1 /* crypto/dsa/dsa_gen.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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.
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).
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.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
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)"
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
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.]
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)
66 # define HASH EVP_sha()
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
73 # define HASH EVP_sha1()
76 #include <openssl/opensslconf.h> /* To see if OPENSSL_NO_SHA is defined */
78 #ifndef OPENSSL_NO_SHA
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"
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,
93 if (ret->meth->dsa_paramgen)
94 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
95 counter_ret, h_ret, cb);
98 size_t qbits = bits >= 2048 ? 256 : 160;
102 evpmd = EVP_sha256();
108 return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
109 seed_in, seed_len, counter_ret, h_ret,
114 int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
115 const EVP_MD *evpmd, const unsigned char *seed_in,
116 size_t seed_len, int *counter_ret,
117 unsigned long *h_ret, BN_GENCB *cb)
120 unsigned char seed[SHA256_DIGEST_LENGTH];
121 unsigned char md[SHA256_DIGEST_LENGTH];
122 unsigned char buf[SHA256_DIGEST_LENGTH], buf2[SHA256_DIGEST_LENGTH];
123 BIGNUM *r0, *W, *X, *c, *test;
124 BIGNUM *g = NULL, *q = NULL, *p = NULL;
125 BN_MONT_CTX *mont = NULL;
126 int i, k, n = 0, m = 0, qsize = qbits >> 3;
132 if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
133 qsize != SHA256_DIGEST_LENGTH)
138 /* use SHA1 as default */
144 bits = (bits + 63) / 64 * 64;
147 * NB: seed_len == 0 is special case: copy generated seed to seed_in if
150 if (seed_len && (seed_len < (size_t)qsize))
151 seed_in = NULL; /* seed buffer too small -- ignore */
152 if (seed_len > (size_t)qsize)
153 seed_len = qsize; /* App. 2.2 of FIPS PUB 186 allows larger
154 * SEED, but our internal buffers are
155 * restricted to 160 bits */
157 memcpy(seed, seed_in, seed_len);
159 if ((ctx = BN_CTX_new()) == NULL)
162 if ((mont = BN_MONT_CTX_new()) == NULL)
166 r0 = BN_CTX_get(ctx);
173 test = BN_CTX_get(ctx);
175 if (!BN_lshift(test, BN_value_one(), bits - 1))
179 for (;;) { /* find q */
183 if (!BN_GENCB_call(cb, 0, m++))
187 RAND_pseudo_bytes(seed, qsize);
191 seed_len = 0; /* use random seed if 'seed_in' turns out to
194 memcpy(buf, seed, qsize);
195 memcpy(buf2, seed, qsize);
196 /* precompute "SEED + 1" for step 7: */
197 for (i = qsize - 1; i >= 0; i--) {
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++)
211 md[qsize - 1] |= 0x01;
212 if (!BN_bin2bn(md, qsize, q))
216 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
223 /* do a callback call */
227 if (!BN_GENCB_call(cb, 2, 0))
229 if (!BN_GENCB_call(cb, 3, 0))
236 n = (bits - 1) / 160;
239 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
244 /* now 'buf' contains "SEED + offset - 1" */
245 for (k = 0; k <= n; k++) {
247 * obtain "SEED + offset + k" by incrementing:
249 for (i = qsize - 1; i >= 0; i--) {
255 EVP_Digest(buf, qsize, md, NULL, evpmd, NULL);
258 if (!BN_bin2bn(md, qsize, r0))
260 if (!BN_lshift(r0, r0, (qsize << 3) * k))
262 if (!BN_add(W, W, r0))
267 if (!BN_mask_bits(W, bits - 1))
271 if (!BN_add(X, X, test))
275 if (!BN_lshift1(r0, q))
277 if (!BN_mod(c, X, r0, ctx))
279 if (!BN_sub(r0, c, BN_value_one()))
281 if (!BN_sub(p, X, r0))
285 if (BN_cmp(p, test) >= 0) {
287 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb);
289 goto end; /* found it */
296 /* "offset = offset + n + 1" */
304 if (!BN_GENCB_call(cb, 2, 1))
307 /* We now need to generate g */
309 if (!BN_sub(test, p, BN_value_one()))
311 if (!BN_div(r0, NULL, test, q, ctx))
314 if (!BN_set_word(test, h))
316 if (!BN_MONT_CTX_set(mont, p, ctx))
321 if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont))
325 if (!BN_add(test, test, BN_value_one()))
330 if (!BN_GENCB_call(cb, 3, 1))
345 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
349 if (counter_ret != NULL)
350 *counter_ret = counter;
359 BN_MONT_CTX_free(mont);