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SAE: Check SHA256-PRF operation result

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While this is mostly theoretical, check explicitly that SHA256
operations in sha256_prf*() succeed.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2016-03-27 21:43:24 +03:00
parent ea86a34667
commit 0741c481ee
3 changed files with 34 additions and 23 deletions
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19
src/common/sae.c
View File

@ -1,6 +1,6 @@
/*
* Simultaneous authentication of equals
* Copyright (c) 2012-2015, Jouni Malinen <j@w1.fi>
* 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.
@ -275,8 +275,9 @@ static int sae_test_pwd_seed_ecc(struct sae_data *sae, const u8 *pwd_seed,
/* pwd-value = KDF-z(pwd-seed, "SAE Hunting and Pecking", p) */
bits = crypto_ec_prime_len_bits(sae->tmp->ec);
sha256_prf_bits(pwd_seed, SHA256_MAC_LEN, "SAE Hunting and Pecking",
prime, sae->tmp->prime_len, pwd_value, bits);
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, sizeof(pwd_value), 8 - bits % 8);
wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value",
@ -318,9 +319,10 @@ static int sae_test_pwd_seed_ffc(struct sae_data *sae, const u8 *pwd_seed,
wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-seed", pwd_seed, SHA256_MAC_LEN);
/* pwd-value = KDF-z(pwd-seed, "SAE Hunting and Pecking", p) */
sha256_prf_bits(pwd_seed, SHA256_MAC_LEN, "SAE Hunting and Pecking",
sae->tmp->dh->prime, sae->tmp->prime_len, pwd_value,
bits);
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);
@ -809,8 +811,9 @@ static int sae_derive_keys(struct sae_data *sae, const u8 *k)
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);
sha256_prf(keyseed, sizeof(keyseed), "SAE KCK and PMK",
val, sae->tmp->prime_len, keys, sizeof(keys));
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);

26
src/crypto/sha256-prf.c
View File

@ -1,6 +1,6 @@
/*
* SHA256-based PRF (IEEE 802.11r)
* Copyright (c) 2003-2013, Jouni Malinen <j@w1.fi>
* Copyright (c) 2003-2016, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
@ -22,14 +22,16 @@
* @data_len: Length of the data
* @buf: Buffer for the generated pseudo-random key
* @buf_len: Number of bytes of key to generate
* Returns: 0 on success, -1 on failure
*
* This function is used to derive new, cryptographically separate keys from a
* given key.
*/
void sha256_prf(const u8 *key, size_t key_len, const char *label,
int sha256_prf(const u8 *key, size_t key_len, const char *label,
const u8 *data, size_t data_len, u8 *buf, size_t buf_len)
{
sha256_prf_bits(key, key_len, label, data, data_len, buf, buf_len * 8);
return sha256_prf_bits(key, key_len, label, data, data_len, buf,
buf_len * 8);
}
@ -42,15 +44,16 @@ void sha256_prf(const u8 *key, size_t key_len, const char *label,
* @data_len: Length of the data
* @buf: Buffer for the generated pseudo-random key
* @buf_len: Number of bits of key to generate
* Returns: 0 on success, -1 on failure
*
* This function is used to derive new, cryptographically separate keys from a
* given key. If the requested buf_len is not divisible by eight, the least
* significant 1-7 bits of the last octet in the output are not part of the
* requested output.
*/
void sha256_prf_bits(const u8 *key, size_t key_len, const char *label,
const u8 *data, size_t data_len, u8 *buf,
size_t buf_len_bits)
int sha256_prf_bits(const u8 *key, size_t key_len, const char *label,
const u8 *data, size_t data_len, u8 *buf,
size_t buf_len_bits)
{
u16 counter = 1;
size_t pos, plen;
@ -75,11 +78,14 @@ void sha256_prf_bits(const u8 *key, size_t key_len, const char *label,
plen = buf_len - pos;
WPA_PUT_LE16(counter_le, counter);
if (plen >= SHA256_MAC_LEN) {
hmac_sha256_vector(key, key_len, 4, addr, len,
&buf[pos]);
if (hmac_sha256_vector(key, key_len, 4, addr, len,
&buf[pos]) < 0)
return -1;
pos += SHA256_MAC_LEN;
} else {
hmac_sha256_vector(key, key_len, 4, addr, len, hash);
if (hmac_sha256_vector(key, key_len, 4, addr, len,
hash) < 0)
return -1;
os_memcpy(&buf[pos], hash, plen);
pos += plen;
break;
@ -97,4 +103,6 @@ void sha256_prf_bits(const u8 *key, size_t key_len, const char *label,
}
os_memset(hash, 0, sizeof(hash));
return 0;
}

12
src/crypto/sha256.h
View File

@ -1,6 +1,6 @@
/*
* SHA256 hash implementation and interface functions
* Copyright (c) 2003-2014, Jouni Malinen <j@w1.fi>
* Copyright (c) 2003-2016, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
@ -15,11 +15,11 @@ int hmac_sha256_vector(const u8 *key, size_t key_len, size_t num_elem,
const u8 *addr[], const size_t *len, u8 *mac);
int hmac_sha256(const u8 *key, size_t key_len, const u8 *data,
size_t data_len, u8 *mac);
void sha256_prf(const u8 *key, size_t key_len, const char *label,
const u8 *data, size_t data_len, u8 *buf, size_t buf_len);
void sha256_prf_bits(const u8 *key, size_t key_len, const char *label,
const u8 *data, size_t data_len, u8 *buf,
size_t buf_len_bits);
int sha256_prf(const u8 *key, size_t key_len, const char *label,
const u8 *data, size_t data_len, u8 *buf, size_t buf_len);
int sha256_prf_bits(const u8 *key, size_t key_len, const char *label,
const u8 *data, size_t data_len, u8 *buf,
size_t buf_len_bits);
void tls_prf_sha256(const u8 *secret, size_t secret_len,
const char *label, const u8 *seed, size_t seed_len,
u8 *out, size_t outlen);