8 .ds RF FORMFEED[Page %]
17 Network Working Group P. Riikonen
19 draft-riikonen-silc-pp-05.txt 15 May 2002
20 Expires: 15 November 2002
26 <draft-riikonen-silc-pp-05.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
34 areas, and its working groups. Note that other groups may also
35 distribute working documents as Internet-Drafts.
37 Internet-Drafts are draft documents valid for a maximum of six months
38 and may be updated, replaced, or obsoleted by other documents at any
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
43 http://www.ietf.org/ietf/1id-abstracts.txt
45 The list of Internet-Draft Shadow Directories can be accessed at
46 http://www.ietf.org/shadow.html
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
73 1 Introduction .................................................. 3
74 1.1 Requirements Terminology .................................. 4
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 ......................................... 8
79 2.3.1 SILC Packet Payloads ................................ 17
80 2.3.2 Generic payloads .................................... 17
81 2.3.2.1 ID Payload .................................. 17
82 2.3.2.2 Argument Payload ............................ 18
83 2.3.2.3 Channel Payload ............................. 19
84 2.3.2.4 Public Key Payload .......................... 20
85 2.3.3 Disconnect Payload .................................. 20
86 2.3.4 Success Payload ..................................... 21
87 2.3.5 Failure Payload ..................................... 22
88 2.3.6 Reject Payload ...................................... 22
89 2.3.7 Notify Payload ...................................... 23
90 2.3.8 Error Payload ....................................... 31
91 2.3.9 Channel Message Payload ............................. 31
92 2.3.10 Channel Key Payload ................................ 35
93 2.3.11 Private Message Payload ............................ 36
94 2.3.12 Private Message Key Payload ........................ 38
95 2.3.13 Command Payload .................................... 39
96 2.3.14 Command Reply Payload .............................. 40
97 2.3.15 Connection Auth Request Payload .................... 40
98 2.3.16 New ID Payload ..................................... 42
99 2.3.17 New Client Payload ................................. 42
100 2.3.18 New Server Payload ................................. 43
101 2.3.19 New Channel Payload ................................ 44
102 2.3.20 Key Agreement Payload .............................. 45
103 2.3.21 Resume Router Payload .............................. 46
104 2.3.22 File Transfer Payload .............................. 46
105 2.3.23 Resume Client Payload .............................. 48
106 2.4 SILC ID Types ............................................. 49
107 2.5 Packet Encryption And Decryption .......................... 49
108 2.5.1 Normal Packet Encryption And Decryption ............. 50
109 2.5.2 Channel Message Encryption And Decryption ........... 50
110 2.5.3 Private Message Encryption And Decryption ........... 51
111 2.6 Packet MAC Generation ..................................... 52
112 2.7 Packet Padding Generation ................................. 52
113 2.8 Packet Compression ........................................ 53
114 2.9 Packet Sending ............................................ 53
115 2.10 Packet Reception ......................................... 54
116 2.11 Packet Routing ........................................... 54
117 2.12 Packet Broadcasting ...................................... 55
118 3 Security Considerations ....................................... 56
119 4 References .................................................... 56
120 5 Author's Address .............................................. 58
126 Figure 1: Typical SILC Packet
127 Figure 2: SILC Packet Header
129 Figure 4: Argument Payload
130 Figure 5: Channel Payload
131 Figure 6: Public Key Payload
132 Figure 7: Disconnect Payload
133 Figure 8: Success Payload
134 Figure 9: Failure Payload
135 Figure 10: Reject Payload
136 Figure 11: Notify Payload
137 Figure 12: Error Payload
138 Figure 13: Channel Message Payload
139 Figure 14: Channel Key Payload
140 Figure 15: Private Message Payload
141 Figure 16: Private Message Key Payload
142 Figure 17: Command Payload
143 Figure 18: Connection Auth Request Payload
144 Figure 19: New Client Payload
145 Figure 20: New Server Payload
146 Figure 21: Key Agreement Payload
147 Figure 22: Resume Router Payload
148 Figure 23: File Transfer Payload
149 Figure 24: Resume Client Payload
155 This document describes a Packet Protocol used in the Secure Internet
156 Live Conferencing (SILC) protocol specified in the Secure Internet Live
157 Conferencing, Protocol Specification Internet Draft [SILC1]. This
158 protocol describes the packet types and packet payloads which defines
159 the contents of the packets. The protocol provides secure binary packet
160 protocol that assures that the contents of the packets are secured and
161 authenticated. The packet protocol is designed to be compact to avoid
162 unnecessary overhead as much as possible. This makes the SILC suitable
163 also in environment of low bandwidth requirements such as mobile networks.
164 All packet payloads can also be compressed to further reduce the size
167 The basis of SILC protocol relies in the SILC packets and it is with
168 out a doubt the most important part of the protocol. It is also probably
169 the most complicated part of the protocol. Packets are used all the
170 time in the SILC network to send messages, commands and other information.
171 All packets in SILC network are always encrypted and their integrity
172 is assured by computed MACs. The protocol defines several packet types
173 and packet payloads. Each packet type usually has a specific packet
174 payload that actually defines the contents of the packet. Each packet
175 also includes a default SILC Packet Header that provides sufficient
176 information about the origin of the packet and destination of the
181 1.1 Requirements Terminology
183 The keywords MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT, RECOMMENDED,
184 MAY, and OPTIONAL, when they appear in this document, are to be
185 interpreted as described in [RFC2119].
189 2 SILC Packet Protocol
194 SILC packets deliver messages from sender to receiver securely by
195 encrypting important fields of the packet. The packet consists of
196 default SILC Packet Header, Padding, Packet Payload data, and, packet
199 The following diagram illustrates typical SILC packet.
204 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
205 | n bytes | 1 - n bytes | n bytes | n bytes
206 | SILC Header | Padding | Data Payload | MAC
207 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
211 Figure 1: Typical SILC Packet
214 SILC Header is always the first part of the packet and its purpose
215 is to provide information about the packet. It provides for example
216 the packet type, origin of the packet and the destination of the packet.
217 The header is variable in length. See the following section for
218 description of SILC Packet header. Packets without SILC header or
219 with malformed SILC header MUST be dropped.
221 Padding follows the packet header. The purpose of the padding is to
222 make the packet multiple by eight (8) or by the block size of the
223 cipher used in the encryption, which ever is larger. The maximum
224 length of padding is currently 128 bytes. The padding is always
225 encrypted. The padding is applied always, even if the packet is
226 not encrypted. See the section 2.7 Padding Generation for more
227 detailed information.
229 Data payload area follows padding and it is the actual data of the
230 packet. The packet data is the packet payloads defined in this
231 protocol. The data payload area is always encrypted.
233 The last part of SILC packet is the packet MAC that assures the
234 integrity of the packet. See the section 2.6 Packet MAC Generation
235 for more information. If compression is used the compsession is
236 always applied before encryption.
238 All fields in all packet payloads are always in MSB (most significant
243 2.2 SILC Packet Header
245 The SILC packet header is applied to all SILC packets and it is
246 variable in length. The purpose of SILC Packet header is to provide
247 detailed information about the packet. The receiver of the packet
248 uses the packet header to parse the packet and gain other relevant
249 parameters of the packet.
251 The following diagram represents the SILC packet header.
256 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
257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
258 | Payload Length | Flags | Packet Type |
259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
260 | Pad Length | RESERVED | Source ID Len | Dest ID Len |
261 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
267 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
273 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
277 Figure 2: SILC Packet Header
281 o Payload Length (2 bytes) - Is the length of the packet
282 not including the padding of the packet.
284 o Flags (1 byte) - Indicates flags to be used in packet
285 processing. Several flags may be set by ORing the flags
288 The following flags are reserved for this field:
293 In this case the field is ignored.
296 Private Message Key 0x01
298 Indicates that the packet must include private
299 message that is encrypted using private key set by
300 client. Servers does not know anything about this
301 key and this causes that the private message is
302 not handled by the server at all, it is just
303 passed along. See section 2.5.3 Private Message
304 Encryption And Decryption for more information.
309 Indicates that the packet consists of list of
310 packet payloads indicated by the Packet Type field.
311 The payloads are added one after the other. Note that
312 there are packet types that must not be used as
313 list. Parsing of list packet is done by calculating
314 the length of each payload and parsing them one by
320 Marks the packet to be broadcasted. Client cannot
321 send broadcast packet and normal server cannot send
322 broadcast packet. Only router server may send broadcast
323 packet. The router receiving of packet with this flag
324 set MUST send (broadcast) the packet to its primary
325 route. If router has several router connections the
326 packet may be sent only to the primary route. See
327 section 2.12 Packet Broadcasting for description of
333 Marks that the payload of the packet is compressed.
334 The sender of the packet marks this flag when it
335 compresses the payload, and any server or router
336 en route to the recipient MUST NOT unset this flag.
337 See section 2.8 Packet Compression for description of
345 o Packet Type (1 byte) - Is the type of the packet. Receiver
346 uses this field to parse the packet. See section 2.3
347 SILC Packets for list of defined packet types.
349 o Pad Length (1 byte) - Indicates the length of the padding
350 applied after the SILC Packet header. Maximum length for
351 padding is 128 bytes.
353 o RESERVED (1 byte) - Reserved field and must include a
356 o Source ID Length (1 byte) - Indicates the length of the
357 Source ID field in the header, not including this or any
360 o Destination ID Length (1 byte) - Indicates the length of the
361 Destination ID field in the header, not including this or
364 o Src ID Type (1 byte) - Indicates the type of ID in the
365 Source ID field. See section 2.4 SILC ID Types for
368 o Source ID (variable length) - The actual source ID that
369 indicates which is the original sender of the packet.
371 o Dst ID Type (1 byte) - Indicates the type of ID in the
372 Destination ID field. See section 2.4 SILC ID Types for
375 o Destination ID (variable length) - The actual destination
376 ID that indicates which is the end receiver of the packet.
381 2.3 SILC Packet Types
383 SILC packet types defines the contents of the packet and it is used by
384 the receiver to parse the packet. The packet type is 8 bits, as a one
385 byte, in length. The range for the packet types are from 0 - 255,
386 where 0 is never sent and 255 is currently reserved for future
387 extensions and MUST NOT be defined to any other purpose. Every SILC
388 specification compliant implementation SHOULD support all of these packet
391 The below list of the SILC Packet types includes reference to the packet
392 payload as well. Packet payloads are the actual packet, that is, the data
393 that the packet consists of. Each packet type defines packet payload
394 which usually may only be sent with the specific packet type.
396 Most of the packets are packets that must be destined directly to entity
397 that is connected to the sender. It is not allowed, for example, for
398 router to send disconnect packet to client that is not directly connected
399 to the router. However, there are some special packet types that may
400 be destined to some entity that the sender has not direct connection
401 with. These packets are for example private message packets, channel
402 message packets, command packets and some other packets that may be
403 broadcasted in the SILC network. If the packet is allowed to be sent to
404 indirectly connected entity it is mentioned separately in the packet
405 description (unless it is obvious as in private and channel message
406 packets). Other packets MUST NOT be sent or accepted, if sent, to
407 indirectly connected entities.
409 List of SILC Packet types are defined as follows.
414 This type is reserved and it is never sent.
417 1 SILC_PACKET_DISCONNECT
419 This packet is sent to disconnect the remote end. Reason of
420 the disconnection is sent inside the packet payload. Client
421 usually does not send this packet.
423 This packet MUST NOT be sent as list and the List flag MUST
426 Payload of the packet: See section 2.3.3 Disconnect Payload
429 2 SILC_PACKET_SUCCESS
431 This packet is sent upon successful execution of some protocol.
432 The status of the success is sent in the packet.
434 This packet MUST NOT be sent as list and the List flag MUST
437 Payload of the packet: See section 2.3.4 Success Payload
440 3 SILC_PACKET_FAILURE
442 This packet is sent upon failure of some protocol. The status
443 of the failure is sent in the packet.
445 This packet MUST NOT be sent as list and the List flag MUST
448 Payload of the packet: See section 2.3.5 Failure Payload
453 This packet MAY be sent upon rejection of some protocol.
454 The status of the rejection is sent in the packet.
456 This packet MUST NOT be sent as list and the List flag MUST
459 Payload of the packet: See section 2.3.6 Reject Payload
464 This packet is used to send notify message, usually from
465 server to client, although it MAY be sent from server to another
466 server as well. Client MUST NOT send this packet. Server MAY
467 send this packet to channel as well when the packet is
468 distributed to all clients on the channel.
470 Payload of the packet: See section 2.3.7 Notify Payload.
476 This packet is sent when an error occurs. Server MAY
477 send this packet. Client MUST NOT send this packet. The
478 client MAY entirely ignore the packet, however, server is
479 most likely to take action anyway. This packet MAY be sent
480 to entity that is indirectly connected to the sender.
482 This packet MUST NOT be sent as list and the List flag MUST
485 Payload of the packet: See section 2.3.8 Error Payload.
488 7 SILC_PACKET_CHANNEL_MESSAGE
490 This packet is used to send messages to channels. The packet
491 includes Channel ID of the channel and the actual message to
492 the channel. Messages sent to the channel are always protected
493 by channel specific keys. Channel Keys are distributed by
494 SILC_PACKET_CHANNEL_KEY packet.
496 This packet MUST NOT be sent as list and the List flag MUST
499 Payload of the packet: See section 2.3.9 Channel Message
503 8 SILC_PACKET_CHANNEL_KEY
505 This packet is used to distribute new key for particular
506 channel. Each channel has their own independent keys that
507 is used to protect the traffic on the channel. Only server
508 may send this packet. This packet MAY be sent to entity
509 that is indirectly connected to the sender.
511 This packet MUST NOT be sent as list and the List flag MUST
514 Payload of the packet: See section 2.3.10 Channel Key Payload
517 9 SILC_PACKET_PRIVATE_MESSAGE
519 This packet is used to send private messages from client
520 to another client. By default, private messages are protected
521 by session keys established by normal key exchange protocol.
522 However, it is possible to use specific key to protect private
523 messages. SILC_PACKET_PRIVATE_MESSAGE_KEY packet is used to
524 agree the key with the remote client. Pre-shared key MAY be
525 used as well if both of the client knows it, however, it needs
526 to be agreed outside SILC. See more of this in [SILC1].
528 This packet MUST NOT be sent as list and the List flag MUST
531 Payload of the packet: See section 2.3.11 Private Message
535 10 SILC_PACKET_PRIVATE_MESSAGE_KEY
537 This packet is used to agree about a key to be used to protect
538 the private messages between two clients. If this is not sent
539 the normal session key is used to protect the private messages
540 inside SILC network. Agreeing to use specific key to protect
541 private messages adds security, as no server between the two
542 clients will be able to decrypt the private message. However,
543 servers inside SILC network are considered to be trusted, thus
544 using normal session key to protect private messages does not
545 degrade security. Whether to agree to use specific keys by
546 default or to use normal session keys by default, is
547 implementation specific issue. See more of this in [SILC1].
549 This packet MUST NOT be sent as list and the List flag MUST
552 Payload of the packet: See section 2.3.12 Private Message
556 11 SILC_PACKET_COMMAND
558 This packet is used to send commands from client to server.
559 Server MAY send this packet to other servers as well. All
560 commands are listed in their own section SILC Command Types
561 in [SILC4]. The contents of this packet is command specific.
562 This packet MAY be sent to entity that is indirectly connected
565 This packet MUST NOT be sent as list and the List flag MUST
568 Payload of the packet: See section 2.3.13 Command Payload
571 12 SILC_PACKET_COMMAND_REPLY
573 This packet is sent as reply to the SILC_PACKET_COMMAND packet.
574 The contents of this packet is command specific. This packet
575 MAY be sent to entity that is indirectly connected to the
578 This packet MUST NOT be sent as list and the List flag MUST
581 Payload of the packet: See section 2.3.14 Command Reply
582 Payload and section 2.3.13 Command
588 13 SILC_PACKET_KEY_EXCHANGE
590 This packet is used to start SILC Key Exchange Protocol,
591 described in detail in [SILC3].
593 This packet MUST NOT be sent as list and the List flag MUST
596 Payload of the packet: Payload of this packet is described
597 in the section SILC Key Exchange
598 Protocol and its sub sections in
602 14 SILC_PACKET_KEY_EXCHANGE_1
604 This packet is used as part of the SILC Key Exchange Protocol.
606 This packet MUST NOT be sent as list and the List flag MUST
609 Payload of the packet: Payload of this packet is described
610 in the section SILC Key Exchange
611 Protocol and its sub sections in
615 15 SILC_PACKET_KEY_EXCHANGE_2
617 This packet is used as part of the SILC Key Exchange Protocol.
619 This packet MUST NOT be sent as list and the List flag MUST
622 Payload of the packet: Payload of this packet is described
623 in the section SILC Key Exchange
624 Protocol and its sub sections in
628 16 SILC_PACKET_CONNECTION_AUTH_REQUEST
630 This packet is used to request the authentication method to
631 be used in the SILC Connection Authentication Protocol. If
632 initiator of the protocol does not know the mandatory
633 authentication method this packet MAY be used to determine it.
635 The party receiving this payload MUST respond with the same
636 packet including the mandatory authentication method.
638 This packet MUST NOT be sent as list and the List flag MUST
641 Payload of the packet: See section 2.3.15 Connection Auth
647 17 SILC_PACKET_CONNECTION_AUTH
649 This packet is used to start and perform the SILC Connection
650 Authentication Protocol. This protocol is used to authenticate
651 the connecting party. The protocol is described in detail in
654 This packet MUST NOT be sent as list and the List flag MUST
657 Payload of the packet: Payload of this packet is described
658 in the section SILC Authentication
659 Protocol and it sub sections in [SILC].
662 18 SILC_PACKET_NEW_ID
664 This packet is used to distribute new ID's from server to
665 router and from router to all routers in the SILC network.
666 This is used when for example new client is registered to
667 SILC network. The newly created ID's of these operations are
668 distributed by this packet. Only server may send this packet,
669 however, client MUST be able to receive this packet. This
670 packet MAY be sent to entity that is indirectly connected
673 Payload of the packet: See section 2.3.16 New ID Payload
676 19 SILC_PACKET_NEW_CLIENT
678 This packet is used by client to register itself to the
679 SILC network. This is sent after key exchange and
680 authentication protocols has been completed. Client sends
681 various information about itself in this packet.
683 This packet MUST NOT be sent as list and the List flag MUST
686 Payload of the packet: See section 2.3.17 New Client Payload
689 20 SILC_PACKET_NEW_SERVER
691 This packet is used by server to register itself to the
692 SILC network. This is sent after key exchange and
693 authentication protocols has been completed. Server sends
694 this to the router it connected to, or, if router was
695 connecting, to the connected router. Server sends its
696 Server ID and other information in this packet. The client
697 MUST NOT send or receive this packet.
699 This packet MUST NOT be sent as list and the List flag MUST
702 Payload of the packet: See section 2.3.18 New Server Payload
705 21 SILC_PACKET_NEW_CHANNEL
707 This packet is used to notify routers about newly created
708 channel. Channels are always created by the router and it MUST
709 notify other routers about the created channel. Router sends
710 this packet to its primary route. Client MUST NOT send this
711 packet. This packet MAY be sent to entity that is indirectly
712 connected to the sender.
714 Payload of the packet: See section 2.3.19 New Channel Payload
719 This packet is used to indicate that re-key must be performed
720 for session keys. See section Session Key Regeneration in
721 [SILC1] for more information. This packet does not have
724 This packet MUST NOT be sent as list and the List flag MUST
728 23 SILC_PACKET_REKEY_DONE
730 This packet is used to indicate that re-key is performed and
731 new keys must be used hereafter.
733 This packet MUST NOT be sent as list and the List flag MUST
737 24 SILC_PACKET_HEARTBEAT
739 This packet is used by clients, servers and routers to keep the
740 connection alive. It is recommended that all servers implement
741 keepalive actions and perform it to both direction in a link.
742 This packet does not have a payload.
744 This packet MUST NOT be sent as list and the List flag MUST
748 25 SILC_PACKET_KEY_AGREEMENT
750 This packet is used by clients to request key negotiation
751 between another client in the SILC network. If the negotiation
752 is started it is performed using the SKE protocol. The result of
753 the negotiation, the secret key material, can be used for
754 example as private message key. The server and router MUST NOT
757 This packet MUST NOT be sent as list and the List flag MUST
760 Payload of the packet: See section 2.3.20 Key Agreement Payload
765 26 SILC_PACKET_RESUME_ROUTER
767 This packet is used during backup router protocol when the
768 original primary router of the cell comes back online and wishes
769 to resume the position as being the primary router of the cell.
771 Payload of the packet: See section 2.3.21 Resume Router Payload
776 This packet is used to perform an file transfer protocol in the
777 SILC session with some entity in the network. The packet is
778 multi purpose. The packet is used to tell other entity in the
779 network that the sender wishes to perform an file transfer
780 protocol. The packet is also used to actually tunnel the
781 file transfer protocol stream. The file transfer protocol
782 stream is always protected with the SILC packet.
784 This packet MUST NOT be sent as list and the List flag MUST
787 Payload of the packet: See section 2.3.22 File Transfer Payload
790 28 SILC_PACKET_RESUME_CLIENT
792 This packet is used to resume a client back to the network
793 after it has been detached. A client is able to detach from
794 the network but the client is still valid client in the network.
795 The client may then later resume its session back by sending
796 this packet to a server. Routers also use this packet to notify
797 other routers in the network that the detached client has resumed.
799 This packet MUST NOT be sent as list and the List flag MUST
802 Payload of the packet: See section 2.3.23 Resume Client Payload
807 Currently undefined commands.
812 These packet types are reserved for private use and they will
813 not be defined by this document.
818 This type is reserved for future extensions and currently it
824 2.3.1 SILC Packet Payloads
826 All payloads resides in the main data area of the SILC packet. However
827 all payloads MUST be at the start of the data area after the SILC
828 packet header and padding. All fields in the packet payload are always
829 encrypted, as they reside in the data area of the packet which is
832 Payloads described in this section are common payloads that MUST be
833 accepted anytime during SILC session. Most of the payloads may only
834 be sent with specific packet type which is defined in the description
837 There are a lot of other payloads in the SILC as well. However, they
838 are not common in the sense that they could be sent at any time.
839 These payloads are not described in this section. These are payloads
840 such as SILC Key Exchange payloads and so on. These are described
841 in [SILC1], [SILC3] and [SILC4].
845 2.3.2 Generic payloads
847 This section describes generic payloads that are not associated to any
848 specific packet type. They can be used for example inside some other
855 This payload can be used to send an ID. ID's are variable in length
856 thus this payload provides a way to send variable length ID's.
858 The following diagram represents the ID Payload.
868 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
869 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
870 | ID Type | ID Length |
871 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
875 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
883 o ID Type (2 bytes) - Indicates the type of the ID. See
884 section 2.4 SILC ID Types for list of defined ID types.
886 o ID Length (2 bytes) - Length of the ID Data area not
887 including the length of any other fields in the payload.
889 o ID Data (variable length) - The actual ID data.
894 2.3.2.2 Argument Payload
896 Argument Payload is used to set arguments for any packet payload that
897 needs and supports arguments, such as commands. Number of arguments
898 associated with a packet MUST be indicated by the packet payload which
899 needs the arguments. Argument Payloads MUST always reside right after
900 the packet payload needing the arguments. Incorrect amount of argument
901 payloads MUST cause rejection of the packet.
903 The following diagram represents the Argument Payload.
908 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
909 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
910 | Payload Length | Argument Type | |
911 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
915 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
919 Figure 4: Argument Payload
923 o Payload Length (2 bytes) - Length of the argument payload data
924 area not including the length of any other fields in the
927 o Argument Type (1 byte) - Indicates the type of the argument.
928 Every argument may have a specific type that MUST be defined
929 by the packet payload needing the argument. For example
930 every command specify a number for each argument that maybe
931 associated with the command. By using this number the receiver
932 of the packet knows what type of argument this is. If there is
933 no specific argument type this field is set to zero (0).
935 o Argument Data (variable length) - Argument data.
940 2.3.2.3 Channel Payload
942 Generic Channel Payload may be used to send information about channel,
943 its name, the Channel ID and a mode.
945 The following diagram represents the Channel Payload.
950 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
951 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
952 | Channel Name Length | |
953 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
957 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
958 | Channel ID Length | |
959 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
963 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
965 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
969 Figure 5: New Channel Payload
973 o Channel Name Length (2 bytes) - Length of the channel name
976 o Channel Name (variable length) - The name of the channel.
978 o Channel ID Length (2 bytes) - Length of the Channel ID field.
980 o Channel ID (variable length) - The Channel ID.
982 o Mode Mask (4 bytes) - A mode. This can be the mode of the
983 channel but it can also be the mode of the client on the
984 channel. The contents of this field is dependent of the
985 usage of this payload. The usage is defined separately
986 when this payload is used. This is a 32 bit MSB first value.
991 2.3.2.4 Public Key Payload
993 Generic Public Key Payload may be used to send different types of
994 public keys and certificates.
996 The following diagram represents the Public Key Payload.
1005 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
1006 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1007 | Public Key Length | Public Key Type |
1008 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1010 ~ Public Key (or certificate) ~
1012 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1016 Figure 6: Public Key Payload
1020 o Public Key Length (2 bytes) - The length of the Public Key
1021 (or certificate) field, not including any other field.
1023 o Public Key Type (2 bytes) - The public key (or certificate)
1024 type. This field indicates the type of the public key in
1025 the packet. See the [SILC3] for defined public key types.
1027 o Public Key (or certificate) (variable length) - The
1028 public key or certificate.
1033 2.3.3 Disconnect Payload
1035 Disconnect payload is sent upon disconnection. The payload is simple;
1036 reason of disconnection is sent to the disconnected party.
1038 The payload may only be sent with SILC_PACKET_DISCONNECT packet. It
1039 MUST NOT be sent in any other packet type. The following diagram
1040 represents the Disconnect Payload.
1046 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
1047 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1051 ~ Disconnect Message ~
1053 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1057 Figure 7: Disconnect Payload
1060 o Status (1 byte) - Indicates the Status Type, defined in [SILC3]
1061 for the reason of disconnection.
1063 o Disconnect Message (variable length) - Human readable UTF-8
1064 encoded string indicating reason of the disconnection. This
1070 2.3.4 Success Payload
1072 Success payload is sent when some protocol execution is successfully
1073 completed. The payload is simple; indication of the success is sent.
1074 This may be any data, including binary or human readable data.
1079 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
1080 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1082 ~ Success Indication ~
1084 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1088 Figure 8: Success Payload
1092 o Success Indication (variable length) - Indication of
1093 the success. This may be for example some flag that
1094 indicates the protocol and the success status or human
1095 readable success message. The true length of this
1096 payload is available by calculating it from the SILC
1103 2.3.5 Failure Payload
1105 This is opposite of Success Payload. Indication of failure of
1106 some protocol is sent in the payload.
1112 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
1113 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1115 ~ Failure Indication ~
1117 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1121 Figure 9: Failure Payload
1125 o Failure Indication (variable length) - Indication of
1126 the failure. This may be for example some flag that
1127 indicates the protocol and the failure status or human
1128 readable failure message. The true length of this
1129 payload is available by calculating it from the SILC
1135 2.3.6 Reject Payload
1137 This payload is sent when some protocol is rejected to be executed.
1138 Other operations MAY send this as well that was rejected. The
1139 indication of the rejection is sent in the payload. The indication
1140 may be binary or human readable data.
1146 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
1147 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1149 ~ Reject Indication ~
1151 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1155 Figure 10: Reject Payload
1159 o Reject Indication (variable length) - Indication of
1160 the rejection. This maybe for example some flag that
1161 indicates the protocol and the rejection status or human
1162 readable rejection message. The true length of this
1163 payload is available by calculating it from the SILC
1169 2.3.7 Notify Payload
1171 Notify payload is used to send notify messages. The payload is usually
1172 sent from server to client, however, server MAY send it to another
1173 server as well. This payload MAY also be sent to a channel. Client
1174 MUST NOT send this payload. The receiver of this payload MAY ignore
1175 the contents of the payload, however, notify message SHOULD be audited.
1177 The payload may only be sent with SILC_PACKET_NOTIFY packet. It MUST
1178 not be sent in any other packet type. The following diagram represents
1187 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
1188 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1189 | Notify Type | Payload Length |
1190 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1196 Figure 11: Notify Payload
1200 o Notify Type (2 bytes) - Indicates the type of the notify
1203 o Payload Length (2 bytes) - Length of the entire Notify Payload
1204 including any associated Argument Payloads.
1206 o Argument Nums (1 byte) - Indicates the number of Argument
1207 Payloads associated to this payload. Notify types may define
1208 arguments to be send along the notify message.
1211 The following list of currently defined notify types. The format for
1212 notify arguments is same as in SILC commands described in [SILC4].
1213 Note that all ID's sent in arguments are sent inside ID Payload. Also
1214 note that all passphrases that may be sent inside arguments MUST be
1215 UTF-8 [RFC2279] encoded. Also note that all public keys or certificates
1216 sent in arguments are actually Public Key Payloads.
1220 0 SILC_NOTIFY_TYPE_NONE
1222 If no specific notify type apply for the notify message this type
1226 Arguments: (1) <message>
1228 The <message> is implementation specific free text string.
1229 Receiver MAY ignore this message.
1232 1 SILC_NOTIFY_TYPE_INVITE
1234 Sent when an client is invited to a channel. This is also sent
1235 when the invite list of the channel is changed. This notify type
1236 is sent between routers and if an client was invited, to the
1237 client as well. In this case the packet is destined to the client.
1240 Arguments: (1) <Channel ID> (2) <channel name>
1241 (3) [<sender Client ID>] (4) [<adding client>]
1242 (5) [<removing client>]
1244 The <Channel ID> is the channel. The <channel name> is the name
1245 of the channel and is provided because the client which receives
1246 this notify packet may not have a way to resolve the name of the
1247 channel from the <Channel ID>. The <sender Client ID> is the
1248 Client ID which invited the client to the channel. The <adding
1249 client> and the <removing client> indicates the added or removed
1250 client from the channel's invite list. The format of the <adding
1251 client> and the <removing client> is defined in the [SILC4] with
1252 SILC_COMMAND_INVITE command.
1254 The <adding client> and <removing client> MUST NOT be sent when
1255 the packet is destined to a client.
1258 2 SILC_NOTIFY_TYPE_JOIN
1260 Sent when client has joined to a channel. The server MUST
1261 distribute this type only to the local clients on the channel
1262 and then send it to its primary router. The router or server
1263 receiving the packet distributes this type to the local clients
1264 on the channel and broadcast it to the network.
1267 Arguments: (1) [<Client ID>] (2) <Channel ID>
1269 The <Client ID> is the client that joined to the channel indicated
1270 by the <Channel ID>.
1273 3 SILC_NOTIFY_TYPE_LEAVE
1275 Sent when client has left a channel. The server must distribute
1276 this type only to the local clients on the channel and then send
1277 it to its primary router. The router or server receiving the
1278 packet distributes this type to the local clients on the channel
1279 and broadcast it to the network.
1282 Arguments: (1) <Client ID>
1284 The <Client ID> is the client which left the channel.
1287 4 SILC_NOTIFY_TYPE_SIGNOFF
1289 Sent when client signoff from SILC network. The server MUST
1290 distribute this type only to the local clients on the channel and
1291 then send it to its primary router. The router or server receiving
1292 the packet distributes this type to the local clients on the
1293 channel and broadcast it to the network.
1296 Arguments: (1) <Client ID> (2) <message>
1298 The <Client ID> is the client which left SILC network. The
1299 <message> is free text string indicating the reason of the signoff.
1302 5 SILC_NOTIFY_TYPE_TOPIC_SET
1304 Sent when topic is set/changed on a channel. This type must be
1305 sent only to the clients which is joined on the channel which
1306 topic was set or changed.
1309 Arguments: (1) <ID Payload> (2) <topic>
1311 The <ID Payload> is the ID of the entity who set the topic. It
1312 usually is Client ID but it can be Server ID and Channel ID as well.
1317 6 SILC_NOTIFY_TYPE_NICK_CHANGE
1319 Sent when client changes nick on a channel. The server MUST
1320 distribute this type only to the local clients on the channel
1321 and then send it to its primary router. The router or server
1322 receiving the packet distributes this type to the local clients
1323 on the channel and broadcast it to the network.
1326 Arguments: (1) <Old Client ID> (2) <New Client ID>
1329 The <Old Client ID> is the old ID of the client which changed
1330 the nickname. The <New Client ID> is the new ID generated by
1331 the change of the nickname. The <nickname> is the new nickname.
1332 Note that it is possible to send this notify even if the nickname
1333 has not changed, but client ID has changed.
1336 7 SILC_NOTIFY_TYPE_CMODE_CHANGE
1338 Sent when channel mode has changed. This type MUST be sent only
1339 to the clients which is joined on the channel which mode was
1343 Arguments: (1) <ID Payload> (2) <mode mask>
1344 (3) [<cipher>] (4) <[hmac>]
1345 (5) [<passphrase>] (6) [<founder public key>]
1347 The <ID Payload> is the ID (usually Client ID but it can be
1348 Server ID as well when the router is enforcing channel mode
1349 change) of the entity which changed the mode. The <mode mask>
1350 is the new mode mask of the channel. The client can safely
1351 ignore the <cipher> argument since the SILC_PACKET_CHANNEL_KEY
1352 packet will force the new channel key change anyway. The <hmac>
1353 argument is important since the client is responsible of setting
1354 the new HMAC and the hmac key into use. The <passphrase> is
1355 the passphrase of the channel, if it was now set. The <founder
1356 public key> argument is sent when the founder mode on the
1357 channel was set. All routers and servers that receive the packet
1358 MUST save the founder's public key so that the founder can
1359 reclaim the channel founder rights back for the channel on any
1360 server in the network.
1365 8 SILC_NOTIFY_TYPE_CUMODE_CHANGE
1367 Sent when user mode on channel has changed. This type MUST be
1368 sent only to the clients which is joined on the channel where
1369 the target client is on.
1372 Arguments: (1) <ID Payload> (2) <mode mask>
1373 (3) <Target Client ID> (3) [<founder pubkey>]
1375 The <ID Payload> is the ID (usually Client ID but it can be
1376 Server ID as well when the router is enforcing user's mode
1377 change) of the entity which changed the mode. The <mode mask>
1378 is the new mode mask of the channel. The <Target Client ID>
1379 is the client which mode was changed. The <founder pubkey>
1380 is the public key of the channel founder and is sent only
1381 when first setting the channel founder mode using the
1382 SILC_COMMAND_CUMODE command, and when sending this notify.
1385 9 SILC_NOTIFY_TYPE_MOTD
1387 Sent when Message of the Day (motd) is sent to a client.
1390 Arguments: (1) <motd>
1392 The <motd> is the Message of the Day.
1395 10 SILC_NOTIFY_TYPE_CHANNEL_CHANGE
1397 Sent when channel's ID has changed for a reason or another.
1398 This is sent by normal server to the client. This can also be
1399 sent by router to other server to force the Channel ID change.
1400 The Channel ID MUST be changed to use the new one. When sent
1401 to clients, this type MUST be sent only to the clients which is
1402 joined on the channel.
1405 Arguments: (1) <Old Channel ID> (2) <New Channel ID>
1407 The <Old Channel ID> is the channel's old ID and the <New
1408 Channel ID> is the new one that MUST replace the old one.
1409 Server which receives this from router MUST re-announce the
1410 channel to the router by sending SILC_PACKET_NEW_CHANNEL packet
1411 with the new Channel ID.
1414 11 SILC_NOTIFY_TYPE_SERVER_SIGNOFF
1416 Sent when server quits SILC network. Those clients from this
1417 server that are on channels must be removed from the channel.
1420 Arguments: (1) <Server ID> (n) [<Client ID>] [...]
1422 The <Server ID> is the server's ID. The rest of the arguments
1423 are the Client ID's of the client's which are coming from this
1424 server and are thus quitting the SILC network also. If the
1425 maximum number of arguments are reached another
1426 SILC_NOTIFY_TYPE_SERVER_SIGNOFF notify packet MUST be sent.
1427 When this notify packet is sent between routers the Client ID's
1428 MAY be omitted. Server receiving the Client ID's in the payload
1429 may use them directly to remove the client.
1432 12 SILC_NOTIFY_TYPE_KICKED
1434 Sent when a client has been kicked from a channel. This is
1435 sent also to the client which was kicked from the channel.
1436 The client which was kicked from the channel MUST be removed
1437 from the channel. This notify type is always destined to the
1438 channel. The router or server receiving the packet distributes
1439 this type to the local clients on the channel and broadcast it
1443 Arguments: (1) <Client ID> (2) [<comment>]
1444 (3) <Kicker's Client ID>
1446 The <Client ID> is the client which was kicked from the channel.
1447 The kicker may have set the <comment> to indicate the reason for
1448 the kicking. The <Kicker's Client ID> is the kicker.
1451 13 SILC_NOTIFY_TYPE_KILLED
1453 Sent when a client has been killed from the network. This is sent
1454 also to the client which was killed from the network. The client
1455 which was killed from the network MUST be removed from the network.
1456 This notify type is destined directly to the client which was
1457 killed and to channel if the client is on any channel. The router
1458 or server receiving the packet distributes this type to the local
1459 clients on the channel and broadcast it to the network.
1462 Arguments: (1) <Client ID> (2) [<comment>]
1465 The <Client ID> is the client which was killed from the network.
1466 The killer may have set the <comment> to indicate the reason for
1467 the killing. The <Killer's ID> is the killer, which may be
1468 client but also router server.
1471 14 SILC_NOTIFY_TYPE_UMODE_CHANGE
1473 Sent when user's mode in the SILC changes. This type is sent
1474 only between routers as broadcast packet.
1477 Arguments: (1) <Client ID> (2) <mode mask>
1479 The <Client ID> is the client which mode was changed. The
1480 <mode mask> is the new mode mask.
1483 15 SILC_NOTIFY_TYPE_BAN
1485 Sent when the ban list of the channel is changed. This type is
1486 sent only between routers as broadcast packet.
1489 Arguments: (1) <Channel ID> (2) [<adding client>]
1490 (3) [<removing client>]
1492 The <Channel ID> is the channel which ban list was changed. The
1493 <adding client> is used to indicate that a ban was added and the
1494 <removing client> is used to indicate that a ban was removed from
1495 the ban list. The format of the <adding client> and the
1496 <removing client> is defined in the [SILC4] with SILC_COMMAND_BAN
1500 16 SILC_NOTIFY_TYPE_ERROR
1502 Sent when an error occurs during processing some SILC procedure.
1503 This is not used when error occurs during command processing, see
1504 [SILC3] for more information about commands and command replies.
1505 This type is sent directly to the sender of the packet whose packet
1506 caused the error. See [SILC1] for definition when this type
1510 Arguments: (1) <Status Type> (n) [...]
1512 The <Status Type> is the error type defined in [SILC3]. Note that
1513 same types are also used with command replies to indicate the
1514 status of a command. Both commands and this notify type share
1515 same status types. Rest of the arguments are status type
1516 dependent and are specified with those status types that can be
1517 sent currently inside this notify type in [SILC3]. The <Status
1518 Type> is of size of 1 byte.
1521 17 SILC_NOTIFY_TYPE_WATCH
1523 Sent to indicate change in a watched user. Client can set
1524 nicknames to be watched with SILC_COMMAND_WATCH command, and
1525 receive notifications when they login to network, signoff from
1526 the network or their user mode is changed. This notify type
1527 is used to deliver these notifications. The notify type is
1528 sent directly to the watching client.
1531 Arguments: (1) <Client ID> (2) [<nickname>]
1532 (3) <user mode> (4) [<Notify Type>]
1534 The <Client ID> is the user's Client ID which is being watched,
1535 and the <nickname> is its nickname. If the client just
1536 changed the nickname, then <nickname> is the new nickname, but
1537 the <Client ID> is the old client ID. The <user mode> is the
1538 user's current user mode. The <Notify Type> can be same as the
1539 Notify Payload's Notify Type, and is 16 bit MSB first order value.
1540 If provided it may indicate the notify that occurred for the
1541 client. If client logged in to the network the <Notify Type>
1542 MUST NOT be present.
1545 Notify types starting from 16384 are reserved for private notify
1548 Router server which receives SILC_NOTIFY_TYPE_SIGNOFF,
1549 SILC_NOTIFY_TYPE_SERVER_SIGNOFF, SILC_NOTIFY_TYPE_KILLED,
1550 SILC_NOTIFY_TYPE_NICK_CHANGE and SILC_NOTIFY_TYPE_UMODE_CHANGE
1551 MUST check whether someone in the local cell is watching the nickname
1552 the client has, and send the SILC_NOTIFY_TYPE_WATCH notify to the
1553 watcher, unless the client in case has the SILC_UMODE_REJECT_WATCHING
1554 user mode set. If the watcher client and the client that was
1555 watched is same the notify SHOULD NOT be sent.
1563 Error payload is sent upon error. Error may occur in various
1564 conditions when server sends this packet. Client MUST NOT send this
1565 payload but MUST be able to accept it. However, client MAY
1566 totally ignore the contents of the packet as server is going to
1567 take action on the error anyway. However, it is recommended
1568 that the client takes error packet seriously.
1574 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
1575 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1579 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1583 Figure 12: Error Payload
1587 o Error Message (variable length) - Human readable error
1593 2.3.9 Channel Message Payload
1595 Channel Message Payload is used to send message to channels, a group
1596 of users. These messages can only be sent if client has joined to
1597 some channel. Even though this packet is very common in SILC it
1598 is still special packet. Some special handling on sending and
1599 reception of channel message is required.
1601 Padding MUST be applied into this payload since the payload is
1602 encrypted separately from other parts of the packet with the
1603 channel specific key. Hence the requirement of the padding.
1604 The padding SHOULD be random data. The packet MUST be made
1605 multiple by eight (8) or by the block size of the cipher, which
1608 The SILC header in this packet is encrypted with the session key
1609 of the next receiver of the packet. Nothing else is encrypted
1610 with that key. Thus, the actual packet and padding to be
1611 encrypted with the session key is SILC Header plus padding to it
1612 to make it multiple by eight (8) or multiple by the block size
1613 of the cipher, which ever is larger.
1615 Receiver of the the channel message packet is able to determine
1616 the channel the message is destined to by checking the destination
1617 ID from the SILC Packet header which tells the destination channel.
1618 The original sender of the packet is also determined by checking
1619 the source ID from the header which tells the client which sent
1622 The payload may only be sent with SILC_PACKET_CHANNEL_MESSAGE packet.
1623 It MUST NOT be sent in any other packet type. The following diagram
1624 represents the Channel Message Payload.
1626 (*) indicates that the field is not encrypted.
1632 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
1633 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1634 | Message Flags | Message Length |
1635 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1639 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1640 | Padding Length | |
1641 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1645 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1647 ~ Initial Vector * ~
1649 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1653 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1657 Figure 13: Channel Message Payload
1661 o Message Flags (2 bytes) - Includes the Message Flags of
1662 the channel messages. The flags can indicate a reason or
1663 purpose for the channel message. Note that the Private
1664 Message Payload use these same Message Flags for the same
1665 purpose. The following Message Flags are defined:
1667 0x0000 SILC_MESSAGE_FLAG_NONE
1669 No specific flags set.
1671 0x0001 SILC_MESSAGE_FLAG_AUTOREPLY
1673 This message is an automatic reply to an earlier
1676 0x0002 SILC_MESSAGE_FLAG_NOREPLY
1678 There should not be reply messages to this
1681 0x0004 SILC_MESSAGE_FLAG_ACTION
1683 The sender is performing an action and the message
1684 is the indication of the action.
1686 0x0008 SILC_MESSAGE_FLAG_NOTICE
1688 The message is for example an informational notice
1691 0x0010 SILC_MESSAGE_FLAG_REQUEST
1693 This is a generic request flag to send request
1694 messages. A separate document should define any
1695 payloads associated to this flag.
1697 0x0020 SILC_MESSAGE_FLAG_SIGNED
1699 This flag indicates that the message is signed
1700 with sender's private key and thus can be verified
1701 by the receiver using the sender's public key. A
1702 separate document should define the detailed procedure
1703 of the signing process and any associated payloads
1706 0x0040 SILC_MESSAGE_FLAG_REPLY
1708 This is a generic reply flag to send a reply to
1709 previously received request. A separate document
1710 should define any payloads associated to this flag.
1712 0x0080 SILC_MESSAGE_FLAG_DATA
1714 This is a generic data flag, indicating that the
1715 message includes some data which can be interpreted
1716 in a specific way. Using this flag any kind of data
1717 can be delivered inside message payload. A separate
1718 document should define how this flag is interpreted
1719 and define any associated payloads.
1721 0x0100 SILC_MESSAGE_FLAG_UTF8
1723 This flag indicates that the message is UTF-8 encoded
1724 textual message. When sending text messages this
1725 flag SHOULD be used. When this flag is used the text
1726 sent as message MUST be UTF-8 encoded.
1728 0x0200 - 0x0800 RESERVED
1730 Reserved for future flags
1732 0x1000 - 0x8000 PRIVATE RANGE
1734 Private range for free use.
1736 o Message Length (2 bytes) - Indicates the length of the
1737 Message Data field in the payload, not including any
1740 o Message Data (variable length) - The actual message to
1743 o Padding Length (2 bytes) - Indicates the length of the
1744 Padding field in the payload, not including any other
1747 o Padding (variable length) - The padding that MUST be
1748 applied because this payload is encrypted separately from
1749 other parts of the packet.
1751 o Initial Vector (variable length) - The initial vector
1752 that has been used in packet encryption. It needs to be
1753 used in the packet decryption as well. Contents of this
1754 field depends on the encryption algorithm and mode. This
1755 field is not encrypted, is not included in padding
1756 calculation and its length equals to cipher's block size.
1757 This field is authenticated by the channel message MAC.
1759 o MAC (variable length) - The MAC computed from the
1760 Message Flags, Message Length, Message Data, Padding Length,
1761 Padding and Initial Vector fields in that order. The MAC
1762 is computed after the payload is encrypted. This is so
1763 called Encrypt-Then-MAC order; first encrypt, then compute
1764 MAC from ciphertext. The MAC protects the integrity of
1765 the channel message. Also, if more than one private key
1766 has been set for the channel, the receiver can verify which
1767 of the keys must be used in decryption. This field is not
1773 2.3.10 Channel Key Payload
1775 All traffic in channels are protected by channel specific keys.
1776 Channel Key Payload is used to distribute channel keys to all
1777 clients on the particular channel. Channel keys are sent when
1778 the channel is created, when new user joins to the channel and
1779 whenever a user has left a channel. Server creates the new
1780 channel key and distributes it to the clients by encrypting this
1781 payload with the session key shared between the server and
1782 the client. After that, client starts using the key received
1783 in this payload to protect the traffic on the channel.
1785 The client which is joining to the channel receives its key in the
1786 SILC_COMMAND_JOIN command reply message thus it is not necessary to
1787 send this payload to the entity which sent the SILC_COMMAND_JOIN
1790 Channel keys are cell specific thus every router in the cell have
1791 to create a channel key and distribute it if any client in the
1792 cell has joined to a channel. Channel traffic between cell's
1793 are not encrypted using channel keys, they are encrypted using
1794 normal session keys between two routers. Inside a cell, all
1795 channel traffic is encrypted with the specified channel key.
1796 Channel key should expire periodically, say, in one hour, in
1797 which case new channel key is created and distributed.
1799 The payload may only be sent with SILC_PACKET_CHANNEL_KEY packet.
1800 It MUST NOT be sent in any other packet type. The following diagram
1801 represents the Channel Key Payload.
1807 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
1808 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1809 | Channel ID Length | |
1810 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1814 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1815 | Cipher Name Length | |
1816 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1820 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1821 | Channel Key Length | |
1822 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1826 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1830 Figure 14: Channel Key Payload
1835 o Channel ID Length (2 bytes) - Indicates the length of the
1836 Channel ID field in the payload, not including any other
1839 o Channel ID (variable length) - The Channel ID of the
1840 channel this key is meant for.
1842 o Cipher Name Length (2 bytes) - Indicates the length of the
1843 Cipher name field in the payload, not including any other
1846 o Cipher Name (variable length) - Name of the cipher used
1847 in the protection of channel traffic. This name is
1848 initially decided by the creator of the channel but it
1849 MAY change during the life time of the channel as well.
1851 o Channel Key Length (2 bytes) - Indicates the length of the
1852 Channel Key field in the payload, not including any other
1855 o Channel Key (variable length) - The actual channel key
1861 2.3.11 Private Message Payload
1863 Private Message Payload is used to send private message between
1864 two clients (or users for that matter). The messages are sent only
1865 to the specified user and no other user inside SILC network is
1866 able to see the message. The message is protected by the session
1867 key established by the SILC Key Exchange Protocol.
1869 However, it is also possible to agree to use a private key to
1870 protect just the private messages. It is for example possible to
1871 perform Key Agreement between two clients. See section 2.3.20
1872 Key Agreement Payload how to perform key agreement. See also
1873 section 2.3.12 Private Message Key Payload for another way of
1874 using private keys with private messages. See [SILC1] section
1875 4.6 for detailed description for private message key generation
1878 If normal session key is used to protect the message, every server
1879 between the sender client and the receiving client MUST decrypt the
1880 packet and always re-encrypt it with the session key of the next
1881 receiver of the packet. See section Client To Client in [SILC1].
1883 When private key is used to protect the message, servers between
1884 the sender and the receiver needs not to decrypt/re-encrypt the
1885 packet. Section Client To Client in [SILC1] gives example of this
1888 The payload may only be sent with SILC_PACKET_PRIVATE_MESSAGE
1889 packet. It MUST NOT be sent in any other packet type. The following
1890 diagram represents the Private Message Payload.
1892 (*) indicates that the field is not encrypted.
1898 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
1899 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1900 | Message Flags | Message Data Length |
1901 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1905 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1909 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1913 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1917 Figure 15: Private Message Payload
1921 o Message Flags (2 bytes) - This field includes the Message
1922 Flags of the private message. They can indicate a different
1923 reason or purpose for the private message. See the section
1924 2.3.9 Channel Message Payload for defined flags. Note that
1925 the Channel Message Payload use the same flags for the
1928 o Message Data Length (2 bytes) - Indicates the length of the
1929 Message Data field, not including any other field.
1931 o Message Data (variable length) - The actual message to
1934 o Padding (variable length) - This field is present only
1935 when the private message payload is encrypted with private
1936 message key. In this case the padding is applied to make
1937 the payload multiple by eight (8), or by the block size of
1938 the cipher, which ever is larger. When encrypted with
1939 normal session keys, this field MUST NOT be included.
1941 o MAC (variable length) - This field is present only when
1942 the private message payload is encrypted with private
1943 message key. The MAC is computed from the Message Flags,
1944 Message Data Length, Message Data and Padding fields in
1945 that order. The MAC protects the integrity of the private
1946 message. The MAC is computed after encryption from the
1947 ciphertext. This is so called Encrypt-Then-MAC order;
1948 first encrypt, then compute MAC from ciphertext. Note that,
1949 this field is not encrypted and thus not included in the
1950 padding calculation. When encrypted with normal session
1951 keys, this field MUST NOT be included.
1956 2.3.12 Private Message Key Payload
1958 This payload is optional and can be used to send private message
1959 key between two clients in the network. The packet is secured with
1960 normal session keys. By default private messages are encrypted
1961 with session keys, and with this payload it is possible to set
1962 private key for private message encryption between two clients.
1964 The receiver of this payload SHOULD verify for example from user
1965 whether user wants to receive private message key. Note that there
1966 are other, more secure ways of exchanging private message keys in
1967 the SILC network. Instead of sending this payload it is possible to
1968 negotiate the private message key with SKE protocol using the Key
1969 Agreement payload directly peer to peer, see section 2.3.20.
1971 This payload may only be sent by client to another client. Server
1972 MUST NOT send this payload at any time. After sending this payload
1973 the sender of private messages must set the Private Message Key
1974 flag into SILC Packet Header.
1976 The payload may only be sent with SILC_PACKET_PRIVATE_MESSAGE_KEY
1977 packet. It MUST NOT be sent in any other packet type. The following
1978 diagram represents the Private Message Key Payload.
1984 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
1985 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1986 | Private Message Key Length | |
1987 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1989 ~ Private Message Key ~
1991 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1992 | Cipher Name Length | |
1993 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1997 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1998 | HMAC Name Length | |
1999 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2003 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2007 Figure 16: Private Message Key Payload
2013 o Private Message Key Length (2 bytes) - Indicates the length
2014 of the Private Message Key field in the payload, not including
2017 o Private Message Key (variable length) - The actual private
2018 message key material.
2020 o Cipher Name Length (2 bytes) - Indicates the length of the
2021 Cipher Name field in the payload, not including any other
2024 o Cipher Name (variable length) - Name of the cipher to use
2025 in the private message encryption. If this field does not
2026 exist then the default cipher of the SILC protocol is used.
2027 See the [SILC1] for defined ciphers.
2029 o HMAC Name Length (2 bytes) - Indicates the length of the
2030 HMAC Name field in the payload, not including any other
2033 o HMAC Name (variable length) - Name of the HMAC to use
2034 in the private message MAC computation. If this field does
2035 not exist then the default HMAC of the SILC protocol is used.
2036 See the [SILC1] for defined HMACs.
2041 2.3.13 Command Payload
2043 Command Payload is used to send SILC commands from client to server.
2044 Also server MAY send commands to other servers. The following diagram
2045 represents the Command Payload.
2051 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
2052 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2053 | Payload Length | SILC Command | Arguments Num |
2054 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2055 | Command Identifier |
2056 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2060 Figure 17: Command Payload
2064 o Payload Length (2 bytes) - Length of the entire command
2065 payload including any command argument payloads associated
2068 o SILC Command (1 byte) - Indicates the SILC command. This MUST
2069 be set to non-zero value. If zero (0) value is found in this
2070 field the packet MUST be discarded.
2072 o Arguments Num (1 byte) - Indicates the number of arguments
2073 associated with the command. If there are no arguments this
2074 field is set to zero (0). The arguments MUST follow the
2075 command payload. See section 2.3.2.2 for definition of the
2078 o Command Identifier (2 bytes) - Identifies this command at the
2079 sender's end. The entity which replies to this command MUST
2080 set the value found from this field into the Command Payload
2081 used to send the reply to the sender. This way the sender
2082 can identify which command reply belongs to which originally
2083 sent command. What this field includes is implementation
2084 issue but it is RECOMMENDED that wrapping counter value is
2085 used in the field. Value zero (0) in this field means that
2086 no specific value is set.
2089 See [SILC4] for detailed description of different SILC commands,
2090 their arguments and their reply messages.
2096 2.3.14 Command Reply Payload
2098 Command Reply Payload is used to send replies to the commands. The
2099 Command Reply Payload is identical to the Command Payload thus see
2100 the upper section for the Command Payload specification.
2102 The entity which sends the reply packet MUST set the Command Identifier
2103 field in the reply packet's Command Payload to the value it received
2104 in the original command packet.
2106 See SILC Commands in [SILC4] for detailed description of different
2107 SILC commands, their arguments and their reply messages.
2111 2.3.15 Connection Auth Request Payload
2113 Client MAY send this payload to server to request the authentication
2114 method that must be used in authentication protocol. If client knows
2115 this information beforehand this payload is not necessary to be sent.
2116 Server performing authentication with another server MAY also send
2117 this payload to request the authentication method. If the connecting
2118 server already knows this information this payload is not necessary
2121 Server receiving this request MUST reply with same payload sending
2122 the mandatory authentication method. Algorithms that may be required
2123 to be used by the authentication method are the ones already
2124 established by the SILC Key Exchange protocol. See section Key
2125 Exchange Start Payload in [SILC3] for detailed information.
2127 The payload may only be sent with SILC_PACKET_CONNECTION_AUTH_REQUEST
2128 packet. It MUST NOT be sent in any other packet type. The following
2129 diagram represents the Connection Auth Request Payload.
2135 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
2136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2137 | Connection Type | Authentication Method |
2138 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2142 Figure 18: Connection Auth Request Payload
2146 o Connection Type (2 bytes) - Indicates the type of the
2147 connection. The following connection types are defined:
2154 If any other type is found in this field the packet MUST be
2155 discarded and the authentication MUST be failed.
2157 o Authentication Method (2 bytes) - Indicates the authentication
2158 method to be used in the authentication protocol. The following
2159 authentication methods are defined:
2162 1 password (mandatory)
2163 2 public key (mandatory)
2165 If any other type is found in this field the packet MUST be
2166 discarded and the authentication MUST be failed. If this
2167 payload is sent as request to receive the mandatory
2168 authentication method this field MUST be set to zero (0),
2169 indicating that receiver should send the mandatory
2170 authentication method. The receiver sending this payload
2171 to the requesting party, MAY also set this field to zero (0)
2172 to indicate that authentication is not required. In this
2173 case authentication protocol still MUST be started but
2174 server is most likely to respond with SILC_PACKET_SUCCESS
2182 2.3.16 New ID Payload
2184 New ID Payload is a multipurpose payload. It is used to send newly
2185 created ID's from clients and servers. When client connects to server
2186 and registers itself to the server by sending SILC_PACKET_NEW_CLIENT
2187 packet, server replies with this packet by sending the created ID for
2188 the client. Server always creates the ID for the client.
2190 This payload is also used when server tells its router that new client
2191 has registered to the SILC network. In this case the server sends
2192 the Client ID of the client to the router. Similarly when router
2193 distributes information to other routers about the client in the SILC
2194 network this payload is used.
2196 Also, when server connects to router, router uses this payload to inform
2197 other routers about new server in the SILC network. However, every
2198 server (or router) creates their own ID's thus the ID distributed by
2199 this payload is not created by the distributor in this case. Servers
2200 create their own ID's. Server registers itself to the network by
2201 sending SILC_PACKET_NEW_SERVER to the router it connected to. The case
2202 is same when router connects to another router.
2204 However, this payload MUST NOT be used to send information about new
2205 channels. New channels are always distributed by sending the dedicated
2206 SILC_PACKET_NEW_CHANNEL packet.
2208 Thus, this payload is very important and used every time when some
2209 new entity is registered to the SILC network. Client MUST NOT send this
2210 payload. Both client and server (and router) MAY receive this payload.
2212 The packet uses generic ID Payload as New ID Payload. See section
2213 2.3.2.1 for generic ID Payload.
2217 2.3.17 New Client Payload
2219 When client is connected to the server, keys has been exchanged and
2220 connection has been authenticated client MUST register itself to the
2221 server. Client's first packet after key exchange and authentication
2222 protocols must be SILC_PACKET_NEW_CLIENT. This payload tells server all
2223 the relevant information about the connected user. Server creates a new
2224 client ID for the client when received this payload and sends it to the
2225 client in New ID Payload.
2227 This payload sends username and real name of the user on the remote host
2228 which is connected to the SILC server with SILC client. The server
2229 creates the client ID according the information sent in this payload.
2230 The nickname of the user becomes the username sent in this payload.
2231 However, client should call NICK command after sending this payload to
2232 set the real nickname of the user which is then used to create new
2235 The payload may only be sent with SILC_PACKET_NEW_CLIENT packet. It
2236 MUST NOT be sent in any other packet type. The following diagram
2237 represents the New Client Payload.
2243 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
2244 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2245 | Username Length | |
2246 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2250 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2251 | Real Name Length | |
2252 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2256 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2260 Figure 19: New Client Payload
2264 o Username Length (2 bytes) - Length of the Username field.
2266 o Username (variable length) - The username of the user on
2267 the host where connecting to the SILC server.
2269 o Real Name Length (2 bytes) - Length of the Real Name field.
2271 o Real Name (variable length) - The real name of the user
2272 on the host where connecting to the SILC server.
2277 2.3.18 New Server Payload
2279 This payload is sent by server when it has completed successfully both
2280 key exchange and connection authentication protocols. The server
2281 MUST register itself to the SILC Network by sending this payload.
2282 The first packet after these key exchange and authentication protocols
2283 is SILC_PACKET_NEW_SERVER packet. The payload includes the Server ID
2284 of the server that it has created by itself. It also includes a
2285 name of the server that is associated to the Server ID.
2287 The payload may only be sent with SILC_PACKET_NEW_SERVER packet. It
2288 MUST NOT be sent in any other packet type. The following diagram
2289 represents the New Server Payload.
2296 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
2297 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2298 | Server ID Length | |
2299 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2303 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2304 | Server Name Length | |
2305 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2309 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2313 Figure 20: New Server Payload
2317 o Server ID Length (2 bytes) - Length of the Server ID Data
2320 o Server ID Data (variable length) - The actual Server ID
2323 o Server Name Length (2 bytes) - Length of the server name
2326 o Server Name (variable length) - The server name.
2331 2.3.19 New Channel Payload
2333 Information about newly created channel is broadcasted to all routers
2334 in the SILC network by sending this packet payload. Channels are
2335 created by router of the cell. Server never creates channels unless
2336 it is a standalone server and it does not have router connection,
2337 in this case server acts as router. Normal server send JOIN command
2338 to the router (after it has received JOIN command from client) which
2339 then processes the command and creates the channel. Client MUST NOT
2340 send this packet. Server may send this packet to a router when it is
2341 announcing its existing channels to the router after it has connected
2344 The packet uses generic Channel Payload as New Channel Payload. See
2345 section 2.3.2.3 for generic Channel Payload. The Mode Mask field in the
2346 Channel Payload is the mode of the channel.
2350 2.3.20 Key Agreement Payload
2352 This payload is used by clients to request key negotiation between
2353 another client in the SILC Network. The key agreement protocol used
2354 is the SKE protocol. The result of the protocol, the secret key
2355 material, can be used for example as private message key between the
2356 two clients. This significantly adds security as the key agreement
2357 is performed outside the SILC network. The server and router MUST NOT
2360 The sender MAY tell the receiver of this payload the hostname and the
2361 port where the SKE protocol is running in the sender's end. The
2362 receiver MAY then initiate the SKE negotiation with the sender. The
2363 sender MAY also optionally not to include the hostname and the port
2364 of its SKE protocol. In this case the receiver MAY reply to the
2365 request by sending the same payload filled with the receiver's hostname
2366 and the port where the SKE protocol is running. The sender MAY then
2367 initiate the SKE negotiation with the receiver.
2369 This payload may be sent with SILC_PACKET_KEY_AGREEMENT and
2370 SILC_PACKET_FTP packet types. It MUST NOT be sent in any other packet
2371 types. The following diagram represents the Key Agreement Payload.
2377 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
2378 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2379 | Hostname Length | |
2380 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2384 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2386 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2390 Figure 21: Key Agreement Payload
2394 o Hostname Length (2 bytes) - Indicates the length of the
2397 o Hostname (variable length) - The hostname or IP address where
2398 the SKE protocol is running. The sender MAY fill this field
2399 when sending the payload. If the receiver sends this payload
2400 as reply to the request it MUST fill this field.
2402 o Port (4 bytes) - The port where the SKE protocol is bound.
2403 The sender MAY fill this field when sending the payload. If
2404 the receiver sends this payload as reply to the request it
2405 MUST fill this field. This is a 32 bit MSB first order value.
2409 After the key material has been received from the SKE protocol it is
2410 processed as the [SILC3] describes. If the key material is used as
2411 channel private key then the Sending Encryption Key, as defined in
2412 [SILC3] is used as the channel private key. Other key material must
2413 be discarded. The [SILC1] in section 4.6 defines the way to use the
2414 key material if it is intended to be used as private message keys.
2415 Any other use for the key material is undefined.
2419 2.3.21 Resume Router Payload
2421 The payload may only be sent with SILC_PACKET_RESUME_ROUTER packet. It
2422 MUST NOT be sent in any other packet type. The Following diagram
2423 represents the Resume Router Payload.
2429 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
2430 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2431 | Type | Session ID |
2432 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2436 Figure 22: Resume Router Payload
2440 o Type (1 byte) - Indicates the type of the backup resume
2441 protocol packet. The type values are defined in [SILC1].
2443 o Session ID (1 bytes) - Indicates the session ID for the
2444 backup resume protocol. The sender of the packet sets this
2445 value and the receiver MUST set the same value in subsequent
2451 2.3.22 File Transfer Payload
2453 File Transfer Payload is used to perform file transfer protocol
2454 between two entities in the network. The actual file transfer
2455 protocol is always encapsulated inside the SILC Packet. The actual
2456 data stream is also sent peer to peer outside SILC network.
2458 When an entity, usually a client wishes to perform file transfer
2459 protocol with another client in the network, they perform Key Agreement
2460 protocol as described in the section 2.3.20 Key Agreement Payload and
2461 in [SILC3], inside File Transfer Payload. After the Key Agreement
2462 protocol has been performed the subsequent packets in the data stream
2463 will be protected using the new key material. The actual file transfer
2464 protocol is also initialized in this stage. All file transfer protocol
2465 packets are always encapsulated in the File Transfer Payload and
2466 protected with the negotiated key material.
2468 The payload may only be sent with SILC_PACKET_FTP packet. It MUST NOT
2469 be sent in any other packet type. The following diagram represents the
2470 File Transfer Payload.
2475 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
2476 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2482 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2486 Figure 23: File Transfer Payload
2490 o Type (1 byte) - Indicates the type of the file transfer
2491 protocol. The following file transfer protocols has been
2494 1 SSH File Transfer Protocol (SFTP) (mandatory)
2496 If zero (0) value or any unsupported file transfer protocol
2497 type is found in this field the packet must be discarded.
2498 The currently mandatory file transfer protocol is SFTP.
2499 The SFTP protocol is defined in [SFTP].
2501 o Data (variable length) - Arbitrary file transfer data. The
2502 contents and encoding of this field is dependent of the usage
2503 of this payload and the type of the file transfer protocol.
2504 When this payload is used to perform the Key Agreement
2505 protocol, this field include the Key Agreement Payload,
2506 as defined in the section 2.3.20 Key Agreement Payload.
2507 When this payload is used to send the actual file transfer
2508 protocol data, the encoding is defined in the corresponding
2509 file transfer protocol.
2514 2.3.23 Resume Client Payload
2516 This payload is used by client to resume its detached session in the
2517 SILC Network. A client is able to detach itself from the network by
2518 sending SILC_COMMAND_DETACH command to its server. The network
2519 connection to the client is lost but the client remains as valid
2520 client in the network. The client is able to resume the session back
2521 by sending this packet and including the old Client ID, and an
2522 Authentication Payload [SILC1] which the server uses to verify with
2523 the detached client's public key. This also implies that the
2524 mandatory authentication method is public key authentication.
2526 Server or router that receives this from the client also sends this,
2527 without the Authentication Payload, to routers in the network so that
2528 they know the detached client has resumed. Refer to the [SILC1] for
2529 detailed description how the detaching and resuming procedure is
2532 The payload may only be sent with SILC_PACKET_RESUME CLIENT packet. It
2533 MUST NOT be sent in any other packet type. The following diagram
2534 represents the Resume Client Payload.
2539 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
2540 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2541 | Client ID Length | |
2542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2546 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2548 ~ Authentication Payload ~
2550 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2554 Figure 24: Resume Client Payload
2558 o Client ID Length (1 byte) - The length of the Client ID
2559 field not including any other field.
2561 o Client ID (variable length) - The detached client's Client
2562 ID. The client that sends this payload must know the Client
2565 o Authentication Payload (variable length) - The authentication
2566 payload that the server will verify with the detached client's
2567 public key. If the server doesn't know the public key, it must
2568 retrieve it for example with SILC_COMMAND_GETKEY command.
2576 ID's are extensively used in the SILC network to associate different
2577 entities. The following ID's has been defined to be used in the SILC
2583 When ever specific ID cannot be used this is used.
2587 Server ID to associate servers. See the format of
2592 Client ID to associate clients. See the format of
2597 Channel ID to associate channels. See the format of
2601 When encoding different IDs into the ID Payload, all fields are always
2602 in MSB first order. The IP address, port, and/or the random number
2603 are encoded in the MSB first order.
2607 2.5 Packet Encryption And Decryption
2609 SILC packets are encrypted almost entirely. Only small part of SILC
2610 header is not encrypted as described in section 5.2 SILC Packet Header.
2611 The SILC Packet header is the first part of a packet to be encrypted
2612 and it is always encrypted with the key of the next receiver of the
2613 packet. The data payload area of the packet is always entirely
2614 encrypted and it is usually encrypted with the next receiver's key.
2615 However, there are some special packet types and packet payloads
2616 that require special encryption process. These special cases are
2617 described in the next sections. First is described the normal packet
2622 2.5.1 Normal Packet Encryption And Decryption
2624 Normal SILC packets are encrypted with the session key of the next
2625 receiver of the packet. The entire SILC Packet header and the packet
2626 data payload is is also encrypted with the same key. Padding of the
2627 packet is also encrypted always with the session key, also in special
2628 cases. Computed MAC of the packet must not be encrypted.
2630 Decryption process in these cases are straightforward. The receiver
2631 of the packet MUST first decrypt the SILC Packet header, or some parts
2632 of it, usually first 16 bytes of it. Then the receiver checks the
2633 packet type from the decrypted part of the header and can determine
2634 how the rest of the packet must be decrypted. If the packet type is
2635 any of the special cases described in the following sections the packet
2636 decryption is special. If the packet type is not among those special
2637 packet types rest of the packet can be decrypted with the same key.
2639 With out a doubt, this sort of decryption processing causes some
2640 overhead to packet decryption, but never the less, is required.
2644 2.5.2 Channel Message Encryption And Decryption
2646 Channel Messages (Channel Message Payload) are always encrypted with
2647 the channel specific key. However, the SILC Packet header is not
2648 encrypted with that key. As in normal case, the header is encrypted
2649 with the key of the next receiver of the packet, who ever that might
2650 be. Note that in this case the encrypted data area is not touched
2651 at all; it MUST NOT be re-encrypted with the session key.
2653 Receiver of a channel message, who ever that is, is REQUIRED to decrypt
2654 the SILC Packet header to be able to even recognize the packet to be as
2655 channel message. This is same procedure as for normal SILC packets.
2656 As the receiver founds the packet to be channel message, rest of the
2657 packet processing is special. Rest of the SILC Packet header is
2658 decrypted with the same session key along with the padding of the
2659 packet. After that the packet is protected with the channel specific
2660 key and thus can be decrypted only if the receiver is the client on
2661 the channel. See section 2.7 Packet Padding Generation for more
2662 information about padding on special packets.
2664 If the receiver of the channel message is router which is routing the
2665 message to another router then it MUST decrypt the Channel Message
2666 payload. Between routers (that is, between cells) channel messages
2667 are protected with session keys shared between the routers. This
2668 causes another special packet processing for channel messages. If
2669 the channel message is received from another router then the entire
2670 packet, including Channel Message payload, MUST be encrypted with the
2671 session key shared between the routers. In this case the packet
2672 decryption process is as with normal SILC packets. Hence, if the
2673 router is sending channel message to another router the Channel
2674 Message payload MUST have been decrypted and MUST be re-encrypted
2675 with the session key shared between the another router. In this
2676 case the packet encryption is as with any normal SILC packet.
2678 It must be noted that this is only when the channel messages are sent
2679 from router to another router. In all other cases the channel
2680 message encryption and decryption is as described above. This
2681 different processing of channel messages with router to router
2682 connection is because channel keys are cell specific. All cells have
2683 their own channel keys thus the channel message traveling from one
2684 cell to another MUST be protected as it would be any normal SILC
2687 If the SILC_CMODE_PRIVKEY channel mode has been set for the channel
2688 then the router cannot decrypt the packet as it does not know the
2689 private key. In this case the entire packet MUST be encrypted with
2690 the session key and sent to the router. The router receiving the
2691 packet MUST check the channel mode and decrypt the packet accordingly.
2695 2.5.3 Private Message Encryption And Decryption
2697 By default, private message in SILC are protected by session keys.
2698 In this case the private message encryption and decryption process is
2699 equivalent to normal packet encryption and decryption.
2701 However, private messages MAY be protected with private message key
2702 which causes the packet to be special packet. The procedure in this
2703 case is very much alike to channel packets. The actual private message
2704 is encrypted with the private message key and other parts of the
2705 packet is encrypted with the session key. See 2.7 Packet Padding
2706 Generation for more information about padding on special packets.
2708 The difference from channel message processing is that server or router
2709 en route never decrypts the actual private message, as it does not
2710 have the key to do that. Thus, when sending packets between router
2711 the processing is same as in any other case as well; the packet's header
2712 and padding is protected by the session key and the data area is not
2715 The true receiver of the private message, client, that is, is able
2716 to decrypt the private message as it shares the key with the sender
2721 2.6 Packet MAC Generation
2723 Data integrity of a packet is protected by including a message
2724 authentication code (MAC) at the end of the packet. The MAC is computed
2725 from shared secret MAC key, that is established by the SILC Key Exchange
2726 protocol, from packet sequence number, and from the encrypted packet
2727 data. The MAC is always computed after packet is encrypted. This is
2728 so called Encrypt-Then-MAC order; packet is first encrypted, then MAC
2729 is computed from the encrypted data.
2731 The MAC is computed from entire packet. Every bit of data in the packet,
2732 including SILC Packet Header is used in the MAC computing. This way
2733 the entire packet becomes authenticated.
2735 Hence, packet's MAC generation is as follows:
2737 mac = MAC(key, sequence number | Encrypted SILC packet)
2739 The MAC key is negotiated during the SKE protocol. The sequence number
2740 is a 32 bit MSB first value starting from zero for first packet and
2741 increasing for subsequent packets, finally wrapping after 2^32 packets.
2742 The value is never reset, not even after rekey has been performed.
2743 However, rekey MUST be performed before the sequence number wraps
2744 and repeats from zero. Note that the sequence number is incremented only
2745 when MAC is computed for a packet. If packet is not encrypted and MAC is
2746 not computed then the sequence number is not incremented. Hence, the
2747 sequence number is zero for the very first encrypted packet.
2749 See [SILC1] for defined and allowed MAC algorithms.
2753 2.7 Packet Padding Generation
2755 Padding is needed in the packet because the packet is encrypted. It
2756 MUST always be multiple by eight (8) or multiple by the block size
2757 of the cipher, which ever is larger. The padding is always encrypted.
2759 For normal packets the padding is added after the SILC Packet Header
2760 and between the Data Payload area. The padding for normal packets
2761 may be calculated as follows:
2764 padding_length = 16 - (packet_length mod block_size)
2765 if (padding_length < 8)
2766 padding_length += block_size
2769 The `block_size' is the block size of the cipher. The maximum padding
2770 length is 128 bytes, and minimum is 8 bytes. For example, packets that
2771 include a passphrase or a password for authentication purposes SHOULD
2772 pad the packet up to the maximum padding length. The maximum padding
2773 is calculated as follows:
2776 padding_length = 128 - (packet_length mod block_size)
2779 For special packets the padding calculation is different as special
2780 packets may be encrypted differently. In these cases the encrypted
2781 data area MUST already be multiple by the block size thus in this case
2782 the padding is calculated only for SILC Packet Header, not for any
2783 other area of the packet. The same algorithm works in this case as
2784 well, except that the `packet length' is now the SILC Packet Header
2787 The padding MUST be random data, preferably, generated by
2788 cryptographically strong random number generator for each packet
2793 2.8 Packet Compression
2795 SILC Packets MAY be compressed. In this case the data payload area
2796 is compressed and all other areas of the packet MUST remain as they
2797 are. After compression is performed for the data area, the length
2798 field of Packet Header MUST be set to the compressed length of the
2801 The compression MUST always be applied before encryption. When
2802 the packet is received and decrypted the data area MUST be decompressed.
2803 Note that the true sender of the packet MUST apply the compression and
2804 the true receiver of the packet MUST apply the decompression. Any
2805 server or router en route SHOULD NOT decompress the packet.
2811 The sender of the packet MUST assemble the SILC Packet Header with
2812 correct values. It MUST set the Source ID of the header as its own
2813 ID, unless it is forwarding the packet. It MUST also set the Destination
2814 ID of the header to the true destination. If the destination is client
2815 it will be Client ID, if it is server it will be Server ID and if it is
2816 channel it will be Channel ID.
2818 If the sender wants to compress the packet it MUST apply the
2819 compression now. Sender MUST also compute the padding as described
2820 in above sections. Then sender MUST encrypt the packet as has been
2821 described in above sections according whether the packet is normal
2822 packet or special packet. Then sender MUST compute the MAC of the
2823 packet. The computed MAC MUST NOT be encrypted.
2827 2.10 Packet Reception
2829 On packet reception the receiver MUST check that all fields in the
2830 SILC Packet Header are valid. It MUST check the flags of the
2831 header and act accordingly. It MUST also check the MAC of the packet
2832 and if it is to be failed the packet MUST be discarded. Also if the
2833 header of the packet includes any bad fields the packet MUST be
2836 See above sections on the decryption process of the received packet.
2838 The receiver MUST also check that the ID's in the header are valid
2839 ID's. Unsupported ID types or malformed ID's MUST cause packet
2840 rejection. The padding on the reception is always ignored.
2842 The receiver MUST also check the packet type and start parsing the
2843 packet according to the type. However, note the above sections on
2844 special packet types and their parsing.
2850 Routers are the primary entities in the SILC network that takes care
2851 of packet routing. However, normal servers routes packets as well, for
2852 example, when they are routing channel message to the local clients.
2853 Routing is quite simple as every packet tells the true origin and the
2854 true destination of the packet.
2856 It is still RECOMMENDED for routers that has several routing connections
2857 to create route cache for those destinations that has faster route than
2858 the router's primary route. This information is available for the router
2859 when other router connects to the router. The connecting party then
2860 sends all of its locally connected clients, servers and channels. These
2861 informations helps to create the route cache. Also, when new channels
2862 are created to a cell its information is broadcasted to all routers
2863 in the network. Channel ID's are based on router's ID thus it is easy
2864 to create route cache based on these informations. If faster route for
2865 destination does not exist in router's route cache the packet MUST be
2866 routed to the primary route (default route).
2868 However, there are some issues when routing channel messages to group
2869 of users. Routers are responsible of routing the channel message to
2870 other routers, local servers and local clients as well. Routers MUST
2871 send the channel message to only one router in the network, preferably
2872 to the shortest route to reach the channel users. The message can be
2873 routed into either upstream or downstream. After the message is sent
2874 to a router in the network it MUST NOT be sent to any other router in
2875 either same route or other route. The message MUST NOT be routed to
2876 the router it came from.
2878 When routing for example private messages they should be routed to the
2879 shortest route always to reach the destination client as fast as possible.
2881 For server which receives a packet to be routed to its locally connected
2882 client the server MUST check whether the particular packet type is
2883 allowed to be routed to the client. Not all packets may be sent by
2884 some odd entity to client that is indirectly connected to the sender.
2885 See section 2.3 SILC Packet Types and paragraph about indirectly connected
2886 entities and sending packets to them. The section mentions the packets
2887 that may be sent to indirectly connected entities. It is clear that
2888 server cannot send, for example, disconnect packet to client that is not
2889 directly connected to the server.
2891 Routers form a ring in the SILC network. However, routers may have other
2892 direct connections to other routers in the network too. This can cause
2893 interesting routing problems in the network. Since the network is a ring,
2894 the packets usually should be routed into clock-wise direction, or if it
2895 cannot be used then always counter clock-wise (primary route) direction.
2896 Problems may arise when a faster direct route exists and router is routing
2897 a channel message. Currently channel messages must be routed either
2898 in upstream or downstream, they cannot be routed to other direct routes.
2899 The SILC protocol should have a shortest path discovery protocol, and some
2900 existing routing protocol, that can handle a ring network with other
2901 direct routes inside the ring (so called hybrid ring-mesh topology),
2902 MAY be defined to be used with the SILC protocol. Additional
2903 specifications MAY be written on the subject to permeate this
2908 2.12 Packet Broadcasting
2910 SILC packets MAY be broadcasted in SILC network. However, only router
2911 server may send or receive broadcast packets. Client and normal server
2912 MUST NOT send broadcast packets and they MUST ignore broadcast packets
2913 if they receive them. Broadcast packets are sent by setting Broadcast
2914 flag to the SILC packet header.
2916 Broadcasting packets means that the packet is sent to all routers in
2917 the SILC network, except to the router that sent the packet. The router
2918 receiving broadcast packet MUST send the packet to its primary route.
2919 The fact that SILC routers may have several router connections can
2920 cause problems, such as race conditions inside the SILC network, if
2921 care is not taken when broadcasting packets. Router MUST NOT send
2922 the broadcast packet to any other route except to its primary route.
2924 If the primary route of the router is the original sender of the packet
2925 the packet MUST NOT be sent to the primary route. This may happen
2926 if router has several router connections and some other router uses
2927 the router as its primary route.
2929 Routers use broadcast packets to broadcast for example information
2930 about newly registered clients, servers, channels etc. so that all the
2931 routers may keep these informations up to date.
2935 3 Security Considerations
2937 Security is central to the design of this protocol, and these security
2938 considerations permeate the specification. Common security considerations
2939 such as keeping private keys truly private and using adequate lengths for
2940 symmetric and asymmetric keys must be followed in order to maintain the
2941 security of this protocol.
2947 [SILC1] Riikonen, P., "Secure Internet Live Conferencing (SILC),
2948 Protocol Specification", Internet Draft, May 2002.
2950 [SILC3] Riikonen, P., "SILC Key Exchange and Authentication
2951 Protocols", Internet Draft, May 2002.
2953 [SILC4] Riikonen, P., "SILC Commands", Internet Draft, May 2002.
2955 [IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
2958 [IRC-ARCH] Kalt, C., "Internet Relay Chat: Architecture", RFC 2810,
2961 [IRC-CHAN] Kalt, C., "Internet Relay Chat: Channel Management", RFC
2964 [IRC-CLIENT] Kalt, C., "Internet Relay Chat: Client Protocol", RFC
2967 [IRC-SERVER] Kalt, C., "Internet Relay Chat: Server Protocol", RFC
2970 [SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
2973 [PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
2976 [SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
2979 [PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
2980 Infrastructure, Certificate and CRL Profile", RFC 2459,
2983 [Schneier] Schneier, B., "Applied Cryptography Second Edition",
2984 John Wiley & Sons, New York, NY, 1996.
2986 [Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
2989 [OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
2990 RFC 2412, November 1998.
2992 [ISAKMP] Maughan D., et al, "Internet Security Association and
2993 Key Management Protocol (ISAKMP)", RFC 2408, November
2996 [IKE] Harkins D., and Carrel D., "The Internet Key Exchange
2997 (IKE)", RFC 2409, November 1998.
2999 [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
3000 Authentication", RFC 2104, February 1997.
3002 [PKCS1] Kalinski, B., and Staddon, J., "PKCS #1 RSA Cryptography
3003 Specifications, Version 2.0", RFC 2437, October 1998.
3005 [RFC2119] Bradner, S., "Key Words for use in RFCs to Indicate
3006 Requirement Levels", BCP 14, RFC 2119, March 1997.
3008 [SFTP] Ylonen T., and Lehtinen S., "Secure Shell File Transfer
3009 Protocol", Internet Draft, March 2001.
3011 [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO
3012 10646", RFC 2279, January 1998.
3019 Snellmaninkatu 34 A 15
3023 EMail: priikone@iki.fi
3025 This Internet-Draft expires 15 November 2002