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SAE: Reject FFC commit-element with value p-1

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The current P802.11 description of SAE uses "1 < element < p" as the
required range. However, this is not correct and does not match the
Dragonfly description of "1 < element < p-1". SAE definition will need
to change here. Update the implementation to reject p-1 based on the
correct rule here.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2015-06-27 21:20:14 +03:00
parent fee39910ee
commit 575e4f5d49
1 changed files with 13 additions and 7 deletions
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20
src/common/sae.c
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@ -1037,7 +1037,8 @@ static u16 sae_parse_commit_element_ecc(struct sae_data *sae, const u8 *pos,
static u16 sae_parse_commit_element_ffc(struct sae_data *sae, const u8 *pos, static u16 sae_parse_commit_element_ffc(struct sae_data *sae, const u8 *pos,
const u8 *end) const u8 *end)
{ {
struct crypto_bignum *res; struct crypto_bignum *res, *one;
const u8 one_bin[1] = { 0x01 };
if (pos + sae->tmp->prime_len > end) { if (pos + sae->tmp->prime_len > end) {
wpa_printf(MSG_DEBUG, "SAE: Not enough data for " wpa_printf(MSG_DEBUG, "SAE: Not enough data for "
@ -1052,18 +1053,23 @@ static u16 sae_parse_commit_element_ffc(struct sae_data *sae, const u8 *pos,
crypto_bignum_init_set(pos, sae->tmp->prime_len); crypto_bignum_init_set(pos, sae->tmp->prime_len);
if (sae->tmp->peer_commit_element_ffc == NULL) if (sae->tmp->peer_commit_element_ffc == NULL)
return WLAN_STATUS_UNSPECIFIED_FAILURE; return WLAN_STATUS_UNSPECIFIED_FAILURE;
if (crypto_bignum_is_zero(sae->tmp->peer_commit_element_ffc) || /* 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_is_one(sae->tmp->peer_commit_element_ffc) ||
crypto_bignum_cmp(sae->tmp->peer_commit_element_ffc, crypto_bignum_cmp(sae->tmp->peer_commit_element_ffc, res) >= 0) {
sae->tmp->prime) >= 0) { crypto_bignum_deinit(res, 0);
crypto_bignum_deinit(one, 0);
wpa_printf(MSG_DEBUG, "SAE: Invalid peer element"); wpa_printf(MSG_DEBUG, "SAE: Invalid peer element");
return WLAN_STATUS_UNSPECIFIED_FAILURE; return WLAN_STATUS_UNSPECIFIED_FAILURE;
} }
crypto_bignum_deinit(one, 0);
/* scalar-op(r, ELEMENT) = 1 modulo p */ /* scalar-op(r, ELEMENT) = 1 modulo p */
res = crypto_bignum_init(); if (crypto_bignum_exptmod(sae->tmp->peer_commit_element_ffc,
if (res == NULL ||
crypto_bignum_exptmod(sae->tmp->peer_commit_element_ffc,
sae->tmp->order, sae->tmp->prime, res) < 0 || sae->tmp->order, sae->tmp->prime, res) < 0 ||
!crypto_bignum_is_one(res)) { !crypto_bignum_is_one(res)) {
wpa_printf(MSG_DEBUG, "SAE: Invalid peer element (scalar-op)"); wpa_printf(MSG_DEBUG, "SAE: Invalid peer element (scalar-op)");