dsa_gen.c revision 1.1
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#define HASH SHA 63#else 64#define HASH SHA1 65#endif 66 67#include <stdio.h> 68#include <time.h> 69#include "cryptlib.h" 70#include "sha.h" 71#include "bn.h" 72#include "dsa.h" 73#include "rand.h" 74 75DSA *DSA_generate_parameters(bits,seed_in,seed_len,counter_ret,h_ret,callback, 76 cb_arg) 77int bits; 78unsigned char *seed_in; 79int seed_len; 80int *counter_ret; 81unsigned long *h_ret; 82void (*callback)(); 83char *cb_arg; 84 { 85 int ok=0; 86 unsigned char seed[SHA_DIGEST_LENGTH]; 87 unsigned char md[SHA_DIGEST_LENGTH]; 88 unsigned char buf[SHA_DIGEST_LENGTH],buf2[SHA_DIGEST_LENGTH]; 89 BIGNUM *r0,*W,*X,*c,*test; 90 BIGNUM *g=NULL,*q=NULL,*p=NULL; 91 int k,n=0,i,b,m=0; 92 int counter=0; 93 BN_CTX *ctx=NULL,*ctx2=NULL; 94 unsigned int h=2; 95 DSA *ret=NULL; 96 97 if (bits < 512) bits=512; 98 bits=(bits+63)/64*64; 99 100 if ((seed_in != NULL) && (seed_len == 20)) 101 memcpy(seed,seed_in,seed_len); 102 103 ctx=BN_CTX_new(); 104 if (ctx == NULL) goto err; 105 ctx2=BN_CTX_new(); 106 if (ctx2 == NULL) goto err; 107 ret=DSA_new(); 108 if (ret == NULL) goto err; 109 r0=ctx2->bn[0]; 110 g=ctx2->bn[1]; 111 W=ctx2->bn[2]; 112 q=ctx2->bn[3]; 113 X=ctx2->bn[4]; 114 c=ctx2->bn[5]; 115 p=ctx2->bn[6]; 116 test=ctx2->bn[7]; 117 118 BN_lshift(test,BN_value_one(),bits-1); 119 120 for (;;) 121 { 122 for (;;) 123 { 124 /* step 1 */ 125 if (callback != NULL) callback(0,m++,cb_arg); 126 127 if (!seed_len) 128 RAND_bytes(seed,SHA_DIGEST_LENGTH); 129 else 130 seed_len=0; 131 132 memcpy(buf,seed,SHA_DIGEST_LENGTH); 133 memcpy(buf2,seed,SHA_DIGEST_LENGTH); 134 for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--) 135 { 136 buf[i]++; 137 if (buf[i] != 0) break; 138 } 139 140 /* step 2 */ 141 HASH(seed,SHA_DIGEST_LENGTH,md); 142 HASH(buf,SHA_DIGEST_LENGTH,buf2); 143 for (i=0; i<SHA_DIGEST_LENGTH; i++) 144 md[i]^=buf2[i]; 145 146 /* step 3 */ 147 md[0]|=0x80; 148 md[SHA_DIGEST_LENGTH-1]|=0x01; 149 if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,q)) abort(); 150 151 /* step 4 */ 152 if (DSA_is_prime(q,callback,cb_arg) > 0) break; 153 /* do a callback call */ 154 /* step 5 */ 155 } 156 157 if (callback != NULL) callback(2,0,cb_arg); 158 if (callback != NULL) callback(3,0,cb_arg); 159 160 /* step 6 */ 161 counter=0; 162 163 n=(bits-1)/160; 164 b=(bits-1)-n*160; 165 166 for (;;) 167 { 168 /* step 7 */ 169 BN_zero(W); 170 for (k=0; k<=n; k++) 171 { 172 for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--) 173 { 174 buf[i]++; 175 if (buf[i] != 0) break; 176 } 177 178 HASH(buf,SHA_DIGEST_LENGTH,md); 179 180 /* step 8 */ 181 if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,r0)) abort(); 182 BN_lshift(r0,r0,160*k); 183 BN_add(W,W,r0); 184 } 185 186 /* more of step 8 */ 187 BN_mask_bits(W,bits-1); 188 BN_copy(X,W); /* this should be ok */ 189 BN_add(X,X,test); /* this should be ok */ 190 191 /* step 9 */ 192 BN_lshift1(r0,q); 193 BN_mod(c,X,r0,ctx); 194 BN_sub(r0,c,BN_value_one()); 195 BN_sub(p,X,r0); 196 197 /* step 10 */ 198 if (BN_cmp(p,test) >= 0) 199 { 200 /* step 11 */ 201 if (DSA_is_prime(p,callback,cb_arg) > 0) 202 goto end; 203 } 204 205 /* step 13 */ 206 counter++; 207 208 /* step 14 */ 209 if (counter >= 4096) break; 210 211 if (callback != NULL) callback(0,counter,cb_arg); 212 } 213 } 214end: 215 if (callback != NULL) callback(2,1,cb_arg); 216 217 /* We now need to gernerate g */ 218 /* Set r0=(p-1)/q */ 219 BN_sub(test,p,BN_value_one()); 220 BN_div(r0,NULL,test,q,ctx); 221 222 BN_set_word(test,h); 223 for (;;) 224 { 225 /* g=test^r0%p */ 226 BN_mod_exp(g,test,r0,p,ctx); 227 if (!BN_is_one(g)) break; 228 BN_add(test,test,BN_value_one()); 229 h++; 230 } 231 232 if (callback != NULL) callback(3,1,cb_arg); 233 234 ok=1; 235err: 236 if (!ok) 237 { 238 if (ret != NULL) DSA_free(ret); 239 } 240 else 241 { 242 ret->p=BN_dup(p); 243 ret->q=BN_dup(q); 244 ret->g=BN_dup(g); 245 if ((m > 1) && (seed_in != NULL)) memcpy(seed_in,seed,20); 246 if (counter_ret != NULL) *counter_ret=counter; 247 if (h_ret != NULL) *h_ret=h; 248 } 249 BN_CTX_free(ctx); 250 BN_CTX_free(ctx2); 251 return(ok?ret:NULL); 252 } 253 254int DSA_is_prime(w, callback,cb_arg) 255BIGNUM *w; 256void (*callback)(); 257char *cb_arg; 258 { 259 int ok= -1,j,i,n; 260 BN_CTX *ctx=NULL,*ctx2=NULL; 261 BIGNUM *w_1,*b,*m,*z; 262 int a; 263 264 if (!BN_is_bit_set(w,0)) return(0); 265 266 ctx=BN_CTX_new(); 267 if (ctx == NULL) goto err; 268 ctx2=BN_CTX_new(); 269 if (ctx2 == NULL) goto err; 270 271 m= ctx2->bn[2]; 272 b= ctx2->bn[3]; 273 z= ctx2->bn[4]; 274 w_1=ctx2->bn[5]; 275 276 /* step 1 */ 277 n=50; 278 279 /* step 2 */ 280 if (!BN_sub(w_1,w,BN_value_one())) goto err; 281 for (a=1; !BN_is_bit_set(w_1,a); a++) 282 ; 283 if (!BN_rshift(m,w_1,a)) goto err; 284 285 for (i=1; i < n; i++) 286 { 287 /* step 3 */ 288 BN_rand(b,BN_num_bits(w)-2/*-1*/,0,0); 289 BN_set_word(b,0x10001L); 290 291 /* step 4 */ 292 j=0; 293 if (!BN_mod_exp(z,b,m,w,ctx)) goto err; 294 295 /* step 5 */ 296 for (;;) 297 { 298 if (((j == 0) && BN_is_one(z)) || (BN_cmp(z,w_1) == 0)) 299 break; 300 301 /* step 6 */ 302 if ((j > 0) && BN_is_one(z)) 303 { 304 ok=0; 305 goto err; 306 } 307 308 j++; 309 if (j >= a) 310 { 311 ok=0; 312 goto err; 313 } 314 315 if (!BN_mod_mul(z,z,z,w,ctx)) goto err; 316 if (callback != NULL) callback(1,j,cb_arg); 317 } 318 } 319 320 ok=1; 321err: 322 if (ok == -1) DSAerr(DSA_F_DSA_IS_PRIME,ERR_R_BN_LIB); 323 BN_CTX_free(ctx); 324 BN_CTX_free(ctx2); 325 326 return(ok); 327 } 328 329