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 "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
84 #ifdef OPENSSL_FIPS
85 #include <openssl/fips.h>
86 #endif
87
88 int DSA_generate_parameters_ex(DSA *ret, int bits,
89 const unsigned char *seed_in, int seed_len,
90 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
91 {
92 #ifdef OPENSSL_FIPS
93 if (FIPS_mode() && !(ret->meth->flags & DSA_FLAG_FIPS_METHOD)
94 && !(ret->flags & DSA_FLAG_NON_FIPS_ALLOW))
95 {
96 DSAerr(DSA_F_DSA_GENERATE_PARAMETERS_EX, DSA_R_NON_FIPS_DSA_METHOD);
97 return 0;
98 }
99 #endif
100 if(ret->meth->dsa_paramgen)
101 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
102 counter_ret, h_ret, cb);
103 #ifdef OPENSSL_FIPS
104 else if (FIPS_mode())
105 {
106 return FIPS_dsa_generate_parameters_ex(ret, bits,
107 seed_in, seed_len,
108 counter_ret, h_ret, cb);
109 }
110 #endif
111 else
112 {
113 const EVP_MD *evpmd;
114 size_t qbits = bits >= 2048 ? 256 : 160;
115
116 if (bits >= 2048)
117 {
118 qbits = 256;
119 evpmd = EVP_sha256();
120 }
121 else
122 {
123 qbits = 160;
124 evpmd = EVP_sha1();
125 }
126
127 return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
128 seed_in, seed_len, NULL, counter_ret, h_ret, cb);
129 }
130 }
131
132 int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
133 const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
134 unsigned char *seed_out,
135 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
136 {
137 int ok=0;
138 unsigned char seed[SHA256_DIGEST_LENGTH];
139 unsigned char md[SHA256_DIGEST_LENGTH];
140 unsigned char buf[SHA256_DIGEST_LENGTH],buf2[SHA256_DIGEST_LENGTH];
141 BIGNUM *r0,*W,*X,*c,*test;
142 BIGNUM *g=NULL,*q=NULL,*p=NULL;
143 BN_MONT_CTX *mont=NULL;
144 int i, k, n=0, m=0, qsize = qbits >> 3;
145 int counter=0;
146 int r=0;
147 BN_CTX *ctx=NULL;
148 unsigned int h=2;
149
150 if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
151 qsize != SHA256_DIGEST_LENGTH)
152 /* invalid q size */
153 return 0;
154
155 if (evpmd == NULL)
156 /* use SHA1 as default */
157 evpmd = EVP_sha1();
158
159 if (bits < 512)
160 bits = 512;
161
162 bits = (bits+63)/64*64;
163
164 /* NB: seed_len == 0 is special case: copy generated seed to
165 * seed_in if it is not NULL.
166 */
167 if (seed_len && (seed_len < (size_t)qsize))
168 seed_in = NULL; /* seed buffer too small -- ignore */
169 if (seed_len > (size_t)qsize)
170 seed_len = qsize; /* App. 2.2 of FIPS PUB 186 allows larger SEED,
171 * but our internal buffers are restricted to 160 bits*/
172 if (seed_in != NULL)
173 memcpy(seed, seed_in, seed_len);
174
175 if ((ctx=BN_CTX_new()) == NULL)
176 goto err;
177
178 if ((mont=BN_MONT_CTX_new()) == NULL)
179 goto err;
180
181 BN_CTX_start(ctx);
182 r0 = BN_CTX_get(ctx);
183 g = BN_CTX_get(ctx);
184 W = BN_CTX_get(ctx);
185 q = BN_CTX_get(ctx);
186 X = BN_CTX_get(ctx);
187 c = BN_CTX_get(ctx);
188 p = BN_CTX_get(ctx);
189 test = BN_CTX_get(ctx);
190
191 if (!BN_lshift(test,BN_value_one(),bits-1))
192 goto err;
193
194 for (;;)
195 {
196 for (;;) /* find q */
197 {
198 int seed_is_random;
199
200 /* step 1 */
201 if(!BN_GENCB_call(cb, 0, m++))
202 goto err;
203
204 if (!seed_len)
205 {
206 RAND_pseudo_bytes(seed, qsize);
207 seed_is_random = 1;
208 }
209 else
210 {
211 seed_is_random = 0;
212 seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/
213 }
214 memcpy(buf , seed, qsize);
215 memcpy(buf2, seed, qsize);
216 /* precompute "SEED + 1" for step 7: */
217 for (i = qsize-1; i >= 0; i--)
218 {
219 buf[i]++;
220 if (buf[i] != 0)
221 break;
222 }
223
224 /* step 2 */
225 if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL))
226 goto err;
227 if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL))
228 goto err;
229 for (i = 0; i < qsize; i++)
230 md[i]^=buf2[i];
231
232 /* step 3 */
233 md[0] |= 0x80;
234 md[qsize-1] |= 0x01;
235 if (!BN_bin2bn(md, qsize, q))
236 goto err;
237
238 /* step 4 */
239 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
240 seed_is_random, cb);
241 if (r > 0)
242 break;
243 if (r != 0)
244 goto err;
245
246 /* do a callback call */
247 /* step 5 */
248 }
249
250 if(!BN_GENCB_call(cb, 2, 0)) goto err;
251 if(!BN_GENCB_call(cb, 3, 0)) goto err;
252
253 /* step 6 */
254 counter=0;
255 /* "offset = 2" */
256
257 n=(bits-1)/160;
258
259 for (;;)
260 {
261 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
262 goto err;
263
264 /* step 7 */
265 BN_zero(W);
266 /* now 'buf' contains "SEED + offset - 1" */
267 for (k=0; k<=n; k++)
268 {
269 /* obtain "SEED + offset + k" by incrementing: */
270 for (i = qsize-1; i >= 0; i--)
271 {
272 buf[i]++;
273 if (buf[i] != 0)
274 break;
275 }
276
277 if (!EVP_Digest(buf, qsize, md ,NULL, evpmd,
278 NULL))
279 goto err;
280
281 /* step 8 */
282 if (!BN_bin2bn(md, qsize, r0))
283 goto err;
284 if (!BN_lshift(r0,r0,(qsize << 3)*k)) goto err;
285 if (!BN_add(W,W,r0)) goto err;
286 }
287
288 /* more of step 8 */
289 if (!BN_mask_bits(W,bits-1)) goto err;
290 if (!BN_copy(X,W)) goto err;
291 if (!BN_add(X,X,test)) goto err;
292
293 /* step 9 */
294 if (!BN_lshift1(r0,q)) goto err;
295 if (!BN_mod(c,X,r0,ctx)) goto err;
296 if (!BN_sub(r0,c,BN_value_one())) goto err;
297 if (!BN_sub(p,X,r0)) goto err;
298
299 /* step 10 */
300 if (BN_cmp(p,test) >= 0)
301 {
302 /* step 11 */
303 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
304 ctx, 1, cb);
305 if (r > 0)
306 goto end; /* found it */
307 if (r != 0)
308 goto err;
309 }
310
311 /* step 13 */
312 counter++;
313 /* "offset = offset + n + 1" */
314
315 /* step 14 */
316 if (counter >= 4096) break;
317 }
318 }
319 end:
320 if(!BN_GENCB_call(cb, 2, 1))
321 goto err;
322
323 /* We now need to generate g */
324 /* Set r0=(p-1)/q */
325 if (!BN_sub(test,p,BN_value_one())) goto err;
326 if (!BN_div(r0,NULL,test,q,ctx)) goto err;
327
328 if (!BN_set_word(test,h)) goto err;
329 if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
330
331 for (;;)
332 {
333 /* g=test^r0%p */
334 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
335 if (!BN_is_one(g)) break;
336 if (!BN_add(test,test,BN_value_one())) goto err;
337 h++;
338 }
339
340 if(!BN_GENCB_call(cb, 3, 1))
341 goto err;
342
343 ok=1;
344 err:
345 if (ok)
346 {
347 if(ret->p) BN_free(ret->p);
348 if(ret->q) BN_free(ret->q);
349 if(ret->g) BN_free(ret->g);
350 ret->p=BN_dup(p);
351 ret->q=BN_dup(q);
352 ret->g=BN_dup(g);
353 if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
354 {
355 ok=0;
356 goto err;
357 }
358 if (counter_ret != NULL) *counter_ret=counter;
359 if (h_ret != NULL) *h_ret=h;
360 if (seed_out)
361 memcpy(seed_out, seed, qsize);
362 }
363 if(ctx)
364 {
365 BN_CTX_end(ctx);
366 BN_CTX_free(ctx);
367 }
368 if (mont != NULL) BN_MONT_CTX_free(mont);
369 return ok;
370 }
371 #endif