1 /*
2 * Wi-Fi Protected Setup - common functionality
3 * Copyright (c) 2008, Jouni Malinen <j@w1.fi>
4 *
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.
8 *
9 * Alternatively, this software may be distributed under the terms of BSD
10 * license.
11 *
12 * See README and COPYING for more details.
13 */
14
15 #include "includes.h"
16
17 #include "common.h"
18 #include "crypto/dh_groups.h"
19 #include "crypto/sha256.h"
20 #include "crypto/aes_wrap.h"
21 #include "crypto/crypto.h"
22 #include "wps_i.h"
23 #include "wps_dev_attr.h"
24
25
wps_kdf(const u8 * key,const u8 * label_prefix,size_t label_prefix_len,const char * label,u8 * res,size_t res_len)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)
28 {
29 u8 i_buf[4], key_bits[4];
30 const u8 *addr[4];
31 size_t len[4];
32 int i, iter;
33 u8 hash[SHA256_MAC_LEN], *opos;
34 size_t left;
35
36 WPA_PUT_BE32(key_bits, res_len * 8);
37
38 addr[0] = i_buf;
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);
44 addr[3] = key_bits;
45 len[3] = sizeof(key_bits);
46
47 iter = (res_len + SHA256_MAC_LEN - 1) / SHA256_MAC_LEN;
48 opos = res;
49 left = res_len;
50
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);
54 if (i < iter) {
55 os_memcpy(opos, hash, SHA256_MAC_LEN);
56 opos += SHA256_MAC_LEN;
57 left -= SHA256_MAC_LEN;
58 } else
59 os_memcpy(opos, hash, left);
60 }
61 }
62
63
wps_derive_keys(struct wps_data * wps)64 int wps_derive_keys(struct wps_data *wps)
65 {
66 struct wpabuf *pubkey, *dh_shared;
67 u8 dhkey[SHA256_MAC_LEN], kdk[SHA256_MAC_LEN];
68 const u8 *addr[3];
69 size_t len[3];
70 u8 keys[WPS_AUTHKEY_LEN + WPS_KEYWRAPKEY_LEN + WPS_EMSK_LEN];
71
72 if (wps->dh_privkey == NULL) {
73 wpa_printf(MSG_DEBUG, "WPS: Own DH private key not available");
74 return -1;
75 }
76
77 pubkey = wps->registrar ? wps->dh_pubkey_e : wps->dh_pubkey_r;
78 if (pubkey == NULL) {
79 wpa_printf(MSG_DEBUG, "WPS: Peer DH public key not available");
80 return -1;
81 }
82
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");
88 return -1;
89 }
90
91 /* Own DH private key is not needed anymore */
92 wpabuf_free(wps->dh_privkey);
93 wps->dh_privkey = NULL;
94
95 wpa_hexdump_buf_key(MSG_DEBUG, "WPS: DH shared key", dh_shared);
96
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);
103
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;
108 len[1] = ETH_ALEN;
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));
113
114 wps_kdf(kdk, NULL, 0, "Wi-Fi Easy and Secure Key Derivation",
115 keys, sizeof(keys));
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,
119 WPS_EMSK_LEN);
120
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);
126
127 return 0;
128 }
129
130
wps_derive_psk(struct wps_data * wps,const u8 * dev_passwd,size_t dev_passwd_len)131 void wps_derive_psk(struct wps_data *wps, const u8 *dev_passwd,
132 size_t dev_passwd_len)
133 {
134 u8 hash[SHA256_MAC_LEN];
135
136 hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN, dev_passwd,
137 (dev_passwd_len + 1) / 2, hash);
138 os_memcpy(wps->psk1, hash, WPS_PSK_LEN);
139 hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN,
140 dev_passwd + (dev_passwd_len + 1) / 2,
141 dev_passwd_len / 2, hash);
142 os_memcpy(wps->psk2, hash, WPS_PSK_LEN);
143
144 wpa_hexdump_ascii_key(MSG_DEBUG, "WPS: Device Password",
145 dev_passwd, dev_passwd_len);
146 wpa_hexdump_key(MSG_DEBUG, "WPS: PSK1", wps->psk1, WPS_PSK_LEN);
147 wpa_hexdump_key(MSG_DEBUG, "WPS: PSK2", wps->psk2, WPS_PSK_LEN);
148 }
149
150
wps_decrypt_encr_settings(struct wps_data * wps,const u8 * encr,size_t encr_len)151 struct wpabuf * wps_decrypt_encr_settings(struct wps_data *wps, const u8 *encr,
152 size_t encr_len)
153 {
154 struct wpabuf *decrypted;
155 const size_t block_size = 16;
156 size_t i;
157 u8 pad;
158 const u8 *pos;
159
160 /* AES-128-CBC */
161 if (encr == NULL || encr_len < 2 * block_size || encr_len % block_size)
162 {
163 wpa_printf(MSG_DEBUG, "WPS: No Encrypted Settings received");
164 return NULL;
165 }
166
167 decrypted = wpabuf_alloc(encr_len - block_size);
168 if (decrypted == NULL)
169 return NULL;
170
171 wpa_hexdump(MSG_MSGDUMP, "WPS: Encrypted Settings", encr, encr_len);
172 wpabuf_put_data(decrypted, encr + block_size, encr_len - block_size);
173 if (aes_128_cbc_decrypt(wps->keywrapkey, encr, wpabuf_mhead(decrypted),
174 wpabuf_len(decrypted))) {
175 wpabuf_free(decrypted);
176 return NULL;
177 }
178
179 wpa_hexdump_buf_key(MSG_MSGDUMP, "WPS: Decrypted Encrypted Settings",
180 decrypted);
181
182 pos = wpabuf_head_u8(decrypted) + wpabuf_len(decrypted) - 1;
183 pad = *pos;
184 if (pad > wpabuf_len(decrypted)) {
185 wpa_printf(MSG_DEBUG, "WPS: Invalid PKCS#5 v2.0 pad value");
186 wpabuf_free(decrypted);
187 return NULL;
188 }
189 for (i = 0; i < pad; i++) {
190 if (*pos-- != pad) {
191 wpa_printf(MSG_DEBUG, "WPS: Invalid PKCS#5 v2.0 pad "
192 "string");
193 wpabuf_free(decrypted);
194 return NULL;
195 }
196 }
197 decrypted->used -= pad;
198
199 return decrypted;
200 }
201
202
203 /**
204 * wps_pin_checksum - Compute PIN checksum
205 * @pin: Seven digit PIN (i.e., eight digit PIN without the checksum digit)
206 * Returns: Checksum digit
207 */
wps_pin_checksum(unsigned int pin)208 unsigned int wps_pin_checksum(unsigned int pin)
209 {
210 unsigned int accum = 0;
211 while (pin) {
212 accum += 3 * (pin % 10);
213 pin /= 10;
214 accum += pin % 10;
215 pin /= 10;
216 }
217
218 return (10 - accum % 10) % 10;
219 }
220
221
222 /**
223 * wps_pin_valid - Check whether a PIN has a valid checksum
224 * @pin: Eight digit PIN (i.e., including the checksum digit)
225 * Returns: 1 if checksum digit is valid, or 0 if not
226 */
wps_pin_valid(unsigned int pin)227 unsigned int wps_pin_valid(unsigned int pin)
228 {
229 return wps_pin_checksum(pin / 10) == (pin % 10);
230 }
231
232
233 /**
234 * wps_generate_pin - Generate a random PIN
235 * Returns: Eight digit PIN (i.e., including the checksum digit)
236 */
wps_generate_pin(void)237 unsigned int wps_generate_pin(void)
238 {
239 unsigned int val;
240
241 /* Generate seven random digits for the PIN */
242 if (os_get_random((unsigned char *) &val, sizeof(val)) < 0) {
243 struct os_time now;
244 os_get_time(&now);
245 val = os_random() ^ now.sec ^ now.usec;
246 }
247 val %= 10000000;
248
249 /* Append checksum digit */
250 return val * 10 + wps_pin_checksum(val);
251 }
252
253
wps_fail_event(struct wps_context * wps,enum wps_msg_type msg)254 void wps_fail_event(struct wps_context *wps, enum wps_msg_type msg)
255 {
256 union wps_event_data data;
257
258 if (wps->event_cb == NULL)
259 return;
260
261 os_memset(&data, 0, sizeof(data));
262 data.fail.msg = msg;
263 wps->event_cb(wps->cb_ctx, WPS_EV_FAIL, &data);
264 }
265
266
wps_success_event(struct wps_context * wps)267 void wps_success_event(struct wps_context *wps)
268 {
269 if (wps->event_cb == NULL)
270 return;
271
272 wps->event_cb(wps->cb_ctx, WPS_EV_SUCCESS, NULL);
273 }
274
275
wps_pwd_auth_fail_event(struct wps_context * wps,int enrollee,int part)276 void wps_pwd_auth_fail_event(struct wps_context *wps, int enrollee, int part)
277 {
278 union wps_event_data data;
279
280 if (wps->event_cb == NULL)
281 return;
282
283 os_memset(&data, 0, sizeof(data));
284 data.pwd_auth_fail.enrollee = enrollee;
285 data.pwd_auth_fail.part = part;
286 wps->event_cb(wps->cb_ctx, WPS_EV_PWD_AUTH_FAIL, &data);
287 }
288
289
wps_pbc_overlap_event(struct wps_context * wps)290 void wps_pbc_overlap_event(struct wps_context *wps)
291 {
292 if (wps->event_cb == NULL)
293 return;
294
295 wps->event_cb(wps->cb_ctx, WPS_EV_PBC_OVERLAP, NULL);
296 }
297
298
wps_pbc_timeout_event(struct wps_context * wps)299 void wps_pbc_timeout_event(struct wps_context *wps)
300 {
301 if (wps->event_cb == NULL)
302 return;
303
304 wps->event_cb(wps->cb_ctx, WPS_EV_PBC_TIMEOUT, NULL);
305 }
306