| /* |
| * Simultaneous authentication of equals |
| * Copyright (c) 2012-2016, Jouni Malinen <j@w1.fi> |
| * |
| * 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/random.h" |
| #include "crypto/dh_groups.h" |
| #include "ieee802_11_defs.h" |
| #include "sae.h" |
| |
| |
| static int sae_suitable_group(int group) |
| { |
| #ifdef CONFIG_TESTING_OPTIONS |
| /* Allow all groups for testing purposes in non-production builds. */ |
| return 1; |
| #else /* CONFIG_TESTING_OPTIONS */ |
| /* Enforce REVmd rules on which SAE groups are suitable for production |
| * purposes: FFC groups whose prime is >= 3072 bits and ECC groups |
| * defined over a prime field whose prime is >= 256 bits. Furthermore, |
| * ECC groups defined over a characteristic 2 finite field and ECC |
| * groups with a co-factor greater than 1 are not suitable. */ |
| return group == 19 || group == 20 || group == 21 || |
| group == 28 || group == 29 || group == 30 || |
| group == 15 || group == 16 || group == 17 || group == 18; |
| #endif /* CONFIG_TESTING_OPTIONS */ |
| } |
| |
| |
| int sae_set_group(struct sae_data *sae, int group) |
| { |
| struct sae_temporary_data *tmp; |
| |
| if (!sae_suitable_group(group)) { |
| wpa_printf(MSG_DEBUG, "SAE: Reject unsuitable group %d", group); |
| return -1; |
| } |
| |
| 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 = 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_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); |
| 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 buf_shift_right(u8 *buf, size_t len, size_t bits) |
| { |
| size_t i; |
| for (i = len - 1; i > 0; i--) |
| buf[i] = (buf[i - 1] << (8 - bits)) | (buf[i] >> bits); |
| buf[0] >>= bits; |
| } |
| |
| |
| static struct crypto_bignum * sae_get_rand(struct sae_data *sae) |
| { |
| u8 val[SAE_MAX_PRIME_LEN]; |
| int iter = 0; |
| struct crypto_bignum *bn = NULL; |
| int order_len_bits = crypto_bignum_bits(sae->tmp->order); |
| size_t order_len = (order_len_bits + 7) / 8; |
| |
| if (order_len > sizeof(val)) |
| return NULL; |
| |
| for (;;) { |
| if (iter++ > 100 || random_get_bytes(val, order_len) < 0) |
| return NULL; |
| if (order_len_bits % 8) |
| buf_shift_right(val, order_len, 8 - order_len_bits % 8); |
| bn = crypto_bignum_init_set(val, order_len); |
| if (bn == NULL) |
| return NULL; |
| if (crypto_bignum_is_zero(bn) || |
| crypto_bignum_is_one(bn) || |
| crypto_bignum_cmp(bn, sae->tmp->order) >= 0) { |
| crypto_bignum_deinit(bn, 0); |
| continue; |
| } |
| break; |
| } |
| |
| os_memset(val, 0, order_len); |
| return bn; |
| } |
| |
| |
| static struct crypto_bignum * sae_get_rand_and_mask(struct sae_data *sae) |
| { |
| crypto_bignum_deinit(sae->tmp->sae_rand, 1); |
| sae->tmp->sae_rand = sae_get_rand(sae); |
| if (sae->tmp->sae_rand == NULL) |
| return NULL; |
| return sae_get_rand(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 struct crypto_bignum * |
| get_rand_1_to_p_1(const u8 *prime, size_t prime_len, size_t prime_bits, |
| int *r_odd) |
| { |
| for (;;) { |
| struct crypto_bignum *r; |
| u8 tmp[SAE_MAX_ECC_PRIME_LEN]; |
| |
| if (random_get_bytes(tmp, prime_len) < 0) |
| break; |
| if (prime_bits % 8) |
| buf_shift_right(tmp, prime_len, 8 - prime_bits % 8); |
| if (os_memcmp(tmp, prime, prime_len) >= 0) |
| continue; |
| r = crypto_bignum_init_set(tmp, prime_len); |
| if (!r) |
| break; |
| if (crypto_bignum_is_zero(r)) { |
| crypto_bignum_deinit(r, 0); |
| continue; |
| } |
| |
| *r_odd = tmp[prime_len - 1] & 0x01; |
| return r; |
| } |
| |
| return NULL; |
| } |
| |
| |
| static int is_quadratic_residue_blind(struct sae_data *sae, |
| const u8 *prime, size_t bits, |
| const u8 *qr, const u8 *qnr, |
| const struct crypto_bignum *y_sqr) |
| { |
| struct crypto_bignum *r, *num, *qr_or_qnr = NULL; |
| int r_odd, check, res = -1; |
| u8 qr_or_qnr_bin[SAE_MAX_ECC_PRIME_LEN]; |
| size_t prime_len = sae->tmp->prime_len; |
| unsigned int mask; |
| |
| /* |
| * Use the blinding technique to mask y_sqr while determining |
| * whether it is a quadratic residue modulo p to avoid leaking |
| * timing information while determining the Legendre symbol. |
| * |
| * v = y_sqr |
| * r = a random number between 1 and p-1, inclusive |
| * num = (v * r * r) modulo p |
| */ |
| r = get_rand_1_to_p_1(prime, prime_len, bits, &r_odd); |
| if (!r) |
| return -1; |
| |
| num = crypto_bignum_init(); |
| if (!num || |
| crypto_bignum_mulmod(y_sqr, r, sae->tmp->prime, num) < 0 || |
| crypto_bignum_mulmod(num, r, sae->tmp->prime, num) < 0) |
| goto fail; |
| |
| /* |
| * Need to minimize differences in handling different cases, so try to |
| * avoid branches and timing differences. |
| * |
| * If r_odd: |
| * num = (num * qr) module p |
| * LGR(num, p) = 1 ==> quadratic residue |
| * else: |
| * num = (num * qnr) module p |
| * LGR(num, p) = -1 ==> quadratic residue |
| */ |
| mask = const_time_is_zero(r_odd); |
| const_time_select_bin(mask, qnr, qr, prime_len, qr_or_qnr_bin); |
| qr_or_qnr = crypto_bignum_init_set(qr_or_qnr_bin, prime_len); |
| if (!qr_or_qnr || |
| crypto_bignum_mulmod(num, qr_or_qnr, sae->tmp->prime, num) < 0) |
| goto fail; |
| /* r_odd is 0 or 1; branchless version of check = r_odd ? 1 : -1, */ |
| check = const_time_select_int(mask, -1, 1); |
| |
| res = crypto_bignum_legendre(num, sae->tmp->prime); |
| if (res == -2) { |
| res = -1; |
| goto fail; |
| } |
| /* branchless version of res = res == check |
| * (res is -1, 0, or 1; check is -1 or 1) */ |
| mask = const_time_eq(res, check); |
| res = const_time_select_int(mask, 1, 0); |
| fail: |
| crypto_bignum_deinit(num, 1); |
| crypto_bignum_deinit(r, 1); |
| crypto_bignum_deinit(qr_or_qnr, 1); |
| return res; |
| } |
| |
| |
| 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; |
| |
| 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); |
| |
| if (const_time_memcmp(pwd_value, prime, sae->tmp->prime_len) >= 0) |
| return 0; |
| |
| 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 = is_quadratic_residue_blind(sae, prime, bits, qr, qnr, y_sqr); |
| crypto_bignum_deinit(y_sqr, 1); |
| return res; |
| } |
| |
| |
| /* 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 get_random_qr_qnr(const u8 *prime, size_t prime_len, |
| const struct crypto_bignum *prime_bn, |
| size_t prime_bits, struct crypto_bignum **qr, |
| struct crypto_bignum **qnr) |
| { |
| *qr = NULL; |
| *qnr = NULL; |
| |
| while (!(*qr) || !(*qnr)) { |
| u8 tmp[SAE_MAX_ECC_PRIME_LEN]; |
| struct crypto_bignum *q; |
| int res; |
| |
| if (random_get_bytes(tmp, prime_len) < 0) |
| break; |
| if (prime_bits % 8) |
| buf_shift_right(tmp, prime_len, 8 - prime_bits % 8); |
| if (os_memcmp(tmp, prime, prime_len) >= 0) |
| continue; |
| q = crypto_bignum_init_set(tmp, prime_len); |
| if (!q) |
| break; |
| res = crypto_bignum_legendre(q, prime_bn); |
| |
| if (res == 1 && !(*qr)) |
| *qr = q; |
| else if (res == -1 && !(*qnr)) |
| *qnr = q; |
| else |
| crypto_bignum_deinit(q, 0); |
| } |
| |
| return (*qr && *qnr) ? 0 : -1; |
| } |
| |
| |
| 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 = 40; |
| 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]; |
| size_t bits; |
| 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; |
| bits = crypto_ec_prime_len_bits(sae->tmp->ec); |
| |
| /* |
| * Create a random quadratic residue (qr) and quadratic non-residue |
| * (qnr) modulo p for blinding purposes during the loop. |
| */ |
| if (get_random_qr_qnr(prime, prime_len, sae->tmp->prime, bits, |
| &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. |
| */ |
| 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_modp_group_require_masking(int group) |
| { |
| /* Groups for which pwd-value is likely to be >= p frequently */ |
| return group == 22 || group == 23 || group == 24; |
| } |
| |
| |
| 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 = sae_modp_group_require_masking(sae->group) ? 40 : 1; |
| |
| 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 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 = -1; |
| unsigned int counter = 0; |
| |
| do { |
| counter++; |
| if (counter > 100) { |
| /* |
| * This cannot really happen in practice if the random |
| * number generator is working. Anyway, to avoid even a |
| * theoretical infinite loop, break out after 100 |
| * attemps. |
| */ |
| return -1; |
| } |
| |
| mask = sae_get_rand_and_mask(sae); |
| if (mask == NULL) { |
| wpa_printf(MSG_DEBUG, "SAE: Could not get rand/mask"); |
| return -1; |
| } |
| |
| /* commit-scalar = (rand + mask) modulo r */ |
| if (!sae->tmp->own_commit_scalar) { |
| sae->tmp->own_commit_scalar = crypto_bignum_init(); |
| if (!sae->tmp->own_commit_scalar) |
| goto fail; |
| } |
| crypto_bignum_add(sae->tmp->sae_rand, mask, |
| sae->tmp->own_commit_scalar); |
| crypto_bignum_mod(sae->tmp->own_commit_scalar, sae->tmp->order, |
| sae->tmp->own_commit_scalar); |
| } while (crypto_bignum_is_zero(sae->tmp->own_commit_scalar) || |
| crypto_bignum_is_one(sae->tmp->own_commit_scalar)); |
| |
| if ((sae->tmp->ec && sae_derive_commit_element_ecc(sae, mask) < 0) || |
| (sae->tmp->dh && sae_derive_commit_element_ffc(sae, mask) < 0)) |
| goto fail; |
| |
| ret = 0; |
| fail: |
| crypto_bignum_deinit(mask, 1); |
| return ret; |
| } |
| |
| |
| 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) || |
| sae_derive_commit(sae) < 0) |
| return -1; |
| return 0; |
| } |
| |
| |
| 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_derive_keys(struct sae_data *sae, const u8 *k) |
| { |
| u8 null_key[SAE_KEYSEED_KEY_LEN], val[SAE_MAX_PRIME_LEN]; |
| u8 keyseed[SHA256_MAC_LEN]; |
| u8 keys[SAE_KCK_LEN + SAE_PMK_LEN]; |
| struct crypto_bignum *tmp; |
| int ret = -1; |
| |
| tmp = crypto_bignum_init(); |
| if (tmp == NULL) |
| goto fail; |
| |
| /* keyseed = H(<0>32, k) |
| * KCK || PMK = KDF-512(keyseed, "SAE KCK and PMK", |
| * (commit-scalar + peer-commit-scalar) modulo r) |
| * PMKID = L((commit-scalar + peer-commit-scalar) modulo r, 0, 128) |
| */ |
| |
| os_memset(null_key, 0, sizeof(null_key)); |
| hmac_sha256(null_key, sizeof(null_key), k, sae->tmp->prime_len, |
| keyseed); |
| wpa_hexdump_key(MSG_DEBUG, "SAE: keyseed", keyseed, sizeof(keyseed)); |
| |
| crypto_bignum_add(sae->tmp->own_commit_scalar, sae->peer_commit_scalar, |
| tmp); |
| crypto_bignum_mod(tmp, sae->tmp->order, tmp); |
| crypto_bignum_to_bin(tmp, val, sizeof(val), sae->tmp->prime_len); |
| wpa_hexdump(MSG_DEBUG, "SAE: PMKID", val, SAE_PMKID_LEN); |
| if (sha256_prf(keyseed, sizeof(keyseed), "SAE KCK and PMK", |
| val, sae->tmp->prime_len, keys, sizeof(keys)) < 0) |
| goto fail; |
| os_memset(keyseed, 0, sizeof(keyseed)); |
| os_memcpy(sae->tmp->kck, keys, SAE_KCK_LEN); |
| os_memcpy(sae->pmk, keys + SAE_KCK_LEN, SAE_PMK_LEN); |
| os_memcpy(sae->pmkid, val, SAE_PMKID_LEN); |
| os_memset(keys, 0, sizeof(keys)); |
| wpa_hexdump_key(MSG_DEBUG, "SAE: KCK", sae->tmp->kck, SAE_KCK_LEN); |
| wpa_hexdump_key(MSG_DEBUG, "SAE: PMK", sae->pmk, SAE_PMK_LEN); |
| |
| ret = 0; |
| fail: |
| 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); |
| } |
| } |
| |
| |
| 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 void sae_parse_commit_token(struct sae_data *sae, const u8 **pos, |
| const u8 *end, const u8 **token, |
| size_t *token_len) |
| { |
| 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. |
| */ |
| 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; |
| } |
| |
| 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]; |
| } |
| |
| 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); |
| 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) |
| { |
| 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); |
| |
| /* 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; |
| |
| /* |
| * 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 void 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) |
| */ |
| addr[0] = sc; |
| len[0] = 2; |
| crypto_bignum_to_bin(scalar1, scalar_b1, sizeof(scalar_b1), |
| sae->tmp->prime_len); |
| addr[1] = scalar_b1; |
| len[1] = sae->tmp->prime_len; |
| addr[2] = element1; |
| len[2] = element1_len; |
| crypto_bignum_to_bin(scalar2, scalar_b2, sizeof(scalar_b2), |
| sae->tmp->prime_len); |
| addr[3] = scalar_b2; |
| len[3] = sae->tmp->prime_len; |
| addr[4] = element2; |
| len[4] = element2_len; |
| hmac_sha256_vector(sae->tmp->kck, sizeof(sae->tmp->kck), 5, addr, len, |
| confirm); |
| } |
| |
| |
| static void 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]; |
| |
| crypto_ec_point_to_bin(sae->tmp->ec, element1, element_b1, |
| element_b1 + sae->tmp->prime_len); |
| crypto_ec_point_to_bin(sae->tmp->ec, element2, element_b2, |
| element_b2 + sae->tmp->prime_len); |
| |
| sae_cn_confirm(sae, sc, scalar1, element_b1, 2 * sae->tmp->prime_len, |
| scalar2, element_b2, 2 * sae->tmp->prime_len, confirm); |
| } |
| |
| |
| static void 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]; |
| |
| crypto_bignum_to_bin(element1, element_b1, sizeof(element_b1), |
| sae->tmp->prime_len); |
| crypto_bignum_to_bin(element2, element_b2, sizeof(element_b2), |
| sae->tmp->prime_len); |
| |
| sae_cn_confirm(sae, sc, scalar1, element_b1, sae->tmp->prime_len, |
| scalar2, element_b2, sae->tmp->prime_len, confirm); |
| } |
| |
| |
| void sae_write_confirm(struct sae_data *sae, struct wpabuf *buf) |
| { |
| const u8 *sc; |
| |
| if (sae->tmp == NULL) |
| return; |
| |
| /* 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, SHA256_MAC_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, SHA256_MAC_LEN)); |
| } |
| |
| |
| int sae_check_confirm(struct sae_data *sae, const u8 *data, size_t len) |
| { |
| u8 verifier[SHA256_MAC_LEN]; |
| |
| if (len < 2 + SHA256_MAC_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->tmp || !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) |
| return -1; |
| 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); |
| } else { |
| if (!sae->tmp->peer_commit_element_ffc || |
| !sae->tmp->own_commit_element_ffc) |
| return -1; |
| 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); |
| } |
| |
| if (os_memcmp_const(verifier, data + 2, SHA256_MAC_LEN) != 0) { |
| wpa_printf(MSG_DEBUG, "SAE: Confirm mismatch"); |
| wpa_hexdump(MSG_DEBUG, "SAE: Received confirm", |
| data + 2, SHA256_MAC_LEN); |
| wpa_hexdump(MSG_DEBUG, "SAE: Calculated verifier", |
| verifier, SHA256_MAC_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 "?"; |
| } |