GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libcrypto/dsa/dsa_gen.c Lines: 114 164 69.5 %
Date: 2017-11-13 Branches: 84 146 57.5 %

Line Branch Exec Source
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/* $OpenBSD: dsa_gen.c,v 1.24 2017/01/21 10:38:29 beck Exp $ */
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
#include <openssl/opensslconf.h> /* To see if OPENSSL_NO_SHA is defined */
60
61
#ifndef OPENSSL_NO_SHA
62
63
#include <stdio.h>
64
#include <stdlib.h>
65
#include <string.h>
66
67
#include <openssl/bn.h>
68
#include <openssl/evp.h>
69
#include <openssl/sha.h>
70
71
#include "bn_lcl.h"
72
#include "dsa_locl.h"
73
74
int
75
DSA_generate_parameters_ex(DSA *ret, int bits, const unsigned char *seed_in,
76
    int seed_len, int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
77
{
78
20
	if (ret->meth->dsa_paramgen)
79
		return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
80
		    counter_ret, h_ret, cb);
81
	else {
82
		const EVP_MD *evpmd;
83
		size_t qbits;
84
85
10
		if (bits >= 2048) {
86
			qbits = 256;
87
			evpmd = EVP_sha256();
88
		} else {
89
			qbits = 160;
90
10
			evpmd = EVP_sha1();
91
		}
92
93
20
		return dsa_builtin_paramgen(ret, bits, qbits, evpmd, seed_in,
94
10
		    seed_len, NULL, counter_ret, h_ret, cb);
95
	}
96
10
}
97
98
int
99
dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits, const EVP_MD *evpmd,
100
    const unsigned char *seed_in, size_t seed_len, unsigned char *seed_out,
101
    int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
102
{
103
	int ok = 0;
104
24
	unsigned char seed[SHA256_DIGEST_LENGTH];
105
12
	unsigned char md[SHA256_DIGEST_LENGTH];
106
12
	unsigned char buf[SHA256_DIGEST_LENGTH], buf2[SHA256_DIGEST_LENGTH];
107
	BIGNUM *r0, *W, *X, *c, *test;
108
	BIGNUM *g = NULL, *q = NULL, *p = NULL;
109
	BN_MONT_CTX *mont = NULL;
110
12
	int i, k, n = 0, m = 0, qsize = qbits >> 3;
111
	int counter = 0;
112
	int r = 0;
113
	BN_CTX *ctx = NULL;
114
	unsigned int h = 2;
115
116
24
	if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
117
12
	    qsize != SHA256_DIGEST_LENGTH)
118
		/* invalid q size */
119
		return 0;
120
121
12
	if (evpmd == NULL)
122
		/* use SHA1 as default */
123
2
		evpmd = EVP_sha1();
124
125
12
	if (bits < 512)
126
		bits = 512;
127
128
12
	bits = (bits + 63) / 64 * 64;
129
130
12
	if (seed_len < (size_t)qsize) {
131
		seed_in = NULL;		/* seed buffer too small -- ignore */
132
		seed_len = 0;
133
6
	}
134
	/*
135
	 * App. 2.2 of FIPS PUB 186 allows larger SEED,
136
	 * but our internal buffers are restricted to 160 bits
137
	 */
138
12
	if (seed_len > (size_t)qsize)
139
		seed_len = qsize;
140
12
	if (seed_in != NULL)
141
6
		memcpy(seed, seed_in, seed_len);
142
6
	else if (seed_len != 0)
143
		goto err;
144
145
12
	if ((mont=BN_MONT_CTX_new()) == NULL)
146
		goto err;
147
148
12
	if ((ctx=BN_CTX_new()) == NULL)
149
		goto err;
150
12
	BN_CTX_start(ctx);
151
152
12
	if ((r0 = BN_CTX_get(ctx)) == NULL)
153
		goto err;
154
12
	if ((g = BN_CTX_get(ctx)) == NULL)
155
		goto err;
156
12
	if ((W = BN_CTX_get(ctx)) == NULL)
157
		goto err;
158
12
	if ((q = BN_CTX_get(ctx)) == NULL)
159
		goto err;
160
12
	if ((X = BN_CTX_get(ctx)) == NULL)
161
		goto err;
162
12
	if ((c = BN_CTX_get(ctx)) == NULL)
163
		goto err;
164
12
	if ((p = BN_CTX_get(ctx)) == NULL)
165
		goto err;
166
12
	if ((test = BN_CTX_get(ctx)) == NULL)
167
		goto err;
168
169
12
	if (!BN_lshift(test, BN_value_one(), bits - 1))
170
		goto err;
171
172
12
	for (;;) {
173
161
		for (;;) { /* find q */
174
			int seed_is_random;
175
176
			/* step 1 */
177
161
			if (!BN_GENCB_call(cb, 0, m++))
178
				goto err;
179
180
161
			if (seed_len == 0) {
181
155
				arc4random_buf(seed, qsize);
182
				seed_is_random = 1;
183
155
			} else {
184
				seed_is_random = 0;
185
				/* use random seed if 'seed_in' turns out
186
				   to be bad */
187
				seed_len = 0;
188
			}
189
161
			memcpy(buf, seed, qsize);
190
161
			memcpy(buf2, seed, qsize);
191
			/* precompute "SEED + 1" for step 7: */
192
322
			for (i = qsize - 1; i >= 0; i--) {
193
161
				buf[i]++;
194
161
				if (buf[i] != 0)
195
					break;
196
			}
197
198
			/* step 2 */
199
161
			if (!EVP_Digest(seed, qsize, md,   NULL, evpmd, NULL))
200
				goto err;
201
161
			if (!EVP_Digest(buf,  qsize, buf2, NULL, evpmd, NULL))
202
				goto err;
203
6762
			for (i = 0; i < qsize; i++)
204
3220
				md[i] ^= buf2[i];
205
206
			/* step 3 */
207
161
			md[0] |= 0x80;
208
161
			md[qsize - 1] |= 0x01;
209
161
			if (!BN_bin2bn(md, qsize, q))
210
				goto err;
211
212
			/* step 4 */
213
161
			r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
214
			    seed_is_random, cb);
215
161
			if (r > 0)
216
12
				break;
217
149
			if (r != 0)
218
				goto err;
219
220
			/* do a callback call */
221
			/* step 5 */
222

149
		}
223
224
12
		if (!BN_GENCB_call(cb, 2, 0))
225
			goto err;
226
12
		if (!BN_GENCB_call(cb, 3, 0))
227
			goto err;
228
229
		/* step 6 */
230
		counter = 0;
231
		/* "offset = 2" */
232
233
12
		n = (bits - 1) / 160;
234
235
1921
		for (;;) {
236

3830
			if (counter != 0 && !BN_GENCB_call(cb, 0, counter))
237
				goto err;
238
239
			/* step 7 */
240
1921
			BN_zero(W);
241
			/* now 'buf' contains "SEED + offset - 1" */
242
23350
			for (k = 0; k <= n; k++) {
243
				/* obtain "SEED + offset + k" by incrementing: */
244
19594
				for (i = qsize - 1; i >= 0; i--) {
245
9797
					buf[i]++;
246
9797
					if (buf[i] != 0)
247
						break;
248
				}
249
250
9754
				if (!EVP_Digest(buf, qsize, md ,NULL, evpmd,
251
				    NULL))
252
					goto err;
253
254
				/* step 8 */
255
9754
				if (!BN_bin2bn(md, qsize, r0))
256
					goto err;
257
9754
				if (!BN_lshift(r0, r0, (qsize << 3) * k))
258
					goto err;
259
9754
				if (!BN_add(W, W, r0))
260
					goto err;
261
			}
262
263
			/* more of step 8 */
264
1921
			if (!BN_mask_bits(W, bits - 1))
265
				goto err;
266
1921
			if (!BN_copy(X, W))
267
				goto err;
268
1921
			if (!BN_add(X, X, test))
269
				goto err;
270
271
			/* step 9 */
272
1921
			if (!BN_lshift1(r0, q))
273
				goto err;
274
1921
			if (!BN_mod_ct(c, X, r0, ctx))
275
				goto err;
276
1921
			if (!BN_sub(r0, c, BN_value_one()))
277
				goto err;
278
1921
			if (!BN_sub(p, X, r0))
279
				goto err;
280
281
			/* step 10 */
282
1921
			if (BN_cmp(p, test) >= 0) {
283
				/* step 11 */
284
1921
				r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
285
				    ctx, 1, cb);
286
1921
				if (r > 0)
287
					goto end; /* found it */
288
1909
				if (r != 0)
289
					goto err;
290
			}
291
292
			/* step 13 */
293
1909
			counter++;
294
			/* "offset = offset + n + 1" */
295
296
			/* step 14 */
297
1909
			if (counter >= 4096)
298
				break;
299
		}
300
	}
301
end:
302
12
	if (!BN_GENCB_call(cb, 2, 1))
303
		goto err;
304
305
	/* We now need to generate g */
306
	/* Set r0=(p-1)/q */
307
12
	if (!BN_sub(test, p, BN_value_one()))
308
		goto err;
309
12
	if (!BN_div_ct(r0, NULL, test, q, ctx))
310
		goto err;
311
312
12
	if (!BN_set_word(test, h))
313
		goto err;
314
12
	if (!BN_MONT_CTX_set(mont, p, ctx))
315
		goto err;
316
317
12
	for (;;) {
318
		/* g=test^r0%p */
319
12
		if (!BN_mod_exp_mont_ct(g, test, r0, p, ctx, mont))
320
			goto err;
321

12
		if (!BN_is_one(g))
322
			break;
323
		if (!BN_add(test, test, BN_value_one()))
324
			goto err;
325
		h++;
326
	}
327
328
12
	if (!BN_GENCB_call(cb, 3, 1))
329
		goto err;
330
331
12
	ok = 1;
332
err:
333
12
	if (ok) {
334
12
		BN_free(ret->p);
335
12
		BN_free(ret->q);
336
12
		BN_free(ret->g);
337
12
		ret->p = BN_dup(p);
338
12
		ret->q = BN_dup(q);
339
12
		ret->g = BN_dup(g);
340

36
		if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
341
			ok = 0;
342
			goto err;
343
		}
344
12
		if (counter_ret != NULL)
345
6
			*counter_ret = counter;
346
12
		if (h_ret != NULL)
347
6
			*h_ret = h;
348
12
		if (seed_out != NULL)
349
			memcpy(seed_out, seed, qsize);
350
	}
351
12
	if (ctx) {
352
12
		BN_CTX_end(ctx);
353
12
		BN_CTX_free(ctx);
354
12
	}
355
12
	BN_MONT_CTX_free(mont);
356
12
	return ok;
357
12
}
358
#endif