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
372