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