mirror of
https://github.com/vanhoefm/fragattacks.git
synced 2024-11-28 10:18:21 -05:00
SAE: Add generation of the commit message fields
This adds derivation of PWE and the needed commit values so that the full SAE commit message can be built. Signed-hostap: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen
parent
750efe6ea6
commit
8e31e9550a
@ -202,6 +202,7 @@ endif
|
||||
|
||||
ifdef CONFIG_SAE
|
||||
L_CFLAGS += -DCONFIG_SAE
|
||||
OBJS += src/common/sae.c
|
||||
endif
|
||||
|
||||
ifdef CONFIG_IEEE80211N
|
||||
|
||||
@ -174,6 +174,7 @@ endif
|
||||
|
||||
ifdef CONFIG_SAE
|
||||
CFLAGS += -DCONFIG_SAE
|
||||
OBJS += ../src/common/sae.o
|
||||
endif
|
||||
|
||||
ifdef CONFIG_WNM
|
||||
|
||||
@ -323,14 +323,18 @@ static struct wpabuf * auth_build_sae_commit(struct hostapd_data *hapd,
|
||||
{
|
||||
struct wpabuf *buf;
|
||||
|
||||
buf = wpabuf_alloc(2);
|
||||
if (sae_prepare_commit(hapd->own_addr, sta->addr,
|
||||
(u8 *) hapd->conf->ssid.wpa_passphrase,
|
||||
os_strlen(hapd->conf->ssid.wpa_passphrase),
|
||||
sta->sae) < 0) {
|
||||
wpa_printf(MSG_DEBUG, "SAE: Could not pick PWE");
|
||||
return NULL;
|
||||
}
|
||||
|
||||
buf = wpabuf_alloc(SAE_COMMIT_MAX_LEN);
|
||||
if (buf == NULL)
|
||||
return NULL;
|
||||
|
||||
wpabuf_put_le16(buf, 19); /* Finite Cyclic Group */
|
||||
/* TODO: Anti-Clogging Token (if requested) */
|
||||
/* TODO: Scalar */
|
||||
/* TODO: Element */
|
||||
sae_write_commit(sta->sae, buf);
|
||||
|
||||
return buf;
|
||||
}
|
||||
|
||||
311
src/common/sae.c
Normal file
311
src/common/sae.c
Normal file
@ -0,0 +1,311 @@
|
||||
/*
|
||||
* Simultaneous authentication of equals
|
||||
* Copyright (c) 2012, 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"
|
||||
/* TODO: move OpenSSL dependencies into crypto/crypto_openssl.c */
|
||||
#include <openssl/bn.h>
|
||||
#include <openssl/ec.h>
|
||||
#include <openssl/obj_mac.h>
|
||||
|
||||
#include "common.h"
|
||||
#include "crypto/sha256.h"
|
||||
#include "crypto/random.h"
|
||||
#include "sae.h"
|
||||
|
||||
|
||||
static const u8 group19_prime[] = {
|
||||
0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x01,
|
||||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
||||
0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF,
|
||||
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
|
||||
};
|
||||
|
||||
static const u8 group19_order[] = {
|
||||
0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00,
|
||||
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
|
||||
0xBC, 0xE6, 0xFA, 0xAD, 0xA7, 0x17, 0x9E, 0x84,
|
||||
0xF3, 0xB9, 0xCA, 0xC2, 0xFC, 0x63, 0x25, 0x51
|
||||
};
|
||||
|
||||
|
||||
static int val_zero_or_one(const u8 *val, size_t len)
|
||||
{
|
||||
size_t i;
|
||||
|
||||
for (i = 0; i < len - 1; i++) {
|
||||
if (val[i])
|
||||
return 0;
|
||||
}
|
||||
|
||||
return val[len - 1] <= 1;
|
||||
}
|
||||
|
||||
|
||||
static int sae_get_rand(u8 *val)
|
||||
{
|
||||
int iter = 0;
|
||||
|
||||
do {
|
||||
if (random_get_bytes(val, sizeof(group19_prime)) < 0)
|
||||
return -1;
|
||||
if (iter++ > 100)
|
||||
return -1;
|
||||
} while (os_memcmp(val, group19_order, sizeof(group19_prime)) >= 0 ||
|
||||
val_zero_or_one(val, sizeof(group19_prime)));
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
static void sae_bn_to_bin(const BIGNUM *bn, u8 *bin, size_t len)
|
||||
{
|
||||
int offset = len - BN_num_bytes(bn);
|
||||
os_memset(bin, 0, offset);
|
||||
BN_bn2bin(bn, bin + offset);
|
||||
}
|
||||
|
||||
|
||||
static int sae_ec_point_to_bin(BN_CTX *bnctx, EC_GROUP *group, EC_POINT *point,
|
||||
u8 *bin)
|
||||
{
|
||||
BIGNUM *x, *y;
|
||||
int ret = -1;
|
||||
|
||||
x = BN_new();
|
||||
y = BN_new();
|
||||
|
||||
if (x && y &&
|
||||
EC_POINT_get_affine_coordinates_GFp(group, point, x, y, bnctx)) {
|
||||
sae_bn_to_bin(x, bin, 32);
|
||||
sae_bn_to_bin(y, bin + 32, 32);
|
||||
ret = 0;
|
||||
}
|
||||
|
||||
BN_free(x);
|
||||
BN_free(y);
|
||||
return ret;
|
||||
}
|
||||
|
||||
|
||||
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(BN_CTX *bnctx, EC_GROUP *group, const u8 *pwd_seed,
|
||||
EC_POINT *pwe, u8 *pwe_bin)
|
||||
{
|
||||
u8 pwd_value[32];
|
||||
BIGNUM *x;
|
||||
int y_bit;
|
||||
|
||||
wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-seed", pwd_seed, 32);
|
||||
|
||||
/* pwd-value = KDF-z(pwd-seed, "SAE Hunting and Pecking", p) */
|
||||
sha256_prf(pwd_seed, 32, "SAE Hunting and Pecking",
|
||||
group19_prime, sizeof(group19_prime),
|
||||
pwd_value, sizeof(pwd_value));
|
||||
wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value",
|
||||
pwd_value, sizeof(pwd_value));
|
||||
|
||||
if (os_memcmp(pwd_value, group19_prime, sizeof(group19_prime)) >= 0)
|
||||
return 0;
|
||||
|
||||
y_bit = pwd_seed[SHA256_MAC_LEN - 1] & 0x01;
|
||||
|
||||
x = BN_bin2bn(pwd_value, sizeof(pwd_value), NULL);
|
||||
if (x == NULL)
|
||||
return -1;
|
||||
if (!EC_POINT_set_compressed_coordinates_GFp(group, pwe, x, y_bit,
|
||||
bnctx) ||
|
||||
!EC_POINT_is_on_curve(group, pwe, bnctx)) {
|
||||
BN_free(x);
|
||||
wpa_printf(MSG_DEBUG, "SAE: No solution found");
|
||||
return 0;
|
||||
}
|
||||
BN_free(x);
|
||||
|
||||
wpa_printf(MSG_DEBUG, "SAE: PWE found");
|
||||
|
||||
if (sae_ec_point_to_bin(bnctx, group, pwe, pwe_bin) < 0)
|
||||
return -1;
|
||||
|
||||
wpa_hexdump_key(MSG_DEBUG, "SAE: PWE x", pwe_bin, 32);
|
||||
wpa_hexdump_key(MSG_DEBUG, "SAE: PWE y", pwe_bin + 32, 32);
|
||||
return 1;
|
||||
}
|
||||
|
||||
|
||||
static int sae_derive_pwe(BN_CTX *bnctx, EC_GROUP *group, const u8 *addr1,
|
||||
const u8 *addr2, const u8 *password,
|
||||
size_t password_len, EC_POINT *pwe, u8 *pwe_bin)
|
||||
{
|
||||
u8 counter, k = 4;
|
||||
u8 addrs[2 * ETH_ALEN];
|
||||
const u8 *addr[2];
|
||||
size_t len[2];
|
||||
int found = 0;
|
||||
EC_POINT *pwe_tmp;
|
||||
u8 pwe_bin_tmp[2 * 32];
|
||||
|
||||
pwe_tmp = EC_POINT_new(group);
|
||||
if (pwe_tmp == NULL)
|
||||
return -1;
|
||||
|
||||
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 || counter)
|
||||
*/
|
||||
sae_pwd_seed_key(addr1, addr2, addrs);
|
||||
|
||||
addr[0] = password;
|
||||
len[0] = password_len;
|
||||
addr[1] = &counter;
|
||||
len[1] = sizeof(counter);
|
||||
|
||||
/*
|
||||
* 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];
|
||||
int res;
|
||||
|
||||
wpa_printf(MSG_DEBUG, "SAE: counter = %u", counter);
|
||||
if (hmac_sha256_vector(addrs, sizeof(addrs), 2, addr, len,
|
||||
pwd_seed) < 0)
|
||||
break;
|
||||
res = sae_test_pwd_seed(bnctx, group, pwd_seed,
|
||||
found ? pwe_tmp : pwe,
|
||||
found ? pwe_bin_tmp : pwe_bin);
|
||||
if (res < 0)
|
||||
break;
|
||||
if (res == 0)
|
||||
continue;
|
||||
if (found) {
|
||||
wpa_printf(MSG_DEBUG, "SAE: Ignore this PWE (one was "
|
||||
"already selected)");
|
||||
} else {
|
||||
wpa_printf(MSG_DEBUG, "SAE: Use this PWE");
|
||||
found = 1;
|
||||
}
|
||||
|
||||
if (counter > 200) {
|
||||
/* This should not happen in practice */
|
||||
wpa_printf(MSG_DEBUG, "SAE: Failed to derive PWE");
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
EC_POINT_clear_free(pwe_tmp);
|
||||
|
||||
return found ? 0 : -1;
|
||||
}
|
||||
|
||||
|
||||
static int sae_derive_commit(struct sae_data *sae, BN_CTX *bnctx,
|
||||
EC_GROUP *group, EC_POINT *pwe)
|
||||
{
|
||||
BIGNUM *x, *bn_rand, *bn_mask, *order;
|
||||
EC_POINT *elem;
|
||||
u8 mask[32];
|
||||
int ret = -1;
|
||||
|
||||
if (sae_get_rand(sae->sae_rand) < 0 || sae_get_rand(mask) < 0)
|
||||
return -1;
|
||||
wpa_hexdump_key(MSG_DEBUG, "SAE: rand",
|
||||
sae->sae_rand, sizeof(sae->sae_rand));
|
||||
wpa_hexdump_key(MSG_DEBUG, "SAE: mask", mask, sizeof(mask));
|
||||
|
||||
x = BN_new();
|
||||
bn_rand = BN_bin2bn(sae->sae_rand, 32, NULL);
|
||||
bn_mask = BN_bin2bn(mask, sizeof(mask), NULL);
|
||||
order = BN_bin2bn(group19_order, sizeof(group19_order), NULL);
|
||||
elem = EC_POINT_new(group);
|
||||
if (x == NULL || bn_rand == NULL || bn_mask == NULL || order == NULL ||
|
||||
elem == NULL)
|
||||
goto fail;
|
||||
|
||||
/* commit-scalar = (rand + mask) modulo r */
|
||||
BN_add(x, bn_rand, bn_mask);
|
||||
BN_mod(x, x, order, bnctx);
|
||||
sae_bn_to_bin(x, sae->own_commit_scalar, 32);
|
||||
wpa_hexdump(MSG_DEBUG, "SAE: commit-scalar",
|
||||
sae->own_commit_scalar, 32);
|
||||
|
||||
/* COMMIT-ELEMENT = inverse(scalar-op(mask, PWE)) */
|
||||
if (!EC_POINT_mul(group, elem, NULL, pwe, bn_mask, bnctx) ||
|
||||
!EC_POINT_invert(group, elem, bnctx) ||
|
||||
sae_ec_point_to_bin(bnctx, group, elem, sae->own_commit_element) <
|
||||
0)
|
||||
goto fail;
|
||||
|
||||
wpa_hexdump(MSG_DEBUG, "SAE: commit-element x",
|
||||
sae->own_commit_element, 32);
|
||||
wpa_hexdump(MSG_DEBUG, "SAE: commit-element y",
|
||||
sae->own_commit_element + 32, 32);
|
||||
|
||||
ret = 0;
|
||||
fail:
|
||||
EC_POINT_free(elem);
|
||||
BN_free(order);
|
||||
BN_clear_free(bn_mask);
|
||||
os_memset(mask, 0, sizeof(mask));
|
||||
BN_clear_free(bn_rand);
|
||||
BN_clear_free(x);
|
||||
return ret;
|
||||
}
|
||||
|
||||
|
||||
int sae_prepare_commit(const u8 *addr1, const u8 *addr2,
|
||||
const u8 *password, size_t password_len,
|
||||
struct sae_data *sae)
|
||||
{
|
||||
BN_CTX *bnctx;
|
||||
EC_POINT *pwe;
|
||||
EC_GROUP *group;
|
||||
int ret = 0;
|
||||
|
||||
bnctx = BN_CTX_new();
|
||||
group = EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1);
|
||||
pwe = EC_POINT_new(group);
|
||||
if (bnctx == NULL || group == NULL || pwe == NULL ||
|
||||
sae_derive_pwe(bnctx, group, addr1, addr2, password, password_len,
|
||||
pwe, sae->pwe) < 0 ||
|
||||
sae_derive_commit(sae, bnctx, group, pwe) < 0)
|
||||
ret = -1;
|
||||
|
||||
EC_POINT_clear_free(pwe);
|
||||
EC_GROUP_free(group);
|
||||
BN_CTX_free(bnctx);
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
|
||||
void sae_write_commit(struct sae_data *sae, struct wpabuf *buf)
|
||||
{
|
||||
wpabuf_put_le16(buf, 19); /* Finite Cyclic Group */
|
||||
/* TODO: Anti-Clogging Token (if requested) */
|
||||
wpabuf_put_data(buf, sae->own_commit_scalar, 32);
|
||||
wpabuf_put_data(buf, sae->own_commit_element, 2 * 32);
|
||||
}
|
||||
@ -9,9 +9,20 @@
|
||||
#ifndef SAE_H
|
||||
#define SAE_H
|
||||
|
||||
#define SAE_COMMIT_MAX_LEN (2 + 3 * 32)
|
||||
|
||||
struct sae_data {
|
||||
enum { SAE_INIT, SAE_COMMIT, SAE_CONFIRM } state;
|
||||
u16 send_confirm;
|
||||
u8 own_commit_scalar[32];
|
||||
u8 own_commit_element[2 * 32];
|
||||
u8 pwe[2 * 32];
|
||||
u8 sae_rand[32];
|
||||
};
|
||||
|
||||
int sae_prepare_commit(const u8 *addr1, const u8 *addr2,
|
||||
const u8 *password, size_t password_len,
|
||||
struct sae_data *sae);
|
||||
void sae_write_commit(struct sae_data *sae, struct wpabuf *buf);
|
||||
|
||||
#endif /* SAE_H */
|
||||
|
||||
@ -181,6 +181,7 @@ endif
|
||||
|
||||
ifdef CONFIG_SAE
|
||||
L_CFLAGS += -DCONFIG_SAE
|
||||
OBJS += src/common/sae.c
|
||||
endif
|
||||
|
||||
ifdef CONFIG_TDLS
|
||||
|
||||
@ -174,6 +174,7 @@ endif
|
||||
|
||||
ifdef CONFIG_SAE
|
||||
CFLAGS += -DCONFIG_SAE
|
||||
OBJS += ../src/common/sae.o
|
||||
endif
|
||||
|
||||
ifdef CONFIG_WNM
|
||||
|
||||
@ -1,6 +1,6 @@
|
||||
/*
|
||||
* wpa_supplicant - SME
|
||||
* Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi>
|
||||
* Copyright (c) 2009-2012, Jouni Malinen <j@w1.fi>
|
||||
*
|
||||
* This software may be distributed under the terms of the BSD license.
|
||||
* See README for more details.
|
||||
@ -42,20 +42,32 @@ static void sme_stop_sa_query(struct wpa_supplicant *wpa_s);
|
||||
|
||||
#ifdef CONFIG_SAE
|
||||
|
||||
static struct wpabuf * sme_auth_build_sae_commit(struct wpa_supplicant *wpa_s)
|
||||
static struct wpabuf * sme_auth_build_sae_commit(struct wpa_supplicant *wpa_s,
|
||||
struct wpa_ssid *ssid,
|
||||
const u8 *bssid)
|
||||
{
|
||||
struct wpabuf *buf;
|
||||
|
||||
buf = wpabuf_alloc(4 + 2);
|
||||
if (ssid->passphrase == NULL) {
|
||||
wpa_printf(MSG_DEBUG, "SAE: No password available");
|
||||
return NULL;
|
||||
}
|
||||
|
||||
if (sae_prepare_commit(wpa_s->own_addr, bssid,
|
||||
(u8 *) ssid->passphrase,
|
||||
os_strlen(ssid->passphrase),
|
||||
&wpa_s->sme.sae) < 0) {
|
||||
wpa_printf(MSG_DEBUG, "SAE: Could not pick PWE");
|
||||
return NULL;
|
||||
}
|
||||
|
||||
buf = wpabuf_alloc(4 + SAE_COMMIT_MAX_LEN);
|
||||
if (buf == NULL)
|
||||
return NULL;
|
||||
|
||||
wpabuf_put_le16(buf, 1); /* Transaction seq# */
|
||||
wpabuf_put_le16(buf, WLAN_STATUS_SUCCESS);
|
||||
wpabuf_put_le16(buf, 19); /* Finite Cyclic Group */
|
||||
/* TODO: Anti-Clogging Token (if requested) */
|
||||
/* TODO: Scalar */
|
||||
/* TODO: Element */
|
||||
sae_write_commit(&wpa_s->sme.sae, buf);
|
||||
|
||||
return buf;
|
||||
}
|
||||
@ -326,7 +338,8 @@ static void sme_send_authentication(struct wpa_supplicant *wpa_s,
|
||||
#ifdef CONFIG_SAE
|
||||
if (params.auth_alg == WPA_AUTH_ALG_SAE) {
|
||||
if (start)
|
||||
resp = sme_auth_build_sae_commit(wpa_s);
|
||||
resp = sme_auth_build_sae_commit(wpa_s, ssid,
|
||||
bss->bssid);
|
||||
else
|
||||
resp = sme_auth_build_sae_confirm(wpa_s);
|
||||
if (resp == NULL)
|
||||
|
||||
Loading…
Reference in New Issue
Block a user