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 /*
63 * Parameter generation follows the original release of FIPS PUB 186,
64 * Appendix 2.2 (i.e. use SHA as defined in FIPS PUB 180)
65 */
66 # define HASH EVP_sha()
67 #else
68 /*
69 * Parameter generation follows the updated Appendix 2.2 for FIPS PUB 186,
70 * also Appendix 2.2 of FIPS PUB 186-1 (i.e. use SHA as defined in FIPS PUB
71 * 180-1)
72 */
73 # define HASH EVP_sha1()
74 #endif
75
76 #include <openssl/opensslconf.h> /* To see if OPENSSL_NO_SHA is defined */
77
78 #ifndef OPENSSL_NO_SHA
79
80 # include <stdio.h>
81 # include "cryptlib.h"
82 # include <openssl/evp.h>
83 # include <openssl/bn.h>
84 # include <openssl/rand.h>
85 # include <openssl/sha.h>
86 # include "dsa_locl.h"
87
88 # ifdef OPENSSL_FIPS
89 # include <openssl/fips.h>
90 # endif
91
DSA_generate_parameters_ex(DSA * ret,int bits,const unsigned char * seed_in,int seed_len,int * counter_ret,unsigned long * h_ret,BN_GENCB * cb)92 int DSA_generate_parameters_ex(DSA *ret, int bits,
93 const unsigned char *seed_in, int seed_len,
94 int *counter_ret, unsigned long *h_ret,
95 BN_GENCB *cb)
96 {
97 # ifdef OPENSSL_FIPS
98 if (FIPS_mode() && !(ret->meth->flags & DSA_FLAG_FIPS_METHOD)
99 && !(ret->flags & DSA_FLAG_NON_FIPS_ALLOW)) {
100 DSAerr(DSA_F_DSA_GENERATE_PARAMETERS_EX, DSA_R_NON_FIPS_DSA_METHOD);
101 return 0;
102 }
103 # endif
104 if (ret->meth->dsa_paramgen)
105 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
106 counter_ret, h_ret, cb);
107 # ifdef OPENSSL_FIPS
108 else if (FIPS_mode()) {
109 return FIPS_dsa_generate_parameters_ex(ret, bits,
110 seed_in, seed_len,
111 counter_ret, h_ret, cb);
112 }
113 # endif
114 else {
115 const EVP_MD *evpmd;
116 size_t qbits = bits >= 2048 ? 256 : 160;
117
118 if (bits >= 2048) {
119 qbits = 256;
120 evpmd = EVP_sha256();
121 } else {
122 qbits = 160;
123 evpmd = EVP_sha1();
124 }
125
126 return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
127 seed_in, seed_len, NULL, counter_ret,
128 h_ret, cb);
129 }
130 }
131
dsa_builtin_paramgen(DSA * ret,size_t bits,size_t qbits,const EVP_MD * evpmd,const unsigned char * seed_in,size_t seed_len,unsigned char * seed_out,int * counter_ret,unsigned long * h_ret,BN_GENCB * cb)132 int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
133 const EVP_MD *evpmd, const unsigned char *seed_in,
134 size_t seed_len, 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 /*
165 * NB: seed_len == 0 is special case: copy generated seed to seed_in if
166 * it is not NULL.
167 */
168 if (seed_len && (seed_len < (size_t)qsize))
169 seed_in = NULL; /* seed buffer too small -- ignore */
170 if (seed_len > (size_t)qsize)
171 seed_len = qsize; /* App. 2.2 of FIPS PUB 186 allows larger
172 * SEED, but our internal buffers are
173 * restricted to 160 bits */
174 if (seed_in != NULL)
175 memcpy(seed, seed_in, seed_len);
176
177 if ((ctx = BN_CTX_new()) == NULL)
178 goto err;
179
180 if ((mont = BN_MONT_CTX_new()) == NULL)
181 goto err;
182
183 BN_CTX_start(ctx);
184 r0 = BN_CTX_get(ctx);
185 g = BN_CTX_get(ctx);
186 W = BN_CTX_get(ctx);
187 q = BN_CTX_get(ctx);
188 X = BN_CTX_get(ctx);
189 c = BN_CTX_get(ctx);
190 p = BN_CTX_get(ctx);
191 test = BN_CTX_get(ctx);
192
193 if (!BN_lshift(test, BN_value_one(), bits - 1))
194 goto err;
195
196 for (;;) {
197 for (;;) { /* find q */
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 if (RAND_pseudo_bytes(seed, qsize) < 0)
206 goto err;
207 seed_is_random = 1;
208 } else {
209 seed_is_random = 0;
210 seed_len = 0; /* use random seed if 'seed_in' turns out to
211 * be bad */
212 }
213 memcpy(buf, seed, qsize);
214 memcpy(buf2, seed, qsize);
215 /* precompute "SEED + 1" for step 7: */
216 for (i = qsize - 1; i >= 0; i--) {
217 buf[i]++;
218 if (buf[i] != 0)
219 break;
220 }
221
222 /* step 2 */
223 if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL))
224 goto err;
225 if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL))
226 goto err;
227 for (i = 0; i < qsize; i++)
228 md[i] ^= buf2[i];
229
230 /* step 3 */
231 md[0] |= 0x80;
232 md[qsize - 1] |= 0x01;
233 if (!BN_bin2bn(md, qsize, q))
234 goto err;
235
236 /* step 4 */
237 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
238 seed_is_random, cb);
239 if (r > 0)
240 break;
241 if (r != 0)
242 goto err;
243
244 /* do a callback call */
245 /* step 5 */
246 }
247
248 if (!BN_GENCB_call(cb, 2, 0))
249 goto err;
250 if (!BN_GENCB_call(cb, 3, 0))
251 goto err;
252
253 /* step 6 */
254 counter = 0;
255 /* "offset = 2" */
256
257 n = (bits - 1) / 160;
258
259 for (;;) {
260 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
261 goto err;
262
263 /* step 7 */
264 BN_zero(W);
265 /* now 'buf' contains "SEED + offset - 1" */
266 for (k = 0; k <= n; k++) {
267 /*
268 * obtain "SEED + offset + k" by incrementing:
269 */
270 for (i = qsize - 1; i >= 0; i--) {
271 buf[i]++;
272 if (buf[i] != 0)
273 break;
274 }
275
276 if (!EVP_Digest(buf, qsize, md, NULL, evpmd, NULL))
277 goto err;
278
279 /* step 8 */
280 if (!BN_bin2bn(md, qsize, r0))
281 goto err;
282 if (!BN_lshift(r0, r0, (qsize << 3) * k))
283 goto err;
284 if (!BN_add(W, W, r0))
285 goto err;
286 }
287
288 /* more of step 8 */
289 if (!BN_mask_bits(W, bits - 1))
290 goto err;
291 if (!BN_copy(X, W))
292 goto err;
293 if (!BN_add(X, X, test))
294 goto err;
295
296 /* step 9 */
297 if (!BN_lshift1(r0, q))
298 goto err;
299 if (!BN_mod(c, X, r0, ctx))
300 goto err;
301 if (!BN_sub(r0, c, BN_value_one()))
302 goto err;
303 if (!BN_sub(p, X, r0))
304 goto err;
305
306 /* step 10 */
307 if (BN_cmp(p, test) >= 0) {
308 /* step 11 */
309 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb);
310 if (r > 0)
311 goto end; /* found it */
312 if (r != 0)
313 goto err;
314 }
315
316 /* step 13 */
317 counter++;
318 /* "offset = offset + n + 1" */
319
320 /* step 14 */
321 if (counter >= 4096)
322 break;
323 }
324 }
325 end:
326 if (!BN_GENCB_call(cb, 2, 1))
327 goto err;
328
329 /* We now need to generate g */
330 /* Set r0=(p-1)/q */
331 if (!BN_sub(test, p, BN_value_one()))
332 goto err;
333 if (!BN_div(r0, NULL, test, q, ctx))
334 goto err;
335
336 if (!BN_set_word(test, h))
337 goto err;
338 if (!BN_MONT_CTX_set(mont, p, ctx))
339 goto err;
340
341 for (;;) {
342 /* g=test^r0%p */
343 if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont))
344 goto err;
345 if (!BN_is_one(g))
346 break;
347 if (!BN_add(test, test, BN_value_one()))
348 goto err;
349 h++;
350 }
351
352 if (!BN_GENCB_call(cb, 3, 1))
353 goto err;
354
355 ok = 1;
356 err:
357 if (ok) {
358 if (ret->p)
359 BN_free(ret->p);
360 if (ret->q)
361 BN_free(ret->q);
362 if (ret->g)
363 BN_free(ret->g);
364 ret->p = BN_dup(p);
365 ret->q = BN_dup(q);
366 ret->g = BN_dup(g);
367 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
368 ok = 0;
369 goto err;
370 }
371 if (counter_ret != NULL)
372 *counter_ret = counter;
373 if (h_ret != NULL)
374 *h_ret = h;
375 if (seed_out)
376 memcpy(seed_out, seed, qsize);
377 }
378 if (ctx) {
379 BN_CTX_end(ctx);
380 BN_CTX_free(ctx);
381 }
382 if (mont != NULL)
383 BN_MONT_CTX_free(mont);
384 return ok;
385 }
386 #endif
387