dsa_gen.c revision 1.7
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 <time.h> 78#include "cryptlib.h" 79#include <openssl/evp.h> 80#include <openssl/bn.h> 81#include <openssl/dsa.h> 82#include <openssl/rand.h> 83#include <openssl/sha.h> 84 85#ifndef OPENSSL_FIPS 86 87static int dsa_builtin_paramgen(DSA *ret, int bits, 88 unsigned char *seed_in, int seed_len, 89 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb); 90 91int DSA_generate_parameters_ex(DSA *ret, int bits, 92 unsigned char *seed_in, int seed_len, 93 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb) 94 { 95 if(ret->meth->dsa_paramgen) 96 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len, 97 counter_ret, h_ret, cb); 98 return dsa_builtin_paramgen(ret, bits, seed_in, seed_len, 99 counter_ret, h_ret, cb); 100 } 101 102static int dsa_builtin_paramgen(DSA *ret, int bits, 103 unsigned char *seed_in, int seed_len, 104 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb) 105 { 106 int ok=0; 107 unsigned char seed[SHA_DIGEST_LENGTH]; 108 unsigned char md[SHA_DIGEST_LENGTH]; 109 unsigned char buf[SHA_DIGEST_LENGTH],buf2[SHA_DIGEST_LENGTH]; 110 BIGNUM *r0,*W,*X,*c,*test; 111 BIGNUM *g=NULL,*q=NULL,*p=NULL; 112 BN_MONT_CTX *mont=NULL; 113 int k,n=0,i,b,m=0; 114 int counter=0; 115 int r=0; 116 BN_CTX *ctx=NULL; 117 unsigned int h=2; 118 119 if (bits < 512) bits=512; 120 bits=(bits+63)/64*64; 121 122 /* NB: seed_len == 0 is special case: copy generated seed to 123 * seed_in if it is not NULL. 124 */ 125 if (seed_len && (seed_len < 20)) 126 seed_in = NULL; /* seed buffer too small -- ignore */ 127 if (seed_len > 20) 128 seed_len = 20; /* App. 2.2 of FIPS PUB 186 allows larger SEED, 129 * but our internal buffers are restricted to 160 bits*/ 130 if ((seed_in != NULL) && (seed_len == 20)) 131 { 132 memcpy(seed,seed_in,seed_len); 133 /* set seed_in to NULL to avoid it being copied back */ 134 seed_in = NULL; 135 } 136 137 if ((ctx=BN_CTX_new()) == NULL) goto err; 138 139 if ((mont=BN_MONT_CTX_new()) == NULL) goto err; 140 141 BN_CTX_start(ctx); 142 r0 = BN_CTX_get(ctx); 143 g = BN_CTX_get(ctx); 144 W = BN_CTX_get(ctx); 145 q = BN_CTX_get(ctx); 146 X = BN_CTX_get(ctx); 147 c = BN_CTX_get(ctx); 148 p = BN_CTX_get(ctx); 149 test = BN_CTX_get(ctx); 150 151 if (!BN_lshift(test,BN_value_one(),bits-1)) 152 goto err; 153 154 for (;;) 155 { 156 for (;;) /* find q */ 157 { 158 int seed_is_random; 159 160 /* step 1 */ 161 if(!BN_GENCB_call(cb, 0, m++)) 162 goto err; 163 164 if (!seed_len) 165 { 166 RAND_pseudo_bytes(seed,SHA_DIGEST_LENGTH); 167 seed_is_random = 1; 168 } 169 else 170 { 171 seed_is_random = 0; 172 seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/ 173 } 174 memcpy(buf,seed,SHA_DIGEST_LENGTH); 175 memcpy(buf2,seed,SHA_DIGEST_LENGTH); 176 /* precompute "SEED + 1" for step 7: */ 177 for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--) 178 { 179 buf[i]++; 180 if (buf[i] != 0) break; 181 } 182 183 /* step 2 */ 184 EVP_Digest(seed,SHA_DIGEST_LENGTH,md,NULL,HASH, NULL); 185 EVP_Digest(buf,SHA_DIGEST_LENGTH,buf2,NULL,HASH, NULL); 186 for (i=0; i<SHA_DIGEST_LENGTH; i++) 187 md[i]^=buf2[i]; 188 189 /* step 3 */ 190 md[0]|=0x80; 191 md[SHA_DIGEST_LENGTH-1]|=0x01; 192 if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,q)) goto err; 193 194 /* step 4 */ 195 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx, 196 seed_is_random, cb); 197 if (r > 0) 198 break; 199 if (r != 0) 200 goto err; 201 202 /* do a callback call */ 203 /* step 5 */ 204 } 205 206 if(!BN_GENCB_call(cb, 2, 0)) goto err; 207 if(!BN_GENCB_call(cb, 3, 0)) goto err; 208 209 /* step 6 */ 210 counter=0; 211 /* "offset = 2" */ 212 213 n=(bits-1)/160; 214 b=(bits-1)-n*160; 215 216 for (;;) 217 { 218 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter)) 219 goto err; 220 221 /* step 7 */ 222 BN_zero(W); 223 /* now 'buf' contains "SEED + offset - 1" */ 224 for (k=0; k<=n; k++) 225 { 226 /* obtain "SEED + offset + k" by incrementing: */ 227 for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--) 228 { 229 buf[i]++; 230 if (buf[i] != 0) break; 231 } 232 233 EVP_Digest(buf,SHA_DIGEST_LENGTH,md,NULL,HASH, NULL); 234 235 /* step 8 */ 236 if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,r0)) 237 goto err; 238 if (!BN_lshift(r0,r0,160*k)) goto err; 239 if (!BN_add(W,W,r0)) goto err; 240 } 241 242 /* more of step 8 */ 243 if (!BN_mask_bits(W,bits-1)) goto err; 244 if (!BN_copy(X,W)) goto err; 245 if (!BN_add(X,X,test)) goto err; 246 247 /* step 9 */ 248 if (!BN_lshift1(r0,q)) goto err; 249 if (!BN_mod(c,X,r0,ctx)) goto err; 250 if (!BN_sub(r0,c,BN_value_one())) goto err; 251 if (!BN_sub(p,X,r0)) goto err; 252 253 /* step 10 */ 254 if (BN_cmp(p,test) >= 0) 255 { 256 /* step 11 */ 257 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, 258 ctx, 1, cb); 259 if (r > 0) 260 goto end; /* found it */ 261 if (r != 0) 262 goto err; 263 } 264 265 /* step 13 */ 266 counter++; 267 /* "offset = offset + n + 1" */ 268 269 /* step 14 */ 270 if (counter >= 4096) break; 271 } 272 } 273end: 274 if(!BN_GENCB_call(cb, 2, 1)) 275 goto err; 276 277 /* We now need to generate g */ 278 /* Set r0=(p-1)/q */ 279 if (!BN_sub(test,p,BN_value_one())) goto err; 280 if (!BN_div(r0,NULL,test,q,ctx)) goto err; 281 282 if (!BN_set_word(test,h)) goto err; 283 if (!BN_MONT_CTX_set(mont,p,ctx)) goto err; 284 285 for (;;) 286 { 287 /* g=test^r0%p */ 288 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err; 289 if (!BN_is_one(g)) break; 290 if (!BN_add(test,test,BN_value_one())) goto err; 291 h++; 292 } 293 294 if(!BN_GENCB_call(cb, 3, 1)) 295 goto err; 296 297 ok=1; 298err: 299 if (ok) 300 { 301 if(ret->p) BN_free(ret->p); 302 if(ret->q) BN_free(ret->q); 303 if(ret->g) BN_free(ret->g); 304 ret->p=BN_dup(p); 305 ret->q=BN_dup(q); 306 ret->g=BN_dup(g); 307 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) 308 { 309 ok=0; 310 goto err; 311 } 312 if (seed_in != NULL) memcpy(seed_in,seed,20); 313 if (counter_ret != NULL) *counter_ret=counter; 314 if (h_ret != NULL) *h_ret=h; 315 } 316 if(ctx) 317 { 318 BN_CTX_end(ctx); 319 BN_CTX_free(ctx); 320 } 321 if (mont != NULL) BN_MONT_CTX_free(mont); 322 return ok; 323 } 324#endif 325#endif 326