5 Author: Pekka Riikonen <priikone@poseidon.pspt.fi>
7 Copyright (C) 1997 - 2001 Pekka Riikonen
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
21 /* This file includes channel message sending and receiving routines,
22 channel key receiving and setting, and channel private key handling
25 #include "clientlibincludes.h"
26 #include "client_internal.h"
28 /* Sends packet to the `channel'. Packet to channel is always encrypted
29 differently from "normal" packets. SILC header of the packet is
30 encrypted with the next receiver's key and the rest of the packet is
31 encrypted with the channel specific key. Padding and HMAC is computed
32 with the next receiver's key. The `data' is the channel message. If
33 the `force_send' is TRUE then the packet is sent immediately. */
35 void silc_client_send_channel_message(SilcClient client,
36 SilcClientConnection conn,
37 SilcChannelEntry channel,
38 SilcChannelPrivateKey key,
39 SilcMessageFlags flags,
45 SilcSocketConnection sock = conn->sock;
47 SilcPacketContext packetdata;
50 unsigned char *id_string;
53 SILC_LOG_DEBUG(("Sending packet to channel"));
55 /* Take the key to be used */
56 if (channel->mode & SILC_CHANNEL_MODE_PRIVKEY) {
58 /* Use key application specified */
61 } else if (channel->curr_key) {
62 /* Use current private key */
63 cipher = channel->curr_key->cipher;
64 hmac = channel->curr_key->hmac;
65 } else if (!channel->curr_key && channel->private_keys) {
66 /* Use just some private key since we don't know what to use
67 and private keys are set. */
68 silc_dlist_start(channel->private_keys);
69 key = silc_dlist_get(channel->private_keys);
73 /* Use this key as current private key */
74 channel->curr_key = key;
76 /* Use normal channel key generated by the server */
77 cipher = channel->channel_key;
81 /* Use normal channel key generated by the server */
82 cipher = channel->channel_key;
90 iv_len = silc_cipher_get_block_len(cipher);
91 if (channel->iv[0] == '\0')
92 for (i = 0; i < iv_len; i++) channel->iv[i] =
93 silc_rng_get_byte(client->rng);
95 silc_hash_make(client->md5hash, channel->iv, iv_len, channel->iv);
97 /* Encode the channel payload. This also encrypts the message payload. */
98 payload = silc_channel_message_payload_encode(flags, data_len, data, iv_len,
99 channel->iv, cipher, hmac);
101 /* Get data used in packet header encryption, keys and stuff. */
102 cipher = conn->send_key;
103 hmac = conn->hmac_send;
104 id_string = silc_id_id2str(channel->id, SILC_ID_CHANNEL);
106 /* Set the packet context pointers. The destination ID is always
107 the Channel ID of the channel. Server and router will handle the
108 distribution of the packet. */
109 packetdata.flags = 0;
110 packetdata.type = SILC_PACKET_CHANNEL_MESSAGE;
111 packetdata.src_id = conn->local_id_data;
112 packetdata.src_id_len = SILC_ID_CLIENT_LEN;
113 packetdata.src_id_type = SILC_ID_CLIENT;
114 packetdata.dst_id = id_string;
115 packetdata.dst_id_len = SILC_ID_CHANNEL_LEN;
116 packetdata.dst_id_type = SILC_ID_CHANNEL;
117 packetdata.truelen = payload->len + SILC_PACKET_HEADER_LEN +
118 packetdata.src_id_len + packetdata.dst_id_len;
119 packetdata.padlen = SILC_PACKET_PADLEN((SILC_PACKET_HEADER_LEN +
120 packetdata.src_id_len +
121 packetdata.dst_id_len));
123 /* Prepare outgoing data buffer for packet sending */
124 silc_packet_send_prepare(sock,
125 SILC_PACKET_HEADER_LEN +
126 packetdata.src_id_len +
127 packetdata.dst_id_len,
131 packetdata.buffer = sock->outbuf;
133 /* Put the channel message payload to the outgoing data buffer */
134 silc_buffer_put(sock->outbuf, payload->data, payload->len);
136 /* Create the outgoing packet */
137 silc_packet_assemble(&packetdata);
139 /* Encrypt the header and padding of the packet. This is encrypted
140 with normal session key shared with our server. */
141 silc_packet_encrypt(cipher, hmac, sock->outbuf, SILC_PACKET_HEADER_LEN +
142 packetdata.src_id_len + packetdata.dst_id_len +
145 SILC_LOG_HEXDUMP(("Packet to channel, len %d", sock->outbuf->len),
146 sock->outbuf->data, sock->outbuf->len);
148 /* Now actually send the packet */
149 silc_client_packet_send_real(client, sock, force_send, FALSE);
150 silc_buffer_free(payload);
151 silc_free(id_string);
154 /* Process received message to a channel (or from a channel, really). This
155 decrypts the channel message with channel specific key and parses the
156 channel payload. Finally it displays the message on the screen. */
158 void silc_client_channel_message(SilcClient client,
159 SilcSocketConnection sock,
160 SilcPacketContext *packet)
162 SilcClientConnection conn = (SilcClientConnection)sock->user_data;
163 SilcBuffer buffer = packet->buffer;
164 SilcChannelMessagePayload payload = NULL;
165 SilcChannelID *id = NULL;
166 SilcChannelEntry channel;
168 SilcIDCacheEntry id_cache = NULL;
169 SilcClientID *client_id = NULL;
171 unsigned char *message;
173 SILC_LOG_DEBUG(("Start"));
176 if (packet->dst_id_type != SILC_ID_CHANNEL)
179 client_id = silc_id_str2id(packet->src_id, packet->src_id_len,
183 id = silc_id_str2id(packet->dst_id, packet->dst_id_len, SILC_ID_CHANNEL);
187 /* Find the channel entry from channels on this connection */
188 if (!silc_idcache_find_by_id_one(conn->channel_cache, (void *)id,
189 SILC_ID_CHANNEL, &id_cache))
192 channel = (SilcChannelEntry)id_cache->context;
194 /* If there is no channel private key then just decrypt the message
195 with the channel key. If private keys are set then just go through
196 all private keys and check what decrypts correctly. */
197 if (!(channel->mode & SILC_CHANNEL_MODE_PRIVKEY)) {
198 /* Parse the channel message payload. This also decrypts the payload */
199 payload = silc_channel_message_payload_parse(buffer, channel->channel_key,
203 } else if (channel->private_keys) {
204 SilcChannelPrivateKey entry;
206 silc_dlist_start(channel->private_keys);
207 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
208 /* Parse the channel message payload. This also decrypts the payload */
209 payload = silc_channel_message_payload_parse(buffer, entry->cipher,
214 if (entry == SILC_LIST_END)
220 message = silc_channel_message_get_data(payload, NULL);
222 /* Find client entry */
223 silc_list_start(channel->clients);
224 while ((chu = silc_list_get(channel->clients)) != SILC_LIST_END) {
225 if (!SILC_ID_CLIENT_COMPARE(chu->client->id, client_id)) {
231 /* Pass the message to application */
232 client->ops->channel_message(client, conn, found ? chu->client : NULL,
234 silc_channel_message_get_flags(payload),
241 silc_free(client_id);
243 silc_channel_message_payload_free(payload);
246 /* Saves channel key from encoded `key_payload'. This is used when we
247 receive Channel Key Payload and when we are processing JOIN command
250 void silc_client_save_channel_key(SilcClientConnection conn,
251 SilcBuffer key_payload,
252 SilcChannelEntry channel)
254 unsigned char *id_string, *key, *cipher, hash[32];
257 SilcIDCacheEntry id_cache = NULL;
258 SilcChannelKeyPayload payload;
260 payload = silc_channel_key_payload_parse(key_payload);
264 id_string = silc_channel_key_get_id(payload, &tmp_len);
266 silc_channel_key_payload_free(payload);
270 id = silc_id_str2id(id_string, tmp_len, SILC_ID_CHANNEL);
272 silc_channel_key_payload_free(payload);
278 if (!silc_idcache_find_by_id_one(conn->channel_cache, (void *)id,
279 SILC_ID_CHANNEL, &id_cache))
282 /* Get channel entry */
283 channel = (SilcChannelEntry)id_cache->context;
287 key = silc_channel_key_get_key(payload, &tmp_len);
288 cipher = silc_channel_key_get_cipher(payload, NULL);
289 channel->key_len = tmp_len * 8;
290 channel->key = silc_calloc(tmp_len, sizeof(*channel->key));
291 memcpy(channel->key, key, tmp_len);
293 if (!silc_cipher_alloc(cipher, &channel->channel_key)) {
294 conn->client->ops->say(conn->client, conn,
295 "Cannot talk to channel: unsupported cipher %s", cipher);
299 /* Set the cipher key */
300 silc_cipher_set_key(channel->channel_key, key, channel->key_len);
302 /* Generate HMAC key from the channel key data and set it */
304 silc_hmac_alloc("hmac-sha1-96", NULL, &channel->hmac);
305 silc_hash_make(channel->hmac->hash, key, tmp_len, hash);
306 silc_hmac_set_key(channel->hmac, hash, silc_hash_len(channel->hmac->hash));
307 memset(hash, 0, sizeof(hash));
311 silc_channel_key_payload_free(payload);
314 /* Processes received key for channel. The received key will be used
315 to protect the traffic on the channel for now on. Client must receive
316 the key to the channel before talking on the channel is possible.
317 This is the key that server has generated, this is not the channel
318 private key, it is entirely local setting. */
320 void silc_client_receive_channel_key(SilcClient client,
321 SilcSocketConnection sock,
324 SILC_LOG_DEBUG(("Received key for channel"));
327 silc_client_save_channel_key(sock->user_data, packet, NULL);
330 /* Adds private key for channel. This may be set only if the channel's mode
331 mask includes the SILC_CHANNEL_MODE_PRIVKEY. This returns FALSE if the
332 mode is not set. When channel has private key then the messages are
333 encrypted using that key. All clients on the channel must also know the
334 key in order to decrypt the messages. However, it is possible to have
335 several private keys per one channel. In this case only some of the
336 clients on the channel may know the one key and only some the other key.
338 If `cipher' and/or `hmac' is NULL then default values will be used
339 (aes-256-cbc for cipher and hmac-sha1-96 for hmac).
341 The private key for channel is optional. If it is not set then the
342 channel messages are encrypted using the channel key generated by the
343 server. However, setting the private key (or keys) for the channel
344 significantly adds security. If more than one key is set the library
345 will automatically try all keys at the message decryption phase. Note:
346 setting many keys slows down the decryption phase as all keys has to
347 be tried in order to find the correct decryption key. However, setting
348 a few keys does not have big impact to the decryption performace.
350 NOTE: that this is entirely local setting. The key set using this function
351 is not sent to the network at any phase.
353 NOTE: If the key material was originated by the SKE protocol (using
354 silc_client_send_key_agreement) then the `key' MUST be the
355 key->send_enc_key as this is dictated by the SILC protocol. However,
356 currently it is not expected that the SKE key material would be used
357 as channel private key. However, this API allows it. */
359 int silc_client_add_channel_private_key(SilcClient client,
360 SilcClientConnection conn,
361 SilcChannelEntry channel,
367 SilcChannelPrivateKey entry;
368 unsigned char hash[32];
369 SilcSKEKeyMaterial *keymat;
371 if (!(channel->mode & SILC_CHANNEL_MODE_PRIVKEY))
375 cipher = "aes-256-cbc";
377 hmac = "hmac-sha1-96";
379 if (!silc_cipher_is_supported(cipher))
382 if (!silc_hmac_is_supported(hmac))
385 /* Produce the key material */
386 keymat = silc_calloc(1, sizeof(*keymat));
387 if (silc_ske_process_key_material_data(key, key_len, 16, 256, 16,
388 client->md5hash, keymat)
389 != SILC_SKE_STATUS_OK)
392 /* Remove the current key, if it exists. */
393 if (channel->channel_key) {
394 silc_cipher_free(channel->channel_key);
395 memset(channel->key, 0, channel->key_len / 8);
396 silc_free(channel->key);
397 channel->channel_key = NULL;
399 channel->key_len = 0;
402 silc_hmac_free(channel->hmac);
403 channel->hmac = NULL;
406 if (!channel->private_keys)
407 channel->private_keys = silc_dlist_init();
410 entry = silc_calloc(1, sizeof(*entry));
411 entry->key = silc_calloc(keymat->enc_key_len / 8, sizeof(*entry->key));
412 memcpy(entry->key, keymat->send_enc_key, keymat->enc_key_len / 8);
413 entry->key_len = keymat->enc_key_len / 8;
415 /* Allocate the cipher and set the key*/
416 silc_cipher_alloc(cipher, &entry->cipher);
417 silc_cipher_set_key(entry->cipher, entry->key, keymat->enc_key_len);
419 /* Generate HMAC key from the channel key data and set it */
420 silc_hmac_alloc(hmac, NULL, &entry->hmac);
421 silc_hash_make(entry->hmac->hash, entry->key, entry->key_len, hash);
422 silc_hmac_set_key(entry->hmac, hash, silc_hash_len(entry->hmac->hash));
423 memset(hash, 0, sizeof(hash));
425 /* Add to the private keys list */
426 silc_dlist_add(channel->private_keys, entry);
428 if (!channel->curr_key)
429 channel->curr_key = entry;
431 /* Free the key material */
432 silc_ske_free_key_material(keymat);
437 /* Removes all private keys from the `channel'. The old channel key is used
438 after calling this to protect the channel messages. Returns FALSE on
439 on error, TRUE otherwise. */
441 int silc_client_del_channel_private_keys(SilcClient client,
442 SilcClientConnection conn,
443 SilcChannelEntry channel)
445 SilcChannelPrivateKey entry;
447 if (!channel->private_keys)
450 silc_dlist_start(channel->private_keys);
451 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
452 silc_dlist_del(channel->private_keys, entry);
453 memset(entry->key, 0, entry->key_len);
454 silc_free(entry->key);
455 silc_cipher_free(entry->cipher);
456 silc_hmac_free(entry->hmac);
460 channel->curr_key = NULL;
462 silc_dlist_uninit(channel->private_keys);
463 channel->private_keys = NULL;
468 /* Removes and frees private key `key' from the channel `channel'. The `key'
469 is retrieved by calling the function silc_client_list_channel_private_keys.
470 The key is not used after this. If the key was last private key then the
471 old channel key is used hereafter to protect the channel messages. This
472 returns FALSE on error, TRUE otherwise. */
474 int silc_client_del_channel_private_key(SilcClient client,
475 SilcClientConnection conn,
476 SilcChannelEntry channel,
477 SilcChannelPrivateKey key)
479 SilcChannelPrivateKey entry;
481 if (!channel->private_keys)
484 silc_dlist_start(channel->private_keys);
485 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
487 if (channel->curr_key == entry)
488 channel->curr_key = NULL;
490 silc_dlist_del(channel->private_keys, entry);
491 memset(entry->key, 0, entry->key_len);
492 silc_free(entry->key);
493 silc_cipher_free(entry->cipher);
494 silc_hmac_free(entry->hmac);
497 if (silc_dlist_count(channel->private_keys) == 0) {
498 silc_dlist_uninit(channel->private_keys);
499 channel->private_keys = NULL;
509 /* Returns array (pointers) of private keys associated to the `channel'.
510 The caller must free the array by calling the function
511 silc_client_free_channel_private_keys. The pointers in the array may be
512 used to delete the specific key by giving the pointer as argument to the
513 function silc_client_del_channel_private_key. */
515 SilcChannelPrivateKey *
516 silc_client_list_channel_private_keys(SilcClient client,
517 SilcClientConnection conn,
518 SilcChannelEntry channel,
521 SilcChannelPrivateKey *keys = NULL, entry;
524 if (!channel->private_keys)
527 silc_dlist_start(channel->private_keys);
528 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
529 keys = silc_realloc(keys, sizeof(*keys) * (count + 1));
540 /* Frees the SilcChannelPrivateKey array. */
542 void silc_client_free_channel_private_keys(SilcChannelPrivateKey *keys,