1/*
2 * Wi-Fi Protected Setup - attribute building
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 "dh_groups.h"
19#include "sha256.h"
20#include "aes_wrap.h"
21#include "wps_i.h"
22
23
24int wps_build_public_key(struct wps_data *wps, struct wpabuf *msg)
25{
26	struct wpabuf *pubkey;
27
28	wpa_printf(MSG_DEBUG, "WPS:  * Public Key");
29	pubkey = dh_init(dh_groups_get(WPS_DH_GROUP), &wps->dh_privkey);
30	pubkey = wpabuf_zeropad(pubkey, 192);
31	if (pubkey == NULL) {
32		wpa_printf(MSG_DEBUG, "WPS: Failed to initialize "
33			   "Diffie-Hellman handshake");
34		return -1;
35	}
36
37	wpabuf_put_be16(msg, ATTR_PUBLIC_KEY);
38	wpabuf_put_be16(msg, wpabuf_len(pubkey));
39	wpabuf_put_buf(msg, pubkey);
40
41	if (wps->registrar) {
42		wpabuf_free(wps->dh_pubkey_r);
43		wps->dh_pubkey_r = pubkey;
44	} else {
45		wpabuf_free(wps->dh_pubkey_e);
46		wps->dh_pubkey_e = pubkey;
47	}
48
49	return 0;
50}
51
52
53int wps_build_req_type(struct wpabuf *msg, enum wps_request_type type)
54{
55	wpa_printf(MSG_DEBUG, "WPS:  * Request Type");
56	wpabuf_put_be16(msg, ATTR_REQUEST_TYPE);
57	wpabuf_put_be16(msg, 1);
58	wpabuf_put_u8(msg, type);
59	return 0;
60}
61
62
63int wps_build_config_methods(struct wpabuf *msg, u16 methods)
64{
65	wpa_printf(MSG_DEBUG, "WPS:  * Config Methods (%x)", methods);
66	wpabuf_put_be16(msg, ATTR_CONFIG_METHODS);
67	wpabuf_put_be16(msg, 2);
68	wpabuf_put_be16(msg, methods);
69	return 0;
70}
71
72
73int wps_build_uuid_e(struct wpabuf *msg, const u8 *uuid)
74{
75	wpa_printf(MSG_DEBUG, "WPS:  * UUID-E");
76	wpabuf_put_be16(msg, ATTR_UUID_E);
77	wpabuf_put_be16(msg, WPS_UUID_LEN);
78	wpabuf_put_data(msg, uuid, WPS_UUID_LEN);
79	return 0;
80}
81
82
83int wps_build_dev_password_id(struct wpabuf *msg, u16 id)
84{
85	wpa_printf(MSG_DEBUG, "WPS:  * Device Password ID (%d)", id);
86	wpabuf_put_be16(msg, ATTR_DEV_PASSWORD_ID);
87	wpabuf_put_be16(msg, 2);
88	wpabuf_put_be16(msg, id);
89	return 0;
90}
91
92
93int wps_build_config_error(struct wpabuf *msg, u16 err)
94{
95	wpa_printf(MSG_DEBUG, "WPS:  * Configuration Error (%d)", err);
96	wpabuf_put_be16(msg, ATTR_CONFIG_ERROR);
97	wpabuf_put_be16(msg, 2);
98	wpabuf_put_be16(msg, err);
99	return 0;
100}
101
102
103int wps_build_authenticator(struct wps_data *wps, struct wpabuf *msg)
104{
105	u8 hash[SHA256_MAC_LEN];
106	const u8 *addr[2];
107	size_t len[2];
108
109	if (wps->last_msg == NULL) {
110		wpa_printf(MSG_DEBUG, "WPS: Last message not available for "
111			   "building authenticator");
112		return -1;
113	}
114
115	/* Authenticator = HMAC-SHA256_AuthKey(M_prev || M_curr*)
116	 * (M_curr* is M_curr without the Authenticator attribute)
117	 */
118	addr[0] = wpabuf_head(wps->last_msg);
119	len[0] = wpabuf_len(wps->last_msg);
120	addr[1] = wpabuf_head(msg);
121	len[1] = wpabuf_len(msg);
122	hmac_sha256_vector(wps->authkey, WPS_AUTHKEY_LEN, 2, addr, len, hash);
123
124	wpa_printf(MSG_DEBUG, "WPS:  * Authenticator");
125	wpabuf_put_be16(msg, ATTR_AUTHENTICATOR);
126	wpabuf_put_be16(msg, WPS_AUTHENTICATOR_LEN);
127	wpabuf_put_data(msg, hash, WPS_AUTHENTICATOR_LEN);
128
129	return 0;
130}
131
132
133int wps_build_version(struct wpabuf *msg)
134{
135	wpa_printf(MSG_DEBUG, "WPS:  * Version");
136	wpabuf_put_be16(msg, ATTR_VERSION);
137	wpabuf_put_be16(msg, 1);
138	wpabuf_put_u8(msg, WPS_VERSION);
139	return 0;
140}
141
142
143int wps_build_msg_type(struct wpabuf *msg, enum wps_msg_type msg_type)
144{
145	wpa_printf(MSG_DEBUG, "WPS:  * Message Type (%d)", msg_type);
146	wpabuf_put_be16(msg, ATTR_MSG_TYPE);
147	wpabuf_put_be16(msg, 1);
148	wpabuf_put_u8(msg, msg_type);
149	return 0;
150}
151
152
153int wps_build_enrollee_nonce(struct wps_data *wps, struct wpabuf *msg)
154{
155	wpa_printf(MSG_DEBUG, "WPS:  * Enrollee Nonce");
156	wpabuf_put_be16(msg, ATTR_ENROLLEE_NONCE);
157	wpabuf_put_be16(msg, WPS_NONCE_LEN);
158	wpabuf_put_data(msg, wps->nonce_e, WPS_NONCE_LEN);
159	return 0;
160}
161
162
163int wps_build_registrar_nonce(struct wps_data *wps, struct wpabuf *msg)
164{
165	wpa_printf(MSG_DEBUG, "WPS:  * Registrar Nonce");
166	wpabuf_put_be16(msg, ATTR_REGISTRAR_NONCE);
167	wpabuf_put_be16(msg, WPS_NONCE_LEN);
168	wpabuf_put_data(msg, wps->nonce_r, WPS_NONCE_LEN);
169	return 0;
170}
171
172
173int wps_build_auth_type_flags(struct wps_data *wps, struct wpabuf *msg)
174{
175	wpa_printf(MSG_DEBUG, "WPS:  * Authentication Type Flags");
176	wpabuf_put_be16(msg, ATTR_AUTH_TYPE_FLAGS);
177	wpabuf_put_be16(msg, 2);
178	wpabuf_put_be16(msg, WPS_AUTH_TYPES);
179	return 0;
180}
181
182
183int wps_build_encr_type_flags(struct wps_data *wps, struct wpabuf *msg)
184{
185	wpa_printf(MSG_DEBUG, "WPS:  * Encryption Type Flags");
186	wpabuf_put_be16(msg, ATTR_ENCR_TYPE_FLAGS);
187	wpabuf_put_be16(msg, 2);
188	wpabuf_put_be16(msg, WPS_ENCR_TYPES);
189	return 0;
190}
191
192
193int wps_build_conn_type_flags(struct wps_data *wps, struct wpabuf *msg)
194{
195	wpa_printf(MSG_DEBUG, "WPS:  * Connection Type Flags");
196	wpabuf_put_be16(msg, ATTR_CONN_TYPE_FLAGS);
197	wpabuf_put_be16(msg, 1);
198	wpabuf_put_u8(msg, WPS_CONN_ESS);
199	return 0;
200}
201
202
203int wps_build_assoc_state(struct wps_data *wps, struct wpabuf *msg)
204{
205	wpa_printf(MSG_DEBUG, "WPS:  * Association State");
206	wpabuf_put_be16(msg, ATTR_ASSOC_STATE);
207	wpabuf_put_be16(msg, 2);
208	wpabuf_put_be16(msg, WPS_ASSOC_NOT_ASSOC);
209	return 0;
210}
211
212
213int wps_build_key_wrap_auth(struct wps_data *wps, struct wpabuf *msg)
214{
215	u8 hash[SHA256_MAC_LEN];
216
217	wpa_printf(MSG_DEBUG, "WPS:  * Key Wrap Authenticator");
218	hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN, wpabuf_head(msg),
219		    wpabuf_len(msg), hash);
220
221	wpabuf_put_be16(msg, ATTR_KEY_WRAP_AUTH);
222	wpabuf_put_be16(msg, WPS_KWA_LEN);
223	wpabuf_put_data(msg, hash, WPS_KWA_LEN);
224	return 0;
225}
226
227
228int wps_build_encr_settings(struct wps_data *wps, struct wpabuf *msg,
229			    struct wpabuf *plain)
230{
231	size_t pad_len;
232	const size_t block_size = 16;
233	u8 *iv, *data;
234
235	wpa_printf(MSG_DEBUG, "WPS:  * Encrypted Settings");
236
237	/* PKCS#5 v2.0 pad */
238	pad_len = block_size - wpabuf_len(plain) % block_size;
239	os_memset(wpabuf_put(plain, pad_len), pad_len, pad_len);
240
241	wpabuf_put_be16(msg, ATTR_ENCR_SETTINGS);
242	wpabuf_put_be16(msg, block_size + wpabuf_len(plain));
243
244	iv = wpabuf_put(msg, block_size);
245	if (os_get_random(iv, block_size) < 0)
246		return -1;
247
248	data = wpabuf_put(msg, 0);
249	wpabuf_put_buf(msg, plain);
250	if (aes_128_cbc_encrypt(wps->keywrapkey, iv, data, wpabuf_len(plain)))
251		return -1;
252
253	return 0;
254}
255