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,
40 unsigned int data_len,
44 SilcSocketConnection sock = conn->sock;
46 SilcPacketContext packetdata;
49 unsigned char *id_string;
52 SILC_LOG_DEBUG(("Sending packet to channel"));
54 if (!channel || !channel->hmac ||
55 (!channel->channel_key && !key && !channel->private_keys)) {
56 client->ops->say(client, conn,
57 "Cannot talk to channel: key does not exist");
61 /* Take the key to be used */
62 if (channel->mode & SILC_CHANNEL_MODE_PRIVKEY) {
64 /* Use key application specified */
67 } else if (channel->curr_key) {
68 /* Use current private key */
69 cipher = channel->curr_key->cipher;
70 hmac = channel->curr_key->hmac;
71 } else if (!channel->curr_key && channel->private_keys) {
72 /* Use just some private key since we don't know what to use
73 and private keys are set. */
74 silc_dlist_start(channel->private_keys);
75 key = silc_dlist_get(channel->private_keys);
79 /* Use this key as current private key */
80 channel->curr_key = key;
82 /* Use normal channel key generated by the server */
83 cipher = channel->channel_key;
87 /* Use normal channel key generated by the server */
88 cipher = channel->channel_key;
93 iv_len = silc_cipher_get_block_len(cipher);
94 if (channel->iv[0] == '\0')
95 for (i = 0; i < iv_len; i++) channel->iv[i] =
96 silc_rng_get_byte(client->rng);
98 silc_hash_make(client->md5hash, channel->iv, iv_len, channel->iv);
100 /* Encode the channel payload. This also encrypts the message payload. */
101 payload = silc_channel_message_payload_encode(data_len, data, iv_len,
102 channel->iv, cipher, hmac,
105 /* Get data used in packet header encryption, keys and stuff. */
106 cipher = conn->send_key;
108 id_string = silc_id_id2str(channel->id, SILC_ID_CHANNEL);
110 /* Set the packet context pointers. The destination ID is always
111 the Channel ID of the channel. Server and router will handle the
112 distribution of the packet. */
113 packetdata.flags = 0;
114 packetdata.type = SILC_PACKET_CHANNEL_MESSAGE;
115 packetdata.src_id = conn->local_id_data;
116 packetdata.src_id_len = SILC_ID_CLIENT_LEN;
117 packetdata.src_id_type = SILC_ID_CLIENT;
118 packetdata.dst_id = id_string;
119 packetdata.dst_id_len = SILC_ID_CHANNEL_LEN;
120 packetdata.dst_id_type = SILC_ID_CHANNEL;
121 packetdata.truelen = payload->len + SILC_PACKET_HEADER_LEN +
122 packetdata.src_id_len + packetdata.dst_id_len;
123 packetdata.padlen = SILC_PACKET_PADLEN((SILC_PACKET_HEADER_LEN +
124 packetdata.src_id_len +
125 packetdata.dst_id_len));
127 /* Prepare outgoing data buffer for packet sending */
128 silc_packet_send_prepare(sock,
129 SILC_PACKET_HEADER_LEN +
130 packetdata.src_id_len +
131 packetdata.dst_id_len,
135 packetdata.buffer = sock->outbuf;
137 /* Put the channel message payload to the outgoing data buffer */
138 silc_buffer_put(sock->outbuf, payload->data, payload->len);
140 /* Create the outgoing packet */
141 silc_packet_assemble(&packetdata);
143 /* Encrypt the header and padding of the packet. This is encrypted
144 with normal session key shared with our server. */
145 silc_packet_encrypt(cipher, hmac, sock->outbuf, SILC_PACKET_HEADER_LEN +
146 packetdata.src_id_len + packetdata.dst_id_len +
149 SILC_LOG_HEXDUMP(("Packet to channel, len %d", sock->outbuf->len),
150 sock->outbuf->data, sock->outbuf->len);
152 /* Now actually send the packet */
153 silc_client_packet_send_real(client, sock, force_send);
154 silc_buffer_free(payload);
155 silc_free(id_string);
158 /* Process received message to a channel (or from a channel, really). This
159 decrypts the channel message with channel specific key and parses the
160 channel payload. Finally it displays the message on the screen. */
162 void silc_client_channel_message(SilcClient client,
163 SilcSocketConnection sock,
164 SilcPacketContext *packet)
166 SilcClientConnection conn = (SilcClientConnection)sock->user_data;
167 SilcBuffer buffer = packet->buffer;
168 SilcChannelMessagePayload payload = NULL;
169 SilcChannelID *id = NULL;
170 SilcChannelEntry channel;
172 SilcIDCacheEntry id_cache = NULL;
173 SilcClientID *client_id = NULL;
175 unsigned char *message;
177 SILC_LOG_DEBUG(("Start"));
180 if (packet->dst_id_type != SILC_ID_CHANNEL)
183 client_id = silc_id_str2id(packet->src_id, packet->src_id_len,
187 id = silc_id_str2id(packet->dst_id, packet->dst_id_len, SILC_ID_CHANNEL);
191 /* Find the channel entry from channels on this connection */
192 if (!silc_idcache_find_by_id_one(conn->channel_cache, (void *)id,
193 SILC_ID_CHANNEL, &id_cache))
196 channel = (SilcChannelEntry)id_cache->context;
198 /* If there is no channel private key then just decrypt the message
199 with the channel key. If private keys are set then just go through
200 all private keys and check what decrypts correctly. */
201 if (!(channel->mode & SILC_CHANNEL_MODE_PRIVKEY)) {
202 /* Parse the channel message payload. This also decrypts the payload */
203 payload = silc_channel_message_payload_parse(buffer, channel->channel_key,
207 } else if (channel->private_keys) {
208 SilcChannelPrivateKey entry;
210 silc_dlist_start(channel->private_keys);
211 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
212 /* Parse the channel message payload. This also decrypts the payload */
213 payload = silc_channel_message_payload_parse(buffer, entry->cipher,
218 if (entry == SILC_LIST_END)
224 message = silc_channel_message_get_data(payload, NULL);
226 /* Find client entry */
227 silc_list_start(channel->clients);
228 while ((chu = silc_list_get(channel->clients)) != SILC_LIST_END) {
229 if (!SILC_ID_CLIENT_COMPARE(chu->client->id, client_id)) {
235 /* Pass the message to application */
236 client->ops->channel_message(client, conn, found ? chu->client : NULL,
243 silc_free(client_id);
245 silc_channel_message_payload_free(payload);
248 /* Saves channel key from encoded `key_payload'. This is used when we
249 receive Channel Key Payload and when we are processing JOIN command
252 void silc_client_save_channel_key(SilcClientConnection conn,
253 SilcBuffer key_payload,
254 SilcChannelEntry channel)
256 unsigned char *id_string, *key, *cipher, hash[32];
257 unsigned int tmp_len;
259 SilcIDCacheEntry id_cache = NULL;
260 SilcChannelKeyPayload payload;
262 payload = silc_channel_key_payload_parse(key_payload);
266 id_string = silc_channel_key_get_id(payload, &tmp_len);
268 silc_channel_key_payload_free(payload);
272 id = silc_id_str2id(id_string, tmp_len, SILC_ID_CHANNEL);
274 silc_channel_key_payload_free(payload);
280 if (!silc_idcache_find_by_id_one(conn->channel_cache, (void *)id,
281 SILC_ID_CHANNEL, &id_cache))
284 /* Get channel entry */
285 channel = (SilcChannelEntry)id_cache->context;
289 key = silc_channel_key_get_key(payload, &tmp_len);
290 cipher = silc_channel_key_get_cipher(payload, NULL);
291 channel->key_len = tmp_len * 8;
292 channel->key = silc_calloc(tmp_len, sizeof(*channel->key));
293 memcpy(channel->key, key, tmp_len);
295 if (!silc_cipher_alloc(cipher, &channel->channel_key)) {
296 conn->client->ops->say(conn->client, conn,
297 "Cannot talk to channel: unsupported cipher %s", cipher);
301 /* Set the cipher key */
302 silc_cipher_set_key(channel->channel_key, key, channel->key_len);
304 /* Generate HMAC key from the channel key data and set it */
306 silc_hmac_alloc("hmac-sha1-96", NULL, &channel->hmac);
307 silc_hash_make(channel->hmac->hash, key, tmp_len, hash);
308 silc_hmac_set_key(channel->hmac, hash, silc_hash_len(channel->hmac->hash));
309 memset(hash, 0, sizeof(hash));
311 /* Client is now joined to the channel */
312 channel->on_channel = TRUE;
316 silc_channel_key_payload_free(payload);
319 /* Processes received key for channel. The received key will be used
320 to protect the traffic on the channel for now on. Client must receive
321 the key to the channel before talking on the channel is possible.
322 This is the key that server has generated, this is not the channel
323 private key, it is entirely local setting. */
325 void silc_client_receive_channel_key(SilcClient client,
326 SilcSocketConnection sock,
329 SILC_LOG_DEBUG(("Received key for channel"));
332 silc_client_save_channel_key(sock->user_data, packet, NULL);
335 /* Adds private key for channel. This may be set only if the channel's mode
336 mask includes the SILC_CHANNEL_MODE_PRIVKEY. This returns FALSE if the
337 mode is not set. When channel has private key then the messages are
338 encrypted using that key. All clients on the channel must also know the
339 key in order to decrypt the messages. However, it is possible to have
340 several private keys per one channel. In this case only some of the
341 clients on the channel may know the one key and only some the other key.
343 if `cipher' and/or `hmac' is NULL then default values will be used
344 (aes-256-cbc for cipher and hmac-sha1-96 for hmac).
346 The private key for channel is optional. If it is not set then the
347 channel messages are encrypted using the channel key generated by the
348 server. However, setting the private key (or keys) for the channel
349 significantly adds security. If more than one key is set the library
350 will automatically try all keys at the message decryption phase. Note:
351 setting many keys slows down the decryption phase as all keys has to
352 be tried in order to find the correct decryption key. However, setting
353 a few keys does not have big impact to the decryption performace.
355 NOTE: that this is entirely local setting. The key set using this function
356 is not sent to the network at any phase.
358 NOTE: If the key material was originated by the SKE protocol (using
359 silc_client_send_key_agreement) then the `key' MUST be the
360 key->send_enc_key as this is dictated by the SILC protocol. However,
361 currently it is not expected that the SKE key material would be used
362 as channel private key. However, this API allows it. */
364 int silc_client_add_channel_private_key(SilcClient client,
365 SilcClientConnection conn,
366 SilcChannelEntry channel,
370 unsigned int key_len)
372 SilcChannelPrivateKey entry;
373 unsigned char hash[32];
375 if (!(channel->mode & SILC_CHANNEL_MODE_PRIVKEY))
379 cipher = "aes-256-cbc";
381 hmac = "hmac-sha1-96";
383 if (!silc_cipher_is_supported(cipher))
386 if (!silc_hmac_is_supported(hmac))
389 /* Remove the current key, if it exists. */
390 if (channel->channel_key) {
391 silc_cipher_free(channel->channel_key);
392 memset(channel->key, 0, channel->key_len / 8);
393 silc_free(channel->key);
394 channel->channel_key = NULL;
396 channel->key_len = 0;
399 silc_hmac_free(channel->hmac);
401 if (!channel->private_keys)
402 channel->private_keys = silc_dlist_init();
405 entry = silc_calloc(1, sizeof(*entry));
406 entry->key = silc_calloc(key_len, sizeof(*entry->key));
407 memcpy(entry->key, key, key_len);
408 entry->key_len = key_len;
410 /* Allocate the cipher and set the key*/
411 silc_cipher_alloc(cipher, &entry->cipher);
412 silc_cipher_set_key(entry->cipher, key, key_len * 8);
414 /* Generate HMAC key from the channel key data and set it */
415 silc_hmac_alloc(hmac, NULL, &entry->hmac);
416 silc_hash_make(entry->hmac->hash, key, key_len, hash);
417 silc_hmac_set_key(entry->hmac, hash, silc_hash_len(entry->hmac->hash));
418 memset(hash, 0, sizeof(hash));
420 /* Add to the private keys list */
421 silc_dlist_add(channel->private_keys, entry);
423 if (!channel->curr_key)
424 channel->curr_key = entry;
429 /* Removes all private keys from the `channel'. The old channel key is used
430 after calling this to protect the channel messages. Returns FALSE on
431 on error, TRUE otherwise. */
433 int silc_client_del_channel_private_keys(SilcClient client,
434 SilcClientConnection conn,
435 SilcChannelEntry channel)
437 SilcChannelPrivateKey entry;
439 if (!channel->private_keys)
442 silc_dlist_start(channel->private_keys);
443 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
444 silc_dlist_del(channel->private_keys, entry);
445 memset(entry->key, 0, entry->key_len);
446 silc_free(entry->key);
447 silc_cipher_free(entry->cipher);
448 silc_hmac_free(entry->hmac);
452 channel->curr_key = NULL;
454 silc_dlist_uninit(channel->private_keys);
455 channel->private_keys = NULL;
460 /* Removes and frees private key `key' from the channel `channel'. The `key'
461 is retrieved by calling the function silc_client_list_channel_private_keys.
462 The key is not used after this. If the key was last private key then the
463 old channel key is used hereafter to protect the channel messages. This
464 returns FALSE on error, TRUE otherwise. */
466 int silc_client_del_channel_private_key(SilcClient client,
467 SilcClientConnection conn,
468 SilcChannelEntry channel,
469 SilcChannelPrivateKey key)
471 SilcChannelPrivateKey entry;
473 if (!channel->private_keys)
476 silc_dlist_start(channel->private_keys);
477 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
479 if (channel->curr_key == entry)
480 channel->curr_key = NULL;
482 silc_dlist_del(channel->private_keys, entry);
483 memset(entry->key, 0, entry->key_len);
484 silc_free(entry->key);
485 silc_cipher_free(entry->cipher);
486 silc_hmac_free(entry->hmac);
489 if (silc_dlist_count(channel->private_keys) == 0) {
490 silc_dlist_uninit(channel->private_keys);
491 channel->private_keys = NULL;
501 /* Returns array (pointers) of private keys associated to the `channel'.
502 The caller must free the array by calling the function
503 silc_client_free_channel_private_keys. The pointers in the array may be
504 used to delete the specific key by giving the pointer as argument to the
505 function silc_client_del_channel_private_key. */
507 SilcChannelPrivateKey *
508 silc_client_list_channel_private_keys(SilcClient client,
509 SilcClientConnection conn,
510 SilcChannelEntry channel,
511 unsigned int *key_count)
513 SilcChannelPrivateKey *keys = NULL, entry;
514 unsigned int count = 0;
516 if (!channel->private_keys)
519 silc_dlist_start(channel->private_keys);
520 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
521 keys = silc_realloc(keys, sizeof(*keys) * (count + 1));
532 /* Frees the SilcChannelPrivateKey array. */
534 void silc_client_free_channel_private_keys(SilcChannelPrivateKey *keys,
535 unsigned int key_count)