 BN_CTX_free(ctx); 347 } 348 if (mont != NULL) BN_MONT_CTX_free(mont); 349 return ok; 350 } 351#endif 352