1 /*
2 * Copyright 2019-2021 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 * For the prime check..
12 * FIPS 186-4 Section C.3 Table C.1
13 * Returns the minimum number of Miller Rabin iterations for a L,N pair
14 * (where L = len(p), N = len(q))
15 * L N Min
16 * 1024 160 40
17 * 2048 224 56
18 * 2048 256 56
19 * 3072 256 64
20 *
21 * BN_check_prime() uses:
22 * 64 iterations for L <= 2048 OR
23 * 128 iterations for L > 2048
24 * So this satisfies the requirement.
25 */
26
27 #include <string.h> /* memset */
28 #include <openssl/sha.h> /* SHA_DIGEST_LENGTH */
29 #include <openssl/rand.h>
30 #include <openssl/err.h>
31 #include <openssl/dherr.h>
32 #include <openssl/dsaerr.h>
33 #include "crypto/bn.h"
34 #include "internal/ffc.h"
35
36 /*
37 * Verify that the passed in L, N pair for DH or DSA is valid.
38 * Returns 0 if invalid, otherwise it returns the security strength.
39 */
40
41 #ifdef FIPS_MODULE
ffc_validate_LN(size_t L,size_t N,int type,int verify)42 static int ffc_validate_LN(size_t L, size_t N, int type, int verify)
43 {
44 if (type == FFC_PARAM_TYPE_DH) {
45 /* Valid DH L,N parameters from SP800-56Ar3 5.5.1 Table 1 */
46 if (L == 2048 && (N == 224 || N == 256))
47 return 112;
48 # ifndef OPENSSL_NO_DH
49 ERR_raise(ERR_LIB_DH, DH_R_BAD_FFC_PARAMETERS);
50 # endif
51 } else if (type == FFC_PARAM_TYPE_DSA) {
52 /* Valid DSA L,N parameters from FIPS 186-4 Section 4.2 */
53 /* In fips mode 1024/160 can only be used for verification */
54 if (verify && L == 1024 && N == 160)
55 return 80;
56 if (L == 2048 && (N == 224 || N == 256))
57 return 112;
58 if (L == 3072 && N == 256)
59 return 128;
60 # ifndef OPENSSL_NO_DSA
61 ERR_raise(ERR_LIB_DSA, DSA_R_BAD_FFC_PARAMETERS);
62 # endif
63 }
64 return 0;
65 }
66 #else
ffc_validate_LN(size_t L,size_t N,int type,int verify)67 static int ffc_validate_LN(size_t L, size_t N, int type, int verify)
68 {
69 if (type == FFC_PARAM_TYPE_DH) {
70 /* Allow legacy 1024/160 in non fips mode */
71 if (L == 1024 && N == 160)
72 return 80;
73 /* Valid DH L,N parameters from SP800-56Ar3 5.5.1 Table 1 */
74 if (L == 2048 && (N == 224 || N == 256))
75 return 112;
76 # ifndef OPENSSL_NO_DH
77 ERR_raise(ERR_LIB_DH, DH_R_BAD_FFC_PARAMETERS);
78 # endif
79 } else if (type == FFC_PARAM_TYPE_DSA) {
80 if (L >= 3072 && N >= 256)
81 return 128;
82 if (L >= 2048 && N >= 224)
83 return 112;
84 if (L >= 1024 && N >= 160)
85 return 80;
86 # ifndef OPENSSL_NO_DSA
87 ERR_raise(ERR_LIB_DSA, DSA_R_BAD_FFC_PARAMETERS);
88 # endif
89 }
90 return 0;
91 }
92 #endif /* FIPS_MODULE */
93
94 /* FIPS186-4 A.2.1 Unverifiable Generation of Generator g */
generate_unverifiable_g(BN_CTX * ctx,BN_MONT_CTX * mont,BIGNUM * g,BIGNUM * hbn,const BIGNUM * p,const BIGNUM * e,const BIGNUM * pm1,int * hret)95 static int generate_unverifiable_g(BN_CTX *ctx, BN_MONT_CTX *mont, BIGNUM *g,
96 BIGNUM *hbn, const BIGNUM *p,
97 const BIGNUM *e,const BIGNUM *pm1,
98 int *hret)
99 {
100 int h = 2;
101
102 /* Step (2): choose h (where 1 < h)*/
103 if (!BN_set_word(hbn, h))
104 return 0;
105
106 for (;;) {
107 /* Step (3): g = h^e % p */
108 if (!BN_mod_exp_mont(g, hbn, e, p, ctx, mont))
109 return 0;
110 /* Step (4): Finish if g > 1 */
111 if (BN_cmp(g, BN_value_one()) > 0)
112 break;
113
114 /* Step (2) Choose any h in the range 1 < h < (p-1) */
115 if (!BN_add_word(hbn, 1) || BN_cmp(hbn, pm1) >= 0)
116 return 0;
117 ++h;
118 }
119 *hret = h;
120 return 1;
121 }
122
123 /*
124 * FIPS186-4 A.2 Generation of canonical generator g.
125 *
126 * It requires the following values as input:
127 * 'evpmd' digest, 'p' prime, 'e' cofactor, gindex and seed.
128 * tmp is a passed in temporary BIGNUM.
129 * mont is used in a BN_mod_exp_mont() with a modulus of p.
130 * Returns a value in g.
131 */
generate_canonical_g(BN_CTX * ctx,BN_MONT_CTX * mont,const EVP_MD * evpmd,BIGNUM * g,BIGNUM * tmp,const BIGNUM * p,const BIGNUM * e,int gindex,unsigned char * seed,size_t seedlen)132 static int generate_canonical_g(BN_CTX *ctx, BN_MONT_CTX *mont,
133 const EVP_MD *evpmd, BIGNUM *g, BIGNUM *tmp,
134 const BIGNUM *p, const BIGNUM *e,
135 int gindex, unsigned char *seed, size_t seedlen)
136 {
137 int ret = 0;
138 int counter = 1;
139 unsigned char md[EVP_MAX_MD_SIZE];
140 EVP_MD_CTX *mctx = NULL;
141 int mdsize;
142
143 mdsize = EVP_MD_get_size(evpmd);
144 if (mdsize <= 0)
145 return 0;
146
147 mctx = EVP_MD_CTX_new();
148 if (mctx == NULL)
149 return 0;
150
151 /*
152 * A.2.3 Step (4) & (5)
153 * A.2.4 Step (6) & (7)
154 * counter = 0; counter += 1
155 */
156 for (counter = 1; counter <= 0xFFFF; ++counter) {
157 /*
158 * A.2.3 Step (7) & (8) & (9)
159 * A.2.4 Step (9) & (10) & (11)
160 * W = Hash(seed || "ggen" || index || counter)
161 * g = W^e % p
162 */
163 static const unsigned char ggen[4] = { 0x67, 0x67, 0x65, 0x6e };
164
165 md[0] = (unsigned char)(gindex & 0xff);
166 md[1] = (unsigned char)((counter >> 8) & 0xff);
167 md[2] = (unsigned char)(counter & 0xff);
168 if (!EVP_DigestInit_ex(mctx, evpmd, NULL)
169 || !EVP_DigestUpdate(mctx, seed, seedlen)
170 || !EVP_DigestUpdate(mctx, ggen, sizeof(ggen))
171 || !EVP_DigestUpdate(mctx, md, 3)
172 || !EVP_DigestFinal_ex(mctx, md, NULL)
173 || (BN_bin2bn(md, mdsize, tmp) == NULL)
174 || !BN_mod_exp_mont(g, tmp, e, p, ctx, mont))
175 break; /* exit on failure */
176 /*
177 * A.2.3 Step (10)
178 * A.2.4 Step (12)
179 * Found a value for g if (g >= 2)
180 */
181 if (BN_cmp(g, BN_value_one()) > 0) {
182 ret = 1;
183 break; /* found g */
184 }
185 }
186 EVP_MD_CTX_free(mctx);
187 return ret;
188 }
189
190 /* Generation of p is the same for FIPS 186-4 & FIPS 186-2 */
generate_p(BN_CTX * ctx,const EVP_MD * evpmd,int max_counter,int n,unsigned char * buf,size_t buf_len,const BIGNUM * q,BIGNUM * p,int L,BN_GENCB * cb,int * counter,int * res)191 static int generate_p(BN_CTX *ctx, const EVP_MD *evpmd, int max_counter, int n,
192 unsigned char *buf, size_t buf_len, const BIGNUM *q,
193 BIGNUM *p, int L, BN_GENCB *cb, int *counter,
194 int *res)
195 {
196 int ret = -1;
197 int i, j, k, r;
198 unsigned char md[EVP_MAX_MD_SIZE];
199 int mdsize;
200 BIGNUM *W, *X, *tmp, *c, *test;
201
202 BN_CTX_start(ctx);
203 W = BN_CTX_get(ctx);
204 X = BN_CTX_get(ctx);
205 c = BN_CTX_get(ctx);
206 test = BN_CTX_get(ctx);
207 tmp = BN_CTX_get(ctx);
208 if (tmp == NULL)
209 goto err;
210
211 if (!BN_lshift(test, BN_value_one(), L - 1))
212 goto err;
213
214 mdsize = EVP_MD_get_size(evpmd);
215 if (mdsize <= 0)
216 goto err;
217
218 /* A.1.1.2 Step (10) AND
219 * A.1.1.2 Step (12)
220 * offset = 1 (this is handled below)
221 */
222 /*
223 * A.1.1.2 Step (11) AND
224 * A.1.1.3 Step (13)
225 */
226 for (i = 0; i <= max_counter; i++) {
227 if ((i != 0) && !BN_GENCB_call(cb, 0, i))
228 goto err;
229
230 BN_zero(W);
231 /* seed_tmp buffer contains "seed + offset - 1" */
232 for (j = 0; j <= n; j++) {
233 /* obtain "seed + offset + j" by incrementing by 1: */
234 for (k = (int)buf_len - 1; k >= 0; k--) {
235 buf[k]++;
236 if (buf[k] != 0)
237 break;
238 }
239 /*
240 * A.1.1.2 Step (11.1) AND
241 * A.1.1.3 Step (13.1)
242 * tmp = V(j) = Hash((seed + offset + j) % 2^seedlen)
243 */
244 if (!EVP_Digest(buf, buf_len, md, NULL, evpmd, NULL)
245 || (BN_bin2bn(md, mdsize, tmp) == NULL)
246 /*
247 * A.1.1.2 Step (11.2)
248 * A.1.1.3 Step (13.2)
249 * W += V(j) * 2^(outlen * j)
250 */
251 || !BN_lshift(tmp, tmp, (mdsize << 3) * j)
252 || !BN_add(W, W, tmp))
253 goto err;
254 }
255
256 /*
257 * A.1.1.2 Step (11.3) AND
258 * A.1.1.3 Step (13.3)
259 * X = W + 2^(L-1) where W < 2^(L-1)
260 */
261 if (!BN_mask_bits(W, L - 1)
262 || !BN_copy(X, W)
263 || !BN_add(X, X, test)
264 /*
265 * A.1.1.2 Step (11.4) AND
266 * A.1.1.3 Step (13.4)
267 * c = X mod 2q
268 */
269 || !BN_lshift1(tmp, q)
270 || !BN_mod(c, X, tmp, ctx)
271 /*
272 * A.1.1.2 Step (11.5) AND
273 * A.1.1.3 Step (13.5)
274 * p = X - (c - 1)
275 */
276 || !BN_sub(tmp, c, BN_value_one())
277 || !BN_sub(p, X, tmp))
278 goto err;
279
280 /*
281 * A.1.1.2 Step (11.6) AND
282 * A.1.1.3 Step (13.6)
283 * if (p < 2 ^ (L-1)) continue
284 * This makes sure the top bit is set.
285 */
286 if (BN_cmp(p, test) >= 0) {
287 /*
288 * A.1.1.2 Step (11.7) AND
289 * A.1.1.3 Step (13.7)
290 * Test if p is prime
291 * (This also makes sure the bottom bit is set)
292 */
293 r = BN_check_prime(p, ctx, cb);
294 /* A.1.1.2 Step (11.8) : Return if p is prime */
295 if (r > 0) {
296 *counter = i;
297 ret = 1; /* return success */
298 goto err;
299 }
300 if (r != 0)
301 goto err;
302 }
303 /* Step (11.9) : offset = offset + n + 1 is done auto-magically */
304 }
305 /* No prime P found */
306 ret = 0;
307 *res |= FFC_CHECK_P_NOT_PRIME;
308 err:
309 BN_CTX_end(ctx);
310 return ret;
311 }
312
generate_q_fips186_4(BN_CTX * ctx,BIGNUM * q,const EVP_MD * evpmd,int qsize,unsigned char * seed,size_t seedlen,int generate_seed,int * retm,int * res,BN_GENCB * cb)313 static int generate_q_fips186_4(BN_CTX *ctx, BIGNUM *q, const EVP_MD *evpmd,
314 int qsize, unsigned char *seed, size_t seedlen,
315 int generate_seed, int *retm, int *res,
316 BN_GENCB *cb)
317 {
318 int ret = 0, r;
319 int m = *retm;
320 unsigned char md[EVP_MAX_MD_SIZE];
321 int mdsize = EVP_MD_get_size(evpmd);
322 unsigned char *pmd;
323 OSSL_LIB_CTX *libctx = ossl_bn_get_libctx(ctx);
324
325 /* find q */
326 for (;;) {
327 if(!BN_GENCB_call(cb, 0, m++))
328 goto err;
329
330 /* A.1.1.2 Step (5) : generate seed with size seed_len */
331 if (generate_seed
332 && RAND_bytes_ex(libctx, seed, seedlen, 0) < 0)
333 goto err;
334 /*
335 * A.1.1.2 Step (6) AND
336 * A.1.1.3 Step (7)
337 * U = Hash(seed) % (2^(N-1))
338 */
339 if (!EVP_Digest(seed, seedlen, md, NULL, evpmd, NULL))
340 goto err;
341 /* Take least significant bits of md */
342 if (mdsize > qsize)
343 pmd = md + mdsize - qsize;
344 else
345 pmd = md;
346 if (mdsize < qsize)
347 memset(md + mdsize, 0, qsize - mdsize);
348
349 /*
350 * A.1.1.2 Step (7) AND
351 * A.1.1.3 Step (8)
352 * q = U + 2^(N-1) + (1 - U %2) (This sets top and bottom bits)
353 */
354 pmd[0] |= 0x80;
355 pmd[qsize-1] |= 0x01;
356 if (!BN_bin2bn(pmd, qsize, q))
357 goto err;
358
359 /*
360 * A.1.1.2 Step (8) AND
361 * A.1.1.3 Step (9)
362 * Test if q is prime
363 */
364 r = BN_check_prime(q, ctx, cb);
365 if (r > 0) {
366 ret = 1;
367 goto err;
368 }
369 /*
370 * A.1.1.3 Step (9) : If the provided seed didn't produce a prime q
371 * return an error.
372 */
373 if (!generate_seed) {
374 *res |= FFC_CHECK_Q_NOT_PRIME;
375 goto err;
376 }
377 if (r != 0)
378 goto err;
379 /* A.1.1.2 Step (9) : if q is not prime, try another q */
380 }
381 err:
382 *retm = m;
383 return ret;
384 }
385
generate_q_fips186_2(BN_CTX * ctx,BIGNUM * q,const EVP_MD * evpmd,unsigned char * buf,unsigned char * seed,size_t qsize,int generate_seed,int * retm,int * res,BN_GENCB * cb)386 static int generate_q_fips186_2(BN_CTX *ctx, BIGNUM *q, const EVP_MD *evpmd,
387 unsigned char *buf, unsigned char *seed,
388 size_t qsize, int generate_seed, int *retm,
389 int *res, BN_GENCB *cb)
390 {
391 unsigned char buf2[EVP_MAX_MD_SIZE];
392 unsigned char md[EVP_MAX_MD_SIZE];
393 int i, r, ret = 0, m = *retm;
394 OSSL_LIB_CTX *libctx = ossl_bn_get_libctx(ctx);
395
396 /* find q */
397 for (;;) {
398 /* step 1 */
399 if (!BN_GENCB_call(cb, 0, m++))
400 goto err;
401
402 if (generate_seed && RAND_bytes_ex(libctx, seed, qsize, 0) <= 0)
403 goto err;
404
405 memcpy(buf, seed, qsize);
406 memcpy(buf2, seed, qsize);
407
408 /* precompute "SEED + 1" for step 7: */
409 for (i = (int)qsize - 1; i >= 0; i--) {
410 buf[i]++;
411 if (buf[i] != 0)
412 break;
413 }
414
415 /* step 2 */
416 if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL))
417 goto err;
418 if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL))
419 goto err;
420 for (i = 0; i < (int)qsize; i++)
421 md[i] ^= buf2[i];
422
423 /* step 3 */
424 md[0] |= 0x80;
425 md[qsize - 1] |= 0x01;
426 if (!BN_bin2bn(md, (int)qsize, q))
427 goto err;
428
429 /* step 4 */
430 r = BN_check_prime(q, ctx, cb);
431 if (r > 0) {
432 /* Found a prime */
433 ret = 1;
434 goto err;
435 }
436 if (r != 0)
437 goto err; /* Exit if error */
438 /* Try another iteration if it wasnt prime - was in old code.. */
439 generate_seed = 1;
440 }
441 err:
442 *retm = m;
443 return ret;
444 }
445
default_mdname(size_t N)446 static const char *default_mdname(size_t N)
447 {
448 if (N == 160)
449 return "SHA1";
450 else if (N == 224)
451 return "SHA-224";
452 else if (N == 256)
453 return "SHA-256";
454 return NULL;
455 }
456
457 /*
458 * FIPS 186-4 FFC parameter generation (as defined in Appendix A).
459 * The same code is used for validation (when validate_flags != 0)
460 *
461 * The primes p & q are generated/validated using:
462 * A.1.1.2 Generation of probable primes p & q using approved hash.
463 * A.1.1.3 Validation of generated probable primes
464 *
465 * Generator 'g' has 2 types in FIPS 186-4:
466 * (1) A.2.1 unverifiable generation of generator g.
467 * A.2.2 Assurance of the validity of unverifiable generator g.
468 * (2) A.2.3 Verifiable Canonical Generation of the generator g.
469 * A.2.4 Validation for Canonical Generation of the generator g.
470 *
471 * Notes:
472 * (1) is only a partial validation of g, The validation of (2) requires
473 * the seed and index used during generation as input.
474 *
475 * params: used to pass in values for generation and validation.
476 * params->md: is the digest to use, If this value is NULL, then the digest is
477 * chosen using the value of N.
478 * params->flags:
479 * For validation one of:
480 * -FFC_PARAM_FLAG_VALIDATE_PQ
481 * -FFC_PARAM_FLAG_VALIDATE_G
482 * -FFC_PARAM_FLAG_VALIDATE_PQG
483 * For generation of p & q:
484 * - This is skipped if p & q are passed in.
485 * - If the seed is passed in then generation of p & q uses this seed (and if
486 * this fails an error will occur).
487 * - Otherwise the seed is generated, and values of p & q are generated and
488 * the value of seed and counter are optionally returned.
489 * For the generation of g (after the generation of p, q):
490 * - If the seed has been generated or passed in and a valid gindex is passed
491 * in then canonical generation of g is used otherwise unverifiable
492 * generation of g is chosen.
493 * For validation of p & q:
494 * - p, q, and the seed and counter used for generation must be passed in.
495 * For validation of g:
496 * - For a partial validation : p, q and g are required.
497 * - For a canonical validation : the gindex and seed used for generation are
498 * also required.
499 * mode: The mode - either FFC_PARAM_MODE_GENERATE or FFC_PARAM_MODE_VERIFY.
500 * type: The key type - FFC_PARAM_TYPE_DSA or FFC_PARAM_TYPE_DH.
501 * L: is the size of the prime p in bits (e.g 2048)
502 * N: is the size of the prime q in bits (e.g 256)
503 * res: A returned failure reason (One of FFC_CHECK_XXXX),
504 * or 0 for general failures.
505 * cb: A callback (can be NULL) that is called during different phases
506 *
507 * Returns:
508 * - FFC_PARAM_RET_STATUS_FAILED: if there was an error, or validation failed.
509 * - FFC_PARAM_RET_STATUS_SUCCESS if the generation or validation succeeded.
510 * - FFC_PARAM_RET_STATUS_UNVERIFIABLE_G if the validation of G succeeded,
511 * but G is unverifiable.
512 */
ossl_ffc_params_FIPS186_4_gen_verify(OSSL_LIB_CTX * libctx,FFC_PARAMS * params,int mode,int type,size_t L,size_t N,int * res,BN_GENCB * cb)513 int ossl_ffc_params_FIPS186_4_gen_verify(OSSL_LIB_CTX *libctx,
514 FFC_PARAMS *params, int mode, int type,
515 size_t L, size_t N, int *res,
516 BN_GENCB *cb)
517 {
518 int ok = FFC_PARAM_RET_STATUS_FAILED;
519 unsigned char *seed = NULL, *seed_tmp = NULL;
520 int mdsize, counter = 0, pcounter = 0, r = 0;
521 size_t seedlen = 0;
522 BIGNUM *tmp, *pm1, *e, *test;
523 BIGNUM *g = NULL, *q = NULL, *p = NULL;
524 BN_MONT_CTX *mont = NULL;
525 int n = 0, m = 0, qsize;
526 int canonical_g = 0, hret = 0;
527 BN_CTX *ctx = NULL;
528 EVP_MD_CTX *mctx = NULL;
529 EVP_MD *md = NULL;
530 int verify = (mode == FFC_PARAM_MODE_VERIFY);
531 unsigned int flags = verify ? params->flags : 0;
532 const char *def_name;
533
534 *res = 0;
535
536 if (params->mdname != NULL) {
537 md = EVP_MD_fetch(libctx, params->mdname, params->mdprops);
538 } else {
539 if (N == 0)
540 N = (L >= 2048 ? SHA256_DIGEST_LENGTH : SHA_DIGEST_LENGTH) * 8;
541 def_name = default_mdname(N);
542 if (def_name == NULL) {
543 *res = FFC_CHECK_INVALID_Q_VALUE;
544 goto err;
545 }
546 md = EVP_MD_fetch(libctx, def_name, params->mdprops);
547 }
548 if (md == NULL)
549 goto err;
550 mdsize = EVP_MD_get_size(md);
551 if (mdsize <= 0)
552 goto err;
553
554 if (N == 0)
555 N = mdsize * 8;
556 qsize = N >> 3;
557
558 /*
559 * A.1.1.2 Step (1) AND
560 * A.1.1.3 Step (3)
561 * Check that the L,N pair is an acceptable pair.
562 */
563 if (L <= N || !ffc_validate_LN(L, N, type, verify)) {
564 *res = FFC_CHECK_BAD_LN_PAIR;
565 goto err;
566 }
567
568 mctx = EVP_MD_CTX_new();
569 if (mctx == NULL)
570 goto err;
571
572 if ((ctx = BN_CTX_new_ex(libctx)) == NULL)
573 goto err;
574
575 BN_CTX_start(ctx);
576 g = BN_CTX_get(ctx);
577 pm1 = BN_CTX_get(ctx);
578 e = BN_CTX_get(ctx);
579 test = BN_CTX_get(ctx);
580 tmp = BN_CTX_get(ctx);
581 if (tmp == NULL)
582 goto err;
583
584 seedlen = params->seedlen;
585 if (seedlen == 0)
586 seedlen = (size_t)mdsize;
587 /* If the seed was passed in - use this value as the seed */
588 if (params->seed != NULL)
589 seed = params->seed;
590
591 if (!verify) {
592 /* For generation: p & q must both be NULL or NON-NULL */
593 if ((params->p == NULL) != (params->q == NULL)) {
594 *res = FFC_CHECK_INVALID_PQ;
595 goto err;
596 }
597 } else {
598 /* Validation of p,q requires seed and counter to be valid */
599 if ((flags & FFC_PARAM_FLAG_VALIDATE_PQ) != 0) {
600 if (seed == NULL || params->pcounter < 0) {
601 *res = FFC_CHECK_MISSING_SEED_OR_COUNTER;
602 goto err;
603 }
604 }
605 if ((flags & FFC_PARAM_FLAG_VALIDATE_G) != 0) {
606 /* validation of g also requires g to be set */
607 if (params->g == NULL) {
608 *res = FFC_CHECK_INVALID_G;
609 goto err;
610 }
611 }
612 }
613
614 /*
615 * If p & q are passed in and
616 * validate_flags = 0 then skip the generation of PQ.
617 * validate_flags = VALIDATE_G then also skip the validation of PQ.
618 */
619 if (params->p != NULL && ((flags & FFC_PARAM_FLAG_VALIDATE_PQ) == 0)) {
620 /* p and q already exists so only generate g */
621 p = params->p;
622 q = params->q;
623 goto g_only;
624 /* otherwise fall thru to validate p & q */
625 }
626
627 /* p & q will be used for generation and validation */
628 p = BN_CTX_get(ctx);
629 q = BN_CTX_get(ctx);
630 if (q == NULL)
631 goto err;
632
633 /*
634 * A.1.1.2 Step (2) AND
635 * A.1.1.3 Step (6)
636 * Return invalid if seedlen < N
637 */
638 if ((seedlen * 8) < N) {
639 *res = FFC_CHECK_INVALID_SEED_SIZE;
640 goto err;
641 }
642
643 seed_tmp = OPENSSL_malloc(seedlen);
644 if (seed_tmp == NULL)
645 goto err;
646
647 if (seed == NULL) {
648 /* Validation requires the seed to be supplied */
649 if (verify) {
650 *res = FFC_CHECK_MISSING_SEED_OR_COUNTER;
651 goto err;
652 }
653 /* if the seed is not supplied then alloc a seed buffer */
654 seed = OPENSSL_malloc(seedlen);
655 if (seed == NULL)
656 goto err;
657 }
658
659 /* A.1.1.2 Step (11): max loop count = 4L - 1 */
660 counter = 4 * L - 1;
661 /* Validation requires the counter to be supplied */
662 if (verify) {
663 /* A.1.1.3 Step (4) : if (counter > (4L -1)) return INVALID */
664 if (params->pcounter > counter) {
665 *res = FFC_CHECK_INVALID_COUNTER;
666 goto err;
667 }
668 counter = params->pcounter;
669 }
670
671 /*
672 * A.1.1.2 Step (3) AND
673 * A.1.1.3 Step (10)
674 * n = floor(L / hash_outlen) - 1
675 */
676 n = (L - 1 ) / (mdsize << 3);
677
678 /* Calculate 2^(L-1): Used in step A.1.1.2 Step (11.3) */
679 if (!BN_lshift(test, BN_value_one(), L - 1))
680 goto err;
681
682 for (;;) {
683 if (!generate_q_fips186_4(ctx, q, md, qsize, seed, seedlen,
684 seed != params->seed, &m, res, cb))
685 goto err;
686 /* A.1.1.3 Step (9): Verify that q matches the expected value */
687 if (verify && (BN_cmp(q, params->q) != 0)) {
688 *res = FFC_CHECK_Q_MISMATCH;
689 goto err;
690 }
691 if(!BN_GENCB_call(cb, 2, 0))
692 goto err;
693 if(!BN_GENCB_call(cb, 3, 0))
694 goto err;
695
696 memcpy(seed_tmp, seed, seedlen);
697 r = generate_p(ctx, md, counter, n, seed_tmp, seedlen, q, p, L,
698 cb, &pcounter, res);
699 if (r > 0)
700 break; /* found p */
701 if (r < 0)
702 goto err;
703 /*
704 * A.1.1.3 Step (14):
705 * If we get here we failed to get a p for the given seed. If the
706 * seed is not random then it needs to fail (as it will always fail).
707 */
708 if (seed == params->seed) {
709 *res = FFC_CHECK_P_NOT_PRIME;
710 goto err;
711 }
712 }
713 if(!BN_GENCB_call(cb, 2, 1))
714 goto err;
715 /*
716 * Gets here if we found p.
717 * A.1.1.3 Step (14): return error if i != counter OR computed_p != known_p.
718 */
719 if (verify && (pcounter != counter || (BN_cmp(p, params->p) != 0)))
720 goto err;
721
722 /* If validating p & q only then skip the g validation test */
723 if ((flags & FFC_PARAM_FLAG_VALIDATE_PQG) == FFC_PARAM_FLAG_VALIDATE_PQ)
724 goto pass;
725 g_only:
726 if ((mont = BN_MONT_CTX_new()) == NULL)
727 goto err;
728 if (!BN_MONT_CTX_set(mont, p, ctx))
729 goto err;
730
731 if (((flags & FFC_PARAM_FLAG_VALIDATE_G) != 0)
732 && !ossl_ffc_params_validate_unverifiable_g(ctx, mont, p, q, params->g,
733 tmp, res))
734 goto err;
735
736 /*
737 * A.2.1 Step (1) AND
738 * A.2.3 Step (3) AND
739 * A.2.4 Step (5)
740 * e = (p - 1) / q (i.e- Cofactor 'e' is given by p = q * e + 1)
741 */
742 if (!(BN_sub(pm1, p, BN_value_one()) && BN_div(e, NULL, pm1, q, ctx)))
743 goto err;
744
745 /* Canonical g requires a seed and index to be set */
746 if ((seed != NULL) && (params->gindex != FFC_UNVERIFIABLE_GINDEX)) {
747 canonical_g = 1;
748 if (!generate_canonical_g(ctx, mont, md, g, tmp, p, e,
749 params->gindex, seed, seedlen)) {
750 *res = FFC_CHECK_INVALID_G;
751 goto err;
752 }
753 /* A.2.4 Step (13): Return valid if computed_g == g */
754 if (verify && BN_cmp(g, params->g) != 0) {
755 *res = FFC_CHECK_G_MISMATCH;
756 goto err;
757 }
758 } else if (!verify) {
759 if (!generate_unverifiable_g(ctx, mont, g, tmp, p, e, pm1, &hret))
760 goto err;
761 }
762
763 if (!BN_GENCB_call(cb, 3, 1))
764 goto err;
765
766 if (!verify) {
767 if (p != params->p) {
768 BN_free(params->p);
769 params->p = BN_dup(p);
770 }
771 if (q != params->q) {
772 BN_free(params->q);
773 params->q = BN_dup(q);
774 }
775 if (g != params->g) {
776 BN_free(params->g);
777 params->g = BN_dup(g);
778 }
779 if (params->p == NULL || params->q == NULL || params->g == NULL)
780 goto err;
781 if (!ossl_ffc_params_set_validate_params(params, seed, seedlen,
782 pcounter))
783 goto err;
784 params->h = hret;
785 }
786 pass:
787 if ((flags & FFC_PARAM_FLAG_VALIDATE_G) != 0 && (canonical_g == 0))
788 /* Return for the case where g is partially valid */
789 ok = FFC_PARAM_RET_STATUS_UNVERIFIABLE_G;
790 else
791 ok = FFC_PARAM_RET_STATUS_SUCCESS;
792 err:
793 if (seed != params->seed)
794 OPENSSL_free(seed);
795 OPENSSL_free(seed_tmp);
796 if (ctx != NULL)
797 BN_CTX_end(ctx);
798 BN_CTX_free(ctx);
799 BN_MONT_CTX_free(mont);
800 EVP_MD_CTX_free(mctx);
801 EVP_MD_free(md);
802 return ok;
803 }
804
805 /* Note this function is only used for verification in fips mode */
ossl_ffc_params_FIPS186_2_gen_verify(OSSL_LIB_CTX * libctx,FFC_PARAMS * params,int mode,int type,size_t L,size_t N,int * res,BN_GENCB * cb)806 int ossl_ffc_params_FIPS186_2_gen_verify(OSSL_LIB_CTX *libctx,
807 FFC_PARAMS *params, int mode, int type,
808 size_t L, size_t N, int *res,
809 BN_GENCB *cb)
810 {
811 int ok = FFC_PARAM_RET_STATUS_FAILED;
812 unsigned char seed[SHA256_DIGEST_LENGTH];
813 unsigned char buf[SHA256_DIGEST_LENGTH];
814 BIGNUM *r0, *test, *tmp, *g = NULL, *q = NULL, *p = NULL;
815 BN_MONT_CTX *mont = NULL;
816 EVP_MD *md = NULL;
817 size_t qsize;
818 int n = 0, m = 0;
819 int counter = 0, pcounter = 0, use_random_seed;
820 int rv;
821 BN_CTX *ctx = NULL;
822 int hret = -1;
823 unsigned char *seed_in = params->seed;
824 size_t seed_len = params->seedlen;
825 int verify = (mode == FFC_PARAM_MODE_VERIFY);
826 unsigned int flags = verify ? params->flags : 0;
827 const char *def_name;
828
829 *res = 0;
830
831 if (params->mdname != NULL) {
832 md = EVP_MD_fetch(libctx, params->mdname, params->mdprops);
833 } else {
834 if (N == 0)
835 N = (L >= 2048 ? SHA256_DIGEST_LENGTH : SHA_DIGEST_LENGTH) * 8;
836 def_name = default_mdname(N);
837 if (def_name == NULL) {
838 *res = FFC_CHECK_INVALID_Q_VALUE;
839 goto err;
840 }
841 md = EVP_MD_fetch(libctx, def_name, params->mdprops);
842 }
843 if (md == NULL)
844 goto err;
845 if (N == 0)
846 N = EVP_MD_get_size(md) * 8;
847 qsize = N >> 3;
848
849 /*
850 * The original spec allowed L = 512 + 64*j (j = 0.. 8)
851 * https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-131Ar2.pdf
852 * says that 512 can be used for legacy verification.
853 */
854 if (L < 512) {
855 *res = FFC_CHECK_BAD_LN_PAIR;
856 goto err;
857 }
858 if (qsize != SHA_DIGEST_LENGTH
859 && qsize != SHA224_DIGEST_LENGTH
860 && qsize != SHA256_DIGEST_LENGTH) {
861 /* invalid q size */
862 *res = FFC_CHECK_INVALID_Q_VALUE;
863 goto err;
864 }
865
866 L = (L + 63) / 64 * 64;
867
868 if (seed_in != NULL) {
869 if (seed_len < qsize) {
870 *res = FFC_CHECK_INVALID_SEED_SIZE;
871 goto err;
872 }
873 /* Only consume as much seed as is expected. */
874 if (seed_len > qsize)
875 seed_len = qsize;
876 memcpy(seed, seed_in, seed_len);
877 }
878
879 ctx = BN_CTX_new_ex(libctx);
880 if (ctx == NULL)
881 goto err;
882
883 BN_CTX_start(ctx);
884
885 r0 = BN_CTX_get(ctx);
886 g = BN_CTX_get(ctx);
887 q = BN_CTX_get(ctx);
888 p = BN_CTX_get(ctx);
889 tmp = BN_CTX_get(ctx);
890 test = BN_CTX_get(ctx);
891 if (test == NULL)
892 goto err;
893
894 if (!BN_lshift(test, BN_value_one(), L - 1))
895 goto err;
896
897 if (!verify) {
898 /* For generation: p & q must both be NULL or NON-NULL */
899 if ((params->p != NULL) != (params->q != NULL)) {
900 *res = FFC_CHECK_INVALID_PQ;
901 goto err;
902 }
903 } else {
904 if ((flags & FFC_PARAM_FLAG_VALIDATE_PQ) != 0) {
905 /* Validation of p,q requires seed and counter to be valid */
906 if (seed_in == NULL || params->pcounter < 0) {
907 *res = FFC_CHECK_MISSING_SEED_OR_COUNTER;
908 goto err;
909 }
910 }
911 if ((flags & FFC_PARAM_FLAG_VALIDATE_G) != 0) {
912 /* validation of g also requires g to be set */
913 if (params->g == NULL) {
914 *res = FFC_CHECK_INVALID_G;
915 goto err;
916 }
917 }
918 }
919
920 if (params->p != NULL && ((flags & FFC_PARAM_FLAG_VALIDATE_PQ) == 0)) {
921 /* p and q already exists so only generate g */
922 p = params->p;
923 q = params->q;
924 goto g_only;
925 /* otherwise fall thru to validate p and q */
926 }
927
928 use_random_seed = (seed_in == NULL);
929 for (;;) {
930 if (!generate_q_fips186_2(ctx, q, md, buf, seed, qsize,
931 use_random_seed, &m, res, cb))
932 goto err;
933
934 if (!BN_GENCB_call(cb, 2, 0))
935 goto err;
936 if (!BN_GENCB_call(cb, 3, 0))
937 goto err;
938
939 /* step 6 */
940 n = (L - 1) / 160;
941 counter = 4 * L - 1; /* Was 4096 */
942 /* Validation requires the counter to be supplied */
943 if (verify) {
944 if (params->pcounter > counter) {
945 *res = FFC_CHECK_INVALID_COUNTER;
946 goto err;
947 }
948 counter = params->pcounter;
949 }
950
951 rv = generate_p(ctx, md, counter, n, buf, qsize, q, p, L, cb,
952 &pcounter, res);
953 if (rv > 0)
954 break; /* found it */
955 if (rv == -1)
956 goto err;
957 /* This is what the old code did - probably not a good idea! */
958 use_random_seed = 1;
959 }
960
961 if (!BN_GENCB_call(cb, 2, 1))
962 goto err;
963
964 if (verify) {
965 if (pcounter != counter) {
966 *res = FFC_CHECK_COUNTER_MISMATCH;
967 goto err;
968 }
969 if (BN_cmp(p, params->p) != 0) {
970 *res = FFC_CHECK_P_MISMATCH;
971 goto err;
972 }
973 }
974 /* If validating p & q only then skip the g validation test */
975 if ((flags & FFC_PARAM_FLAG_VALIDATE_PQG) == FFC_PARAM_FLAG_VALIDATE_PQ)
976 goto pass;
977 g_only:
978 if ((mont = BN_MONT_CTX_new()) == NULL)
979 goto err;
980 if (!BN_MONT_CTX_set(mont, p, ctx))
981 goto err;
982
983 if (!verify) {
984 /* We now need to generate g */
985 /* set test = p - 1 */
986 if (!BN_sub(test, p, BN_value_one()))
987 goto err;
988 /* Set r0 = (p - 1) / q */
989 if (!BN_div(r0, NULL, test, q, ctx))
990 goto err;
991 if (!generate_unverifiable_g(ctx, mont, g, tmp, p, r0, test, &hret))
992 goto err;
993 } else if (((flags & FFC_PARAM_FLAG_VALIDATE_G) != 0)
994 && !ossl_ffc_params_validate_unverifiable_g(ctx, mont, p, q,
995 params->g, tmp,
996 res)) {
997 goto err;
998 }
999
1000 if (!BN_GENCB_call(cb, 3, 1))
1001 goto err;
1002
1003 if (!verify) {
1004 if (p != params->p) {
1005 BN_free(params->p);
1006 params->p = BN_dup(p);
1007 }
1008 if (q != params->q) {
1009 BN_free(params->q);
1010 params->q = BN_dup(q);
1011 }
1012 if (g != params->g) {
1013 BN_free(params->g);
1014 params->g = BN_dup(g);
1015 }
1016 if (params->p == NULL || params->q == NULL || params->g == NULL)
1017 goto err;
1018 if (!ossl_ffc_params_set_validate_params(params, seed, qsize, pcounter))
1019 goto err;
1020 params->h = hret;
1021 }
1022 pass:
1023 if ((flags & FFC_PARAM_FLAG_VALIDATE_G) != 0)
1024 ok = FFC_PARAM_RET_STATUS_UNVERIFIABLE_G;
1025 else
1026 ok = FFC_PARAM_RET_STATUS_SUCCESS;
1027 err:
1028 if (ctx != NULL)
1029 BN_CTX_end(ctx);
1030 BN_CTX_free(ctx);
1031 BN_MONT_CTX_free(mont);
1032 EVP_MD_free(md);
1033 return ok;
1034 }
1035
ossl_ffc_params_FIPS186_4_generate(OSSL_LIB_CTX * libctx,FFC_PARAMS * params,int type,size_t L,size_t N,int * res,BN_GENCB * cb)1036 int ossl_ffc_params_FIPS186_4_generate(OSSL_LIB_CTX *libctx, FFC_PARAMS *params,
1037 int type, size_t L, size_t N,
1038 int *res, BN_GENCB *cb)
1039 {
1040 return ossl_ffc_params_FIPS186_4_gen_verify(libctx, params,
1041 FFC_PARAM_MODE_GENERATE,
1042 type, L, N, res, cb);
1043 }
1044
1045 /* This should no longer be used in FIPS mode */
ossl_ffc_params_FIPS186_2_generate(OSSL_LIB_CTX * libctx,FFC_PARAMS * params,int type,size_t L,size_t N,int * res,BN_GENCB * cb)1046 int ossl_ffc_params_FIPS186_2_generate(OSSL_LIB_CTX *libctx, FFC_PARAMS *params,
1047 int type, size_t L, size_t N,
1048 int *res, BN_GENCB *cb)
1049 {
1050 if (!ossl_ffc_params_FIPS186_2_gen_verify(libctx, params,
1051 FFC_PARAM_MODE_GENERATE,
1052 type, L, N, res, cb))
1053 return 0;
1054
1055 ossl_ffc_params_enable_flags(params, FFC_PARAM_FLAG_VALIDATE_LEGACY, 1);
1056 return 1;
1057 }
1058