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_get_len(conn->local_id, SILC_ID_CLIENT);
113 packetdata.src_id_type = SILC_ID_CLIENT;
114 packetdata.dst_id = id_string;
115 packetdata.dst_id_len = silc_id_get_len(channel->id, SILC_ID_CHANNEL);
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 static void silc_client_channel_message_cb(SilcClient client,
155 SilcClientConnection conn,
156 SilcClientEntry *clients,
157 uint32 clients_count,
160 SilcPacketContext *packet = (SilcPacketContext *)context;
163 silc_client_channel_message(client, conn->sock, packet);
164 silc_packet_context_free(packet);
167 /* Process received message to a channel (or from a channel, really). This
168 decrypts the channel message with channel specific key and parses the
169 channel payload. Finally it displays the message on the screen. */
171 void silc_client_channel_message(SilcClient client,
172 SilcSocketConnection sock,
173 SilcPacketContext *packet)
175 SilcClientConnection conn = (SilcClientConnection)sock->user_data;
176 SilcBuffer buffer = packet->buffer;
177 SilcChannelMessagePayload payload = NULL;
178 SilcChannelID *id = NULL;
179 SilcChannelEntry channel;
181 SilcIDCacheEntry id_cache = NULL;
182 SilcClientID *client_id = NULL;
184 unsigned char *message;
186 SILC_LOG_DEBUG(("Start"));
189 if (packet->dst_id_type != SILC_ID_CHANNEL)
192 client_id = silc_id_str2id(packet->src_id, packet->src_id_len,
196 id = silc_id_str2id(packet->dst_id, packet->dst_id_len, SILC_ID_CHANNEL);
200 /* Find the channel entry from channels on this connection */
201 if (!silc_idcache_find_by_id_one(conn->channel_cache, (void *)id, &id_cache))
204 channel = (SilcChannelEntry)id_cache->context;
206 /* If there is no channel private key then just decrypt the message
207 with the channel key. If private keys are set then just go through
208 all private keys and check what decrypts correctly. */
209 if (!(channel->mode & SILC_CHANNEL_MODE_PRIVKEY)) {
210 /* Parse the channel message payload. This also decrypts the payload */
211 payload = silc_channel_message_payload_parse(buffer, channel->channel_key,
214 /* If decryption failed and we have just performed channel key rekey
215 we will use the old key in decryption. If that fails too then we
216 cannot do more and will drop the packet. */
218 if (!channel->old_channel_key)
221 payload = silc_channel_message_payload_parse(buffer,
222 channel->old_channel_key,
227 } else if (channel->private_keys) {
228 SilcChannelPrivateKey entry;
230 silc_dlist_start(channel->private_keys);
231 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
232 /* Parse the channel message payload. This also decrypts the payload */
233 payload = silc_channel_message_payload_parse(buffer, entry->cipher,
238 if (entry == SILC_LIST_END)
244 /* Find client entry */
245 silc_list_start(channel->clients);
246 while ((chu = silc_list_get(channel->clients)) != SILC_LIST_END) {
247 if (SILC_ID_CLIENT_COMPARE(chu->client->id, client_id)) {
254 /* Resolve the client info */
255 silc_client_get_client_by_id_resolve(client, conn, client_id,
256 silc_client_channel_message_cb,
257 silc_packet_context_dup(packet));
261 message = silc_channel_message_get_data(payload, NULL);
263 /* Pass the message to application */
264 client->ops->channel_message(client, conn, chu->client, channel,
265 silc_channel_message_get_flags(payload),
272 silc_free(client_id);
274 silc_channel_message_payload_free(payload);
277 /* Timeout callback that is called after a short period of time after the
278 new channel key has been created. This removes the old channel key all
281 SILC_TASK_CALLBACK(silc_client_save_channel_key_rekey)
283 SilcChannelEntry channel = (SilcChannelEntry)context;
285 if (channel->old_channel_key)
286 silc_cipher_free(channel->old_channel_key);
287 if (channel->old_hmac)
288 silc_hmac_free(channel->old_hmac);
289 channel->old_channel_key = NULL;
290 channel->old_hmac = NULL;
291 channel->rekey_task = NULL;
294 /* Saves channel key from encoded `key_payload'. This is used when we
295 receive Channel Key Payload and when we are processing JOIN command
298 void silc_client_save_channel_key(SilcClientConnection conn,
299 SilcBuffer key_payload,
300 SilcChannelEntry channel)
302 unsigned char *id_string, *key, *cipher, *hmac, hash[32];
305 SilcIDCacheEntry id_cache = NULL;
306 SilcChannelKeyPayload payload;
308 payload = silc_channel_key_payload_parse(key_payload);
312 id_string = silc_channel_key_get_id(payload, &tmp_len);
314 silc_channel_key_payload_free(payload);
318 id = silc_id_str2id(id_string, tmp_len, SILC_ID_CHANNEL);
320 silc_channel_key_payload_free(payload);
326 if (!silc_idcache_find_by_id_one(conn->channel_cache,
327 (void *)id, &id_cache))
330 /* Get channel entry */
331 channel = (SilcChannelEntry)id_cache->context;
334 hmac = channel->hmac ? channel->hmac->hmac->name : SILC_DEFAULT_HMAC;
336 /* Save the old key for a short period of time so that we can decrypt
337 channel message even after the rekey if some client would be sending
338 messages with the old key after the rekey. */
339 if (channel->old_channel_key)
340 silc_cipher_free(channel->old_channel_key);
341 if (channel->old_hmac)
342 silc_hmac_free(channel->old_hmac);
343 if (channel->rekey_task)
344 silc_schedule_task_del(conn->client->schedule, channel->rekey_task);
345 channel->old_channel_key = channel->channel_key;
346 channel->old_hmac = channel->hmac;
347 channel->rekey_task =
348 silc_schedule_task_add(conn->client->schedule, 0,
349 silc_client_save_channel_key_rekey, channel,
350 10, 0, SILC_TASK_TIMEOUT, SILC_TASK_PRI_NORMAL);
352 /* Free the old channel key data */
353 silc_free(channel->key);
356 key = silc_channel_key_get_key(payload, &tmp_len);
357 cipher = silc_channel_key_get_cipher(payload, NULL);
358 channel->key_len = tmp_len * 8;
359 channel->key = silc_calloc(tmp_len, sizeof(*channel->key));
360 memcpy(channel->key, key, tmp_len);
362 if (!silc_cipher_alloc(cipher, &channel->channel_key)) {
363 conn->client->ops->say(conn->client, conn, SILC_CLIENT_MESSAGE_AUDIT,
364 "Cannot talk to channel: unsupported cipher %s",
369 /* Set the cipher key */
370 silc_cipher_set_key(channel->channel_key, key, channel->key_len);
372 /* Generate HMAC key from the channel key data and set it */
373 silc_hmac_alloc(hmac, NULL, &channel->hmac);
374 silc_hash_make(channel->hmac->hash, key, tmp_len, hash);
375 silc_hmac_set_key(channel->hmac, hash, silc_hash_len(channel->hmac->hash));
376 memset(hash, 0, sizeof(hash));
380 silc_channel_key_payload_free(payload);
383 /* Processes received key for channel. The received key will be used
384 to protect the traffic on the channel for now on. Client must receive
385 the key to the channel before talking on the channel is possible.
386 This is the key that server has generated, this is not the channel
387 private key, it is entirely local setting. */
389 void silc_client_receive_channel_key(SilcClient client,
390 SilcSocketConnection sock,
393 SILC_LOG_DEBUG(("Received key for channel"));
396 silc_client_save_channel_key(sock->user_data, packet, NULL);
399 /* Adds private key for channel. This may be set only if the channel's mode
400 mask includes the SILC_CHANNEL_MODE_PRIVKEY. This returns FALSE if the
401 mode is not set. When channel has private key then the messages are
402 encrypted using that key. All clients on the channel must also know the
403 key in order to decrypt the messages. However, it is possible to have
404 several private keys per one channel. In this case only some of the
405 clients on the channel may know the one key and only some the other key.
407 If `cipher' and/or `hmac' is NULL then default values will be used
408 (aes-256-cbc for cipher and hmac-sha1-96 for hmac).
410 The private key for channel is optional. If it is not set then the
411 channel messages are encrypted using the channel key generated by the
412 server. However, setting the private key (or keys) for the channel
413 significantly adds security. If more than one key is set the library
414 will automatically try all keys at the message decryption phase. Note:
415 setting many keys slows down the decryption phase as all keys has to
416 be tried in order to find the correct decryption key. However, setting
417 a few keys does not have big impact to the decryption performace.
419 NOTE: that this is entirely local setting. The key set using this function
420 is not sent to the network at any phase.
422 NOTE: If the key material was originated by the SKE protocol (using
423 silc_client_send_key_agreement) then the `key' MUST be the
424 key->send_enc_key as this is dictated by the SILC protocol. However,
425 currently it is not expected that the SKE key material would be used
426 as channel private key. However, this API allows it. */
428 int silc_client_add_channel_private_key(SilcClient client,
429 SilcClientConnection conn,
430 SilcChannelEntry channel,
436 SilcChannelPrivateKey entry;
437 unsigned char hash[32];
438 SilcSKEKeyMaterial *keymat;
440 if (!(channel->mode & SILC_CHANNEL_MODE_PRIVKEY))
444 cipher = SILC_DEFAULT_CIPHER;
446 hmac = SILC_DEFAULT_HMAC;
448 if (!silc_cipher_is_supported(cipher))
451 if (!silc_hmac_is_supported(hmac))
454 /* Produce the key material */
455 keymat = silc_calloc(1, sizeof(*keymat));
456 if (silc_ske_process_key_material_data(key, key_len, 16, 256, 16,
457 client->md5hash, keymat)
458 != SILC_SKE_STATUS_OK)
461 /* Remove the current key, if it exists. */
462 if (channel->channel_key) {
463 silc_cipher_free(channel->channel_key);
464 memset(channel->key, 0, channel->key_len / 8);
465 silc_free(channel->key);
466 channel->channel_key = NULL;
468 channel->key_len = 0;
471 silc_hmac_free(channel->hmac);
472 channel->hmac = NULL;
475 if (!channel->private_keys)
476 channel->private_keys = silc_dlist_init();
479 entry = silc_calloc(1, sizeof(*entry));
480 entry->key = silc_calloc(keymat->enc_key_len / 8, sizeof(*entry->key));
481 memcpy(entry->key, keymat->send_enc_key, keymat->enc_key_len / 8);
482 entry->key_len = keymat->enc_key_len / 8;
484 /* Allocate the cipher and set the key*/
485 silc_cipher_alloc(cipher, &entry->cipher);
486 silc_cipher_set_key(entry->cipher, entry->key, keymat->enc_key_len);
488 /* Generate HMAC key from the channel key data and set it */
489 silc_hmac_alloc(hmac, NULL, &entry->hmac);
490 silc_hash_make(entry->hmac->hash, entry->key, entry->key_len, hash);
491 silc_hmac_set_key(entry->hmac, hash, silc_hash_len(entry->hmac->hash));
492 memset(hash, 0, sizeof(hash));
494 /* Add to the private keys list */
495 silc_dlist_add(channel->private_keys, entry);
497 if (!channel->curr_key)
498 channel->curr_key = entry;
500 /* Free the key material */
501 silc_ske_free_key_material(keymat);
506 /* Removes all private keys from the `channel'. The old channel key is used
507 after calling this to protect the channel messages. Returns FALSE on
508 on error, TRUE otherwise. */
510 int silc_client_del_channel_private_keys(SilcClient client,
511 SilcClientConnection conn,
512 SilcChannelEntry channel)
514 SilcChannelPrivateKey entry;
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 silc_dlist_del(channel->private_keys, entry);
522 memset(entry->key, 0, entry->key_len);
523 silc_free(entry->key);
524 silc_cipher_free(entry->cipher);
525 silc_hmac_free(entry->hmac);
529 channel->curr_key = NULL;
531 silc_dlist_uninit(channel->private_keys);
532 channel->private_keys = NULL;
537 /* Removes and frees private key `key' from the channel `channel'. The `key'
538 is retrieved by calling the function silc_client_list_channel_private_keys.
539 The key is not used after this. If the key was last private key then the
540 old channel key is used hereafter to protect the channel messages. This
541 returns FALSE on error, TRUE otherwise. */
543 int silc_client_del_channel_private_key(SilcClient client,
544 SilcClientConnection conn,
545 SilcChannelEntry channel,
546 SilcChannelPrivateKey key)
548 SilcChannelPrivateKey entry;
550 if (!channel->private_keys)
553 silc_dlist_start(channel->private_keys);
554 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
556 if (channel->curr_key == entry)
557 channel->curr_key = NULL;
559 silc_dlist_del(channel->private_keys, entry);
560 memset(entry->key, 0, entry->key_len);
561 silc_free(entry->key);
562 silc_cipher_free(entry->cipher);
563 silc_hmac_free(entry->hmac);
566 if (silc_dlist_count(channel->private_keys) == 0) {
567 silc_dlist_uninit(channel->private_keys);
568 channel->private_keys = NULL;
578 /* Returns array (pointers) of private keys associated to the `channel'.
579 The caller must free the array by calling the function
580 silc_client_free_channel_private_keys. The pointers in the array may be
581 used to delete the specific key by giving the pointer as argument to the
582 function silc_client_del_channel_private_key. */
584 SilcChannelPrivateKey *
585 silc_client_list_channel_private_keys(SilcClient client,
586 SilcClientConnection conn,
587 SilcChannelEntry channel,
590 SilcChannelPrivateKey *keys = NULL, entry;
593 if (!channel->private_keys)
596 silc_dlist_start(channel->private_keys);
597 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
598 keys = silc_realloc(keys, sizeof(*keys) * (count + 1));
609 /* Frees the SilcChannelPrivateKey array. */
611 void silc_client_free_channel_private_keys(SilcChannelPrivateKey *keys,