8 .ds RF FORMFEED[Page %]
17 Network Working Group P. Riikonen
19 draft-riikonen-silc-pp-01.txt 6 October 2000
26 <draft-riikonen-silc-pp-01.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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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 Generic payloads .................................... 16
81 2.3.2.1 ID Payload .................................. 16
82 2.3.2.2 Argument Payload ............................ 16
83 2.3.3 Disconnect Payload .................................. 17
84 2.3.4 Success Payload ..................................... 18
85 2.3.5 Failure Payload ..................................... 18
86 2.3.6 Reject Payload ...................................... 19
87 2.3.7 Notify Payload ...................................... 20
88 2.3.8 Error Payload ....................................... 21
89 2.3.9 Channel Message Payload ............................. 22
90 2.3.10 Channel Key Payload ................................ 24
91 2.3.11 Private Message Payload ............................ 26
92 2.3.12 Private Message Key Payload ........................ 27
93 2.3.13 Command Payload .................................... 28
94 2.3.14 Command Reply Payload .............................. 29
95 2.3.15 Connection Auth Request Payload .................... 29
96 2.3.16 New ID Payload ..................................... 30
97 2.3.17 New Client Payload ................................. 31
98 2.3.18 New Server Payload ................................. 32
99 2.3.19 New Channel Payload ................................ 33
100 2.3.20 Key Agreement Payload .............................. XXX
101 2.4 SILC ID Types ............................................. 39
102 2.5 Packet Encryption And Decryption .......................... 39
103 2.5.1 Normal Packet Encryption And Decryption ............. 39
104 2.5.2 Channel Message Encryption And Decryption ........... 40
105 2.5.3 Private Message Encryption And Decryption ........... 41
106 2.6 Packet MAC Generation ..................................... 41
107 2.7 Packet Padding Generation ................................. 42
108 2.8 Packet Compression ........................................ 42
109 2.9 Packet Sending ............................................ 43
110 2.10 Packet Reception ......................................... 43
111 2.11 Packet Routing ........................................... 44
112 2.12 Packet Broadcasting ...................................... 45
113 2.13 Packet Tunneling ......................................... 45
114 3 Security Considerations ....................................... 46
115 4 References .................................................... 46
116 5 Author's Address .............................................. 47
122 Figure 1: Typical SILC Packet
123 Figure 2: SILC Packet Header
125 Figure 4: Argument Payload
126 Figure 5: Disconnect Payload
127 Figure 6: Success Payload
128 Figure 7: Failure Payload
129 Figure 8: Reject Payload
130 Figure 9: Notify Payload
131 Figure 10: Error Payload
132 Figure 11: Channel Message Payload
133 Figure 12: Channel Key Payload
134 Figure 13: Private Message Payload
135 Figure 14: Private Message Key Payload
136 Figure 15: Command Payload
137 Figure 16: Connection Auth Request Payload
138 Figure 17: New Client Payload
139 Figure 18: New Server Payload
140 Figure 19: New Channel Payload
146 This document describes a Packet Protocol used in the Secure Internet
147 Live Conferencing (SILC) protocol specified in the Secure Internet Live
148 Conferencing, Protocol Specification Internet Draft [SILC1]. This
149 protocol describes the packet types and packet payloads which defines
150 the contents of the packets. The protocol provides secure binary packet
151 protocol that assures that the contents of the packets are secured and
154 The basis of SILC protocol relies in the SILC packets and it is with
155 out a doubt the most important part of the protocol. It is also probably
156 the most complicated part of the protocol. Packets are used all the
157 time in the SILC network to send messages, commands and other information.
158 All packets in SILC network are always encrypted and their integrity
159 is assured by computed MACs. The protocol defines several packet types
160 and packet payloads. Each packet type usually has a specific packet
161 payload that actually defines the contents of the packet. Each packet
162 also includes a default SILC Packet Header that provides sufficient
163 information about the origin of the packet and destination of the
168 2 SILC Packet Protocol
173 SILC packets deliver messages from sender to receiver securely by
174 encrypting important fields of the packet. The packet consists of
175 default SILC Packet Header, Padding, Packet Payload data, and, packet
178 The following diagram illustrates typical SILC packet.
183 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
184 | n bytes | 1 - n bytes | n bytes | n bytes
185 | SILC Header | Padding | Data Payload | MAC
186 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
190 Figure 1: Typical SILC Packet
193 SILC Header is always the first part of the packet and its purpose
194 is to provide information about the packet. It provides for example
195 the packet type, origin of the packet and the destination of the packet.
196 The header is variable in length and first two (2) bytes of the
197 header (thus first two bytes of the packet) are not encrypted. The
198 first two (2) bytes are the length of the packet which is not encrypted.
199 See The following section for description of SILC Packet header. Packets
200 without SILC header or with malformed SILC header must be dropped.
202 Padding follows the packet header. The purpose of the padding is to
203 make the packet multiple by eight (8) or by the block size of the
204 cipher used in the encryption, which ever is larger. The maximum
205 length of padding is currently 16 bytes. The padding is always
208 Data payload area follows padding and it is the actual data of the
209 packet. The packet data is the packet payloads defined in this
210 protocol. The data payload area is always encrypted.
212 The last part of SILC packet is the packet MAC that assures the
213 integrity of the packet. The MAC is always computed from the packet
214 before the encryption is applied to the packet. If compression is used
215 in the packet the MAC is computed after the compression has been
216 applied. The compression, on the other hand, is always applied before
219 All fields in all packet payloads are always in MSB (most significant
224 2.2 SILC Packet Header
226 The default SILC packet header is applied to all SILC packets and it is
227 variable in length. The purpose of SILC Packet header is to provide
228 detailed information about the packet. The receiver of the packet uses
229 the packet header to parse the packet and gain other relevant parameters
232 The following diagram represents the default SILC header format.
233 (*) indicates that this field is never encrypted. Other fields are
240 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
241 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
242 | Payload Length * | Flags | Packet Type |
243 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
244 | Source ID Length | Destination ID Length |
245 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
251 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
261 Figure 2: SILC Packet Header
265 o Payload Length (2 bytes) - Is the length of the packet
266 not including the padding of the packet. This field must
267 not be encrypted but must always be authenticated.
269 o Flags (1 byte) - Indicates flags to be used in packet
270 processing. Several flags may be set by ORing the flags
273 The following flags are reserved for this field:
278 In this case the field is ignored.
281 Private Message Key 0x01
283 Indicates that the packet must include private
284 message that is encrypted using private key set by
285 client. Servers does not know anything about this
286 key and this causes that the private message is
287 not handled by the server at all, it is just
288 passed along. See section 2.5.3 Private Message
289 Encryption And Decryption for more information.
294 Indicates that the packet consists of list of
295 packet payloads indicated by the Packet Type field.
296 The payloads are added one after the other. Note that
297 there are packet types that must not be used as
298 list. Parsing of list packet is done by calculating
299 the length of each payload and parsing them one by
305 Marks the packet to be broadcasted. Client cannot
306 send broadcast packet and normal server cannot send
307 broadcast packet. Only router server may send broadcast
308 packet. The router receiving of packet with this flag
309 set must send (broadcast) the packet to its primary
310 route. If router has several router connections the
311 packet may be sent only to the primary route. See
312 section 2.13 Packet Broadcasting for description of
318 Marks that the packet is tunneled. Tunneling means
319 that extra SILC Packet Header has been applied to the
320 original packet. The outer header has this flag
321 set. See section 2.14 Packet Tunneling for more
327 o Packet Type (1 byte) - Is the type of the packet. Receiver
328 uses this field to parse the packet. See section 2.3
329 SILC Packets for list of defined packet types.
331 o Source ID Length (2 bytes) - Indicates the length of the
332 Source ID field in the header, not including this or any
335 o Destination ID Length (2 bytes) - Indicates the length of the
336 Destination ID field in the header, not including this or
339 o Src ID Type (1 byte) - Indicates the type of ID in the
340 Source ID field. See section 2.4 SILC ID Types for
343 o Source ID (variable length) - The actual source ID that
344 indicates who is the original sender of the packet.
346 o Dst ID Type (1 byte) - Indicates the type of ID in the
347 Destination ID field. See section 2.4 SILC ID Types for
350 o Destination ID (variable length) - The actual source ID that
351 indicates who is the end receiver of the packet.
355 2.3 SILC Packet Types
357 SILC packet types defines the contents of the packet and it is used by
358 the receiver to parse the packet. The packet type is 8 bits, as a one
359 byte, in length. The range for the packet types are from 0 - 255,
360 where 0 is never sent and 255 is currently reserved for future
361 extensions and must not be defined to any other purpose. Every SILC
362 specification compliant implementation should support all of these packet
365 The below list of the SILC Packet types includes reference to the packet
366 payload as well. Packet payloads are the actual packet, that is, the data
367 that the packet consists of. Each packet type defines packet payload
368 which usually may only be sent with the specific packet type.
370 Most of the packets are packets that must be destined directly to entity
371 that is connected to the sender. It is not allowed, for example, for
372 router to send disconnect packet to client that is not directly connected
373 to the router. However, there are some special packet types that may
374 be destined to some entity that the sender has not direct connection
375 with. These packets are for example private message packets, channel
376 message packets, command packets and some other packets that may be
377 broadcasted in the SILC network. If the packet is allowed to be sent to
378 indirectly connected entity it is mentioned separately in the packet
379 description (unless it is obvious as in private and channel message
380 packets). Other packets must not be sent or accepted, if sent, to
381 indirectly connected entities.
383 List of SILC Packet types are defined as follows.
388 This type is reserved and it is never sent.
391 1 SILC_PACKET_DISCONNECT
393 This packet is sent to disconnect the remote end. Reason of
394 the disconnection is sent inside the packet payload. Client
395 usually does not send this packet.
397 This packet must not be sent as list and the List flag must
400 Payload of the packet: See section 2.3.3 Disconnect Payload
403 2 SILC_PACKET_SUCCESS
405 This packet is sent upon successful execution of some protocol.
406 The status of the success is sent in the packet.
408 This packet must not be sent as list and the List flag must
411 Payload of the packet: See section 2.3.4 Success Payload
414 3 SILC_PACKET_FAILURE
416 This packet is sent upon failure of some protocol. The status
417 of the failure is sent in the packet.
419 This packet must not be sent as list and the List flag must
422 Payload of the packet: See section 2.3.5 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 This packet must not be sent as list and the List flag must
433 Payload of the packet: See section 2.3.6 Reject Payload
438 This packet is used to send notify message, usually from
439 server to client, although it may be sent from server to another
440 server as well. Client never sends this packet. Server may
441 send this packet to channel as well when the packet is
442 distributed to all clients on the channel.
444 Payload of the packet: See section 2.3.7 Notify Payload.
449 This packet is sent when an error occurs. Server may
450 send this packet. Client never sends this packet. The
451 client may entirely ignore the packet, however, server is
452 most likely to take action anyway. This packet may be sent
453 to entity that is indirectly connected to the sender.
455 This packet must not be sent as list and the List flag must
458 Payload of the packet: See section 2.3.8 Error Payload.
461 7 SILC_PACKET_CHANNEL_MESSAGE
463 This packet is used to send messages to channels. The packet
464 includes Channel ID of the channel and the actual message to
465 the channel. Messages sent to the channel are always protected
466 by channel specific keys. Channel Keys are distributed by
467 SILC_PACKET_CHANNEL_KEY packet.
469 This packet must not be sent as list and the List flag must
472 Payload of the packet: See section 2.3.9 Channel Message
476 8 SILC_PACKET_CHANNEL_KEY
478 This packet is used to distribute new key for particular
479 channel. Each channel has their own independent keys that
480 is used to protect the traffic on the channel. Only server
481 may send this packet. This packet may be sent to entity
482 that is indirectly connected to the sender.
484 This packet must not be sent as list and the List flag must
487 Payload of the packet: See section 2.3.10 Channel Key Payload
490 9 SILC_PACKET_PRIVATE_MESSAGE
492 This packet is used to send private messages from client
493 to another client. By default, private messages are protected
494 by session keys established by normal key exchange protocol.
495 However, it is possible to use specific key to protect private
496 messages. SILC_PACKET_PRIVATE_MESSAGE_KEY packet is used to
497 agree the key with the remote client. Pre-shared key may be
498 used as well if both of the client knows it, however, it needs
499 to be agreed outside SILC. See more of this in [SILC1].
501 This packet must not be sent as list and the List flag must
504 Payload of the packet: See section 2.3.11 Private Message
508 10 SILC_PACKET_PRIVATE_MESSAGE_KEY
510 This packet is used to agree about a key to be used to protect
511 the private messages between two clients. If this is not sent
512 the normal session key is used to protect the private messages
513 inside SILC network. Agreeing to use specific key to protect
514 private messages adds security, as no server between the two
515 clients will be able to decrypt the private message. However,
516 servers inside SILC network are considered to be trusted, thus
517 using normal session key to protect private messages does not
518 degree security. Whether to agree to use specific keys by
519 default or to use normal session keys by default, is
520 implementation specific issue. See more of this in [SILC1].
522 This packet must not be sent as list and the List flag must
525 Payload of the packet: See section 2.3.12 Private Message
529 11 SILC_PACKET_COMMAND
531 This packet is used to send commands from client to server.
532 Server may send this packet to other servers as well. All
533 commands are listed in their own section SILC Command Types
534 in [SILC1]. The contents of this packet is command specific.
535 This packet may be sent to entity that is indirectly connected
538 This packet must not be sent as list and the List flag must
541 Payload of the packet: See section 2.3.13 Command Payload
544 12 SILC_PACKET_COMMAND_REPLY
546 This packet is send as reply to the SILC_PACKET_COMMAND packet.
547 The contents of this packet is command specific. This packet
548 maybe sent to entity that is indirectly connected to the sender.
550 This packet must not be sent as list and the List flag must
553 Payload of the packet: See section 2.3.14 Command Reply
554 Payload and section 2.3.13 Command
558 13 SILC_PACKET_KEY_EXCHANGE
560 This packet is used to start SILC Key Exchange Protocol,
561 described in detail in [SILC3].
563 This packet must not be sent as list and the List flag must
566 Payload of the packet: Payload of this packet is described
567 in the section SILC Key Exchange
568 Protocol and its sub sections in
572 14 SILC_PACKET_KEY_EXCHANGE_1
574 This packet is used as part of the SILC Key Exchange Protocol.
576 This packet must not be sent as list and the List flag must
579 Payload of the packet: Payload of this packet is described
580 in the section SILC Key Exchange
581 Protocol and its sub sections in
585 15 SILC_PACKET_KEY_EXCHANGE_2
587 This packet is used as part of the SILC Key Exchange Protocol.
589 This packet must not be sent as list and the List flag must
592 Payload of the packet: Payload of this packet is described
593 in the section SILC Key Exchange
594 Protocol and its sub sections in
598 16 SILC_PACKET_CONNECTION_AUTH_REQUEST
600 This packet is used to request the authentication method to
601 be used in the SILC Connection Authentication Protocol. If
602 initiator of the protocol does not know the mandatory
603 authentication method this packet is used to determine it.
605 The party receiving this payload must respond with the same
606 packet including the mandatory authentication method.
608 This packet must not be sent as list and the List flag must
611 Payload of the packet: See section 2.3.15 Connection Auth
615 17 SILC_PACKET_CONNECTION_AUTH
617 This packet is used to start and perform the SILC Connection
618 Authentication Protocol. This protocol is used to authenticate
619 the connecting party. The protocol is described in detail in
622 This packet must not be sent as list and the List flag must
625 Payload of the packet: Payload of this packet is described
626 in the section SILC Authentication
627 Protocol and it sub sections in [SILC].
630 18 SILC_PACKET_NEW_ID
632 This packet is used to distribute new ID's from server to
633 router and from router to all routers in the SILC network.
634 This is used when for example new client is registered to
635 SILC network. The newly created ID's of these operations are
636 distributed by this packet. Only server may send this packet,
637 however, client must be able to receive this packet.
639 Payload of the packet: See section 2.3.16 New ID Payload
642 19 SILC_PACKET_NEW_CLIENT
644 This packet is used by client to register itself to the
645 SILC network. This is sent after key exchange and
646 authentication protocols has been completed. Client sends
647 various information about itself in this packet.
649 This packet must not be sent as list and the List flag must
652 Payload of the packet: See section 2.3.17 New Client Payload
655 20 SILC_PACKET_NEW_SERVER
657 This packet is used by server to register itself to the
658 SILC network. This is sent after key exchange and
659 authentication protocols has been completed. Server sends
660 this to the router it connected to, or, if router was
661 connecting, to the connected router. Server sends
662 its Server ID and other information in this packet.
663 Client must not send or receive this packet.
665 This packet must not be sent as list and the List flag must
668 Payload of the packet: See section 2.3.18 New Server Payload
671 21 SILC_PACKET_NEW_CHANNEL
673 This packet is used to notify routers about newly created
674 channel. Channels are always created by the router and it must
675 notify other routers about the created channel. Router sends
676 this packet to its primary route. Client must not send this
677 packet. This packet maybe sent to entity that is indirectly
678 connected to the sender.
680 Payload of the packet: See section 2.3.19 New Channel Payload
685 This packet is used to indicate that re-key must be performed
686 for session keys. See section Session Key Regeneration in
687 [SILC1] for more information. This packet does not have
690 This packet must not be sent as list and the List flag must
694 23 SILC_PACKET_REKEY_DONE
696 This packet is used to indicate that re-key is performed and
697 new keys must be used hereafter. This is sent only if re-key
698 was done without PFS option. If PFS is set, this is not sent
699 as SILC Key Exchange protocol is executed. This packet does
702 This packet must not be sent as list and the List flag must
706 24 SILC_PACKET_HEARTBEAT
708 This packet is used by clients, servers and routers to keep the
709 connection alive. It is recommended that all servers implement
710 keepalive actions and perform it to both direction in a link.
711 This packet does not have a payload.
713 This packet must not be sent as list and the List flag must
717 25 SILC_PACKET_KEY_AGREEMENT
719 This packet is used by clients to request key negotiation
720 between another client in the SILC network. If the negotiation
721 is started it is performed using the SKE protocol. The result of
722 the negotiation, the secret key material, can be used for
723 example as private message key. The server and router must not
726 Payload of the packet: See section 2.3.20 Key Agreement Payload
731 Currently undefined commands.
736 These packet types are reserved for private use and they will not
737 be defined by this document.
742 This type is reserved for future extensions and currently it
748 2.3.1 SILC Packet Payloads
750 All payloads resides in the main data area of the SILC packet. However
751 all payloads must be at the start of the data area after the default
752 SILC packet header and padding. All fields in the packet payload are
753 always encrypted, as, they reside in the data area of the packet which
756 Payloads described in this section are common payloads that must be
757 accepted anytime during SILC session. Most of the payloads may only
758 be sent with specific packet type which is defined in the description
761 There are a lot of other payloads in the SILC as well. However, they
762 are not common in the sense that they could be sent at any time.
763 These payloads are not described in this section. These are payloads
764 such as SILC Key Exchange payloads and so on. These are described
765 in [SILC1] and [SILC3].
769 2.3.2 Generic payloads
771 This section describes generic payloads that are not associated to any
772 specific packet type. They can be used for example inside some other
779 This payload can be used to send an ID. ID's are variable length thus
780 this payload provides a way to send variable length ID's.
782 The following diagram represents the ID Payload.
787 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
788 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
789 | ID Type | ID Length |
790 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
794 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
802 o ID Type (2 bytes) - Indicates the type of the ID. See
803 section 2.4 SILC ID Types for list of defined ID types.
805 o ID Length (2 bytes) - Length of the ID Data area not
806 including the length of any other fields in the payload.
808 o ID Data (variable length) - The actual ID data.
813 2.3.2.2 Argument Payload
815 Argument Payload is used to set arguments for any packet payload that
816 needs and supports arguments, such as commands. Number of arguments
817 associated with a packet must be indicated by the packet payload who
818 needs the arguments. Argument Payloads must always reside right after
819 the packet payload needing the arguments. Incorrect amount of argument
820 payloads must cause rejection of the packet. The following diagram represents
821 the Argument Payload.
827 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
828 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
829 | Payload Length | Argument Type | |
830 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
834 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
838 Figure 4: Argument Payload
842 o Payload Length (2 bytes) - Length of the argument payload data
843 area not including the length of any other fields in the
846 o Argument Type (1 byte) - Indicates the type of the argument.
847 Every argument may have a specific type that must be defined
848 by the packet payload needing the argument. For example
849 every command specify a number for each argument that maybe
850 associated with the command. By using this number the receiver
851 of the packet knows what type of argument this is. If there is
852 no specific argument type this field is set to zero (0).
854 o Argument Data (variable length) - Argument data.
859 2.3.3 Disconnect Payload
861 Disconnect payload is sent upon disconnection. The payload is simple;
862 reason of disconnection is sent to the disconnected party.
864 The payload may only be sent with SILC_PACKET_DISCONNECT packet. It
865 must not be sent in any other packet type. The following diagram represents
866 the Disconnect Payload.
877 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
878 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
880 ~ Disconnect Message ~
882 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
886 Figure 5: Disconnect Payload
892 o Disconnect Message (variable length) - Human readable
893 reason of the disconnection.
898 2.3.4 Success Payload
900 Success payload is sent when some protocol execution is successfully
901 completed. The payload is simple; indication of the success is sent.
902 This maybe any data, including binary or human readable data.
907 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
908 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
910 ~ Success Indication ~
912 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
916 Figure 6: Success Payload
920 o Success Indication (variable length) - Indication of
921 the success. This maybe for example some flag that
922 indicates the protocol and the success status or human
923 readable success message. The true length of this
924 payload is available by calculating it from the SILC
930 2.3.5 Failure Payload
932 This is opposite of Success Payload. Indication of failure of
933 some protocol is sent in the payload.
939 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
940 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
942 ~ Failure Indication ~
944 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
948 Figure 7: Failure Payload
952 o Failure Indication (variable length) - Indication of
953 the failure. This maybe for example some flag that
954 indicates the protocol and the failure status or human
955 readable failure message. The true length of this
956 payload is available by calculating it from the SILC
964 This payload is sent when some protocol is rejected to be executed.
965 Other operations may send this as well that was rejected. The
966 indication of the rejection is sent in the payload. The indication
967 may be binary or human readable data.
973 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
974 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
976 ~ Reject Indication ~
978 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
982 Figure 8: Reject Payload
986 o Reject Indication (variable length) - Indication of
987 the rejection. This maybe for example some flag that
988 indicates the protocol and the rejection status or human
989 readable rejection message. The true length of this
990 payload is available by calculating it from the SILC
1001 Notify payload is used to send notify messages. The payload is usually
1002 sent from server to client, however, server may send it to another
1003 server as well. This payload may also be sent to a channel. Client must
1004 not send this payload. The receiver of this payload may totally ignore the
1005 contents of the payload, however, notify message should be audited.
1007 The payload may only be sent with SILC_PACKET_NOTIFY packet. It must
1008 not be sent in any other packet type. The following diagram represents the
1014 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
1015 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1016 | Notify Type | Payload Length |
1017 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1023 Figure 9: Notify Payload
1027 o Notify Type (2 bytes) - Indicates the type of the notify
1030 o Payload Length (2 bytes) - Length of the entire Notify Payload
1031 including any associated Argument Payloads.
1033 o Argument Nums (2 bytes) - Indicates the number of Argument
1034 Payloads associated to this payload. Notify types may define
1035 arguments to be send along the notify message.
1038 The following list of currently defined notify types. The format for notify
1039 arguments is same as in SILC commands described in [SILC1]. Also, all
1040 ID's sent in arguments are sent inside ID Payload.
1043 0 SILC_NOTIFY_TYPE_NONE
1045 If no specific notify type apply for the notify message this type
1049 Arguments: (1) <message>
1051 The <message> is implementation specific free text string. Receiver
1052 may ignore this message.
1055 1 SILC_NOTIFY_TYPE_INVITE
1057 Sent when receiver has been invited to a channel. This type must be
1058 sent directly to the invited client.
1061 Arguments: (1) <Client ID> (2) <Channel ID>
1063 The <Client ID> is the client who invites the receiver of this type
1064 to channel indicated by <Channel ID>.
1067 2 SILC_NOTIFY_TYPE_JOIN
1069 Sent when client has joined to a channel. The server must distribute
1070 this type only to the local clients on the channel and then send
1071 it to its primary router. The router or server receiving the packet
1072 distributes this type to the local clients on the channel and
1073 broadcast it to the network.
1076 Arguments: (1) <Client ID> (2) <Channel ID>
1078 The <Client ID> is the client that joined to the channel indicated
1079 by the <Channel ID>.
1082 3 SILC_NOTIFY_TYPE_LEAVE
1084 Sent when client has left a channel. The server must distribute
1085 this type only to the local clients on the channel and then send
1086 it to its primary router. The router or server receiving the packet
1087 distributes this type to the local clients on the channel and
1088 broadcast it to the network.
1091 Arguments: (1) <Client ID>
1093 The <Client ID> is the client who left the channel.
1096 4 SILC_NOTIFY_TYPE_SIGNOFF
1098 Sent when client signoffs from SILC network. The server must
1099 distribute this type only to the local clients on the channel and
1100 then send it to its primary router. The router or server receiving
1101 the packet distributes this type to the local clients on the channel
1102 and broadcast it to the network.
1105 Arguments: (1) <Client ID> (2) <message>
1107 The <Client ID> is the client who left SILC network. The <message>
1108 is free text string indicating the reason of signoff.
1111 5 SILC_NOTIFY_TYPE_TOPIC_SET
1113 Sent when topic is set/changed on a channel. This type must be sent
1114 only to the clients who is joined on the channel whose topic was
1118 Arguments: (1) <Client ID> (2) <topic>
1120 The <Client ID> is the client who set or changed the <topic>.
1123 6 SILC_NOTIFY_TYPE_NICK_CHANGE
1125 Sent when client changes nick on a channel. The server must
1126 distribute this type only to the local clients on the channel and
1127 then send it to its primary router. The router or server receiving
1128 the packet distributes this type to the local clients on the channel
1129 and broadcast it to the network.
1132 Arguments: (1) <Old Client ID> (2) <New Client ID>
1134 The <Old Client ID> is the old ID of the client who changed the
1135 nickname. The <New Client ID> is the new ID generated by the change
1139 7 SILC_NOTIFY_TYPE_CMODE_CHANGE
1141 Sent when channel mode has changed. This type must be sent only to
1142 the clients who is joined on the channel whose mode was changed.
1145 Arguments: (1) <Client ID> (2) <mode mask>
1147 The <Client ID> is the client who changed the mode. The <mode mask>
1148 is the new mode mask of the channel.
1151 8 SILC_NOTIFY_TYPE_CUMODE_CHANGE
1153 Sent when user mode on channel has changed. This type must be sent
1154 only to the clients who is joined on the channel where the target
1158 Arguments: (1) <Client ID> (2) <mode mask>
1159 (3) <Target Client ID>
1161 The <Client ID> is the client who changed the mode. The <mode mask>
1162 is the new mode mask of the channel. The <Target Client ID> is the
1163 client which mode was changed.
1166 9 SILC_NOTIFY_TYPE_MOTD
1168 Sent when Message of the Day (motd) is sent to client.
1171 Arguments: (1) <motd>
1173 The <motd> is the Message of the Day.
1176 10 SILC_NOTIFY_TYPE_CHANNEL_CHANGE
1178 Sent when channel's ID has changed for a reason or another. This
1179 is sent by noral server to the client. Client must change the
1180 old Channel ID to the new one. This type must be sent only to the
1181 clients who is joined on the channel.
1184 Arguments: (1) <Old Channel ID> (2) <New Channel ID>
1186 The <Old Channel ID> is the channel's old ID and the <New Channel ID>
1187 is the new one that must replace the old one.
1190 11 SILC_NOTIFY_TYPE_SERVER_SIGNOFF
1192 Sent when server quits SILC network. Those clients from this server
1193 that are on channels must be removed from the channel.
1196 Arguments: (1) <Server ID>
1198 The <Server ID> is the server's ID.
1201 12 SILC_NOTIFY_TYPE_KICKED
1203 Sent when a client has been kicked from a channel. This is sent
1204 also to the client who was kicked from the channel. The client
1205 who was kicked from the channel must be removed from the channel.
1206 This notify type is always destined to the channel. The router or
1207 server receiving the packet distributes this type to the local
1208 clients on the channel and broadcast it to the network.
1211 Arguments: (1) <Client ID> (2) [<comment>]
1213 The <Client ID> is the client who was kicked from the channel.
1214 The kicker may have set the <comment> to indicate the reason for
1219 Notify types starting from 16384 are reserved for private notify
1226 Error payload is sent upon error. Error may occur in various
1227 conditions when server sends this packet. Client may not send this
1228 payload but must be able to accept it. However, client may
1229 totally ignore the contents of the packet as server is going to
1230 take action on the error anyway. However, it is recommended
1231 that the client takes error packet seriously.
1237 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
1238 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1242 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1246 Figure 10: Error Payload
1250 o Error Message (variable length) - Human readable error
1256 2.3.9 Channel Message Payload
1258 Channel messages are the most common messages sent in the SILC.
1259 Channel Message Payload is used to send message to channels. These
1260 messages can only be sent if client has joined to some channel.
1261 Even though this packet is the most common in SILC it is still
1262 special packet. Some special handling on sending and reception
1263 of channel message is required.
1265 Padding must be applied into this payload since the payload is
1266 encrypted separately from other parts of the packet with the
1267 channel specific key. Hence the requirement of the padding.
1268 The padding should be random data. The packet must be made
1269 multiple by eight (8) or by the block size of the cipher, which
1272 The SILC header in this packet is encrypted with the session key
1273 of the next receiver of the packet. Nothing else is encrypted
1274 with that key. Thus, the actual packet and padding to be
1275 encrypted with the session key is SILC Header plus padding to it
1276 to make it multiple by eight (8) or multiple by the block size
1277 of the cipher, which ever is larger.
1279 Receiver of the the channel message packet is able to determine
1280 the channel the message is destined to by checking the destination
1281 ID from the SILC Packet header which tells the destination channel.
1282 The original sender of the packet is also determined by checking
1283 the source ID from the header which tells the client who sent
1286 The payload may only be sent with SILC_PACKET_CHANNEL_MESSAGE packet.
1287 It must not be sent in any other packet type. The following diagram
1288 represents the Channel Message Payload.
1290 (*) indicates that the field is not encrypted.
1296 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
1297 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1298 | Message Length | |
1299 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1303 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1304 | Padding Length | |
1305 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1309 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1313 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1315 ~ Initial Vector * ~
1317 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1321 Figure 11: Channel Message Payload
1325 o Message Length (2 bytes) - Indicates the length of the
1326 the Message Data field in the payload, not including any
1329 o Message Data (variable length) - The actual message to
1332 o Padding Length (2 bytes) - Indicates the length of the
1333 Padding field in the payload, not including any other
1336 o Padding (variable length) - The padding that must be
1337 applied because this payload is encrypted separately from
1338 other parts of the packet.
1340 o MAC (variable legnth) - The MAC computed from the
1341 Message Length, Message Data, Padding Length and Padding
1342 fields. This protects the integrity of the plaintext
1343 channel message. The receiver can verify from the MAC
1344 whether the message decrypted correctly. Also, if more than
1345 one private key has been set for the channel, the receiver
1346 can verify which of the keys decrypted the message
1347 correctly. Note that, this field is encrypted and must
1348 be added to the padding calculation.
1350 o Initial Vector (variable length) - The initial vector
1351 that has been used in packet encryption. It needs to be
1352 used in the packet decryption as well. What this field
1353 includes is implementation issue. However, it is
1354 recommended that it would be random data or, perhaps,
1355 a timestamp. It is not recommended to use zero (0) as
1356 initial vector. This field is not encrypted. This field
1357 is not included into the padding calculation. Length
1358 of this field equals the cipher's block size. This field
1359 is, however, authenticated.
1364 2.3.10 Channel Key Payload
1366 All traffic in channels are protected by channel specific keys.
1367 Channel Key Payload is used to distribute channel keys to all
1368 clients on the particular channel. Channel keys are sent when
1369 the channel is created, when new user joins to the channel and
1370 whenever a user has left a channel. Server creates the new
1371 channel key and distributes it to the clients by encrypting this
1372 payload with the session key shared between the server and
1373 the client. After that, client starts using the key received
1374 in this payload to protect the traffic on the channel.
1376 The client who is joining to the channel receives its key in the
1377 SILC_COMMAND_JOIN command reply message thus it is not necessary to
1378 send this payload to the entity who sent the SILC_COMMAND_JOIN command.
1380 Channel keys are cell specific thus every router in cell have
1381 to create a channel key and distribute it if any client in the
1382 cell has joined to a channel. Channel traffic between cell's
1383 are not encrypted using channel keys, they are encrypted using
1384 normal session keys between two routers. Inside a cell, all
1385 channel traffic is encrypted with the specified channel key.
1386 Channel key should expire periodically, say, in one hour, in
1387 which case new channel key is created and distributed.
1389 The payload may only be sent with SILC_PACKET_CHANNEL_KEY packet.
1390 It must not be sent in any other packet type. The following diagram
1391 represents the Channel Key Payload.
1408 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
1409 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1410 | Channel ID Length | |
1411 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1415 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1416 | Cipher Name Length | |
1417 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1421 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1422 | Channel Key Length | |
1423 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1427 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1431 Figure 12: Channel Key Payload
1436 o Channel ID Length (2 bytes) - Indicates the length of the
1437 Channel ID field in the payload, not including any other
1440 o Channel ID (variable length) - The Channel ID of the
1441 channel this key is meant for.
1443 o Cipher Name Length (2 bytes) - Indicates the length of the
1444 Cipher name field in the payload, not including any other
1447 o Cipher Name (variable length) - Name of the cipher used
1448 in the protection of channel traffic. This name is
1449 initially decided by the creator of the channel but it
1450 may change during the life time of the channel as well.
1452 o Channel Key Length (2 bytes) - Indicates the length of the
1453 Channel Key field in the payload, not including any other
1456 o Channel Key (variable length) - The actual channel key
1457 material. This key is used as such as key material for
1458 encryption function.
1463 2.3.11 Private Message Payload
1465 Private Message Payload is used to send private message between
1466 two clients (or users for that matter). The messages are sent only
1467 to the specified user and no other user inside SILC network is
1468 able to see the message. The message is protected by the session
1469 key established by the SILC Key Exchange Protocol. However,
1470 it is also possible to agree to use specific keys to protect
1471 just the private messages. See section 2.3.11 Private Message
1472 Key Payload for detailed description of how to agree to use
1475 If normal session key is used to protect the message, every
1476 server between the sender client and the receiving client needs
1477 to decrypt the packet and always re-encrypt it with the session
1478 key of the next receiver of the packet. See section Client
1479 To Client in [SILC1].
1481 When specific key is used to protect the message, servers between
1482 the sender and the receiver needs not to decrypt/re-encrypt the
1483 packet. Section 4.8.2 Client To Client in [SILC1] gives example of
1484 this scheme as well.
1486 The payload may only be sent with SILC_PACKET_PRIVATE_MESSAGE
1487 packet. It must not be sent in any other packet type. The following
1488 diagram represents the Private Message Payload.
1494 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
1495 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1496 | Nickname Length | |
1497 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1501 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1505 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1509 Figure 13: Private Message Payload
1513 o Nickname Length (2 bytes) - Indicates the length of the
1514 Nickname field, not including any other field.
1516 o Nickname (variable length) - Nickname of the sender of the
1517 private message. This should not be trusted as a definite
1518 sender of the private message. The SILC Packet Header in
1519 the packet indicates the true sender of the packet and
1520 client should verify that the nickname sent here belongs
1521 to the Client ID in the SILC Packet Header. This nickname
1522 is merely provided to be displayed by the client.
1524 o Message Data (variable length) - The actual message to
1525 the client. Rest of the packet is reserved for the message
1531 2.3.12 Private Message Key Payload
1533 This payload is used to send key from client to another client that
1534 is going to be used to protect the private messages between these
1535 two clients. If this payload is not sent normal session key
1536 established by the SILC Key Exchange Protocol is used to protect
1537 the private messages.
1539 This payload may only be sent by client to another client. Server
1540 must not send this payload at any time. After sending this payload
1541 the sender of private messages must set the Private Message Key
1542 flag into SILC Packet Header.
1544 The payload may only be sent with SILC_PACKET_PRIVATE_MESSAGE_KEY
1545 packet. It must not be sent in any other packet type. The following
1546 diagram represents the Private Message Key Payload.
1552 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
1553 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1554 | Private Message Key Length | |
1555 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1557 ~ Private Message Key ~
1559 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1560 | Cipher Name Length | |
1561 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1565 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1569 Figure 14: Private Message Key Payload
1575 o Private Message Key Length (2 bytes) - Indicates the length
1576 of the Private Message Key field in the payload, not including
1579 o Private Message Key (variable length) - The actual private
1580 message key material.
1582 o Cipher Name Length (2 bytes) - Indicates the length of the
1583 Cipher Name field in the payload, not including any other
1586 o Cipher Name (variable length) - Name of the cipher to use
1587 in the private message encryption. If this field does not
1588 exist then the default cipher of the SILC protocol is used.
1589 See the [SILC1] for defined ciphers.
1595 2.3.13 Command Payload
1597 Command Payload is used to send SILC commands from client to server.
1598 Also server may send commands to other servers. The following diagram
1599 represents the Command Payload.
1605 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
1606 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1607 | Payload Length | SILC Command | Arguments Num |
1608 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1609 | Command Identifier |
1610 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1614 Figure 15: Command Payload
1618 o Payload Length (2 bytes) - Length of the entire command
1619 payload including any command argument payloads associated
1622 o SILC Command (1 byte) - Indicates the SILC command. This must
1623 be set to non-zero value. If zero (0) value is found in this
1624 field the packet must be discarded.
1626 o Arguments Num (1 byte) - Indicates the number of arguments
1627 associated with the command. If there are no arguments this
1628 field is set to zero (0). The arguments must follow the
1629 command payload. See section 2.3.2.2 for definition of the
1632 o Command Identifier (2 bytes) - Identifies this command at the
1633 sender's end. The entity who replies to this command must
1634 set the value found from this field into the Command Payload
1635 used to send the reply to the sender. This way the sender
1636 can identify which command reply belongs to which originally
1637 sent command. What this field includes is implementation
1638 issue but it is recommended that wrapping counter value is
1639 used in the field. Value zero (0) in this field means that
1640 no specific value is set.
1643 See [SILC1] for detailed description of different SILC commands,
1644 their arguments and their reply messages.
1648 2.3.14 Command Reply Payload
1650 Command Reply Payload is used to send replies to the commands. The
1651 Command Reply Payload is identical to the Command Payload thus see the
1652 upper sections for Command Payload and for Command Argument Payload
1653 specifications. Command Reply message uses the Command Argument Payload
1656 The entity who sends the reply packet must set the Command Unifier
1657 field in the reply packet's Command Payload to the value it received
1658 in the original command packet.
1660 See SILC Commands in [SILC1] for detailed description of different
1661 SILC commands, their arguments and their reply messages.
1665 2.3.15 Connection Auth Request Payload
1667 Client may send this payload to server to request the authentication
1668 method that must be used in authentication protocol. If client knows
1669 this information beforehand this payload is not necessary to be sent.
1670 Server performing authentication with another server may also send
1671 this payload to request the authentication method. If the connecting
1672 server already knows this information this payload is not necessary
1675 Server receiving this request must reply with same payload sending
1676 the mandatory authentication method. Algorithms that may be required
1677 to be used by the authentication method are the ones already
1678 established by the SILC Key Exchange protocol. See section Key
1679 Exchange Start Payload in [SILC3] for detailed information.
1681 The payload may only be sent with SILC_PACKET_CONNECTION_AUTH_REQUEST
1682 packet. It must not be sent in any other packet type. The following
1683 diagram represents the Connection Auth Request Payload.
1689 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
1690 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1691 | Connection Type | Authentication Method |
1692 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1696 Figure 16: Connection Auth Request Payload
1700 o Connection Type (2 bytes) - Indicates the type of the ID.
1701 The following connection types are defined:
1707 If any other type is found in this field the packet must be
1708 discarded and the authentication must be failed.
1710 o Authentication Method (2 bytes) - Indicates the authentication
1711 method to be used in the authentication protocol. The following
1712 authentication methods are defined:
1717 1 password (mandatory)
1718 2 public key (mandatory)
1720 If any other type is found in this field the packet must be
1721 discarded and the authentication must be failed. If this
1722 payload is sent as request to receive the mandatory
1723 authentication method this field must be set to zero (0),
1724 indicating that receiver should send the mandatory
1725 authentication method. The receiver sending this payload
1726 to the requesting party, may also set this field to zero (0)
1727 to indicate that authentication is not required. In this
1728 case authentication protocol still must be started but
1729 server is most likely to respond with SILC_PACKET_SUCCESS
1735 2.3.16 New ID Payload
1737 New ID Payload is a multipurpose payload. It is used to send newly
1738 created ID's from clients and servers. When client connects to server
1739 and registers itself to the server by sending SILC_PACKET_NEW_CLIENT
1740 packet, server replies with this packet by sending the created ID for
1741 the client. Server always creates the ID for the client.
1743 This payload is also used when server tells its router that new client
1744 has registered to the SILC network. In this case the server sends
1745 the Client ID of the client to the router. Similary when router
1746 distributes information to other routers about the client in the SILC
1747 network this payload is used.
1749 Also, when server connects to router, router uses this payload to inform
1750 other routers about new server in the SILC network. However, every
1751 server (or router) creates their own ID's thus the ID distributed by
1752 this payload is not created by the distributor in this case. Servers
1753 create their own ID's. Server registers itself to the network by sending
1754 SILC_PACKET_NEW_SERVER to the router it connected to. The case is same
1755 when router connects to another router.
1757 However, this payload is not and must not be used to send information
1758 about new channels. New channels are always distributed by sending the
1759 dedicated SILC_PACKET_NEW_CHANNEL packet.
1761 Hence, this payload is very important and used every time when some
1762 new entity is registered to the SILC network. Client never sends this
1763 payload. Both client and server (and router) may receive this payload.
1765 The packet uses generic ID Payload as New ID Payload. See section
1766 2.3.2.1 for generic ID Payload.
1770 2.3.17 New Client Payload
1772 When client is connected to the server, keys has been exchanged and
1773 connection has been authenticated client must register itself to the
1774 server. Clients first packet after key exchange and authentication
1775 protocols must be SILC_PACKET_NEW_CLIENT. This payload tells server all
1776 the relevant information about the connected user. Server creates a new
1777 client ID for the client when received this payload and sends it to the
1778 client in New ID Payload.
1780 This payload sends username and real name of the user on the remote host
1781 which is connected to the SILC server with SILC client. The server
1782 creates the client ID according the information sent in this payload.
1783 The nickname of the user becomes the username sent in this payload.
1784 However, client should call NICK command after sending this payload to
1785 set the real nickname of the user which is then used to create new
1788 The payload may only be sent with SILC_PACKET_NEW_CLIENT packet. It
1789 must not be sent in any other packet type. The following diagram represents
1790 the New Client Payload.
1797 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
1798 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1799 | Username Length | |
1800 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1804 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1805 | Real Name Length | |
1806 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1810 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1814 Figure 17: New Client Payload
1818 o Username Length (2 bytes) - Length of the username.
1820 o Username (variable length) - The username of the user on
1821 the host where connecting to the SILC server.
1823 o Real Name Length (2 bytes) - Length of the Real Name.
1825 o Real Name (variable length) - The real name of the user
1826 on the host where connecting to the SILC server.
1831 2.3.18 New Server Payload
1833 This payload is sent by server when it has completed successfully both
1834 key exchange and connection authentication protocols. The server
1835 uses this payload to register itself to the SILC network. The
1836 first packet after these key exchange and authentication protocols
1837 is SILC_PACKET_NEW_SERVER packet. The payload includes the Server ID
1838 of the server that it has created by itself. It also includes a
1839 name of the server that is associated to the Server ID.
1841 The payload may only be sent with SILC_PACKET_NEW_SERVER packet. It
1842 must not be sent in any other packet type. The following diagram represents
1843 the New Server Payload.
1852 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
1853 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1854 | Server ID Length | |
1855 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1859 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1860 | Server Name Length | |
1861 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1865 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1869 Figure 18: New Server Payload
1873 o Server ID Length (2 bytes) - Length of the ID Data area not
1874 including the length of any other fields in the payload.
1876 o Server ID Data (variable length) - The actual Server ID
1879 o Server Name Length (2 bytes) - Length of the server name.
1881 o Server Name (variable length) - The server name.
1886 2.3.19 New Channel Payload
1888 Information about newly created channel is broadcasted to all routers
1889 in the SILC network by sending this packet payload. Channels are
1890 created by router of the cell. Server never creates channels unless
1891 it is a standalone server and it does not have router connection,
1892 in this case server acts as router. Normal server send JOIN command
1893 to the router (after it has received JOIN command from client) which
1894 then processes the command and creates the channel. Client never sends
1897 The payload may only be sent with SILC_PACKET_NEW_CHANNEL packet.
1898 It must not be sent in any other packet type. The following diagram
1899 represents the New Channel Payload.
1905 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
1906 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1907 | Channel Name Length | |
1908 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1912 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1913 | Channel ID Length | |
1914 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1918 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1922 Figure 19: New Channel Payload
1927 o Channel Name Length (2 bytes) - Length of the channel name.
1929 o Channel Name (variable length) - The name of the created
1932 o Channel ID Length (2 bytes) - Length of the Channel ID.
1934 o Channel ID (variable length) - The created Channel ID.
1939 2.3.20 Key Agreement Payload
1941 This payload is used by clients to request key negotiation between
1942 another client in the SILC Network. The key agreement protocol used
1943 is the SKE protocol. The result of the protocol, the secret key
1944 material, can be used for example as private message key between the
1945 two clients. This significantly adds security as the key agreement
1946 is performed outside the SILC network. The server and router must not
1949 The sender may tell the receiver of this payload the hostname and the
1950 port where the SKE protocol is running in the sender's end. The
1951 receiver may then initiate the SKE negotiation with the sender. The
1952 sender may also optionally not to include the hostname and the port
1953 of its SKE protocol. In this case the receiver may reply to the
1954 request by sending the same payload filled with the receiver's hostname
1955 and the port where the SKE protocol is running. The sender may then
1956 initiate the SKE negotiation with the receiver.
1958 The payload may only be sent with SILC_PACKET_KEY_AGREEMENT packet.
1959 It must not be sent in any other packet type. The following diagram
1960 represents the Key Agreement Payload.
1966 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
1967 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1968 | Hostname Length | |
1969 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1973 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1975 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1979 Figure 20: Key Agreement Payload
1984 o Hostname Length (2 bytes) - Indicates the length of the Hostname
1987 o Hostname (variable length) - The hostname or IP address where
1988 the SKE protocol is running. The sender may fill this field
1989 when sending the payload. If the receiver sends this payload
1990 as reply to the request it must fill this field.
1992 o Port (4 bytes) - The port where the SKE protocol is bound.
1993 The sender may fill this field when sending the payload. If
1994 the receiver sends this payload as reply to the request it
1995 must fill this field. This is a 32 bit MSB first order value.
1999 After the key material has been received from the SKE protocol it is
2000 processed as the [SILC3] describes. If the key material is used as
2001 channel private key then the Sending Encryption Key, as defined in
2002 [SILC3] is used as the channel private key. Other key material must
2003 be discarded. The [SILC1] defines the way to use the key material if
2004 it is intended to be used as private message keys. Any other use for
2005 the key material is undefined.
2011 ID's are extensively used in the SILC network to associate different
2012 entities. The following ID's has been defined to be used in the SILC
2018 When ever specific ID cannot be used this is used.
2022 Server ID to associate servers. See the format of
2027 Client ID to associate clients. See the format of
2032 Channel ID to associate channels. See the format of
2038 2.5 Packet Encryption And Decryption
2040 SILC packets are encrypted almost entirely. Only small part of SILC
2041 header is not encrypted as described in section 5.2 SILC Packet Header.
2042 The SILC Packet header is the first part of a packet to be encrypted
2043 and it is always encrypted with the key of the next receiver of the
2044 packet. The data payload area of the packet is always entirely
2045 encrypted and it is usually encrypted with the next receiver's key.
2046 However, there are some special packet types and packet payloads
2047 that require special encryption process. These special cases are
2048 described in the next sections. First is described the normal packet
2053 2.5.1 Normal Packet Encryption And Decryption
2055 Normal SILC packets are encrypted with the session key of the next
2056 receiver of the packet. The entire SILC Packet header and the packet
2057 data payload is is also encrypted with the same key. Padding of the
2058 packet is also encrypted always with the session key, also in special
2059 cases. Computed MAC of the packet must not be encrypted.
2061 Decryption process in these cases are straightforward. The receiver
2062 of the packet must first decrypt the SILC Packet header, or some parts
2063 of it, usually first 16 bytes of it. Then the receiver checks the
2064 packet type from the decrypted part of the header and can determine
2065 how the rest of the packet must be decrypted. If the packet type is
2066 any of the special cases described in The following sections the packet
2067 decryption is special. If the packet type is not among those special
2068 packet types rest of the packet may be decrypted with the same key.
2070 Also, note that two bytes of the SILC Packet header are not encrypted
2071 thus it must be noticed in the decryption process by starting the
2072 decryption from the second byte of the header. This sets some rules
2073 to padding generation as well, see the section 2.7 Packet Padding
2076 With out a doubt, this sort of decryption processing causes some
2077 overhead to packet decryption, but never the less, is required.
2081 2.5.2 Channel Message Encryption And Decryption
2083 Channel Messages (Channel Message Payload) are always encrypted with
2084 the channel specific key. However, the SILC Packet header is not
2085 encrypted with that key. As in normal case, the header is encrypted
2086 with the key of the next receiver of the packet, who ever that might
2087 be. Note that in this case the encrypted data area is not touched
2088 at all; it must not be re-encrypted with the session key.
2090 Receiver of a channel message, who ever that is, is required to decrypt
2091 the SILC Packet header to be able to even recognize the packet to be as
2092 channel message. This is same procedure as for normal SILC packets.
2093 As the receiver founds the packet to be channel message, rest of the
2094 packet processing is special. Rest of the SILC Packet header is
2095 decrypted with the same session key along with the padding of the
2096 packet. After that the packet is protected with the channel specific
2097 key and thus can be decrypted only if the receiver is the client on
2098 the channel. See section 2.7 Packet Padding Generation for more
2099 information about padding on special packets.
2101 If the receiver of the channel message is router who is routing the
2102 message to another router then it must decrypt the Channel Message
2103 payload. Between routers (that is, between cells) channel messages
2104 are protected with session keys shared between the routers. This
2105 causes another special packet processing for channel messages. If
2106 the channel message is received from another router then the entire
2107 packet, including Channel Message payload, is encrypted with the
2108 session key shared between the routers. In this case the packet
2109 decryption process is as with normal SILC packets. Hence, if the
2110 router is sending channel message to another router the Channel
2111 Message payload must have been decrypted and must be re-encrypted
2112 with the session key shared between the another router. In this
2113 case the packet encryption is as with any normal SILC packet.
2115 It must be noted that this is only when the channel messages are sent
2116 from router to another router. In all other cases the channel
2117 message encryption and decryption is as described above. This
2118 different processing of channel messages with router to router
2119 connection is because channel keys are cell specific. All cells has
2120 their own channel keys thus the channel message traveling from one
2121 cell to another must be protected as it would be any normal SILC
2126 2.5.3 Private Message Encryption And Decryption
2128 By default, private message in SILC are protected by session keys.
2129 In this case the private message encryption and decryption process is
2130 equivalent to normal packet encryption and decryption.
2132 However, private messages can be protected with private message key
2133 which causes the packet to be special packet. The procedure in this
2134 case is very much alike to channel packets. The actual private message
2135 is encrypted with the private message key and other parts of the
2136 packet is encrypted with the session key. See 2.7 Packet Padding
2137 Generation for more information about padding on special packets.
2139 The difference from channel message processing is that server or router
2140 en route never decrypts the actual private message, as it does not
2141 have the key to do that. Thus, when sending packets between router
2142 the processing is same as in any other case as well; the packet's header
2143 and padding is protected by the session key and the data area is not
2146 The true receiver of the private message, client, that is, is able
2147 to decrypt the private message as it shares the key with the sender
2152 2.6 Packet MAC Generation
2154 Data integrity of a packet is protected by including a message
2155 authentication code (MAC) at the end of the packet. The MAC is computed
2156 from shared secret MAC key, that is established by the SILC Key Exchange
2157 protocol, and from the original contents of the packet. The MAC is
2158 always computed before the packet is encrypted, although after it is
2159 compressed if compression is used.
2161 The MAC is computed from entire packet. Every bit of data in the packet,
2162 including SILC Packet Header is used in the MAC computing. This way
2163 the entire packet becomes authenticated.
2165 If the packet is special packet MAC is computed from the entire packet
2166 but part of the packet may be encrypted before the MAC is computed.
2167 This is case, for example, with channel messages where the message data
2168 is encrypted with key that server may not now. In this case the MAC
2169 has been computed from the encrypted data.
2171 See [SILC1] for defined and allowed MAC algorithms.
2175 2.7 Packet Padding Generation
2177 Padding is needed in the packet because the packet is encrypted. It
2178 must always be multiple by eight (8) or multiple by the size of the
2179 cipher's block size, which ever is larger. The padding is always
2182 For normal packets the padding is added after the SILC Packet Header
2183 and between the Data Payload area. The padding for normal packets
2184 are calculated as follows:
2187 padding length = 16 - ((packet length - 2) % 16)
2190 The 16 is the maximum padding allowed in SILC packet. Two (2) is
2191 subtracted from the true length of the packet because two (2) bytes
2192 is not encrypted in SILC Packet Header, see section 2.2 SILC Packet
2193 Header. Those two bytes that are not encrypted must not be calculated
2194 to the padding length.
2196 For special packets the padding calculation may be different as special
2197 packets may be encrypted differently. In these cases the encrypted
2198 data area must already be multiple by the block size thus in this case
2199 the padding is calculated only for SILC Packet Header, not for any
2200 other area of the packet. The same algorithm works in this case as
2201 well, except that the `packet length' is now the SILC Packet Header
2202 length. In this case, as well, two (2) is subtracted from the
2205 The padding must be random data, preferably, generated by
2206 cryptographically strong random number generator.
2210 2.8 Packet Compression
2212 SILC Packets may be compressed. In this case the data payload area
2213 is compressed and all other areas of the packet must remain as they
2214 are. After compression is performed for the data area, the length
2215 field of Packet Header must be set to the compressed length of the
2218 The compression must always be applied before encryption. When
2219 the packet is received and decrypted the data area must be decompressed.
2220 Note that the true sender of the packet must apply the compression and
2221 the true receiver of the packet must apply the decompression. Any
2222 server or router en route must not decompress the packet.
2229 The sender of the packet must assemble the SILC Packet Header with
2230 correct values. It must set the Source ID of the header as its own
2231 ID, unless it is forwarding the packet. It must also set the Destination
2232 ID of the header to the true destination. If the destination is client
2233 it will be Client ID, if it is server it will be Server ID and if it is
2234 channel it will be Channel ID.
2236 If the sender wants to compress the packet it must apply the
2237 compression now. Sender must also compute the padding as described
2238 in above sections. Then sender must compute the MAC of the packet.
2240 Then sender encrypts the packet as has been described in above
2241 sections according whether the packet is normal packet or special
2242 packet. The computed MAC must not be encrypted.
2246 2.10 Packet Reception
2248 On packet reception the receiver must check that all fields in the
2249 SILC Packet Header are valid. It must check the flags of the
2250 header and act accordingly. It must also check the MAC of the packet
2251 and if it is to be failed the packet must be discarded. Also if the
2252 header of the packet includes any bad fields the packet must be
2255 See above sections on the decryption process of the received packet.
2257 The receiver must also check that the ID's in the header are valid
2258 ID's. Unsupported ID types or malformed ID's must cause packet
2259 rejection. The padding on the reception is always ignored.
2261 The receiver must also check the packet type and start parsing the
2262 packet according to the type. However, note the above sections on
2263 special packet types and their parsing.
2269 Routers are the primary entities in the SILC network that takes care
2270 of packet routing. However, normal servers routes packets as well, for
2271 example, when they are routing channel message to the local clients.
2272 Routing is quite simple as every packet tells the true origin and the
2273 true destination of the packet.
2275 It is still recommended for routers that has several routing connections
2276 to create route cache for those destinations that has faster route than
2277 the router's primary route. This information is available for the router
2278 when other router connects to the router. The connecting party then
2279 sends all of its locally connected clients, server and channels. These
2280 informations helps to create the route cache. Also, when new channels
2281 are created to a cell its information is broadcasted to all routers
2282 in the network. Channel ID's are based on router's ID thus it is easy
2283 to create route cache based on these informations. If faster route for
2284 destination does not exist in router's route cache the packet must be
2285 routed to the primary route (default route).
2287 For server who receives a packet to be routed to its locally connected
2288 client the server must check whether the particular packet type is
2289 allowed to be routed to the client. Not all packets may be sent by
2290 some odd entity to client that is indirectly connected to the sender.
2291 See section 2.3 SILC Packet Types and paragraph about indirectly connected
2292 entities and sending packets to them. The section mentions the packets
2293 that may be sent to indirectly connected entities. It is clear that some
2294 server cannot send, for example, disconnect packet to client that is not
2295 directly connected to the server.
2299 2.12 Packet Broadcasting
2301 SILC packets may be broadcasted in SILC network. However, only router
2302 server may send or receive broadcast packets. Client and normal server
2303 must not send broadcast packets and they must ignore broadcast packets
2304 if they receive them. Broadcast packets are sent by setting Broadcast
2305 flag to the SILC packet header.
2307 Broadcasting packets means that the packet is sent to all routers in
2308 the SILC network, except to the router that sent the packet. The router
2309 receiving broadcast packet must send the packet to its primary route.
2310 The fact that SILC routers may have several router connections may
2311 cause problems, such as race conditions inside the SILC network, if
2312 care is not taken when broadcasting packets. Router must not send
2313 the broadcast packet to any other route except to its primary route.
2315 If the primary route of the router is the original sender of the packet
2316 the packet must not be sent to the primary route. This may happen
2317 if router has several router connections and some other router uses
2318 the router as its primary route.
2320 Routers use broadcast packets to broadcast for example information
2321 about newly registered clients, servers, channels etc. so that all the
2322 routers may keep these informations up to date.
2326 2.13 Packet Tunneling
2328 Tunneling is a feature that is available in SILC protocol. Tunneling
2329 means that extra SILC Packet Header is applied to the original packet
2330 and thus hiding the original packet entirely. There can be some
2331 interesting applications using tunneling, such as, using ID's based on
2332 private network IP addresses inside in the tunneled packet. This can
2333 open many interesting features relating to connecting to private network
2334 from the Internet with SILC and many more. However, this feature is
2335 optional currently in SILC as there does not exist thorough analysis of
2336 this feature. It is with out a doubt that there will be many more
2337 applications that has not yet been discovered. Thus, it is left
2338 to Internet Community to investigate the use of tunneling in SILC
2339 protocol. This document is updated according those investigations
2340 and additional documents on the issue may be written.
2344 3 Security Considerations
2346 Security is central to the design of this protocol, and these security
2347 considerations permeate the specification. Common security considerations
2348 such as keeping private keys truly private and using adequate lengths for
2349 symmetric and asymmetric keys must be followed in order to maintain the
2350 security of this protocol.
2356 [SILC1] Riikonen, P., "Secure Internet Live Conferencing (SILC),
2357 Protocol Specification", Internet Draft, June 2000.
2359 [SILC3] Riikonen, P., "SILC Key Exchange and Authentication
2360 Protocols", Internet Draft, June 2000.
2362 [IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
2365 [IRC-ARCH] Kalt, C., "Internet Relay Chat: Architecture", RFC 2810,
2368 [IRC-CHAN] Kalt, C., "Internet Relay Chat: Channel Management", RFC
2371 [IRC-CLIENT] Kalt, C., "Internet Relay Chat: Client Protocol", RFC
2374 [IRC-SERVER] Kalt, C., "Internet Relay Chat: Server Protocol", RFC
2377 [SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
2380 [PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
2383 [SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
2386 [PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
2387 Infrastructure, Certificate and CRL Profile", RFC 2459,
2390 [Schneier] Schneier, B., "Applied Cryptography Second Edition",
2391 John Wiley & Sons, New York, NY, 1996.
2393 [Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
2396 [OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
2397 RFC 2412, November 1998.
2399 [ISAKMP] Maughan D., et al, "Internet Security Association and
2400 Key Management Protocol (ISAKMP)", RFC 2408, November
2403 [IKE] Harkins D., and Carrel D., "The Internet Key Exchange
2404 (IKE)", RFC 2409, November 1998.
2406 [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
2407 Authentication", RFC 2104, February 1997.
2409 [PKCS1] Kalinski, B., and Staddon, J., "PKCS #1 RSA Cryptography
2410 Specifications, Version 2.0", RFC 2437, October 1998.
2422 EMail: priikone@poseidon.pspt.fi
2424 This Internet-Draft expires 6 Jun 2001