dsa_gen.c revision 280304 
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
92int 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
132int 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                RAND_pseudo_bytes(seed, qsize);
206                seed_is_random = 1;
207            } else {
208                seed_is_random = 0;
209                seed_len = 0;   /* use random seed if 'seed_in' turns out to
210                                 * be bad */
211            }
212            memcpy(buf, seed, qsize);
213            memcpy(buf2, seed, qsize);
214            /* precompute "SEED + 1" for step 7: */
215            for (i = qsize - 1; i >= 0; i--) {
216                buf[i]++;
217                if (buf[i] != 0)
218                    break;
219            }
220
221            /* step 2 */
222            if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL))
223                goto err;
224            if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL))
225                goto err;
226            for (i = 0; i < qsize; i++)
227                md[i] ^= buf2[i];
228
229            /* step 3 */
230            md[0] |= 0x80;
231            md[qsize - 1] |= 0x01;
232            if (!BN_bin2bn(md, qsize, q))
233                goto err;
234
235            /* step 4 */
236            r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
237                                        seed_is_random, cb);
238            if (r > 0)
239                break;
240            if (r != 0)
241                goto err;
242
243            /* do a callback call */
244            /* step 5 */
245        }
246
247        if (!BN_GENCB_call(cb, 2, 0))
248            goto err;
249        if (!BN_GENCB_call(cb, 3, 0))
250            goto err;
251
252        /* step 6 */
253        counter = 0;
254        /* "offset = 2" */
255
256        n = (bits - 1) / 160;
257
258        for (;;) {
259            if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
260                goto err;
261
262            /* step 7 */
263            BN_zero(W);
264            /* now 'buf' contains "SEED + offset - 1" */
265            for (k = 0; k <= n; k++) {
266                /*
267                 * obtain "SEED + offset + k" by incrementing:
268                 */
269                for (i = qsize - 1; i >= 0; i--) {
270                    buf[i]++;
271                    if (buf[i] != 0)
272                        break;
273                }
274
275                if (!EVP_Digest(buf, qsize, md, NULL, evpmd, NULL))
276                    goto err;
277
278                /* step 8 */
279                if (!BN_bin2bn(md, qsize, r0))
280                    goto err;
281                if (!BN_lshift(r0, r0, (qsize << 3) * k))
282                    goto err;
283                if (!BN_add(W, W, r0))
284                    goto err;
285            }
286
287            /* more of step 8 */
288            if (!BN_mask_bits(W, bits - 1))
289                goto err;
290            if (!BN_copy(X, W))
291                goto err;
292            if (!BN_add(X, X, test))
293                goto err;
294
295            /* step 9 */
296            if (!BN_lshift1(r0, q))
297                goto err;
298            if (!BN_mod(c, X, r0, ctx))
299                goto err;
300            if (!BN_sub(r0, c, BN_value_one()))
301                goto err;
302            if (!BN_sub(p, X, r0))
303                goto err;
304
305            /* step 10 */
306            if (BN_cmp(p, test) >= 0) {
307                /* step 11 */
308                r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb);
309                if (r > 0)
310                    goto end;   /* found it */
311                if (r != 0)
312                    goto err;
313            }
314
315            /* step 13 */
316            counter++;
317            /* "offset = offset + n + 1" */
318
319            /* step 14 */
320            if (counter >= 4096)
321                break;
322        }
323    }
324 end:
325    if (!BN_GENCB_call(cb, 2, 1))
326        goto err;
327
328    /* We now need to generate g */
329    /* Set r0=(p-1)/q */
330    if (!BN_sub(test, p, BN_value_one()))
331        goto err;
332    if (!BN_div(r0, NULL, test, q, ctx))
333        goto err;
334
335    if (!BN_set_word(test, h))
336        goto err;
337    if (!BN_MONT_CTX_set(mont, p, ctx))
338        goto err;
339
340    for (;;) {
341        /* g=test^r0%p */
342        if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont))
343            goto err;
344        if (!BN_is_one(g))
345            break;
346        if (!BN_add(test, test, BN_value_one()))
347            goto err;
348        h++;
349    }
350
351    if (!BN_GENCB_call(cb, 3, 1))
352        goto err;
353
354    ok = 1;
355 err:
356    if (ok) {
357        if (ret->p)
358            BN_free(ret->p);
359        if (ret->q)
360            BN_free(ret->q);
361        if (ret->g)
362            BN_free(ret->g);
363        ret->p = BN_dup(p);
364        ret->q = BN_dup(q);
365        ret->g = BN_dup(g);
366        if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
367            ok = 0;
368            goto err;
369        }
370        if (counter_ret != NULL)
371            *counter_ret = counter;
372        if (h_ret != NULL)
373            *h_ret = h;
374        if (seed_out)
375            memcpy(seed_out, seed, qsize);
376    }
377    if (ctx) {
378        BN_CTX_end(ctx);
379        BN_CTX_free(ctx);
380    }
381    if (mont != NULL)
382        BN_MONT_CTX_free(mont);
383    return ok;
384}
385#endif
386