8 .ds RF FORMFEED[Page %]
17 Network Working Group P. Riikonen
19 draft-riikonen-silc-pp-00.txt 28 June 2000
26 <draft-riikonen-silc-pp-00.txt>
31 This document is an Internet-Draft and is in full conformance with
32 all provisions of Section 10 of RFC 2026. Internet-Drafts are
33 working documents of the Internet Engineering Task Force (IETF), its
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35 distribute working documents as Internet-Drafts.
37 Internet-Drafts are draft documents valid for a maximum of six months
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39 time. It is inappropriate to use Internet-Drafts as reference
40 material or to cite them other than as "work in progress."
42 The list of current Internet-Drafts can be accessed at
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45 The list of Internet-Draft Shadow Directories can be accessed at
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48 The distribution of this memo is unlimited.
54 This memo describes a Packet Protocol used in the Secure Internet Live
55 Conferencing (SILC) protocol specified in the Secure Internet Live
56 Conferencing, Protocol Specification Internet Draft [SILC1]. This
57 protocol describes the packet types and packet payloads which defines
58 the contents of the packets. The protocol provides secure binary packet
59 protocol that assures that the contents of the packets are secured and
74 1 Introduction .................................................. 3
75 2 SILC Packet Protocol .......................................... 4
76 2.1 SILC Packet ............................................... 4
77 2.2 SILC Packet Header ........................................ 5
78 2.3 SILC Packet Types ......................................... 7
79 2.3.1 SILC Packet Payloads ................................ 15
80 2.3.2 Disconnect Payload .................................. 15
81 2.3.3 Success Payload ..................................... 16
82 2.3.4 Failure Payload ..................................... 16
83 2.3.5 Reject Payload ...................................... 17
84 2.3.6 Notify Payload ...................................... 17
85 2.3.7 Error Payload ....................................... 18
86 2.3.8 Channel Message Payload ............................. 19
87 2.3.9 Channel Key Payload ................................. 20
88 2.3.10 Private Message Payload ............................ 23
89 2.3.11 Private Message Key Payload ........................ 24
90 2.3.12 Command Payload .................................... 25
91 2.3.12.1 Command Argument Payload .................. 25
92 2.3.13 Command Reply Payload .............................. 26
93 2.3.14 Connection Auth Request Payload .................... 27
94 2.3.15 New ID Payload ..................................... 28
95 2.3.16 New ID List Payload ................................ 29
96 2.3.17 New Client Payload ................................. 29
97 2.3.18 New Server Payload ................................. 31
98 2.3.19 New Channel Payload ................................ 31
99 2.3.20 New Channel User Payload ........................... 32
100 2.3.21 New Channel List Payload ........................... 33
101 2.3.22 New Channel User List Payload ...................... 34
102 2.3.23 Replace ID Payload ................................. 34
103 2.3.24 Remove ID Payload .................................. 35
104 2.4 SILC ID Types ............................................. 36
105 2.5 Packet Encryption And Decryption .......................... 37
106 2.5.1 Normal Packet Encryption And Decryption ............. 37
107 2.5.2 Channel Message Encryption And Decryption ........... 37
108 2.5.3 Private Message Encryption And Decryption ........... 38
109 2.6 Packet MAC Generation ..................................... 39
110 2.7 Packet Padding Generation ................................. 39
111 2.8 Packet Compression ........................................ 40
112 2.9 Packet Sending ............................................ 40
113 2.10 Packet Reception ......................................... 41
114 2.11 Packet Routing ........................................... 42
115 2.12 Packet Forwarding ........................................
116 2.13 Packet Broadcasting ...................................... 41
117 2.14 Packet Tunneling ......................................... 42
118 3 Security Considerations ....................................... 43
119 4 References .................................................... 43
120 5 Author's Address .............................................. 44
126 Figure 1: Typical SILC Packet
127 Figure 2: SILC Packet Header
128 Figure 3: Disconnect Payload
129 Figure 4: Success Payload
130 Figure 5: Failure Payload
131 Figure 6: Reject Payload
132 Figure 7: Notify Payload
133 Figure 8: Error Payload
134 Figure 9: Channel Message Payload
135 Figure 10: Channel Key Payload
136 Figure 11: Private Message Payload
137 Figure 12: Private Message Key Payload
138 Figure 13: Command Payload
139 Figure 14: Command Argument Payload
140 Figure 15: Connection Auth Request Payload
141 Figure 16: New ID Payload
142 Figure 17: New Client Payload
143 Figure 18: New Server Payload
144 Figure 19: New Channel Payload
145 Figure 20: New Channel User Payload
146 Figure 21: Replace ID Payload
147 Figure 22: Remove ID Payload
153 This document describes a Packet Protocol used in the Secure Internet
154 Live Conferencing (SILC) protocol specified in the Secure Internet Live
155 Conferencing, Protocol Specification Internet Draft [SILC1]. This
156 protocol describes the packet types and packet payloads which defines
157 the contents of the packets. The protocol provides secure binary packet
158 protocol that assures that the contents of the packets are secured and
161 The basis of SILC protocol relies in the SILC packets and it is with
162 out a doubt the most important part of the protocol. It is also probably
163 the most complicated part of the protocol. Packets are used all the
164 time in the SILC network to send messages, commands and other information.
165 All packets in SILC network are always encrypted and their integrity
166 is assured by computed MACs. The protocol defines several packet types
167 and packet payloads. Each packet type usually has a specific packet
168 payload that actually defines the contents of the packet. Each packet
169 also includes a default SILC Packet Header that provides sufficient
170 information about the origin of the packet and destination of the
175 2 SILC Packet Protocol
180 SILC packets deliver messages from sender to receiver securely by
181 encrypting important fields of the packet. The packet consists of
182 default SILC Packet Header, Padding, Packet Payload data, and, packet
185 The following diagram illustrates typical SILC packet.
190 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
191 | n bytes | 1 - n bytes | n bytes | n bytes
192 | SILC Header | Padding | Data Payload | MAC
193 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
197 Figure 1: Typical SILC Packet
200 SILC Header is always the first part of the packet and its purpose
201 is to provide information about the packet. It provides for example
202 the packet type, origin of the packet and the destination of the packet.
203 The header is variable in length and first two (2) bytes of the
204 header (thus first two bytes of the packet) are not encrypted. The
205 first two (2) bytes are the length of the packet which is not encrypted.
206 See following section for description of SILC Packet header. Packets
207 without SILC header or with malformed SILC header must be dropped.
209 Padding follows the packet header. The purpose of the padding is to
210 make the packet multiple by eight (8) or by the block size of the
211 cipher used in the encryption, which ever is larger. The maximum
212 length of padding is currently 16 bytes. The padding is always
215 Data payload area follows padding and it is the actual data of the
216 packet. The packet data is the packet payloads defined in this
217 protocol. The data payload area is always encrypted.
219 The last part of SILC packet is the packet MAC that assures the
220 integrity of the packet. The MAC is always computed from the packet
221 before the encryption is applied to the packet. If compression is used
222 in the packet the MAC is computed after the compression has been
223 applied. The compression, on the other hand, is always applied before
226 All fields in all packet payloads are always in MSB (most significant
231 2.2 SILC Packet Header
233 The default SILC packet header is applied to all SILC packets and it is
234 variable in length. The purpose of SILC Packet header is to provide
235 detailed information about the packet. The receiver of the packet uses
236 the packet header to parse the packet and gain other relevant parameters
239 Following diagram represents the default SILC header format.
240 (*) indicates that this field is never encrypted. Other fields are
247 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
248 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
249 | Payload Length * | Flags | Packet Type |
250 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
251 | Source ID Length | Destination ID Length |
252 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
258 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
264 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
268 Figure 2: SILC Packet Header
272 o Payload Length (2 bytes) - Is the length of the packet
273 not including the padding of the packet. This field must
274 not be encrypted but must always be authenticated.
276 o Flags (1 byte) - Indicates flags to be used in packet
277 processing. Several flags may be set by ORing the flags
280 Following flags are reserved for this field:
287 In this case the field is ignored.
290 Private Message Key 0x01
292 Indicates that the packet must include private
293 message that is encrypted using private key set by
294 client. Servers does not know anything about this
295 key and this causes that the private message is
296 not handled by the server at all, it is just
297 passed along. See section 2.5.3 Private Message
298 Encryption And Decryption for more information.
303 Marks the packet to be forwarded. Some specific
304 packet types may be forwarded. Receiver of packet
305 with this flag set must not forward the packet any
306 further. See section 2.12 Packet Forwarding for
307 desribtion of packet forwarding.
312 Marks the packet to be broadcasted. Client cannot
313 send broadcast packet and normal server cannot send
314 broadcast packet. Only router server may send broadcast
315 packet. The router receiving of packet with this flag
316 set must send (broadcast) the packet to its primary
317 route. If router has several router connections the
318 packet may be sent only to the primary route. See
319 section 2.13 Packet Broadcasting for description of
325 Marks that the packet is tunneled. Tunneling means
326 that extra SILC Packet Header has been applied to the
327 original packet. The outer header has this flag
328 set. See section 2.14 Packet Tunneling for more
334 o Packet Type (1 byte) - Is the type of the packet. Receiver
335 uses this field to parse the packet. See section 2.3
336 SILC Packets for list of defined packet types.
338 o Source ID Length (2 bytes) - Indicates the length of the
339 Source ID field in the header, not including this or any
344 o Destination ID Length (2 bytes) - Indicates the length of the
345 Destination ID field in the header, not including this or
348 o Src ID Type (1 byte) - Indicates the type of ID in the
349 Source ID field. See section 2.4 SILC ID Types for
352 o Source ID (variable length) - The actual source ID that
353 indicates who is the original sender of the packet.
355 o Dst ID Type (1 byte) - Indicates the type of ID in the
356 Destination ID field. See section 2.4 SILC ID Types for
359 o Destination ID (variable length) - The actual source ID that
360 indicates who is the end receiver of the packet.
364 2.3 SILC Packet Types
366 SILC packet types defines the contents of the packet and it is used by
367 the receiver to parse the packet. The packet type is 8 bits, as a one
368 byte, in length. The range for the packet types are from 0 - 255,
369 where 0 is never sent and 255 is currently reserved for future
370 extensions and must not be defined to any other purpose. Every SILC
371 specification compliant implementation should support all of these packet
374 The below list of the SILC Packet types includes reference to the packet
375 payload as well. Packet payloads are the actual packet, that is, the data
376 that the packet consists of. Each packet type defines packet payload
377 which usually may only be sent with the specific packet type.
379 Most of the packets are packets that must be destined directly to entity
380 that is connected to the sender. It is not allowed, for example, for
381 router to send disconnect packet to client that is not directly connected
382 to the router. However, there are some special packet types that may
383 be destined to some entity that the sender has not direct connection
384 with. These packets are for example private message packets, channel
385 message packets, command packets and some other packets that may be
386 broadcasted in the SILC network. If the packet is allowed to be sent to
387 indirectly connected entity it is mentioned separately in the packet
388 description (unless it is obvious as in private and channel message
389 packets). Other packets must not be sent or accepted, if sent, to
390 indirectly connected entities.
392 List of SILC Packet types are defined as follows.
397 This type is reserved and it is never sent.
400 1 SILC_PACKET_DISCONNECT
402 This packet is sent to disconnect the remote end. Reason of
403 the disconnection is sent inside the packet payload. Client
404 usually does not send this packet.
406 Payload of the packet: See section 2.3.2 Disconnect Payload
409 2 SILC_PACKET_SUCCESS
411 This packet is sent upon successful execution of some protocol.
412 The status of the success is sent in the packet.
414 Payload of the packet: See section 2.3.3 Success Payload
417 3 SILC_PACKET_FAILURE
419 This packet is sent upon failure of some protocol. The status
420 of the failure is sent in the packet.
422 Payload of the packet: See section 2.3.4 Failure Payload
427 This packet may be sent upon rejection of some protocol.
428 The status of the rejection is sent in the packet.
430 Payload of the packet: See section 2.3.5 Reject Payload
435 This packet is used to send notify message, usually from
436 server to client, although it may be sent from server to another
437 server as well. Client never sends this packet. Server may
438 send this packet to channel as well when the packet is
439 distributed to all clients on the channel. Receiver of this
440 packet may ignore the packet if it chooses so. However, it
441 should not be ignored.
443 Payload of the packet: See section 2.3.6 Notify Payload.
448 This packet is sent when an error occurs. Server may
449 send this packet. Client never sends this packet. The
450 client may entirely ignore the packet, however, server is
451 most likely to take action anyway.
453 Payload of the packet: See section 2.3.7 Error Payload.
456 7 SILC_PACKET_CHANNEL_MESSAGE
458 This packet is used to send messages to channels. The packet
459 includes Channel ID of the channel and the actual message to
460 the channel. Messages sent to the channel are always protected
461 by channel specific keys. Channel Keys are distributed by
462 SILC_PACKET_CHANNEL_KEY packet.
464 When client sends this packet the destination ID in the SILC
465 header must be the Channel ID of the channel the message is
466 destined to. If server sends this packet to a client the
467 destination ID in the SILC header must be the Client ID of
468 the client receiving the packet.
470 If server sends this packet to router or if router sends this
471 packet to server or another router the destination ID in the
472 SILC header must be the Channel ID of the channel. Server
473 (including router) distributes this packet only to its local
474 clients who are joined to the channel. Servers and routers
475 also determines who are on the channel and when this packet
476 needs to be sent, as described in section Client To Client
479 Payload of the packet: See section 2.3.8 Channel Message
483 8 SILC_PACKET_CHANNEL_KEY
485 This packet is used to distribute new key for particular
486 channel. Each channel has their own independent keys that
487 is used to protect the traffic on the channel. Only server
488 may send this packet. This packet may be sent to entity
489 that is indirectly connected to the sender.
491 Payload of the packet: See section 2.3.9 Channel Key Payload
494 9 SILC_PACKET_PRIVATE_MESSAGE
496 This packet is used to send private messages from client
497 to another client. By default, private messages are protected
498 by session keys established by normal key exchange protocol.
499 However, it is possible to use specific key to protect private
500 messages. SILC_PACKET_PRIVATE_MESSAGE_KEY packet is used to
501 agree the key with the remote client. Pre-shared key may be
502 used as well if both of the client knows it, however, it needs
503 to be agreed outside SILC. See more of this in [SILC1].
505 Payload of the packet: See section 2.3.10 Private Message
509 10 SILC_PACKET_PRIVATE_MESSAGE_KEY
511 This packet is used to agree about a key to be used to protect
512 the private messages between two clients. If this is not sent
513 the normal session key is used to protect the private messages
514 inside SILC network. Agreeing to use specific key to protect
515 private messages adds security, as no server between the two
516 clients will be able to decrypt the private message. However,
517 servers inside SILC network are considered to be trusted, thus
518 using normal session key to protect private messages does not
519 degree security. Whether to agree to use specific keys by
520 default or to use normal session keys by default, is
521 implementation specific issue. See more of this in [SILC1].
523 Payload of the packet: See section 2.3.11 Private Message
527 11 SILC_PACKET_COMMAND
529 This packet is used to send commands from client to server.
530 Server may send this packet to other servers as well. All
531 commands are listed in their own section SILC Command Types
532 in [SILC1]. The contents of this packet is command specific.
533 This packet may be sent to entity that is indirectly connected
536 Payload of the packet: See section 2.3.12 Command Payload
539 12 SILC_PACKET_COMMAND_REPLY
541 This packet is send as reply to the SILC_PACKET_COMMAND packet.
542 The contents of this packet is command specific. This packet
543 maybe sent to entity that is indirectly connected to the sender.
545 Payload of the packet: See section 2.3.13 Command Reply
546 Payload and section 2.3.12 Command
550 13 SILC_PACKET_KEY_EXCHANGE
552 This packet is used to start SILC Key Exchange Protocol,
553 described in detail in [SILC3].
555 Payload of the packet: Payload of this packet is described
556 in the section SILC Key Exchange
557 Protocol and its sub sections in
561 14 SILC_PACKET_KEY_EXCHANGE_1
563 This packet is used as part of the SILC Key Exchange Protocol.
565 Payload of the packet: Payload of this packet is described
566 in the section SILC Key Exchange
567 Protocol and its sub sections in
571 15 SILC_PACKET_KEY_EXCHANGE_2
573 This packet is used as part of the SILC Key Exchange Protocol.
575 Payload of the packet: Payload of this packet is described
576 in the section SILC Key Exchange
577 Protocol and its sub sections in
581 16 SILC_PACKET_CONNECTION_AUTH_REQUEST
583 This packet is used to request the authentication method to
584 be used in the SILC Connection Authentication Protocol. If
585 initiator of the protocol does not know the mandatory
586 authentication method this packet is used to determine it.
588 The party receiving this payload must respond with the same
589 packet including the mandatory authentication method.
591 Payload of the packet: See section 2.3.14 Connection Auth
595 17 SILC_PACKET_CONNECTION_AUTH
597 This packet is used to start and perform the SILC Connection
598 Authentication Protocol. This protocol is used to authenticate
599 the connecting party. The protocol is described in detail in
602 Payload of the packet: Payload of this packet is described
603 in the section SILC Authentication
604 Protocol and it sub sections in [SILC].
607 18 SILC_PACKET_NEW_ID
609 This packet is used to distribute new ID's from server to
610 router and from router to all routers in the SILC network.
611 This is used when for example new client is registered to
612 SILC network. The newly created ID's of these operations are
613 distributed by this packet. Only server may send this packet,
614 however, client must be able to receive this packet.
616 Payload of the packet: See section 2.3.15 New ID Payload
619 19 SILC_PACKET_NEW_ID_LIST
621 This packet is used to distribute list of new ID's from
622 server to routers. This is equivalent to previous packet
623 type except that it may include several ID's. Client must
624 not send this packet.
626 Payload of the packet: See section 2.3.16 New ID List
630 20 SILC_PACKET_NEW_CLIENT
632 This packet is used by client to register itself to the
633 SILC network. This is sent after key exchange and
634 authentication protocols has been completed. Client sends
635 various information about itself in this packet.
637 Payload of the packet: See section 2.3.17 New Client Payload
640 21 SILC_PACKET_NEW_SERVER
642 This packet is used by server to register itself to the
643 SILC network. This is sent after key exchange and
644 authentication protocols has been completed. Server sends
645 this to the router it connected to, or, if router was
646 connecting, to the connected router. Server sends
647 its Server ID and other information in this packet.
648 Client must not send or receive this packet.
650 Payload of the packet: See section 2.3.18 New Server Payload
653 22 SILC_PACKET_NEW_CHANNEL
655 This packet is used to notify routers about newly created
656 channel. Channels are always created by the router and it must
657 notify other routers about the created channel. Router sends
658 this packet to its primary route. Client must not send this
659 packet. This packet maybe sent to entity that is indirectly
660 connected to the sender.
662 Payload of the packet: See section 2.3.19 New Channel Payload
665 23 SILC_PACKET_NEW_CHANNEL_USER
667 This packet is used to notify routers about new user on channel.
668 The packet is sent after user has joined to the channel. Server
669 may send this packet to its router and router may send this to
670 its primary router. Client must not send this packet. This
671 packet maybe sent to entity that is indirectly connected to the
674 Payload of the packet: See section 2.3.20 New Channel User
678 24 SILC_PACKET_NEW_CHANNEL_LIST
680 This packet is used to distribute list of created channels
681 from server to routers. This is equivalent to the packet
682 SILC_PACKET_NEW_CHANNEL except that it may include several
683 payloads. Client must not send this packet.
685 Payload of the packet: See section 2.3.21 New Channel List
689 25 SILC_PACKET_NEW_CHANNEL_USER_LIST
691 This packet is used to distribute list of users on specific
692 channel from server to routers. This is equivalent to the
693 packet SILC_PACKET_NEW_CHANNEL_USER except that it may
694 include several payloads. Client must not send this packet.
696 Payload of the packet: See section 2.3.22 New Channel User
700 26 SILC_PACKET_REPLACE_ID
702 This packet is used to replace old ID with new ID sent in
703 the packet payload. For example, when client changes its
704 nickname new ID is created and this packet can be used to
705 distribute the new ID and the old ID is removed when it is
706 send in the packet. Client cannot send or receive this
707 packet. This packet maybe sent to entity that is indirectly
708 connected to the sender.
710 Payload of the packet: See section 2.3.23 Replace ID Payload
713 27 SILC_PACKET_REMOVE_ID
715 This packet is used to removed ID. For example, when client
716 exits SILC network its ID is removed. Client must not send
717 this packet. This packet maybe sent to entity that is
718 indirectly connected to the sender.
720 Payload of the packet: See section 2.3.24 Remove ID Payload
725 This packet is used to indicate that re-key must be performed
726 for session keys. See section Session Key Regeneration in
727 [SILC1] for more information. This packet does not have
733 29 SILC_PACKET_REKEY_DONE
735 This packet is used to indicate that re-key is performed and
736 new keys must be used hereafter. This is sent only if re-key
737 was done without PFS option. If PFS is set, this is not sent
738 as SILC Key Exchange protocol is executed. This packet does
744 Currently undefined commands.
749 This type is reserved for future extensions and currently it
755 2.3.1 SILC Packet Payloads
757 All payloads resides in the main data area of the SILC packet. However
758 all payloads must be at the start of the data area after the default
759 SILC packet header and padding. All fields in the packet payload are
760 always encrypted, as, they reside in the data area of the packet which
763 Payloads described in this section are common payloads that must be
764 accepted anytime during SILC session. Most of the payloads may only
765 be sent with specific packet type which is defined in the description
768 There are a lot of other payloads in the SILC as well. However, they
769 are not common in the sense that they could be sent at any time.
770 These payloads are not described in this section. These are payloads
771 such as SILC Key Exchange payloads and so on. These are described
772 in [SILC1] and [SILC3].
776 2.3.2 Disconnect Payload
778 Disconnect payload is sent upon disconnection. The payload is simple;
779 reason of disconnection is sent to the disconnected party.
781 The payload may only be sent with SILC_PACKET_DISCONNECT packet. It
782 must not be sent in any other packet type. Following diagram represents
783 the Disconnect Payload.
789 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
790 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
792 ~ Disconnect Message ~
794 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
798 Figure 3: Disconnect Payload
804 o Disconnect Message (variable length) - Human readable
805 reason of the disconnection.
810 2.3.3 Success Payload
812 Success payload is sent when some protocol execution is successfully
813 completed. The payload is simple; indication of the success is sent.
814 This maybe any data, including binary or human readable data.
819 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
820 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
822 ~ Success Indication ~
824 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
828 Figure 4: Success Payload
832 o Success Indication (variable length) - Indication of
833 the success. This maybe for example some flag that
834 indicates the protocol and the success status or human
835 readable success message. The true length of this
836 payload is available by calculating it from the SILC
842 2.3.4 Failure Payload
844 This is opposite of Success Payload. Indication of failure of
845 some protocol is sent in the payload.
851 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
852 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
854 ~ Failure Indication ~
856 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
860 Figure 5: Failure Payload
864 o Failure Indication (variable length) - Indication of
865 the failure. This maybe for example some flag that
866 indicates the protocol and the failure status or human
867 readable failure message. The true length of this
868 payload is available by calculating it from the SILC
876 This payload is sent when some protocol is rejected to be executed.
877 Other operations may send this as well that was rejected. The
878 indication of the rejection is sent in the payload. The indication
879 may be binary or human readable data.
885 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
886 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
888 ~ Reject Indication ~
890 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
894 Figure 6: Reject Payload
898 o Reject Indication (variable length) - Indication of
899 the rejection. This maybe for example some flag that
900 indicates the protocol and the rejection status or human
901 readable rejection message. The true length of this
902 payload is available by calculating it from the SILC
913 Notify payload is used to send notify messages. The payload is usually
914 sent from server to client, however, server may send it to another
915 server as well. Client must not send this payload. The receiver of
916 this payload may totally ignore the contents of the payload, however,
917 notify message should be noted and possibly logged.
919 The payload may only be sent with SILC_PACKET_NOTIFY packet. It must
920 not be sent in any other packet type. Following diagram represents the
926 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
927 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
931 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
935 Figure 7: Notify Payload
939 o Notify Message (variable length) - Human readable notify
947 Error payload is sent upon error. Error may occur in various
948 conditions when server sends this packet. Client may not send this
949 payload but must be able to accept it. However, client may
950 totally ignore the contents of the packet as server is going to
951 take action on the error anyway. However, it is recommended
952 that the client takes error packet seriously.
958 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
959 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
963 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
967 Figure 8: Error Payload
971 o Error Message (variable length) - Human readable error
977 2.3.8 Channel Message Payload
979 Channel messages are the most common messages sent in the SILC.
980 Channel Message Payload is used to send message to channels. These
981 messages can only be sent if client has joined to some channel.
982 Even though this packet is the most common in SILC it is still
983 special packet. Some special handling on sending and reception
984 of channel message is required.
986 Padding must be applied into this payload since the payload is
987 encrypted separately from other parts of the packet with the
988 channel specific key. Hence the requirement of the padding.
989 The padding should be random data. The packet must be made
990 multiple by eight (8) or by the block size of the cipher, which
993 The SILC header in this packet is encrypted with the session key
994 of the next receiver of the packet. Nothing else is encrypted
995 with that key. Thus, the actual packet and padding to be
996 encrypted with the session key is SILC Header plus padding to it
997 to make it multiple by eight (8) or multiple by the block size
998 of the cipher, which ever is larger.
1000 Receiver of the the channel message packet is able to determine
1001 the channel the message is destined to by checking the destination
1002 ID from the SILC Packet header which tells the destination channel.
1003 The original sender of the packet is also determined by checking
1004 the source ID from the header which tells the who client sent
1007 The payload may only be sent with SILC_PACKET_CHANNEL_MESSAGE packet.
1008 It must not be sent in any other packet type. Following diagram
1009 represents the Channel Message Payload.
1011 (*) indicates that the field is not encrypted.
1037 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1038 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1039 | Nickname Length | |
1040 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1044 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1045 | Message Length | |
1046 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1050 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1051 | Padding Length | |
1052 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1056 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1058 ~ Initial Vector * ~
1060 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1064 Figure 9: Channel Message Payload
1068 o Nickname Length (2 bytes) - Indicates the length of the
1069 Nickname field, not including any other field.
1071 o Nickname (variable length) - Nickname of the sender of the
1072 channel message. This should not be trusted as a definite
1073 sender of the channel message. The SILC Packet Header in
1074 the packet indicates the true sender of the packet and
1075 client should verify that the nickname sent here belongs
1076 to the Client ID in the SILC Packet Header. This nickname
1077 is merely provided to be displayed by the client.
1079 If server is sending this packet this field is not included
1080 and zero (0) length must be set to the Nickname Length field.
1082 o Message Length (2 bytes) - Indicates the length of the
1083 the Message Data field in the payload, not including any
1087 o Message Data (variable length) - The actual message to
1090 o Padding Length (2 bytes) - Indicates the length of the
1091 Padding field in the payload, not including any other
1094 o Padding (variable length) - The padding that must be
1095 applied because this payload is encrypted separately from
1096 other parts of the packet.
1098 o Initial Vector (variable length) - The initial vector
1099 that has been used in packet encryption. It needs to be
1100 used in the packet decryption as well. What this field
1101 includes is implementation issue. However, it is
1102 recommended that it would be random data or, perhaps,
1103 a timestamp. It is not recommended to use zero (0) as
1104 initial vector. This field is not encrypted. This field
1105 is not included into the padding calculation. Length
1106 of this field equals the cipher's block size. This field
1107 is, however, authenticated.
1112 2.3.9 Channel Key Payload
1114 All traffic in channels are protected by channel specific keys.
1115 Channel Key Payload is used to distribute channel keys to all
1116 clients on the particular channel. Channel keys are sent when
1117 the channel is created, when new user joins to the channel and
1118 whenever a user leaves a channel. Server creates the new
1119 channel key and distributes it to the clients by encrypting this
1120 payload with the session key shared between the server and
1121 the client. After that, client starts using the key received
1122 in this payload to protect the traffic on the channel.
1124 Channel keys are cell specific thus every router in cell have
1125 to create a channel key and distribute it if any client in the
1126 cell has joined to a channel. Channel traffic between cell's
1127 are not encrypted using channel keys, they are encrypted using
1128 normal session keys between two routers. Inside a cell, all
1129 channel traffic is encrypted with the specified channel key.
1130 Channel key should expire peridiocally, say, in one hour, in
1131 which case new channel key is created and distributed.
1133 The payload may only be sent with SILC_PACKET_CHANNEL_KEY packet.
1134 It must not be sent in any other packet type. Following diagram
1135 represents the Channel Key Payload.
1141 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1143 | Channel ID Length | |
1144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1149 | Cipher Name Length | |
1150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1154 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1155 | Channel Key Length | |
1156 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1164 Figure 10: Channel Key Payload
1169 o Channel ID Length (2 bytes) - Indicates the length of the
1170 Channel ID field in the payload, not including any other
1173 o Channel ID (variable length) - The Channel ID of the
1174 channel this key is meant for.
1176 o Cipher Name Length (2 bytes) - Indicates the length of the
1177 Cipher name field in the payload, not including any other
1180 o Cipher Name (variable length) - Name of the cipher used
1181 in the protection of channel traffic. This name is
1182 initially decided by the creator of the channel but it
1183 may change during the life time of the channel as well.
1185 o Channel Key Length (2 bytes) - Indicates the length of the
1186 Channel Key field in the payload, not including any other
1189 o Channel Key (variable length) - The actual channel key
1190 material. This key is used as such as key material for
1191 encryption function.
1196 2.3.10 Private Message Payload
1198 Private Message Payload is used to send private message between
1199 two clients (or users for that matter). The messages are sent only
1200 to the specified user and no other user inside SILC network is
1201 able to see the message. The message is protected by the session
1202 key established by the SILC Key Exchange Protocol. However,
1203 it is also possible to agree to use specific keys to protect
1204 just the private messages. See section 2.3.11 Private Message
1205 Key Payload for detailed description of how to agree to use
1208 If normal session key is used to protect the message, every
1209 server between the sender client and the receiving client needs
1210 to decrypt the packet and always re-encrypt it with the session
1211 key of the next receiver of the packet. See section Client
1212 To Client in [SILC1].
1214 When specific key is used to protect the message, servers between
1215 the sender and the receiver needs not to decrypt/re-encrypt the
1216 packet. Section 4.8.2 Client To Client in [SILC1] gives example of
1217 this scheme as well.
1219 The payload may only be sent with SILC_PACKET_PRIVATE_MESSAGE
1220 packet. It must not be sent in any other packet type. Following
1221 diagram represents the Private Message Payload.
1227 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1228 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1229 | Nickname Length | |
1230 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1234 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1238 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1242 Figure 11: Private Message Payload
1246 o Nickname Length (2 bytes) - Indicates the length of the
1247 Nickname field, not including any other field.
1249 o Nickname (variable length) - Nickname of the sender of the
1250 private message. This should not be trusted as a definite
1251 sender of the private message. The SILC Packet Header in
1252 the packet indicates the true sender of the packet and
1253 client should verify that the nickname sent here belongs
1254 to the Client ID in the SILC Packet Header. This nickname
1255 is merely provided to be displayed by the client.
1257 o Message Data (variable length) - The actual message to
1258 the client. Rest of the packet is reserved for the message
1264 2.3.11 Private Message Key Payload
1266 This payload is used to send key from client to another client that
1267 is going to be used to protect the private messages between these
1268 two clients. If this payload is not sent normal session key
1269 established by the SILC Key Exchange Protocol is used to protect
1270 the private messages.
1272 This payload may only be sent by client to another client. Server
1273 must not send this payload at any time. After sending this payload
1274 the sender of private messages must set the Private Message Key
1275 flag into SILC Packet Header.
1277 The payload may only be sent with SILC_PACKET_PRIVATE_MESSAGE_KEY
1278 packet. It must not be sent in any other packet type. Following
1279 diagram represents the Private Message Key Payload.
1285 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1286 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1287 | Private Message Key Length | |
1288 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1290 ~ Private Message Key ~
1292 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1296 Figure 12: Private Message Key Payload
1302 o Private Message Key Length (2 bytes) - Indicates the length
1303 of the Private Message Key field in the payload, not including
1306 o Private Message Key (variable length) - The actual private
1307 message key material. This key is used as such as key material
1308 for encryption function.
1313 2.3.12 Command Payload
1315 Command Payload is used to send SILC commands from client to server.
1316 Also server may send commands to other servers. Following diagram
1317 represents the Command Payload.
1323 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1324 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1325 | Payload Length | SILC Command | Arguments Num |
1326 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1328 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1332 Figure 13: Command Payload
1336 o Payload Length (2 bytes) - Length of the entire command
1337 payload including any command argument payloads associated
1340 o SILC Command (1 byte) - SILC Command identifier. This must
1341 be set to non-zero value. If zero (0) value is found in this
1342 field the packet must be discarded.
1344 o Arguments Num (1 byte) - Indicates the number of arguments
1345 associated with the command. If there are no arguments this
1346 field is set to zero (0). The arguments must follow the
1349 o Command Unifier (2 bytes) - Unifies this command at the
1350 sender's end. The entity who replies to this command must
1351 set the value found from this field into the Command Payload
1352 used to send the reply to the sender. This way the sender
1353 can identify which command reply belongs to which originally
1354 sent command. What this field includes is implementation
1355 issue but it is recommended that wrapping counter value is
1359 See [SILC1] for detailed description of different SILC commands,
1360 their arguments and their reply messages.
1364 2.3.12.1 Command Argument Payload
1366 Command Argument Payload is used to set arguments for SILC commands.
1367 Number of arguments associated with a command are indicated by the
1368 Command Payload in the Arguments Num field. Command argument
1369 payloads may only be used with a command payload and they must
1370 always reside right after the command payload. Incorrect amount of
1371 argument payloads must cause rejection of the packet. Following
1372 diagram represents the Command Argument Payload.
1378 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1379 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1380 | Argument Num | Argument Type | Payload Length |
1381 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1385 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1389 Figure 14: Command Argument Payload
1393 o Argument Num (1 byte) - Indicates the number of this argument.
1394 For first argument this is set to 1, for second argument this
1395 is set to 2, and so forth. If incorrect value is found
1396 in this field the packet must be discarded. Value is
1397 incorrect if it is zero (0) or, for example, a third argument
1398 does not include value 3.
1400 o Argument Type (1 byte) - Indicates the type of the argument.
1401 Every command specify a number for each argument that maybe
1402 associated with the command. By using this number the receiver
1403 of the packet knows what type of argument this is. The numbers
1404 are command specific and has been defined in section SILC
1405 Commands in [SILC1]. This field makes it possible to send
1406 arguments in free order as this field is used to identify
1407 the specific type of the argument.
1409 o Payload Length (2 bytes) - Length of the argument payload data
1410 area not including the length of any other fields in the
1413 o Argument Data (variable length) - Argument data.
1418 2.3.13 Command Reply Payload
1420 Command Reply Payload is used to send replies to the commands. The
1421 Command Reply Payload is identical to the Command Payload thus see the
1422 upper sections for Command Payload and for Command Argument Payload
1423 specifications. Command Reply message uses the Command Argument Payload
1426 The entity who sends the reply packet must set the Command Unifier
1427 field in the reply packet's Command Payload to the value it received
1428 in the original command packet.
1430 See SILC Commands in [SILC1] for detailed description of different
1431 SILC commands, their arguments and their reply messages.
1435 2.3.14 Connection Auth Request Payload
1437 Client may send this payload to server to request the authentication
1438 method that must be used in authentication protocol. If client knows
1439 this information beforehand this payload is not necessary to be sent.
1440 Server performing authentication with another server may also send
1441 this payload to request the authentication method. If the connecting
1442 server already knows this information this payload is not necessary
1445 Server receiving this request must reply with same payload sending
1446 the mandatory authentication method. Algorithms that may be required
1447 to be used by the authentication method are the ones already
1448 established by the SILC Key Exchange protocol. See section Key
1449 Exchange Start Payload in [SILC3] for detailed information.
1451 The payload may only be sent with SILC_PACKET_CONNECTION_AUTH_REQUEST
1452 packet. It must not be sent in any other packet type. Following
1453 diagram represents the Connection Auth Request Payload.
1459 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1460 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1461 | Connection Type | Authentication Method |
1462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1466 Figure 15: Connection Auth Request Payload
1470 o Connection Type (2 bytes) - Indicates the type of the ID.
1471 Following connection types are defined:
1477 If any other type is found in this field the packet must be
1478 discarded and the authentication must be failed.
1480 o Authentication Method (2 bytes) - Indicates the authentication
1481 method to be used in the authentication protocol. Following
1482 authentication methods are defined:
1487 1 password (mandatory)
1488 2 public key (mandatory)
1490 If any other type is found in this field the packet must be
1491 discarded and the authentication must be failed. If this
1492 payload is sent as request to receive the mandatory
1493 authentication method this field must be set to zero (0),
1494 indicating that receiver should send the mandatory
1495 authentication method. The receiver sending this payload
1496 to the requesting party, may also set this field to zero (0)
1497 to indicate that authentication is not required. In this
1498 case authentication protocol still must be started but
1499 server is most likely to respond with SILC_PACKET_SUCCESS
1505 2.3.15 New ID Payload
1507 New ID Payload is a multipurpose payload. It is used to send newly
1508 created ID's from clients and servers. When client connects to server
1509 and registers itself to the server by sending SILC_PACKET_NEW_CLIENT
1510 packet, server replies with this packet by sending the created ID for
1511 the client. Server always creates the ID for the client.
1513 This payload is also used when server tells its router that new client
1514 has registered to the SILC network. In this case the server sends
1515 the Client ID of the client to the router. Similiary when router
1516 distributes information to other routers about the client in the SILC
1517 network this payload is used.
1519 Also, when server connects to router, router uses this payload to inform
1520 other routers about new server in the SILC network. However, every
1521 server (or router) creates their own ID's thus the ID distributed by
1522 this payload is not created by the distributor in this case. Servers
1523 create their own ID's. Server registers itself to the network by sending
1524 SILC_PACKET_NEW_SERVER to the router it connected to. The case is same
1525 when router connects to another router.
1527 Hence, this payload is very important and used every time when some
1528 new entity is registered to the SILC network. Client never sends this
1529 payload. Both client and server (and router) may receive this payload.
1531 The payload may only be sent with SILC_PACKET_NEW_ID packet. It must
1532 not be sent in any other packet type. Following diagram represents the
1539 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1540 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1541 | ID Type | ID Length |
1542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1546 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1550 Figure 16: New ID Payload
1554 o ID Type (2 bytes) - Indicates the type of the ID. See
1555 section 2.4 SILC ID Types for list of defined ID types.
1557 o ID Length (2 bytes) - Length of the ID Data area not
1558 including the length of any other fields in the payload.
1560 o ID Data (variable length) - The actual ID data.
1566 2.3.16 New ID List Payload
1568 New ID List Payload is used to distribute list of ID's usually from
1569 server to router but also from router to other routers in the network.
1570 This payload is used, for example, when server is connected to router
1571 and the server wants to distribute all of its locally connected clients
1572 and locally created channels to the router. It is convenient in this
1573 case to use this payload instead of sending all the information one
1574 by one using New ID Payload.
1576 There is no specific payload for this packet type. The packet type
1577 uses same payload as described in previous section. To form a list
1578 several payloads is put in the packet each after each. The payload
1579 is variable in length but can be calculated by calculating the ID
1580 Type field, Length field and the ID Data fields together. This forms
1581 one New ID Payload in the list.
1583 The list of payloads may only be sent with SILC_PACKET_NEW_ID_LIST
1584 packet. They must not be sent in any other packet type.
1588 2.3.17 New Client Payload
1590 When client is connected to the server, keys has been exchanged and
1591 connection has been authenticated client must register itself to the
1592 server. Clients first packet after key exchange and authentication
1593 protocols must be SILC_PACKET_NEW_CLIENT. This payload tells server all
1594 the relevant information about the connected user. Server creates a new
1595 client ID for the client when received this payload and sends it to the
1596 client in New ID Payload.
1598 This payload sends username and real name of the user on the remote host
1599 which is connected to the SILC server with SILC client. The server
1600 creates the client ID according the information sent in this payload.
1601 The nickname of the user becomes the username sent in this payload.
1602 However, client should call NICK command after sending this payload to
1603 set the real nickname of the user which is then used to create new
1606 The payload may only be sent with SILC_PACKET_NEW_CLIENT packet. It
1607 must not be sent in any other packet type. Following diagram represents
1608 the New Client Payload.
1614 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1615 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1616 | Username Length | |
1617 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1621 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1622 | Real Name Length | |
1623 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1627 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1631 Figure 17: New Client Payload
1635 o Username Length (2 bytes) - Length of the username.
1637 o Username (variable length) - The username of the user on
1638 the host where connecting to the SILC server.
1640 o Real Name Length (2 bytes) - Length of the Real Name.
1642 o Real Name (variable length) - The real name of the user
1643 on the host where connecting to the SILC server.
1648 2.3.18 New Server Payload
1650 This payload is sent by server when it has completed successfully both
1651 key exchange and connection authentication protocols. The server
1652 uses this payload to register itself to the SILC network. The
1653 first packet after these key exchange and authentication protocols
1654 is SILC_PACKET_NEW_SERVER packet. The payload includes the Server ID
1655 of the server that it has created by itself. It also includes a
1656 name of the server that is associated to the Server ID.
1658 The payload may only be sent with SILC_PACKET_NEW_SERVER packet. It
1659 must not be sent in any other packet type. Following diagram represents
1660 the New Server Payload.
1666 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1667 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1668 | Server ID Length | |
1669 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1673 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1674 | Server Name Length | |
1675 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1679 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1683 Figure 18: New Server Payload
1687 o Server ID Length (2 bytes) - Length of the ID Data area not
1688 including the length of any other fields in the payload.
1690 o Server ID Data (variable length) - The actual Server ID
1693 o Server Name Length (2 bytes) - Length of the server name.
1695 o Server Name (variable length) - The server name.
1700 2.3.19 New Channel Payload
1702 Information about newly created channel is broadcasted to all routers
1703 in the SILC network by sending this packet payload. Channels are
1704 created by router of the cell. Server never creates channels unless
1705 it is a standalone server and it does not have router connection,
1706 in this case server acts as router. Normal server forwards JOIN command
1707 to the router (after it has received JOIN command from client) which
1708 then processes the command and creates the channel. Client never sends
1711 The payload may only be sent with SILC_PACKET_NEW_CHANNEL packet.
1712 It must not be sent in any other packet type. Following diagram
1713 represents the New Channel Payload.
1719 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1720 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1721 | Channel Name Length | |
1722 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1726 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1727 | Channel ID Length | |
1728 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1732 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1736 Figure 19: New Channel Payload
1741 o Channel Name Length (2 bytes) - Length of the channel name.
1743 o Channel Name (variable length) - The name of the created
1746 o Channel ID Length (2 bytes) - Length of the Channel ID.
1748 o Channel ID (variable length) - The created Channel ID.
1753 2.3.20 New Channel User Payload
1755 When client (user) joins to a channel, server must notify routers
1756 about the new user on the channel. Normal server sends this packet
1757 payload to its router which then broadcasts the packet further.
1758 Router sends this packet always to its primary router. Client must
1759 not send this packet payload. The mode of the user is NONE after
1760 user has joined to the channel.
1762 The payload may only be sent with SILC_PACKET_NEW_CHANNEL_USER
1763 packet. It must not be sent in any other packet type. Following
1764 diagram represents the New Channel User Payload.
1770 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1771 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1772 | Channel ID Length | |
1773 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1777 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1778 | Client ID Length | |
1779 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1783 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1787 Figure 20: New Channel User Payload
1791 o Channel ID Length (2 bytes) - Length of the Channel ID.
1793 o Channel ID (variable length) - The Channel ID of the channel
1794 to which the client has joined.
1796 o Client ID Length (2 bytes) - Length of the Client ID.
1798 o Client ID (variable length) - The Client ID of the client
1799 who has joined the channel.
1804 2.3.21 New Channel List Payload
1806 This payload is used to distribute list of new channels from server
1807 to routers. It might convenient to send list of new channels when
1808 existing server connects to router, instead of sending them one
1811 There is no specific payload for this packet type. The packet type
1812 uses same payload as described in 2.3.19 New Channel Payload. To form
1813 a list several payloads is put in the packet each after each. The
1814 payload is variable in length but can be calculated by calculating
1815 the length of the fields together. This forms one New Channel Payload
1818 The list of payloads may only be sent with SILC_PACKET_NEW_CHANNEL_LIST
1819 packet. They must not be sent in any other packet type.
1823 2.3.22 New Channel User List Payload
1825 This payload is used to distribute list of channel users on specific
1826 channel from server to routers. It might convenient to send list of
1827 channel users when existing server connects to router, instead of
1828 sending them one by one.
1830 There is no specific payload for this packet type. The packet type
1831 uses same payload as described in 2.3.20 New Channel User Payload.
1832 To form a list several payloads is put in the packet each after each.
1833 The payload is variable in length but can be calculated by calculating
1834 the length of the fields together. This forms one New Channel User
1835 Payload in the list.
1837 The list of payloads may only be sent with packet
1838 SILC_PACKET_NEW_CHANNEL_USER_LIST. They must not be sent in any other
1843 2.3.23 Replace ID Payload
1845 This payload is used to replace old ID with new ID sent in the payload.
1846 When ID changes for some entity and the new ID is wanted to replace the
1847 old one this payload must be used. Client cannot send or receive this
1848 payload. Normal server and router server may send and receive this
1849 payload. After this packet has been sent the old ID must not be used
1852 The payload may only be sent with SILC_PACKET_REPLACE_ID packet. It must
1853 not be sent in any other packet type. Following diagram represents the
1854 Replace Payload Payload.
1867 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1868 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1869 | Old ID Type | Old ID Length |
1870 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1874 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1875 | New ID Type | New ID Length |
1876 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1880 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1884 Figure 21: Replace ID Payload
1888 o Old ID Type (2 bytes) - Indicates the type of the old ID. See
1889 section 2.4 SILC ID Types for list of defined ID types.
1891 o Old ID Length (2 bytes) - Length of the old ID Data area not
1892 including the length of any other fields in the payload.
1894 o Old ID Data (variable length) - The actual old ID data.
1896 o New ID Type (2 bytes) - Indicates the type of the new ID. See
1897 section 2.4 SILC ID Types for list of defined ID types.
1899 o New ID Length (2 bytes) - Length of the new ID Data area not
1900 including the length of any other fields in the payload.
1902 o New ID Data (variable length) - The actual new ID data.
1907 2.3.24 Remove ID Payload
1909 Remove ID payload is used to remove ID from SILC network. This is used
1910 for example when client exits SILC network. The server must in this
1911 case send this payload to notify that this ID is not valid anymore.
1912 After this has been send the old ID must not be used anymore. Client
1913 must not send this payload.
1915 The payload may only be sent with SILC_PACKET_REMOVE_ID packet. It must
1916 not be sent in any other packet type. Following diagram represents the
1917 Remove Payload Payload.
1923 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1924 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1925 | ID Type | ID Length |
1926 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1930 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1934 Figure 22: Remove ID Payload
1938 o ID Type (2 bytes) - Indicates the type of the ID to be
1939 removed. See section 2.4 SILC ID Types for list of defined
1942 o ID Length (2 bytes) - Length of the D Data area not including
1943 the length of any other fields in the payload.
1945 o ID Data (variable length) - The actual ID data to be removed.
1952 ID's are extensively used in the SILC network to associate different
1953 entities. Following ID's has been defined to be used in the SILC
1959 When ever specific ID cannot be used this is used.
1963 Server ID to associate servers. See the format of
1968 Client ID to associate clients. See the format of
1973 Channel ID to associate channels. See the format of
1979 2.5 Packet Encryption And Decryption
1981 SILC packets are encrypted almost entirely. Only small part of SILC
1982 header is not encrypted as described in section 5.2 SILC Packet Header.
1983 The SILC Packet header is the first part of a packet to be encrypted
1984 and it is always encrypted with the key of the next receiver of the
1985 packet. The data payload area of the packet is always entirely
1986 encrypted and it is usually encrypted with the next receiver's key.
1987 However, there are some special packet types and packet payloads
1988 that require special encryption process. These special cases are
1989 described in the next sections. First is described the normal packet
1994 2.5.1 Normal Packet Encryption And Decryption
1996 Normal SILC packets are encrypted with the session key of the next
1997 receiver of the packet. The entire SILC Packet header and the packet
1998 data payload is is also encrypted with the same key. Padding of the
1999 packet is also encrypted always with the session key, also in special
2000 cases. Computed MAC of the packet must not be encrypted.
2002 Decryption process in these cases are straightforward. The receiver
2003 of the packet must first decrypt the SILC Packet header, or some parts
2004 of it, usually first 16 bytes of it. Then the receiver checks the
2005 packet type from the decrypted part of the header and can determine
2006 how the rest of the packet must be decrypted. If the packet type is
2007 any of the special cases described in following sections the packet
2008 decryption is special. If the packet type is not among those special
2009 packet types rest of the packet may be decrypted with the same key.
2011 Also, note that two bytes of the SILC Packet header are not encrypted
2012 thus it must be noticed in the decryption process by starting the
2013 decryption from the second byte of the header. This sets some rules
2014 to padding generation as well, see the section 2.7 Packet Padding
2017 With out a doubt, this sort of decryption processing causes some
2018 overhead to packet decryption, but never the less, is required.
2022 2.5.2 Channel Message Encryption And Decryption
2024 Channel Messages (Channel Message Payload) are always encrypted with
2025 the channel specific key. However, the SILC Packet header is not
2026 encrypted with that key. As in normal case, the header is encrypted
2027 with the key of the next receiver of the packet, who ever that might
2028 be. Note that in this case the encrypted data area is not touched
2029 at all; it must not be re-encrypted with the session key.
2031 Receiver of a channel message, who ever that is, is required to decrypt
2032 the SILC Packet header to be able to even recognize the packet to be as
2033 channel message. This is same procedure as for normal SILC packets.
2034 As the receiver founds the packet to be channel message, rest of the
2035 packet processing is special. Rest of the SILC Packet header is
2036 decrypted with the same session key along with the padding of the
2037 packet. After that the packet is protected with the channel specific
2038 key and hence can be decrypted only if the receiver is the client on
2039 the channel. See section 2.7 Packet Padding Generation for more
2040 information about padding on special packets.
2042 If the receiver of the channel message is router who is routing the
2043 message to another router then it must decrypt the Channel Message
2044 payload. Between routers (that is, between cells) channel messages
2045 are protected with session keys shared between the routers. This
2046 causes another special packet processing for channel messages. If
2047 the channel message is received from another router then the entire
2048 packet, including Channel Message payload, is encrypted with the
2049 session key shared between the routers. In this case the packet
2050 decryption process is as with normal SILC packets. Hence, if the
2051 router is sending channel message to another router the Channel
2052 Message payload must have been decrypted and must be re-encrypted
2053 with the session key shared between the another router. In this
2054 case the packet encryption is as with any normal SILC packet.
2056 It must be noted that this is only when the channel messages are sent
2057 from router to another router. In all other cases the channel
2058 message encryption and decryption is as described above. This
2059 different processing of channel messages with router to router
2060 connection is because channel keys are cell specific. All cells has
2061 their own channel keys thus the channel message traveling from one
2062 cell to another must be protected as it would be any normal SILC
2067 2.5.3 Private Message Encryption And Decryption
2069 By default, private message in SILC are protected by session keys.
2070 In this case the private message encryption and decryption process is
2071 equivalent to normal packet encryption and decryption.
2073 However, private messages can be protected with private message key
2074 which causes the packet to be special packet. The procedure in this
2075 case is very much alike to channel packets. The actual private message
2076 is encrypted with the private message key and other parts of the
2077 packet is encrypted with the session key. See 2.7 Packet Padding
2078 Generation for more information about padding on special packets.
2080 The difference from channel message processing is that server or router
2081 en route never decrypts the actual private message, as it does not
2082 have the key to do that. Thus, when sending packets between router
2083 the processing is same as in any other case as well; the packet's header
2084 and padding is protected by the session key and the data area is not
2087 The true receiver of the private message, client, that is, is able
2088 to decrypt the private message as it shares the key with the sender
2093 2.6 Packet MAC Generation
2095 Data integrity of a packet is protected by including a message
2096 authentication code (MAC) at the end of the packet. The MAC is computed
2097 from shared secret MAC key, that is established by the SILC Key Exchange
2098 protocol, and from the original contents of the packet. The MAC is
2099 always computed before the packet is encrypted, although after it is
2100 compressed if compression is used.
2102 The MAC is computed from entire packet. Every bit of data in the packet,
2103 including SILC Packet Header is used in the MAC computing. This way
2104 the entire packet becomes authenticated.
2106 If the packet is special packet MAC is computed from the entire packet
2107 but part of the packet may be encrypted before the MAC is computed.
2108 This is case, for example, with channel messages where the message data
2109 is encrypted with key that server may not now. In this case the MAC
2110 has been computed from the encrypted data.
2112 See [SILC1] for defined and allowed MAC algorithms.
2116 2.7 Packet Padding Generation
2118 Padding is needed in the packet because the packet is encrypted. It
2119 must always be multiple by eight (8) or multiple by the size of the
2120 cipher's block size, which ever is larger. The padding is always
2123 For normal packets the padding is added after the SILC Packet Header
2124 and between the Data Payload area. The padding for normal packets
2125 are calculated as follows:
2128 padding length = 16 - ((packet length - 2) % 16)
2131 The 16 is the maximum padding allowed in SILC packet. Two (2) is
2132 subtracted from the true length of the packet because two (2) bytes
2133 is not encrypted in SILC Packet Header, see section 2.2 SILC Packet
2134 Header. Those two bytes that are not encrypted must not be calculated
2135 to the padding length.
2137 For special packets the padding calculation may be different as special
2138 packets may be encrypted differently. In these cases the encrypted
2139 data area must already be multiple by the block size thus in this case
2140 the padding is calculated only for SILC Packet Header, not for any
2141 other area of the packet. The same algorithm works in this case as
2142 well, except that the `packet length' is now the SILC Packet Header
2143 length. In this case, as well, two (2) is subtracted from the
2146 The padding must be random data, preferably, generated by
2147 cryptographically strong random number generator.
2151 2.8 Packet Compression
2153 SILC Packets may be compressed. In this case the data payload area
2154 is compressed and all other areas of the packet must remain as they
2155 are. After compression is performed for the data area, the length
2156 field of Packet Header must be set to the compressed length of the
2159 The compression must always be applied before encryption. When
2160 the packet is received and decrypted the data area must be decompressed.
2161 Note that the true sender of the packet must apply the compression and
2162 the true receiver of the packet must apply the decompression. Any
2163 server or router en route must not decompress the packet.
2169 The sender of the packet must assemble the SILC Packet Header with
2170 correct values. It must set the Source ID of the header as its own
2171 ID, unless it is forwarding the packet. It must also set the Destination
2172 ID of the header to the true destination. If the destination is client
2173 it will be Client ID, if it is server it will be Server ID and if it is
2174 channel it will be Channel ID.
2176 If the sender wants to compress the packet it must apply the
2177 compression now. Sender must also compute the padding as described
2178 in above sections. Then sender must compute the MAC of the packet.
2180 Then sender encrypts the packet as has been described in above
2181 sections according whether the packet is normal packet or special
2182 packet. The computed MAC must not be encrypted.
2186 2.10 Packet Reception
2188 On packet reception the receiver must check that all fields in the
2189 SILC Packet Header are valid sain. It must check the flags of the
2190 header and act accordingly. It must also check the MAC of the packet
2191 and if it is to be failed the packet must be discarded. Also if the
2192 header of the packet includes any bad fields the packet must be
2195 See above sections on the decryption process of the received packet.
2197 The receiver must also check that the ID's in the header are valid
2198 ID's. Unsupported ID types or malformed ID's must cause packet
2199 rejection. The padding on the reception is always ignored.
2201 The receiver must also check the packet type and start parsing the
2202 packet according to the type. However, note the above sections on
2203 special packet types and their parsing.
2209 Routers are the primary entities in the SILC network that takes care
2210 of packet routing. However, normal servers routes packets as well, for
2211 example, when they are routing channel message to the local clients.
2212 Routing is quite simple as every packet tells the true origin and the
2213 true destination of the packet.
2215 It is still recommended for routers that has several routing connections
2216 to create route cache for those destinations that has faster route than
2217 the router's primary route. This information is available for the router
2218 when other router connects to the router. The connecting party then
2219 sends all of its locally connected clients, server and channels. These
2220 informations helps to create the route cache. Also, when new channels
2221 are created to a cell its information is broadcasted to all routers
2222 in the network. Channel ID's are based on router's ID thus it is easy
2223 to create route cache based on these informations. If faster route for
2224 destination does not exist in router's route cache the packet must be
2225 routed to the primary route (default route).
2227 For server who receives a packet to be routed to its locally connected
2228 client the server must check whether the particular packet type is
2229 allowed to be routed to the client. Not all packets may be sent by
2230 some odd entity to client that is indirectly connected to the sender.
2231 See section 2.3 SILC Packet Types and paragraph about indirectly connected
2232 entities and sending packets to them. The section mentions the packets
2233 that may be sent to indirectly connected entities. It is clear that some
2234 server cannot send, for example, disconnect packet to client that is not
2235 directly connected to the server.
2239 2.12 Packet Forwarding
2241 Currently SILC command packets may be forwarded from one entity to another.
2242 Any other packet currently cannot be forwarded but support for more packet
2243 types may be added if needed. Forwarding is usually used by server to
2244 forward some command request coming from client to the router as the server
2245 may be incapable to handle the request. Forwarding may be only one hop
2246 long; the receiver of the packet with Forwarded flag set in the SILC
2247 Packet header must not forward the packet any further.
2249 The normal scenario is that client sends JOIN command to the server which
2250 is not able to create the channel as there are no local clients on the
2251 channel. Channels are created always by the router of the cell thus the
2252 packet must be forwarded to the router. The server forwards the original
2253 packet coming from client to the router after it has set the Forwarded
2254 flag to the SILC Packet header.
2256 Router receiving the packet knows that the packet has to be processed
2257 specially by checking the flags and the Forwarded flag in the SILC Packet
2258 header. After router has joined the client to the channel (and perhaps
2259 created a new channel) it sends normal command reply packet to the
2260 client. However, as the router doesn't have direct connection to the
2261 client the packet is sent through the server. Server detects that
2262 the command reply packet is destined to the client and sends it to
2267 2.13 Packet Broadcasting
2269 SILC packets may be broadcasted in SILC network. However, only router
2270 server may send or receive broadcast packets. Client and normal server
2271 must not send broadcast packets and they must ignore broadcast packets
2272 if they receive them. Broadcast packets are sent by setting Broadcast
2273 flag to the SILC packet header.
2275 Broadcasting packets means that the packet is sent to all routers in
2276 the SILC network, except to the router that sent the packet. The router
2277 receiving broadcast packet must send the packet to its primary route.
2278 The fact that SILC routers may have several router connections may
2279 cause problems, such as race conditions inside the SILC network, if
2280 care is not taken when broadcasting packets. Router must not send
2281 the broadcast packet to any other route except to its primary route.
2283 If the primary route of the router is the original sender of the packet
2284 the packet must not be sent to the primary route. This may happen
2285 if router has several router connections and some other router uses
2286 the router as its primary route.
2288 Routers use broadcast packets to broadcast for example information
2289 about newly registered clients, servers, channels etc. so that all the
2290 routers may keep these informations up to date.
2294 2.14 Packet Tunneling
2296 Tunneling is a feature that is available in SILC protocol. Tunneling
2297 means that extra SILC Packet Header is applied to the original packet
2298 and thus hiding the original packet entirely. There can be some
2299 interesting applications using tunneling, such as, using ID's based on
2300 private network IP addresses inside in the tunneled packet. This can
2301 open many interesting features relating to connecting to private network
2302 from the Internet with SILC and many more. However, this feature is
2303 optional currently in SILC as there does not exist thorough analysis of
2304 this feature. It is with out a doubt that there will be many more
2305 applications that has not yet been discovered. Thus, it is left
2306 to Internet Community to investigate the use of tunneling in SILC
2307 protocol. This document is updated according those investigations
2308 and additional documents on the issue may be written.
2312 3 Security Considerations
2314 Security is central to the design of this protocol, and these security
2315 considerations permeate the specification.
2321 [SILC1] Riikonen, P., "Secure Internet Live Conferencing (SILC),
2322 Protocol Specification", Internet Draft, June 2000.
2324 [SILC3] Riikonen, P., "SILC Key Exchange and Authentication
2325 Protocols", Internet Draft, June 2000.
2327 [IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
2330 [SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
2333 [PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
2336 [SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
2339 [PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
2340 Infrastructure, Certificate and CRL Profile", RFC 2459,
2343 [Schneier] Schneier, B., "Applied Cryptography Second Edition",
2344 John Wiley & Sons, New York, NY, 1996.
2346 [Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
2349 [OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
2350 RFC 2412, November 1998.
2352 [ISAKMP] Maughan D., et al, "Internet Security Association and
2353 Key Management Protocol (ISAKMP)", RFC 2408, November
2356 [IKE] Harkins D., and Carrel D., "The Internet Key Exhange
2357 (IKE)", RFC 2409, November 1998.
2359 [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
2360 Authentication", RFC 2104, February 1997.
2372 EMail: priikone@poseidon.pspt.fi
2374 This Internet-Draft expires 28 Jan 2001
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