Disconnect hostapd from building in base
[dragonfly.git] / contrib / hostapd / src / common / sae.c
CommitLineData
4781064b
JM
1/*
2 * Simultaneous authentication of equals
3 * Copyright (c) 2012-2013, Jouni Malinen <j@w1.fi>
4 *
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
7 */
8
9#include "includes.h"
10
11#include "common.h"
12#include "crypto/crypto.h"
13#include "crypto/sha256.h"
14#include "crypto/random.h"
15#include "crypto/dh_groups.h"
16#include "ieee802_11_defs.h"
17#include "sae.h"
18
19
20int sae_set_group(struct sae_data *sae, int group)
21{
22 struct sae_temporary_data *tmp;
23
24 sae_clear_data(sae);
25 tmp = sae->tmp = os_zalloc(sizeof(*tmp));
26 if (tmp == NULL)
27 return -1;
28
29 /* First, check if this is an ECC group */
30 tmp->ec = crypto_ec_init(group);
31 if (tmp->ec) {
32 sae->group = group;
33 tmp->prime_len = crypto_ec_prime_len(tmp->ec);
34 tmp->prime = crypto_ec_get_prime(tmp->ec);
35 tmp->order = crypto_ec_get_order(tmp->ec);
36 return 0;
37 }
38
39 /* Not an ECC group, check FFC */
40 tmp->dh = dh_groups_get(group);
41 if (tmp->dh) {
42 sae->group = group;
43 tmp->prime_len = tmp->dh->prime_len;
44 if (tmp->prime_len > SAE_MAX_PRIME_LEN) {
45 sae_clear_data(sae);
46 return -1;
47 }
48
49 tmp->prime_buf = crypto_bignum_init_set(tmp->dh->prime,
50 tmp->prime_len);
51 if (tmp->prime_buf == NULL) {
52 sae_clear_data(sae);
53 return -1;
54 }
55 tmp->prime = tmp->prime_buf;
56
57 tmp->order_buf = crypto_bignum_init_set(tmp->dh->order,
58 tmp->dh->order_len);
59 if (tmp->order_buf == NULL) {
60 sae_clear_data(sae);
61 return -1;
62 }
63 tmp->order = tmp->order_buf;
64
65 return 0;
66 }
67
68 /* Unsupported group */
69 return -1;
70}
71
72
73void sae_clear_temp_data(struct sae_data *sae)
74{
75 struct sae_temporary_data *tmp;
76 if (sae == NULL || sae->tmp == NULL)
77 return;
78 tmp = sae->tmp;
79 crypto_ec_deinit(tmp->ec);
80 crypto_bignum_deinit(tmp->prime_buf, 0);
81 crypto_bignum_deinit(tmp->order_buf, 0);
82 crypto_bignum_deinit(tmp->sae_rand, 1);
83 crypto_bignum_deinit(tmp->pwe_ffc, 1);
84 crypto_bignum_deinit(tmp->own_commit_scalar, 0);
85 crypto_bignum_deinit(tmp->own_commit_element_ffc, 0);
86 crypto_bignum_deinit(tmp->peer_commit_element_ffc, 0);
87 crypto_ec_point_deinit(tmp->pwe_ecc, 1);
88 crypto_ec_point_deinit(tmp->own_commit_element_ecc, 0);
89 crypto_ec_point_deinit(tmp->peer_commit_element_ecc, 0);
90 os_free(sae->tmp);
91 sae->tmp = NULL;
92}
93
94
95void sae_clear_data(struct sae_data *sae)
96{
97 if (sae == NULL)
98 return;
99 sae_clear_temp_data(sae);
100 crypto_bignum_deinit(sae->peer_commit_scalar, 0);
101 os_memset(sae, 0, sizeof(*sae));
102}
103
104
105static void buf_shift_right(u8 *buf, size_t len, size_t bits)
106{
107 size_t i;
108 for (i = len - 1; i > 0; i--)
109 buf[i] = (buf[i - 1] << (8 - bits)) | (buf[i] >> bits);
110 buf[0] >>= bits;
111}
112
113
114static struct crypto_bignum * sae_get_rand(struct sae_data *sae)
115{
116 u8 val[SAE_MAX_PRIME_LEN];
117 int iter = 0;
118 struct crypto_bignum *bn = NULL;
119 int order_len_bits = crypto_bignum_bits(sae->tmp->order);
120 size_t order_len = (order_len_bits + 7) / 8;
121
122 if (order_len > sizeof(val))
123 return NULL;
124
125 for (;;) {
126 if (iter++ > 100)
127 return NULL;
128 if (random_get_bytes(val, order_len) < 0)
129 return NULL;
130 if (order_len_bits % 8)
131 buf_shift_right(val, order_len, 8 - order_len_bits % 8);
132 bn = crypto_bignum_init_set(val, order_len);
133 if (bn == NULL)
134 return NULL;
135 if (crypto_bignum_is_zero(bn) ||
136 crypto_bignum_is_one(bn) ||
137 crypto_bignum_cmp(bn, sae->tmp->order) >= 0)
138 continue;
139 break;
140 }
141
142 os_memset(val, 0, order_len);
143 return bn;
144}
145
146
147static struct crypto_bignum * sae_get_rand_and_mask(struct sae_data *sae)
148{
149 crypto_bignum_deinit(sae->tmp->sae_rand, 1);
150 sae->tmp->sae_rand = sae_get_rand(sae);
151 if (sae->tmp->sae_rand == NULL)
152 return NULL;
153 return sae_get_rand(sae);
154}
155
156
157static void sae_pwd_seed_key(const u8 *addr1, const u8 *addr2, u8 *key)
158{
159 wpa_printf(MSG_DEBUG, "SAE: PWE derivation - addr1=" MACSTR
160 " addr2=" MACSTR, MAC2STR(addr1), MAC2STR(addr2));
161 if (os_memcmp(addr1, addr2, ETH_ALEN) > 0) {
162 os_memcpy(key, addr1, ETH_ALEN);
163 os_memcpy(key + ETH_ALEN, addr2, ETH_ALEN);
164 } else {
165 os_memcpy(key, addr2, ETH_ALEN);
166 os_memcpy(key + ETH_ALEN, addr1, ETH_ALEN);
167 }
168}
169
170
171static int sae_test_pwd_seed_ecc(struct sae_data *sae, const u8 *pwd_seed,
172 struct crypto_ec_point *pwe)
173{
174 u8 pwd_value[SAE_MAX_ECC_PRIME_LEN], prime[SAE_MAX_ECC_PRIME_LEN];
175 struct crypto_bignum *x;
176 int y_bit;
177 size_t bits;
178
179 if (crypto_bignum_to_bin(sae->tmp->prime, prime, sizeof(prime),
180 sae->tmp->prime_len) < 0)
181 return -1;
182
183 wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-seed", pwd_seed, SHA256_MAC_LEN);
184
185 /* pwd-value = KDF-z(pwd-seed, "SAE Hunting and Pecking", p) */
186 bits = crypto_ec_prime_len_bits(sae->tmp->ec);
187 sha256_prf_bits(pwd_seed, SHA256_MAC_LEN, "SAE Hunting and Pecking",
188 prime, sae->tmp->prime_len, pwd_value, bits);
189 if (bits % 8)
190 buf_shift_right(pwd_value, sizeof(pwd_value), 8 - bits % 8);
191 wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value",
192 pwd_value, sae->tmp->prime_len);
193
194 if (os_memcmp(pwd_value, prime, sae->tmp->prime_len) >= 0)
195 return 0;
196
197 y_bit = pwd_seed[SHA256_MAC_LEN - 1] & 0x01;
198
199 x = crypto_bignum_init_set(pwd_value, sae->tmp->prime_len);
200 if (x == NULL)
201 return -1;
202 if (crypto_ec_point_solve_y_coord(sae->tmp->ec, pwe, x, y_bit) < 0) {
203 crypto_bignum_deinit(x, 0);
204 wpa_printf(MSG_DEBUG, "SAE: No solution found");
205 return 0;
206 }
207 crypto_bignum_deinit(x, 0);
208
209 wpa_printf(MSG_DEBUG, "SAE: PWE found");
210
211 return 1;
212}
213
214
215static int sae_test_pwd_seed_ffc(struct sae_data *sae, const u8 *pwd_seed,
216 struct crypto_bignum *pwe)
217{
218 u8 pwd_value[SAE_MAX_PRIME_LEN];
219 size_t bits = sae->tmp->prime_len * 8;
220 u8 exp[1];
221 struct crypto_bignum *a, *b;
222 int res;
223
224 wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-seed", pwd_seed, SHA256_MAC_LEN);
225
226 /* pwd-value = KDF-z(pwd-seed, "SAE Hunting and Pecking", p) */
227 sha256_prf_bits(pwd_seed, SHA256_MAC_LEN, "SAE Hunting and Pecking",
228 sae->tmp->dh->prime, sae->tmp->prime_len, pwd_value,
229 bits);
230 if (bits % 8)
231 buf_shift_right(pwd_value, sizeof(pwd_value), 8 - bits % 8);
232 wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value", pwd_value,
233 sae->tmp->prime_len);
234
235 if (os_memcmp(pwd_value, sae->tmp->dh->prime, sae->tmp->prime_len) >= 0)
236 {
237 wpa_printf(MSG_DEBUG, "SAE: pwd-value >= p");
238 return 0;
239 }
240
241 /* PWE = pwd-value^((p-1)/r) modulo p */
242
243 a = crypto_bignum_init_set(pwd_value, sae->tmp->prime_len);
244
245 if (sae->tmp->dh->safe_prime) {
246 /*
247 * r = (p-1)/2 for the group used here, so this becomes:
248 * PWE = pwd-value^2 modulo p
249 */
250 exp[0] = 2;
251 b = crypto_bignum_init_set(exp, sizeof(exp));
252 } else {
253 /* Calculate exponent: (p-1)/r */
254 exp[0] = 1;
255 b = crypto_bignum_init_set(exp, sizeof(exp));
256 if (b == NULL ||
257 crypto_bignum_sub(sae->tmp->prime, b, b) < 0 ||
258 crypto_bignum_div(b, sae->tmp->order, b) < 0) {
259 crypto_bignum_deinit(b, 0);
260 b = NULL;
261 }
262 }
263
264 if (a == NULL || b == NULL)
265 res = -1;
266 else
267 res = crypto_bignum_exptmod(a, b, sae->tmp->prime, pwe);
268
269 crypto_bignum_deinit(a, 0);
270 crypto_bignum_deinit(b, 0);
271
272 if (res < 0) {
273 wpa_printf(MSG_DEBUG, "SAE: Failed to calculate PWE");
274 return -1;
275 }
276
277 /* if (PWE > 1) --> found */
278 if (crypto_bignum_is_zero(pwe) || crypto_bignum_is_one(pwe)) {
279 wpa_printf(MSG_DEBUG, "SAE: PWE <= 1");
280 return 0;
281 }
282
283 wpa_printf(MSG_DEBUG, "SAE: PWE found");
284 return 1;
285}
286
287
288static int sae_derive_pwe_ecc(struct sae_data *sae, const u8 *addr1,
289 const u8 *addr2, const u8 *password,
290 size_t password_len)
291{
292 u8 counter, k = 4;
293 u8 addrs[2 * ETH_ALEN];
294 const u8 *addr[2];
295 size_t len[2];
296 int found = 0;
297 struct crypto_ec_point *pwe_tmp;
298
299 if (sae->tmp->pwe_ecc == NULL) {
300 sae->tmp->pwe_ecc = crypto_ec_point_init(sae->tmp->ec);
301 if (sae->tmp->pwe_ecc == NULL)
302 return -1;
303 }
304 pwe_tmp = crypto_ec_point_init(sae->tmp->ec);
305 if (pwe_tmp == NULL)
306 return -1;
307
308 wpa_hexdump_ascii_key(MSG_DEBUG, "SAE: password",
309 password, password_len);
310
311 /*
312 * H(salt, ikm) = HMAC-SHA256(salt, ikm)
313 * pwd-seed = H(MAX(STA-A-MAC, STA-B-MAC) || MIN(STA-A-MAC, STA-B-MAC),
314 * password || counter)
315 */
316 sae_pwd_seed_key(addr1, addr2, addrs);
317
318 addr[0] = password;
319 len[0] = password_len;
320 addr[1] = &counter;
321 len[1] = sizeof(counter);
322
323 /*
324 * Continue for at least k iterations to protect against side-channel
325 * attacks that attempt to determine the number of iterations required
326 * in the loop.
327 */
328 for (counter = 1; counter < k || !found; counter++) {
329 u8 pwd_seed[SHA256_MAC_LEN];
330 int res;
331
332 if (counter > 200) {
333 /* This should not happen in practice */
334 wpa_printf(MSG_DEBUG, "SAE: Failed to derive PWE");
335 break;
336 }
337
338 wpa_printf(MSG_DEBUG, "SAE: counter = %u", counter);
339 if (hmac_sha256_vector(addrs, sizeof(addrs), 2, addr, len,
340 pwd_seed) < 0)
341 break;
342 res = sae_test_pwd_seed_ecc(sae, pwd_seed,
343 found ? pwe_tmp :
344 sae->tmp->pwe_ecc);
345 if (res < 0)
346 break;
347 if (res == 0)
348 continue;
349 if (found) {
350 wpa_printf(MSG_DEBUG, "SAE: Ignore this PWE (one was "
351 "already selected)");
352 } else {
353 wpa_printf(MSG_DEBUG, "SAE: Use this PWE");
354 found = 1;
355 }
356 }
357
358 crypto_ec_point_deinit(pwe_tmp, 1);
359
360 return found ? 0 : -1;
361}
362
363
364static int sae_derive_pwe_ffc(struct sae_data *sae, const u8 *addr1,
365 const u8 *addr2, const u8 *password,
366 size_t password_len)
367{
368 u8 counter;
369 u8 addrs[2 * ETH_ALEN];
370 const u8 *addr[2];
371 size_t len[2];
372 int found = 0;
373
374 if (sae->tmp->pwe_ffc == NULL) {
375 sae->tmp->pwe_ffc = crypto_bignum_init();
376 if (sae->tmp->pwe_ffc == NULL)
377 return -1;
378 }
379
380 wpa_hexdump_ascii_key(MSG_DEBUG, "SAE: password",
381 password, password_len);
382
383 /*
384 * H(salt, ikm) = HMAC-SHA256(salt, ikm)
385 * pwd-seed = H(MAX(STA-A-MAC, STA-B-MAC) || MIN(STA-A-MAC, STA-B-MAC),
386 * password || counter)
387 */
388 sae_pwd_seed_key(addr1, addr2, addrs);
389
390 addr[0] = password;
391 len[0] = password_len;
392 addr[1] = &counter;
393 len[1] = sizeof(counter);
394
395 for (counter = 1; !found; counter++) {
396 u8 pwd_seed[SHA256_MAC_LEN];
397 int res;
398
399 if (counter > 200) {
400 /* This should not happen in practice */
401 wpa_printf(MSG_DEBUG, "SAE: Failed to derive PWE");
402 break;
403 }
404
405 wpa_printf(MSG_DEBUG, "SAE: counter = %u", counter);
406 if (hmac_sha256_vector(addrs, sizeof(addrs), 2, addr, len,
407 pwd_seed) < 0)
408 break;
409 res = sae_test_pwd_seed_ffc(sae, pwd_seed, sae->tmp->pwe_ffc);
410 if (res < 0)
411 break;
412 if (res > 0) {
413 wpa_printf(MSG_DEBUG, "SAE: Use this PWE");
414 found = 1;
415 }
416 }
417
418 return found ? 0 : -1;
419}
420
421
422static int sae_derive_commit_element_ecc(struct sae_data *sae,
423 struct crypto_bignum *mask)
424{
425 /* COMMIT-ELEMENT = inverse(scalar-op(mask, PWE)) */
426 if (!sae->tmp->own_commit_element_ecc) {
427 sae->tmp->own_commit_element_ecc =
428 crypto_ec_point_init(sae->tmp->ec);
429 if (!sae->tmp->own_commit_element_ecc)
430 return -1;
431 }
432
433 if (crypto_ec_point_mul(sae->tmp->ec, sae->tmp->pwe_ecc, mask,
434 sae->tmp->own_commit_element_ecc) < 0 ||
435 crypto_ec_point_invert(sae->tmp->ec,
436 sae->tmp->own_commit_element_ecc) < 0) {
437 wpa_printf(MSG_DEBUG, "SAE: Could not compute commit-element");
438 return -1;
439 }
440
441 return 0;
442}
443
444
445static int sae_derive_commit_element_ffc(struct sae_data *sae,
446 struct crypto_bignum *mask)
447{
448 /* COMMIT-ELEMENT = inverse(scalar-op(mask, PWE)) */
449 if (!sae->tmp->own_commit_element_ffc) {
450 sae->tmp->own_commit_element_ffc = crypto_bignum_init();
451 if (!sae->tmp->own_commit_element_ffc)
452 return -1;
453 }
454
455 if (crypto_bignum_exptmod(sae->tmp->pwe_ffc, mask, sae->tmp->prime,
456 sae->tmp->own_commit_element_ffc) < 0 ||
457 crypto_bignum_inverse(sae->tmp->own_commit_element_ffc,
458 sae->tmp->prime,
459 sae->tmp->own_commit_element_ffc) < 0) {
460 wpa_printf(MSG_DEBUG, "SAE: Could not compute commit-element");
461 return -1;
462 }
463
464 return 0;
465}
466
467
468static int sae_derive_commit(struct sae_data *sae)
469{
470 struct crypto_bignum *mask;
471 int ret = -1;
472
473 mask = sae_get_rand_and_mask(sae);
474 if (mask == NULL) {
475 wpa_printf(MSG_DEBUG, "SAE: Could not get rand/mask");
476 return -1;
477 }
478
479 /* commit-scalar = (rand + mask) modulo r */
480 if (!sae->tmp->own_commit_scalar) {
481 sae->tmp->own_commit_scalar = crypto_bignum_init();
482 if (!sae->tmp->own_commit_scalar)
483 goto fail;
484 }
485 crypto_bignum_add(sae->tmp->sae_rand, mask,
486 sae->tmp->own_commit_scalar);
487 crypto_bignum_mod(sae->tmp->own_commit_scalar, sae->tmp->order,
488 sae->tmp->own_commit_scalar);
489
490 if (sae->tmp->ec && sae_derive_commit_element_ecc(sae, mask) < 0)
491 goto fail;
492 if (sae->tmp->dh && sae_derive_commit_element_ffc(sae, mask) < 0)
493 goto fail;
494
495 ret = 0;
496fail:
497 crypto_bignum_deinit(mask, 1);
498 return ret;
499}
500
501
502int sae_prepare_commit(const u8 *addr1, const u8 *addr2,
503 const u8 *password, size_t password_len,
504 struct sae_data *sae)
505{
506 if (sae->tmp->ec && sae_derive_pwe_ecc(sae, addr1, addr2, password,
507 password_len) < 0)
508 return -1;
509 if (sae->tmp->dh && sae_derive_pwe_ffc(sae, addr1, addr2, password,
510 password_len) < 0)
511 return -1;
512 if (sae_derive_commit(sae) < 0)
513 return -1;
514 return 0;
515}
516
517
518static int sae_derive_k_ecc(struct sae_data *sae, u8 *k)
519{
520 struct crypto_ec_point *K;
521 int ret = -1;
522
523 K = crypto_ec_point_init(sae->tmp->ec);
524 if (K == NULL)
525 goto fail;
526
527 /*
528 * K = scalar-op(rand, (elem-op(scalar-op(peer-commit-scalar, PWE),
529 * PEER-COMMIT-ELEMENT)))
530 * If K is identity element (point-at-infinity), reject
531 * k = F(K) (= x coordinate)
532 */
533
534 if (crypto_ec_point_mul(sae->tmp->ec, sae->tmp->pwe_ecc,
535 sae->peer_commit_scalar, K) < 0 ||
536 crypto_ec_point_add(sae->tmp->ec, K,
537 sae->tmp->peer_commit_element_ecc, K) < 0 ||
538 crypto_ec_point_mul(sae->tmp->ec, K, sae->tmp->sae_rand, K) < 0 ||
539 crypto_ec_point_is_at_infinity(sae->tmp->ec, K) ||
540 crypto_ec_point_to_bin(sae->tmp->ec, K, k, NULL) < 0) {
541 wpa_printf(MSG_DEBUG, "SAE: Failed to calculate K and k");
542 goto fail;
543 }
544
545 wpa_hexdump_key(MSG_DEBUG, "SAE: k", k, sae->tmp->prime_len);
546
547 ret = 0;
548fail:
549 crypto_ec_point_deinit(K, 1);
550 return ret;
551}
552
553
554static int sae_derive_k_ffc(struct sae_data *sae, u8 *k)
555{
556 struct crypto_bignum *K;
557 int ret = -1;
558
559 K = crypto_bignum_init();
560 if (K == NULL)
561 goto fail;
562
563 /*
564 * K = scalar-op(rand, (elem-op(scalar-op(peer-commit-scalar, PWE),
565 * PEER-COMMIT-ELEMENT)))
566 * If K is identity element (one), reject.
567 * k = F(K) (= x coordinate)
568 */
569
570 if (crypto_bignum_exptmod(sae->tmp->pwe_ffc, sae->peer_commit_scalar,
571 sae->tmp->prime, K) < 0 ||
572 crypto_bignum_mulmod(K, sae->tmp->peer_commit_element_ffc,
573 sae->tmp->prime, K) < 0 ||
574 crypto_bignum_exptmod(K, sae->tmp->sae_rand, sae->tmp->prime, K) < 0
575 ||
576 crypto_bignum_is_one(K) ||
577 crypto_bignum_to_bin(K, k, SAE_MAX_PRIME_LEN, sae->tmp->prime_len) <
578 0) {
579 wpa_printf(MSG_DEBUG, "SAE: Failed to calculate K and k");
580 goto fail;
581 }
582
583 wpa_hexdump_key(MSG_DEBUG, "SAE: k", k, sae->tmp->prime_len);
584
585 ret = 0;
586fail:
587 crypto_bignum_deinit(K, 1);
588 return ret;
589}
590
591
592static int sae_derive_keys(struct sae_data *sae, const u8 *k)
593{
594 u8 null_key[SAE_KEYSEED_KEY_LEN], val[SAE_MAX_PRIME_LEN];
595 u8 keyseed[SHA256_MAC_LEN];
596 u8 keys[SAE_KCK_LEN + SAE_PMK_LEN];
597 struct crypto_bignum *tmp;
598 int ret = -1;
599
600 tmp = crypto_bignum_init();
601 if (tmp == NULL)
602 goto fail;
603
604 /* keyseed = H(<0>32, k)
605 * KCK || PMK = KDF-512(keyseed, "SAE KCK and PMK",
606 * (commit-scalar + peer-commit-scalar) modulo r)
607 * PMKID = L((commit-scalar + peer-commit-scalar) modulo r, 0, 128)
608 */
609
610 os_memset(null_key, 0, sizeof(null_key));
611 hmac_sha256(null_key, sizeof(null_key), k, sae->tmp->prime_len,
612 keyseed);
613 wpa_hexdump_key(MSG_DEBUG, "SAE: keyseed", keyseed, sizeof(keyseed));
614
615 crypto_bignum_add(sae->tmp->own_commit_scalar, sae->peer_commit_scalar,
616 tmp);
617 crypto_bignum_mod(tmp, sae->tmp->order, tmp);
618 crypto_bignum_to_bin(tmp, val, sizeof(val), sae->tmp->prime_len);
619 wpa_hexdump(MSG_DEBUG, "SAE: PMKID", val, SAE_PMKID_LEN);
620 sha256_prf(keyseed, sizeof(keyseed), "SAE KCK and PMK",
621 val, sae->tmp->prime_len, keys, sizeof(keys));
622 os_memcpy(sae->tmp->kck, keys, SAE_KCK_LEN);
623 os_memcpy(sae->pmk, keys + SAE_KCK_LEN, SAE_PMK_LEN);
624 wpa_hexdump_key(MSG_DEBUG, "SAE: KCK", sae->tmp->kck, SAE_KCK_LEN);
625 wpa_hexdump_key(MSG_DEBUG, "SAE: PMK", sae->pmk, SAE_PMK_LEN);
626
627 ret = 0;
628fail:
629 crypto_bignum_deinit(tmp, 0);
630 return ret;
631}
632
633
634int sae_process_commit(struct sae_data *sae)
635{
636 u8 k[SAE_MAX_PRIME_LEN];
637 if ((sae->tmp->ec && sae_derive_k_ecc(sae, k) < 0) ||
638 (sae->tmp->dh && sae_derive_k_ffc(sae, k) < 0) ||
639 sae_derive_keys(sae, k) < 0)
640 return -1;
641 return 0;
642}
643
644
645void sae_write_commit(struct sae_data *sae, struct wpabuf *buf,
646 const struct wpabuf *token)
647{
648 u8 *pos;
649 wpabuf_put_le16(buf, sae->group); /* Finite Cyclic Group */
650 if (token)
651 wpabuf_put_buf(buf, token);
652 pos = wpabuf_put(buf, sae->tmp->prime_len);
653 crypto_bignum_to_bin(sae->tmp->own_commit_scalar, pos,
654 sae->tmp->prime_len, sae->tmp->prime_len);
655 wpa_hexdump(MSG_DEBUG, "SAE: own commit-scalar",
656 pos, sae->tmp->prime_len);
657 if (sae->tmp->ec) {
658 pos = wpabuf_put(buf, 2 * sae->tmp->prime_len);
659 crypto_ec_point_to_bin(sae->tmp->ec,
660 sae->tmp->own_commit_element_ecc,
661 pos, pos + sae->tmp->prime_len);
662 wpa_hexdump(MSG_DEBUG, "SAE: own commit-element(x)",
663 pos, sae->tmp->prime_len);
664 wpa_hexdump(MSG_DEBUG, "SAE: own commit-element(y)",
665 pos + sae->tmp->prime_len, sae->tmp->prime_len);
666 } else {
667 pos = wpabuf_put(buf, sae->tmp->prime_len);
668 crypto_bignum_to_bin(sae->tmp->own_commit_element_ffc, pos,
669 sae->tmp->prime_len, sae->tmp->prime_len);
670 wpa_hexdump(MSG_DEBUG, "SAE: own commit-element",
671 pos, sae->tmp->prime_len);
672 }
673}
674
675
676static u16 sae_group_allowed(struct sae_data *sae, int *allowed_groups,
677 u16 group)
678{
679 if (allowed_groups) {
680 int i;
681 for (i = 0; allowed_groups[i] > 0; i++) {
682 if (allowed_groups[i] == group)
683 break;
684 }
685 if (allowed_groups[i] != group) {
686 wpa_printf(MSG_DEBUG, "SAE: Proposed group %u not "
687 "enabled in the current configuration",
688 group);
689 return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
690 }
691 }
692
693 if (sae->state == SAE_COMMITTED && group != sae->group) {
694 wpa_printf(MSG_DEBUG, "SAE: Do not allow group to be changed");
695 return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
696 }
697
698 if (group != sae->group && sae_set_group(sae, group) < 0) {
699 wpa_printf(MSG_DEBUG, "SAE: Unsupported Finite Cyclic Group %u",
700 group);
701 return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
702 }
703
704 if (sae->tmp == NULL) {
705 wpa_printf(MSG_DEBUG, "SAE: Group information not yet initialized");
706 return WLAN_STATUS_UNSPECIFIED_FAILURE;
707 }
708
709 if (sae->tmp->dh && !allowed_groups) {
710 wpa_printf(MSG_DEBUG, "SAE: Do not allow FFC group %u without "
711 "explicit configuration enabling it", group);
712 return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
713 }
714
715 return WLAN_STATUS_SUCCESS;
716}
717
718
719static void sae_parse_commit_token(struct sae_data *sae, const u8 **pos,
720 const u8 *end, const u8 **token,
721 size_t *token_len)
722{
723 if (*pos + (sae->tmp->ec ? 3 : 2) * sae->tmp->prime_len < end) {
724 size_t tlen = end - (*pos + (sae->tmp->ec ? 3 : 2) *
725 sae->tmp->prime_len);
726 wpa_hexdump(MSG_DEBUG, "SAE: Anti-Clogging Token", *pos, tlen);
727 if (token)
728 *token = *pos;
729 if (token_len)
730 *token_len = tlen;
731 *pos += tlen;
732 } else {
733 if (token)
734 *token = NULL;
735 if (token_len)
736 *token_len = 0;
737 }
738}
739
740
741static u16 sae_parse_commit_scalar(struct sae_data *sae, const u8 **pos,
742 const u8 *end)
743{
744 struct crypto_bignum *peer_scalar;
745
746 if (*pos + sae->tmp->prime_len > end) {
747 wpa_printf(MSG_DEBUG, "SAE: Not enough data for scalar");
748 return WLAN_STATUS_UNSPECIFIED_FAILURE;
749 }
750
751 peer_scalar = crypto_bignum_init_set(*pos, sae->tmp->prime_len);
752 if (peer_scalar == NULL)
753 return WLAN_STATUS_UNSPECIFIED_FAILURE;
754
755 /*
756 * IEEE Std 802.11-2012, 11.3.8.6.1: If there is a protocol instance for
757 * the peer and it is in Authenticated state, the new Commit Message
758 * shall be dropped if the peer-scalar is identical to the one used in
759 * the existing protocol instance.
760 */
761 if (sae->state == SAE_ACCEPTED && sae->peer_commit_scalar &&
762 crypto_bignum_cmp(sae->peer_commit_scalar, peer_scalar) == 0) {
763 wpa_printf(MSG_DEBUG, "SAE: Do not accept re-use of previous "
764 "peer-commit-scalar");
765 crypto_bignum_deinit(peer_scalar, 0);
766 return WLAN_STATUS_UNSPECIFIED_FAILURE;
767 }
768
769 /* 0 < scalar < r */
770 if (crypto_bignum_is_zero(peer_scalar) ||
771 crypto_bignum_cmp(peer_scalar, sae->tmp->order) >= 0) {
772 wpa_printf(MSG_DEBUG, "SAE: Invalid peer scalar");
773 crypto_bignum_deinit(peer_scalar, 0);
774 return WLAN_STATUS_UNSPECIFIED_FAILURE;
775 }
776
777
778 crypto_bignum_deinit(sae->peer_commit_scalar, 0);
779 sae->peer_commit_scalar = peer_scalar;
780 wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-scalar",
781 *pos, sae->tmp->prime_len);
782 *pos += sae->tmp->prime_len;
783
784 return WLAN_STATUS_SUCCESS;
785}
786
787
788static u16 sae_parse_commit_element_ecc(struct sae_data *sae, const u8 *pos,
789 const u8 *end)
790{
791 u8 prime[SAE_MAX_ECC_PRIME_LEN];
792
793 if (pos + 2 * sae->tmp->prime_len > end) {
794 wpa_printf(MSG_DEBUG, "SAE: Not enough data for "
795 "commit-element");
796 return WLAN_STATUS_UNSPECIFIED_FAILURE;
797 }
798
799 if (crypto_bignum_to_bin(sae->tmp->prime, prime, sizeof(prime),
800 sae->tmp->prime_len) < 0)
801 return WLAN_STATUS_UNSPECIFIED_FAILURE;
802
803 /* element x and y coordinates < p */
804 if (os_memcmp(pos, prime, sae->tmp->prime_len) >= 0 ||
805 os_memcmp(pos + sae->tmp->prime_len, prime,
806 sae->tmp->prime_len) >= 0) {
807 wpa_printf(MSG_DEBUG, "SAE: Invalid coordinates in peer "
808 "element");
809 return WLAN_STATUS_UNSPECIFIED_FAILURE;
810 }
811
812 wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-element(x)",
813 pos, sae->tmp->prime_len);
814 wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-element(y)",
815 pos + sae->tmp->prime_len, sae->tmp->prime_len);
816
817 crypto_ec_point_deinit(sae->tmp->peer_commit_element_ecc, 0);
818 sae->tmp->peer_commit_element_ecc =
819 crypto_ec_point_from_bin(sae->tmp->ec, pos);
820 if (sae->tmp->peer_commit_element_ecc == NULL)
821 return WLAN_STATUS_UNSPECIFIED_FAILURE;
822
823 if (!crypto_ec_point_is_on_curve(sae->tmp->ec,
824 sae->tmp->peer_commit_element_ecc)) {
825 wpa_printf(MSG_DEBUG, "SAE: Peer element is not on curve");
826 return WLAN_STATUS_UNSPECIFIED_FAILURE;
827 }
828
829 return WLAN_STATUS_SUCCESS;
830}
831
832
833static u16 sae_parse_commit_element_ffc(struct sae_data *sae, const u8 *pos,
834 const u8 *end)
835{
836 struct crypto_bignum *res;
837
838 if (pos + sae->tmp->prime_len > end) {
839 wpa_printf(MSG_DEBUG, "SAE: Not enough data for "
840 "commit-element");
841 return WLAN_STATUS_UNSPECIFIED_FAILURE;
842 }
843 wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-element", pos,
844 sae->tmp->prime_len);
845
846 crypto_bignum_deinit(sae->tmp->peer_commit_element_ffc, 0);
847 sae->tmp->peer_commit_element_ffc =
848 crypto_bignum_init_set(pos, sae->tmp->prime_len);
849 if (sae->tmp->peer_commit_element_ffc == NULL)
850 return WLAN_STATUS_UNSPECIFIED_FAILURE;
851 if (crypto_bignum_is_zero(sae->tmp->peer_commit_element_ffc) ||
852 crypto_bignum_is_one(sae->tmp->peer_commit_element_ffc) ||
853 crypto_bignum_cmp(sae->tmp->peer_commit_element_ffc,
854 sae->tmp->prime) >= 0) {
855 wpa_printf(MSG_DEBUG, "SAE: Invalid peer element");
856 return WLAN_STATUS_UNSPECIFIED_FAILURE;
857 }
858
859 /* scalar-op(r, ELEMENT) = 1 modulo p */
860 res = crypto_bignum_init();
861 if (res == NULL ||
862 crypto_bignum_exptmod(sae->tmp->peer_commit_element_ffc,
863 sae->tmp->order, sae->tmp->prime, res) < 0 ||
864 !crypto_bignum_is_one(res)) {
865 wpa_printf(MSG_DEBUG, "SAE: Invalid peer element (scalar-op)");
866 crypto_bignum_deinit(res, 0);
867 return WLAN_STATUS_UNSPECIFIED_FAILURE;
868 }
869 crypto_bignum_deinit(res, 0);
870
871 return WLAN_STATUS_SUCCESS;
872}
873
874
875static u16 sae_parse_commit_element(struct sae_data *sae, const u8 *pos,
876 const u8 *end)
877{
878 if (sae->tmp->dh)
879 return sae_parse_commit_element_ffc(sae, pos, end);
880 return sae_parse_commit_element_ecc(sae, pos, end);
881}
882
883
884u16 sae_parse_commit(struct sae_data *sae, const u8 *data, size_t len,
885 const u8 **token, size_t *token_len, int *allowed_groups)
886{
887 const u8 *pos = data, *end = data + len;
888 u16 res;
889
890 /* Check Finite Cyclic Group */
891 if (pos + 2 > end)
892 return WLAN_STATUS_UNSPECIFIED_FAILURE;
893 res = sae_group_allowed(sae, allowed_groups, WPA_GET_LE16(pos));
894 if (res != WLAN_STATUS_SUCCESS)
895 return res;
896 pos += 2;
897
898 /* Optional Anti-Clogging Token */
899 sae_parse_commit_token(sae, &pos, end, token, token_len);
900
901 /* commit-scalar */
902 res = sae_parse_commit_scalar(sae, &pos, end);
903 if (res != WLAN_STATUS_SUCCESS)
904 return res;
905
906 /* commit-element */
907 return sae_parse_commit_element(sae, pos, end);
908}
909
910
911static void sae_cn_confirm(struct sae_data *sae, const u8 *sc,
912 const struct crypto_bignum *scalar1,
913 const u8 *element1, size_t element1_len,
914 const struct crypto_bignum *scalar2,
915 const u8 *element2, size_t element2_len,
916 u8 *confirm)
917{
918 const u8 *addr[5];
919 size_t len[5];
920 u8 scalar_b1[SAE_MAX_PRIME_LEN], scalar_b2[SAE_MAX_PRIME_LEN];
921
922 /* Confirm
923 * CN(key, X, Y, Z, ...) =
924 * HMAC-SHA256(key, D2OS(X) || D2OS(Y) || D2OS(Z) | ...)
925 * confirm = CN(KCK, send-confirm, commit-scalar, COMMIT-ELEMENT,
926 * peer-commit-scalar, PEER-COMMIT-ELEMENT)
927 * verifier = CN(KCK, peer-send-confirm, peer-commit-scalar,
928 * PEER-COMMIT-ELEMENT, commit-scalar, COMMIT-ELEMENT)
929 */
930 addr[0] = sc;
931 len[0] = 2;
932 crypto_bignum_to_bin(scalar1, scalar_b1, sizeof(scalar_b1),
933 sae->tmp->prime_len);
934 addr[1] = scalar_b1;
935 len[1] = sae->tmp->prime_len;
936 addr[2] = element1;
937 len[2] = element1_len;
938 crypto_bignum_to_bin(scalar2, scalar_b2, sizeof(scalar_b2),
939 sae->tmp->prime_len);
940 addr[3] = scalar_b2;
941 len[3] = sae->tmp->prime_len;
942 addr[4] = element2;
943 len[4] = element2_len;
944 hmac_sha256_vector(sae->tmp->kck, sizeof(sae->tmp->kck), 5, addr, len,
945 confirm);
946}
947
948
949static void sae_cn_confirm_ecc(struct sae_data *sae, const u8 *sc,
950 const struct crypto_bignum *scalar1,
951 const struct crypto_ec_point *element1,
952 const struct crypto_bignum *scalar2,
953 const struct crypto_ec_point *element2,
954 u8 *confirm)
955{
956 u8 element_b1[2 * SAE_MAX_ECC_PRIME_LEN];
957 u8 element_b2[2 * SAE_MAX_ECC_PRIME_LEN];
958
959 crypto_ec_point_to_bin(sae->tmp->ec, element1, element_b1,
960 element_b1 + sae->tmp->prime_len);
961 crypto_ec_point_to_bin(sae->tmp->ec, element2, element_b2,
962 element_b2 + sae->tmp->prime_len);
963
964 sae_cn_confirm(sae, sc, scalar1, element_b1, 2 * sae->tmp->prime_len,
965 scalar2, element_b2, 2 * sae->tmp->prime_len, confirm);
966}
967
968
969static void sae_cn_confirm_ffc(struct sae_data *sae, const u8 *sc,
970 const struct crypto_bignum *scalar1,
971 const struct crypto_bignum *element1,
972 const struct crypto_bignum *scalar2,
973 const struct crypto_bignum *element2,
974 u8 *confirm)
975{
976 u8 element_b1[SAE_MAX_PRIME_LEN];
977 u8 element_b2[SAE_MAX_PRIME_LEN];
978
979 crypto_bignum_to_bin(element1, element_b1, sizeof(element_b1),
980 sae->tmp->prime_len);
981 crypto_bignum_to_bin(element2, element_b2, sizeof(element_b2),
982 sae->tmp->prime_len);
983
984 sae_cn_confirm(sae, sc, scalar1, element_b1, sae->tmp->prime_len,
985 scalar2, element_b2, sae->tmp->prime_len, confirm);
986}
987
988
989void sae_write_confirm(struct sae_data *sae, struct wpabuf *buf)
990{
991 const u8 *sc;
992
993 /* Send-Confirm */
994 sc = wpabuf_put(buf, 0);
995 wpabuf_put_le16(buf, sae->send_confirm);
996 sae->send_confirm++;
997
998 if (sae->tmp->ec)
999 sae_cn_confirm_ecc(sae, sc, sae->tmp->own_commit_scalar,
1000 sae->tmp->own_commit_element_ecc,
1001 sae->peer_commit_scalar,
1002 sae->tmp->peer_commit_element_ecc,
1003 wpabuf_put(buf, SHA256_MAC_LEN));
1004 else
1005 sae_cn_confirm_ffc(sae, sc, sae->tmp->own_commit_scalar,
1006 sae->tmp->own_commit_element_ffc,
1007 sae->peer_commit_scalar,
1008 sae->tmp->peer_commit_element_ffc,
1009 wpabuf_put(buf, SHA256_MAC_LEN));
1010}
1011
1012
1013int sae_check_confirm(struct sae_data *sae, const u8 *data, size_t len)
1014{
1015 u8 verifier[SHA256_MAC_LEN];
1016
1017 if (len < 2 + SHA256_MAC_LEN) {
1018 wpa_printf(MSG_DEBUG, "SAE: Too short confirm message");
1019 return -1;
1020 }
1021
1022 wpa_printf(MSG_DEBUG, "SAE: peer-send-confirm %u", WPA_GET_LE16(data));
1023
1024 if (sae->tmp->ec)
1025 sae_cn_confirm_ecc(sae, data, sae->peer_commit_scalar,
1026 sae->tmp->peer_commit_element_ecc,
1027 sae->tmp->own_commit_scalar,
1028 sae->tmp->own_commit_element_ecc,
1029 verifier);
1030 else
1031 sae_cn_confirm_ffc(sae, data, sae->peer_commit_scalar,
1032 sae->tmp->peer_commit_element_ffc,
1033 sae->tmp->own_commit_scalar,
1034 sae->tmp->own_commit_element_ffc,
1035 verifier);
1036
1037 if (os_memcmp(verifier, data + 2, SHA256_MAC_LEN) != 0) {
1038 wpa_printf(MSG_DEBUG, "SAE: Confirm mismatch");
1039 wpa_hexdump(MSG_DEBUG, "SAE: Received confirm",
1040 data + 2, SHA256_MAC_LEN);
1041 wpa_hexdump(MSG_DEBUG, "SAE: Calculated verifier",
1042 verifier, SHA256_MAC_LEN);
1043 return -1;
1044 }
1045
1046 return 0;
1047}