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