/* * Simultaneous authentication of equals * Copyright (c) 2012-2016, Jouni Malinen * * This software may be distributed under the terms of the BSD license. * See README for more details. */ #include "includes.h" #include "common.h" #include "utils/const_time.h" #include "crypto/crypto.h" #include "crypto/sha256.h" #include "crypto/sha384.h" #include "crypto/sha512.h" #include "crypto/random.h" #include "crypto/dh_groups.h" #include "ieee802_11_defs.h" #include "dragonfly.h" #include "sae.h" int sae_set_group(struct sae_data *sae, int group) { struct sae_temporary_data *tmp; #ifdef CONFIG_TESTING_OPTIONS /* Allow all groups for testing purposes in non-production builds. */ #else /* CONFIG_TESTING_OPTIONS */ if (!dragonfly_suitable_group(group, 0)) { wpa_printf(MSG_DEBUG, "SAE: Reject unsuitable group %d", group); return -1; } #endif /* CONFIG_TESTING_OPTIONS */ sae_clear_data(sae); tmp = sae->tmp = os_zalloc(sizeof(*tmp)); if (tmp == NULL) return -1; /* First, check if this is an ECC group */ tmp->ec = crypto_ec_init(group); if (tmp->ec) { wpa_printf(MSG_DEBUG, "SAE: Selecting supported ECC group %d", group); sae->group = group; tmp->prime_len = crypto_ec_prime_len(tmp->ec); tmp->prime = crypto_ec_get_prime(tmp->ec); tmp->order_len = crypto_ec_order_len(tmp->ec); tmp->order = crypto_ec_get_order(tmp->ec); return 0; } /* Not an ECC group, check FFC */ tmp->dh = dh_groups_get(group); if (tmp->dh) { wpa_printf(MSG_DEBUG, "SAE: Selecting supported FFC group %d", group); sae->group = group; tmp->prime_len = tmp->dh->prime_len; if (tmp->prime_len > SAE_MAX_PRIME_LEN) { sae_clear_data(sae); return -1; } tmp->prime_buf = crypto_bignum_init_set(tmp->dh->prime, tmp->prime_len); if (tmp->prime_buf == NULL) { sae_clear_data(sae); return -1; } tmp->prime = tmp->prime_buf; tmp->order_len = tmp->dh->order_len; tmp->order_buf = crypto_bignum_init_set(tmp->dh->order, tmp->dh->order_len); if (tmp->order_buf == NULL) { sae_clear_data(sae); return -1; } tmp->order = tmp->order_buf; return 0; } /* Unsupported group */ wpa_printf(MSG_DEBUG, "SAE: Group %d not supported by the crypto library", group); return -1; } void sae_clear_temp_data(struct sae_data *sae) { struct sae_temporary_data *tmp; if (sae == NULL || sae->tmp == NULL) return; tmp = sae->tmp; crypto_ec_deinit(tmp->ec); crypto_bignum_deinit(tmp->prime_buf, 0); crypto_bignum_deinit(tmp->order_buf, 0); crypto_bignum_deinit(tmp->sae_rand, 1); crypto_bignum_deinit(tmp->pwe_ffc, 1); crypto_bignum_deinit(tmp->own_commit_scalar, 0); crypto_bignum_deinit(tmp->own_commit_element_ffc, 0); crypto_bignum_deinit(tmp->peer_commit_element_ffc, 0); crypto_ec_point_deinit(tmp->pwe_ecc, 1); crypto_ec_point_deinit(tmp->own_commit_element_ecc, 0); crypto_ec_point_deinit(tmp->peer_commit_element_ecc, 0); wpabuf_free(tmp->anti_clogging_token); wpabuf_free(tmp->own_rejected_groups); wpabuf_free(tmp->peer_rejected_groups); os_free(tmp->pw_id); bin_clear_free(tmp, sizeof(*tmp)); sae->tmp = NULL; } void sae_clear_data(struct sae_data *sae) { if (sae == NULL) return; sae_clear_temp_data(sae); crypto_bignum_deinit(sae->peer_commit_scalar, 0); os_memset(sae, 0, sizeof(*sae)); } static void sae_pwd_seed_key(const u8 *addr1, const u8 *addr2, u8 *key) { wpa_printf(MSG_DEBUG, "SAE: PWE derivation - addr1=" MACSTR " addr2=" MACSTR, MAC2STR(addr1), MAC2STR(addr2)); if (os_memcmp(addr1, addr2, ETH_ALEN) > 0) { os_memcpy(key, addr1, ETH_ALEN); os_memcpy(key + ETH_ALEN, addr2, ETH_ALEN); } else { os_memcpy(key, addr2, ETH_ALEN); os_memcpy(key + ETH_ALEN, addr1, ETH_ALEN); } } static int sae_test_pwd_seed_ecc(struct sae_data *sae, const u8 *pwd_seed, const u8 *prime, const u8 *qr, const u8 *qnr, u8 *pwd_value) { struct crypto_bignum *y_sqr, *x_cand; int res; size_t bits; int cmp_prime; unsigned int in_range; wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-seed", pwd_seed, SHA256_MAC_LEN); /* pwd-value = KDF-z(pwd-seed, "SAE Hunting and Pecking", p) */ bits = crypto_ec_prime_len_bits(sae->tmp->ec); if (sha256_prf_bits(pwd_seed, SHA256_MAC_LEN, "SAE Hunting and Pecking", prime, sae->tmp->prime_len, pwd_value, bits) < 0) return -1; if (bits % 8) buf_shift_right(pwd_value, sae->tmp->prime_len, 8 - bits % 8); wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value", pwd_value, sae->tmp->prime_len); cmp_prime = const_time_memcmp(pwd_value, prime, sae->tmp->prime_len); /* Create a const_time mask for selection based on prf result * being smaller than prime. */ in_range = const_time_fill_msb((unsigned int) cmp_prime); /* The algorithm description would skip the next steps if * cmp_prime >= 0 (reutnr 0 here), but go through them regardless to * minimize externally observable differences in behavior. */ x_cand = crypto_bignum_init_set(pwd_value, sae->tmp->prime_len); if (!x_cand) return -1; y_sqr = crypto_ec_point_compute_y_sqr(sae->tmp->ec, x_cand); crypto_bignum_deinit(x_cand, 1); if (!y_sqr) return -1; res = dragonfly_is_quadratic_residue_blind(sae->tmp->ec, qr, qnr, y_sqr); crypto_bignum_deinit(y_sqr, 1); if (res < 0) return res; return const_time_select_int(in_range, res, 0); } /* Returns -1 on fatal failure, 0 if PWE cannot be derived from the provided * pwd-seed, or 1 if a valid PWE was derived from pwd-seed. */ static int sae_test_pwd_seed_ffc(struct sae_data *sae, const u8 *pwd_seed, struct crypto_bignum *pwe) { u8 pwd_value[SAE_MAX_PRIME_LEN]; size_t bits = sae->tmp->prime_len * 8; u8 exp[1]; struct crypto_bignum *a, *b = NULL; int res, is_val; u8 pwd_value_valid; wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-seed", pwd_seed, SHA256_MAC_LEN); /* pwd-value = KDF-z(pwd-seed, "SAE Hunting and Pecking", p) */ if (sha256_prf_bits(pwd_seed, SHA256_MAC_LEN, "SAE Hunting and Pecking", sae->tmp->dh->prime, sae->tmp->prime_len, pwd_value, bits) < 0) return -1; wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value", pwd_value, sae->tmp->prime_len); /* Check whether pwd-value < p */ res = const_time_memcmp(pwd_value, sae->tmp->dh->prime, sae->tmp->prime_len); /* pwd-value >= p is invalid, so res is < 0 for the valid cases and * the negative sign can be used to fill the mask for constant time * selection */ pwd_value_valid = const_time_fill_msb(res); /* If pwd-value >= p, force pwd-value to be < p and perform the * calculations anyway to hide timing difference. The derived PWE will * be ignored in that case. */ pwd_value[0] = const_time_select_u8(pwd_value_valid, pwd_value[0], 0); /* PWE = pwd-value^((p-1)/r) modulo p */ res = -1; a = crypto_bignum_init_set(pwd_value, sae->tmp->prime_len); if (!a) goto fail; /* This is an optimization based on the used group that does not depend * on the password in any way, so it is fine to use separate branches * for this step without constant time operations. */ if (sae->tmp->dh->safe_prime) { /* * r = (p-1)/2 for the group used here, so this becomes: * PWE = pwd-value^2 modulo p */ exp[0] = 2; b = crypto_bignum_init_set(exp, sizeof(exp)); } else { /* Calculate exponent: (p-1)/r */ exp[0] = 1; b = crypto_bignum_init_set(exp, sizeof(exp)); if (b == NULL || crypto_bignum_sub(sae->tmp->prime, b, b) < 0 || crypto_bignum_div(b, sae->tmp->order, b) < 0) goto fail; } if (!b) goto fail; res = crypto_bignum_exptmod(a, b, sae->tmp->prime, pwe); if (res < 0) goto fail; /* There were no fatal errors in calculations, so determine the return * value using constant time operations. We get here for number of * invalid cases which are cleared here after having performed all the * computation. PWE is valid if pwd-value was less than prime and * PWE > 1. Start with pwd-value check first and then use constant time * operations to clear res to 0 if PWE is 0 or 1. */ res = const_time_select_u8(pwd_value_valid, 1, 0); is_val = crypto_bignum_is_zero(pwe); res = const_time_select_u8(const_time_is_zero(is_val), res, 0); is_val = crypto_bignum_is_one(pwe); res = const_time_select_u8(const_time_is_zero(is_val), res, 0); fail: crypto_bignum_deinit(a, 1); crypto_bignum_deinit(b, 1); return res; } static int sae_derive_pwe_ecc(struct sae_data *sae, const u8 *addr1, const u8 *addr2, const u8 *password, size_t password_len, const char *identifier) { u8 counter, k; u8 addrs[2 * ETH_ALEN]; const u8 *addr[3]; size_t len[3]; size_t num_elem; u8 *dummy_password, *tmp_password; int pwd_seed_odd = 0; u8 prime[SAE_MAX_ECC_PRIME_LEN]; size_t prime_len; struct crypto_bignum *x = NULL, *qr = NULL, *qnr = NULL; u8 x_bin[SAE_MAX_ECC_PRIME_LEN]; u8 x_cand_bin[SAE_MAX_ECC_PRIME_LEN]; u8 qr_bin[SAE_MAX_ECC_PRIME_LEN]; u8 qnr_bin[SAE_MAX_ECC_PRIME_LEN]; int res = -1; u8 found = 0; /* 0 (false) or 0xff (true) to be used as const_time_* * mask */ os_memset(x_bin, 0, sizeof(x_bin)); dummy_password = os_malloc(password_len); tmp_password = os_malloc(password_len); if (!dummy_password || !tmp_password || random_get_bytes(dummy_password, password_len) < 0) goto fail; prime_len = sae->tmp->prime_len; if (crypto_bignum_to_bin(sae->tmp->prime, prime, sizeof(prime), prime_len) < 0) goto fail; /* * Create a random quadratic residue (qr) and quadratic non-residue * (qnr) modulo p for blinding purposes during the loop. */ if (dragonfly_get_random_qr_qnr(sae->tmp->prime, &qr, &qnr) < 0 || crypto_bignum_to_bin(qr, qr_bin, sizeof(qr_bin), prime_len) < 0 || crypto_bignum_to_bin(qnr, qnr_bin, sizeof(qnr_bin), prime_len) < 0) goto fail; wpa_hexdump_ascii_key(MSG_DEBUG, "SAE: password", password, password_len); if (identifier) wpa_printf(MSG_DEBUG, "SAE: password identifier: %s", identifier); /* * H(salt, ikm) = HMAC-SHA256(salt, ikm) * base = password [|| identifier] * pwd-seed = H(MAX(STA-A-MAC, STA-B-MAC) || MIN(STA-A-MAC, STA-B-MAC), * base || counter) */ sae_pwd_seed_key(addr1, addr2, addrs); addr[0] = tmp_password; len[0] = password_len; num_elem = 1; if (identifier) { addr[num_elem] = (const u8 *) identifier; len[num_elem] = os_strlen(identifier); num_elem++; } addr[num_elem] = &counter; len[num_elem] = sizeof(counter); num_elem++; /* * Continue for at least k iterations to protect against side-channel * attacks that attempt to determine the number of iterations required * in the loop. */ k = dragonfly_min_pwe_loop_iter(sae->group); for (counter = 1; counter <= k || !found; counter++) { u8 pwd_seed[SHA256_MAC_LEN]; if (counter > 200) { /* This should not happen in practice */ wpa_printf(MSG_DEBUG, "SAE: Failed to derive PWE"); break; } wpa_printf(MSG_DEBUG, "SAE: counter = %03u", counter); const_time_select_bin(found, dummy_password, password, password_len, tmp_password); if (hmac_sha256_vector(addrs, sizeof(addrs), num_elem, addr, len, pwd_seed) < 0) break; res = sae_test_pwd_seed_ecc(sae, pwd_seed, prime, qr_bin, qnr_bin, x_cand_bin); const_time_select_bin(found, x_bin, x_cand_bin, prime_len, x_bin); pwd_seed_odd = const_time_select_u8( found, pwd_seed_odd, pwd_seed[SHA256_MAC_LEN - 1] & 0x01); os_memset(pwd_seed, 0, sizeof(pwd_seed)); if (res < 0) goto fail; /* Need to minimize differences in handling res == 0 and 1 here * to avoid differences in timing and instruction cache access, * so use const_time_select_*() to make local copies of the * values based on whether this loop iteration was the one that * found the pwd-seed/x. */ /* found is 0 or 0xff here and res is 0 or 1. Bitwise OR of them * (with res converted to 0/0xff) handles this in constant time. */ found |= res * 0xff; wpa_printf(MSG_DEBUG, "SAE: pwd-seed result %d found=0x%02x", res, found); } if (!found) { wpa_printf(MSG_DEBUG, "SAE: Could not generate PWE"); res = -1; goto fail; } x = crypto_bignum_init_set(x_bin, prime_len); if (!x) { res = -1; goto fail; } if (!sae->tmp->pwe_ecc) sae->tmp->pwe_ecc = crypto_ec_point_init(sae->tmp->ec); if (!sae->tmp->pwe_ecc) res = -1; else res = crypto_ec_point_solve_y_coord(sae->tmp->ec, sae->tmp->pwe_ecc, x, pwd_seed_odd); if (res < 0) { /* * This should not happen since we already checked that there * is a result. */ wpa_printf(MSG_DEBUG, "SAE: Could not solve y"); } fail: crypto_bignum_deinit(qr, 0); crypto_bignum_deinit(qnr, 0); os_free(dummy_password); bin_clear_free(tmp_password, password_len); crypto_bignum_deinit(x, 1); os_memset(x_bin, 0, sizeof(x_bin)); os_memset(x_cand_bin, 0, sizeof(x_cand_bin)); return res; } static int sae_derive_pwe_ffc(struct sae_data *sae, const u8 *addr1, const u8 *addr2, const u8 *password, size_t password_len, const char *identifier) { u8 counter, k, sel_counter = 0; u8 addrs[2 * ETH_ALEN]; const u8 *addr[3]; size_t len[3]; size_t num_elem; u8 found = 0; /* 0 (false) or 0xff (true) to be used as const_time_* * mask */ u8 mask; struct crypto_bignum *pwe; size_t prime_len = sae->tmp->prime_len * 8; u8 *pwe_buf; crypto_bignum_deinit(sae->tmp->pwe_ffc, 1); sae->tmp->pwe_ffc = NULL; /* Allocate a buffer to maintain selected and candidate PWE for constant * time selection. */ pwe_buf = os_zalloc(prime_len * 2); pwe = crypto_bignum_init(); if (!pwe_buf || !pwe) goto fail; wpa_hexdump_ascii_key(MSG_DEBUG, "SAE: password", password, password_len); /* * H(salt, ikm) = HMAC-SHA256(salt, ikm) * pwd-seed = H(MAX(STA-A-MAC, STA-B-MAC) || MIN(STA-A-MAC, STA-B-MAC), * password [|| identifier] || counter) */ sae_pwd_seed_key(addr1, addr2, addrs); addr[0] = password; len[0] = password_len; num_elem = 1; if (identifier) { addr[num_elem] = (const u8 *) identifier; len[num_elem] = os_strlen(identifier); num_elem++; } addr[num_elem] = &counter; len[num_elem] = sizeof(counter); num_elem++; k = dragonfly_min_pwe_loop_iter(sae->group); for (counter = 1; counter <= k || !found; counter++) { u8 pwd_seed[SHA256_MAC_LEN]; int res; if (counter > 200) { /* This should not happen in practice */ wpa_printf(MSG_DEBUG, "SAE: Failed to derive PWE"); break; } wpa_printf(MSG_DEBUG, "SAE: counter = %02u", counter); if (hmac_sha256_vector(addrs, sizeof(addrs), num_elem, addr, len, pwd_seed) < 0) break; res = sae_test_pwd_seed_ffc(sae, pwd_seed, pwe); /* res is -1 for fatal failure, 0 if a valid PWE was not found, * or 1 if a valid PWE was found. */ if (res < 0) break; /* Store the candidate PWE into the second half of pwe_buf and * the selected PWE in the beginning of pwe_buf using constant * time selection. */ if (crypto_bignum_to_bin(pwe, pwe_buf + prime_len, prime_len, prime_len) < 0) break; const_time_select_bin(found, pwe_buf, pwe_buf + prime_len, prime_len, pwe_buf); sel_counter = const_time_select_u8(found, sel_counter, counter); mask = const_time_eq_u8(res, 1); found = const_time_select_u8(found, found, mask); } if (!found) goto fail; wpa_printf(MSG_DEBUG, "SAE: Use PWE from counter = %02u", sel_counter); sae->tmp->pwe_ffc = crypto_bignum_init_set(pwe_buf, prime_len); fail: crypto_bignum_deinit(pwe, 1); bin_clear_free(pwe_buf, prime_len * 2); return sae->tmp->pwe_ffc ? 0 : -1; } static int hkdf_extract(size_t hash_len, const u8 *salt, size_t salt_len, size_t num_elem, const u8 *addr[], const size_t len[], u8 *prk) { if (hash_len == 32) return hmac_sha256_vector(salt, salt_len, num_elem, addr, len, prk); #ifdef CONFIG_SHA384 if (hash_len == 48) return hmac_sha384_vector(salt, salt_len, num_elem, addr, len, prk); #endif /* CONFIG_SHA384 */ #ifdef CONFIG_SHA512 if (hash_len == 64) return hmac_sha512_vector(salt, salt_len, num_elem, addr, len, prk); #endif /* CONFIG_SHA512 */ return -1; } static int hkdf_expand(size_t hash_len, const u8 *prk, size_t prk_len, const char *info, u8 *okm, size_t okm_len) { size_t info_len = os_strlen(info); if (hash_len == 32) return hmac_sha256_kdf(prk, prk_len, NULL, (const u8 *) info, info_len, okm, okm_len); #ifdef CONFIG_SHA384 if (hash_len == 48) return hmac_sha384_kdf(prk, prk_len, NULL, (const u8 *) info, info_len, okm, okm_len); #endif /* CONFIG_SHA384 */ #ifdef CONFIG_SHA512 if (hash_len == 64) return hmac_sha512_kdf(prk, prk_len, NULL, (const u8 *) info, info_len, okm, okm_len); #endif /* CONFIG_SHA512 */ return -1; } static int sswu_curve_param(int group, int *z) { switch (group) { case 19: case 20: case 21: case 28: *z = -2; return 0; case 25: case 29: *z = -5; return 0; case 26: *z = -11; return 0; case 30: *z = 2; return 0; } return -1; } static void debug_print_bignum(const char *title, const struct crypto_bignum *a, size_t prime_len) { u8 *bin; bin = os_malloc(prime_len); if (bin && crypto_bignum_to_bin(a, bin, prime_len, prime_len) >= 0) wpa_hexdump_key(MSG_DEBUG, title, bin, prime_len); else wpa_printf(MSG_DEBUG, "Could not print bignum (%s)", title); bin_clear_free(bin, prime_len); } static struct crypto_ec_point * sswu(struct crypto_ec *ec, int group, const struct crypto_bignum *u) { int z_int; const struct crypto_bignum *a, *b, *prime; struct crypto_bignum *u2, *t1, *t2, *z, *t, *zero, *one, *two, *three, *x1a, *x1b, *y = NULL; struct crypto_bignum *x1 = NULL, *x2, *gx1, *gx2, *v = NULL; unsigned int m_is_zero, is_qr, is_eq; size_t prime_len; u8 bin[SAE_MAX_ECC_PRIME_LEN]; u8 bin1[SAE_MAX_ECC_PRIME_LEN]; u8 bin2[SAE_MAX_ECC_PRIME_LEN]; u8 x_y[2 * SAE_MAX_ECC_PRIME_LEN]; struct crypto_ec_point *p = NULL; if (sswu_curve_param(group, &z_int) < 0) return NULL; prime = crypto_ec_get_prime(ec); prime_len = crypto_ec_prime_len(ec); a = crypto_ec_get_a(ec); b = crypto_ec_get_b(ec); u2 = crypto_bignum_init(); t1 = crypto_bignum_init(); t2 = crypto_bignum_init(); z = crypto_bignum_init_uint(abs(z_int)); t = crypto_bignum_init(); zero = crypto_bignum_init_uint(0); one = crypto_bignum_init_uint(1); two = crypto_bignum_init_uint(2); three = crypto_bignum_init_uint(3); x1a = crypto_bignum_init(); x1b = crypto_bignum_init(); x2 = crypto_bignum_init(); gx1 = crypto_bignum_init(); gx2 = crypto_bignum_init(); if (!u2 || !t1 || !t2 || !z || !t || !zero || !one || !two || !three || !x1a || !x1b || !x2 || !gx1 || !gx2) goto fail; if (z_int < 0 && crypto_bignum_sub(prime, z, z) < 0) goto fail; /* m = z^2 * u^4 + z * u^2 */ /* --> tmp = z * u^2, m = tmp^2 + tmp */ /* u2 = u^2 * t1 = z * u2 * t2 = t1^2 * m = t1 = t1 + t2 */ if (crypto_bignum_sqrmod(u, prime, u2) < 0 || crypto_bignum_mulmod(z, u2, prime, t1) < 0 || crypto_bignum_sqrmod(t1, prime, t2) < 0 || crypto_bignum_addmod(t1, t2, prime, t1) < 0) goto fail; debug_print_bignum("SSWU: m", t1, prime_len); /* l = CEQ(m, 0) * t = CSEL(l, 0, inverse(m); where inverse(x) is calculated as * x^(p-2) modulo p which will handle m == 0 case correctly */ /* TODO: Make sure crypto_bignum_is_zero() is constant time */ m_is_zero = const_time_eq(crypto_bignum_is_zero(t1), 1); /* t = m^(p-2) modulo p */ if (crypto_bignum_sub(prime, two, t2) < 0 || crypto_bignum_exptmod(t1, t2, prime, t) < 0) goto fail; debug_print_bignum("SSWU: t", t, prime_len); /* b / (z * a) */ if (crypto_bignum_mulmod(z, a, prime, t1) < 0 || crypto_bignum_inverse(t1, prime, t1) < 0 || crypto_bignum_mulmod(b, t1, prime, x1a) < 0) goto fail; debug_print_bignum("SSWU: x1a = b / (z * a)", x1a, prime_len); /* (-b/a) * (1 + t) */ if (crypto_bignum_sub(prime, b, t1) < 0 || crypto_bignum_inverse(a, prime, t2) < 0 || crypto_bignum_mulmod(t1, t2, prime, t1) < 0 || crypto_bignum_addmod(one, t, prime, t2) < 0 || crypto_bignum_mulmod(t1, t2, prime, x1b) < 0) goto fail; debug_print_bignum("SSWU: x1b = (-b/a) * (1 + t)", x1b, prime_len); /* x1 = CSEL(CEQ(m, 0), x1a, x1b) */ if (crypto_bignum_to_bin(x1a, bin1, sizeof(bin1), prime_len) < 0 || crypto_bignum_to_bin(x1b, bin2, sizeof(bin2), prime_len) < 0) goto fail; const_time_select_bin(m_is_zero, bin1, bin2, prime_len, bin); x1 = crypto_bignum_init_set(bin, prime_len); debug_print_bignum("SSWU: x1 = CSEL(l, x1a, x1b)", x1, prime_len); /* gx1 = x1^3 + a * x1 + b */ if (crypto_bignum_exptmod(x1, three, prime, t1) < 0 || crypto_bignum_mulmod(a, x1, prime, t2) < 0 || crypto_bignum_addmod(t1, t2, prime, t1) < 0 || crypto_bignum_addmod(t1, b, prime, gx1) < 0) goto fail; debug_print_bignum("SSWU: gx1 = x1^3 + a * x1 + b", gx1, prime_len); /* x2 = z * u^2 * x1 */ if (crypto_bignum_mulmod(z, u2, prime, t1) < 0 || crypto_bignum_mulmod(t1, x1, prime, x2) < 0) goto fail; debug_print_bignum("SSWU: x2 = z * u^2 * x1", x2, prime_len); /* gx2 = x2^3 + a * x2 + b */ if (crypto_bignum_exptmod(x2, three, prime, t1) < 0 || crypto_bignum_mulmod(a, x2, prime, t2) < 0 || crypto_bignum_addmod(t1, t2, prime, t1) < 0 || crypto_bignum_addmod(t1, b, prime, gx2) < 0) goto fail; debug_print_bignum("SSWU: gx2 = x2^3 + a * x2 + b", gx2, prime_len); /* l = gx1 is a quadratic residue modulo p * --> gx1^((p-1)/2) modulo p is zero or one */ if (crypto_bignum_sub(prime, one, t1) < 0 || crypto_bignum_rshift(t1, 1, t1) < 0 || crypto_bignum_exptmod(gx1, t1, prime, t1) < 0) goto fail; debug_print_bignum("SSWU: gx1^((p-1)/2) modulo p", t1, prime_len); is_qr = const_time_eq(crypto_bignum_is_zero(t1) | crypto_bignum_is_one(t1), 1); /* v = CSEL(l, gx1, gx2) */ if (crypto_bignum_to_bin(gx1, bin1, sizeof(bin1), prime_len) < 0 || crypto_bignum_to_bin(gx2, bin2, sizeof(bin2), prime_len) < 0) goto fail; const_time_select_bin(is_qr, bin1, bin2, prime_len, bin); v = crypto_bignum_init_set(bin, prime_len); debug_print_bignum("SSWU: v = CSEL(l, gx1, gx2)", v, prime_len); /* x = CSEL(l, x1, x2) */ if (crypto_bignum_to_bin(x1, bin1, sizeof(bin1), prime_len) < 0 || crypto_bignum_to_bin(x2, bin2, sizeof(bin2), prime_len) < 0) goto fail; const_time_select_bin(is_qr, bin1, bin2, prime_len, x_y); wpa_hexdump_key(MSG_DEBUG, "SSWU: x = CSEL(l, x1, x2)", x_y, prime_len); /* y = sqrt(v) */ y = crypto_bignum_init(); /* TODO: Remove p = 3 mod 4 check and disable group 26 instead(?) */ if (crypto_bignum_to_bin(prime, bin1, sizeof(bin1), prime_len) < 0) goto fail; if ((bin1[prime_len - 1] & 0x03) == 3) { /* For prime p such that p = 3 mod 4 --> v^((p+1)/4) */ if (!y || crypto_bignum_add(prime, one, t1) < 0 || crypto_bignum_rshift(t1, 2, t1) < 0 || crypto_bignum_exptmod(v, t1, prime, y) < 0) goto fail; } else { wpa_printf(MSG_DEBUG, "SSWU: prime does not have p = 3 mod 4"); if (!y || crypto_bignum_sqrtmod(v, prime, y) < 0) goto fail; } debug_print_bignum("SSWU: y = sqrt(v)", y, prime_len); /* l = CEQ(LSB(u), LSB(y)) */ if (crypto_bignum_to_bin(u, bin1, sizeof(bin1), prime_len) < 0 || crypto_bignum_to_bin(y, bin2, sizeof(bin2), prime_len) < 0) goto fail; is_eq = const_time_eq(bin1[prime_len - 1] & 0x01, bin2[prime_len - 1] & 0x01); /* P = CSEL(l, (x,y), (x, p-y)) */ if (crypto_bignum_sub(prime, y, t1) < 0) goto fail; debug_print_bignum("SSWU: p - y", t1, prime_len); if (crypto_bignum_to_bin(y, bin1, sizeof(bin1), prime_len) < 0 || crypto_bignum_to_bin(t1, bin2, sizeof(bin2), prime_len) < 0) goto fail; const_time_select_bin(is_eq, bin1, bin2, prime_len, &x_y[prime_len]); /* output P */ wpa_hexdump_key(MSG_DEBUG, "SSWU: P.x", x_y, prime_len); wpa_hexdump_key(MSG_DEBUG, "SSWU: P.y", &x_y[prime_len], prime_len); p = crypto_ec_point_from_bin(ec, x_y); fail: crypto_bignum_deinit(u2, 1); crypto_bignum_deinit(t1, 1); crypto_bignum_deinit(t2, 1); crypto_bignum_deinit(z, 0); crypto_bignum_deinit(t, 1); crypto_bignum_deinit(x1a, 1); crypto_bignum_deinit(x1b, 1); crypto_bignum_deinit(x1, 1); crypto_bignum_deinit(x2, 1); crypto_bignum_deinit(gx1, 1); crypto_bignum_deinit(gx2, 1); crypto_bignum_deinit(y, 1); crypto_bignum_deinit(v, 1); crypto_bignum_deinit(zero, 0); crypto_bignum_deinit(one, 0); crypto_bignum_deinit(two, 0); crypto_bignum_deinit(three, 0); forced_memzero(bin, sizeof(bin)); forced_memzero(bin1, sizeof(bin1)); forced_memzero(bin2, sizeof(bin2)); forced_memzero(x_y, sizeof(x_y)); return p; } static int sae_pwd_seed(size_t hash_len, const u8 *ssid, size_t ssid_len, const u8 *password, size_t password_len, const char *identifier, u8 *pwd_seed) { const u8 *addr[2]; size_t len[2]; size_t num_elem; /* pwd-seed = HKDF-Extract(ssid, password [ || identifier ]) */ addr[0] = password; len[0] = password_len; num_elem = 1; wpa_hexdump_ascii(MSG_DEBUG, "SAE: SSID", ssid, ssid_len); wpa_hexdump_ascii_key(MSG_DEBUG, "SAE: password", password, password_len); if (identifier) { wpa_printf(MSG_DEBUG, "SAE: password identifier: %s", identifier); addr[num_elem] = (const u8 *) identifier; len[num_elem] = os_strlen(identifier); num_elem++; } if (hkdf_extract(hash_len, ssid, ssid_len, num_elem, addr, len, pwd_seed) < 0) return -1; wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-seed", pwd_seed, hash_len); return 0; } size_t sae_ecc_prime_len_2_hash_len(size_t prime_len) { if (prime_len <= 256 / 8) return 32; if (prime_len <= 384 / 8) return 48; return 64; } struct crypto_ec_point * sae_derive_pt_ecc(struct crypto_ec *ec, int group, const u8 *ssid, size_t ssid_len, const u8 *password, size_t password_len, const char *identifier) { u8 pwd_seed[64]; u8 pwd_value[SAE_MAX_ECC_PRIME_LEN * 2]; size_t pwd_value_len, hash_len, prime_len; const struct crypto_bignum *prime; struct crypto_bignum *bn = NULL; struct crypto_ec_point *p1 = NULL, *p2 = NULL, *pt = NULL; prime = crypto_ec_get_prime(ec); prime_len = crypto_ec_prime_len(ec); if (prime_len > SAE_MAX_ECC_PRIME_LEN) goto fail; hash_len = sae_ecc_prime_len_2_hash_len(prime_len); /* len = olen(p) + ceil(olen(p)/2) */ pwd_value_len = prime_len + (prime_len + 1) / 2; if (sae_pwd_seed(hash_len, ssid, ssid_len, password, password_len, identifier, pwd_seed) < 0) goto fail; /* pwd-value = HKDF-Expand(pwd-seed, "SAE Hash to Element u1 P1", len) */ if (hkdf_expand(hash_len, pwd_seed, hash_len, "SAE Hash to Element u1 P1", pwd_value, pwd_value_len) < 0) goto fail; wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value (u1 P1)", pwd_value, pwd_value_len); /* u1 = pwd-value modulo p */ bn = crypto_bignum_init_set(pwd_value, pwd_value_len); if (!bn || crypto_bignum_mod(bn, prime, bn) < 0 || crypto_bignum_to_bin(bn, pwd_value, sizeof(pwd_value), prime_len) < 0) goto fail; wpa_hexdump_key(MSG_DEBUG, "SAE: u1", pwd_value, prime_len); /* P1 = SSWU(u1) */ p1 = sswu(ec, group, bn); if (!p1) goto fail; /* pwd-value = HKDF-Expand(pwd-seed, "SAE Hash to Element u2 P2", len) */ if (hkdf_expand(hash_len, pwd_seed, hash_len, "SAE Hash to Element u2 P2", pwd_value, pwd_value_len) < 0) goto fail; wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value (u2 P2)", pwd_value, pwd_value_len); /* u2 = pwd-value modulo p */ crypto_bignum_deinit(bn, 1); bn = crypto_bignum_init_set(pwd_value, pwd_value_len); if (!bn || crypto_bignum_mod(bn, prime, bn) < 0 || crypto_bignum_to_bin(bn, pwd_value, sizeof(pwd_value), prime_len) < 0) goto fail; wpa_hexdump_key(MSG_DEBUG, "SAE: u2", pwd_value, prime_len); /* P2 = SSWU(u2) */ p2 = sswu(ec, group, bn); if (!p2) goto fail; /* PT = elem-op(P1, P2) */ pt = crypto_ec_point_init(ec); if (!pt) goto fail; if (crypto_ec_point_add(ec, p1, p2, pt) < 0) { crypto_ec_point_deinit(pt, 1); pt = NULL; } fail: forced_memzero(pwd_seed, sizeof(pwd_seed)); forced_memzero(pwd_value, sizeof(pwd_value)); crypto_bignum_deinit(bn, 1); crypto_ec_point_deinit(p1, 1); crypto_ec_point_deinit(p2, 1); return pt; } size_t sae_ffc_prime_len_2_hash_len(size_t prime_len) { if (prime_len <= 2048 / 8) return 32; if (prime_len <= 3072 / 8) return 48; return 64; } static struct crypto_bignum * sae_derive_pt_ffc(const struct dh_group *dh, int group, const u8 *ssid, size_t ssid_len, const u8 *password, size_t password_len, const char *identifier) { size_t hash_len, prime_len, pwd_value_len; struct crypto_bignum *prime, *order; struct crypto_bignum *one = NULL, *two = NULL, *bn = NULL, *tmp = NULL, *pt = NULL; u8 pwd_seed[64]; u8 pwd_value[SAE_MAX_PRIME_LEN + SAE_MAX_PRIME_LEN / 2]; prime = crypto_bignum_init_set(dh->prime, dh->prime_len); order = crypto_bignum_init_set(dh->order, dh->order_len); if (!prime || !order) goto fail; prime_len = dh->prime_len; if (prime_len > SAE_MAX_PRIME_LEN) goto fail; hash_len = sae_ffc_prime_len_2_hash_len(prime_len); /* len = olen(p) + ceil(olen(p)/2) */ pwd_value_len = prime_len + (prime_len + 1) / 2; if (pwd_value_len > sizeof(pwd_value)) goto fail; if (sae_pwd_seed(hash_len, ssid, ssid_len, password, password_len, identifier, pwd_seed) < 0) goto fail; /* pwd-value = HKDF-Expand(pwd-seed, "SAE Hash to Element", len) */ if (hkdf_expand(hash_len, pwd_seed, hash_len, "SAE Hash to Element", pwd_value, pwd_value_len) < 0) goto fail; wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value", pwd_value, pwd_value_len); /* pwd-value = (pwd-value modulo (p-2)) + 2 */ bn = crypto_bignum_init_set(pwd_value, pwd_value_len); one = crypto_bignum_init_uint(1); two = crypto_bignum_init_uint(2); tmp = crypto_bignum_init(); if (!bn || !one || !two || !tmp || crypto_bignum_sub(prime, two, tmp) < 0 || crypto_bignum_mod(bn, tmp, bn) < 0 || crypto_bignum_add(bn, two, bn) < 0 || crypto_bignum_to_bin(bn, pwd_value, sizeof(pwd_value), prime_len) < 0) goto fail; wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value(reduced)", pwd_value, prime_len); /* PT = pwd-value^((p-1)/q) modulo p */ pt = crypto_bignum_init(); if (!pt || crypto_bignum_sub(prime, one, tmp) < 0 || crypto_bignum_div(tmp, order, tmp) < 0 || crypto_bignum_exptmod(bn, tmp, prime, pt) < 0) { crypto_bignum_deinit(pt, 1); pt = NULL; goto fail; } debug_print_bignum("SAE: PT", pt, prime_len); fail: forced_memzero(pwd_seed, sizeof(pwd_seed)); forced_memzero(pwd_value, sizeof(pwd_value)); crypto_bignum_deinit(bn, 1); crypto_bignum_deinit(tmp, 1); crypto_bignum_deinit(one, 0); crypto_bignum_deinit(two, 0); crypto_bignum_deinit(prime, 0); crypto_bignum_deinit(order, 0); return pt; } static struct sae_pt * sae_derive_pt_group(int group, const u8 *ssid, size_t ssid_len, const u8 *password, size_t password_len, const char *identifier) { struct sae_pt *pt; wpa_printf(MSG_DEBUG, "SAE: Derive PT - group %d", group); pt = os_zalloc(sizeof(*pt)); if (!pt) return NULL; pt->group = group; pt->ec = crypto_ec_init(group); if (pt->ec) { pt->ecc_pt = sae_derive_pt_ecc(pt->ec, group, ssid, ssid_len, password, password_len, identifier); if (!pt->ecc_pt) { wpa_printf(MSG_DEBUG, "SAE: Failed to derive PT"); goto fail; } return pt; } pt->dh = dh_groups_get(group); if (!pt->dh) { wpa_printf(MSG_DEBUG, "SAE: Unsupported group %d", group); goto fail; } pt->ffc_pt = sae_derive_pt_ffc(pt->dh, group, ssid, ssid_len, password, password_len, identifier); if (!pt->ffc_pt) { wpa_printf(MSG_DEBUG, "SAE: Failed to derive PT"); goto fail; } return pt; fail: sae_deinit_pt(pt); return NULL; } struct sae_pt * sae_derive_pt(int *groups, const u8 *ssid, size_t ssid_len, const u8 *password, size_t password_len, const char *identifier) { struct sae_pt *pt = NULL, *last = NULL, *tmp; int default_groups[] = { 19, 0 }; int i; if (!groups) groups = default_groups; for (i = 0; groups[i] > 0; i++) { tmp = sae_derive_pt_group(groups[i], ssid, ssid_len, password, password_len, identifier); if (!tmp) continue; if (last) last->next = tmp; else pt = tmp; last = tmp; } return pt; } static void sae_max_min_addr(const u8 *addr[], size_t len[], const u8 *addr1, const u8 *addr2) { len[0] = ETH_ALEN; len[1] = ETH_ALEN; if (os_memcmp(addr1, addr2, ETH_ALEN) > 0) { addr[0] = addr1; addr[1] = addr2; } else { addr[0] = addr2; addr[1] = addr1; } } struct crypto_ec_point * sae_derive_pwe_from_pt_ecc(const struct sae_pt *pt, const u8 *addr1, const u8 *addr2) { u8 bin[SAE_MAX_ECC_PRIME_LEN * 2]; size_t prime_len; const u8 *addr[2]; size_t len[2]; u8 salt[64], hash[64]; size_t hash_len; const struct crypto_bignum *order; struct crypto_bignum *tmp = NULL, *val = NULL, *one = NULL; struct crypto_ec_point *pwe = NULL; wpa_printf(MSG_DEBUG, "SAE: Derive PWE from PT"); prime_len = crypto_ec_prime_len(pt->ec); if (crypto_ec_point_to_bin(pt->ec, pt->ecc_pt, bin, bin + prime_len) < 0) return NULL; wpa_hexdump_key(MSG_DEBUG, "SAE: PT.x", bin, prime_len); wpa_hexdump_key(MSG_DEBUG, "SAE: PT.y", bin + prime_len, prime_len); sae_max_min_addr(addr, len, addr1, addr2); /* val = H(0^n, * MAX(STA-A-MAC, STA-B-MAC) || MIN(STA-A-MAC, STA-B-MAC)) */ wpa_printf(MSG_DEBUG, "SAE: val = H(0^n, MAX(addrs) || MIN(addrs))"); hash_len = sae_ecc_prime_len_2_hash_len(prime_len); os_memset(salt, 0, hash_len); if (hkdf_extract(hash_len, salt, hash_len, 2, addr, len, hash) < 0) goto fail; wpa_hexdump(MSG_DEBUG, "SAE: val", hash, hash_len); /* val = val modulo (q - 1) + 1 */ order = crypto_ec_get_order(pt->ec); tmp = crypto_bignum_init(); val = crypto_bignum_init_set(hash, hash_len); one = crypto_bignum_init_uint(1); if (!tmp || !val || !one || crypto_bignum_sub(order, one, tmp) < 0 || crypto_bignum_mod(val, tmp, val) < 0 || crypto_bignum_add(val, one, val) < 0) goto fail; debug_print_bignum("SAE: val(reduced to 1..q-1)", val, prime_len); /* PWE = scalar-op(val, PT) */ pwe = crypto_ec_point_init(pt->ec); if (!pwe || crypto_ec_point_mul(pt->ec, pt->ecc_pt, val, pwe) < 0 || crypto_ec_point_to_bin(pt->ec, pwe, bin, bin + prime_len) < 0) { crypto_ec_point_deinit(pwe, 1); pwe = NULL; goto fail; } wpa_hexdump_key(MSG_DEBUG, "SAE: PWE.x", bin, prime_len); wpa_hexdump_key(MSG_DEBUG, "SAE: PWE.y", bin + prime_len, prime_len); fail: crypto_bignum_deinit(tmp, 1); crypto_bignum_deinit(val, 1); crypto_bignum_deinit(one, 0); return pwe; } struct crypto_bignum * sae_derive_pwe_from_pt_ffc(const struct sae_pt *pt, const u8 *addr1, const u8 *addr2) { size_t prime_len; const u8 *addr[2]; size_t len[2]; u8 salt[64], hash[64]; size_t hash_len; struct crypto_bignum *tmp = NULL, *val = NULL, *one = NULL; struct crypto_bignum *pwe = NULL, *order = NULL, *prime = NULL; wpa_printf(MSG_DEBUG, "SAE: Derive PWE from PT"); prime = crypto_bignum_init_set(pt->dh->prime, pt->dh->prime_len); order = crypto_bignum_init_set(pt->dh->order, pt->dh->order_len); if (!prime || !order) goto fail; prime_len = pt->dh->prime_len; sae_max_min_addr(addr, len, addr1, addr2); /* val = H(0^n, * MAX(STA-A-MAC, STA-B-MAC) || MIN(STA-A-MAC, STA-B-MAC)) */ wpa_printf(MSG_DEBUG, "SAE: val = H(0^n, MAX(addrs) || MIN(addrs))"); hash_len = sae_ffc_prime_len_2_hash_len(prime_len); os_memset(salt, 0, hash_len); if (hkdf_extract(hash_len, salt, hash_len, 2, addr, len, hash) < 0) goto fail; wpa_hexdump(MSG_DEBUG, "SAE: val", hash, hash_len); /* val = val modulo (q - 1) + 1 */ tmp = crypto_bignum_init(); val = crypto_bignum_init_set(hash, hash_len); one = crypto_bignum_init_uint(1); if (!tmp || !val || !one || crypto_bignum_sub(order, one, tmp) < 0 || crypto_bignum_mod(val, tmp, val) < 0 || crypto_bignum_add(val, one, val) < 0) goto fail; debug_print_bignum("SAE: val(reduced to 1..q-1)", val, prime_len); /* PWE = scalar-op(val, PT) */ pwe = crypto_bignum_init(); if (!pwe || crypto_bignum_exptmod(pt->ffc_pt, val, prime, pwe) < 0) { crypto_bignum_deinit(pwe, 1); pwe = NULL; goto fail; } debug_print_bignum("SAE: PWE", pwe, prime_len); fail: crypto_bignum_deinit(tmp, 1); crypto_bignum_deinit(val, 1); crypto_bignum_deinit(one, 0); crypto_bignum_deinit(prime, 0); crypto_bignum_deinit(order, 0); return pwe; } void sae_deinit_pt(struct sae_pt *pt) { struct sae_pt *prev; while (pt) { crypto_ec_point_deinit(pt->ecc_pt, 1); crypto_bignum_deinit(pt->ffc_pt, 1); crypto_ec_deinit(pt->ec); prev = pt; pt = pt->next; os_free(prev); } } static int sae_derive_commit_element_ecc(struct sae_data *sae, struct crypto_bignum *mask) { /* COMMIT-ELEMENT = inverse(scalar-op(mask, PWE)) */ if (!sae->tmp->own_commit_element_ecc) { sae->tmp->own_commit_element_ecc = crypto_ec_point_init(sae->tmp->ec); if (!sae->tmp->own_commit_element_ecc) return -1; } if (crypto_ec_point_mul(sae->tmp->ec, sae->tmp->pwe_ecc, mask, sae->tmp->own_commit_element_ecc) < 0 || crypto_ec_point_invert(sae->tmp->ec, sae->tmp->own_commit_element_ecc) < 0) { wpa_printf(MSG_DEBUG, "SAE: Could not compute commit-element"); return -1; } return 0; } static int sae_derive_commit_element_ffc(struct sae_data *sae, struct crypto_bignum *mask) { /* COMMIT-ELEMENT = inverse(scalar-op(mask, PWE)) */ if (!sae->tmp->own_commit_element_ffc) { sae->tmp->own_commit_element_ffc = crypto_bignum_init(); if (!sae->tmp->own_commit_element_ffc) return -1; } if (crypto_bignum_exptmod(sae->tmp->pwe_ffc, mask, sae->tmp->prime, sae->tmp->own_commit_element_ffc) < 0 || crypto_bignum_inverse(sae->tmp->own_commit_element_ffc, sae->tmp->prime, sae->tmp->own_commit_element_ffc) < 0) { wpa_printf(MSG_DEBUG, "SAE: Could not compute commit-element"); return -1; } return 0; } static int sae_derive_commit(struct sae_data *sae) { struct crypto_bignum *mask; int ret; mask = crypto_bignum_init(); if (!sae->tmp->sae_rand) sae->tmp->sae_rand = crypto_bignum_init(); if (!sae->tmp->own_commit_scalar) sae->tmp->own_commit_scalar = crypto_bignum_init(); ret = !mask || !sae->tmp->sae_rand || !sae->tmp->own_commit_scalar || dragonfly_generate_scalar(sae->tmp->order, sae->tmp->sae_rand, mask, sae->tmp->own_commit_scalar) < 0 || (sae->tmp->ec && sae_derive_commit_element_ecc(sae, mask) < 0) || (sae->tmp->dh && sae_derive_commit_element_ffc(sae, mask) < 0); crypto_bignum_deinit(mask, 1); return ret ? -1 : 0; } int sae_prepare_commit(const u8 *addr1, const u8 *addr2, const u8 *password, size_t password_len, const char *identifier, struct sae_data *sae) { if (sae->tmp == NULL || (sae->tmp->ec && sae_derive_pwe_ecc(sae, addr1, addr2, password, password_len, identifier) < 0) || (sae->tmp->dh && sae_derive_pwe_ffc(sae, addr1, addr2, password, password_len, identifier) < 0)) return -1; sae->tmp->h2e = 0; return sae_derive_commit(sae); } int sae_prepare_commit_pt(struct sae_data *sae, const struct sae_pt *pt, const u8 *addr1, const u8 *addr2, int *rejected_groups) { if (!sae->tmp) return -1; while (pt) { if (pt->group == sae->group) break; pt = pt->next; } if (!pt) { wpa_printf(MSG_INFO, "SAE: Could not find PT for group %u", sae->group); return -1; } sae->tmp->own_addr_higher = os_memcmp(addr1, addr2, ETH_ALEN) > 0; wpabuf_free(sae->tmp->own_rejected_groups); sae->tmp->own_rejected_groups = NULL; if (rejected_groups) { int count, i; struct wpabuf *groups; count = int_array_len(rejected_groups); groups = wpabuf_alloc(count * 2); if (!groups) return -1; for (i = 0; i < count; i++) wpabuf_put_le16(groups, rejected_groups[i]); sae->tmp->own_rejected_groups = groups; } if (pt->ec) { crypto_ec_point_deinit(sae->tmp->pwe_ecc, 1); sae->tmp->pwe_ecc = sae_derive_pwe_from_pt_ecc(pt, addr1, addr2); if (!sae->tmp->pwe_ecc) return -1; } if (pt->dh) { crypto_bignum_deinit(sae->tmp->pwe_ffc, 1); sae->tmp->pwe_ffc = sae_derive_pwe_from_pt_ffc(pt, addr1, addr2); if (!sae->tmp->pwe_ffc) return -1; } sae->tmp->h2e = 1; return sae_derive_commit(sae); } static int sae_derive_k_ecc(struct sae_data *sae, u8 *k) { struct crypto_ec_point *K; int ret = -1; K = crypto_ec_point_init(sae->tmp->ec); if (K == NULL) goto fail; /* * K = scalar-op(rand, (elem-op(scalar-op(peer-commit-scalar, PWE), * PEER-COMMIT-ELEMENT))) * If K is identity element (point-at-infinity), reject * k = F(K) (= x coordinate) */ if (crypto_ec_point_mul(sae->tmp->ec, sae->tmp->pwe_ecc, sae->peer_commit_scalar, K) < 0 || crypto_ec_point_add(sae->tmp->ec, K, sae->tmp->peer_commit_element_ecc, K) < 0 || crypto_ec_point_mul(sae->tmp->ec, K, sae->tmp->sae_rand, K) < 0 || crypto_ec_point_is_at_infinity(sae->tmp->ec, K) || crypto_ec_point_to_bin(sae->tmp->ec, K, k, NULL) < 0) { wpa_printf(MSG_DEBUG, "SAE: Failed to calculate K and k"); goto fail; } wpa_hexdump_key(MSG_DEBUG, "SAE: k", k, sae->tmp->prime_len); ret = 0; fail: crypto_ec_point_deinit(K, 1); return ret; } static int sae_derive_k_ffc(struct sae_data *sae, u8 *k) { struct crypto_bignum *K; int ret = -1; K = crypto_bignum_init(); if (K == NULL) goto fail; /* * K = scalar-op(rand, (elem-op(scalar-op(peer-commit-scalar, PWE), * PEER-COMMIT-ELEMENT))) * If K is identity element (one), reject. * k = F(K) (= x coordinate) */ if (crypto_bignum_exptmod(sae->tmp->pwe_ffc, sae->peer_commit_scalar, sae->tmp->prime, K) < 0 || crypto_bignum_mulmod(K, sae->tmp->peer_commit_element_ffc, sae->tmp->prime, K) < 0 || crypto_bignum_exptmod(K, sae->tmp->sae_rand, sae->tmp->prime, K) < 0 || crypto_bignum_is_one(K) || crypto_bignum_to_bin(K, k, SAE_MAX_PRIME_LEN, sae->tmp->prime_len) < 0) { wpa_printf(MSG_DEBUG, "SAE: Failed to calculate K and k"); goto fail; } wpa_hexdump_key(MSG_DEBUG, "SAE: k", k, sae->tmp->prime_len); ret = 0; fail: crypto_bignum_deinit(K, 1); return ret; } static int sae_kdf_hash(size_t hash_len, const u8 *k, const char *label, const u8 *context, size_t context_len, u8 *out, size_t out_len) { if (hash_len == 32) return sha256_prf(k, hash_len, label, context, context_len, out, out_len); #ifdef CONFIG_SHA384 if (hash_len == 48) return sha384_prf(k, hash_len, label, context, context_len, out, out_len); #endif /* CONFIG_SHA384 */ #ifdef CONFIG_SHA512 if (hash_len == 64) return sha512_prf(k, hash_len, label, context, context_len, out, out_len); #endif /* CONFIG_SHA512 */ return -1; } static int sae_derive_keys(struct sae_data *sae, const u8 *k) { u8 zero[SAE_MAX_HASH_LEN], val[SAE_MAX_PRIME_LEN]; const u8 *salt; struct wpabuf *rejected_groups = NULL; u8 keyseed[SAE_MAX_HASH_LEN]; u8 keys[SAE_MAX_HASH_LEN + SAE_PMK_LEN]; struct crypto_bignum *tmp; int ret = -1; size_t hash_len, salt_len, prime_len = sae->tmp->prime_len; const u8 *addr[1]; size_t len[1]; tmp = crypto_bignum_init(); if (tmp == NULL) goto fail; /* keyseed = H(salt, k) * KCK || PMK = KDF-Hash-Length(keyseed, "SAE KCK and PMK", * (commit-scalar + peer-commit-scalar) modulo r) * PMKID = L((commit-scalar + peer-commit-scalar) modulo r, 0, 128) */ if (!sae->tmp->h2e) hash_len = SHA256_MAC_LEN; else if (sae->tmp->dh) hash_len = sae_ffc_prime_len_2_hash_len(prime_len); else hash_len = sae_ecc_prime_len_2_hash_len(prime_len); if (sae->tmp->h2e && (sae->tmp->own_rejected_groups || sae->tmp->peer_rejected_groups)) { struct wpabuf *own, *peer; own = sae->tmp->own_rejected_groups; peer = sae->tmp->peer_rejected_groups; salt_len = 0; if (own) salt_len += wpabuf_len(own); if (peer) salt_len += wpabuf_len(peer); rejected_groups = wpabuf_alloc(salt_len); if (!rejected_groups) goto fail; if (sae->tmp->own_addr_higher) { if (own) wpabuf_put_buf(rejected_groups, own); if (peer) wpabuf_put_buf(rejected_groups, peer); } else { if (peer) wpabuf_put_buf(rejected_groups, peer); if (own) wpabuf_put_buf(rejected_groups, own); } salt = wpabuf_head(rejected_groups); salt_len = wpabuf_len(rejected_groups); } else { os_memset(zero, 0, hash_len); salt = zero; salt_len = hash_len; } wpa_hexdump(MSG_DEBUG, "SAE: salt for keyseed derivation", salt, salt_len); addr[0] = k; len[0] = prime_len; if (hkdf_extract(hash_len, salt, salt_len, 1, addr, len, keyseed) < 0) goto fail; wpa_hexdump_key(MSG_DEBUG, "SAE: keyseed", keyseed, hash_len); if (crypto_bignum_add(sae->tmp->own_commit_scalar, sae->peer_commit_scalar, tmp) < 0 || crypto_bignum_mod(tmp, sae->tmp->order, tmp) < 0) goto fail; /* IEEE Std 802.11-2016 is not exactly clear on the encoding of the bit * string that is needed for KCK, PMK, and PMKID derivation, but it * seems to make most sense to encode the * (commit-scalar + peer-commit-scalar) mod r part as a bit string by * zero padding it from left to the length of the order (in full * octets). */ crypto_bignum_to_bin(tmp, val, sizeof(val), sae->tmp->order_len); wpa_hexdump(MSG_DEBUG, "SAE: PMKID", val, SAE_PMKID_LEN); if (sae_kdf_hash(hash_len, keyseed, "SAE KCK and PMK", val, sae->tmp->order_len, keys, hash_len + SAE_PMK_LEN) < 0) goto fail; forced_memzero(keyseed, sizeof(keyseed)); os_memcpy(sae->tmp->kck, keys, hash_len); sae->tmp->kck_len = hash_len; os_memcpy(sae->pmk, keys + hash_len, SAE_PMK_LEN); os_memcpy(sae->pmkid, val, SAE_PMKID_LEN); forced_memzero(keys, sizeof(keys)); wpa_hexdump_key(MSG_DEBUG, "SAE: KCK", sae->tmp->kck, sae->tmp->kck_len); wpa_hexdump_key(MSG_DEBUG, "SAE: PMK", sae->pmk, SAE_PMK_LEN); ret = 0; fail: wpabuf_free(rejected_groups); crypto_bignum_deinit(tmp, 0); return ret; } int sae_process_commit(struct sae_data *sae) { u8 k[SAE_MAX_PRIME_LEN]; if (sae->tmp == NULL || (sae->tmp->ec && sae_derive_k_ecc(sae, k) < 0) || (sae->tmp->dh && sae_derive_k_ffc(sae, k) < 0) || sae_derive_keys(sae, k) < 0) return -1; return 0; } void sae_write_commit(struct sae_data *sae, struct wpabuf *buf, const struct wpabuf *token, const char *identifier) { u8 *pos; if (sae->tmp == NULL) return; wpabuf_put_le16(buf, sae->group); /* Finite Cyclic Group */ if (token) { wpabuf_put_buf(buf, token); wpa_hexdump(MSG_DEBUG, "SAE: Anti-clogging token", wpabuf_head(token), wpabuf_len(token)); } pos = wpabuf_put(buf, sae->tmp->prime_len); crypto_bignum_to_bin(sae->tmp->own_commit_scalar, pos, sae->tmp->prime_len, sae->tmp->prime_len); wpa_hexdump(MSG_DEBUG, "SAE: own commit-scalar", pos, sae->tmp->prime_len); if (sae->tmp->ec) { pos = wpabuf_put(buf, 2 * sae->tmp->prime_len); crypto_ec_point_to_bin(sae->tmp->ec, sae->tmp->own_commit_element_ecc, pos, pos + sae->tmp->prime_len); wpa_hexdump(MSG_DEBUG, "SAE: own commit-element(x)", pos, sae->tmp->prime_len); wpa_hexdump(MSG_DEBUG, "SAE: own commit-element(y)", pos + sae->tmp->prime_len, sae->tmp->prime_len); } else { pos = wpabuf_put(buf, sae->tmp->prime_len); crypto_bignum_to_bin(sae->tmp->own_commit_element_ffc, pos, sae->tmp->prime_len, sae->tmp->prime_len); wpa_hexdump(MSG_DEBUG, "SAE: own commit-element", pos, sae->tmp->prime_len); } if (identifier) { /* Password Identifier element */ wpabuf_put_u8(buf, WLAN_EID_EXTENSION); wpabuf_put_u8(buf, 1 + os_strlen(identifier)); wpabuf_put_u8(buf, WLAN_EID_EXT_PASSWORD_IDENTIFIER); wpabuf_put_str(buf, identifier); wpa_printf(MSG_DEBUG, "SAE: own Password Identifier: %s", identifier); } if (sae->tmp->h2e && sae->tmp->own_rejected_groups) { wpa_hexdump_buf(MSG_DEBUG, "SAE: own Rejected Groups", sae->tmp->own_rejected_groups); wpabuf_put_u8(buf, WLAN_EID_EXTENSION); wpabuf_put_u8(buf, 1 + wpabuf_len(sae->tmp->own_rejected_groups)); wpabuf_put_u8(buf, WLAN_EID_EXT_REJECTED_GROUPS); wpabuf_put_buf(buf, sae->tmp->own_rejected_groups); } } u16 sae_group_allowed(struct sae_data *sae, int *allowed_groups, u16 group) { if (allowed_groups) { int i; for (i = 0; allowed_groups[i] > 0; i++) { if (allowed_groups[i] == group) break; } if (allowed_groups[i] != group) { wpa_printf(MSG_DEBUG, "SAE: Proposed group %u not " "enabled in the current configuration", group); return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED; } } if (sae->state == SAE_COMMITTED && group != sae->group) { wpa_printf(MSG_DEBUG, "SAE: Do not allow group to be changed"); return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED; } if (group != sae->group && sae_set_group(sae, group) < 0) { wpa_printf(MSG_DEBUG, "SAE: Unsupported Finite Cyclic Group %u", group); return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED; } if (sae->tmp == NULL) { wpa_printf(MSG_DEBUG, "SAE: Group information not yet initialized"); return WLAN_STATUS_UNSPECIFIED_FAILURE; } if (sae->tmp->dh && !allowed_groups) { wpa_printf(MSG_DEBUG, "SAE: Do not allow FFC group %u without " "explicit configuration enabling it", group); return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED; } return WLAN_STATUS_SUCCESS; } static int sae_is_password_id_elem(const u8 *pos, const u8 *end) { return end - pos >= 3 && pos[0] == WLAN_EID_EXTENSION && pos[1] >= 1 && end - pos - 2 >= pos[1] && pos[2] == WLAN_EID_EXT_PASSWORD_IDENTIFIER; } static int sae_is_rejected_groups_elem(const u8 *pos, const u8 *end) { return end - pos >= 3 && pos[0] == WLAN_EID_EXTENSION && pos[1] >= 2 && end - pos - 2 >= pos[1] && pos[2] == WLAN_EID_EXT_REJECTED_GROUPS; } static void sae_parse_commit_token(struct sae_data *sae, const u8 **pos, const u8 *end, const u8 **token, size_t *token_len, int h2e) { size_t scalar_elem_len, tlen; const u8 *elem; if (token) *token = NULL; if (token_len) *token_len = 0; scalar_elem_len = (sae->tmp->ec ? 3 : 2) * sae->tmp->prime_len; if (scalar_elem_len >= (size_t) (end - *pos)) return; /* No extra data beyond peer scalar and element */ /* It is a bit difficult to parse this now that there is an * optional variable length Anti-Clogging Token field and * optional variable length Password Identifier element in the * frame. We are sending out fixed length Anti-Clogging Token * fields, so use that length as a requirement for the received * token and check for the presence of possible Password * Identifier element based on the element header information. * When parsing H2E case, also consider the Rejected Groupd element * similarly. */ tlen = end - (*pos + scalar_elem_len); if (tlen < SHA256_MAC_LEN) { wpa_printf(MSG_DEBUG, "SAE: Too short optional data (%u octets) to include our Anti-Clogging Token", (unsigned int) tlen); return; } elem = *pos + scalar_elem_len; if (sae_is_password_id_elem(elem, end)) { /* Password Identifier element takes out all available * extra octets, so there can be no Anti-Clogging token in * this frame. */ return; } if (h2e && sae_is_rejected_groups_elem(elem, end)) { /* Rejected Groups takes out all available extra octets, so * there can be no Anti-Clogging token in this frame. */ return; } elem += SHA256_MAC_LEN; if (sae_is_password_id_elem(elem, end)) { /* Password Identifier element is included in the end, so * remove its length from the Anti-Clogging token field. */ tlen -= 2 + elem[1]; elem += 2 + elem[1]; if (h2e && sae_is_rejected_groups_elem(elem, end)) { /* Also remove Rejected Groups element from the * Anti-Clogging token field length */ tlen -= 2 + elem[1]; } } else if (h2e && sae_is_rejected_groups_elem(elem, end)) { /* Rejected Groups element is included in the end, so * remove its length from the Anti-Clogging token field. */ tlen -= 2 + elem[1]; } wpa_hexdump(MSG_DEBUG, "SAE: Anti-Clogging Token", *pos, tlen); if (token) *token = *pos; if (token_len) *token_len = tlen; *pos += tlen; } static u16 sae_parse_commit_scalar(struct sae_data *sae, const u8 **pos, const u8 *end) { struct crypto_bignum *peer_scalar; if (sae->tmp->prime_len > end - *pos) { wpa_printf(MSG_DEBUG, "SAE: Not enough data for scalar"); return WLAN_STATUS_UNSPECIFIED_FAILURE; } peer_scalar = crypto_bignum_init_set(*pos, sae->tmp->prime_len); if (peer_scalar == NULL) return WLAN_STATUS_UNSPECIFIED_FAILURE; /* * IEEE Std 802.11-2012, 11.3.8.6.1: If there is a protocol instance for * the peer and it is in Authenticated state, the new Commit Message * shall be dropped if the peer-scalar is identical to the one used in * the existing protocol instance. */ if (sae->state == SAE_ACCEPTED && sae->peer_commit_scalar && crypto_bignum_cmp(sae->peer_commit_scalar, peer_scalar) == 0) { wpa_printf(MSG_DEBUG, "SAE: Do not accept re-use of previous " "peer-commit-scalar"); crypto_bignum_deinit(peer_scalar, 0); return WLAN_STATUS_UNSPECIFIED_FAILURE; } /* 1 < scalar < r */ if (crypto_bignum_is_zero(peer_scalar) || crypto_bignum_is_one(peer_scalar) || crypto_bignum_cmp(peer_scalar, sae->tmp->order) >= 0) { wpa_printf(MSG_DEBUG, "SAE: Invalid peer scalar"); crypto_bignum_deinit(peer_scalar, 0); return WLAN_STATUS_UNSPECIFIED_FAILURE; } crypto_bignum_deinit(sae->peer_commit_scalar, 0); sae->peer_commit_scalar = peer_scalar; wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-scalar", *pos, sae->tmp->prime_len); *pos += sae->tmp->prime_len; return WLAN_STATUS_SUCCESS; } static u16 sae_parse_commit_element_ecc(struct sae_data *sae, const u8 **pos, const u8 *end) { u8 prime[SAE_MAX_ECC_PRIME_LEN]; if (2 * sae->tmp->prime_len > end - *pos) { wpa_printf(MSG_DEBUG, "SAE: Not enough data for " "commit-element"); return WLAN_STATUS_UNSPECIFIED_FAILURE; } if (crypto_bignum_to_bin(sae->tmp->prime, prime, sizeof(prime), sae->tmp->prime_len) < 0) return WLAN_STATUS_UNSPECIFIED_FAILURE; /* element x and y coordinates < p */ if (os_memcmp(*pos, prime, sae->tmp->prime_len) >= 0 || os_memcmp(*pos + sae->tmp->prime_len, prime, sae->tmp->prime_len) >= 0) { wpa_printf(MSG_DEBUG, "SAE: Invalid coordinates in peer " "element"); return WLAN_STATUS_UNSPECIFIED_FAILURE; } wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-element(x)", *pos, sae->tmp->prime_len); wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-element(y)", *pos + sae->tmp->prime_len, sae->tmp->prime_len); crypto_ec_point_deinit(sae->tmp->peer_commit_element_ecc, 0); sae->tmp->peer_commit_element_ecc = crypto_ec_point_from_bin(sae->tmp->ec, *pos); if (sae->tmp->peer_commit_element_ecc == NULL) return WLAN_STATUS_UNSPECIFIED_FAILURE; if (!crypto_ec_point_is_on_curve(sae->tmp->ec, sae->tmp->peer_commit_element_ecc)) { wpa_printf(MSG_DEBUG, "SAE: Peer element is not on curve"); return WLAN_STATUS_UNSPECIFIED_FAILURE; } *pos += 2 * sae->tmp->prime_len; return WLAN_STATUS_SUCCESS; } static u16 sae_parse_commit_element_ffc(struct sae_data *sae, const u8 **pos, const u8 *end) { struct crypto_bignum *res, *one; const u8 one_bin[1] = { 0x01 }; if (sae->tmp->prime_len > end - *pos) { wpa_printf(MSG_DEBUG, "SAE: Not enough data for " "commit-element"); return WLAN_STATUS_UNSPECIFIED_FAILURE; } wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-element", *pos, sae->tmp->prime_len); crypto_bignum_deinit(sae->tmp->peer_commit_element_ffc, 0); sae->tmp->peer_commit_element_ffc = crypto_bignum_init_set(*pos, sae->tmp->prime_len); if (sae->tmp->peer_commit_element_ffc == NULL) return WLAN_STATUS_UNSPECIFIED_FAILURE; /* 1 < element < p - 1 */ res = crypto_bignum_init(); one = crypto_bignum_init_set(one_bin, sizeof(one_bin)); if (!res || !one || crypto_bignum_sub(sae->tmp->prime, one, res) || crypto_bignum_is_zero(sae->tmp->peer_commit_element_ffc) || crypto_bignum_is_one(sae->tmp->peer_commit_element_ffc) || crypto_bignum_cmp(sae->tmp->peer_commit_element_ffc, res) >= 0) { crypto_bignum_deinit(res, 0); crypto_bignum_deinit(one, 0); wpa_printf(MSG_DEBUG, "SAE: Invalid peer element"); return WLAN_STATUS_UNSPECIFIED_FAILURE; } crypto_bignum_deinit(one, 0); /* scalar-op(r, ELEMENT) = 1 modulo p */ if (crypto_bignum_exptmod(sae->tmp->peer_commit_element_ffc, sae->tmp->order, sae->tmp->prime, res) < 0 || !crypto_bignum_is_one(res)) { wpa_printf(MSG_DEBUG, "SAE: Invalid peer element (scalar-op)"); crypto_bignum_deinit(res, 0); return WLAN_STATUS_UNSPECIFIED_FAILURE; } crypto_bignum_deinit(res, 0); *pos += sae->tmp->prime_len; return WLAN_STATUS_SUCCESS; } static u16 sae_parse_commit_element(struct sae_data *sae, const u8 **pos, const u8 *end) { if (sae->tmp->dh) return sae_parse_commit_element_ffc(sae, pos, end); return sae_parse_commit_element_ecc(sae, pos, end); } static int sae_parse_password_identifier(struct sae_data *sae, const u8 **pos, const u8 *end) { wpa_hexdump(MSG_DEBUG, "SAE: Possible elements at the end of the frame", *pos, end - *pos); if (!sae_is_password_id_elem(*pos, end)) { if (sae->tmp->pw_id) { wpa_printf(MSG_DEBUG, "SAE: No Password Identifier included, but expected one (%s)", sae->tmp->pw_id); return WLAN_STATUS_UNKNOWN_PASSWORD_IDENTIFIER; } os_free(sae->tmp->pw_id); sae->tmp->pw_id = NULL; return WLAN_STATUS_SUCCESS; /* No Password Identifier */ } if (sae->tmp->pw_id && ((*pos)[1] - 1 != (int) os_strlen(sae->tmp->pw_id) || os_memcmp(sae->tmp->pw_id, (*pos) + 3, (*pos)[1] - 1) != 0)) { wpa_printf(MSG_DEBUG, "SAE: The included Password Identifier does not match the expected one (%s)", sae->tmp->pw_id); return WLAN_STATUS_UNKNOWN_PASSWORD_IDENTIFIER; } os_free(sae->tmp->pw_id); sae->tmp->pw_id = os_malloc((*pos)[1]); if (!sae->tmp->pw_id) return WLAN_STATUS_UNSPECIFIED_FAILURE; os_memcpy(sae->tmp->pw_id, (*pos) + 3, (*pos)[1] - 1); sae->tmp->pw_id[(*pos)[1] - 1] = '\0'; wpa_hexdump_ascii(MSG_DEBUG, "SAE: Received Password Identifier", sae->tmp->pw_id, (*pos)[1] - 1); *pos = *pos + 2 + (*pos)[1]; return WLAN_STATUS_SUCCESS; } static int sae_parse_rejected_groups(struct sae_data *sae, const u8 *pos, const u8 *end) { wpa_hexdump(MSG_DEBUG, "SAE: Possible elements at the end of the frame", pos, end - pos); if (!sae_is_rejected_groups_elem(pos, end)) return WLAN_STATUS_SUCCESS; wpabuf_free(sae->tmp->peer_rejected_groups); sae->tmp->peer_rejected_groups = wpabuf_alloc(pos[1] - 1); if (!sae->tmp->peer_rejected_groups) return WLAN_STATUS_UNSPECIFIED_FAILURE; wpabuf_put_data(sae->tmp->peer_rejected_groups, pos + 3, pos[1] - 1); wpa_hexdump_buf(MSG_DEBUG, "SAE: Received Rejected Groups list", sae->tmp->peer_rejected_groups); return WLAN_STATUS_SUCCESS; } u16 sae_parse_commit(struct sae_data *sae, const u8 *data, size_t len, const u8 **token, size_t *token_len, int *allowed_groups, int h2e) { const u8 *pos = data, *end = data + len; u16 res; /* Check Finite Cyclic Group */ if (end - pos < 2) return WLAN_STATUS_UNSPECIFIED_FAILURE; res = sae_group_allowed(sae, allowed_groups, WPA_GET_LE16(pos)); if (res != WLAN_STATUS_SUCCESS) return res; pos += 2; /* Optional Anti-Clogging Token */ sae_parse_commit_token(sae, &pos, end, token, token_len, h2e); /* commit-scalar */ res = sae_parse_commit_scalar(sae, &pos, end); if (res != WLAN_STATUS_SUCCESS) return res; /* commit-element */ res = sae_parse_commit_element(sae, &pos, end); if (res != WLAN_STATUS_SUCCESS) return res; /* Optional Password Identifier element */ res = sae_parse_password_identifier(sae, &pos, end); if (res != WLAN_STATUS_SUCCESS) return res; /* Conditional Rejected Groups element */ if (h2e) { res = sae_parse_rejected_groups(sae, pos, end); if (res != WLAN_STATUS_SUCCESS) return res; } /* * Check whether peer-commit-scalar and PEER-COMMIT-ELEMENT are same as * the values we sent which would be evidence of a reflection attack. */ if (!sae->tmp->own_commit_scalar || crypto_bignum_cmp(sae->tmp->own_commit_scalar, sae->peer_commit_scalar) != 0 || (sae->tmp->dh && (!sae->tmp->own_commit_element_ffc || crypto_bignum_cmp(sae->tmp->own_commit_element_ffc, sae->tmp->peer_commit_element_ffc) != 0)) || (sae->tmp->ec && (!sae->tmp->own_commit_element_ecc || crypto_ec_point_cmp(sae->tmp->ec, sae->tmp->own_commit_element_ecc, sae->tmp->peer_commit_element_ecc) != 0))) return WLAN_STATUS_SUCCESS; /* scalars/elements are different */ /* * This is a reflection attack - return special value to trigger caller * to silently discard the frame instead of replying with a specific * status code. */ return SAE_SILENTLY_DISCARD; } static int 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) { const u8 *addr[5]; size_t len[5]; u8 scalar_b1[SAE_MAX_PRIME_LEN], scalar_b2[SAE_MAX_PRIME_LEN]; /* Confirm * CN(key, X, Y, Z, ...) = * HMAC-SHA256(key, D2OS(X) || D2OS(Y) || D2OS(Z) | ...) * confirm = CN(KCK, send-confirm, commit-scalar, COMMIT-ELEMENT, * peer-commit-scalar, PEER-COMMIT-ELEMENT) * verifier = CN(KCK, peer-send-confirm, peer-commit-scalar, * PEER-COMMIT-ELEMENT, commit-scalar, COMMIT-ELEMENT) */ if (crypto_bignum_to_bin(scalar1, scalar_b1, sizeof(scalar_b1), sae->tmp->prime_len) < 0 || crypto_bignum_to_bin(scalar2, scalar_b2, sizeof(scalar_b2), sae->tmp->prime_len) < 0) return -1; addr[0] = sc; len[0] = 2; addr[1] = scalar_b1; len[1] = sae->tmp->prime_len; addr[2] = element1; len[2] = element1_len; addr[3] = scalar_b2; len[3] = sae->tmp->prime_len; addr[4] = element2; len[4] = element2_len; return hkdf_extract(sae->tmp->kck_len, sae->tmp->kck, sae->tmp->kck_len, 5, addr, len, confirm); } static int 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) { u8 element_b1[2 * SAE_MAX_ECC_PRIME_LEN]; u8 element_b2[2 * SAE_MAX_ECC_PRIME_LEN]; if (crypto_ec_point_to_bin(sae->tmp->ec, element1, element_b1, element_b1 + sae->tmp->prime_len) < 0 || crypto_ec_point_to_bin(sae->tmp->ec, element2, element_b2, element_b2 + sae->tmp->prime_len) < 0 || sae_cn_confirm(sae, sc, scalar1, element_b1, 2 * sae->tmp->prime_len, scalar2, element_b2, 2 * sae->tmp->prime_len, confirm) < 0) return -1; return 0; } static int 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) { u8 element_b1[SAE_MAX_PRIME_LEN]; u8 element_b2[SAE_MAX_PRIME_LEN]; if (crypto_bignum_to_bin(element1, element_b1, sizeof(element_b1), sae->tmp->prime_len) < 0 || crypto_bignum_to_bin(element2, element_b2, sizeof(element_b2), sae->tmp->prime_len) < 0 || sae_cn_confirm(sae, sc, scalar1, element_b1, sae->tmp->prime_len, scalar2, element_b2, sae->tmp->prime_len, confirm) < 0) return -1; return 0; } void sae_write_confirm(struct sae_data *sae, struct wpabuf *buf) { const u8 *sc; size_t hash_len; if (sae->tmp == NULL) return; hash_len = sae->tmp->kck_len; /* Send-Confirm */ sc = wpabuf_put(buf, 0); wpabuf_put_le16(buf, sae->send_confirm); if (sae->send_confirm < 0xffff) sae->send_confirm++; if (sae->tmp->ec) sae_cn_confirm_ecc(sae, sc, sae->tmp->own_commit_scalar, sae->tmp->own_commit_element_ecc, sae->peer_commit_scalar, sae->tmp->peer_commit_element_ecc, wpabuf_put(buf, hash_len)); else sae_cn_confirm_ffc(sae, sc, sae->tmp->own_commit_scalar, sae->tmp->own_commit_element_ffc, sae->peer_commit_scalar, sae->tmp->peer_commit_element_ffc, wpabuf_put(buf, hash_len)); } int sae_check_confirm(struct sae_data *sae, const u8 *data, size_t len) { u8 verifier[SAE_MAX_HASH_LEN]; size_t hash_len; if (!sae->tmp) return -1; hash_len = sae->tmp->kck_len; if (len < 2 + hash_len) { wpa_printf(MSG_DEBUG, "SAE: Too short confirm message"); return -1; } wpa_printf(MSG_DEBUG, "SAE: peer-send-confirm %u", WPA_GET_LE16(data)); if (!sae->peer_commit_scalar || !sae->tmp->own_commit_scalar) { wpa_printf(MSG_DEBUG, "SAE: Temporary data not yet available"); return -1; } if (sae->tmp->ec) { if (!sae->tmp->peer_commit_element_ecc || !sae->tmp->own_commit_element_ecc || sae_cn_confirm_ecc(sae, data, sae->peer_commit_scalar, sae->tmp->peer_commit_element_ecc, sae->tmp->own_commit_scalar, sae->tmp->own_commit_element_ecc, verifier) < 0) return -1; } else { if (!sae->tmp->peer_commit_element_ffc || !sae->tmp->own_commit_element_ffc || sae_cn_confirm_ffc(sae, data, sae->peer_commit_scalar, sae->tmp->peer_commit_element_ffc, sae->tmp->own_commit_scalar, sae->tmp->own_commit_element_ffc, verifier) < 0) return -1; } if (os_memcmp_const(verifier, data + 2, hash_len) != 0) { wpa_printf(MSG_DEBUG, "SAE: Confirm mismatch"); wpa_hexdump(MSG_DEBUG, "SAE: Received confirm", data + 2, hash_len); wpa_hexdump(MSG_DEBUG, "SAE: Calculated verifier", verifier, hash_len); return -1; } return 0; } const char * sae_state_txt(enum sae_state state) { switch (state) { case SAE_NOTHING: return "Nothing"; case SAE_COMMITTED: return "Committed"; case SAE_CONFIRMED: return "Confirmed"; case SAE_ACCEPTED: return "Accepted"; } return "?"; }