dsa_gen.c revision 1.3
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 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 SHA1 70#endif 71 72#ifndef NO_SHA 73 74#include <stdio.h> 75#include <time.h> 76#include "cryptlib.h" 77#include <openssl/sha.h> 78#include <openssl/bn.h> 79#include <openssl/dsa.h> 80#include <openssl/rand.h> 81 82DSA *DSA_generate_parameters(int bits, unsigned char *seed_in, int seed_len, 83 int *counter_ret, unsigned long *h_ret, 84 void (*callback)(int, int, void *), 85 void *cb_arg) 86 { 87 int ok=0; 88 unsigned char seed[SHA_DIGEST_LENGTH]; 89 unsigned char md[SHA_DIGEST_LENGTH]; 90 unsigned char buf[SHA_DIGEST_LENGTH],buf2[SHA_DIGEST_LENGTH]; 91 BIGNUM *r0,*W,*X,*c,*test; 92 BIGNUM *g=NULL,*q=NULL,*p=NULL; 93 BN_MONT_CTX *mont=NULL; 94 int k,n=0,i,b,m=0; 95 int counter=0; 96 int r=0; 97 BN_CTX *ctx=NULL,*ctx2=NULL,*ctx3=NULL; 98 unsigned int h=2; 99 DSA *ret=NULL; 100 101 if (bits < 512) bits=512; 102 bits=(bits+63)/64*64; 103 104 if (seed_len < 20) 105 seed_in = NULL; /* seed buffer too small -- ignore */ 106 if (seed_len > 20) 107 seed_len = 20; /* App. 2.2 of FIPS PUB 186 allows larger SEED, 108 * but our internal buffers are restricted to 160 bits*/ 109 if ((seed_in != NULL) && (seed_len == 20)) 110 memcpy(seed,seed_in,seed_len); 111 112 if ((ctx=BN_CTX_new()) == NULL) goto err; 113 if ((ctx2=BN_CTX_new()) == NULL) goto err; 114 if ((ctx3=BN_CTX_new()) == NULL) goto err; 115 if ((ret=DSA_new()) == NULL) goto err; 116 117 if ((mont=BN_MONT_CTX_new()) == NULL) goto err; 118 119 BN_CTX_start(ctx2); 120 r0 = BN_CTX_get(ctx2); 121 g = BN_CTX_get(ctx2); 122 W = BN_CTX_get(ctx2); 123 q = BN_CTX_get(ctx2); 124 X = BN_CTX_get(ctx2); 125 c = BN_CTX_get(ctx2); 126 p = BN_CTX_get(ctx2); 127 test = BN_CTX_get(ctx2); 128 129 BN_lshift(test,BN_value_one(),bits-1); 130 131 for (;;) 132 { 133 for (;;) /* find q */ 134 { 135 int seed_is_random; 136 137 /* step 1 */ 138 if (callback != NULL) callback(0,m++,cb_arg); 139 140 if (!seed_len) 141 { 142 RAND_pseudo_bytes(seed,SHA_DIGEST_LENGTH); 143 seed_is_random = 1; 144 } 145 else 146 { 147 seed_is_random = 0; 148 seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/ 149 } 150 memcpy(buf,seed,SHA_DIGEST_LENGTH); 151 memcpy(buf2,seed,SHA_DIGEST_LENGTH); 152 /* precompute "SEED + 1" for step 7: */ 153 for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--) 154 { 155 buf[i]++; 156 if (buf[i] != 0) break; 157 } 158 159 /* step 2 */ 160 HASH(seed,SHA_DIGEST_LENGTH,md); 161 HASH(buf,SHA_DIGEST_LENGTH,buf2); 162 for (i=0; i<SHA_DIGEST_LENGTH; i++) 163 md[i]^=buf2[i]; 164 165 /* step 3 */ 166 md[0]|=0x80; 167 md[SHA_DIGEST_LENGTH-1]|=0x01; 168 if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,q)) goto err; 169 170 /* step 4 */ 171 r = BN_is_prime_fasttest(q, DSS_prime_checks, callback, ctx3, cb_arg, seed_is_random); 172 if (r > 0) 173 break; 174 if (r != 0) 175 goto err; 176 177 /* do a callback call */ 178 /* step 5 */ 179 } 180 181 if (callback != NULL) callback(2,0,cb_arg); 182 if (callback != NULL) callback(3,0,cb_arg); 183 184 /* step 6 */ 185 counter=0; 186 /* "offset = 2" */ 187 188 n=(bits-1)/160; 189 b=(bits-1)-n*160; 190 191 for (;;) 192 { 193 if (callback != NULL && counter != 0) 194 callback(0,counter,cb_arg); 195 196 /* step 7 */ 197 BN_zero(W); 198 /* now 'buf' contains "SEED + offset - 1" */ 199 for (k=0; k<=n; k++) 200 { 201 /* obtain "SEED + offset + k" by incrementing: */ 202 for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--) 203 { 204 buf[i]++; 205 if (buf[i] != 0) break; 206 } 207 208 HASH(buf,SHA_DIGEST_LENGTH,md); 209 210 /* step 8 */ 211 if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,r0)) 212 goto err; 213 BN_lshift(r0,r0,160*k); 214 BN_add(W,W,r0); 215 } 216 217 /* more of step 8 */ 218 BN_mask_bits(W,bits-1); 219 BN_copy(X,W); /* this should be ok */ 220 BN_add(X,X,test); /* this should be ok */ 221 222 /* step 9 */ 223 BN_lshift1(r0,q); 224 BN_mod(c,X,r0,ctx); 225 BN_sub(r0,c,BN_value_one()); 226 BN_sub(p,X,r0); 227 228 /* step 10 */ 229 if (BN_cmp(p,test) >= 0) 230 { 231 /* step 11 */ 232 r = BN_is_prime_fasttest(p, DSS_prime_checks, callback, ctx3, cb_arg, 1); 233 if (r > 0) 234 goto end; /* found it */ 235 if (r != 0) 236 goto err; 237 } 238 239 /* step 13 */ 240 counter++; 241 /* "offset = offset + n + 1" */ 242 243 /* step 14 */ 244 if (counter >= 4096) break; 245 } 246 } 247end: 248 if (callback != NULL) callback(2,1,cb_arg); 249 250 /* We now need to generate g */ 251 /* Set r0=(p-1)/q */ 252 BN_sub(test,p,BN_value_one()); 253 BN_div(r0,NULL,test,q,ctx); 254 255 BN_set_word(test,h); 256 BN_MONT_CTX_set(mont,p,ctx); 257 258 for (;;) 259 { 260 /* g=test^r0%p */ 261 BN_mod_exp_mont(g,test,r0,p,ctx,mont); 262 if (!BN_is_one(g)) break; 263 BN_add(test,test,BN_value_one()); 264 h++; 265 } 266 267 if (callback != NULL) callback(3,1,cb_arg); 268 269 ok=1; 270err: 271 if (!ok) 272 { 273 if (ret != NULL) DSA_free(ret); 274 } 275 else 276 { 277 ret->p=BN_dup(p); 278 ret->q=BN_dup(q); 279 ret->g=BN_dup(g); 280 if ((m > 1) && (seed_in != NULL)) memcpy(seed_in,seed,20); 281 if (counter_ret != NULL) *counter_ret=counter; 282 if (h_ret != NULL) *h_ret=h; 283 } 284 if (ctx != NULL) BN_CTX_free(ctx); 285 if (ctx2 != NULL) 286 { 287 BN_CTX_end(ctx2); 288 BN_CTX_free(ctx2); 289 } 290 if (ctx3 != NULL) BN_CTX_free(ctx3); 291 if (mont != NULL) BN_MONT_CTX_free(mont); 292 return(ok?ret:NULL); 293 } 294#endif 295