7 Network Working Group P. Riikonen
9 draft-riikonen-silc-pp-00.txt 28 June 2000
17 This document is an Internet-Draft. Internet-Drafts are working
18 documents of the Internet Engineering Task Force (IETF), its areas,
19 and its working groups. Note that other groups may also distribute
20 working documents as Internet-Drafts.
22 Internet-Drafts are draft documents valid for a maximum of six
23 months and may be updated, replaced, or obsoleted by other
24 documents at any time. It is inappropriate to use Internet-Drafts
25 as reference material or to cite them other than as
28 To learn the current status of any Internet-Draft, please check the
29 ``1id-abstracts.txt'' listing contained in the Internet-Drafts
30 Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),
31 munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or
32 ftp.isi.edu (US West Coast).
34 The distribution of this memo is unlimited.
39 This memo describes a Packet Protocol used in the Secure Internet Live
40 Conferencing (SILC) protocol specified in the Secure Internet Live
41 Conferencing, Protocol Specification Internet Draft [SILC1]. This
42 protocol describes the packet types and packet payloads which defines
43 the contents of the packets. The protocol provides secure binary packet
44 protocol that assures that the contents of the packets are secured and
60 Internet Draft SILC Packet Protocol 28 June 2000
65 1 Introduction .................................................. 3
66 2 SILC Packet Protocol .......................................... 4
67 2.1 SILC Packet ............................................... 4
68 2.2 SILC Packet Header ........................................ 5
69 2.3 SILC Packet Types ......................................... 7
70 2.3.1 SILC Packet Payloads ................................ 15
71 2.3.2 Disconnect Payload .................................. 15
72 2.3.3 Success Payload ..................................... 16
73 2.3.4 Failure Payload ..................................... 16
74 2.3.5 Reject Payload ...................................... 17
75 2.3.6 Notify Payload ...................................... 17
76 2.3.7 Error Payload ....................................... 18
77 2.3.8 Channel Message Payload ............................. 19
78 2.3.9 Channel Key Payload ................................. 20
79 2.3.10 Private Message Payload ............................ 23
80 2.3.11 Private Message Key Payload ........................ 24
81 2.3.12 Command Payload .................................... 25
82 2.3.12.1 Command Argument Payload .................. 25
83 2.3.13 Command Reply Payload .............................. 26
84 2.3.14 Connection Auth Request Payload .................... 27
85 2.3.15 New ID Payload ..................................... 28
86 2.3.16 New ID List Payload ................................ 29
87 2.3.17 New Client Payload ................................. 29
88 2.3.18 New Server Payload ................................. 31
89 2.3.19 New Channel Payload ................................ 31
90 2.3.20 New Channel User Payload ........................... 32
91 2.3.21 New Channel List Payload ........................... 33
92 2.3.22 New Channel User List Payload ...................... 34
93 2.3.23 Replace ID Payload ................................. 34
94 2.3.24 Remove ID Payload .................................. 35
95 2.4 SILC ID Types ............................................. 36
96 2.5 Packet Encryption And Decryption .......................... 37
97 2.5.1 Normal Packet Encryption And Decryption ............. 37
98 2.5.2 Channel Message Encryption And Decryption ........... 37
99 2.5.3 Private Message Encryption And Decryption ........... 38
100 2.6 Packet MAC Generation ..................................... 39
101 2.7 Packet Padding Generation ................................. 39
102 2.8 Packet Compression ........................................ 40
103 2.9 Packet Sending ............................................ 40
104 2.10 Packet Reception ......................................... 41
105 2.11 Packet Broadcasting ...................................... 41
106 2.12 Packet Routing ........................................... 42
107 2.13 Packet Tunneling ......................................... 42
108 3 Security Considerations ....................................... 43
109 4 References .................................................... 43
110 5 Author's Address .............................................. 44
116 Internet Draft SILC Packet Protocol 28 June 2000
121 Figure 1: Typical SILC Packet
122 Figure 2: SILC Packet Header
123 Figure 3: Disconnect Payload
124 Figure 4: Success Payload
125 Figure 5: Failure Payload
126 Figure 6: Reject Payload
127 Figure 7: Notify Payload
128 Figure 8: Error Payload
129 Figure 9: Channel Message Payload
130 Figure 10: Channel Key Payload
131 Figure 11: Private Message Payload
132 Figure 12: Private Message Key Payload
133 Figure 13: Command Payload
134 Figure 14: Command Argument Payload
135 Figure 15: Connection Auth Request Payload
136 Figure 16: New ID Payload
137 Figure 17: New Client Payload
138 Figure 18: New Server Payload
139 Figure 19: New Channel Payload
140 Figure 20: New Channel User Payload
141 Figure 21: Replace ID Payload
142 Figure 22: Remove ID Payload
147 This document describes a Packet Protocol used in the Secure Internet
148 Live Conferencing (SILC) protocol specified in the Secure Internet Live
149 Conferencing, Protocol Specification Internet Draft [SILC1]. This
150 protocol describes the packet types and packet payloads which defines
151 the contents of the packets. The protocol provides secure binary packet
152 protocol that assures that the contents of the packets are secured and
155 The basis of SILC protocol relies in the SILC packets and it is with
156 out a doubt the most important part of the protocol. It is also probably
157 the most complicated part of the protocol. Packets are used all the
158 time in the SILC network to send messages, commands and other information.
159 All packets in SILC network are always encrypted and their integrity
160 is assured by computed MACs. The protocol defines several packet types
161 and packet payloads. Each packet type usually has a specific packet
162 payload that actually defines the contents of the packet. Each packet
163 also includes a default SILC Packet Header that provides sufficient
164 information about the origin of the packet and destination of the
172 Internet Draft SILC Packet Protocol 28 June 2000
175 2 SILC Packet Protocol
179 SILC packets deliver messages from sender to receiver securely by
180 encrypting important fields of the packet. The packet consists of
181 default SILC Packet Header, Padding, Packet Payload data, and, packet
184 The following diagram illustrates typical SILC packet.
187 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
188 | n bytes | 1 - n bytes | n bytes | n bytes
189 | SILC Header | Padding | Data Payload | MAC
190 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
192 Figure 1: Typical SILC Packet
195 SILC Header is always the first part of the packet and its purpose
196 is to provide information about the packet. It provides for example
197 the packet type, origin of the packet and the destination of the packet.
198 The header is variable in length and first two (2) bytes of the
199 header (thus first two bytes of the packet) are not encrypted. The
200 first two (2) bytes are the length of the packet which is not encrypted.
201 See following section for description of SILC Packet header. Packets
202 without SILC header or with malformed SILC header must be dropped.
204 Padding follows the packet header. The purpose of the padding is to
205 make the packet multiple by eight (8) or by the block size of the
206 cipher used in the encryption, which ever is larger. The maximum
207 length of padding is currently 16 bytes. The padding is always
210 Data payload area follows padding and it is the actual data of the
211 packet. The packet data is the packet payloads defined in this
212 protocol. The data payload area is always encrypted.
214 The last part of SILC packet is the packet MAC that assures the
215 integrity of the packet. The MAC is always computed from the packet
216 before the encryption is applied to the packet. If compression is used
217 in the packet the MAC is computed after the compression has been
218 applied. The compression, on the other hand, is always applied before
221 All fields in all packet payloads are always in MSB (most significant
228 Internet Draft SILC Packet Protocol 28 June 2000
231 2.2 SILC Packet Header
233 The default SILC packet header is applied to all SILC packets and it is
234 variable in length. The purpose of SILC Packet header is to provide
235 detailed information about the packet. The receiver of the packet uses
236 the packet header to parse the packet and gain other relevant parameters
239 Following diagram represents the default SILC header format.
240 (*) indicates that this field is never encrypted. Other fields are
245 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
246 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
247 | Payload Length * | Flags | Packet Type |
248 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
249 | Source ID Length | Destination ID Length |
250 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
256 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
262 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
264 Figure 2: SILC Packet Header
267 o Payload Length (2 bytes) - Is the length of the packet
268 not including the padding of the packet. This field must
269 not be encrypted but must always be authenticated.
271 o Flags (1 byte) - Indicates flags to be used in packet
272 processing. Several flags may be set by ORing the flags
275 Following flags are reserved for this field:
284 Internet Draft SILC Packet Protocol 28 June 2000
289 In this case the field is ignored.
292 Private Message Key 0x01
294 Indicates that the packet must include private
295 message that is encrypted using private key set by
296 client. Servers does not know anything about this
297 key and this causes that the private message is
298 not handled by the server at all, it is just
299 passed along. See section 2.5.3 Private Message
300 Encryption And Decryption for more information.
305 Marks the packet to be broadcasted. Client cannot
306 send broadcast packet and normal server cannot send
307 broadcast packet. Only router server may send broadcast
308 packet. The router receiving of packet with this flag
309 set must send (broadcast) the packet to its primary
310 route. If router has several router connections the
311 packet may be sent only to the primary route. See
312 section 2.11 Packet Broadcasting for description of
318 Marks that the packet is tunneled. Tunneling means
319 that extra SILC Packet Header has been applied to the
320 original packet. The outer header has this flag
321 set. See section 2.13 Packet Tunneling for more
326 o Packet Type (1 byte) - Is the type of the packet. Receiver
327 uses this field to parse the packet. See section 2.3
328 SILC Packets for list of defined packet types.
330 o Source ID Length (2 bytes) - Indicates the length of the
331 Source ID field in the header, not including this or any
340 Internet Draft SILC Packet Protocol 28 June 2000
343 o Destination ID Length (2 bytes) - Indicates the length of the
344 Destination ID field in the header, not including this or
347 o Src ID Type (1 byte) - Indicates the type of ID in the
348 Source ID field. See section 2.4 SILC ID Types for
351 o Source ID (variable length) - The actual source ID that
352 indicates who is the original sender of the packet.
354 o Dst ID Type (1 byte) - Indicates the type of ID in the
355 Destination ID field. See section 2.4 SILC ID Types for
358 o Destination ID (variable length) - The actual source ID that
359 indicates who is the end receiver of the packet.
362 2.3 SILC Packet Types
364 SILC packet types defines the contents of the packet and it is used by
365 the receiver to parse the packet. The packet type is 8 bits, as a one
366 byte, in length. The range for the packet types are from 0 - 255,
367 where 0 is never sent and 255 is currently reserved for future
368 extensions and must not be defined to any other purpose. Every SILC
369 specification compliant implementation should support all of these packet
372 The below list of the SILC Packet types includes reference to the packet
373 payload as well. Packet payloads are the actual packet, that is, the data
374 that the packet consists of. Each packet type defines packet payload
375 which usually may only be sent with the specific packet type.
377 Most of the packets are packets that must be destined directly to entity
378 that is connected to the sender. It is not allowed, for example, for
379 router to send disconnect packet to client that is not directly connected
380 to the router. However, there are some special packet types that may
381 be destined to some entity that the sender has not direct connection
382 with. These packets are for example private message packets, channel
383 message packets, command packets and some other packets that may be
384 broadcasted in the SILC network. If the packet is allowed to be sent to
385 indirectly connected entity it is mentioned separately in the packet
386 description (unless it is obvious as in private and channel message
387 packets). Other packets must not be sent or accepted, if sent, to
388 indirectly connected entities.
390 List of SILC Packet types are defined as follows.
396 Internet Draft SILC Packet Protocol 28 June 2000
401 This type is reserved and it is never sent.
404 1 SILC_PACKET_DISCONNECT
406 This packet is sent to disconnect the remote end. Reason of
407 the disconnection is sent inside the packet payload. Client
408 usually does not send this packet.
410 Payload of the packet: See section 2.3.2 Disconnect Payload
413 2 SILC_PACKET_SUCCESS
415 This packet is sent upon successful execution of some protocol.
416 The status of the success is sent in the packet.
418 Payload of the packet: See section 2.3.3 Success Payload
421 3 SILC_PACKET_FAILURE
423 This packet is sent upon failure of some protocol. The status
424 of the failure is sent in the packet.
426 Payload of the packet: See section 2.3.4 Failure Payload
431 This packet may be sent upon rejection of some protocol.
432 The status of the rejection is sent in the packet.
434 Payload of the packet: See section 2.3.5 Reject Payload
439 This packet is used to send notify message, usually from
440 server to client, although it may be sent from server to another
441 server as well. Client never sends this packet. Server may
442 send this packet to channel as well when the packet is
443 distributed to all clients on the channel. Receiver of this
444 packet may ignore the packet if it chooses so. However, it
445 should not be ignored.
452 Internet Draft SILC Packet Protocol 28 June 2000
455 Payload of the packet: See section 2.3.6 Notify Payload.
460 This packet is sent when an error occurs. Server may
461 send this packet. Client never sends this packet. The
462 client may entirely ignore the packet, however, server is
463 most likely to take action anyway.
465 Payload of the packet: See section 2.3.7 Error Payload.
468 7 SILC_PACKET_CHANNEL_MESSAGE
470 This packet is used to send messages to channels. The packet
471 includes Channel ID of the channel and the actual message to
472 the channel. Messages sent to the channel are always protected
473 by channel specific keys. Channel Keys are distributed by
474 SILC_PACKET_CHANNEL_KEY packet.
476 When client sends this packet the destination ID in the SILC
477 header must be the Channel ID of the channel the message is
478 destined to. If server sends this packet to a client the
479 destination ID in the SILC header must be the Client ID of
480 the client receiving the packet.
482 If server sends this packet to router or if router sends this
483 packet to server or another router the destination ID in the
484 SILC header must be the Channel ID of the channel. Server
485 (including router) distributes this packet only to its local
486 clients who are joined to the channel. Servers and routers
487 also determines who are on the channel and when this packet
488 needs to be sent, as described in section Client To Client
491 Payload of the packet: See section 2.3.8 Channel Message
495 8 SILC_PACKET_CHANNEL_KEY
497 This packet is used to distribute new key for particular
498 channel. Each channel has their own independent keys that
499 is used to protect the traffic on the channel. Only server
500 may send this packet. This packet may be sent to entity
501 that is indirectly connected to the sender.
508 Internet Draft SILC Packet Protocol 28 June 2000
511 Payload of the packet: See section 2.3.9 Channel Key Payload
514 9 SILC_PACKET_PRIVATE_MESSAGE
516 This packet is used to send private messages from client
517 to another client. By default, private messages are protected
518 by session keys established by normal key exchange protocol.
519 However, it is possible to use specific key to protect private
520 messages. SILC_PACKET_PRIVATE_MESSAGE_KEY packet is used to
521 agree the key with the remote client. Pre-shared key may be
522 used as well if both of the client knows it, however, it needs
523 to be agreed outside SILC. See more of this in [SILC1].
525 Payload of the packet: See section 2.3.10 Private Message
529 10 SILC_PACKET_PRIVATE_MESSAGE_KEY
531 This packet is used to agree about a key to be used to protect
532 the private messages between two clients. If this is not sent
533 the normal session key is used to protect the private messages
534 inside SILC network. Agreeing to use specific key to protect
535 private messages adds security, as no server between the two
536 clients will be able to decrypt the private message. However,
537 servers inside SILC network are considered to be trusted, thus
538 using normal session key to protect private messages does not
539 degree security. Whether to agree to use specific keys by
540 default or to use normal session keys by default, is
541 implementation specific issue. See more of this in [SILC1].
543 Payload of the packet: See section 2.3.11 Private Message
547 11 SILC_PACKET_COMMAND
549 This packet is used to send commands from client to server.
550 Server may send this packet to other servers as well. All
551 commands are listed in their own section SILC Command Types
552 in [SILC1]. The contents of this packet is command specific.
553 This packet may be sent to entity that is indirectly connected
556 Payload of the packet: See section 2.3.12 Command Payload
564 Internet Draft SILC Packet Protocol 28 June 2000
567 12 SILC_PACKET_COMMAND_REPLY
569 This packet is send as reply to the SILC_PACKET_COMMAND packet.
570 The contents of this packet is command specific. This packet
571 maybe sent to entity that is indirectly connected to the sender.
573 Payload of the packet: See section 2.3.13 Command Reply
574 Payload and section 2.3.12 Command
578 13 SILC_PACKET_KEY_EXCHANGE
580 This packet is used to start SILC Key Exchange Protocol,
581 described in detail in [SILC3].
583 Payload of the packet: Payload of this packet is described
584 in the section SILC Key Exchange
585 Protocol and its sub sections in
589 14 SILC_PACKET_KEY_EXCHANGE_1
591 This packet is used as part of the SILC Key Exchange Protocol.
593 Payload of the packet: Payload of this packet is described
594 in the section SILC Key Exchange
595 Protocol and its sub sections in
599 15 SILC_PACKET_KEY_EXCHANGE_2
601 This packet is used as part of the SILC Key Exchange Protocol.
603 Payload of the packet: Payload of this packet is described
604 in the section SILC Key Exchange
605 Protocol and its sub sections in
609 16 SILC_PACKET_CONNECTION_AUTH_REQUEST
611 This packet is used to request the authentication method to
612 be used in the SILC Connection Authentication Protocol. If
613 initiator of the protocol does not know the mandatory
614 authentication method this packet is used to determine it.
620 Internet Draft SILC Packet Protocol 28 June 2000
623 The party receiving this payload must respond with the same
624 packet including the mandatory authentication method.
626 Payload of the packet: See section 2.3.14 Connection Auth
630 17 SILC_PACKET_CONNECTION_AUTH
632 This packet is used to start and perform the SILC Connection
633 Authentication Protocol. This protocol is used to authenticate
634 the connecting party. The protocol is described in detail in
637 Payload of the packet: Payload of this packet is described
638 in the section SILC Authentication
639 Protocol and it sub sections in [SILC].
642 18 SILC_PACKET_NEW_ID
644 This packet is used to distribute new ID's from server to
645 router and from router to all routers in the SILC network.
646 This is used when for example new client is registered to
647 SILC network. The newly created ID's of these operations are
648 distributed by this packet. Only server may send this packet,
649 however, client must be able to receive this packet.
651 Payload of the packet: See section 2.3.15 New ID Payload
654 19 SILC_PACKET_NEW_ID_LIST
656 This packet is used to distribute list of new ID's from
657 server to routers. This is equivalent to previous packet
658 type except that it may include several ID's. Client must
659 not send this packet.
661 Payload of the packet: See section 2.3.16 New ID List
665 20 SILC_PACKET_NEW_CLIENT
667 This packet is used by client to register itself to the
668 SILC network. This is sent after key exchange and
669 authentication protocols has been completed. Client sends
670 various information about itself in this packet.
676 Internet Draft SILC Packet Protocol 28 June 2000
679 Payload of the packet: See section 2.3.17 New Client Payload
682 21 SILC_PACKET_NEW_SERVER
684 This packet is used by server to register itself to the
685 SILC network. This is sent after key exchange and
686 authentication protocols has been completed. Server sends
687 this to the router it connected to, or, if router was
688 connecting, to the connected router. Server sends
689 its Server ID and other information in this packet.
690 Client must not send or receive this packet.
692 Payload of the packet: See section 2.3.18 New Server Payload
695 22 SILC_PACKET_NEW_CHANNEL
697 This packet is used to notify routers about newly created
698 channel. Channels are always created by the router and it must
699 notify other routers about the created channel. Router sends
700 this packet to its primary route. Client must not send this
701 packet. This packet maybe sent to entity that is indirectly
702 connected to the sender.
704 Payload of the packet: See section 2.3.19 New Channel Payload
707 23 SILC_PACKET_NEW_CHANNEL_USER
709 This packet is used to notify routers about new user on channel.
710 The packet is sent after user has joined to the channel. Server
711 may send this packet to its router and router may send this to
712 its primary router. Client must not send this packet. This
713 packet maybe sent to entity that is indirectly connected to the
716 Payload of the packet: See section 2.3.20 New Channel User
720 24 SILC_PACKET_NEW_CHANNEL_LIST
722 This packet is used to distribute list of created channels
723 from server to routers. This is equivalent to the packet
724 SILC_PACKET_NEW_CHANNEL except that it may include several
725 payloads. Client must not send this packet.
732 Internet Draft SILC Packet Protocol 28 June 2000
735 Payload of the packet: See section 2.3.21 New Channel List
739 25 SILC_PACKET_NEW_CHANNEL_USER_LIST
741 This packet is used to distribute list of users on specific
742 channel from server to routers. This is equivalent to the
743 packet SILC_PACKET_NEW_CHANNEL_USER except that it may
744 include several payloads. Client must not send this packet.
746 Payload of the packet: See section 2.3.22 New Channel User
750 26 SILC_PACKET_REPLACE_ID
752 This packet is used to replace old ID with new ID sent in
753 the packet payload. For example, when client changes its
754 nickname new ID is created and this packet can be used to
755 distribute the new ID and the old ID is removed when it is
756 send in the packet. Client cannot send or receive this
757 packet. This packet maybe sent to entity that is indirectly
758 connected to the sender.
760 Payload of the packet: See section 2.3.23 Replace ID Payload
763 27 SILC_PACKET_REMOVE_ID
765 This packet is used to removed ID. For example, when client
766 exits SILC network its ID is removed. Client must not send
767 this packet. This packet maybe sent to entity that is
768 indirectly connected to the sender.
770 Payload of the packet: See section 2.3.24 Remove ID Payload
775 This packet is used to indicate that re-key must be performed
776 for session keys. See section Session Key Regeneration in
777 [SILC1] for more information. This packet does not have
788 Internet Draft SILC Packet Protocol 28 June 2000
791 29 SILC_PACKET_REKEY_DONE
793 This packet is used to indicate that re-key is performed and
794 new keys must be used hereafter. This is sent only if re-key
795 was done without PFS option. If PFS is set, this is not sent
796 as SILC Key Exchange protocol is executed. This packet does
802 Currently undefined commands.
807 This type is reserved for future extensions and currently it
811 2.3.1 SILC Packet Payloads
813 All payloads resides in the main data area of the SILC packet. However
814 all payloads must be at the start of the data area after the default
815 SILC packet header and padding. All fields in the packet payload are
816 always encrypted, as, they reside in the data area of the packet which
819 Payloads described in this section are common payloads that must be
820 accepted anytime during SILC session. Most of the payloads may only
821 be sent with specific packet type which is defined in the description
824 There are a lot of other payloads in the SILC as well. However, they
825 are not common in the sense that they could be sent at any time.
826 These payloads are not described in this section. These are payloads
827 such as SILC Key Exchange payloads and so on. These are described
828 in [SILC1] and [SILC3].
831 2.3.2 Disconnect Payload
833 Disconnect payload is sent upon disconnection. The payload is simple;
834 reason of disconnection is sent to the disconnected party.
836 The payload may only be sent with SILC_PACKET_DISCONNECT packet. It
837 must not be sent in any other packet type. Following diagram represents
838 the Disconnect Payload.
844 Internet Draft SILC Packet Protocol 28 June 2000
848 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
849 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
851 ~ Disconnect Message ~
853 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
855 Figure 3: Disconnect Payload
860 o Disconnect Message (variable length) - Human readable
861 reason of the disconnection.
864 2.3.3 Success Payload
866 Success payload is sent when some protocol execution is successfully
867 completed. The payload is simple; indication of the success is sent.
868 This maybe any data, including binary or human readable data.
871 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
872 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
874 ~ Success Indication ~
876 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
878 Figure 4: Success Payload
881 o Success Indication (variable length) - Indication of
882 the success. This maybe for example some flag that
883 indicates the protocol and the success status or human
884 readable success message. The true length of this
885 payload is available by calculating it from the SILC
889 2.3.4 Failure Payload
891 This is opposite of Success Payload. Indication of failure of
892 some protocol is sent in the payload.
900 Internet Draft SILC Packet Protocol 28 June 2000
903 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
904 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
906 ~ Failure Indication ~
908 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
910 Figure 5: Failure Payload
913 o Failure Indication (variable length) - Indication of
914 the failure. This maybe for example some flag that
915 indicates the protocol and the failure status or human
916 readable failure message. The true length of this
917 payload is available by calculating it from the SILC
923 This payload is sent when some protocol is rejected to be executed.
924 Other operations may send this as well that was rejected. The
925 indication of the rejection is sent in the payload. The indication
926 may be binary or human readable data.
930 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
931 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
933 ~ Reject Indication ~
935 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
937 Figure 6: Reject Payload
940 o Reject Indication (variable length) - Indication of
941 the rejection. This maybe for example some flag that
942 indicates the protocol and the rejection status or human
943 readable rejection message. The true length of this
944 payload is available by calculating it from the SILC
950 Notify payload is used to send notify messages. The payload is usually
956 Internet Draft SILC Packet Protocol 28 June 2000
959 sent from server to client, however, server may send it to another
960 server as well. Client must not send this payload. The receiver of
961 this payload may totally ignore the contents of the payload, however,
962 notify message should be noted and possibly logged.
964 The payload may only be sent with SILC_PACKET_NOTIFY packet. It must
965 not be sent in any other packet type. Following diagram represents the
973 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
974 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
978 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
980 Figure 7: Notify Payload
983 o Notify Message (variable length) - Human readable notify
989 Error payload is sent upon error. Error may occur in various
990 conditions when server sends this packet. Client may not send this
991 payload but must be able to accept it. However, client may
992 totally ignore the contents of the packet as server is going to
993 take action on the error anyway. However, it is recommended
994 that the client takes error packet seriously.
998 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
999 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1003 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1005 Figure 8: Error Payload
1012 Internet Draft SILC Packet Protocol 28 June 2000
1015 o Error Message (variable length) - Human readable error
1019 2.3.8 Channel Message Payload
1021 Channel messages are the most common messages sent in the SILC.
1022 Channel Message Payload is used to send message to channels. These
1023 messages can only be sent if client has joined to some channel.
1024 Even though this packet is the most common in SILC it is still
1025 special packet. Some special handling on sending and reception
1026 of channel message is required.
1028 Padding must be applied into this payload since the payload is
1029 encrypted separately from other parts of the packet with the
1030 channel specific key. Hence the requirement of the padding.
1031 The padding should be random data. The packet must be made
1032 multiple by eight (8) or by the block size of the cipher, which
1035 The SILC header in this packet is encrypted with the session key
1036 of the next receiver of the packet. Nothing else is encrypted
1037 with that key. Thus, the actual packet and padding to be
1038 encrypted with the session key is SILC Header plus padding to it
1039 to make it multiple by eight (8) or multiple by the block size
1040 of the cipher, which ever is larger.
1042 Receiver of the the channel message packet is able to determine
1043 the channel the message is destined to by checking the destination
1044 ID from the SILC Packet header which tells the destination channel.
1045 The original sender of the packet is also determined by checking
1046 the source ID from the header which tells the who client sent
1049 The payload may only be sent with SILC_PACKET_CHANNEL_MESSAGE packet.
1050 It must not be sent in any other packet type. Following diagram
1051 represents the Channel Message Payload.
1053 (*) indicates that the field is not encrypted.
1068 Internet Draft SILC Packet Protocol 28 June 2000
1072 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
1073 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1074 | Nickname Length | |
1075 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1079 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1080 | Message Length | |
1081 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1085 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1086 | Padding Length | |
1087 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1091 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1093 ~ Initial Vector * ~
1095 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1097 Figure 9: Channel Message Payload
1100 o Nickname Length (2 bytes) - Indicates the length of the
1101 Nickname field, not including any other field.
1103 o Nickname (variable length) - Nickname of the sender of the
1104 channel message. This should not be trusted as a definite
1105 sender of the channel message. The SILC Packet Header in
1106 the packet indicates the true sender of the packet and
1107 client should verify that the nickname sent here belongs
1108 to the Client ID in the SILC Packet Header. This nickname
1109 is merely provided to be displayed by the client.
1111 If server is sending this packet this field is not included
1112 and zero (0) length must be set to the Nickname Length field.
1114 o Message Length (2 bytes) - Indicates the length of the
1115 the Message Data field in the payload, not including any
1124 Internet Draft SILC Packet Protocol 28 June 2000
1127 o Message Data (variable length) - The actual message to
1130 o Padding Length (2 bytes) - Indicates the length of the
1131 Padding field in the payload, not including any other
1134 o Padding (variable length) - The padding that must be
1135 applied because this payload is encrypted separately from
1136 other parts of the packet.
1138 o Initial Vector (variable length) - The initial vector
1139 that has been used in packet encryption. It needs to be
1140 used in the packet decryption as well. What this field
1141 includes is implementation issue. However, it is
1142 recommended that it would be random data or, perhaps,
1143 a timestamp. It is not recommended to use zero (0) as
1144 initial vector. This field is not encrypted. This field
1145 is not included into the padding calculation. Length
1146 of this field equals the cipher's block size. This field
1147 is, however, authenticated.
1150 2.3.9 Channel Key Payload
1152 All traffic in channels are protected by channel specific keys.
1153 Channel Key Payload is used to distribute channel keys to all
1154 clients on the particular channel. Channel keys are sent when
1155 the channel is created, when new user joins to the channel and
1156 whenever a user leaves a channel. Server creates the new
1157 channel key and distributes it to the clients by encrypting this
1158 payload with the session key shared between the server and
1159 the client. After that, client starts using the key received
1160 in this payload to protect the traffic on the channel.
1162 Channel keys are cell specific thus every router in cell have
1163 to create a channel key and distribute it if any client in the
1164 cell has joined to a channel. Channel traffic between cell's
1165 are not encrypted using channel keys, they are encrypted using
1166 normal session keys between two routers. Inside a cell, all
1167 channel traffic is encrypted with the specified channel key.
1168 Channel key should expire peridiocally, say, in one hour, in
1169 which case new channel key is created and distributed.
1171 The payload may only be sent with SILC_PACKET_CHANNEL_KEY packet.
1172 It must not be sent in any other packet type. Following diagram
1173 represents the Channel Key Payload.
1180 Internet Draft SILC Packet Protocol 28 June 2000
1184 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
1185 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1186 | Channel ID Length | |
1187 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1191 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1192 | Cipher Name Length | |
1193 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1198 | Channel Key Length | |
1199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1203 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1205 Figure 10: Channel Key Payload
1209 o Channel ID Length (2 bytes) - Indicates the length of the
1210 Channel ID field in the payload, not including any other
1213 o Channel ID (variable length) - The Channel ID of the
1214 channel this key is meant for.
1216 o Cipher Name Length (2 bytes) - Indicates the length of the
1217 Cipher name field in the payload, not including any other
1220 o Cipher Name (variable length) - Name of the cipher used
1221 in the protection of channel traffic. This name is
1222 initially decided by the creator of the channel but it
1223 may change during the life time of the channel as well.
1225 o Channel Key Length (2 bytes) - Indicates the length of the
1226 Channel Key field in the payload, not including any other
1229 o Channel Key (variable length) - The actual channel key
1230 material. This key is used as such as key material for
1236 Internet Draft SILC Packet Protocol 28 June 2000
1239 encryption function.
1242 2.3.10 Private Message Payload
1244 Private Message Payload is used to send private message between
1245 two clients (or users for that matter). The messages are sent only
1246 to the specified user and no other user inside SILC network is
1247 able to see the message. The message is protected by the session
1248 key established by the SILC Key Exchange Protocol. However,
1249 it is also possible to agree to use specific keys to protect
1250 just the private messages. See section 2.3.11 Private Message
1251 Key Payload for detailed description of how to agree to use
1254 If normal session key is used to protect the message, every
1255 server between the sender client and the receiving client needs
1256 to decrypt the packet and always re-encrypt it with the session
1257 key of the next receiver of the packet. See section Client
1258 To Client in [SILC1].
1260 When specific key is used to protect the message, servers between
1261 the sender and the receiver needs not to decrypt/re-encrypt the
1262 packet. Section 4.8.2 Client To Client in [SILC1] gives example of
1263 this scheme as well.
1265 The payload may only be sent with SILC_PACKET_PRIVATE_MESSAGE
1266 packet. It must not be sent in any other packet type. Following
1267 diagram represents the Private Message Payload.
1271 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
1272 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1273 | Nickname Length | |
1274 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1278 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1282 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1284 Figure 11: Private Message Payload
1292 Internet Draft SILC Packet Protocol 28 June 2000
1295 o Nickname Length (2 bytes) - Indicates the length of the
1296 Nickname field, not including any other field.
1298 o Nickname (variable length) - Nickname of the sender of the
1299 private message. This should not be trusted as a definite
1300 sender of the private message. The SILC Packet Header in
1301 the packet indicates the true sender of the packet and
1302 client should verify that the nickname sent here belongs
1303 to the Client ID in the SILC Packet Header. This nickname
1304 is merely provided to be displayed by the client.
1306 o Message Data (variable length) - The actual message to
1307 the client. Rest of the packet is reserved for the message
1311 2.3.11 Private Message Key Payload
1313 This payload is used to send key from client to another client that
1314 is going to be used to protect the private messages between these
1315 two clients. If this payload is not sent normal session key
1316 established by the SILC Key Exchange Protocol is used to protect
1317 the private messages.
1319 This payload may only be sent by client to another client. Server
1320 must not send this payload at any time. After sending this payload
1321 the sender of private messages must set the Private Message Key
1322 flag into SILC Packet Header.
1324 The payload may only be sent with SILC_PACKET_PRIVATE_MESSAGE_KEY
1325 packet. It must not be sent in any other packet type. Following
1326 diagram represents the Private Message Key Payload.
1330 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
1331 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1332 | Private Message Key Length | |
1333 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1335 ~ Private Message Key ~
1337 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1339 Figure 12: Private Message Key Payload
1348 Internet Draft SILC Packet Protocol 28 June 2000
1351 o Private Message Key Length (2 bytes) - Indicates the length
1352 of the Private Message Key field in the payload, not including
1355 o Private Message Key (variable length) - The actual private
1356 message key material. This key is used as such as key material
1357 for encryption function.
1360 2.3.12 Command Payload
1362 Command Payload is used to send SILC commands from client to server.
1363 Following diagram represents the Command Payload.
1367 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
1368 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1369 | SILC Command | Arguments Num | Payload Length |
1370 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1372 Figure 13: Command Payload
1375 o SILC Command (1 byte) - SILC Command identifier. This must
1376 be set to non-zero value. If zero (0) value is found in this
1377 field the packet must be discarded.
1379 o Arguments Num (1 byte) - Indicates the number of arguments
1380 associated with the command. If there are no arguments this
1381 field is set to zero (0). The arguments must follow the
1384 o Payload Length (2 bytes) - Length of the entire command
1385 payload including any command argument payloads associated
1388 See [SILC1] for detailed description of different SILC commands,
1389 their arguments and their reply messages.
1392 2.3.12.1 Command Argument Payload
1394 Command Argument Payload is used to set arguments for SILC commands.
1395 Number of arguments associated with a command are indicated by the
1396 Command Payload in the Arguments Num field. Command argument
1397 payloads may only be used with a command payload and they must
1398 always reside right after the command payload. Incorrect amount of
1404 Internet Draft SILC Packet Protocol 28 June 2000
1407 argument payloads must cause rejection of the packet. Following
1408 diagram represents the Command Argument Payload.
1412 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
1413 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1414 | Argument Num | Argument Type | Payload Length |
1415 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1419 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1421 Figure 14: Command Argument Payload
1424 o Argument Num (1 byte) - Indicates the number of this argument.
1425 For first argument this is set to 1, for second argument this
1426 is set to 2, and so forth. If incorrect value is found
1427 in this field the packet must be discarded. Value is
1428 incorrect if it is zero (0) or, for example, a third argument
1429 does not include value 3.
1431 o Argument Type (1 byte) - Indicates the type of the argument.
1432 Every command specify a number for each argument that maybe
1433 associated with the command. By using this number the receiver
1434 of the packet knows what type of argument this is. The numbers
1435 are command specific and has been defined in section SILC
1436 Commands in [SILC1]. This field makes it possible to send
1437 arguments in free order as this field is used to identify
1438 the specific type of the argument.
1440 o Payload Length (2 bytes) - Length of the argument payload data
1441 area not including the length of any other fields in the
1444 o Argument Data (variable length) - Argument data.
1447 2.3.13 Command Reply Payload
1449 Command Reply Payload is used to send replies to the commands sent
1450 by the client. The Command Reply Payload is identical to the
1451 Command Payload hence see the upper sections for Command Payload
1452 and for Command Argument Payload specifications. Command Reply
1453 message uses the Command Argument Payload as well.
1460 Internet Draft SILC Packet Protocol 28 June 2000
1463 See SILC Commands in [SILC1] for detailed description of different
1464 SILC commands, their arguments and their reply messages.
1467 2.3.14 Connection Auth Request Payload
1469 Client may send this payload to server to request the authentication
1470 method that must be used in authentication protocol. If client knows
1471 this information beforehand this payload is not necessary to be sent.
1472 Server performing authentication with another server may also send
1473 this payload to request the authentication method. If the connecting
1474 server already knows this information this payload is not necessary
1477 Server receiving this request must reply with same payload sending
1478 the mandatory authentication method. Algorithms that may be required
1479 to be used by the authentication method are the ones already
1480 established by the SILC Key Exchange protocol. See section Key
1481 Exchange Start Payload in [SILC3] for detailed information.
1483 The payload may only be sent with SILC_PACKET_CONNECTION_AUTH_REQUEST
1484 packet. It must not be sent in any other packet type. Following
1485 diagram represents the Connection Auth Request Payload.
1489 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
1490 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1491 | Connection Type | Authentication Method |
1492 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1494 Figure 15: Connection Auth Request Payload
1497 o Connection Type (2 bytes) - Indicates the type of the ID.
1498 Following connection types are defined:
1504 If any other type is found in this field the packet must be
1505 discarded and the authentication must be failed.
1507 o Authentication Method (2 bytes) - Indicates the authentication
1508 method to be used in the authentication protocol. Following
1509 authentication methods are defined:
1516 Internet Draft SILC Packet Protocol 28 June 2000
1520 1 password (mandatory)
1521 2 public key (mandatory)
1523 If any other type is found in this field the packet must be
1524 discarded and the authentication must be failed. If this
1525 payload is sent as request to receive the mandatory
1526 authentication method this field must be set to zero (0),
1527 indicating that receiver should send the mandatory
1528 authentication method. The receiver sending this payload
1529 to the requesting party, may also set this field to zero (0)
1530 to indicate that authentication is not required. In this
1531 case authentication protocol still must be started but
1532 server is most likely to respond with SILC_PACKET_SUCCESS
1536 2.3.15 New ID Payload
1538 New ID Payload is a multipurpose payload. It is used to send newly
1539 created ID's from clients and servers. When client connects to server
1540 and registers itself to the server by sending SILC_PACKET_NEW_CLIENT
1541 packet, server replies with this packet by sending the created ID for
1542 the client. Server always creates the ID for the client.
1544 This payload is also used when server tells its router that new client
1545 has registered to the SILC network. In this case the server sends
1546 the Client ID of the client to the router. Similiary when router
1547 distributes information to other routers about the client in the SILC
1548 network this payload is used.
1550 Also, when server connects to router, router uses this payload to inform
1551 other routers about new server in the SILC network. However, every
1552 server (or router) creates their own ID's thus the ID distributed by
1553 this payload is not created by the distributor in this case. Servers
1554 create their own ID's. Server registers itself to the network by sending
1555 SILC_PACKET_NEW_SERVER to the router it connected to. The case is same
1556 when router connects to another router.
1558 Hence, this payload is very important and used every time when some
1559 new entity is registered to the SILC network. Client never sends this
1560 payload. Both client and server (and router) may receive this payload.
1562 The payload may only be sent with SILC_PACKET_NEW_ID packet. It must
1563 not be sent in any other packet type. Following diagram represents the
1572 Internet Draft SILC Packet Protocol 28 June 2000
1576 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
1577 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1578 | ID Type | ID Length |
1579 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1583 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1585 Figure 16: New ID Payload
1588 o ID Type (2 bytes) - Indicates the type of the ID. See
1589 section 2.4 SILC ID Types for list of defined ID types.
1591 o ID Length (2 bytes) - Length of the ID Data area not
1592 including the length of any other fields in the payload.
1594 o ID Data (variable length) - The actual ID data.
1598 2.3.16 New ID List Payload
1600 New ID List Payload is used to distribute list of ID's usually from
1601 server to router but also from router to other routers in the network.
1602 This payload is used, for example, when server is connected to router
1603 and the server wants to distribute all of its locally connected clients
1604 and locally created channels to the router. It is convenient in this
1605 case to use this payload instead of sending all the information one
1606 by one using New ID Payload.
1608 There is no specific payload for this packet type. The packet type
1609 uses same payload as described in previous section. To form a list
1610 several payloads is put in the packet each after each. The payload
1611 is variable in length but can be calculated by calculating the ID
1612 Type field, Length field and the ID Data fields together. This forms
1613 one New ID Payload in the list.
1615 The list of payloads may only be sent with SILC_PACKET_NEW_ID_LIST
1616 packet. They must not be sent in any other packet type.
1619 2.3.17 New Client Payload
1621 When client is connected to the server, keys has been exchanged and
1622 connection has been authenticated client must register itself to the
1628 Internet Draft SILC Packet Protocol 28 June 2000
1631 server. Clients first packet after key exchange and authentication
1632 protocols must be SILC_PACKET_NEW_CLIENT. This payload tells server all
1633 the relevant information about the connected user. Server creates a new
1634 client ID for the client when received this payload and sends it to the
1635 client in New ID Payload.
1637 This payload sends username and real name of the user on the remote host
1638 which is connected to the SILC server with SILC client. The server
1639 creates the client ID according the information sent in this payload.
1640 The nickname of the user becomes the username sent in this payload.
1641 However, client should call NICK command after sending this payload to
1642 set the real nickname of the user which is then used to create new
1645 The payload may only be sent with SILC_PACKET_NEW_CLIENT packet. It
1646 must not be sent in any other packet type. Following diagram represents
1647 the New Client Payload.
1651 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
1652 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1653 | Username Length | |
1654 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1658 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1659 | Real Name Length | |
1660 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1664 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1666 Figure 17: New Client Payload
1669 o Username Length (2 bytes) - Length of the username.
1671 o Username (variable length) - The username of the user on
1672 the host where connecting to the SILC server.
1674 o Real Name Length (2 bytes) - Length of the Real Name.
1676 o Real Name (variable length) - The real name of the user
1677 on the host where connecting to the SILC server.
1684 Internet Draft SILC Packet Protocol 28 June 2000
1687 2.3.18 New Server Payload
1689 This payload is sent by server when it has completed successfully both
1690 key exchange and connection authentication protocols. The server
1691 uses this payload to register itself to the SILC network. The
1692 first packet after these key exchange and authentication protocols
1693 is SILC_PACKET_NEW_SERVER packet. The payload includes the Server ID
1694 of the server that it has created by itself. It also includes a
1695 name of the server that is associated to the Server ID.
1697 The payload may only be sent with SILC_PACKET_NEW_SERVER packet. It
1698 must not be sent in any other packet type. Following diagram represents
1699 the New Server Payload.
1703 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
1704 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1705 | Server ID Length | |
1706 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1710 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1711 | Server Name Length | |
1712 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1716 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1718 Figure 18: New Server Payload
1721 o Server ID Length (2 bytes) - Length of the ID Data area not
1722 including the length of any other fields in the payload.
1724 o Server ID Data (variable length) - The actual Server ID
1727 o Server Name Length (2 bytes) - Length of the server name.
1729 o Server Name (variable length) - The server name.
1732 2.3.19 New Channel Payload
1734 Information about newly created channel is broadcasted to all routers
1740 Internet Draft SILC Packet Protocol 28 June 2000
1743 in the SILC network by sending this packet payload. Channels are
1744 created by router of the cell. Server never creates channels unless
1745 it is a standalone server and it does not have router connection,
1746 in this case server acts as router. Normal server sends JOIN command
1747 to the router (after it has received JOIN command from client) which
1748 then processes the command and creates the channel. Client never sends
1751 The payload may only be sent with SILC_PACKET_NEW_CHANNEL packet.
1752 It must not be sent in any other packet type. Following diagram
1753 represents the New Channel Payload.
1757 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
1758 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1759 | Channel Name Length | |
1760 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1764 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1765 | Channel ID Length | |
1766 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1770 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1772 Figure 19: New Channel Payload
1776 o Channel Name Length (2 bytes) - Length of the channel name.
1778 o Channel Name (variable length) - The name of the created
1781 o Channel ID Length (2 bytes) - Length of the Channel ID.
1783 o Channel ID (variable length) - The created Channel ID.
1786 2.3.20 New Channel User Payload
1788 When client (user) joins to a channel, server must notify routers
1789 about the new user on the channel. Normal server sends this packet
1790 payload to its router which then broadcasts the packet further.
1796 Internet Draft SILC Packet Protocol 28 June 2000
1799 Router sends this packet always to its primary router. Client must
1800 not send this packet payload. The mode of the user is NONE after
1801 user has joined to the channel.
1803 The payload may only be sent with SILC_PACKET_NEW_CHANNEL_USER
1804 packet. It must not be sent in any other packet type. Following
1805 diagram represents the New Channel User Payload.
1809 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
1810 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1811 | Channel ID Length | |
1812 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1816 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1817 | Client ID Length | |
1818 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1822 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1824 Figure 20: New Channel User Payload
1827 o Channel ID Length (2 bytes) - Length of the Channel ID.
1829 o Channel ID (variable length) - The Channel ID of the channel
1830 to which the client has joined.
1832 o Client ID Length (2 bytes) - Length of the Client ID.
1834 o Client ID (variable length) - The Client ID of the client
1835 who has joined the channel.
1838 2.3.21 New Channel List Payload
1840 This payload is used to distribute list of new channels from server
1841 to routers. It might convenient to send list of new channels when
1842 existing server connects to router, instead of sending them one
1845 There is no specific payload for this packet type. The packet type
1846 uses same payload as described in 2.3.19 New Channel Payload. To form
1852 Internet Draft SILC Packet Protocol 28 June 2000
1855 a list several payloads is put in the packet each after each. The
1856 payload is variable in length but can be calculated by calculating
1857 the length of the fields together. This forms one New Channel Payload
1860 The list of payloads may only be sent with SILC_PACKET_NEW_CHANNEL_LIST
1861 packet. They must not be sent in any other packet type.
1864 2.3.22 New Channel User List Payload
1866 This payload is used to distribute list of channel users on specific
1867 channel from server to routers. It might convenient to send list of
1868 channel users when existing server connects to router, instead of
1869 sending them one by one.
1871 There is no specific payload for this packet type. The packet type
1872 uses same payload as described in 2.3.20 New Channel User Payload.
1873 To form a list several payloads is put in the packet each after each.
1874 The payload is variable in length but can be calculated by calculating
1875 the length of the fields together. This forms one New Channel User
1876 Payload in the list.
1878 The list of payloads may only be sent with packet
1879 SILC_PACKET_NEW_CHANNEL_USER_LIST. They must not be sent in any other
1883 2.3.23 Replace ID Payload
1885 This payload is used to replace old ID with new ID sent in the payload.
1886 When ID changes for some entity and the new ID is wanted to replace the
1887 old one this payload must be used. Client cannot send or receive this
1888 payload. Normal server and router server may send and receive this
1889 payload. After this packet has been sent the old ID must not be used
1892 The payload may only be sent with SILC_PACKET_REPLACE_ID packet. It must
1893 not be sent in any other packet type. Following diagram represents the
1894 Replace Payload Payload.
1908 Internet Draft SILC Packet Protocol 28 June 2000
1912 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
1913 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1914 | Old ID Type | Old ID Length |
1915 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1919 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1920 | New ID Type | New ID Length |
1921 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1925 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1927 Figure 21: Replace ID Payload
1930 o Old ID Type (2 bytes) - Indicates the type of the old ID. See
1931 section 2.4 SILC ID Types for list of defined ID types.
1933 o Old ID Length (2 bytes) - Length of the old ID Data area not
1934 including the length of any other fields in the payload.
1936 o Old ID Data (variable length) - The actual old ID data.
1938 o New ID Type (2 bytes) - Indicates the type of the new ID. See
1939 section 2.4 SILC ID Types for list of defined ID types.
1941 o New ID Length (2 bytes) - Length of the new ID Data area not
1942 including the length of any other fields in the payload.
1944 o New ID Data (variable length) - The actual new ID data.
1947 2.3.24 Remove ID Payload
1949 Remove ID payload is used to remove ID from SILC network. This is used
1950 for example when client exits SILC network. The server must in this
1951 case send this payload to notify that this ID is not valid anymore.
1952 After this has been send the old ID must not be used anymore. Client
1953 must not send this payload.
1955 The payload may only be sent with SILC_PACKET_REMOVE_ID packet. It must
1956 not be sent in any other packet type. Following diagram represents the
1957 Remove Payload Payload.
1964 Internet Draft SILC Packet Protocol 28 June 2000
1968 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
1969 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1970 | ID Type | ID Length |
1971 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1975 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1977 Figure 22: Remove ID Payload
1980 o ID Type (2 bytes) - Indicates the type of the ID to be
1981 removed. See section 2.4 SILC ID Types for list of defined
1984 o ID Length (2 bytes) - Length of the D Data area not including
1985 the length of any other fields in the payload.
1987 o ID Data (variable length) - The actual ID data to be removed.
1992 ID's are extensively used in the SILC network to associate different
1993 entities. Following ID's has been defined to be used in the SILC
1998 When ever specific ID cannot be used this is used.
2002 Server ID to associate servers. See the format of
2007 Client ID to associate clients. See the format of
2012 Channel ID to associate channels. See the format of
2020 Internet Draft SILC Packet Protocol 28 June 2000
2023 2.5 Packet Encryption And Decryption
2025 SILC packets are encrypted almost entirely. Only small part of SILC
2026 header is not encrypted as described in section 5.2 SILC Packet Header.
2027 The SILC Packet header is the first part of a packet to be encrypted
2028 and it is always encrypted with the key of the next receiver of the
2029 packet. The data payload area of the packet is always entirely
2030 encrypted and it is usually encrypted with the next receiver's key.
2031 However, there are some special packet types and packet payloads
2032 that require special encryption process. These special cases are
2033 described in the next sections. First is described the normal packet
2037 2.5.1 Normal Packet Encryption And Decryption
2039 Normal SILC packets are encrypted with the session key of the next
2040 receiver of the packet. The entire SILC Packet header and the packet
2041 data payload is is also encrypted with the same key. Padding of the
2042 packet is also encrypted always with the session key, also in special
2043 cases. Computed MAC of the packet must not be encrypted.
2045 Decryption process in these cases are straightforward. The receiver
2046 of the packet must first decrypt the SILC Packet header, or some parts
2047 of it, usually first 16 bytes of it. Then the receiver checks the
2048 packet type from the decrypted part of the header and can determine
2049 how the rest of the packet must be decrypted. If the packet type is
2050 any of the special cases described in following sections the packet
2051 decryption is special. If the packet type is not among those special
2052 packet types rest of the packet may be decrypted with the same key.
2054 Also, note that two bytes of the SILC Packet header are not encrypted
2055 thus it must be noticed in the decryption process by starting the
2056 decryption from the second byte of the header. This sets some rules
2057 to padding generation as well, see the section 2.7 Packet Padding
2060 With out a doubt, this sort of decryption processing causes some
2061 overhead to packet decryption, but never the less, is required.
2064 2.5.2 Channel Message Encryption And Decryption
2066 Channel Messages (Channel Message Payload) are always encrypted with
2067 the channel specific key. However, the SILC Packet header is not
2068 encrypted with that key. As in normal case, the header is encrypted
2069 with the key of the next receiver of the packet, who ever that might
2070 be. Note that in this case the encrypted data area is not touched
2076 Internet Draft SILC Packet Protocol 28 June 2000
2079 at all; it must not be re-encrypted with the session key.
2081 Receiver of a channel message, who ever that is, is required to decrypt
2082 the SILC Packet header to be able to even recognize the packet to be as
2083 channel message. This is same procedure as for normal SILC packets.
2084 As the receiver founds the packet to be channel message, rest of the
2085 packet processing is special. Rest of the SILC Packet header is
2086 decrypted with the same session key along with the padding of the
2087 packet. After that the packet is protected with the channel specific
2088 key and hence can be decrypted only if the receiver is the client on
2089 the channel. See section 2.7 Packet Padding Generation for more
2090 information about padding on special packets.
2092 If the receiver of the channel message is router who is routing the
2093 message to another router then it must decrypt the Channel Message
2094 payload. Between routers (that is, between cells) channel messages
2095 are protected with session keys shared between the routers. This
2096 causes another special packet processing for channel messages. If
2097 the channel message is received from another router then the entire
2098 packet, including Channel Message payload, is encrypted with the
2099 session key shared between the routers. In this case the packet
2100 decryption process is as with normal SILC packets. Hence, if the
2101 router is sending channel message to another router the Channel
2102 Message payload must have been decrypted and must be re-encrypted
2103 with the session key shared between the another router. In this
2104 case the packet encryption is as with any normal SILC packet.
2106 It must be noted that this is only when the channel messages are sent
2107 from router to another router. In all other cases the channel
2108 message encryption and decryption is as described above. This
2109 different processing of channel messages with router to router
2110 connection is because channel keys are cell specific. All cells has
2111 their own channel keys thus the channel message traveling from one
2112 cell to another must be protected as it would be any normal SILC
2116 2.5.3 Private Message Encryption And Decryption
2118 By default, private message in SILC are protected by session keys.
2119 In this case the private message encryption and decryption process is
2120 equivalent to normal packet encryption and decryption.
2122 However, private messages can be protected with private message key
2123 which causes the packet to be special packet. The procedure in this
2124 case is very much alike to channel packets. The actual private message
2125 is encrypted with the private message key and other parts of the
2126 packet is encrypted with the session key. See 2.7 Packet Padding
2132 Internet Draft SILC Packet Protocol 28 June 2000
2135 Generation for more information about padding on special packets.
2137 The difference from channel message processing is that server or router
2138 en route never decrypts the actual private message, as it does not
2139 have the key to do that. Thus, when sending packets between router
2140 the processing is same as in any other case as well; the packet's header
2141 and padding is protected by the session key and the data area is not
2144 The true receiver of the private message, client, that is, is able
2145 to decrypt the private message as it shares the key with the sender
2149 2.6 Packet MAC Generation
2151 Data integrity of a packet is protected by including a message
2152 authentication code (MAC) at the end of the packet. The MAC is computed
2153 from shared secret MAC key, that is established by the SILC Key Exchange
2154 protocol, and from the original contents of the packet. The MAC is
2155 always computed before the packet is encrypted, although after it is
2156 compressed if compression is used.
2158 The MAC is computed from entire packet. Every bit of data in the packet,
2159 including SILC Packet Header is used in the MAC computing. This way
2160 the entire packet becomes authenticated.
2162 If the packet is special packet MAC is computed from the entire packet
2163 but part of the packet may be encrypted before the MAC is computed.
2164 This is case, for example, with channel messages where the message data
2165 is encrypted with key that server may not now. In this case the MAC
2166 has been computed from the encrypted data.
2168 See [SILC1] for defined and allowed MAC algorithms.
2171 2.7 Packet Padding Generation
2173 Padding is needed in the packet because the packet is encrypted. It
2174 must always be multiple by eight (8) or multiple by the size of the
2175 cipher's block size, which ever is larger. The padding is always
2178 For normal packets the padding is added after the SILC Packet Header
2179 and between the Data Payload area. The padding for normal packets
2180 are calculated as follows:
2182 padding length = 16 - ((packet length - 2) % 16)
2188 Internet Draft SILC Packet Protocol 28 June 2000
2191 The 16 is the maximum padding allowed in SILC packet. Two (2) is
2192 subtracted from the true length of the packet because two (2) bytes
2193 is not encrypted in SILC Packet Header, see section 2.2 SILC Packet
2194 Header. Those two bytes that are not encrypted must not be calculated
2195 to the padding length.
2197 For special packets the padding calculation may be different as special
2198 packets may be encrypted differently. In these cases the encrypted
2199 data area must already be multiple by the block size thus in this case
2200 the padding is calculated only for SILC Packet Header, not for any
2201 other area of the packet. The same algorithm works in this case as
2202 well, except that the `packet length' is now the SILC Packet Header
2203 length. In this case, as well, two (2) is subtracted from the
2206 The padding must be random data, preferably, generated by
2207 cryptographically strong random number generator.
2210 2.8 Packet Compression
2212 SILC Packets may be compressed. In this case the data payload area
2213 is compressed and all other areas of the packet must remain as they
2214 are. After compression is performed for the data area, the length
2215 field of Packet Header must be set to the compressed length of the
2218 The compression must always be applied before encryption. When
2219 the packet is received and decrypted the data area must be decompressed.
2220 Note that the true sender of the packet must apply the compression and
2221 the true receiver of the packet must apply the decompression. Any
2222 server or router en route must not decompress the packet.
2227 The sender of the packet must assemble the SILC Packet Header with
2228 correct values. It must set the Source ID of the header as its own
2229 ID. It must also set the Destination ID of the header to the true
2230 destination. If the destination is client it will be Client ID, if
2231 it is server it will be Server ID and if it is channel it will be
2234 If the sender wants to compress the packet it must apply the
2235 compression now. Sender must also compute the padding as described
2236 in above sections. Then sender must compute the MAC of the packet.
2238 Then sender encrypts the packet as has been described in above
2244 Internet Draft SILC Packet Protocol 28 June 2000
2247 sections according whether the packet is normal packet or special
2248 packet. The computed MAC must not be encrypted.
2251 2.10 Packet Reception
2253 On packet reception the receiver must check that all fields in the
2254 SILC Packet Header are valid sain. It must check the flags of the
2255 header and act accordingly. It must also check the MAC of the packet
2256 and if it is to be failed the packet must be discarded. Also if the
2257 header of the packet includes any bad fields the packet must be
2260 See above sections on the decryption process of the received packet.
2262 The receiver must also check that the ID's in the header are valid
2263 ID's. Unsupported ID types or malformed ID's must cause packet
2264 rejection. The padding on the reception is always ignored.
2266 The receiver must also check the packet type and start parsing the
2267 packet according to the type. However, note the above sections on
2268 special packet types and their parsing.
2271 2.11 Packet Broadcasting
2273 SILC packets may be broadcasted in SILC network. However, only router
2274 server may send or receive broadcast packets. Client and normal server
2275 must not send broadcast packets and they must ignore broadcast packets
2276 if they receive them. Broadcast packets are sent by setting Broadcast
2277 flag to the SILC packet header.
2279 Broadcasting packets means that the packet is sent to all routers in
2280 the SILC network, except to the router that sent the packet. The router
2281 receiving broadcast packet must send the packet to its primary route.
2282 The fact that SILC routers may have several router connections may
2283 cause problems, such as race conditions inside the SILC network, if
2284 care is not taken when broadcasting packets. Router must not send
2285 the broadcast packet to any other route except to its primary route.
2287 If the primary route of the router is the original sender of the packet
2288 the packet must not be sent to the primary route. This may happen
2289 if router has several router connections and some other router uses
2290 the router as its primary route.
2292 Routers use broadcast packets to broadcast for example information
2293 about newly registered clients, servers, channels etc. so that all the
2294 routers may keep these informations up to date.
2300 Internet Draft SILC Packet Protocol 28 June 2000
2305 Routers are the primary entities in the SILC network that takes care
2306 of packet routing. However, normal servers routes packets as well, for
2307 example, when they are routing channel message to the local clients.
2308 Routing is quite simple as every packet tells the true origin and the
2309 true destination of the packet.
2311 It is still recommended for routers that has several routing connections
2312 to create route cache for those destinations that has faster route than
2313 the router's primary route. This information is available for the router
2314 when other router connects to the router. The connecting party then
2315 sends all of its locally connected clients, server and channels. These
2316 informations helps to create the route cache. Also, when new channels
2317 are created to a cell its information is broadcasted to all routers
2318 in the network. Channel ID's are based on router's ID thus it is easy
2319 to create route cache based on these informations. If faster route for
2320 destination does not exist in router's route cache the packet must be
2321 routed to the primary route (default route).
2323 For server who receives a packet to be routed to its locally connected
2324 client the server must check whether the particular packet type is
2325 allowed to be routed to the client. Not all packets may be sent by
2326 some odd entity to client that is indirectly connected to the sender.
2327 See section 2.3 SILC Packet Types and paragraph about indirectly connected
2328 entities and sending packets to them. The section mentions the packets
2329 that may be sent to indirectly connected entities. It is clear that some
2330 server cannot send, for example, disconnect packet to client that is not
2331 directly connected to the server.
2334 2.13 Packet Tunneling
2336 Tunneling is a feature that is available in SILC protocol. Tunneling
2337 means that extra SILC Packet Header is applied to the original packet
2338 and thus hiding the original packet entirely. There can be some
2339 interesting applications using tunneling, such as, using ID's based on
2340 private network IP addresses inside in the tunneled packet. This can
2341 open many interesting features relating to connecting to private network
2342 from the Internet with SILC and many more. However, this feature is
2343 optional currently in SILC as there does not exist thorough analysis of
2344 this feature. It is with out a doubt that there will be many more
2345 applications that has not yet been discovered. Thus, it is left
2346 to Internet Community to investigate the use of tunneling in SILC
2347 protocol. This document is updated according those investigations
2348 and additional documents on the issue may be written.
2356 Internet Draft SILC Packet Protocol 28 June 2000
2359 3 Security Considerations
2361 Security is central to the design of this protocol, and these security
2362 considerations permeate the specification.
2367 [SILC1] Riikonen, P., "Secure Internet Live Conferencing (SILC),
2368 Protocol Specification", Internet Draft, June 2000.
2370 [SILC3] Riikonen, P., "SILC Key Exchange and Authentication
2371 Protocols", Internet Draft, June 2000.
2373 [IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
2376 [SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
2379 [PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
2382 [SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
2385 [PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
2386 Infrastructure, Certificate and CRL Profile", RFC 2459,
2389 [Schneier] Schneier, B., "Applied Cryptography Second Edition",
2390 John Wiley & Sons, New York, NY, 1996.
2392 [Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
2395 [OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
2396 RFC 2412, November 1998.
2398 [ISAKMP] Maughan D., et al, "Internet Security Association and
2399 Key Management Protocol (ISAKMP)", RFC 2408, November
2402 [IKE] Harkins D., and Carrel D., "The Internet Key Exhange
2403 (IKE)", RFC 2409, November 1998.
2405 [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
2406 Authentication", RFC 2104, February 1997.
2412 Internet Draft SILC Packet Protocol 28 June 2000
2422 EMail: priikone@poseidon.pspt.fi
projects / runtime.git / blob