2 * Simultaneous authentication of equals
3 * Copyright (c) 2012-2015, Jouni Malinen <j@w1.fi>
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
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"
20 int sae_set_group(struct sae_data *sae, int group)
22 struct sae_temporary_data *tmp;
25 tmp = sae->tmp = os_zalloc(sizeof(*tmp));
29 /* First, check if this is an ECC group */
30 tmp->ec = crypto_ec_init(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);
39 /* Not an ECC group, check FFC */
40 tmp->dh = dh_groups_get(group);
43 tmp->prime_len = tmp->dh->prime_len;
44 if (tmp->prime_len > SAE_MAX_PRIME_LEN) {
49 tmp->prime_buf = crypto_bignum_init_set(tmp->dh->prime,
51 if (tmp->prime_buf == NULL) {
55 tmp->prime = tmp->prime_buf;
57 tmp->order_buf = crypto_bignum_init_set(tmp->dh->order,
59 if (tmp->order_buf == NULL) {
63 tmp->order = tmp->order_buf;
68 /* Unsupported group */
73 void sae_clear_temp_data(struct sae_data *sae)
75 struct sae_temporary_data *tmp;
76 if (sae == NULL || sae->tmp == NULL)
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));
96 void sae_clear_data(struct sae_data *sae)
100 sae_clear_temp_data(sae);
101 crypto_bignum_deinit(sae->peer_commit_scalar, 0);
102 os_memset(sae, 0, sizeof(*sae));
106 static void buf_shift_right(u8 *buf, size_t len, size_t bits)
109 for (i = len - 1; i > 0; i--)
110 buf[i] = (buf[i - 1] << (8 - bits)) | (buf[i] >> bits);
115 static struct crypto_bignum * sae_get_rand(struct sae_data *sae)
117 u8 val[SAE_MAX_PRIME_LEN];
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;
123 if (order_len > sizeof(val))
127 if (iter++ > 100 || random_get_bytes(val, order_len) < 0)
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);
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);
143 os_memset(val, 0, order_len);
148 static struct crypto_bignum * sae_get_rand_and_mask(struct sae_data *sae)
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)
154 return sae_get_rand(sae);
158 static void sae_pwd_seed_key(const u8 *addr1, const u8 *addr2, u8 *key)
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);
166 os_memcpy(key, addr2, ETH_ALEN);
167 os_memcpy(key + ETH_ALEN, addr1, ETH_ALEN);
172 static struct crypto_bignum *
173 get_rand_1_to_p_1(const u8 *prime, size_t prime_len, size_t prime_bits,
177 struct crypto_bignum *r;
178 u8 tmp[SAE_MAX_ECC_PRIME_LEN];
180 if (random_get_bytes(tmp, prime_len) < 0)
183 buf_shift_right(tmp, prime_len, 8 - prime_bits % 8);
184 if (os_memcmp(tmp, prime, prime_len) >= 0)
186 r = crypto_bignum_init_set(tmp, prime_len);
189 if (crypto_bignum_is_zero(r)) {
190 crypto_bignum_deinit(r, 0);
194 *r_odd = tmp[prime_len - 1] & 0x01;
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)
208 struct crypto_bignum *r, *num;
209 int r_odd, check, res = -1;
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.
217 * r = a random number between 1 and p-1, inclusive
218 * num = (v * r * r) modulo p
220 r = get_rand_1_to_p_1(prime, sae->tmp->prime_len, bits, &r_odd);
224 num = crypto_bignum_init();
226 crypto_bignum_mulmod(y_sqr, r, sae->tmp->prime, num) < 0 ||
227 crypto_bignum_mulmod(num, r, sae->tmp->prime, num) < 0)
232 * num = (num * qr) module p
233 * LGR(num, p) = 1 ==> quadratic residue
235 if (crypto_bignum_mulmod(num, qr, sae->tmp->prime, num) < 0)
240 * num = (num * qnr) module p
241 * LGR(num, p) = -1 ==> quadratic residue
243 if (crypto_bignum_mulmod(num, qnr, sae->tmp->prime, num) < 0)
248 res = crypto_bignum_legendre(num, sae->tmp->prime);
255 crypto_bignum_deinit(num, 1);
256 crypto_bignum_deinit(r, 1);
261 static int sae_test_pwd_seed_ecc(struct sae_data *sae, const u8 *pwd_seed,
263 const struct crypto_bignum *qr,
264 const struct crypto_bignum *qnr,
265 struct crypto_bignum **ret_x_cand)
267 u8 pwd_value[SAE_MAX_ECC_PRIME_LEN];
268 struct crypto_bignum *y_sqr, *x_cand;
274 wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-seed", pwd_seed, SHA256_MAC_LEN);
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);
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);
285 if (os_memcmp(pwd_value, prime, sae->tmp->prime_len) >= 0)
288 x_cand = crypto_bignum_init_set(pwd_value, sae->tmp->prime_len);
291 y_sqr = crypto_ec_point_compute_y_sqr(sae->tmp->ec, x_cand);
293 crypto_bignum_deinit(x_cand, 1);
297 res = is_quadratic_residue_blind(sae, prime, bits, qr, qnr, y_sqr);
298 crypto_bignum_deinit(y_sqr, 1);
300 crypto_bignum_deinit(x_cand, 1);
304 *ret_x_cand = x_cand;
309 static int sae_test_pwd_seed_ffc(struct sae_data *sae, const u8 *pwd_seed,
310 struct crypto_bignum *pwe)
312 u8 pwd_value[SAE_MAX_PRIME_LEN];
313 size_t bits = sae->tmp->prime_len * 8;
315 struct crypto_bignum *a, *b;
318 wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-seed", pwd_seed, SHA256_MAC_LEN);
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,
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);
329 if (os_memcmp(pwd_value, sae->tmp->dh->prime, sae->tmp->prime_len) >= 0)
331 wpa_printf(MSG_DEBUG, "SAE: pwd-value >= p");
335 /* PWE = pwd-value^((p-1)/r) modulo p */
337 a = crypto_bignum_init_set(pwd_value, sae->tmp->prime_len);
339 if (sae->tmp->dh->safe_prime) {
341 * r = (p-1)/2 for the group used here, so this becomes:
342 * PWE = pwd-value^2 modulo p
345 b = crypto_bignum_init_set(exp, sizeof(exp));
347 /* Calculate exponent: (p-1)/r */
349 b = crypto_bignum_init_set(exp, sizeof(exp));
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);
358 if (a == NULL || b == NULL)
361 res = crypto_bignum_exptmod(a, b, sae->tmp->prime, pwe);
363 crypto_bignum_deinit(a, 0);
364 crypto_bignum_deinit(b, 0);
367 wpa_printf(MSG_DEBUG, "SAE: Failed to calculate PWE");
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");
377 wpa_printf(MSG_DEBUG, "SAE: PWE found");
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)
390 while (!(*qr) || !(*qnr)) {
391 u8 tmp[SAE_MAX_ECC_PRIME_LEN];
392 struct crypto_bignum *q;
395 if (random_get_bytes(tmp, prime_len) < 0)
398 buf_shift_right(tmp, prime_len, 8 - prime_bits % 8);
399 if (os_memcmp(tmp, prime, prime_len) >= 0)
401 q = crypto_bignum_init_set(tmp, prime_len);
404 res = crypto_bignum_legendre(q, prime_bn);
406 if (res == 1 && !(*qr))
408 else if (res == -1 && !(*qnr))
411 crypto_bignum_deinit(q, 0);
414 return (*qr && *qnr) ? 0 : -1;
418 static int sae_derive_pwe_ecc(struct sae_data *sae, const u8 *addr1,
419 const u8 *addr2, const u8 *password,
423 u8 addrs[2 * ETH_ALEN];
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];
431 struct crypto_bignum *x = NULL, *qr, *qnr;
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)
441 prime_len = sae->tmp->prime_len;
442 if (crypto_bignum_to_bin(sae->tmp->prime, prime, sizeof(prime),
445 bits = crypto_ec_prime_len_bits(sae->tmp->ec);
448 * Create a random quadratic residue (qr) and quadratic non-residue
449 * (qnr) modulo p for blinding purposes during the loop.
451 if (get_random_qr_qnr(prime, prime_len, sae->tmp->prime, bits,
455 wpa_hexdump_ascii_key(MSG_DEBUG, "SAE: password",
456 password, password_len);
459 * H(salt, ikm) = HMAC-SHA256(salt, ikm)
461 * pwd-seed = H(MAX(STA-A-MAC, STA-B-MAC) || MIN(STA-A-MAC, STA-B-MAC),
464 sae_pwd_seed_key(addr1, addr2, addrs);
467 len[0] = password_len;
469 len[1] = sizeof(counter);
472 * Continue for at least k iterations to protect against side-channel
473 * attacks that attempt to determine the number of iterations required
476 for (counter = 1; counter <= k || !x; counter++) {
477 u8 pwd_seed[SHA256_MAC_LEN];
478 struct crypto_bignum *x_cand;
481 /* This should not happen in practice */
482 wpa_printf(MSG_DEBUG, "SAE: Failed to derive PWE");
486 wpa_printf(MSG_DEBUG, "SAE: counter = %u", counter);
487 if (hmac_sha256_vector(addrs, sizeof(addrs), 2, addr, len,
491 res = sae_test_pwd_seed_ecc(sae, pwd_seed,
492 prime, qr, qnr, &x_cand);
496 wpa_printf(MSG_DEBUG,
497 "SAE: Selected pwd-seed with counter %u",
500 pwd_seed_odd = pwd_seed[SHA256_MAC_LEN - 1] & 0x01;
501 os_memset(pwd_seed, 0, sizeof(pwd_seed));
504 * Use a dummy password for the following rounds, if
507 addr[0] = dummy_password;
508 len[0] = dummy_password_len;
509 } else if (res > 0) {
510 crypto_bignum_deinit(x_cand, 1);
515 wpa_printf(MSG_DEBUG, "SAE: Could not generate PWE");
520 if (!sae->tmp->pwe_ecc)
521 sae->tmp->pwe_ecc = crypto_ec_point_init(sae->tmp->ec);
522 if (!sae->tmp->pwe_ecc)
525 res = crypto_ec_point_solve_y_coord(sae->tmp->ec,
526 sae->tmp->pwe_ecc, x,
528 crypto_bignum_deinit(x, 1);
531 * This should not happen since we already checked that there
534 wpa_printf(MSG_DEBUG, "SAE: Could not solve y");
538 crypto_bignum_deinit(qr, 0);
539 crypto_bignum_deinit(qnr, 0);
545 static int sae_derive_pwe_ffc(struct sae_data *sae, const u8 *addr1,
546 const u8 *addr2, const u8 *password,
550 u8 addrs[2 * ETH_ALEN];
555 if (sae->tmp->pwe_ffc == NULL) {
556 sae->tmp->pwe_ffc = crypto_bignum_init();
557 if (sae->tmp->pwe_ffc == NULL)
561 wpa_hexdump_ascii_key(MSG_DEBUG, "SAE: password",
562 password, password_len);
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)
569 sae_pwd_seed_key(addr1, addr2, addrs);
572 len[0] = password_len;
574 len[1] = sizeof(counter);
576 for (counter = 1; !found; counter++) {
577 u8 pwd_seed[SHA256_MAC_LEN];
581 /* This should not happen in practice */
582 wpa_printf(MSG_DEBUG, "SAE: Failed to derive PWE");
586 wpa_printf(MSG_DEBUG, "SAE: counter = %u", counter);
587 if (hmac_sha256_vector(addrs, sizeof(addrs), 2, addr, len,
590 res = sae_test_pwd_seed_ffc(sae, pwd_seed, sae->tmp->pwe_ffc);
594 wpa_printf(MSG_DEBUG, "SAE: Use this PWE");
599 return found ? 0 : -1;
603 static int sae_derive_commit_element_ecc(struct sae_data *sae,
604 struct crypto_bignum *mask)
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)
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");
626 static int sae_derive_commit_element_ffc(struct sae_data *sae,
627 struct crypto_bignum *mask)
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)
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,
640 sae->tmp->own_commit_element_ffc) < 0) {
641 wpa_printf(MSG_DEBUG, "SAE: Could not compute commit-element");
649 static int sae_derive_commit(struct sae_data *sae)
651 struct crypto_bignum *mask;
653 unsigned int counter = 0;
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
667 mask = sae_get_rand_and_mask(sae);
669 wpa_printf(MSG_DEBUG, "SAE: Could not get rand/mask");
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)
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));
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))
692 crypto_bignum_deinit(mask, 1);
697 int sae_prepare_commit(const u8 *addr1, const u8 *addr2,
698 const u8 *password, size_t password_len,
699 struct sae_data *sae)
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)
712 static int sae_derive_k_ecc(struct sae_data *sae, u8 *k)
714 struct crypto_ec_point *K;
717 K = crypto_ec_point_init(sae->tmp->ec);
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)
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");
739 wpa_hexdump_key(MSG_DEBUG, "SAE: k", k, sae->tmp->prime_len);
743 crypto_ec_point_deinit(K, 1);
748 static int sae_derive_k_ffc(struct sae_data *sae, u8 *k)
750 struct crypto_bignum *K;
753 K = crypto_bignum_init();
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)
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
770 crypto_bignum_is_one(K) ||
771 crypto_bignum_to_bin(K, k, SAE_MAX_PRIME_LEN, sae->tmp->prime_len) <
773 wpa_printf(MSG_DEBUG, "SAE: Failed to calculate K and k");
777 wpa_hexdump_key(MSG_DEBUG, "SAE: k", k, sae->tmp->prime_len);
781 crypto_bignum_deinit(K, 1);
786 static int sae_derive_keys(struct sae_data *sae, const u8 *k)
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;
794 tmp = crypto_bignum_init();
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)
804 os_memset(null_key, 0, sizeof(null_key));
805 hmac_sha256(null_key, sizeof(null_key), k, sae->tmp->prime_len,
807 wpa_hexdump_key(MSG_DEBUG, "SAE: keyseed", keyseed, sizeof(keyseed));
809 crypto_bignum_add(sae->tmp->own_commit_scalar, sae->peer_commit_scalar,
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);
825 crypto_bignum_deinit(tmp, 0);
830 int sae_process_commit(struct sae_data *sae)
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)
842 void sae_write_commit(struct sae_data *sae, struct wpabuf *buf,
843 const struct wpabuf *token)
847 if (sae->tmp == NULL)
850 wpabuf_put_le16(buf, sae->group); /* Finite Cyclic Group */
852 wpabuf_put_buf(buf, token);
853 wpa_hexdump(MSG_DEBUG, "SAE: Anti-clogging token",
854 wpabuf_head(token), wpabuf_len(token));
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);
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);
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);
880 u16 sae_group_allowed(struct sae_data *sae, int *allowed_groups, u16 group)
882 if (allowed_groups) {
884 for (i = 0; allowed_groups[i] > 0; i++) {
885 if (allowed_groups[i] == group)
888 if (allowed_groups[i] != group) {
889 wpa_printf(MSG_DEBUG, "SAE: Proposed group %u not "
890 "enabled in the current configuration",
892 return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
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;
901 if (group != sae->group && sae_set_group(sae, group) < 0) {
902 wpa_printf(MSG_DEBUG, "SAE: Unsupported Finite Cyclic Group %u",
904 return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
907 if (sae->tmp == NULL) {
908 wpa_printf(MSG_DEBUG, "SAE: Group information not yet initialized");
909 return WLAN_STATUS_UNSPECIFIED_FAILURE;
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;
918 return WLAN_STATUS_SUCCESS;
922 static void sae_parse_commit_token(struct sae_data *sae, const u8 **pos,
923 const u8 *end, const u8 **token,
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);
944 static u16 sae_parse_commit_scalar(struct sae_data *sae, const u8 **pos,
947 struct crypto_bignum *peer_scalar;
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;
954 peer_scalar = crypto_bignum_init_set(*pos, sae->tmp->prime_len);
955 if (peer_scalar == NULL)
956 return WLAN_STATUS_UNSPECIFIED_FAILURE;
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.
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;
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;
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;
988 return WLAN_STATUS_SUCCESS;
992 static u16 sae_parse_commit_element_ecc(struct sae_data *sae, const u8 *pos,
995 u8 prime[SAE_MAX_ECC_PRIME_LEN];
997 if (pos + 2 * sae->tmp->prime_len > end) {
998 wpa_printf(MSG_DEBUG, "SAE: Not enough data for "
1000 return WLAN_STATUS_UNSPECIFIED_FAILURE;
1003 if (crypto_bignum_to_bin(sae->tmp->prime, prime, sizeof(prime),
1004 sae->tmp->prime_len) < 0)
1005 return WLAN_STATUS_UNSPECIFIED_FAILURE;
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 "
1013 return WLAN_STATUS_UNSPECIFIED_FAILURE;
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);
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;
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;
1033 return WLAN_STATUS_SUCCESS;
1037 static u16 sae_parse_commit_element_ffc(struct sae_data *sae, const u8 *pos,
1040 struct crypto_bignum *res, *one;
1041 const u8 one_bin[1] = { 0x01 };
1043 if (pos + sae->tmp->prime_len > end) {
1044 wpa_printf(MSG_DEBUG, "SAE: Not enough data for "
1046 return WLAN_STATUS_UNSPECIFIED_FAILURE;
1048 wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-element", pos,
1049 sae->tmp->prime_len);
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));
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;
1069 crypto_bignum_deinit(one, 0);
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;
1079 crypto_bignum_deinit(res, 0);
1081 return WLAN_STATUS_SUCCESS;
1085 static u16 sae_parse_commit_element(struct sae_data *sae, const u8 *pos,
1089 return sae_parse_commit_element_ffc(sae, pos, end);
1090 return sae_parse_commit_element_ecc(sae, pos, end);
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)
1097 const u8 *pos = data, *end = data + len;
1100 /* Check Finite Cyclic Group */
1102 return WLAN_STATUS_UNSPECIFIED_FAILURE;
1103 res = sae_group_allowed(sae, allowed_groups, WPA_GET_LE16(pos));
1104 if (res != WLAN_STATUS_SUCCESS)
1108 /* Optional Anti-Clogging Token */
1109 sae_parse_commit_token(sae, &pos, end, token, token_len);
1112 res = sae_parse_commit_scalar(sae, &pos, end);
1113 if (res != WLAN_STATUS_SUCCESS)
1116 /* commit-element */
1117 res = sae_parse_commit_element(sae, pos, end);
1118 if (res != WLAN_STATUS_SUCCESS)
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.
1125 if (!sae->tmp->own_commit_scalar ||
1126 crypto_bignum_cmp(sae->tmp->own_commit_scalar,
1127 sae->peer_commit_scalar) != 0 ||
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)) ||
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 */
1140 * This is a reflection attack - return special value to trigger caller
1141 * to silently discard the frame instead of replying with a specific
1144 return SAE_SILENTLY_DISCARD;
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,
1157 u8 scalar_b1[SAE_MAX_PRIME_LEN], scalar_b2[SAE_MAX_PRIME_LEN];
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)
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;
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;
1180 len[4] = element2_len;
1181 hmac_sha256_vector(sae->tmp->kck, sizeof(sae->tmp->kck), 5, addr, len,
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,
1193 u8 element_b1[2 * SAE_MAX_ECC_PRIME_LEN];
1194 u8 element_b2[2 * SAE_MAX_ECC_PRIME_LEN];
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);
1201 sae_cn_confirm(sae, sc, scalar1, element_b1, 2 * sae->tmp->prime_len,
1202 scalar2, element_b2, 2 * sae->tmp->prime_len, 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,
1213 u8 element_b1[SAE_MAX_PRIME_LEN];
1214 u8 element_b2[SAE_MAX_PRIME_LEN];
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);
1221 sae_cn_confirm(sae, sc, scalar1, element_b1, sae->tmp->prime_len,
1222 scalar2, element_b2, sae->tmp->prime_len, confirm);
1226 void sae_write_confirm(struct sae_data *sae, struct wpabuf *buf)
1230 if (sae->tmp == NULL)
1234 sc = wpabuf_put(buf, 0);
1235 wpabuf_put_le16(buf, sae->send_confirm);
1236 sae->send_confirm++;
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));
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));
1253 int sae_check_confirm(struct sae_data *sae, const u8 *data, size_t len)
1255 u8 verifier[SHA256_MAC_LEN];
1257 if (len < 2 + SHA256_MAC_LEN) {
1258 wpa_printf(MSG_DEBUG, "SAE: Too short confirm message");
1262 wpa_printf(MSG_DEBUG, "SAE: peer-send-confirm %u", WPA_GET_LE16(data));
1264 if (sae->tmp == NULL) {
1265 wpa_printf(MSG_DEBUG, "SAE: Temporary data not yet available");
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,
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,
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);