1/*
2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10/*
11 * Parameter generation follows the updated Appendix 2.2 for FIPS PUB 186,
12 * also Appendix 2.2 of FIPS PUB 186-1 (i.e. use SHA as defined in FIPS PUB
13 * 180-1)
14 */
15#define xxxHASH EVP_sha1()
16
17#include <openssl/opensslconf.h>
18#include <stdio.h>
19#include "internal/cryptlib.h"
20#include <openssl/evp.h>
21#include <openssl/bn.h>
22#include <openssl/rand.h>
23#include <openssl/sha.h>
24#include "dsa_local.h"
25
26int DSA_generate_parameters_ex(DSA *ret, int bits,
27 const unsigned char *seed_in, int seed_len,
28 int *counter_ret, unsigned long *h_ret,
29 BN_GENCB *cb)
30{
31 if (ret->meth->dsa_paramgen)
32 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
33 counter_ret, h_ret, cb);
34 else {
35 const EVP_MD *evpmd = bits >= 2048 ? EVP_sha256() : EVP_sha1();
36 size_t qbits = EVP_MD_size(evpmd) * 8;
37
38 return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
39 seed_in, seed_len, NULL, counter_ret,
40 h_ret, cb);
41 }
42}
43
44int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
45 const EVP_MD *evpmd, const unsigned char *seed_in,
46 size_t seed_len, unsigned char *seed_out,
47 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
48{
49 int ok = 0;
50 unsigned char seed[SHA256_DIGEST_LENGTH];
51 unsigned char md[SHA256_DIGEST_LENGTH];
52 unsigned char buf[SHA256_DIGEST_LENGTH], buf2[SHA256_DIGEST_LENGTH];
53 BIGNUM *r0, *W, *X, *c, *test;
54 BIGNUM *g = NULL, *q = NULL, *p = NULL;
55 BN_MONT_CTX *mont = NULL;
56 int i, k, n = 0, m = 0, qsize = qbits >> 3;
57 int counter = 0;
58 int r = 0;
59 BN_CTX *ctx = NULL;
60 unsigned int h = 2;
61
62 if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
63 qsize != SHA256_DIGEST_LENGTH)
64 /* invalid q size */
65 return 0;
66
67 if (evpmd == NULL) {
68 if (qsize == SHA_DIGEST_LENGTH)
69 evpmd = EVP_sha1();
70 else if (qsize == SHA224_DIGEST_LENGTH)
71 evpmd = EVP_sha224();
72 else
73 evpmd = EVP_sha256();
74 } else {
75 qsize = EVP_MD_size(evpmd);
76 }
77
78 if (bits < 512)
79 bits = 512;
80
81 bits = (bits + 63) / 64 * 64;
82
83 if (seed_in != NULL) {
84 if (seed_len < (size_t)qsize) {
85 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN, DSA_R_SEED_LEN_SMALL);
86 return 0;
87 }
88 if (seed_len > (size_t)qsize) {
89 /* Only consume as much seed as is expected. */
90 seed_len = qsize;
91 }
92 memcpy(seed, seed_in, seed_len);
93 }
94
95 if ((mont = BN_MONT_CTX_new()) == NULL)
96 goto err;
97
98 if ((ctx = BN_CTX_new()) == NULL)
99 goto err;
100
101 BN_CTX_start(ctx);
102
103 r0 = BN_CTX_get(ctx);
104 g = BN_CTX_get(ctx);
105 W = BN_CTX_get(ctx);
106 q = BN_CTX_get(ctx);
107 X = BN_CTX_get(ctx);
108 c = BN_CTX_get(ctx);
109 p = BN_CTX_get(ctx);
110 test = BN_CTX_get(ctx);
111
112 if (test == NULL)
113 goto err;
114
115 if (!BN_lshift(test, BN_value_one(), bits - 1))
116 goto err;
117
118 for (;;) {
119 for (;;) { /* find q */
120 int use_random_seed = (seed_in == NULL);
121
122 /* step 1 */
123 if (!BN_GENCB_call(cb, 0, m++))
124 goto err;
125
126 if (use_random_seed) {
127 if (RAND_bytes(seed, qsize) <= 0)
128 goto err;
129 } else {
130 /* If we come back through, use random seed next time. */
131 seed_in = NULL;
132 }
133 memcpy(buf, seed, qsize);
134 memcpy(buf2, seed, qsize);
135 /* precompute "SEED + 1" for step 7: */
136 for (i = qsize - 1; i >= 0; i--) {
137 buf[i]++;
138 if (buf[i] != 0)
139 break;
140 }
141
142 /* step 2 */
143 if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL))
144 goto err;
145 if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL))
146 goto err;
147 for (i = 0; i < qsize; i++)
148 md[i] ^= buf2[i];
149
150 /* step 3 */
151 md[0] |= 0x80;
152 md[qsize - 1] |= 0x01;
153 if (!BN_bin2bn(md, qsize, q))
154 goto err;
155
156 /* step 4 */
157 r = BN_check_prime(q, ctx, cb);
158 if (r > 0)
159 break;
160 if (r != 0)
161 goto err;
162
163 /* do a callback call */
164 /* step 5 */
165 }
166
167 if (!BN_GENCB_call(cb, 2, 0))
168 goto err;
169 if (!BN_GENCB_call(cb, 3, 0))
170 goto err;
171
172 /* step 6 */
173 counter = 0;
174 /* "offset = 2" */
175
176 n = (bits - 1) / 160;
177
178 for (;;) {
179 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
180 goto err;
181
182 /* step 7 */
183 BN_zero(W);
184 /* now 'buf' contains "SEED + offset - 1" */
185 for (k = 0; k <= n; k++) {
186 /*
187 * obtain "SEED + offset + k" by incrementing:
188 */
189 for (i = qsize - 1; i >= 0; i--) {
190 buf[i]++;
191 if (buf[i] != 0)
192 break;
193 }
194
195 if (!EVP_Digest(buf, qsize, md, NULL, evpmd, NULL))
196 goto err;
197
198 /* step 8 */
199 if (!BN_bin2bn(md, qsize, r0))
200 goto err;
201 if (!BN_lshift(r0, r0, (qsize << 3) * k))
202 goto err;
203 if (!BN_add(W, W, r0))
204 goto err;
205 }
206
207 /* more of step 8 */
208 if (!BN_mask_bits(W, bits - 1))
209 goto err;
210 if (!BN_copy(X, W))
211 goto err;
212 if (!BN_add(X, X, test))
213 goto err;
214
215 /* step 9 */
216 if (!BN_lshift1(r0, q))
217 goto err;
218 if (!BN_mod(c, X, r0, ctx))
219 goto err;
220 if (!BN_sub(r0, c, BN_value_one()))
221 goto err;
222 if (!BN_sub(p, X, r0))
223 goto err;
224
225 /* step 10 */
226 if (BN_cmp(p, test) >= 0) {
227 /* step 11 */
228 r = BN_check_prime(p, ctx, cb);
229 if (r > 0)
230 goto end; /* found it */
231 if (r != 0)
232 goto err;
233 }
234
235 /* step 13 */
236 counter++;
237 /* "offset = offset + n + 1" */
238
239 /* step 14 */
240 if (counter >= 4096)
241 break;
242 }
243 }
244 end:
245 if (!BN_GENCB_call(cb, 2, 1))
246 goto err;
247
248 /* We now need to generate g */
249 /* Set r0=(p-1)/q */
250 if (!BN_sub(test, p, BN_value_one()))
251 goto err;
252 if (!BN_div(r0, NULL, test, q, ctx))
253 goto err;
254
255 if (!BN_set_word(test, h))
256 goto err;
257 if (!BN_MONT_CTX_set(mont, p, ctx))
258 goto err;
259
260 for (;;) {
261 /* g=test^r0%p */
262 if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont))
263 goto err;
264 if (!BN_is_one(g))
265 break;
266 if (!BN_add(test, test, BN_value_one()))
267 goto err;
268 h++;
269 }
270
271 if (!BN_GENCB_call(cb, 3, 1))
272 goto err;
273
274 ok = 1;
275 err:
276 if (ok) {
277 BN_free(ret->p);
278 BN_free(ret->q);
279 BN_free(ret->g);
280 ret->p = BN_dup(p);
281 ret->q = BN_dup(q);
282 ret->g = BN_dup(g);
283 ret->dirty_cnt++;
284 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
285 ok = 0;
286 goto err;
287 }
288 if (counter_ret != NULL)
289 *counter_ret = counter;
290 if (h_ret != NULL)
291 *h_ret = h;
292 if (seed_out)
293 memcpy(seed_out, seed, qsize);
294 }
295 BN_CTX_end(ctx);
296 BN_CTX_free(ctx);
297 BN_MONT_CTX_free(mont);
298 return ok;
299}
300
301/*
302 * This is a parameter generation algorithm for the DSA2 algorithm as
303 * described in FIPS 186-3.
304 */
305
306int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N,
307 const EVP_MD *evpmd, const unsigned char *seed_in,
308 size_t seed_len, int idx, unsigned char *seed_out,
309 int *counter_ret, unsigned long *h_ret,
310 BN_GENCB *cb)
311{
312 int ok = -1;
313 unsigned char *seed = NULL, *seed_tmp = NULL;
314 unsigned char md[EVP_MAX_MD_SIZE];
315 int mdsize;
316 BIGNUM *r0, *W, *X, *c, *test;
317 BIGNUM *g = NULL, *q = NULL, *p = NULL;
318 BN_MONT_CTX *mont = NULL;
319 int i, k, n = 0, m = 0, qsize = N >> 3;
320 int counter = 0;
321 int r = 0;
322 BN_CTX *ctx = NULL;
323 EVP_MD_CTX *mctx = EVP_MD_CTX_new();
324 unsigned int h = 2;
325
326 if (mctx == NULL)
327 goto err;
328
329 /* make sure L > N, otherwise we'll get trapped in an infinite loop */
330 if (L <= N) {
331 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_INVALID_PARAMETERS);
332 goto err;
333 }
334
335 if (evpmd == NULL) {
336 if (N == 160)
337 evpmd = EVP_sha1();
338 else if (N == 224)
339 evpmd = EVP_sha224();
340 else
341 evpmd = EVP_sha256();
342 }
343
344 mdsize = EVP_MD_size(evpmd);
345 /* If unverifiable g generation only don't need seed */
346 if (!ret->p || !ret->q || idx >= 0) {
347 if (seed_len == 0)
348 seed_len = mdsize;
349
350 seed = OPENSSL_malloc(seed_len);
351
352 if (seed_out)
353 seed_tmp = seed_out;
354 else
355 seed_tmp = OPENSSL_malloc(seed_len);
356
357 if (seed == NULL || seed_tmp == NULL)
358 goto err;
359
360 if (seed_in)
361 memcpy(seed, seed_in, seed_len);
362
363 }
364
365 if ((ctx = BN_CTX_new()) == NULL)
366 goto err;
367
368 if ((mont = BN_MONT_CTX_new()) == NULL)
369 goto err;
370
371 BN_CTX_start(ctx);
372 r0 = BN_CTX_get(ctx);
373 g = BN_CTX_get(ctx);
374 W = BN_CTX_get(ctx);
375 X = BN_CTX_get(ctx);
376 c = BN_CTX_get(ctx);
377 test = BN_CTX_get(ctx);
378 if (test == NULL)
379 goto err;
380
381 /* if p, q already supplied generate g only */
382 if (ret->p && ret->q) {
383 p = ret->p;
384 q = ret->q;
385 if (idx >= 0)
386 memcpy(seed_tmp, seed, seed_len);
387 goto g_only;
388 } else {
389 p = BN_CTX_get(ctx);
390 q = BN_CTX_get(ctx);
391 if (q == NULL)
392 goto err;
393 }
394
395 if (!BN_lshift(test, BN_value_one(), L - 1))
396 goto err;
397 for (;;) {
398 for (;;) { /* find q */
399 unsigned char *pmd;
400 /* step 1 */
401 if (!BN_GENCB_call(cb, 0, m++))
402 goto err;
403
404 if (!seed_in) {
405 if (RAND_bytes(seed, seed_len) <= 0)
406 goto err;
407 }
408 /* step 2 */
409 if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL))
410 goto err;
411 /* Take least significant bits of md */
412 if (mdsize > qsize)
413 pmd = md + mdsize - qsize;
414 else
415 pmd = md;
416
417 if (mdsize < qsize)
418 memset(md + mdsize, 0, qsize - mdsize);
419
420 /* step 3 */
421 pmd[0] |= 0x80;
422 pmd[qsize - 1] |= 0x01;
423 if (!BN_bin2bn(pmd, qsize, q))
424 goto err;
425
426 /* step 4 */
427 r = BN_check_prime(q, ctx, cb);
428 if (r > 0)
429 break;
430 if (r != 0)
431 goto err;
432 /* Provided seed didn't produce a prime: error */
433 if (seed_in) {
434 ok = 0;
435 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_Q_NOT_PRIME);
436 goto err;
437 }
438
439 /* do a callback call */
440 /* step 5 */
441 }
442 /* Copy seed to seed_out before we mess with it */
443 if (seed_out)
444 memcpy(seed_out, seed, seed_len);
445
446 if (!BN_GENCB_call(cb, 2, 0))
447 goto err;
448 if (!BN_GENCB_call(cb, 3, 0))
449 goto err;
450
451 /* step 6 */
452 counter = 0;
453 /* "offset = 1" */
454
455 n = (L - 1) / (mdsize << 3);
456
457 for (;;) {
458 if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
459 goto err;
460
461 /* step 7 */
462 BN_zero(W);
463 /* now 'buf' contains "SEED + offset - 1" */
464 for (k = 0; k <= n; k++) {
465 /*
466 * obtain "SEED + offset + k" by incrementing:
467 */
468 for (i = seed_len - 1; i >= 0; i--) {
469 seed[i]++;
470 if (seed[i] != 0)
471 break;
472 }
473
474 if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL))
475 goto err;
476
477 /* step 8 */
478 if (!BN_bin2bn(md, mdsize, r0))
479 goto err;
480 if (!BN_lshift(r0, r0, (mdsize << 3) * k))
481 goto err;
482 if (!BN_add(W, W, r0))
483 goto err;
484 }
485
486 /* more of step 8 */
487 if (!BN_mask_bits(W, L - 1))
488 goto err;
489 if (!BN_copy(X, W))
490 goto err;
491 if (!BN_add(X, X, test))
492 goto err;
493
494 /* step 9 */
495 if (!BN_lshift1(r0, q))
496 goto err;
497 if (!BN_mod(c, X, r0, ctx))
498 goto err;
499 if (!BN_sub(r0, c, BN_value_one()))
500 goto err;
501 if (!BN_sub(p, X, r0))
502 goto err;
503
504 /* step 10 */
505 if (BN_cmp(p, test) >= 0) {
506 /* step 11 */
507 r = BN_check_prime(p, ctx, cb);
508 if (r > 0)
509 goto end; /* found it */
510 if (r != 0)
511 goto err;
512 }
513
514 /* step 13 */
515 counter++;
516 /* "offset = offset + n + 1" */
517
518 /* step 14 */
519 if (counter >= (int)(4 * L))
520 break;
521 }
522 if (seed_in) {
523 ok = 0;
524 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_INVALID_PARAMETERS);
525 goto err;
526 }
527 }
528 end:
529 if (!BN_GENCB_call(cb, 2, 1))
530 goto err;
531
532 g_only:
533
534 /* We now need to generate g */
535 /* Set r0=(p-1)/q */
536 if (!BN_sub(test, p, BN_value_one()))
537 goto err;
538 if (!BN_div(r0, NULL, test, q, ctx))
539 goto err;
540
541 if (idx < 0) {
542 if (!BN_set_word(test, h))
543 goto err;
544 } else
545 h = 1;
546 if (!BN_MONT_CTX_set(mont, p, ctx))
547 goto err;
548
549 for (;;) {
550 static const unsigned char ggen[4] = { 0x67, 0x67, 0x65, 0x6e };
551 if (idx >= 0) {
552 md[0] = idx & 0xff;
553 md[1] = (h >> 8) & 0xff;
554 md[2] = h & 0xff;
555 if (!EVP_DigestInit_ex(mctx, evpmd, NULL))
556 goto err;
557 if (!EVP_DigestUpdate(mctx, seed_tmp, seed_len))
558 goto err;
559 if (!EVP_DigestUpdate(mctx, ggen, sizeof(ggen)))
560 goto err;
561 if (!EVP_DigestUpdate(mctx, md, 3))
562 goto err;
563 if (!EVP_DigestFinal_ex(mctx, md, NULL))
564 goto err;
565 if (!BN_bin2bn(md, mdsize, test))
566 goto err;
567 }
568 /* g=test^r0%p */
569 if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont))
570 goto err;
571 if (!BN_is_one(g))
572 break;
573 if (idx < 0 && !BN_add(test, test, BN_value_one()))
574 goto err;
575 h++;
576 if (idx >= 0 && h > 0xffff)
577 goto err;
578 }
579
580 if (!BN_GENCB_call(cb, 3, 1))
581 goto err;
582
583 ok = 1;
584 err:
585 if (ok == 1) {
586 if (p != ret->p) {
587 BN_free(ret->p);
588 ret->p = BN_dup(p);
589 }
590 if (q != ret->q) {
591 BN_free(ret->q);
592 ret->q = BN_dup(q);
593 }
594 BN_free(ret->g);
595 ret->g = BN_dup(g);
596 if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
597 ok = -1;
598 goto err;
599 }
600 ret->dirty_cnt++;
601 if (counter_ret != NULL)
602 *counter_ret = counter;
603 if (h_ret != NULL)
604 *h_ret = h;
605 }
606 OPENSSL_free(seed);
607 if (seed_out != seed_tmp)
608 OPENSSL_free(seed_tmp);
609 BN_CTX_end(ctx);
610 BN_CTX_free(ctx);
611 BN_MONT_CTX_free(mont);
612 EVP_MD_CTX_free(mctx);
613 return ok;
614}
615