1 /*
2 * Simultaneous authentication of equals
3 * Copyright (c) 2012-2015, 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
sae_set_group(struct sae_data * sae,int group)20 int 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
sae_clear_temp_data(struct sae_data * sae)73 void 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 wpabuf_free(tmp->anti_clogging_token);
91 bin_clear_free(tmp, sizeof(*tmp));
92 sae->tmp = NULL;
93 }
94
95
sae_clear_data(struct sae_data * sae)96 void sae_clear_data(struct sae_data *sae)
97 {
98 if (sae == NULL)
99 return;
100 sae_clear_temp_data(sae);
101 crypto_bignum_deinit(sae->peer_commit_scalar, 0);
102 os_memset(sae, 0, sizeof(*sae));
103 }
104
105
buf_shift_right(u8 * buf,size_t len,size_t bits)106 static void buf_shift_right(u8 *buf, size_t len, size_t bits)
107 {
108 size_t i;
109 for (i = len - 1; i > 0; i--)
110 buf[i] = (buf[i - 1] << (8 - bits)) | (buf[i] >> bits);
111 buf[0] >>= bits;
112 }
113
114
sae_get_rand(struct sae_data * sae)115 static struct crypto_bignum * sae_get_rand(struct sae_data *sae)
116 {
117 u8 val[SAE_MAX_PRIME_LEN];
118 int iter = 0;
119 struct crypto_bignum *bn = NULL;
120 int order_len_bits = crypto_bignum_bits(sae->tmp->order);
121 size_t order_len = (order_len_bits + 7) / 8;
122
123 if (order_len > sizeof(val))
124 return NULL;
125
126 for (;;) {
127 if (iter++ > 100 || random_get_bytes(val, order_len) < 0)
128 return NULL;
129 if (order_len_bits % 8)
130 buf_shift_right(val, order_len, 8 - order_len_bits % 8);
131 bn = crypto_bignum_init_set(val, order_len);
132 if (bn == NULL)
133 return NULL;
134 if (crypto_bignum_is_zero(bn) ||
135 crypto_bignum_is_one(bn) ||
136 crypto_bignum_cmp(bn, sae->tmp->order) >= 0) {
137 crypto_bignum_deinit(bn, 0);
138 continue;
139 }
140 break;
141 }
142
143 os_memset(val, 0, order_len);
144 return bn;
145 }
146
147
sae_get_rand_and_mask(struct sae_data * sae)148 static struct crypto_bignum * sae_get_rand_and_mask(struct sae_data *sae)
149 {
150 crypto_bignum_deinit(sae->tmp->sae_rand, 1);
151 sae->tmp->sae_rand = sae_get_rand(sae);
152 if (sae->tmp->sae_rand == NULL)
153 return NULL;
154 return sae_get_rand(sae);
155 }
156
157
sae_pwd_seed_key(const u8 * addr1,const u8 * addr2,u8 * key)158 static void sae_pwd_seed_key(const u8 *addr1, const u8 *addr2, u8 *key)
159 {
160 wpa_printf(MSG_DEBUG, "SAE: PWE derivation - addr1=" MACSTR
161 " addr2=" MACSTR, MAC2STR(addr1), MAC2STR(addr2));
162 if (os_memcmp(addr1, addr2, ETH_ALEN) > 0) {
163 os_memcpy(key, addr1, ETH_ALEN);
164 os_memcpy(key + ETH_ALEN, addr2, ETH_ALEN);
165 } else {
166 os_memcpy(key, addr2, ETH_ALEN);
167 os_memcpy(key + ETH_ALEN, addr1, ETH_ALEN);
168 }
169 }
170
171
172 static struct crypto_bignum *
get_rand_1_to_p_1(const u8 * prime,size_t prime_len,size_t prime_bits,int * r_odd)173 get_rand_1_to_p_1(const u8 *prime, size_t prime_len, size_t prime_bits,
174 int *r_odd)
175 {
176 for (;;) {
177 struct crypto_bignum *r;
178 u8 tmp[SAE_MAX_ECC_PRIME_LEN];
179
180 if (random_get_bytes(tmp, prime_len) < 0)
181 break;
182 if (prime_bits % 8)
183 buf_shift_right(tmp, prime_len, 8 - prime_bits % 8);
184 if (os_memcmp(tmp, prime, prime_len) >= 0)
185 continue;
186 r = crypto_bignum_init_set(tmp, prime_len);
187 if (!r)
188 break;
189 if (crypto_bignum_is_zero(r)) {
190 crypto_bignum_deinit(r, 0);
191 continue;
192 }
193
194 *r_odd = tmp[prime_len - 1] & 0x01;
195 return r;
196 }
197
198 return NULL;
199 }
200
201
is_quadratic_residue_blind(struct sae_data * sae,const u8 * prime,size_t bits,const struct crypto_bignum * qr,const struct crypto_bignum * qnr,const struct crypto_bignum * y_sqr)202 static int is_quadratic_residue_blind(struct sae_data *sae,
203 const u8 *prime, size_t bits,
204 const struct crypto_bignum *qr,
205 const struct crypto_bignum *qnr,
206 const struct crypto_bignum *y_sqr)
207 {
208 struct crypto_bignum *r, *num;
209 int r_odd, check, res = -1;
210
211 /*
212 * Use the blinding technique to mask y_sqr while determining
213 * whether it is a quadratic residue modulo p to avoid leaking
214 * timing information while determining the Legendre symbol.
215 *
216 * v = y_sqr
217 * r = a random number between 1 and p-1, inclusive
218 * num = (v * r * r) modulo p
219 */
220 r = get_rand_1_to_p_1(prime, sae->tmp->prime_len, bits, &r_odd);
221 if (!r)
222 return -1;
223
224 num = crypto_bignum_init();
225 if (!num ||
226 crypto_bignum_mulmod(y_sqr, r, sae->tmp->prime, num) < 0 ||
227 crypto_bignum_mulmod(num, r, sae->tmp->prime, num) < 0)
228 goto fail;
229
230 if (r_odd) {
231 /*
232 * num = (num * qr) module p
233 * LGR(num, p) = 1 ==> quadratic residue
234 */
235 if (crypto_bignum_mulmod(num, qr, sae->tmp->prime, num) < 0)
236 goto fail;
237 check = 1;
238 } else {
239 /*
240 * num = (num * qnr) module p
241 * LGR(num, p) = -1 ==> quadratic residue
242 */
243 if (crypto_bignum_mulmod(num, qnr, sae->tmp->prime, num) < 0)
244 goto fail;
245 check = -1;
246 }
247
248 res = crypto_bignum_legendre(num, sae->tmp->prime);
249 if (res == -2) {
250 res = -1;
251 goto fail;
252 }
253 res = res == check;
254 fail:
255 crypto_bignum_deinit(num, 1);
256 crypto_bignum_deinit(r, 1);
257 return res;
258 }
259
260
sae_test_pwd_seed_ecc(struct sae_data * sae,const u8 * pwd_seed,const u8 * prime,const struct crypto_bignum * qr,const struct crypto_bignum * qnr,struct crypto_bignum ** ret_x_cand)261 static int sae_test_pwd_seed_ecc(struct sae_data *sae, const u8 *pwd_seed,
262 const u8 *prime,
263 const struct crypto_bignum *qr,
264 const struct crypto_bignum *qnr,
265 struct crypto_bignum **ret_x_cand)
266 {
267 u8 pwd_value[SAE_MAX_ECC_PRIME_LEN];
268 struct crypto_bignum *y_sqr, *x_cand;
269 int res;
270 size_t bits;
271
272 *ret_x_cand = NULL;
273
274 wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-seed", pwd_seed, SHA256_MAC_LEN);
275
276 /* pwd-value = KDF-z(pwd-seed, "SAE Hunting and Pecking", p) */
277 bits = crypto_ec_prime_len_bits(sae->tmp->ec);
278 sha256_prf_bits(pwd_seed, SHA256_MAC_LEN, "SAE Hunting and Pecking",
279 prime, sae->tmp->prime_len, pwd_value, bits);
280 if (bits % 8)
281 buf_shift_right(pwd_value, sizeof(pwd_value), 8 - bits % 8);
282 wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value",
283 pwd_value, sae->tmp->prime_len);
284
285 if (os_memcmp(pwd_value, prime, sae->tmp->prime_len) >= 0)
286 return 0;
287
288 x_cand = crypto_bignum_init_set(pwd_value, sae->tmp->prime_len);
289 if (!x_cand)
290 return -1;
291 y_sqr = crypto_ec_point_compute_y_sqr(sae->tmp->ec, x_cand);
292 if (!y_sqr) {
293 crypto_bignum_deinit(x_cand, 1);
294 return -1;
295 }
296
297 res = is_quadratic_residue_blind(sae, prime, bits, qr, qnr, y_sqr);
298 crypto_bignum_deinit(y_sqr, 1);
299 if (res <= 0) {
300 crypto_bignum_deinit(x_cand, 1);
301 return res;
302 }
303
304 *ret_x_cand = x_cand;
305 return 1;
306 }
307
308
sae_test_pwd_seed_ffc(struct sae_data * sae,const u8 * pwd_seed,struct crypto_bignum * pwe)309 static int sae_test_pwd_seed_ffc(struct sae_data *sae, const u8 *pwd_seed,
310 struct crypto_bignum *pwe)
311 {
312 u8 pwd_value[SAE_MAX_PRIME_LEN];
313 size_t bits = sae->tmp->prime_len * 8;
314 u8 exp[1];
315 struct crypto_bignum *a, *b;
316 int res;
317
318 wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-seed", pwd_seed, SHA256_MAC_LEN);
319
320 /* pwd-value = KDF-z(pwd-seed, "SAE Hunting and Pecking", p) */
321 sha256_prf_bits(pwd_seed, SHA256_MAC_LEN, "SAE Hunting and Pecking",
322 sae->tmp->dh->prime, sae->tmp->prime_len, pwd_value,
323 bits);
324 if (bits % 8)
325 buf_shift_right(pwd_value, sizeof(pwd_value), 8 - bits % 8);
326 wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value", pwd_value,
327 sae->tmp->prime_len);
328
329 if (os_memcmp(pwd_value, sae->tmp->dh->prime, sae->tmp->prime_len) >= 0)
330 {
331 wpa_printf(MSG_DEBUG, "SAE: pwd-value >= p");
332 return 0;
333 }
334
335 /* PWE = pwd-value^((p-1)/r) modulo p */
336
337 a = crypto_bignum_init_set(pwd_value, sae->tmp->prime_len);
338
339 if (sae->tmp->dh->safe_prime) {
340 /*
341 * r = (p-1)/2 for the group used here, so this becomes:
342 * PWE = pwd-value^2 modulo p
343 */
344 exp[0] = 2;
345 b = crypto_bignum_init_set(exp, sizeof(exp));
346 } else {
347 /* Calculate exponent: (p-1)/r */
348 exp[0] = 1;
349 b = crypto_bignum_init_set(exp, sizeof(exp));
350 if (b == NULL ||
351 crypto_bignum_sub(sae->tmp->prime, b, b) < 0 ||
352 crypto_bignum_div(b, sae->tmp->order, b) < 0) {
353 crypto_bignum_deinit(b, 0);
354 b = NULL;
355 }
356 }
357
358 if (a == NULL || b == NULL)
359 res = -1;
360 else
361 res = crypto_bignum_exptmod(a, b, sae->tmp->prime, pwe);
362
363 crypto_bignum_deinit(a, 0);
364 crypto_bignum_deinit(b, 0);
365
366 if (res < 0) {
367 wpa_printf(MSG_DEBUG, "SAE: Failed to calculate PWE");
368 return -1;
369 }
370
371 /* if (PWE > 1) --> found */
372 if (crypto_bignum_is_zero(pwe) || crypto_bignum_is_one(pwe)) {
373 wpa_printf(MSG_DEBUG, "SAE: PWE <= 1");
374 return 0;
375 }
376
377 wpa_printf(MSG_DEBUG, "SAE: PWE found");
378 return 1;
379 }
380
381
get_random_qr_qnr(const u8 * prime,size_t prime_len,const struct crypto_bignum * prime_bn,size_t prime_bits,struct crypto_bignum ** qr,struct crypto_bignum ** qnr)382 static int get_random_qr_qnr(const u8 *prime, size_t prime_len,
383 const struct crypto_bignum *prime_bn,
384 size_t prime_bits, struct crypto_bignum **qr,
385 struct crypto_bignum **qnr)
386 {
387 *qr = NULL;
388 *qnr = NULL;
389
390 while (!(*qr) || !(*qnr)) {
391 u8 tmp[SAE_MAX_ECC_PRIME_LEN];
392 struct crypto_bignum *q;
393 int res;
394
395 if (random_get_bytes(tmp, prime_len) < 0)
396 break;
397 if (prime_bits % 8)
398 buf_shift_right(tmp, prime_len, 8 - prime_bits % 8);
399 if (os_memcmp(tmp, prime, prime_len) >= 0)
400 continue;
401 q = crypto_bignum_init_set(tmp, prime_len);
402 if (!q)
403 break;
404 res = crypto_bignum_legendre(q, prime_bn);
405
406 if (res == 1 && !(*qr))
407 *qr = q;
408 else if (res == -1 && !(*qnr))
409 *qnr = q;
410 else
411 crypto_bignum_deinit(q, 0);
412 }
413
414 return (*qr && *qnr) ? 0 : -1;
415 }
416
417
sae_derive_pwe_ecc(struct sae_data * sae,const u8 * addr1,const u8 * addr2,const u8 * password,size_t password_len)418 static int sae_derive_pwe_ecc(struct sae_data *sae, const u8 *addr1,
419 const u8 *addr2, const u8 *password,
420 size_t password_len)
421 {
422 u8 counter, k = 40;
423 u8 addrs[2 * ETH_ALEN];
424 const u8 *addr[2];
425 size_t len[2];
426 u8 dummy_password[32];
427 size_t dummy_password_len;
428 int pwd_seed_odd = 0;
429 u8 prime[SAE_MAX_ECC_PRIME_LEN];
430 size_t prime_len;
431 struct crypto_bignum *x = NULL, *qr, *qnr;
432 size_t bits;
433 int res;
434
435 dummy_password_len = password_len;
436 if (dummy_password_len > sizeof(dummy_password))
437 dummy_password_len = sizeof(dummy_password);
438 if (random_get_bytes(dummy_password, dummy_password_len) < 0)
439 return -1;
440
441 prime_len = sae->tmp->prime_len;
442 if (crypto_bignum_to_bin(sae->tmp->prime, prime, sizeof(prime),
443 prime_len) < 0)
444 return -1;
445 bits = crypto_ec_prime_len_bits(sae->tmp->ec);
446
447 /*
448 * Create a random quadratic residue (qr) and quadratic non-residue
449 * (qnr) modulo p for blinding purposes during the loop.
450 */
451 if (get_random_qr_qnr(prime, prime_len, sae->tmp->prime, bits,
452 &qr, &qnr) < 0)
453 return -1;
454
455 wpa_hexdump_ascii_key(MSG_DEBUG, "SAE: password",
456 password, password_len);
457
458 /*
459 * H(salt, ikm) = HMAC-SHA256(salt, ikm)
460 * base = password
461 * pwd-seed = H(MAX(STA-A-MAC, STA-B-MAC) || MIN(STA-A-MAC, STA-B-MAC),
462 * base || counter)
463 */
464 sae_pwd_seed_key(addr1, addr2, addrs);
465
466 addr[0] = password;
467 len[0] = password_len;
468 addr[1] = &counter;
469 len[1] = sizeof(counter);
470
471 /*
472 * Continue for at least k iterations to protect against side-channel
473 * attacks that attempt to determine the number of iterations required
474 * in the loop.
475 */
476 for (counter = 1; counter <= k || !x; counter++) {
477 u8 pwd_seed[SHA256_MAC_LEN];
478 struct crypto_bignum *x_cand;
479
480 if (counter > 200) {
481 /* This should not happen in practice */
482 wpa_printf(MSG_DEBUG, "SAE: Failed to derive PWE");
483 break;
484 }
485
486 wpa_printf(MSG_DEBUG, "SAE: counter = %u", counter);
487 if (hmac_sha256_vector(addrs, sizeof(addrs), 2, addr, len,
488 pwd_seed) < 0)
489 break;
490
491 res = sae_test_pwd_seed_ecc(sae, pwd_seed,
492 prime, qr, qnr, &x_cand);
493 if (res < 0)
494 goto fail;
495 if (res > 0 && !x) {
496 wpa_printf(MSG_DEBUG,
497 "SAE: Selected pwd-seed with counter %u",
498 counter);
499 x = x_cand;
500 pwd_seed_odd = pwd_seed[SHA256_MAC_LEN - 1] & 0x01;
501 os_memset(pwd_seed, 0, sizeof(pwd_seed));
502
503 /*
504 * Use a dummy password for the following rounds, if
505 * any.
506 */
507 addr[0] = dummy_password;
508 len[0] = dummy_password_len;
509 } else if (res > 0) {
510 crypto_bignum_deinit(x_cand, 1);
511 }
512 }
513
514 if (!x) {
515 wpa_printf(MSG_DEBUG, "SAE: Could not generate PWE");
516 res = -1;
517 goto fail;
518 }
519
520 if (!sae->tmp->pwe_ecc)
521 sae->tmp->pwe_ecc = crypto_ec_point_init(sae->tmp->ec);
522 if (!sae->tmp->pwe_ecc)
523 res = -1;
524 else
525 res = crypto_ec_point_solve_y_coord(sae->tmp->ec,
526 sae->tmp->pwe_ecc, x,
527 pwd_seed_odd);
528 crypto_bignum_deinit(x, 1);
529 if (res < 0) {
530 /*
531 * This should not happen since we already checked that there
532 * is a result.
533 */
534 wpa_printf(MSG_DEBUG, "SAE: Could not solve y");
535 }
536
537 fail:
538 crypto_bignum_deinit(qr, 0);
539 crypto_bignum_deinit(qnr, 0);
540
541 return res;
542 }
543
544
sae_derive_pwe_ffc(struct sae_data * sae,const u8 * addr1,const u8 * addr2,const u8 * password,size_t password_len)545 static int sae_derive_pwe_ffc(struct sae_data *sae, const u8 *addr1,
546 const u8 *addr2, const u8 *password,
547 size_t password_len)
548 {
549 u8 counter;
550 u8 addrs[2 * ETH_ALEN];
551 const u8 *addr[2];
552 size_t len[2];
553 int found = 0;
554
555 if (sae->tmp->pwe_ffc == NULL) {
556 sae->tmp->pwe_ffc = crypto_bignum_init();
557 if (sae->tmp->pwe_ffc == NULL)
558 return -1;
559 }
560
561 wpa_hexdump_ascii_key(MSG_DEBUG, "SAE: password",
562 password, password_len);
563
564 /*
565 * H(salt, ikm) = HMAC-SHA256(salt, ikm)
566 * pwd-seed = H(MAX(STA-A-MAC, STA-B-MAC) || MIN(STA-A-MAC, STA-B-MAC),
567 * password || counter)
568 */
569 sae_pwd_seed_key(addr1, addr2, addrs);
570
571 addr[0] = password;
572 len[0] = password_len;
573 addr[1] = &counter;
574 len[1] = sizeof(counter);
575
576 for (counter = 1; !found; counter++) {
577 u8 pwd_seed[SHA256_MAC_LEN];
578 int res;
579
580 if (counter > 200) {
581 /* This should not happen in practice */
582 wpa_printf(MSG_DEBUG, "SAE: Failed to derive PWE");
583 break;
584 }
585
586 wpa_printf(MSG_DEBUG, "SAE: counter = %u", counter);
587 if (hmac_sha256_vector(addrs, sizeof(addrs), 2, addr, len,
588 pwd_seed) < 0)
589 break;
590 res = sae_test_pwd_seed_ffc(sae, pwd_seed, sae->tmp->pwe_ffc);
591 if (res < 0)
592 break;
593 if (res > 0) {
594 wpa_printf(MSG_DEBUG, "SAE: Use this PWE");
595 found = 1;
596 }
597 }
598
599 return found ? 0 : -1;
600 }
601
602
sae_derive_commit_element_ecc(struct sae_data * sae,struct crypto_bignum * mask)603 static int sae_derive_commit_element_ecc(struct sae_data *sae,
604 struct crypto_bignum *mask)
605 {
606 /* COMMIT-ELEMENT = inverse(scalar-op(mask, PWE)) */
607 if (!sae->tmp->own_commit_element_ecc) {
608 sae->tmp->own_commit_element_ecc =
609 crypto_ec_point_init(sae->tmp->ec);
610 if (!sae->tmp->own_commit_element_ecc)
611 return -1;
612 }
613
614 if (crypto_ec_point_mul(sae->tmp->ec, sae->tmp->pwe_ecc, mask,
615 sae->tmp->own_commit_element_ecc) < 0 ||
616 crypto_ec_point_invert(sae->tmp->ec,
617 sae->tmp->own_commit_element_ecc) < 0) {
618 wpa_printf(MSG_DEBUG, "SAE: Could not compute commit-element");
619 return -1;
620 }
621
622 return 0;
623 }
624
625
sae_derive_commit_element_ffc(struct sae_data * sae,struct crypto_bignum * mask)626 static int sae_derive_commit_element_ffc(struct sae_data *sae,
627 struct crypto_bignum *mask)
628 {
629 /* COMMIT-ELEMENT = inverse(scalar-op(mask, PWE)) */
630 if (!sae->tmp->own_commit_element_ffc) {
631 sae->tmp->own_commit_element_ffc = crypto_bignum_init();
632 if (!sae->tmp->own_commit_element_ffc)
633 return -1;
634 }
635
636 if (crypto_bignum_exptmod(sae->tmp->pwe_ffc, mask, sae->tmp->prime,
637 sae->tmp->own_commit_element_ffc) < 0 ||
638 crypto_bignum_inverse(sae->tmp->own_commit_element_ffc,
639 sae->tmp->prime,
640 sae->tmp->own_commit_element_ffc) < 0) {
641 wpa_printf(MSG_DEBUG, "SAE: Could not compute commit-element");
642 return -1;
643 }
644
645 return 0;
646 }
647
648
sae_derive_commit(struct sae_data * sae)649 static int sae_derive_commit(struct sae_data *sae)
650 {
651 struct crypto_bignum *mask;
652 int ret = -1;
653 unsigned int counter = 0;
654
655 do {
656 counter++;
657 if (counter > 100) {
658 /*
659 * This cannot really happen in practice if the random
660 * number generator is working. Anyway, to avoid even a
661 * theoretical infinite loop, break out after 100
662 * attemps.
663 */
664 return -1;
665 }
666
667 mask = sae_get_rand_and_mask(sae);
668 if (mask == NULL) {
669 wpa_printf(MSG_DEBUG, "SAE: Could not get rand/mask");
670 return -1;
671 }
672
673 /* commit-scalar = (rand + mask) modulo r */
674 if (!sae->tmp->own_commit_scalar) {
675 sae->tmp->own_commit_scalar = crypto_bignum_init();
676 if (!sae->tmp->own_commit_scalar)
677 goto fail;
678 }
679 crypto_bignum_add(sae->tmp->sae_rand, mask,
680 sae->tmp->own_commit_scalar);
681 crypto_bignum_mod(sae->tmp->own_commit_scalar, sae->tmp->order,
682 sae->tmp->own_commit_scalar);
683 } while (crypto_bignum_is_zero(sae->tmp->own_commit_scalar) ||
684 crypto_bignum_is_one(sae->tmp->own_commit_scalar));
685
686 if ((sae->tmp->ec && sae_derive_commit_element_ecc(sae, mask) < 0) ||
687 (sae->tmp->dh && sae_derive_commit_element_ffc(sae, mask) < 0))
688 goto fail;
689
690 ret = 0;
691 fail:
692 crypto_bignum_deinit(mask, 1);
693 return ret;
694 }
695
696
sae_prepare_commit(const u8 * addr1,const u8 * addr2,const u8 * password,size_t password_len,struct sae_data * sae)697 int sae_prepare_commit(const u8 *addr1, const u8 *addr2,
698 const u8 *password, size_t password_len,
699 struct sae_data *sae)
700 {
701 if (sae->tmp == NULL ||
702 (sae->tmp->ec && sae_derive_pwe_ecc(sae, addr1, addr2, password,
703 password_len) < 0) ||
704 (sae->tmp->dh && sae_derive_pwe_ffc(sae, addr1, addr2, password,
705 password_len) < 0) ||
706 sae_derive_commit(sae) < 0)
707 return -1;
708 return 0;
709 }
710
711
sae_derive_k_ecc(struct sae_data * sae,u8 * k)712 static int sae_derive_k_ecc(struct sae_data *sae, u8 *k)
713 {
714 struct crypto_ec_point *K;
715 int ret = -1;
716
717 K = crypto_ec_point_init(sae->tmp->ec);
718 if (K == NULL)
719 goto fail;
720
721 /*
722 * K = scalar-op(rand, (elem-op(scalar-op(peer-commit-scalar, PWE),
723 * PEER-COMMIT-ELEMENT)))
724 * If K is identity element (point-at-infinity), reject
725 * k = F(K) (= x coordinate)
726 */
727
728 if (crypto_ec_point_mul(sae->tmp->ec, sae->tmp->pwe_ecc,
729 sae->peer_commit_scalar, K) < 0 ||
730 crypto_ec_point_add(sae->tmp->ec, K,
731 sae->tmp->peer_commit_element_ecc, K) < 0 ||
732 crypto_ec_point_mul(sae->tmp->ec, K, sae->tmp->sae_rand, K) < 0 ||
733 crypto_ec_point_is_at_infinity(sae->tmp->ec, K) ||
734 crypto_ec_point_to_bin(sae->tmp->ec, K, k, NULL) < 0) {
735 wpa_printf(MSG_DEBUG, "SAE: Failed to calculate K and k");
736 goto fail;
737 }
738
739 wpa_hexdump_key(MSG_DEBUG, "SAE: k", k, sae->tmp->prime_len);
740
741 ret = 0;
742 fail:
743 crypto_ec_point_deinit(K, 1);
744 return ret;
745 }
746
747
sae_derive_k_ffc(struct sae_data * sae,u8 * k)748 static int sae_derive_k_ffc(struct sae_data *sae, u8 *k)
749 {
750 struct crypto_bignum *K;
751 int ret = -1;
752
753 K = crypto_bignum_init();
754 if (K == NULL)
755 goto fail;
756
757 /*
758 * K = scalar-op(rand, (elem-op(scalar-op(peer-commit-scalar, PWE),
759 * PEER-COMMIT-ELEMENT)))
760 * If K is identity element (one), reject.
761 * k = F(K) (= x coordinate)
762 */
763
764 if (crypto_bignum_exptmod(sae->tmp->pwe_ffc, sae->peer_commit_scalar,
765 sae->tmp->prime, K) < 0 ||
766 crypto_bignum_mulmod(K, sae->tmp->peer_commit_element_ffc,
767 sae->tmp->prime, K) < 0 ||
768 crypto_bignum_exptmod(K, sae->tmp->sae_rand, sae->tmp->prime, K) < 0
769 ||
770 crypto_bignum_is_one(K) ||
771 crypto_bignum_to_bin(K, k, SAE_MAX_PRIME_LEN, sae->tmp->prime_len) <
772 0) {
773 wpa_printf(MSG_DEBUG, "SAE: Failed to calculate K and k");
774 goto fail;
775 }
776
777 wpa_hexdump_key(MSG_DEBUG, "SAE: k", k, sae->tmp->prime_len);
778
779 ret = 0;
780 fail:
781 crypto_bignum_deinit(K, 1);
782 return ret;
783 }
784
785
sae_derive_keys(struct sae_data * sae,const u8 * k)786 static int sae_derive_keys(struct sae_data *sae, const u8 *k)
787 {
788 u8 null_key[SAE_KEYSEED_KEY_LEN], val[SAE_MAX_PRIME_LEN];
789 u8 keyseed[SHA256_MAC_LEN];
790 u8 keys[SAE_KCK_LEN + SAE_PMK_LEN];
791 struct crypto_bignum *tmp;
792 int ret = -1;
793
794 tmp = crypto_bignum_init();
795 if (tmp == NULL)
796 goto fail;
797
798 /* keyseed = H(<0>32, k)
799 * KCK || PMK = KDF-512(keyseed, "SAE KCK and PMK",
800 * (commit-scalar + peer-commit-scalar) modulo r)
801 * PMKID = L((commit-scalar + peer-commit-scalar) modulo r, 0, 128)
802 */
803
804 os_memset(null_key, 0, sizeof(null_key));
805 hmac_sha256(null_key, sizeof(null_key), k, sae->tmp->prime_len,
806 keyseed);
807 wpa_hexdump_key(MSG_DEBUG, "SAE: keyseed", keyseed, sizeof(keyseed));
808
809 crypto_bignum_add(sae->tmp->own_commit_scalar, sae->peer_commit_scalar,
810 tmp);
811 crypto_bignum_mod(tmp, sae->tmp->order, tmp);
812 crypto_bignum_to_bin(tmp, val, sizeof(val), sae->tmp->prime_len);
813 wpa_hexdump(MSG_DEBUG, "SAE: PMKID", val, SAE_PMKID_LEN);
814 sha256_prf(keyseed, sizeof(keyseed), "SAE KCK and PMK",
815 val, sae->tmp->prime_len, keys, sizeof(keys));
816 os_memset(keyseed, 0, sizeof(keyseed));
817 os_memcpy(sae->tmp->kck, keys, SAE_KCK_LEN);
818 os_memcpy(sae->pmk, keys + SAE_KCK_LEN, SAE_PMK_LEN);
819 os_memset(keys, 0, sizeof(keys));
820 wpa_hexdump_key(MSG_DEBUG, "SAE: KCK", sae->tmp->kck, SAE_KCK_LEN);
821 wpa_hexdump_key(MSG_DEBUG, "SAE: PMK", sae->pmk, SAE_PMK_LEN);
822
823 ret = 0;
824 fail:
825 crypto_bignum_deinit(tmp, 0);
826 return ret;
827 }
828
829
sae_process_commit(struct sae_data * sae)830 int sae_process_commit(struct sae_data *sae)
831 {
832 u8 k[SAE_MAX_PRIME_LEN];
833 if (sae->tmp == NULL ||
834 (sae->tmp->ec && sae_derive_k_ecc(sae, k) < 0) ||
835 (sae->tmp->dh && sae_derive_k_ffc(sae, k) < 0) ||
836 sae_derive_keys(sae, k) < 0)
837 return -1;
838 return 0;
839 }
840
841
sae_write_commit(struct sae_data * sae,struct wpabuf * buf,const struct wpabuf * token)842 void sae_write_commit(struct sae_data *sae, struct wpabuf *buf,
843 const struct wpabuf *token)
844 {
845 u8 *pos;
846
847 if (sae->tmp == NULL)
848 return;
849
850 wpabuf_put_le16(buf, sae->group); /* Finite Cyclic Group */
851 if (token) {
852 wpabuf_put_buf(buf, token);
853 wpa_hexdump(MSG_DEBUG, "SAE: Anti-clogging token",
854 wpabuf_head(token), wpabuf_len(token));
855 }
856 pos = wpabuf_put(buf, sae->tmp->prime_len);
857 crypto_bignum_to_bin(sae->tmp->own_commit_scalar, pos,
858 sae->tmp->prime_len, sae->tmp->prime_len);
859 wpa_hexdump(MSG_DEBUG, "SAE: own commit-scalar",
860 pos, sae->tmp->prime_len);
861 if (sae->tmp->ec) {
862 pos = wpabuf_put(buf, 2 * sae->tmp->prime_len);
863 crypto_ec_point_to_bin(sae->tmp->ec,
864 sae->tmp->own_commit_element_ecc,
865 pos, pos + sae->tmp->prime_len);
866 wpa_hexdump(MSG_DEBUG, "SAE: own commit-element(x)",
867 pos, sae->tmp->prime_len);
868 wpa_hexdump(MSG_DEBUG, "SAE: own commit-element(y)",
869 pos + sae->tmp->prime_len, sae->tmp->prime_len);
870 } else {
871 pos = wpabuf_put(buf, sae->tmp->prime_len);
872 crypto_bignum_to_bin(sae->tmp->own_commit_element_ffc, pos,
873 sae->tmp->prime_len, sae->tmp->prime_len);
874 wpa_hexdump(MSG_DEBUG, "SAE: own commit-element",
875 pos, sae->tmp->prime_len);
876 }
877 }
878
879
sae_group_allowed(struct sae_data * sae,int * allowed_groups,u16 group)880 u16 sae_group_allowed(struct sae_data *sae, int *allowed_groups, u16 group)
881 {
882 if (allowed_groups) {
883 int i;
884 for (i = 0; allowed_groups[i] > 0; i++) {
885 if (allowed_groups[i] == group)
886 break;
887 }
888 if (allowed_groups[i] != group) {
889 wpa_printf(MSG_DEBUG, "SAE: Proposed group %u not "
890 "enabled in the current configuration",
891 group);
892 return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
893 }
894 }
895
896 if (sae->state == SAE_COMMITTED && group != sae->group) {
897 wpa_printf(MSG_DEBUG, "SAE: Do not allow group to be changed");
898 return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
899 }
900
901 if (group != sae->group && sae_set_group(sae, group) < 0) {
902 wpa_printf(MSG_DEBUG, "SAE: Unsupported Finite Cyclic Group %u",
903 group);
904 return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
905 }
906
907 if (sae->tmp == NULL) {
908 wpa_printf(MSG_DEBUG, "SAE: Group information not yet initialized");
909 return WLAN_STATUS_UNSPECIFIED_FAILURE;
910 }
911
912 if (sae->tmp->dh && !allowed_groups) {
913 wpa_printf(MSG_DEBUG, "SAE: Do not allow FFC group %u without "
914 "explicit configuration enabling it", group);
915 return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
916 }
917
918 return WLAN_STATUS_SUCCESS;
919 }
920
921
sae_parse_commit_token(struct sae_data * sae,const u8 ** pos,const u8 * end,const u8 ** token,size_t * token_len)922 static void sae_parse_commit_token(struct sae_data *sae, const u8 **pos,
923 const u8 *end, const u8 **token,
924 size_t *token_len)
925 {
926 if (*pos + (sae->tmp->ec ? 3 : 2) * sae->tmp->prime_len < end) {
927 size_t tlen = end - (*pos + (sae->tmp->ec ? 3 : 2) *
928 sae->tmp->prime_len);
929 wpa_hexdump(MSG_DEBUG, "SAE: Anti-Clogging Token", *pos, tlen);
930 if (token)
931 *token = *pos;
932 if (token_len)
933 *token_len = tlen;
934 *pos += tlen;
935 } else {
936 if (token)
937 *token = NULL;
938 if (token_len)
939 *token_len = 0;
940 }
941 }
942
943
sae_parse_commit_scalar(struct sae_data * sae,const u8 ** pos,const u8 * end)944 static u16 sae_parse_commit_scalar(struct sae_data *sae, const u8 **pos,
945 const u8 *end)
946 {
947 struct crypto_bignum *peer_scalar;
948
949 if (*pos + sae->tmp->prime_len > end) {
950 wpa_printf(MSG_DEBUG, "SAE: Not enough data for scalar");
951 return WLAN_STATUS_UNSPECIFIED_FAILURE;
952 }
953
954 peer_scalar = crypto_bignum_init_set(*pos, sae->tmp->prime_len);
955 if (peer_scalar == NULL)
956 return WLAN_STATUS_UNSPECIFIED_FAILURE;
957
958 /*
959 * IEEE Std 802.11-2012, 11.3.8.6.1: If there is a protocol instance for
960 * the peer and it is in Authenticated state, the new Commit Message
961 * shall be dropped if the peer-scalar is identical to the one used in
962 * the existing protocol instance.
963 */
964 if (sae->state == SAE_ACCEPTED && sae->peer_commit_scalar &&
965 crypto_bignum_cmp(sae->peer_commit_scalar, peer_scalar) == 0) {
966 wpa_printf(MSG_DEBUG, "SAE: Do not accept re-use of previous "
967 "peer-commit-scalar");
968 crypto_bignum_deinit(peer_scalar, 0);
969 return WLAN_STATUS_UNSPECIFIED_FAILURE;
970 }
971
972 /* 1 < scalar < r */
973 if (crypto_bignum_is_zero(peer_scalar) ||
974 crypto_bignum_is_one(peer_scalar) ||
975 crypto_bignum_cmp(peer_scalar, sae->tmp->order) >= 0) {
976 wpa_printf(MSG_DEBUG, "SAE: Invalid peer scalar");
977 crypto_bignum_deinit(peer_scalar, 0);
978 return WLAN_STATUS_UNSPECIFIED_FAILURE;
979 }
980
981
982 crypto_bignum_deinit(sae->peer_commit_scalar, 0);
983 sae->peer_commit_scalar = peer_scalar;
984 wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-scalar",
985 *pos, sae->tmp->prime_len);
986 *pos += sae->tmp->prime_len;
987
988 return WLAN_STATUS_SUCCESS;
989 }
990
991
sae_parse_commit_element_ecc(struct sae_data * sae,const u8 * pos,const u8 * end)992 static u16 sae_parse_commit_element_ecc(struct sae_data *sae, const u8 *pos,
993 const u8 *end)
994 {
995 u8 prime[SAE_MAX_ECC_PRIME_LEN];
996
997 if (pos + 2 * sae->tmp->prime_len > end) {
998 wpa_printf(MSG_DEBUG, "SAE: Not enough data for "
999 "commit-element");
1000 return WLAN_STATUS_UNSPECIFIED_FAILURE;
1001 }
1002
1003 if (crypto_bignum_to_bin(sae->tmp->prime, prime, sizeof(prime),
1004 sae->tmp->prime_len) < 0)
1005 return WLAN_STATUS_UNSPECIFIED_FAILURE;
1006
1007 /* element x and y coordinates < p */
1008 if (os_memcmp(pos, prime, sae->tmp->prime_len) >= 0 ||
1009 os_memcmp(pos + sae->tmp->prime_len, prime,
1010 sae->tmp->prime_len) >= 0) {
1011 wpa_printf(MSG_DEBUG, "SAE: Invalid coordinates in peer "
1012 "element");
1013 return WLAN_STATUS_UNSPECIFIED_FAILURE;
1014 }
1015
1016 wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-element(x)",
1017 pos, sae->tmp->prime_len);
1018 wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-element(y)",
1019 pos + sae->tmp->prime_len, sae->tmp->prime_len);
1020
1021 crypto_ec_point_deinit(sae->tmp->peer_commit_element_ecc, 0);
1022 sae->tmp->peer_commit_element_ecc =
1023 crypto_ec_point_from_bin(sae->tmp->ec, pos);
1024 if (sae->tmp->peer_commit_element_ecc == NULL)
1025 return WLAN_STATUS_UNSPECIFIED_FAILURE;
1026
1027 if (!crypto_ec_point_is_on_curve(sae->tmp->ec,
1028 sae->tmp->peer_commit_element_ecc)) {
1029 wpa_printf(MSG_DEBUG, "SAE: Peer element is not on curve");
1030 return WLAN_STATUS_UNSPECIFIED_FAILURE;
1031 }
1032
1033 return WLAN_STATUS_SUCCESS;
1034 }
1035
1036
sae_parse_commit_element_ffc(struct sae_data * sae,const u8 * pos,const u8 * end)1037 static u16 sae_parse_commit_element_ffc(struct sae_data *sae, const u8 *pos,
1038 const u8 *end)
1039 {
1040 struct crypto_bignum *res, *one;
1041 const u8 one_bin[1] = { 0x01 };
1042
1043 if (pos + sae->tmp->prime_len > end) {
1044 wpa_printf(MSG_DEBUG, "SAE: Not enough data for "
1045 "commit-element");
1046 return WLAN_STATUS_UNSPECIFIED_FAILURE;
1047 }
1048 wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-element", pos,
1049 sae->tmp->prime_len);
1050
1051 crypto_bignum_deinit(sae->tmp->peer_commit_element_ffc, 0);
1052 sae->tmp->peer_commit_element_ffc =
1053 crypto_bignum_init_set(pos, sae->tmp->prime_len);
1054 if (sae->tmp->peer_commit_element_ffc == NULL)
1055 return WLAN_STATUS_UNSPECIFIED_FAILURE;
1056 /* 1 < element < p - 1 */
1057 res = crypto_bignum_init();
1058 one = crypto_bignum_init_set(one_bin, sizeof(one_bin));
1059 if (!res || !one ||
1060 crypto_bignum_sub(sae->tmp->prime, one, res) ||
1061 crypto_bignum_is_zero(sae->tmp->peer_commit_element_ffc) ||
1062 crypto_bignum_is_one(sae->tmp->peer_commit_element_ffc) ||
1063 crypto_bignum_cmp(sae->tmp->peer_commit_element_ffc, res) >= 0) {
1064 crypto_bignum_deinit(res, 0);
1065 crypto_bignum_deinit(one, 0);
1066 wpa_printf(MSG_DEBUG, "SAE: Invalid peer element");
1067 return WLAN_STATUS_UNSPECIFIED_FAILURE;
1068 }
1069 crypto_bignum_deinit(one, 0);
1070
1071 /* scalar-op(r, ELEMENT) = 1 modulo p */
1072 if (crypto_bignum_exptmod(sae->tmp->peer_commit_element_ffc,
1073 sae->tmp->order, sae->tmp->prime, res) < 0 ||
1074 !crypto_bignum_is_one(res)) {
1075 wpa_printf(MSG_DEBUG, "SAE: Invalid peer element (scalar-op)");
1076 crypto_bignum_deinit(res, 0);
1077 return WLAN_STATUS_UNSPECIFIED_FAILURE;
1078 }
1079 crypto_bignum_deinit(res, 0);
1080
1081 return WLAN_STATUS_SUCCESS;
1082 }
1083
1084
sae_parse_commit_element(struct sae_data * sae,const u8 * pos,const u8 * end)1085 static u16 sae_parse_commit_element(struct sae_data *sae, const u8 *pos,
1086 const u8 *end)
1087 {
1088 if (sae->tmp->dh)
1089 return sae_parse_commit_element_ffc(sae, pos, end);
1090 return sae_parse_commit_element_ecc(sae, pos, end);
1091 }
1092
1093
sae_parse_commit(struct sae_data * sae,const u8 * data,size_t len,const u8 ** token,size_t * token_len,int * allowed_groups)1094 u16 sae_parse_commit(struct sae_data *sae, const u8 *data, size_t len,
1095 const u8 **token, size_t *token_len, int *allowed_groups)
1096 {
1097 const u8 *pos = data, *end = data + len;
1098 u16 res;
1099
1100 /* Check Finite Cyclic Group */
1101 if (pos + 2 > end)
1102 return WLAN_STATUS_UNSPECIFIED_FAILURE;
1103 res = sae_group_allowed(sae, allowed_groups, WPA_GET_LE16(pos));
1104 if (res != WLAN_STATUS_SUCCESS)
1105 return res;
1106 pos += 2;
1107
1108 /* Optional Anti-Clogging Token */
1109 sae_parse_commit_token(sae, &pos, end, token, token_len);
1110
1111 /* commit-scalar */
1112 res = sae_parse_commit_scalar(sae, &pos, end);
1113 if (res != WLAN_STATUS_SUCCESS)
1114 return res;
1115
1116 /* commit-element */
1117 res = sae_parse_commit_element(sae, pos, end);
1118 if (res != WLAN_STATUS_SUCCESS)
1119 return res;
1120
1121 /*
1122 * Check whether peer-commit-scalar and PEER-COMMIT-ELEMENT are same as
1123 * the values we sent which would be evidence of a reflection attack.
1124 */
1125 if (!sae->tmp->own_commit_scalar ||
1126 crypto_bignum_cmp(sae->tmp->own_commit_scalar,
1127 sae->peer_commit_scalar) != 0 ||
1128 (sae->tmp->dh &&
1129 (!sae->tmp->own_commit_element_ffc ||
1130 crypto_bignum_cmp(sae->tmp->own_commit_element_ffc,
1131 sae->tmp->peer_commit_element_ffc) != 0)) ||
1132 (sae->tmp->ec &&
1133 (!sae->tmp->own_commit_element_ecc ||
1134 crypto_ec_point_cmp(sae->tmp->ec,
1135 sae->tmp->own_commit_element_ecc,
1136 sae->tmp->peer_commit_element_ecc) != 0)))
1137 return WLAN_STATUS_SUCCESS; /* scalars/elements are different */
1138
1139 /*
1140 * This is a reflection attack - return special value to trigger caller
1141 * to silently discard the frame instead of replying with a specific
1142 * status code.
1143 */
1144 return SAE_SILENTLY_DISCARD;
1145 }
1146
1147
sae_cn_confirm(struct sae_data * sae,const u8 * sc,const struct crypto_bignum * scalar1,const u8 * element1,size_t element1_len,const struct crypto_bignum * scalar2,const u8 * element2,size_t element2_len,u8 * confirm)1148 static void sae_cn_confirm(struct sae_data *sae, const u8 *sc,
1149 const struct crypto_bignum *scalar1,
1150 const u8 *element1, size_t element1_len,
1151 const struct crypto_bignum *scalar2,
1152 const u8 *element2, size_t element2_len,
1153 u8 *confirm)
1154 {
1155 const u8 *addr[5];
1156 size_t len[5];
1157 u8 scalar_b1[SAE_MAX_PRIME_LEN], scalar_b2[SAE_MAX_PRIME_LEN];
1158
1159 /* Confirm
1160 * CN(key, X, Y, Z, ...) =
1161 * HMAC-SHA256(key, D2OS(X) || D2OS(Y) || D2OS(Z) | ...)
1162 * confirm = CN(KCK, send-confirm, commit-scalar, COMMIT-ELEMENT,
1163 * peer-commit-scalar, PEER-COMMIT-ELEMENT)
1164 * verifier = CN(KCK, peer-send-confirm, peer-commit-scalar,
1165 * PEER-COMMIT-ELEMENT, commit-scalar, COMMIT-ELEMENT)
1166 */
1167 addr[0] = sc;
1168 len[0] = 2;
1169 crypto_bignum_to_bin(scalar1, scalar_b1, sizeof(scalar_b1),
1170 sae->tmp->prime_len);
1171 addr[1] = scalar_b1;
1172 len[1] = sae->tmp->prime_len;
1173 addr[2] = element1;
1174 len[2] = element1_len;
1175 crypto_bignum_to_bin(scalar2, scalar_b2, sizeof(scalar_b2),
1176 sae->tmp->prime_len);
1177 addr[3] = scalar_b2;
1178 len[3] = sae->tmp->prime_len;
1179 addr[4] = element2;
1180 len[4] = element2_len;
1181 hmac_sha256_vector(sae->tmp->kck, sizeof(sae->tmp->kck), 5, addr, len,
1182 confirm);
1183 }
1184
1185
sae_cn_confirm_ecc(struct sae_data * sae,const u8 * sc,const struct crypto_bignum * scalar1,const struct crypto_ec_point * element1,const struct crypto_bignum * scalar2,const struct crypto_ec_point * element2,u8 * confirm)1186 static void sae_cn_confirm_ecc(struct sae_data *sae, const u8 *sc,
1187 const struct crypto_bignum *scalar1,
1188 const struct crypto_ec_point *element1,
1189 const struct crypto_bignum *scalar2,
1190 const struct crypto_ec_point *element2,
1191 u8 *confirm)
1192 {
1193 u8 element_b1[2 * SAE_MAX_ECC_PRIME_LEN];
1194 u8 element_b2[2 * SAE_MAX_ECC_PRIME_LEN];
1195
1196 crypto_ec_point_to_bin(sae->tmp->ec, element1, element_b1,
1197 element_b1 + sae->tmp->prime_len);
1198 crypto_ec_point_to_bin(sae->tmp->ec, element2, element_b2,
1199 element_b2 + sae->tmp->prime_len);
1200
1201 sae_cn_confirm(sae, sc, scalar1, element_b1, 2 * sae->tmp->prime_len,
1202 scalar2, element_b2, 2 * sae->tmp->prime_len, confirm);
1203 }
1204
1205
sae_cn_confirm_ffc(struct sae_data * sae,const u8 * sc,const struct crypto_bignum * scalar1,const struct crypto_bignum * element1,const struct crypto_bignum * scalar2,const struct crypto_bignum * element2,u8 * confirm)1206 static void sae_cn_confirm_ffc(struct sae_data *sae, const u8 *sc,
1207 const struct crypto_bignum *scalar1,
1208 const struct crypto_bignum *element1,
1209 const struct crypto_bignum *scalar2,
1210 const struct crypto_bignum *element2,
1211 u8 *confirm)
1212 {
1213 u8 element_b1[SAE_MAX_PRIME_LEN];
1214 u8 element_b2[SAE_MAX_PRIME_LEN];
1215
1216 crypto_bignum_to_bin(element1, element_b1, sizeof(element_b1),
1217 sae->tmp->prime_len);
1218 crypto_bignum_to_bin(element2, element_b2, sizeof(element_b2),
1219 sae->tmp->prime_len);
1220
1221 sae_cn_confirm(sae, sc, scalar1, element_b1, sae->tmp->prime_len,
1222 scalar2, element_b2, sae->tmp->prime_len, confirm);
1223 }
1224
1225
sae_write_confirm(struct sae_data * sae,struct wpabuf * buf)1226 void sae_write_confirm(struct sae_data *sae, struct wpabuf *buf)
1227 {
1228 const u8 *sc;
1229
1230 if (sae->tmp == NULL)
1231 return;
1232
1233 /* Send-Confirm */
1234 sc = wpabuf_put(buf, 0);
1235 wpabuf_put_le16(buf, sae->send_confirm);
1236 sae->send_confirm++;
1237
1238 if (sae->tmp->ec)
1239 sae_cn_confirm_ecc(sae, sc, sae->tmp->own_commit_scalar,
1240 sae->tmp->own_commit_element_ecc,
1241 sae->peer_commit_scalar,
1242 sae->tmp->peer_commit_element_ecc,
1243 wpabuf_put(buf, SHA256_MAC_LEN));
1244 else
1245 sae_cn_confirm_ffc(sae, sc, sae->tmp->own_commit_scalar,
1246 sae->tmp->own_commit_element_ffc,
1247 sae->peer_commit_scalar,
1248 sae->tmp->peer_commit_element_ffc,
1249 wpabuf_put(buf, SHA256_MAC_LEN));
1250 }
1251
1252
sae_check_confirm(struct sae_data * sae,const u8 * data,size_t len)1253 int sae_check_confirm(struct sae_data *sae, const u8 *data, size_t len)
1254 {
1255 u8 verifier[SHA256_MAC_LEN];
1256
1257 if (len < 2 + SHA256_MAC_LEN) {
1258 wpa_printf(MSG_DEBUG, "SAE: Too short confirm message");
1259 return -1;
1260 }
1261
1262 wpa_printf(MSG_DEBUG, "SAE: peer-send-confirm %u", WPA_GET_LE16(data));
1263
1264 if (sae->tmp == NULL) {
1265 wpa_printf(MSG_DEBUG, "SAE: Temporary data not yet available");
1266 return -1;
1267 }
1268
1269 if (sae->tmp->ec)
1270 sae_cn_confirm_ecc(sae, data, sae->peer_commit_scalar,
1271 sae->tmp->peer_commit_element_ecc,
1272 sae->tmp->own_commit_scalar,
1273 sae->tmp->own_commit_element_ecc,
1274 verifier);
1275 else
1276 sae_cn_confirm_ffc(sae, data, sae->peer_commit_scalar,
1277 sae->tmp->peer_commit_element_ffc,
1278 sae->tmp->own_commit_scalar,
1279 sae->tmp->own_commit_element_ffc,
1280 verifier);
1281
1282 if (os_memcmp_const(verifier, data + 2, SHA256_MAC_LEN) != 0) {
1283 wpa_printf(MSG_DEBUG, "SAE: Confirm mismatch");
1284 wpa_hexdump(MSG_DEBUG, "SAE: Received confirm",
1285 data + 2, SHA256_MAC_LEN);
1286 wpa_hexdump(MSG_DEBUG, "SAE: Calculated verifier",
1287 verifier, SHA256_MAC_LEN);
1288 return -1;
1289 }
1290
1291 return 0;
1292 }
1293