1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
2 * All rights reserved.
3 *
4 * This package is an SSL implementation written
5 * by Eric Young (eay@cryptsoft.com).
6 * The implementation was written so as to conform with Netscapes SSL.
7 *
8 * This library is free for commercial and non-commercial use as long as
9 * the following conditions are aheared to. The following conditions
10 * apply to all code found in this distribution, be it the RC4, RSA,
11 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
12 * included with this distribution is covered by the same copyright terms
13 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
14 *
15 * Copyright remains Eric Young's, and as such any Copyright notices in
16 * the code are not to be removed.
17 * If this package is used in a product, Eric Young should be given attribution
18 * as the author of the parts of the library used.
19 * This can be in the form of a textual message at program startup or
20 * in documentation (online or textual) provided with the package.
21 *
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that the following conditions
24 * are met:
25 * 1. Redistributions of source code must retain the copyright
26 * notice, this list of conditions and the following disclaimer.
27 * 2. Redistributions in binary form must reproduce the above copyright
28 * notice, this list of conditions and the following disclaimer in the
29 * documentation and/or other materials provided with the distribution.
30 * 3. All advertising materials mentioning features or use of this software
31 * must display the following acknowledgement:
32 * "This product includes cryptographic software written by
33 * Eric Young (eay@cryptsoft.com)"
34 * The word 'cryptographic' can be left out if the rouines from the library
35 * being used are not cryptographic related :-).
36 * 4. If you include any Windows specific code (or a derivative thereof) from
37 * the apps directory (application code) you must include an acknowledgement:
38 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
39 *
40 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50 * SUCH DAMAGE.
51 *
52 * The licence and distribution terms for any publically available version or
53 * derivative of this code cannot be changed. i.e. this code cannot simply be
54 * copied and put under another distribution licence
55 * [including the GNU Public Licence.]
56 *
57 * The DSS routines are based on patches supplied by
58 * Steven Schoch <schoch@sheba.arc.nasa.gov>. */
59
60 #include <openssl/dsa.h>
61
62 #include <string.h>
63
64 #include <openssl/bn.h>
65 #include <openssl/dh.h>
66 #include <openssl/digest.h>
67 #include <openssl/engine.h>
68 #include <openssl/err.h>
69 #include <openssl/ex_data.h>
70 #include <openssl/mem.h>
71 #include <openssl/rand.h>
72 #include <openssl/sha.h>
73 #include <openssl/thread.h>
74
75 #include "../fipsmodule/bn/internal.h"
76 #include "../internal.h"
77
78
79 #define OPENSSL_DSA_MAX_MODULUS_BITS 10000
80
81 /* Primality test according to FIPS PUB 186[-1], Appendix 2.1: 50 rounds of
82 * Rabin-Miller */
83 #define DSS_prime_checks 50
84
85 static CRYPTO_EX_DATA_CLASS g_ex_data_class = CRYPTO_EX_DATA_CLASS_INIT;
86
DSA_new(void)87 DSA *DSA_new(void) {
88 DSA *dsa = OPENSSL_malloc(sizeof(DSA));
89 if (dsa == NULL) {
90 OPENSSL_PUT_ERROR(DSA, ERR_R_MALLOC_FAILURE);
91 return NULL;
92 }
93
94 OPENSSL_memset(dsa, 0, sizeof(DSA));
95
96 dsa->references = 1;
97
98 CRYPTO_MUTEX_init(&dsa->method_mont_lock);
99 CRYPTO_new_ex_data(&dsa->ex_data);
100
101 return dsa;
102 }
103
DSA_free(DSA * dsa)104 void DSA_free(DSA *dsa) {
105 if (dsa == NULL) {
106 return;
107 }
108
109 if (!CRYPTO_refcount_dec_and_test_zero(&dsa->references)) {
110 return;
111 }
112
113 CRYPTO_free_ex_data(&g_ex_data_class, dsa, &dsa->ex_data);
114
115 BN_clear_free(dsa->p);
116 BN_clear_free(dsa->q);
117 BN_clear_free(dsa->g);
118 BN_clear_free(dsa->pub_key);
119 BN_clear_free(dsa->priv_key);
120 BN_clear_free(dsa->kinv);
121 BN_clear_free(dsa->r);
122 BN_MONT_CTX_free(dsa->method_mont_p);
123 BN_MONT_CTX_free(dsa->method_mont_q);
124 CRYPTO_MUTEX_cleanup(&dsa->method_mont_lock);
125 OPENSSL_free(dsa);
126 }
127
DSA_up_ref(DSA * dsa)128 int DSA_up_ref(DSA *dsa) {
129 CRYPTO_refcount_inc(&dsa->references);
130 return 1;
131 }
132
DSA_get0_key(const DSA * dsa,const BIGNUM ** out_pub_key,const BIGNUM ** out_priv_key)133 void DSA_get0_key(const DSA *dsa, const BIGNUM **out_pub_key,
134 const BIGNUM **out_priv_key) {
135 if (out_pub_key != NULL) {
136 *out_pub_key = dsa->pub_key;
137 }
138 if (out_priv_key != NULL) {
139 *out_priv_key = dsa->priv_key;
140 }
141 }
142
DSA_get0_pqg(const DSA * dsa,const BIGNUM ** out_p,const BIGNUM ** out_q,const BIGNUM ** out_g)143 void DSA_get0_pqg(const DSA *dsa, const BIGNUM **out_p, const BIGNUM **out_q,
144 const BIGNUM **out_g) {
145 if (out_p != NULL) {
146 *out_p = dsa->p;
147 }
148 if (out_q != NULL) {
149 *out_q = dsa->q;
150 }
151 if (out_g != NULL) {
152 *out_g = dsa->g;
153 }
154 }
155
DSA_generate_parameters_ex(DSA * dsa,unsigned bits,const uint8_t * seed_in,size_t seed_len,int * out_counter,unsigned long * out_h,BN_GENCB * cb)156 int DSA_generate_parameters_ex(DSA *dsa, unsigned bits, const uint8_t *seed_in,
157 size_t seed_len, int *out_counter,
158 unsigned long *out_h, BN_GENCB *cb) {
159 int ok = 0;
160 unsigned char seed[SHA256_DIGEST_LENGTH];
161 unsigned char md[SHA256_DIGEST_LENGTH];
162 unsigned char buf[SHA256_DIGEST_LENGTH], buf2[SHA256_DIGEST_LENGTH];
163 BIGNUM *r0, *W, *X, *c, *test;
164 BIGNUM *g = NULL, *q = NULL, *p = NULL;
165 BN_MONT_CTX *mont = NULL;
166 int k, n = 0, m = 0;
167 unsigned i;
168 int counter = 0;
169 int r = 0;
170 BN_CTX *ctx = NULL;
171 unsigned int h = 2;
172 unsigned qsize;
173 const EVP_MD *evpmd;
174
175 evpmd = (bits >= 2048) ? EVP_sha256() : EVP_sha1();
176 qsize = EVP_MD_size(evpmd);
177
178 if (bits < 512) {
179 bits = 512;
180 }
181
182 bits = (bits + 63) / 64 * 64;
183
184 if (seed_in != NULL) {
185 if (seed_len < (size_t)qsize) {
186 return 0;
187 }
188 if (seed_len > (size_t)qsize) {
189 /* Only consume as much seed as is expected. */
190 seed_len = qsize;
191 }
192 OPENSSL_memcpy(seed, seed_in, seed_len);
193 }
194
195 ctx = BN_CTX_new();
196 if (ctx == NULL) {
197 goto err;
198 }
199 BN_CTX_start(ctx);
200
201 mont = BN_MONT_CTX_new();
202 if (mont == NULL) {
203 goto err;
204 }
205
206 r0 = BN_CTX_get(ctx);
207 g = BN_CTX_get(ctx);
208 W = BN_CTX_get(ctx);
209 q = BN_CTX_get(ctx);
210 X = BN_CTX_get(ctx);
211 c = BN_CTX_get(ctx);
212 p = BN_CTX_get(ctx);
213 test = BN_CTX_get(ctx);
214
215 if (test == NULL || !BN_lshift(test, BN_value_one(), bits - 1)) {
216 goto err;
217 }
218
219 for (;;) {
220 /* Find q. */
221 for (;;) {
222 /* step 1 */
223 if (!BN_GENCB_call(cb, 0, m++)) {
224 goto err;
225 }
226
227 int use_random_seed = (seed_in == NULL);
228 if (use_random_seed) {
229 if (!RAND_bytes(seed, qsize)) {
230 goto err;
231 }
232 } else {
233 /* If we come back through, use random seed next time. */
234 seed_in = NULL;
235 }
236 OPENSSL_memcpy(buf, seed, qsize);
237 OPENSSL_memcpy(buf2, seed, qsize);
238 /* precompute "SEED + 1" for step 7: */
239 for (i = qsize - 1; i < qsize; i--) {
240 buf[i]++;
241 if (buf[i] != 0) {
242 break;
243 }
244 }
245
246 /* step 2 */
247 if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL) ||
248 !EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL)) {
249 goto err;
250 }
251 for (i = 0; i < qsize; i++) {
252 md[i] ^= buf2[i];
253 }
254
255 /* step 3 */
256 md[0] |= 0x80;
257 md[qsize - 1] |= 0x01;
258 if (!BN_bin2bn(md, qsize, q)) {
259 goto err;
260 }
261
262 /* step 4 */
263 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx, use_random_seed, cb);
264 if (r > 0) {
265 break;
266 }
267 if (r != 0) {
268 goto err;
269 }
270
271 /* do a callback call */
272 /* step 5 */
273 }
274
275 if (!BN_GENCB_call(cb, 2, 0) || !BN_GENCB_call(cb, 3, 0)) {
276 goto err;
277 }
278
279 /* step 6 */
280 counter = 0;
281 /* "offset = 2" */
282
283 n = (bits - 1) / 160;
284
285 for (;;) {
286 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter)) {
287 goto err;
288 }
289
290 /* step 7 */
291 BN_zero(W);
292 /* now 'buf' contains "SEED + offset - 1" */
293 for (k = 0; k <= n; k++) {
294 /* obtain "SEED + offset + k" by incrementing: */
295 for (i = qsize - 1; i < qsize; i--) {
296 buf[i]++;
297 if (buf[i] != 0) {
298 break;
299 }
300 }
301
302 if (!EVP_Digest(buf, qsize, md, NULL, evpmd, NULL)) {
303 goto err;
304 }
305
306 /* step 8 */
307 if (!BN_bin2bn(md, qsize, r0) ||
308 !BN_lshift(r0, r0, (qsize << 3) * k) ||
309 !BN_add(W, W, r0)) {
310 goto err;
311 }
312 }
313
314 /* more of step 8 */
315 if (!BN_mask_bits(W, bits - 1) ||
316 !BN_copy(X, W) ||
317 !BN_add(X, X, test)) {
318 goto err;
319 }
320
321 /* step 9 */
322 if (!BN_lshift1(r0, q) ||
323 !BN_mod(c, X, r0, ctx) ||
324 !BN_sub(r0, c, BN_value_one()) ||
325 !BN_sub(p, X, r0)) {
326 goto err;
327 }
328
329 /* step 10 */
330 if (BN_cmp(p, test) >= 0) {
331 /* step 11 */
332 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb);
333 if (r > 0) {
334 goto end; /* found it */
335 }
336 if (r != 0) {
337 goto err;
338 }
339 }
340
341 /* step 13 */
342 counter++;
343 /* "offset = offset + n + 1" */
344
345 /* step 14 */
346 if (counter >= 4096) {
347 break;
348 }
349 }
350 }
351 end:
352 if (!BN_GENCB_call(cb, 2, 1)) {
353 goto err;
354 }
355
356 /* We now need to generate g */
357 /* Set r0=(p-1)/q */
358 if (!BN_sub(test, p, BN_value_one()) ||
359 !BN_div(r0, NULL, test, q, ctx)) {
360 goto err;
361 }
362
363 if (!BN_set_word(test, h) ||
364 !BN_MONT_CTX_set(mont, p, ctx)) {
365 goto err;
366 }
367
368 for (;;) {
369 /* g=test^r0%p */
370 if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont)) {
371 goto err;
372 }
373 if (!BN_is_one(g)) {
374 break;
375 }
376 if (!BN_add(test, test, BN_value_one())) {
377 goto err;
378 }
379 h++;
380 }
381
382 if (!BN_GENCB_call(cb, 3, 1)) {
383 goto err;
384 }
385
386 ok = 1;
387
388 err:
389 if (ok) {
390 BN_free(dsa->p);
391 BN_free(dsa->q);
392 BN_free(dsa->g);
393 dsa->p = BN_dup(p);
394 dsa->q = BN_dup(q);
395 dsa->g = BN_dup(g);
396 if (dsa->p == NULL || dsa->q == NULL || dsa->g == NULL) {
397 ok = 0;
398 goto err;
399 }
400 if (out_counter != NULL) {
401 *out_counter = counter;
402 }
403 if (out_h != NULL) {
404 *out_h = h;
405 }
406 }
407
408 if (ctx) {
409 BN_CTX_end(ctx);
410 BN_CTX_free(ctx);
411 }
412
413 BN_MONT_CTX_free(mont);
414
415 return ok;
416 }
417
DSAparams_dup(const DSA * dsa)418 DSA *DSAparams_dup(const DSA *dsa) {
419 DSA *ret = DSA_new();
420 if (ret == NULL) {
421 return NULL;
422 }
423 ret->p = BN_dup(dsa->p);
424 ret->q = BN_dup(dsa->q);
425 ret->g = BN_dup(dsa->g);
426 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
427 DSA_free(ret);
428 return NULL;
429 }
430 return ret;
431 }
432
DSA_generate_key(DSA * dsa)433 int DSA_generate_key(DSA *dsa) {
434 int ok = 0;
435 BN_CTX *ctx = NULL;
436 BIGNUM *pub_key = NULL, *priv_key = NULL;
437
438 ctx = BN_CTX_new();
439 if (ctx == NULL) {
440 goto err;
441 }
442
443 priv_key = dsa->priv_key;
444 if (priv_key == NULL) {
445 priv_key = BN_new();
446 if (priv_key == NULL) {
447 goto err;
448 }
449 }
450
451 if (!BN_rand_range_ex(priv_key, 1, dsa->q)) {
452 goto err;
453 }
454
455 pub_key = dsa->pub_key;
456 if (pub_key == NULL) {
457 pub_key = BN_new();
458 if (pub_key == NULL) {
459 goto err;
460 }
461 }
462
463 if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p, &dsa->method_mont_lock,
464 dsa->p, ctx) ||
465 !BN_mod_exp_mont_consttime(pub_key, dsa->g, priv_key, dsa->p, ctx,
466 dsa->method_mont_p)) {
467 goto err;
468 }
469
470 dsa->priv_key = priv_key;
471 dsa->pub_key = pub_key;
472 ok = 1;
473
474 err:
475 if (dsa->pub_key == NULL) {
476 BN_free(pub_key);
477 }
478 if (dsa->priv_key == NULL) {
479 BN_free(priv_key);
480 }
481 BN_CTX_free(ctx);
482
483 return ok;
484 }
485
DSA_SIG_new(void)486 DSA_SIG *DSA_SIG_new(void) {
487 DSA_SIG *sig;
488 sig = OPENSSL_malloc(sizeof(DSA_SIG));
489 if (!sig) {
490 return NULL;
491 }
492 sig->r = NULL;
493 sig->s = NULL;
494 return sig;
495 }
496
DSA_SIG_free(DSA_SIG * sig)497 void DSA_SIG_free(DSA_SIG *sig) {
498 if (!sig) {
499 return;
500 }
501
502 BN_free(sig->r);
503 BN_free(sig->s);
504 OPENSSL_free(sig);
505 }
506
DSA_do_sign(const uint8_t * digest,size_t digest_len,DSA * dsa)507 DSA_SIG *DSA_do_sign(const uint8_t *digest, size_t digest_len, DSA *dsa) {
508 BIGNUM *kinv = NULL, *r = NULL, *s = NULL;
509 BIGNUM m;
510 BIGNUM xr;
511 BN_CTX *ctx = NULL;
512 int reason = ERR_R_BN_LIB;
513 DSA_SIG *ret = NULL;
514 int noredo = 0;
515
516 BN_init(&m);
517 BN_init(&xr);
518
519 if (!dsa->p || !dsa->q || !dsa->g) {
520 reason = DSA_R_MISSING_PARAMETERS;
521 goto err;
522 }
523
524 s = BN_new();
525 if (s == NULL) {
526 goto err;
527 }
528 ctx = BN_CTX_new();
529 if (ctx == NULL) {
530 goto err;
531 }
532
533 redo:
534 if (dsa->kinv == NULL || dsa->r == NULL) {
535 if (!DSA_sign_setup(dsa, ctx, &kinv, &r)) {
536 goto err;
537 }
538 } else {
539 kinv = dsa->kinv;
540 dsa->kinv = NULL;
541 r = dsa->r;
542 dsa->r = NULL;
543 noredo = 1;
544 }
545
546 if (digest_len > BN_num_bytes(dsa->q)) {
547 /* if the digest length is greater than the size of q use the
548 * BN_num_bits(dsa->q) leftmost bits of the digest, see
549 * fips 186-3, 4.2 */
550 digest_len = BN_num_bytes(dsa->q);
551 }
552
553 if (BN_bin2bn(digest, digest_len, &m) == NULL) {
554 goto err;
555 }
556
557 /* Compute s = inv(k) (m + xr) mod q */
558 if (!BN_mod_mul(&xr, dsa->priv_key, r, dsa->q, ctx)) {
559 goto err; /* s = xr */
560 }
561 if (!BN_add(s, &xr, &m)) {
562 goto err; /* s = m + xr */
563 }
564 if (BN_cmp(s, dsa->q) > 0) {
565 if (!BN_sub(s, s, dsa->q)) {
566 goto err;
567 }
568 }
569 if (!BN_mod_mul(s, s, kinv, dsa->q, ctx)) {
570 goto err;
571 }
572
573 /* Redo if r or s is zero as required by FIPS 186-3: this is
574 * very unlikely. */
575 if (BN_is_zero(r) || BN_is_zero(s)) {
576 if (noredo) {
577 reason = DSA_R_NEED_NEW_SETUP_VALUES;
578 goto err;
579 }
580 goto redo;
581 }
582 ret = DSA_SIG_new();
583 if (ret == NULL) {
584 goto err;
585 }
586 ret->r = r;
587 ret->s = s;
588
589 err:
590 if (ret == NULL) {
591 OPENSSL_PUT_ERROR(DSA, reason);
592 BN_free(r);
593 BN_free(s);
594 }
595 BN_CTX_free(ctx);
596 BN_clear_free(&m);
597 BN_clear_free(&xr);
598 BN_clear_free(kinv);
599
600 return ret;
601 }
602
DSA_do_verify(const uint8_t * digest,size_t digest_len,DSA_SIG * sig,const DSA * dsa)603 int DSA_do_verify(const uint8_t *digest, size_t digest_len, DSA_SIG *sig,
604 const DSA *dsa) {
605 int valid;
606 if (!DSA_do_check_signature(&valid, digest, digest_len, sig, dsa)) {
607 return -1;
608 }
609 return valid;
610 }
611
DSA_do_check_signature(int * out_valid,const uint8_t * digest,size_t digest_len,DSA_SIG * sig,const DSA * dsa)612 int DSA_do_check_signature(int *out_valid, const uint8_t *digest,
613 size_t digest_len, DSA_SIG *sig, const DSA *dsa) {
614 BN_CTX *ctx;
615 BIGNUM u1, u2, t1;
616 int ret = 0;
617 unsigned i;
618
619 *out_valid = 0;
620
621 if (!dsa->p || !dsa->q || !dsa->g) {
622 OPENSSL_PUT_ERROR(DSA, DSA_R_MISSING_PARAMETERS);
623 return 0;
624 }
625
626 i = BN_num_bits(dsa->q);
627 /* fips 186-3 allows only different sizes for q */
628 if (i != 160 && i != 224 && i != 256) {
629 OPENSSL_PUT_ERROR(DSA, DSA_R_BAD_Q_VALUE);
630 return 0;
631 }
632
633 if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) {
634 OPENSSL_PUT_ERROR(DSA, DSA_R_MODULUS_TOO_LARGE);
635 return 0;
636 }
637
638 BN_init(&u1);
639 BN_init(&u2);
640 BN_init(&t1);
641
642 ctx = BN_CTX_new();
643 if (ctx == NULL) {
644 goto err;
645 }
646
647 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
648 BN_ucmp(sig->r, dsa->q) >= 0) {
649 ret = 1;
650 goto err;
651 }
652 if (BN_is_zero(sig->s) || BN_is_negative(sig->s) ||
653 BN_ucmp(sig->s, dsa->q) >= 0) {
654 ret = 1;
655 goto err;
656 }
657
658 /* Calculate W = inv(S) mod Q
659 * save W in u2 */
660 if (BN_mod_inverse(&u2, sig->s, dsa->q, ctx) == NULL) {
661 goto err;
662 }
663
664 /* save M in u1 */
665 if (digest_len > (i >> 3)) {
666 /* if the digest length is greater than the size of q use the
667 * BN_num_bits(dsa->q) leftmost bits of the digest, see
668 * fips 186-3, 4.2 */
669 digest_len = (i >> 3);
670 }
671
672 if (BN_bin2bn(digest, digest_len, &u1) == NULL) {
673 goto err;
674 }
675
676 /* u1 = M * w mod q */
677 if (!BN_mod_mul(&u1, &u1, &u2, dsa->q, ctx)) {
678 goto err;
679 }
680
681 /* u2 = r * w mod q */
682 if (!BN_mod_mul(&u2, sig->r, &u2, dsa->q, ctx)) {
683 goto err;
684 }
685
686 if (!BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dsa->method_mont_p,
687 (CRYPTO_MUTEX *)&dsa->method_mont_lock, dsa->p,
688 ctx)) {
689 goto err;
690 }
691
692 if (!BN_mod_exp2_mont(&t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p, ctx,
693 dsa->method_mont_p)) {
694 goto err;
695 }
696
697 /* BN_copy(&u1,&t1); */
698 /* let u1 = u1 mod q */
699 if (!BN_mod(&u1, &t1, dsa->q, ctx)) {
700 goto err;
701 }
702
703 /* V is now in u1. If the signature is correct, it will be
704 * equal to R. */
705 *out_valid = BN_ucmp(&u1, sig->r) == 0;
706 ret = 1;
707
708 err:
709 if (ret != 1) {
710 OPENSSL_PUT_ERROR(DSA, ERR_R_BN_LIB);
711 }
712 BN_CTX_free(ctx);
713 BN_free(&u1);
714 BN_free(&u2);
715 BN_free(&t1);
716
717 return ret;
718 }
719
DSA_sign(int type,const uint8_t * digest,size_t digest_len,uint8_t * out_sig,unsigned int * out_siglen,DSA * dsa)720 int DSA_sign(int type, const uint8_t *digest, size_t digest_len,
721 uint8_t *out_sig, unsigned int *out_siglen, DSA *dsa) {
722 DSA_SIG *s;
723
724 s = DSA_do_sign(digest, digest_len, dsa);
725 if (s == NULL) {
726 *out_siglen = 0;
727 return 0;
728 }
729
730 *out_siglen = i2d_DSA_SIG(s, &out_sig);
731 DSA_SIG_free(s);
732 return 1;
733 }
734
DSA_verify(int type,const uint8_t * digest,size_t digest_len,const uint8_t * sig,size_t sig_len,const DSA * dsa)735 int DSA_verify(int type, const uint8_t *digest, size_t digest_len,
736 const uint8_t *sig, size_t sig_len, const DSA *dsa) {
737 int valid;
738 if (!DSA_check_signature(&valid, digest, digest_len, sig, sig_len, dsa)) {
739 return -1;
740 }
741 return valid;
742 }
743
DSA_check_signature(int * out_valid,const uint8_t * digest,size_t digest_len,const uint8_t * sig,size_t sig_len,const DSA * dsa)744 int DSA_check_signature(int *out_valid, const uint8_t *digest,
745 size_t digest_len, const uint8_t *sig, size_t sig_len,
746 const DSA *dsa) {
747 DSA_SIG *s = NULL;
748 int ret = 0;
749 uint8_t *der = NULL;
750
751 s = DSA_SIG_new();
752 if (s == NULL) {
753 goto err;
754 }
755
756 const uint8_t *sigp = sig;
757 if (d2i_DSA_SIG(&s, &sigp, sig_len) == NULL || sigp != sig + sig_len) {
758 goto err;
759 }
760
761 /* Ensure that the signature uses DER and doesn't have trailing garbage. */
762 int der_len = i2d_DSA_SIG(s, &der);
763 if (der_len < 0 || (size_t)der_len != sig_len ||
764 OPENSSL_memcmp(sig, der, sig_len)) {
765 goto err;
766 }
767
768 ret = DSA_do_check_signature(out_valid, digest, digest_len, s, dsa);
769
770 err:
771 OPENSSL_free(der);
772 DSA_SIG_free(s);
773 return ret;
774 }
775
776 /* der_len_len returns the number of bytes needed to represent a length of |len|
777 * in DER. */
der_len_len(size_t len)778 static size_t der_len_len(size_t len) {
779 if (len < 0x80) {
780 return 1;
781 }
782 size_t ret = 1;
783 while (len > 0) {
784 ret++;
785 len >>= 8;
786 }
787 return ret;
788 }
789
DSA_size(const DSA * dsa)790 int DSA_size(const DSA *dsa) {
791 size_t order_len = BN_num_bytes(dsa->q);
792 /* Compute the maximum length of an |order_len| byte integer. Defensively
793 * assume that the leading 0x00 is included. */
794 size_t integer_len = 1 /* tag */ + der_len_len(order_len + 1) + 1 + order_len;
795 if (integer_len < order_len) {
796 return 0;
797 }
798 /* A DSA signature is two INTEGERs. */
799 size_t value_len = 2 * integer_len;
800 if (value_len < integer_len) {
801 return 0;
802 }
803 /* Add the header. */
804 size_t ret = 1 /* tag */ + der_len_len(value_len) + value_len;
805 if (ret < value_len) {
806 return 0;
807 }
808 return ret;
809 }
810
DSA_sign_setup(const DSA * dsa,BN_CTX * ctx_in,BIGNUM ** out_kinv,BIGNUM ** out_r)811 int DSA_sign_setup(const DSA *dsa, BN_CTX *ctx_in, BIGNUM **out_kinv,
812 BIGNUM **out_r) {
813 BN_CTX *ctx;
814 BIGNUM k, kq, *kinv = NULL, *r = NULL;
815 int ret = 0;
816
817 if (!dsa->p || !dsa->q || !dsa->g) {
818 OPENSSL_PUT_ERROR(DSA, DSA_R_MISSING_PARAMETERS);
819 return 0;
820 }
821
822 BN_init(&k);
823 BN_init(&kq);
824
825 ctx = ctx_in;
826 if (ctx == NULL) {
827 ctx = BN_CTX_new();
828 if (ctx == NULL) {
829 goto err;
830 }
831 }
832
833 r = BN_new();
834 if (r == NULL) {
835 goto err;
836 }
837
838 /* Get random k */
839 if (!BN_rand_range_ex(&k, 1, dsa->q)) {
840 goto err;
841 }
842
843 if (!BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dsa->method_mont_p,
844 (CRYPTO_MUTEX *)&dsa->method_mont_lock, dsa->p,
845 ctx) ||
846 !BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dsa->method_mont_q,
847 (CRYPTO_MUTEX *)&dsa->method_mont_lock, dsa->q,
848 ctx)) {
849 goto err;
850 }
851
852 /* Compute r = (g^k mod p) mod q */
853 if (!BN_copy(&kq, &k)) {
854 goto err;
855 }
856
857 /* We do not want timing information to leak the length of k,
858 * so we compute g^k using an equivalent exponent of fixed length.
859 *
860 * (This is a kludge that we need because the BN_mod_exp_mont()
861 * does not let us specify the desired timing behaviour.) */
862
863 if (!BN_add(&kq, &kq, dsa->q)) {
864 goto err;
865 }
866 if (BN_num_bits(&kq) <= BN_num_bits(dsa->q) && !BN_add(&kq, &kq, dsa->q)) {
867 goto err;
868 }
869
870 if (!BN_mod_exp_mont_consttime(r, dsa->g, &kq, dsa->p, ctx,
871 dsa->method_mont_p)) {
872 goto err;
873 }
874 if (!BN_mod(r, r, dsa->q, ctx)) {
875 goto err;
876 }
877
878 /* Compute part of 's = inv(k) (m + xr) mod q' using Fermat's Little
879 * Theorem. */
880 kinv = BN_new();
881 if (kinv == NULL ||
882 !bn_mod_inverse_prime(kinv, &k, dsa->q, ctx, dsa->method_mont_q)) {
883 goto err;
884 }
885
886 BN_clear_free(*out_kinv);
887 *out_kinv = kinv;
888 kinv = NULL;
889 BN_clear_free(*out_r);
890 *out_r = r;
891 ret = 1;
892
893 err:
894 if (!ret) {
895 OPENSSL_PUT_ERROR(DSA, ERR_R_BN_LIB);
896 if (r != NULL) {
897 BN_clear_free(r);
898 }
899 }
900
901 if (ctx_in == NULL) {
902 BN_CTX_free(ctx);
903 }
904 BN_clear_free(&k);
905 BN_clear_free(&kq);
906 BN_clear_free(kinv);
907 return ret;
908 }
909
DSA_get_ex_new_index(long argl,void * argp,CRYPTO_EX_unused * unused,CRYPTO_EX_dup * dup_unused,CRYPTO_EX_free * free_func)910 int DSA_get_ex_new_index(long argl, void *argp, CRYPTO_EX_unused *unused,
911 CRYPTO_EX_dup *dup_unused, CRYPTO_EX_free *free_func) {
912 int index;
913 if (!CRYPTO_get_ex_new_index(&g_ex_data_class, &index, argl, argp,
914 free_func)) {
915 return -1;
916 }
917 return index;
918 }
919
DSA_set_ex_data(DSA * d,int idx,void * arg)920 int DSA_set_ex_data(DSA *d, int idx, void *arg) {
921 return CRYPTO_set_ex_data(&d->ex_data, idx, arg);
922 }
923
DSA_get_ex_data(const DSA * d,int idx)924 void *DSA_get_ex_data(const DSA *d, int idx) {
925 return CRYPTO_get_ex_data(&d->ex_data, idx);
926 }
927
DSA_dup_DH(const DSA * r)928 DH *DSA_dup_DH(const DSA *r) {
929 DH *ret = NULL;
930
931 if (r == NULL) {
932 goto err;
933 }
934 ret = DH_new();
935 if (ret == NULL) {
936 goto err;
937 }
938 if (r->q != NULL) {
939 ret->priv_length = BN_num_bits(r->q);
940 if ((ret->q = BN_dup(r->q)) == NULL) {
941 goto err;
942 }
943 }
944 if ((r->p != NULL && (ret->p = BN_dup(r->p)) == NULL) ||
945 (r->g != NULL && (ret->g = BN_dup(r->g)) == NULL) ||
946 (r->pub_key != NULL && (ret->pub_key = BN_dup(r->pub_key)) == NULL) ||
947 (r->priv_key != NULL && (ret->priv_key = BN_dup(r->priv_key)) == NULL)) {
948 goto err;
949 }
950
951 return ret;
952
953 err:
954 DH_free(ret);
955 return NULL;
956 }
957