SAE: Store PWE as EC point or bignum instead of octet string
This avoids unnecessary EC point and bignum initialization steps during the SAE exchange. Signed-hostap: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen
parent
b1677c393b
commit
4df61ba5b9
2 changed files with 43 additions and 62 deletions
102
src/common/sae.c
102
src/common/sae.c
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@ -73,6 +73,8 @@ void sae_clear_data(struct sae_data *sae)
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crypto_bignum_deinit(sae->prime_buf, 0);
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crypto_bignum_deinit(sae->order_buf, 0);
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crypto_bignum_deinit(sae->sae_rand, 1);
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crypto_bignum_deinit(sae->pwe_ffc, 1);
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crypto_ec_point_deinit(sae->pwe_ecc, 1);
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os_memset(sae, 0, sizeof(*sae));
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}
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@ -181,7 +183,7 @@ static void sae_pwd_seed_key(const u8 *addr1, const u8 *addr2, u8 *key)
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static int sae_test_pwd_seed(struct sae_data *sae, const u8 *pwd_seed,
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struct crypto_ec_point *pwe, u8 *pwe_bin)
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struct crypto_ec_point *pwe)
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{
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u8 pwd_value[SAE_MAX_PRIME_LEN], prime[SAE_MAX_PRIME_LEN];
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struct crypto_bignum *x;
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@ -220,21 +222,13 @@ static int sae_test_pwd_seed(struct sae_data *sae, const u8 *pwd_seed,
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wpa_printf(MSG_DEBUG, "SAE: PWE found");
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if (crypto_ec_point_to_bin(sae->ec, pwe, pwe_bin,
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pwe_bin + sae->prime_len) < 0)
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return -1;
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wpa_hexdump_key(MSG_DEBUG, "SAE: PWE x", pwe_bin, sae->prime_len);
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wpa_hexdump_key(MSG_DEBUG, "SAE: PWE y",
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pwe_bin + sae->prime_len, sae->prime_len);
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return 1;
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}
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static int sae_derive_pwe(struct sae_data *sae, const u8 *addr1,
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const u8 *addr2, const u8 *password,
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size_t password_len, struct crypto_ec_point *pwe,
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u8 *pwe_bin)
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size_t password_len)
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{
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u8 counter, k = 4;
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u8 addrs[2 * ETH_ALEN];
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@ -242,8 +236,12 @@ static int sae_derive_pwe(struct sae_data *sae, const u8 *addr1,
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size_t len[2];
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int found = 0;
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struct crypto_ec_point *pwe_tmp;
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u8 pwe_bin_tmp[2 * SAE_MAX_PRIME_LEN];
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if (sae->pwe_ecc == NULL) {
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sae->pwe_ecc = crypto_ec_point_init(sae->ec);
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if (sae->pwe_ecc == NULL)
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return -1;
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}
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pwe_tmp = crypto_ec_point_init(sae->ec);
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if (pwe_tmp == NULL)
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return -1;
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@ -283,8 +281,7 @@ static int sae_derive_pwe(struct sae_data *sae, const u8 *addr1,
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pwd_seed) < 0)
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break;
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res = sae_test_pwd_seed(sae, pwd_seed,
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found ? pwe_tmp : pwe,
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found ? pwe_bin_tmp : pwe_bin);
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found ? pwe_tmp : sae->pwe_ecc);
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if (res < 0)
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break;
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if (res == 0)
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@ -304,7 +301,7 @@ static int sae_derive_pwe(struct sae_data *sae, const u8 *addr1,
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}
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static int sae_derive_commit(struct sae_data *sae, struct crypto_ec_point *pwe)
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static int sae_derive_commit(struct sae_data *sae)
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{
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struct crypto_bignum *x, *mask;
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struct crypto_ec_point *elem;
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@ -330,7 +327,7 @@ static int sae_derive_commit(struct sae_data *sae, struct crypto_ec_point *pwe)
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sae->own_commit_scalar, sae->prime_len);
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/* COMMIT-ELEMENT = inverse(scalar-op(mask, PWE)) */
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if (crypto_ec_point_mul(sae->ec, pwe, mask, elem) < 0 ||
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if (crypto_ec_point_mul(sae->ec, sae->pwe_ecc, mask, elem) < 0 ||
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crypto_ec_point_invert(sae->ec, elem) < 0 ||
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crypto_ec_point_to_bin(sae->ec, elem, sae->own_commit_element,
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sae->own_commit_element + sae->prime_len) <
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@ -357,26 +354,17 @@ static int sae_prepare_commit_ec(const u8 *addr1, const u8 *addr2,
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const u8 *password, size_t password_len,
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struct sae_data *sae)
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{
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struct crypto_ec_point *pwe;
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int ret = 0;
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pwe = crypto_ec_point_init(sae->ec);
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if (pwe == NULL ||
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sae_derive_pwe(sae, addr1, addr2, password, password_len, pwe,
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sae->pwe) < 0 ||
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sae_derive_commit(sae, pwe) < 0)
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ret = -1;
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crypto_ec_point_deinit(pwe, 1);
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return ret;
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if (sae_derive_pwe(sae, addr1, addr2, password, password_len) < 0 ||
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sae_derive_commit(sae) < 0)
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return -1;
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return 0;
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}
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static int sae_test_pwd_seed_dh(struct sae_data *sae, const u8 *pwd_seed,
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struct crypto_bignum *pwe)
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{
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u8 pwd_value[SAE_MAX_PRIME_LEN];
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u8 pwd_value[SAE_MAX_PRIME_LEN], pwe_bin[SAE_MAX_PRIME_LEN];
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size_t bits = sae->prime_len * 8;
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u8 exp[1];
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struct crypto_bignum *a, *b;
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@ -434,16 +422,16 @@ static int sae_test_pwd_seed_dh(struct sae_data *sae, const u8 *pwd_seed,
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return -1;
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}
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res = crypto_bignum_to_bin(pwe, sae->pwe, sizeof(sae->pwe),
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res = crypto_bignum_to_bin(pwe, pwe_bin, sizeof(pwe_bin),
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sae->prime_len);
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if (res < 0) {
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wpa_printf(MSG_DEBUG, "SAE: Not room for PWE");
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return -1;
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}
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wpa_hexdump_key(MSG_DEBUG, "SAE: PWE candidate", sae->pwe, res);
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wpa_hexdump_key(MSG_DEBUG, "SAE: PWE candidate", pwe_bin, res);
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/* if (PWE > 1) --> found */
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if (val_zero_or_one(sae->pwe, sae->prime_len)) {
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if (val_zero_or_one(pwe_bin, sae->prime_len)) {
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wpa_printf(MSG_DEBUG, "SAE: PWE <= 1");
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return 0;
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}
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@ -455,7 +443,7 @@ static int sae_test_pwd_seed_dh(struct sae_data *sae, const u8 *pwd_seed,
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static int sae_derive_pwe_dh(struct sae_data *sae, const u8 *addr1,
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const u8 *addr2, const u8 *password,
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size_t password_len, struct crypto_bignum *pwe)
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size_t password_len)
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{
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u8 counter;
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u8 addrs[2 * ETH_ALEN];
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@ -463,6 +451,12 @@ static int sae_derive_pwe_dh(struct sae_data *sae, const u8 *addr1,
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size_t len[2];
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int found = 0;
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if (sae->pwe_ffc == NULL) {
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sae->pwe_ffc = crypto_bignum_init();
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if (sae->pwe_ffc == NULL)
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return -1;
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}
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wpa_hexdump_ascii_key(MSG_DEBUG, "SAE: password",
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password, password_len);
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@ -492,7 +486,7 @@ static int sae_derive_pwe_dh(struct sae_data *sae, const u8 *addr1,
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if (hmac_sha256_vector(addrs, sizeof(addrs), 2, addr, len,
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pwd_seed) < 0)
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break;
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res = sae_test_pwd_seed_dh(sae, pwd_seed, pwe);
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res = sae_test_pwd_seed_dh(sae, pwd_seed, sae->pwe_ffc);
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if (res < 0)
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break;
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if (res > 0) {
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@ -505,7 +499,7 @@ static int sae_derive_pwe_dh(struct sae_data *sae, const u8 *addr1,
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}
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static int sae_derive_commit_dh(struct sae_data *sae, struct crypto_bignum *pwe)
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static int sae_derive_commit_dh(struct sae_data *sae)
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{
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struct crypto_bignum *x, *mask, *elem;
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int ret = -1;
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@ -530,7 +524,7 @@ static int sae_derive_commit_dh(struct sae_data *sae, struct crypto_bignum *pwe)
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sae->own_commit_scalar, sae->prime_len);
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/* COMMIT-ELEMENT = inverse(scalar-op(mask, PWE)) */
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if (crypto_bignum_exptmod(pwe, mask, sae->prime, elem) < 0 ||
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if (crypto_bignum_exptmod(sae->pwe_ffc, mask, sae->prime, elem) < 0 ||
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crypto_bignum_inverse(elem, sae->prime, elem) < 0 ||
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crypto_bignum_to_bin(elem, sae->own_commit_element,
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sizeof(sae->own_commit_element),
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@ -555,19 +549,10 @@ static int sae_prepare_commit_dh(const u8 *addr1, const u8 *addr2,
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const u8 *password, size_t password_len,
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struct sae_data *sae)
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{
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struct crypto_bignum *pwe;
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int ret = 0;
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pwe = crypto_bignum_init();
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if (pwe == NULL ||
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sae_derive_pwe_dh(sae, addr1, addr2, password, password_len, pwe) <
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0 ||
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sae_derive_commit_dh(sae, pwe) < 0)
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ret = -1;
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crypto_bignum_deinit(pwe, 1);
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return ret;
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if (sae_derive_pwe_dh(sae, addr1, addr2, password, password_len) < 0 ||
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sae_derive_commit_dh(sae) < 0)
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return -1;
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return 0;
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}
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@ -631,17 +616,15 @@ static int sae_check_peer_commit(struct sae_data *sae)
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static int sae_derive_k_ec(struct sae_data *sae, u8 *k)
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{
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struct crypto_ec_point *pwe, *peer_elem, *K;
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struct crypto_ec_point *peer_elem, *K;
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struct crypto_bignum *peer_scalar;
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int ret = -1;
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pwe = crypto_ec_point_from_bin(sae->ec, sae->pwe);
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peer_scalar = crypto_bignum_init_set(sae->peer_commit_scalar,
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sae->prime_len);
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peer_elem = crypto_ec_point_from_bin(sae->ec, sae->peer_commit_element);
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K = crypto_ec_point_init(sae->ec);
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if (pwe == NULL || peer_elem == NULL || peer_scalar == NULL ||
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K == NULL)
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if (peer_elem == NULL || peer_scalar == NULL || K == NULL)
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goto fail;
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if (!crypto_ec_point_is_on_curve(sae->ec, peer_elem)) {
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@ -656,7 +639,7 @@ static int sae_derive_k_ec(struct sae_data *sae, u8 *k)
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* k = F(K) (= x coordinate)
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*/
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if (crypto_ec_point_mul(sae->ec, pwe, peer_scalar, K) < 0 ||
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if (crypto_ec_point_mul(sae->ec, sae->pwe_ecc, peer_scalar, K) < 0 ||
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crypto_ec_point_add(sae->ec, K, peer_elem, K) < 0 ||
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crypto_ec_point_mul(sae->ec, K, sae->sae_rand, K) < 0 ||
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crypto_ec_point_is_at_infinity(sae->ec, K) ||
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@ -669,7 +652,6 @@ static int sae_derive_k_ec(struct sae_data *sae, u8 *k)
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ret = 0;
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fail:
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crypto_ec_point_deinit(pwe, 1);
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crypto_ec_point_deinit(peer_elem, 0);
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crypto_ec_point_deinit(K, 1);
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return ret;
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@ -678,17 +660,15 @@ fail:
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static int sae_derive_k_dh(struct sae_data *sae, u8 *k)
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{
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struct crypto_bignum *pwe, *peer_elem, *K, *peer_scalar;
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struct crypto_bignum *peer_elem, *K, *peer_scalar;
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int ret = -1;
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pwe = crypto_bignum_init_set(sae->pwe, sae->prime_len);
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peer_scalar = crypto_bignum_init_set(sae->peer_commit_scalar,
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sae->prime_len);
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peer_elem = crypto_bignum_init_set(sae->peer_commit_element,
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sae->prime_len);
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K = crypto_bignum_init();
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if (pwe == NULL || peer_elem == NULL || peer_scalar == NULL ||
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K == NULL)
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if (peer_elem == NULL || peer_scalar == NULL || K == NULL)
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goto fail;
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/*
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@ -698,7 +678,8 @@ static int sae_derive_k_dh(struct sae_data *sae, u8 *k)
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* k = F(K) (= x coordinate)
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*/
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if (crypto_bignum_exptmod(pwe, peer_scalar, sae->prime, K) < 0 ||
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if (crypto_bignum_exptmod(sae->pwe_ffc, peer_scalar, sae->prime, K) < 0
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crypto_bignum_mulmod(K, peer_elem, sae->prime, K) < 0 ||
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crypto_bignum_exptmod(K, sae->sae_rand, sae->prime, K) < 0 ||
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crypto_bignum_to_bin(K, k, SAE_MAX_PRIME_LEN, sae->prime_len) < 0 ||
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@ -711,7 +692,6 @@ static int sae_derive_k_dh(struct sae_data *sae, u8 *k)
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ret = 0;
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fail:
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crypto_bignum_deinit(pwe, 1);
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crypto_bignum_deinit(peer_elem, 0);
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crypto_bignum_deinit(K, 1);
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return ret;
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@ -26,7 +26,8 @@ struct sae_data {
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u8 own_commit_element[2 * SAE_MAX_PRIME_LEN];
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u8 peer_commit_scalar[SAE_MAX_PRIME_LEN];
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u8 peer_commit_element[2 * SAE_MAX_PRIME_LEN];
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u8 pwe[2 * SAE_MAX_PRIME_LEN];
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struct crypto_ec_point *pwe_ecc;
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struct crypto_bignum *pwe_ffc;
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struct crypto_bignum *sae_rand;
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int group;
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struct crypto_ec *ec;
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