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SAE: Implement hash-to-element PT/PWE crypto routines

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Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
This commit is contained in:
Jouni Malinen 2019-08-27 16:33:15 +03:00 committed by Jouni Malinen
parent ecd7114072
commit aeb022f8e5
2 changed files with 827 additions and 3 deletions
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804
src/common/sae.c
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@ -12,6 +12,8 @@
#include "utils/const_time.h"
#include "crypto/crypto.h"
#include "crypto/sha256.h"
#include "crypto/sha384.h"
#include "crypto/sha512.h"
#include "crypto/random.h"
#include "crypto/dh_groups.h"
#include "ieee802_11_defs.h"
@ -107,6 +109,7 @@ void sae_clear_temp_data(struct sae_data *sae)
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);
wpabuf_free(tmp->own_rejected_groups);
wpabuf_free(tmp->peer_rejected_groups);
os_free(tmp->pw_id);
bin_clear_free(tmp, sizeof(*tmp));
@ -526,6 +529,745 @@ fail:
}
static int hkdf_extract(size_t hash_len, const u8 *salt, size_t salt_len,
size_t num_elem, const u8 *addr[], const size_t len[],
u8 *prk)
{
if (hash_len == 32)
return hmac_sha256_vector(salt, salt_len, num_elem, addr, len,
prk);
#ifdef CONFIG_SHA384
if (hash_len == 48)
return hmac_sha384_vector(salt, salt_len, num_elem, addr, len,
prk);
#endif /* CONFIG_SHA384 */
#ifdef CONFIG_SHA512
if (hash_len == 64)
return hmac_sha512_vector(salt, salt_len, num_elem, addr, len,
prk);
#endif /* CONFIG_SHA512 */
return -1;
}
static int hkdf_expand(size_t hash_len, const u8 *prk, size_t prk_len,
const char *info, u8 *okm, size_t okm_len)
{
size_t info_len = os_strlen(info);
if (hash_len == 32)
return hmac_sha256_kdf(prk, prk_len, NULL,
(const u8 *) info, info_len,
okm, okm_len);
#ifdef CONFIG_SHA384
if (hash_len == 48)
return hmac_sha384_kdf(prk, prk_len, NULL,
(const u8 *) info, info_len,
okm, okm_len);
#endif /* CONFIG_SHA384 */
#ifdef CONFIG_SHA512
if (hash_len == 64)
return hmac_sha512_kdf(prk, prk_len, NULL,
(const u8 *) info, info_len,
okm, okm_len);
#endif /* CONFIG_SHA512 */
return -1;
}
static int sswu_curve_param(int group, int *z)
{
switch (group) {
case 19:
case 20:
case 21:
case 28:
*z = -2;
return 0;
case 25:
case 29:
*z = -5;
return 0;
case 26:
*z = -11;
return 0;
case 30:
*z = 2;
return 0;
}
return -1;
}
static void debug_print_bignum(const char *title, const struct crypto_bignum *a,
size_t prime_len)
{
u8 *bin;
bin = os_malloc(prime_len);
if (bin && crypto_bignum_to_bin(a, bin, prime_len, prime_len) >= 0)
wpa_hexdump_key(MSG_DEBUG, title, bin, prime_len);
else
wpa_printf(MSG_DEBUG, "Could not print bignum (%s)", title);
bin_clear_free(bin, prime_len);
}
static struct crypto_ec_point * sswu(struct crypto_ec *ec, int group,
const struct crypto_bignum *u)
{
int z_int;
const struct crypto_bignum *a, *b, *prime;
struct crypto_bignum *u2, *t1, *t2, *z, *t, *zero, *one, *two, *three,
*x1a, *x1b, *y = NULL;
struct crypto_bignum *x1 = NULL, *x2, *gx1, *gx2, *v = NULL;
unsigned int m_is_zero, is_qr, is_eq;
size_t prime_len;
u8 bin[SAE_MAX_ECC_PRIME_LEN];
u8 bin1[SAE_MAX_ECC_PRIME_LEN];
u8 bin2[SAE_MAX_ECC_PRIME_LEN];
u8 x_y[2 * SAE_MAX_ECC_PRIME_LEN];
struct crypto_ec_point *p = NULL;
if (sswu_curve_param(group, &z_int) < 0)
return NULL;
prime = crypto_ec_get_prime(ec);
prime_len = crypto_ec_prime_len(ec);
a = crypto_ec_get_a(ec);
b = crypto_ec_get_b(ec);
u2 = crypto_bignum_init();
t1 = crypto_bignum_init();
t2 = crypto_bignum_init();
z = crypto_bignum_init_uint(abs(z_int));
t = crypto_bignum_init();
zero = crypto_bignum_init_uint(0);
one = crypto_bignum_init_uint(1);
two = crypto_bignum_init_uint(2);
three = crypto_bignum_init_uint(3);
x1a = crypto_bignum_init();
x1b = crypto_bignum_init();
x2 = crypto_bignum_init();
gx1 = crypto_bignum_init();
gx2 = crypto_bignum_init();
if (!u2 || !t1 || !t2 || !z || !t || !zero || !one || !two || !three ||
!x1a || !x1b || !x2 || !gx1 || !gx2)
goto fail;
if (z_int < 0 && crypto_bignum_sub(prime, z, z) < 0)
goto fail;
/* m = z^2 * u^4 + z * u^2 */
/* --> tmp = z * u^2, m = tmp^2 + tmp */
/* u2 = u^2
* t1 = z * u2
* t2 = t1^2
* m = t1 = t1 + t2 */
if (crypto_bignum_sqrmod(u, prime, u2) < 0 ||
crypto_bignum_mulmod(z, u2, prime, t1) < 0 ||
crypto_bignum_sqrmod(t1, prime, t2) < 0 ||
crypto_bignum_addmod(t1, t2, prime, t1) < 0)
goto fail;
debug_print_bignum("SSWU: m", t1, prime_len);
/* l = CEQ(m, 0)
* t = CSEL(l, 0, inverse(m); where inverse(x) is calculated as
* x^(p-2) modulo p which will handle m == 0 case correctly */
/* TODO: Make sure crypto_bignum_is_zero() is constant time */
m_is_zero = const_time_eq(crypto_bignum_is_zero(t1), 1);
/* t = m^(p-2) modulo p */
if (crypto_bignum_sub(prime, two, t2) < 0 ||
crypto_bignum_exptmod(t1, t2, prime, t) < 0)
goto fail;
debug_print_bignum("SSWU: t", t, prime_len);
/* b / (z * a) */
if (crypto_bignum_mulmod(z, a, prime, t1) < 0 ||
crypto_bignum_inverse(t1, prime, t1) < 0 ||
crypto_bignum_mulmod(b, t1, prime, x1a) < 0)
goto fail;
debug_print_bignum("SSWU: x1a = b / (z * a)", x1a, prime_len);
/* (-b/a) * (1 + t) */
if (crypto_bignum_sub(prime, b, t1) < 0 ||
crypto_bignum_inverse(a, prime, t2) < 0 ||
crypto_bignum_mulmod(t1, t2, prime, t1) < 0 ||
crypto_bignum_addmod(one, t, prime, t2) < 0 ||
crypto_bignum_mulmod(t1, t2, prime, x1b) < 0)
goto fail;
debug_print_bignum("SSWU: x1b = (-b/a) * (1 + t)", x1b, prime_len);
/* x1 = CSEL(CEQ(m, 0), x1a, x1b) */
if (crypto_bignum_to_bin(x1a, bin1, sizeof(bin1), prime_len) < 0 ||
crypto_bignum_to_bin(x1b, bin2, sizeof(bin2), prime_len) < 0)
goto fail;
const_time_select_bin(m_is_zero, bin1, bin2, prime_len, bin);
x1 = crypto_bignum_init_set(bin, prime_len);
debug_print_bignum("SSWU: x1 = CSEL(l, x1a, x1b)", x1, prime_len);
/* gx1 = x1^3 + a * x1 + b */
if (crypto_bignum_exptmod(x1, three, prime, t1) < 0 ||
crypto_bignum_mulmod(a, x1, prime, t2) < 0 ||
crypto_bignum_addmod(t1, t2, prime, t1) < 0 ||
crypto_bignum_addmod(t1, b, prime, gx1) < 0)
goto fail;
debug_print_bignum("SSWU: gx1 = x1^3 + a * x1 + b", gx1, prime_len);
/* x2 = z * u^2 * x1 */
if (crypto_bignum_mulmod(z, u2, prime, t1) < 0 ||
crypto_bignum_mulmod(t1, x1, prime, x2) < 0)
goto fail;
debug_print_bignum("SSWU: x2 = z * u^2 * x1", x2, prime_len);
/* gx2 = x2^3 + a * x2 + b */
if (crypto_bignum_exptmod(x2, three, prime, t1) < 0 ||
crypto_bignum_mulmod(a, x2, prime, t2) < 0 ||
crypto_bignum_addmod(t1, t2, prime, t1) < 0 ||
crypto_bignum_addmod(t1, b, prime, gx2) < 0)
goto fail;
debug_print_bignum("SSWU: gx2 = x2^3 + a * x2 + b", gx2, prime_len);
/* l = gx1 is a quadratic residue modulo p
* --> gx1^((p-1)/2) modulo p is zero or one */
if (crypto_bignum_sub(prime, one, t1) < 0 ||
crypto_bignum_rshift(t1, 1, t1) < 0 ||
crypto_bignum_exptmod(gx1, t1, prime, t1) < 0)
goto fail;
debug_print_bignum("SSWU: gx1^((p-1)/2) modulo p", t1, prime_len);
is_qr = const_time_eq(crypto_bignum_is_zero(t1) |
crypto_bignum_is_one(t1), 1);
/* v = CSEL(l, gx1, gx2) */
if (crypto_bignum_to_bin(gx1, bin1, sizeof(bin1), prime_len) < 0 ||
crypto_bignum_to_bin(gx2, bin2, sizeof(bin2), prime_len) < 0)
goto fail;
const_time_select_bin(is_qr, bin1, bin2, prime_len, bin);
v = crypto_bignum_init_set(bin, prime_len);
debug_print_bignum("SSWU: v = CSEL(l, gx1, gx2)", v, prime_len);
/* x = CSEL(l, x1, x2) */
if (crypto_bignum_to_bin(x1, bin1, sizeof(bin1), prime_len) < 0 ||
crypto_bignum_to_bin(x2, bin2, sizeof(bin2), prime_len) < 0)
goto fail;
const_time_select_bin(is_qr, bin1, bin2, prime_len, x_y);
wpa_hexdump_key(MSG_DEBUG, "SSWU: x = CSEL(l, x1, x2)", x_y, prime_len);
/* y = sqrt(v) */
y = crypto_bignum_init();
/* TODO: Remove p = 3 mod 4 check and disable group 26 instead(?) */
if (crypto_bignum_to_bin(prime, bin1, sizeof(bin1), prime_len) < 0)
goto fail;
if ((bin1[prime_len - 1] & 0x03) == 3) {
/* For prime p such that p = 3 mod 4 --> v^((p+1)/4) */
if (!y ||
crypto_bignum_add(prime, one, t1) < 0 ||
crypto_bignum_rshift(t1, 2, t1) < 0 ||
crypto_bignum_exptmod(v, t1, prime, y) < 0)
goto fail;
} else {
wpa_printf(MSG_DEBUG, "SSWU: prime does not have p = 3 mod 4");
if (!y || crypto_bignum_sqrtmod(v, prime, y) < 0)
goto fail;
}
debug_print_bignum("SSWU: y = sqrt(v)", y, prime_len);
/* l = CEQ(LSB(u), LSB(y)) */
if (crypto_bignum_to_bin(u, bin1, sizeof(bin1), prime_len) < 0 ||
crypto_bignum_to_bin(y, bin2, sizeof(bin2), prime_len) < 0)
goto fail;
is_eq = const_time_eq(bin1[prime_len - 1] & 0x01,
bin2[prime_len - 1] & 0x01);
/* P = CSEL(l, (x,y), (x, p-y)) */
if (crypto_bignum_sub(prime, y, t1) < 0)
goto fail;
debug_print_bignum("SSWU: p - y", t1, prime_len);
if (crypto_bignum_to_bin(y, bin1, sizeof(bin1), prime_len) < 0 ||
crypto_bignum_to_bin(t1, bin2, sizeof(bin2), prime_len) < 0)
goto fail;
const_time_select_bin(is_eq, bin1, bin2, prime_len, &x_y[prime_len]);
/* output P */
wpa_hexdump_key(MSG_DEBUG, "SSWU: P.x", x_y, prime_len);
wpa_hexdump_key(MSG_DEBUG, "SSWU: P.y", &x_y[prime_len], prime_len);
p = crypto_ec_point_from_bin(ec, x_y);
fail:
crypto_bignum_deinit(u2, 1);
crypto_bignum_deinit(t1, 1);
crypto_bignum_deinit(t2, 1);
crypto_bignum_deinit(z, 0);
crypto_bignum_deinit(t, 1);
crypto_bignum_deinit(x1a, 1);
crypto_bignum_deinit(x1b, 1);
crypto_bignum_deinit(x1, 1);
crypto_bignum_deinit(x2, 1);
crypto_bignum_deinit(gx1, 1);
crypto_bignum_deinit(gx2, 1);
crypto_bignum_deinit(y, 1);
crypto_bignum_deinit(v, 1);
crypto_bignum_deinit(zero, 0);
crypto_bignum_deinit(one, 0);
crypto_bignum_deinit(two, 0);
crypto_bignum_deinit(three, 0);
forced_memzero(bin, sizeof(bin));
forced_memzero(bin1, sizeof(bin1));
forced_memzero(bin2, sizeof(bin2));
forced_memzero(x_y, sizeof(x_y));
return p;
}
static int sae_pwd_seed(size_t hash_len, const u8 *ssid, size_t ssid_len,
const u8 *password, size_t password_len,
const char *identifier, u8 *pwd_seed)
{
const u8 *addr[2];
size_t len[2];
size_t num_elem;
/* pwd-seed = HKDF-Extract(ssid, password [ || identifier ]) */
addr[0] = password;
len[0] = password_len;
num_elem = 1;
wpa_hexdump_ascii(MSG_DEBUG, "SAE: SSID", ssid, ssid_len);
wpa_hexdump_ascii_key(MSG_DEBUG, "SAE: password",
password, password_len);
if (identifier) {
wpa_printf(MSG_DEBUG, "SAE: password identifier: %s",
identifier);
addr[num_elem] = (const u8 *) identifier;
len[num_elem] = os_strlen(identifier);
num_elem++;
}
if (hkdf_extract(hash_len, ssid, ssid_len, num_elem, addr, len,
pwd_seed) < 0)
return -1;
wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-seed", pwd_seed, hash_len);
return 0;
}
size_t sae_ecc_prime_len_2_hash_len(size_t prime_len)
{
if (prime_len <= 256 / 8)
return 32;
if (prime_len <= 384 / 8)
return 48;
return 64;
}
struct crypto_ec_point *
sae_derive_pt_ecc(struct crypto_ec *ec, int group,
const u8 *ssid, size_t ssid_len,
const u8 *password, size_t password_len,
const char *identifier)
{
u8 pwd_seed[64];
u8 pwd_value[SAE_MAX_ECC_PRIME_LEN * 2];
size_t pwd_value_len, hash_len, prime_len;
const struct crypto_bignum *prime;
struct crypto_bignum *bn = NULL;
struct crypto_ec_point *p1 = NULL, *p2 = NULL, *pt = NULL;
prime = crypto_ec_get_prime(ec);
prime_len = crypto_ec_prime_len(ec);
if (prime_len > SAE_MAX_ECC_PRIME_LEN)
goto fail;
hash_len = sae_ecc_prime_len_2_hash_len(prime_len);
/* len = olen(p) + ceil(olen(p)/2) */
pwd_value_len = prime_len + (prime_len + 1) / 2;
if (sae_pwd_seed(hash_len, ssid, ssid_len, password, password_len,
identifier, pwd_seed) < 0)
goto fail;
/* pwd-value = HKDF-Expand(pwd-seed, "SAE Hash to Element u1 P1", len)
*/
if (hkdf_expand(hash_len, pwd_seed, hash_len,
"SAE Hash to Element u1 P1", pwd_value, pwd_value_len) <
0)
goto fail;
wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value (u1 P1)",
pwd_value, pwd_value_len);
/* u1 = pwd-value modulo p */
bn = crypto_bignum_init_set(pwd_value, pwd_value_len);
if (!bn || crypto_bignum_mod(bn, prime, bn) < 0 ||
crypto_bignum_to_bin(bn, pwd_value, sizeof(pwd_value),
prime_len) < 0)
goto fail;
wpa_hexdump_key(MSG_DEBUG, "SAE: u1", pwd_value, prime_len);
/* P1 = SSWU(u1) */
p1 = sswu(ec, group, bn);
if (!p1)
goto fail;
/* pwd-value = HKDF-Expand(pwd-seed, "SAE Hash to Element u2 P2", len)
*/
if (hkdf_expand(hash_len, pwd_seed, hash_len,
"SAE Hash to Element u2 P2", pwd_value,
pwd_value_len) < 0)
goto fail;
wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value (u2 P2)",
pwd_value, pwd_value_len);
/* u2 = pwd-value modulo p */
crypto_bignum_deinit(bn, 1);
bn = crypto_bignum_init_set(pwd_value, pwd_value_len);
if (!bn || crypto_bignum_mod(bn, prime, bn) < 0 ||
crypto_bignum_to_bin(bn, pwd_value, sizeof(pwd_value),
prime_len) < 0)
goto fail;
wpa_hexdump_key(MSG_DEBUG, "SAE: u2", pwd_value, prime_len);
/* P2 = SSWU(u2) */
p2 = sswu(ec, group, bn);
if (!p2)
goto fail;
/* PT = elem-op(P1, P2) */
pt = crypto_ec_point_init(ec);
if (!pt)
goto fail;
if (crypto_ec_point_add(ec, p1, p2, pt) < 0) {
crypto_ec_point_deinit(pt, 1);
pt = NULL;
}
fail:
forced_memzero(pwd_seed, sizeof(pwd_seed));
forced_memzero(pwd_value, sizeof(pwd_value));
crypto_bignum_deinit(bn, 1);
crypto_ec_point_deinit(p1, 1);
crypto_ec_point_deinit(p2, 1);
return pt;
}
size_t sae_ffc_prime_len_2_hash_len(size_t prime_len)
{
if (prime_len <= 2048 / 8)
return 32;
if (prime_len <= 3072 / 8)
return 48;
return 64;
}
static struct crypto_bignum *
sae_derive_pt_ffc(const struct dh_group *dh, int group,
const u8 *ssid, size_t ssid_len,
const u8 *password, size_t password_len,
const char *identifier)
{
size_t hash_len, prime_len, pwd_value_len;
struct crypto_bignum *prime, *order;
struct crypto_bignum *one = NULL, *two = NULL, *bn = NULL, *tmp = NULL,
*pt = NULL;
u8 pwd_seed[64];
u8 pwd_value[SAE_MAX_PRIME_LEN + SAE_MAX_PRIME_LEN / 2];
prime = crypto_bignum_init_set(dh->prime, dh->prime_len);
order = crypto_bignum_init_set(dh->order, dh->order_len);
if (!prime || !order)
goto fail;
prime_len = dh->prime_len;
if (prime_len > SAE_MAX_PRIME_LEN)
goto fail;
hash_len = sae_ffc_prime_len_2_hash_len(prime_len);
/* len = olen(p) + ceil(olen(p)/2) */
pwd_value_len = prime_len + (prime_len + 1) / 2;
if (pwd_value_len > sizeof(pwd_value))
goto fail;
if (sae_pwd_seed(hash_len, ssid, ssid_len, password, password_len,
identifier, pwd_seed) < 0)
goto fail;
/* pwd-value = HKDF-Expand(pwd-seed, "SAE Hash to Element", len) */
if (hkdf_expand(hash_len, pwd_seed, hash_len,
"SAE Hash to Element", pwd_value, pwd_value_len) < 0)
goto fail;
wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value",
pwd_value, pwd_value_len);
/* pwd-value = (pwd-value modulo (p-2)) + 2 */
bn = crypto_bignum_init_set(pwd_value, pwd_value_len);
one = crypto_bignum_init_uint(1);
two = crypto_bignum_init_uint(2);
tmp = crypto_bignum_init();
if (!bn || !one || !two || !tmp ||
crypto_bignum_sub(prime, two, tmp) < 0 ||
crypto_bignum_mod(bn, tmp, bn) < 0 ||
crypto_bignum_add(bn, two, bn) < 0 ||
crypto_bignum_to_bin(bn, pwd_value, sizeof(pwd_value),
prime_len) < 0)
goto fail;
wpa_hexdump_key(MSG_DEBUG, "SAE: pwd-value(reduced)",
pwd_value, prime_len);
/* PT = pwd-value^((p-1)/q) modulo p */
pt = crypto_bignum_init();
if (!pt ||
crypto_bignum_sub(prime, one, tmp) < 0 ||
crypto_bignum_div(tmp, order, tmp) < 0 ||
crypto_bignum_exptmod(bn, tmp, prime, pt) < 0) {
crypto_bignum_deinit(pt, 1);
pt = NULL;
goto fail;
}
debug_print_bignum("SAE: PT", pt, prime_len);
fail:
forced_memzero(pwd_seed, sizeof(pwd_seed));
forced_memzero(pwd_value, sizeof(pwd_value));
crypto_bignum_deinit(bn, 1);
crypto_bignum_deinit(tmp, 1);
crypto_bignum_deinit(one, 0);
crypto_bignum_deinit(two, 0);
crypto_bignum_deinit(prime, 0);
crypto_bignum_deinit(order, 0);
return pt;
}
static struct sae_pt *
sae_derive_pt_group(int group, const u8 *ssid, size_t ssid_len,
const u8 *password, size_t password_len,
const char *identifier)
{
struct sae_pt *pt;
wpa_printf(MSG_DEBUG, "SAE: Derive PT - group %d", group);
pt = os_zalloc(sizeof(*pt));
if (!pt)
return NULL;
pt->group = group;
pt->ec = crypto_ec_init(group);
if (pt->ec) {
pt->ecc_pt = sae_derive_pt_ecc(pt->ec, group, ssid, ssid_len,
password, password_len,
identifier);
if (!pt->ecc_pt) {
wpa_printf(MSG_DEBUG, "SAE: Failed to derive PT");
goto fail;
}
return pt;
}
pt->dh = dh_groups_get(group);
if (!pt->dh) {
wpa_printf(MSG_DEBUG, "SAE: Unsupported group %d", group);
goto fail;
}
pt->ffc_pt = sae_derive_pt_ffc(pt->dh, group, ssid, ssid_len,
password, password_len, identifier);
if (!pt->ffc_pt) {
wpa_printf(MSG_DEBUG, "SAE: Failed to derive PT");
goto fail;
}
return pt;
fail:
sae_deinit_pt(pt);
return NULL;
}
struct sae_pt * sae_derive_pt(int *groups, const u8 *ssid, size_t ssid_len,
const u8 *password, size_t password_len,
const char *identifier)
{
struct sae_pt *pt = NULL, *last = NULL, *tmp;
int default_groups[] = { 19, 0 };
int i;
if (!groups)
groups = default_groups;
for (i = 0; groups[i] > 0; i++) {
tmp = sae_derive_pt_group(groups[i], ssid, ssid_len, password,
password_len, identifier);
if (!tmp)
continue;
if (last)
last->next = tmp;
else
pt = tmp;
last = tmp;
}
return pt;
}
static void sae_max_min_addr(const u8 *addr[], size_t len[],
const u8 *addr1, const u8 *addr2)
{
len[0] = ETH_ALEN;
len[1] = ETH_ALEN;
if (os_memcmp(addr1, addr2, ETH_ALEN) > 0) {
addr[0] = addr1;
addr[1] = addr2;
} else {
addr[0] = addr2;
addr[1] = addr1;
}
}
struct crypto_ec_point *
sae_derive_pwe_from_pt_ecc(const struct sae_pt *pt,
const u8 *addr1, const u8 *addr2)
{
u8 bin[SAE_MAX_ECC_PRIME_LEN * 2];
size_t prime_len;
const u8 *addr[2];
size_t len[2];
u8 salt[64], hash[64];
size_t hash_len;
const struct crypto_bignum *order;
struct crypto_bignum *tmp = NULL, *val = NULL, *one = NULL;
struct crypto_ec_point *pwe = NULL;
wpa_printf(MSG_DEBUG, "SAE: Derive PWE from PT");
prime_len = crypto_ec_prime_len(pt->ec);
if (crypto_ec_point_to_bin(pt->ec, pt->ecc_pt,
bin, bin + prime_len) < 0)
return NULL;
wpa_hexdump_key(MSG_DEBUG, "SAE: PT.x", bin, prime_len);
wpa_hexdump_key(MSG_DEBUG, "SAE: PT.y", bin + prime_len, prime_len);
sae_max_min_addr(addr, len, addr1, addr2);
/* val = H(0^n,
* MAX(STA-A-MAC, STA-B-MAC) || MIN(STA-A-MAC, STA-B-MAC)) */
wpa_printf(MSG_DEBUG, "SAE: val = H(0^n, MAX(addrs) || MIN(addrs))");
hash_len = sae_ecc_prime_len_2_hash_len(prime_len);
os_memset(salt, 0, hash_len);
if (hkdf_extract(hash_len, salt, hash_len, 2, addr, len, hash) < 0)
goto fail;
wpa_hexdump(MSG_DEBUG, "SAE: val", hash, hash_len);
/* val = val modulo (q - 1) + 1 */
order = crypto_ec_get_order(pt->ec);
tmp = crypto_bignum_init();
val = crypto_bignum_init_set(hash, hash_len);
one = crypto_bignum_init_uint(1);
if (!tmp || !val || !one ||
crypto_bignum_sub(order, one, tmp) < 0 ||
crypto_bignum_mod(val, tmp, val) < 0 ||
crypto_bignum_add(val, one, val) < 0)
goto fail;
debug_print_bignum("SAE: val(reduced to 1..q-1)", val, prime_len);
/* PWE = scalar-op(val, PT) */
pwe = crypto_ec_point_init(pt->ec);
if (!pwe ||
crypto_ec_point_mul(pt->ec, pt->ecc_pt, val, pwe) < 0 ||
crypto_ec_point_to_bin(pt->ec, pwe, bin, bin + prime_len) < 0) {
crypto_ec_point_deinit(pwe, 1);
pwe = NULL;
goto fail;
}
wpa_hexdump_key(MSG_DEBUG, "SAE: PWE.x", bin, prime_len);
wpa_hexdump_key(MSG_DEBUG, "SAE: PWE.y", bin + prime_len, prime_len);
fail:
crypto_bignum_deinit(tmp, 1);
crypto_bignum_deinit(val, 1);
crypto_bignum_deinit(one, 0);
return pwe;
}
struct crypto_bignum *
sae_derive_pwe_from_pt_ffc(const struct sae_pt *pt,
const u8 *addr1, const u8 *addr2)
{
size_t prime_len;
const u8 *addr[2];
size_t len[2];
u8 salt[64], hash[64];
size_t hash_len;
struct crypto_bignum *tmp = NULL, *val = NULL, *one = NULL;
struct crypto_bignum *pwe = NULL, *order = NULL, *prime = NULL;
wpa_printf(MSG_DEBUG, "SAE: Derive PWE from PT");
prime = crypto_bignum_init_set(pt->dh->prime, pt->dh->prime_len);
order = crypto_bignum_init_set(pt->dh->order, pt->dh->order_len);
if (!prime || !order)
goto fail;
prime_len = pt->dh->prime_len;
sae_max_min_addr(addr, len, addr1, addr2);
/* val = H(0^n,
* MAX(STA-A-MAC, STA-B-MAC) || MIN(STA-A-MAC, STA-B-MAC)) */
wpa_printf(MSG_DEBUG, "SAE: val = H(0^n, MAX(addrs) || MIN(addrs))");
hash_len = sae_ffc_prime_len_2_hash_len(prime_len);
os_memset(salt, 0, hash_len);
if (hkdf_extract(hash_len, salt, hash_len, 2, addr, len, hash) < 0)
goto fail;
wpa_hexdump(MSG_DEBUG, "SAE: val", hash, hash_len);
/* val = val modulo (q - 1) + 1 */
tmp = crypto_bignum_init();
val = crypto_bignum_init_set(hash, hash_len);
one = crypto_bignum_init_uint(1);
if (!tmp || !val || !one ||
crypto_bignum_sub(order, one, tmp) < 0 ||
crypto_bignum_mod(val, tmp, val) < 0 ||
crypto_bignum_add(val, one, val) < 0)
goto fail;
debug_print_bignum("SAE: val(reduced to 1..q-1)", val, prime_len);
/* PWE = scalar-op(val, PT) */
pwe = crypto_bignum_init();
if (!pwe || crypto_bignum_exptmod(pt->ffc_pt, val, prime, pwe) < 0) {
crypto_bignum_deinit(pwe, 1);
pwe = NULL;
goto fail;
}
debug_print_bignum("SAE: PWE", pwe, prime_len);
fail:
crypto_bignum_deinit(tmp, 1);
crypto_bignum_deinit(val, 1);
crypto_bignum_deinit(one, 0);
crypto_bignum_deinit(prime, 0);
crypto_bignum_deinit(order, 0);
return pwe;
}
void sae_deinit_pt(struct sae_pt *pt)
{
struct sae_pt *prev;
while (pt) {
crypto_ec_point_deinit(pt->ecc_pt, 1);
crypto_bignum_deinit(pt->ffc_pt, 1);
crypto_ec_deinit(pt->ec);
prev = pt;
pt = pt->next;
os_free(prev);
}
}
static int sae_derive_commit_element_ecc(struct sae_data *sae,
struct crypto_bignum *mask)
{
@ -605,10 +1347,66 @@ int sae_prepare_commit(const u8 *addr1, const u8 *addr2,
identifier) < 0) ||
(sae->tmp->dh && sae_derive_pwe_ffc(sae, addr1, addr2, password,
password_len,
identifier) < 0) ||
sae_derive_commit(sae) < 0)
identifier) < 0))
return -1;
return 0;
sae->tmp->h2e = 0;
return sae_derive_commit(sae);
}
int sae_prepare_commit_pt(struct sae_data *sae, const struct sae_pt *pt,
const u8 *addr1, const u8 *addr2,
int *rejected_groups)
{
if (!sae->tmp)
return -1;
while (pt) {
if (pt->group == sae->group)
break;
pt = pt->next;
}
if (!pt) {
wpa_printf(MSG_INFO, "SAE: Could not find PT for group %u",
sae->group);
return -1;
}
sae->tmp->own_addr_higher = os_memcmp(addr1, addr2, ETH_ALEN) > 0;
wpabuf_free(sae->tmp->own_rejected_groups);
sae->tmp->own_rejected_groups = NULL;
if (rejected_groups) {
int count, i;
struct wpabuf *groups;
count = int_array_len(rejected_groups);
groups = wpabuf_alloc(count * 2);
if (!groups)
return -1;
for (i = 0; i < count; i++)
wpabuf_put_le16(groups, rejected_groups[i]);
sae->tmp->own_rejected_groups = groups;
}
if (pt->ec) {
crypto_ec_point_deinit(sae->tmp->pwe_ecc, 1);
sae->tmp->pwe_ecc = sae_derive_pwe_from_pt_ecc(pt, addr1,
addr2);
if (!sae->tmp->pwe_ecc)
return -1;
}
if (pt->dh) {
crypto_bignum_deinit(sae->tmp->pwe_ffc, 1);
sae->tmp->pwe_ffc = sae_derive_pwe_from_pt_ffc(pt, addr1,
addr2);
if (!sae->tmp->pwe_ffc)
return -1;
}
sae->tmp->h2e = 1;
return sae_derive_commit(sae);
}

26
src/common/sae.h
View file

@ -43,7 +43,20 @@ struct sae_temporary_data {
char *pw_id;
int vlan_id;
u8 bssid[ETH_ALEN];
struct wpabuf *own_rejected_groups;
struct wpabuf *peer_rejected_groups;
unsigned int h2e:1;
unsigned int own_addr_higher:1;
};
struct sae_pt {
struct sae_pt *next;
int group;
struct crypto_ec *ec;
struct crypto_ec_point *ecc_pt;
const struct dh_group *dh;
struct crypto_bignum *ffc_pt;
};
enum sae_state {
@ -69,6 +82,9 @@ void sae_clear_data(struct sae_data *sae);
int sae_prepare_commit(const u8 *addr1, const u8 *addr2,
const u8 *password, size_t password_len,
const char *identifier, struct sae_data *sae);
int sae_prepare_commit_pt(struct sae_data *sae, const struct sae_pt *pt,
const u8 *addr1, const u8 *addr2,
int *rejected_groups);
int sae_process_commit(struct sae_data *sae);
void sae_write_commit(struct sae_data *sae, struct wpabuf *buf,
const struct wpabuf *token, const char *identifier);
@ -79,5 +95,15 @@ void sae_write_confirm(struct sae_data *sae, struct wpabuf *buf);
int sae_check_confirm(struct sae_data *sae, const u8 *data, size_t len);
u16 sae_group_allowed(struct sae_data *sae, int *allowed_groups, u16 group);
const char * sae_state_txt(enum sae_state state);
struct sae_pt * sae_derive_pt(int *groups, const u8 *ssid, size_t ssid_len,
const u8 *password, size_t password_len,
const char *identifier);
struct crypto_ec_point *
sae_derive_pwe_from_pt_ecc(const struct sae_pt *pt,
const u8 *addr1, const u8 *addr2);
struct crypto_bignum *
sae_derive_pwe_from_pt_ffc(const struct sae_pt *pt,
const u8 *addr1, const u8 *addr2);
void sae_deinit_pt(struct sae_pt *pt);
#endif /* SAE_H */