2 * Wi-Fi Protected Setup - common functionality
3 * Copyright (c) 2008, Jouni Malinen <j@w1.fi>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
9 * Alternatively, this software may be distributed under the terms of BSD
12 * See README and COPYING for more details.
18 #include "dh_groups.h"
23 #include "wps_dev_attr.h"
26 void wps_kdf(const u8 *key, const u8 *label_prefix, size_t label_prefix_len,
27 const char *label, u8 *res, size_t res_len)
29 u8 i_buf[4], key_bits[4];
33 u8 hash[SHA256_MAC_LEN], *opos;
36 WPA_PUT_BE32(key_bits, res_len * 8);
39 len[0] = sizeof(i_buf);
40 addr[1] = label_prefix;
41 len[1] = label_prefix_len;
42 addr[2] = (const u8 *) label;
43 len[2] = os_strlen(label);
45 len[3] = sizeof(key_bits);
47 iter = (res_len + SHA256_MAC_LEN - 1) / SHA256_MAC_LEN;
51 for (i = 1; i <= iter; i++) {
52 WPA_PUT_BE32(i_buf, i);
53 hmac_sha256_vector(key, SHA256_MAC_LEN, 4, addr, len, hash);
55 os_memcpy(opos, hash, SHA256_MAC_LEN);
56 opos += SHA256_MAC_LEN;
57 left -= SHA256_MAC_LEN;
59 os_memcpy(opos, hash, left);
64 int wps_derive_keys(struct wps_data *wps)
66 struct wpabuf *pubkey, *dh_shared;
67 u8 dhkey[SHA256_MAC_LEN], kdk[SHA256_MAC_LEN];
70 u8 keys[WPS_AUTHKEY_LEN + WPS_KEYWRAPKEY_LEN + WPS_EMSK_LEN];
72 if (wps->dh_privkey == NULL) {
73 wpa_printf(MSG_DEBUG, "WPS: Own DH private key not available");
77 pubkey = wps->registrar ? wps->dh_pubkey_e : wps->dh_pubkey_r;
79 wpa_printf(MSG_DEBUG, "WPS: Peer DH public key not available");
83 dh_shared = dh_derive_shared(pubkey, wps->dh_privkey,
84 dh_groups_get(WPS_DH_GROUP));
85 dh_shared = wpabuf_zeropad(dh_shared, 192);
86 if (dh_shared == NULL) {
87 wpa_printf(MSG_DEBUG, "WPS: Failed to derive DH shared key");
91 /* Own DH private key is not needed anymore */
92 wpabuf_free(wps->dh_privkey);
93 wps->dh_privkey = NULL;
95 wpa_hexdump_buf_key(MSG_DEBUG, "WPS: DH shared key", dh_shared);
97 /* DHKey = SHA-256(g^AB mod p) */
98 addr[0] = wpabuf_head(dh_shared);
99 len[0] = wpabuf_len(dh_shared);
100 sha256_vector(1, addr, len, dhkey);
101 wpa_hexdump_key(MSG_DEBUG, "WPS: DHKey", dhkey, sizeof(dhkey));
102 wpabuf_free(dh_shared);
104 /* KDK = HMAC-SHA-256_DHKey(N1 || EnrolleeMAC || N2) */
105 addr[0] = wps->nonce_e;
106 len[0] = WPS_NONCE_LEN;
107 addr[1] = wps->mac_addr_e;
109 addr[2] = wps->nonce_r;
110 len[2] = WPS_NONCE_LEN;
111 hmac_sha256_vector(dhkey, sizeof(dhkey), 3, addr, len, kdk);
112 wpa_hexdump_key(MSG_DEBUG, "WPS: KDK", kdk, sizeof(kdk));
114 wps_kdf(kdk, NULL, 0, "Wi-Fi Easy and Secure Key Derivation",
116 os_memcpy(wps->authkey, keys, WPS_AUTHKEY_LEN);
117 os_memcpy(wps->keywrapkey, keys + WPS_AUTHKEY_LEN, WPS_KEYWRAPKEY_LEN);
118 os_memcpy(wps->emsk, keys + WPS_AUTHKEY_LEN + WPS_KEYWRAPKEY_LEN,
121 wpa_hexdump_key(MSG_DEBUG, "WPS: AuthKey",
122 wps->authkey, WPS_AUTHKEY_LEN);
123 wpa_hexdump_key(MSG_DEBUG, "WPS: KeyWrapKey",
124 wps->keywrapkey, WPS_KEYWRAPKEY_LEN);
125 wpa_hexdump_key(MSG_DEBUG, "WPS: EMSK", wps->emsk, WPS_EMSK_LEN);
131 int wps_derive_mgmt_keys(struct wps_data *wps)
133 u8 nonces[2 * WPS_NONCE_LEN];
134 u8 keys[WPS_MGMTAUTHKEY_LEN + WPS_MGMTENCKEY_LEN];
135 u8 hash[SHA256_MAC_LEN];
138 const char *auth_label = "WFA-WLAN-Management-MgmtAuthKey";
139 const char *enc_label = "WFA-WLAN-Management-MgmtEncKey";
141 /* MgmtAuthKey || MgmtEncKey =
142 * kdf(EMSK, N1 || N2 || "WFA-WLAN-Management-Keys", 384) */
143 os_memcpy(nonces, wps->nonce_e, WPS_NONCE_LEN);
144 os_memcpy(nonces + WPS_NONCE_LEN, wps->nonce_r, WPS_NONCE_LEN);
145 wps_kdf(wps->emsk, nonces, sizeof(nonces), "WFA-WLAN-Management-Keys",
147 os_memcpy(wps->mgmt_auth_key, keys, WPS_MGMTAUTHKEY_LEN);
148 os_memcpy(wps->mgmt_enc_key, keys + WPS_MGMTAUTHKEY_LEN,
152 len[0] = sizeof(nonces);
154 /* MgmtEncKeyID = first 128 bits of
155 * SHA-256(N1 || N2 || "WFA-WLAN-Management-MgmtAuthKey") */
156 addr[1] = (const u8 *) auth_label;
157 len[1] = os_strlen(auth_label);
158 sha256_vector(2, addr, len, hash);
159 os_memcpy(wps->mgmt_auth_key_id, hash, WPS_MGMT_KEY_ID_LEN);
161 /* MgmtEncKeyID = first 128 bits of
162 * SHA-256(N1 || N2 || "WFA-WLAN-Management-MgmtEncKey") */
163 addr[1] = (const u8 *) enc_label;
164 len[1] = os_strlen(enc_label);
165 sha256_vector(2, addr, len, hash);
166 os_memcpy(wps->mgmt_enc_key_id, hash, WPS_MGMT_KEY_ID_LEN);
168 wpa_hexdump_key(MSG_DEBUG, "WPS: MgmtAuthKey",
169 wps->mgmt_auth_key, WPS_MGMTAUTHKEY_LEN);
170 wpa_hexdump(MSG_DEBUG, "WPS: MgmtAuthKeyID",
171 wps->mgmt_auth_key_id, WPS_MGMT_KEY_ID_LEN);
172 wpa_hexdump_key(MSG_DEBUG, "WPS: MgmtEncKey",
173 wps->mgmt_enc_key, WPS_MGMTENCKEY_LEN);
174 wpa_hexdump(MSG_DEBUG, "WPS: MgmtEncKeyID",
175 wps->mgmt_enc_key_id, WPS_MGMT_KEY_ID_LEN);
181 void wps_derive_psk(struct wps_data *wps, const u8 *dev_passwd,
182 size_t dev_passwd_len)
184 u8 hash[SHA256_MAC_LEN];
186 hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN, dev_passwd,
187 (dev_passwd_len + 1) / 2, hash);
188 os_memcpy(wps->psk1, hash, WPS_PSK_LEN);
189 hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN,
190 dev_passwd + (dev_passwd_len + 1) / 2,
191 dev_passwd_len / 2, hash);
192 os_memcpy(wps->psk2, hash, WPS_PSK_LEN);
194 wpa_hexdump_ascii_key(MSG_DEBUG, "WPS: Device Password",
195 dev_passwd, dev_passwd_len);
196 wpa_hexdump_key(MSG_DEBUG, "WPS: PSK1", wps->psk1, WPS_PSK_LEN);
197 wpa_hexdump_key(MSG_DEBUG, "WPS: PSK2", wps->psk2, WPS_PSK_LEN);
201 struct wpabuf * wps_decrypt_encr_settings(struct wps_data *wps, const u8 *encr,
204 struct wpabuf *decrypted;
205 const size_t block_size = 16;
211 if (encr == NULL || encr_len < 2 * block_size || encr_len % block_size)
213 wpa_printf(MSG_DEBUG, "WPS: No Encrypted Settings received");
217 decrypted = wpabuf_alloc(encr_len - block_size);
218 if (decrypted == NULL)
221 wpa_hexdump(MSG_MSGDUMP, "WPS: Encrypted Settings", encr, encr_len);
222 wpabuf_put_data(decrypted, encr + block_size, encr_len - block_size);
223 if (aes_128_cbc_decrypt(wps->keywrapkey, encr, wpabuf_mhead(decrypted),
224 wpabuf_len(decrypted))) {
225 wpabuf_free(decrypted);
229 wpa_hexdump_buf_key(MSG_MSGDUMP, "WPS: Decrypted Encrypted Settings",
232 pos = wpabuf_head_u8(decrypted) + wpabuf_len(decrypted) - 1;
234 if (pad > wpabuf_len(decrypted)) {
235 wpa_printf(MSG_DEBUG, "WPS: Invalid PKCS#5 v2.0 pad value");
236 wpabuf_free(decrypted);
239 for (i = 0; i < pad; i++) {
241 wpa_printf(MSG_DEBUG, "WPS: Invalid PKCS#5 v2.0 pad "
243 wpabuf_free(decrypted);
247 decrypted->used -= pad;
254 * wps_pin_checksum - Compute PIN checksum
255 * @pin: Seven digit PIN (i.e., eight digit PIN without the checksum digit)
256 * Returns: Checksum digit
258 unsigned int wps_pin_checksum(unsigned int pin)
260 unsigned int accum = 0;
262 accum += 3 * (pin % 10);
268 return (10 - accum % 10) % 10;
273 * wps_pin_valid - Check whether a PIN has a valid checksum
274 * @pin: Eight digit PIN (i.e., including the checksum digit)
275 * Returns: 1 if checksum digit is valid, or 0 if not
277 unsigned int wps_pin_valid(unsigned int pin)
279 return wps_pin_checksum(pin / 10) == (pin % 10);
284 * wps_generate_pin - Generate a random PIN
285 * Returns: Eight digit PIN (i.e., including the checksum digit)
287 unsigned int wps_generate_pin(void)
291 /* Generate seven random digits for the PIN */
292 if (os_get_random((unsigned char *) &val, sizeof(val)) < 0) {
295 val = os_random() ^ now.sec ^ now.usec;
299 /* Append checksum digit */
300 return val * 10 + wps_pin_checksum(val);
304 void wps_fail_event(struct wps_context *wps, enum wps_msg_type msg)
306 union wps_event_data data;
308 if (wps->event_cb == NULL)
311 os_memset(&data, 0, sizeof(data));
313 wps->event_cb(wps->cb_ctx, WPS_EV_FAIL, &data);
317 void wps_success_event(struct wps_context *wps)
319 if (wps->event_cb == NULL)
322 wps->event_cb(wps->cb_ctx, WPS_EV_SUCCESS, NULL);
326 void wps_pwd_auth_fail_event(struct wps_context *wps, int enrollee, int part)
328 union wps_event_data data;
330 if (wps->event_cb == NULL)
333 os_memset(&data, 0, sizeof(data));
334 data.pwd_auth_fail.enrollee = enrollee;
335 data.pwd_auth_fail.part = part;
336 wps->event_cb(wps->cb_ctx, WPS_EV_PWD_AUTH_FAIL, &data);