hostap/src/wps/wps_common.c

314 lines
8.3 KiB
C
Raw Normal View History

/*
* Wi-Fi Protected Setup - common functionality
* Copyright (c) 2008, Jouni Malinen <j@w1.fi>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Alternatively, this software may be distributed under the terms of BSD
* license.
*
* See README and COPYING for more details.
*/
#include "includes.h"
#include "common.h"
#include "dh_groups.h"
#include "sha256.h"
#include "aes_wrap.h"
#include "crypto.h"
#include "wps_i.h"
#include "wps_dev_attr.h"
void wps_kdf(const u8 *key, const u8 *label_prefix, size_t label_prefix_len,
const char *label, u8 *res, size_t res_len)
{
u8 i_buf[4], key_bits[4];
const u8 *addr[4];
size_t len[4];
int i, iter;
u8 hash[SHA256_MAC_LEN], *opos;
size_t left;
WPA_PUT_BE32(key_bits, res_len * 8);
addr[0] = i_buf;
len[0] = sizeof(i_buf);
addr[1] = label_prefix;
len[1] = label_prefix_len;
addr[2] = (const u8 *) label;
len[2] = os_strlen(label);
addr[3] = key_bits;
len[3] = sizeof(key_bits);
iter = (res_len + SHA256_MAC_LEN - 1) / SHA256_MAC_LEN;
opos = res;
left = res_len;
for (i = 1; i <= iter; i++) {
WPA_PUT_BE32(i_buf, i);
hmac_sha256_vector(key, SHA256_MAC_LEN, 4, addr, len, hash);
if (i < iter) {
os_memcpy(opos, hash, SHA256_MAC_LEN);
opos += SHA256_MAC_LEN;
left -= SHA256_MAC_LEN;
} else
os_memcpy(opos, hash, left);
}
}
int wps_derive_keys(struct wps_data *wps)
{
struct wpabuf *pubkey, *dh_shared;
u8 dhkey[SHA256_MAC_LEN], kdk[SHA256_MAC_LEN];
const u8 *addr[3];
size_t len[3];
u8 keys[WPS_AUTHKEY_LEN + WPS_KEYWRAPKEY_LEN + WPS_EMSK_LEN];
if (wps->dh_privkey == NULL) {
wpa_printf(MSG_DEBUG, "WPS: Own DH private key not available");
return -1;
}
pubkey = wps->registrar ? wps->dh_pubkey_e : wps->dh_pubkey_r;
if (pubkey == NULL) {
wpa_printf(MSG_DEBUG, "WPS: Peer DH public key not available");
return -1;
}
dh_shared = dh_derive_shared(pubkey, wps->dh_privkey,
dh_groups_get(WPS_DH_GROUP));
if (dh_shared == NULL) {
wpa_printf(MSG_DEBUG, "WPS: Failed to derive DH shared key");
return -1;
}
/* Own DH private key is not needed anymore */
wpabuf_free(wps->dh_privkey);
wps->dh_privkey = NULL;
wpa_hexdump_buf_key(MSG_DEBUG, "WPS: DH shared key", dh_shared);
/* DHKey = SHA-256(g^AB mod p) */
addr[0] = wpabuf_head(dh_shared);
len[0] = wpabuf_len(dh_shared);
sha256_vector(1, addr, len, dhkey);
wpa_hexdump_key(MSG_DEBUG, "WPS: DHKey", dhkey, sizeof(dhkey));
wpabuf_free(dh_shared);
/* KDK = HMAC-SHA-256_DHKey(N1 || EnrolleeMAC || N2) */
addr[0] = wps->nonce_e;
len[0] = WPS_NONCE_LEN;
addr[1] = wps->mac_addr_e;
len[1] = ETH_ALEN;
addr[2] = wps->nonce_r;
len[2] = WPS_NONCE_LEN;
hmac_sha256_vector(dhkey, sizeof(dhkey), 3, addr, len, kdk);
wpa_hexdump_key(MSG_DEBUG, "WPS: KDK", kdk, sizeof(kdk));
wps_kdf(kdk, NULL, 0, "Wi-Fi Easy and Secure Key Derivation",
keys, sizeof(keys));
os_memcpy(wps->authkey, keys, WPS_AUTHKEY_LEN);
os_memcpy(wps->keywrapkey, keys + WPS_AUTHKEY_LEN, WPS_KEYWRAPKEY_LEN);
os_memcpy(wps->emsk, keys + WPS_AUTHKEY_LEN + WPS_KEYWRAPKEY_LEN,
WPS_EMSK_LEN);
wpa_hexdump_key(MSG_DEBUG, "WPS: AuthKey",
wps->authkey, WPS_AUTHKEY_LEN);
wpa_hexdump_key(MSG_DEBUG, "WPS: KeyWrapKey",
wps->keywrapkey, WPS_KEYWRAPKEY_LEN);
wpa_hexdump_key(MSG_DEBUG, "WPS: EMSK", wps->emsk, WPS_EMSK_LEN);
return 0;
}
int wps_derive_mgmt_keys(struct wps_data *wps)
{
u8 nonces[2 * WPS_NONCE_LEN];
u8 keys[WPS_MGMTAUTHKEY_LEN + WPS_MGMTENCKEY_LEN];
u8 hash[SHA256_MAC_LEN];
const u8 *addr[2];
size_t len[2];
const char *auth_label = "WFA-WLAN-Management-MgmtAuthKey";
const char *enc_label = "WFA-WLAN-Management-MgmtEncKey";
/* MgmtAuthKey || MgmtEncKey =
* kdf(EMSK, N1 || N2 || "WFA-WLAN-Management-Keys", 384) */
os_memcpy(nonces, wps->nonce_e, WPS_NONCE_LEN);
os_memcpy(nonces + WPS_NONCE_LEN, wps->nonce_r, WPS_NONCE_LEN);
wps_kdf(wps->emsk, nonces, sizeof(nonces), "WFA-WLAN-Management-Keys",
keys, sizeof(keys));
os_memcpy(wps->mgmt_auth_key, keys, WPS_MGMTAUTHKEY_LEN);
os_memcpy(wps->mgmt_enc_key, keys + WPS_MGMTAUTHKEY_LEN,
WPS_MGMTENCKEY_LEN);
addr[0] = nonces;
len[0] = sizeof(nonces);
/* MgmtEncKeyID = first 128 bits of
* SHA-256(N1 || N2 || "WFA-WLAN-Management-MgmtAuthKey") */
addr[1] = (const u8 *) auth_label;
len[1] = os_strlen(auth_label);
sha256_vector(2, addr, len, hash);
os_memcpy(wps->mgmt_auth_key_id, hash, WPS_MGMT_KEY_ID_LEN);
/* MgmtEncKeyID = first 128 bits of
* SHA-256(N1 || N2 || "WFA-WLAN-Management-MgmtEncKey") */
addr[1] = (const u8 *) enc_label;
len[1] = os_strlen(enc_label);
sha256_vector(2, addr, len, hash);
os_memcpy(wps->mgmt_enc_key_id, hash, WPS_MGMT_KEY_ID_LEN);
wpa_hexdump_key(MSG_DEBUG, "WPS: MgmtAuthKey",
wps->mgmt_auth_key, WPS_MGMTAUTHKEY_LEN);
wpa_hexdump(MSG_DEBUG, "WPS: MgmtAuthKeyID",
wps->mgmt_auth_key_id, WPS_MGMT_KEY_ID_LEN);
wpa_hexdump_key(MSG_DEBUG, "WPS: MgmtEncKey",
wps->mgmt_enc_key, WPS_MGMTENCKEY_LEN);
wpa_hexdump(MSG_DEBUG, "WPS: MgmtEncKeyID",
wps->mgmt_enc_key_id, WPS_MGMT_KEY_ID_LEN);
return 0;
}
void wps_derive_psk(struct wps_data *wps, const u8 *dev_passwd,
size_t dev_passwd_len)
{
u8 hash[SHA256_MAC_LEN];
hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN, dev_passwd,
(dev_passwd_len + 1) / 2, hash);
os_memcpy(wps->psk1, hash, WPS_PSK_LEN);
hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN,
dev_passwd + (dev_passwd_len + 1) / 2,
dev_passwd_len / 2, hash);
os_memcpy(wps->psk2, hash, WPS_PSK_LEN);
wpa_hexdump_ascii_key(MSG_DEBUG, "WPS: Device Password",
dev_passwd, dev_passwd_len);
wpa_hexdump_key(MSG_DEBUG, "WPS: PSK1", wps->psk1, WPS_PSK_LEN);
wpa_hexdump_key(MSG_DEBUG, "WPS: PSK2", wps->psk2, WPS_PSK_LEN);
}
struct wpabuf * wps_decrypt_encr_settings(struct wps_data *wps, const u8 *encr,
size_t encr_len)
{
struct wpabuf *decrypted;
const size_t block_size = 16;
size_t i;
u8 pad;
const u8 *pos;
/* AES-128-CBC */
if (encr == NULL || encr_len < 2 * block_size || encr_len % block_size)
{
wpa_printf(MSG_DEBUG, "WPS: No Encrypted Settings received");
return NULL;
}
decrypted = wpabuf_alloc(encr_len - block_size);
if (decrypted == NULL)
return NULL;
wpa_hexdump(MSG_MSGDUMP, "WPS: Encrypted Settings", encr, encr_len);
wpabuf_put_data(decrypted, encr + block_size, encr_len - block_size);
if (aes_128_cbc_decrypt(wps->keywrapkey, encr, wpabuf_mhead(decrypted),
wpabuf_len(decrypted))) {
wpabuf_free(decrypted);
return NULL;
}
wpa_hexdump_buf_key(MSG_MSGDUMP, "WPS: Decrypted Encrypted Settings",
decrypted);
pos = wpabuf_head_u8(decrypted) + wpabuf_len(decrypted) - 1;
pad = *pos;
if (pad > wpabuf_len(decrypted)) {
wpa_printf(MSG_DEBUG, "WPS: Invalid PKCS#5 v2.0 pad value");
wpabuf_free(decrypted);
return NULL;
}
for (i = 0; i < pad; i++) {
if (*pos-- != pad) {
wpa_printf(MSG_DEBUG, "WPS: Invalid PKCS#5 v2.0 pad "
"string");
wpabuf_free(decrypted);
return NULL;
}
}
decrypted->used -= pad;
return decrypted;
}
/**
* wps_pin_checksum - Compute PIN checksum
* @pin: Seven digit PIN (i.e., eight digit PIN without the checksum digit)
* Returns: Checksum digit
*/
unsigned int wps_pin_checksum(unsigned int pin)
{
unsigned int accum = 0;
while (pin) {
accum += 3 * (pin % 10);
pin /= 10;
accum += pin % 10;
pin /= 10;
}
return (10 - accum % 10) % 10;
}
/**
* wps_pin_valid - Check whether a PIN has a valid checksum
* @pin: Eight digit PIN (i.e., including the checksum digit)
* Returns: 1 if checksum digit is valid, or 0 if not
*/
unsigned int wps_pin_valid(unsigned int pin)
{
return wps_pin_checksum(pin / 10) == (pin % 10);
}
/**
* wps_generate_pin - Generate a random PIN
* Returns: Eight digit PIN (i.e., including the checksum digit)
*/
unsigned int wps_generate_pin(void)
{
unsigned int val;
/* Generate seven random digits for the PIN */
if (os_get_random((unsigned char *) &val, sizeof(val)) < 0) {
struct os_time now;
os_get_time(&now);
val = os_random() ^ now.sec ^ now.usec;
}
val %= 10000000;
/* Append checksum digit */
return val * 10 + wps_pin_checksum(val);
}
void wps_fail_event(struct wps_context *wps, enum wps_msg_type msg)
{
union wps_event_data data;
if (wps->event_cb == NULL)
return;
os_memset(&data, 0, sizeof(data));
data.fail.msg = msg;
wps->event_cb(wps->cb_ctx, WPS_EV_FAIL, &data);
}