8 .ds RF FORMFEED[Page %]
12 .ds CH Secure Internet Live Conferencing
17 Network Working Group P. Riikonen
19 draft-riikonen-silc-spec-00.txt 28 June 2000
25 Secure Internet Live Conferencing (SILC),
26 Protocol Specification
31 This document is an Internet-Draft. Internet-Drafts are working
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48 The distribution of this memo is unlimited.
54 This memo describes a Secure Internet Live Conferencing (SILC)
55 protocol which provides secure conferencing services over insecure
56 network channel. SILC is IRC [IRC] like protocol, however, it is
57 not equivalent to IRC and does not support IRC. Strong cryptographic
58 methods are used to protect SILC packets inside SILC network. Two
59 other Internet Drafts relates very closely to this memo; SILC Packet
60 Protocol [SILC2] and SILC Key Exchange and Authentication Protocols
74 1 Introduction .................................................. 3
75 2 SILC Concepts ................................................. 3
76 2.1 SILC Network Topology ..................................... 4
77 2.2 Communication Inside a Cell ............................... 5
78 2.3 Communication in the Network .............................. 6
79 2.4 Channel Communication ..................................... 7
80 3 SILC Specification ............................................ 7
81 3.1 Client .................................................... 7
82 3.1.1 Client ID ........................................... 8
83 3.2 Server .................................................... 9
84 3.2.1 Server's Local ID List .............................. 9
85 3.2.2 Server ID ........................................... 10
86 3.2.3 SILC Server Ports ................................... 11
87 3.3 Router .................................................... 11
88 3.3.1 Router's Local ID List .............................. 11
89 3.3.2 Router's Global ID List ............................. 12
90 3.3.3 Router's Server ID .................................. 13
91 3.4 Channels .................................................. 13
92 3.4.1 Channel ID .......................................... 14
93 3.5 Operators ................................................. 14
94 3.6 SILC Commands ............................................. 15
95 3.7 SILC Packets .............................................. 15
96 3.8 Packet Encryption ......................................... 16
97 3.8.1 Determination of the Source and the Destination ..... 16
98 3.8.2 Client To Client .................................... 17
99 3.8.3 Client To Channel ................................... 18
100 3.8.4 Server To Server .................................... 19
101 3.9 Key Exchange And Authentication ........................... 19
102 3.10 Algorithms ............................................... 19
103 3.10.1 Ciphers ............................................ 19
104 3.10.2 Public Key Algorithms .............................. 20
105 3.10.3 MAC Algorithms ..................................... 20
106 3.10.4 Compression Algorithms ............................. 21
107 3.11 SILC Public Key .......................................... 21
108 4 SILC Procedures ............................................... 24
109 4.1 Creating Client Connection ................................ 24
110 4.2 Creating Server Connection ................................ 25
111 4.3 Joining to a Channel ...................................... 26
112 4.4 Channel Key Generation .................................... 27
113 4.5 Private Message Sending and Reception ..................... 27
114 4.6 Private Message Key Generation ............................ 28
115 4.7 Channel Message Sending and Reception ..................... 29
116 4.8 Session Key Regeneration .................................. 29
117 4.9 Command Sending and Reception ............................. 29
118 5 SILC Commands ................................................. 30
119 5.1 SILC Commands Syntax ...................................... 30
120 5.2 SILC Commands List ........................................ 32
121 5.3 SILC Command Status Types ................................. 53
122 5.3.1 SILC Command Status Payload ......................... 53
123 5.3.2 SILC Command Status List ............................ 54
124 6 Security Considerations ....................................... 59
125 7 References .................................................... 59
126 8 Author's Address .............................................. 60
133 Figure 1: SILC Network Topology
134 Figure 2: Communication Inside cell
135 Figure 3: Communication Between Cells
136 Figure 4: SILC Public Key
137 Figure 5: SILC Command Status Payload
143 This document describes a Secure Internet Live Conferencing (SILC)
144 protocol which provides secure conferencing services over insecure
145 network channel. SILC is IRC [IRC] like protocol, however, it is
146 not equivalent to IRC and does not support IRC.
148 Strong cryptographic methods are used to protect SILC packets inside
149 SILC network. Two other Internet Drafts relates very closely to this
150 memo; SILC Packet Protocol [SILC2] and SILC Key Exchange and
151 Authentication Protocols [SILC3].
153 The protocol uses extensively packets as conferencing protocol
154 requires message and command sending. The SILC Packet Protocol is
155 described in [SILC2] and should be read to fully comprehend this
156 document and protocol. [SILC2] also describes the packet encryption
157 and decryption in detail.
159 The security of SILC protocol and for any security protocol for that
160 matter is based on strong and secure key exchange protocol. The SILC
161 Key Exchange protocol is described in [SILC3] along with connection
162 authentication protocol and should be read to fully comprehend this
163 document and protocol.
165 The SILC protocol has been developed to work on TCP/IP network
166 protocol, although it could be made to work on other network protocols
167 with only minor changes. However, it is recommended that TCP/IP
168 protocol is used under SILC protocol. Typical implementation would
169 be made in client-server model.
175 This section describes various SILC protocol concepts that forms the
176 actual protocol, and in the end, the actual SILC network. The mission
177 of the protocol is to deliver messages from clients to other clients
178 through routers and servers in secure manner. The messages may also
179 be delivered from one client to many clients forming a group, also
182 This section does not focus to security issues, instead basic network
183 concepts are introduced to make the topology of the SILC network
188 2.1 SILC Network Topology
190 SILC network is a cellular network as opposed to tree style network
191 topology. The rationale for this is to have servers that can perform
192 specific kind of tasks what other servers cannot perform. This leads
193 to two kinds of servers; normal SILC servers and SILC routers.
195 A difference between normal server and router server is that routers
196 knows everything about everything in the network. They also do the
197 actual routing of the messages to the correct receiver. Normal servers
198 knows only about local information and nothing about global information.
199 This makes the network faster as there are less servers that needs to
200 keep global information up to date at all time.
202 This, on the other hand, leads to cellular like network, where routers
203 are in the centrum on the cell and servers are connected to the router.
205 Following diagram represents SILC network topology.
225 ---- ---- ---- ---- ---- ----
226 | S8 | S5 | S4 | | S7 | S5 | S6 |
227 ----- ---- ----- ----- ---- -----
228 | S7 | S/R1 | S2 | --- | S8 | S/R2 | S4 |
229 ---- ------ ---- ---- ------ ----
230 | S6 | S3 | S1 | | S1 | S3 | S2 | ---- ----
231 ---- ---- ---- ---- ---- ---- | S3 | S1 |
232 Cell 1. \\ Cell 2. | \\____ ----- -----
234 ---- ---- ---- ---- ---- ---- ---- ------
235 | S7 | S4 | S2 | | S1 | S3 | S2 | | S2 | S5 |
236 ----- ---- ----- ----- ---- ----- ---- ----
237 | S6 | S/R3 | S1 | --- | S4 | S/R5 | S5 | Cell 4.
238 ---- ------ ---- ---- ------ ----
239 | S8 | S5 | S3 | | S6 | S7 | S8 | ... etc ...
240 ---- ---- ---- ---- ---- ----
245 Figure 1: SILC Network Topology
248 A cell is formed when a server or servers connect to one router. In
249 SILC network normal server cannot directly connect to other normal
250 server. Normal server may only connect to SILC router which then
251 routes the messages to the other servers in the cell. Router servers
252 on the other hand may connect to other routers to form the actual SILC
253 network, as seen in above figure. However, router is also normal SILC
254 server; clients may connect to it the same way as to normal SILC
255 servers. Normal server also cannot have active connections to more
256 than one router. Normal server cannot be connected to two different
257 cells. Router servers, on the other hand, may have as many router to
258 router connections as needed.
260 There are many issues in this network topology that needs to be careful
261 about. Issues like the size of the cells, the number of the routers in
262 the SILC network and the capacity requirements of the routers. These
263 issues should be discussed in the Internet Community and additional
264 documents on the issue will be written.
268 2.2 Communication Inside a Cell
270 It is always guaranteed that inside a cell message is delivered to the
271 recipient with at most two server hops. Client who is connected to
272 server in the cell and is talking on channel to other client connected
273 to other server in the same cell, will have its messages delivered from
274 its local server first to the router of the cell, and from the router
275 to the other server in the cell. Following diagram represents this
290 Figure 2: Communication Inside cell
293 Example: Client 1. connected to Server 1. message sent to
294 Client 4. connected to Server 2. travels from Server 1.
295 first to Router which routes the message to Server 2.
296 which then sends it to the Client 4. All the other
297 servers in the cell will not see the routed message.
300 If client is connected directly to the router, as router is also normal
301 SILC server, the messages inside the cell are always delivered only with
302 one server hop. If clients communicating with each other are connected
303 to the same server, no router interaction is needed. This is the optimal
304 situation of message delivery in the SILC network.
308 2.3 Communication in the Network
310 If the message is destined to server that does not belong to local cell
311 the message is routed to the router server to which the destination
312 server belongs, if the local router is connected to destination router.
313 If there is no direct connection to the destination router, the local
314 router routes the message to its primary route. Following diagram
315 represents message sending between cells.
320 1 --- S1 S4 --- 5 S2 --- 1
321 S/R - - - - - - - - S/R
331 Figure 3: Communication Between Cells
334 Example: Client 5. connected to Server 4. in Cell 1. message sent
335 to Client 2. connected to Server 1. in Cell 2. travels
336 from Server 4. to Router which routes the message to
337 Router in Cell 2, which then routes the message to
338 Server 1. All the other servers and routers in the
339 network will not see the routed message.
342 The optimal case of message delivery from client point of view is
343 when clients are connected directly to the routers and the messages
344 are delivered from one router to the other router.
348 2.4 Channel Communication
350 Messages may be sent to group of clients as well. Sending messages to
351 many clients works the same way as sending messages point to point, from
352 message delivery point of view. Security issues are another matter
353 which are not discussed in this section.
355 Router server handles the message routing to multiple recipients. If
356 any recipient is not in the same cell as the sender the messages are
359 Server distributes the channel message to its local clients who are
360 joined to the channel. Also, router distributes the message to its
361 local clients on the channel.
365 3. SILC Specification
367 This section describes the SILC protocol. However, [SILC2] and
368 [SILC3] describes other important protocols that are part of this SILC
369 specification and must be read.
375 A client is a piece of software connecting to SILC server. SILC client
376 cannot be SILC server. Purpose of clients is to provide the user
377 interface of the SILC services for end user. Clients are distinguished
378 from other clients by unique Client ID. Client ID is a 128 bit ID that
379 is used in the communication in the SILC network. The client ID is
380 based on the nickname selected by the user. User uses logical nicknames
381 in communication which are then mapped to the corresponding Client ID.
382 Client ID's are low level identifications and must not be seen by the
385 Clients provide other information about the end user as well. Information
386 such as the nickname of the user, username and the hostname of the end
387 user and user's real name. See section 3.2 Server for information of
388 the requirements of keeping this information.
390 The nickname selected by the user is not unique in the SILC network.
391 There can be 2^8 same nicknames for one IP address. As for comparison to
392 IRC [IRC] where nicknames are unique this is a fundamental difference
393 between SILC and IRC. This causes the server names to be used along
394 with the nicknames to identify specific users when sending messages.
395 This feature of SILC makes IRC style nickname-wars obsolete as no one
396 owns their nickname; there can always be someone else with the same
397 nickname. Another difference is that there are no limit of the length
398 of the nickname in the SILC.
404 Client ID is used to identify users in the SILC network. The Client ID
405 is unique to the extent that there can be 2^128 different Client ID's.
406 Collisions are not expected to happen. The Client ID is defined as
410 128 bit Client ID based on IPv4 addresses:
412 32 bit ServerID IP address (bits 1-32)
414 88 bit Truncated MD5 hash value of the nickname
416 o Server ID IP address - Indicates the server where this
417 client is coming from. The IP address hence equals the
418 server IP address where to the client has connected.
420 o Random number - Random number to further unify the
421 Client ID. This makes it possible to have 2^8 same
422 nicknames from the same server IP address.
424 o MD5 hash - MD5 hash value of the nickname is truncated
425 taking 88 bits from the start of the hash value. This
426 hash value is used to search the user's Client ID from
430 Collisions could occur when more than 2^8 clients using same nickname
431 from the same server IP address is connected to the SILC network.
432 Server must be able to handle this situation by refusing to accept
433 anymore of that nickname.
435 Another possible collision may happen with the truncated hash value of
436 the nickname. It could be possible to have same truncated hash value for
437 two different nicknames. However, this is not expected to happen nor
438 cause any problems if it would occur. Nicknames are usually logical and
439 it is unlikely to have two distinct logical nicknames produce same
440 truncated hash value.
446 Servers are the most important parts of the SILC network. They form the
447 basis of the SILC, providing a point to which clients may connect to.
448 There are two kinds of servers in SILC; normal servers and router servers.
449 This section focuses on the normal server and router server is described
450 in the section 3.3 Router.
452 Normal servers may not directly connect to other normal server. Normal
453 servers may only directly connect to router server. If the message sent
454 by the client is destined outside the local server it is always sent to
455 the router server for further routing. Server may only have one active
456 connection to router on same port. Normal server may not connect to other
457 cell's router except in situations where its cell's router is unavailable.
459 Servers and routers in the SILC network are considered to be trusted.
460 With out a doubt, servers that are set to work on ports above 1023 are
461 not considered to be trusted. Also, the service provider acts important
462 role in the server's trustworthy.
466 3.2.1 Server's Local ID List
468 Normal server keeps various information about the clients and their end
469 users connected to it. Every normal server must keep list of all locally
470 connected clients, Client ID's, nicknames, usernames and hostnames and
471 user's real name. Normal servers only keeps local information and it
472 does not keep any global information. Hence, normal servers knows only
473 about their locally connected clients. This makes servers efficient as
474 they don't have to worry about global clients. Server is also responsible
475 of creating the Client ID's for their clients.
477 Normal server also keeps information about locally created channels and
487 Hence, local list for normal server includes:
490 server list - Router connection
498 client list - All clients in server
506 channel list - All channels in server
509 o Client ID's on channel
510 o Client ID modes on channel
519 Servers are distinguished from other servers by unique 64 bit Server ID.
520 The Server ID is used in the SILC to route messages to correct servers.
521 Server ID's also provide information for Client ID's, see section 3.1.1
522 Client ID. Server ID is defined as follows.
525 64 bit Server ID based on IPv4 addresses:
527 32 bit IP address of the server
531 o IP address of the server - This is the real IP address of
534 o Port - This is the port the server is binded to.
536 o Random number - This is used to further unify the Server ID.
539 Collisions are not expected to happen in any conditions. The Server ID
540 is always created by the server itself and server is resposible of
541 distributing it to the router.
545 3.2.3 SILC Server Ports
547 SILC uses currently TCP port 334 on SILC network. However, this is not
548 official port assigned for SILC. Official port has been requested by
551 If there are needs to create new SILC networks in the future the port
552 numbers must be officially assigned by the IANA. Most convenience case
553 would be to assign port numbers upwards from 334.
555 Server on network above privileged ports (>1023) should not be trusted
556 as they could have been set up by untrusted party.
562 Router server in SILC network is responsible for keeping the cell together
563 and routing messages to other servers and to other routers. Router server
564 is also a normal server thus clients may connect to it as it would be
565 just normal SILC server.
567 However, router servers has a lot of important tasks that normal servers
568 do not have. Router server knows everything about everything in the SILC.
569 They know all clients currently on SILC, all servers and routers and all
570 channels in SILC. Routers are the only servers in SILC that care about
571 global information and keeping them up to date at all time. And, this
572 is what they must do.
576 3.3.1 Router's Local ID List
578 Router server as well must keep local list of connected clients and
579 locally created channels. However, this list is extended to include all
580 the informations of the entire cell, not just the server itself as for
583 However, on router this list is a lot smaller since routers do not keep
584 information about user's nickname, username and hostname and real name
585 since these are not needed by the router. Router keeps only information
592 Hence, local list for router includes:
595 server list - All servers in the cell
602 client list - All clients in the cell
605 channel list - All channels in the cell
607 o Client ID's on channel
608 o Client ID modes on channel
613 Note that locally connected clients and other information include all the
614 same information as defined in section section 3.2.1 Server's Local ID
619 3.3.2 Router's Global ID List
621 Router server must also keep global list. Normal servers do not have
622 global list as they know only about local information. Global list
623 includes all the clients on SILC, their Client ID's, all created channels
624 and their Channel ID's and all servers and routers on SILC and their
625 Server ID's. That is said, global list is for global information and the
626 list must not include the local information already on the router's local
629 Note that the global list does not include information like nicknames,
630 usernames and hostnames or user's real names. Router does not keep
631 these informations as they are not needed by the router. This
632 information is available from the client's server which maybe queried
635 Hence, global list includes:
638 server list - All servers in SILC
644 client list - All clients in SILC
647 channel list - All channels in SILC
649 o Client ID's on channel
650 o Client ID modes on channel
655 3.3.3 Router's Server ID
657 Router's Server ID's are equivalent to normal Server ID's. As routers
658 are normal servers as well same types of ID's applies for routers as well.
659 Thus, see section 3.2.2 Server ID. Server ID's for routers are always
660 created by the remote router where the router is connected to.
666 A channel is a named group of one or more clients which will all receive
667 messages addressed to that channel. The channel is created when first
668 client requests JOIN command to the channel, and the channel ceases to
669 exist when the last client leaves it. When channel exists, any client
670 can reference it using the name of the channel.
672 Channel names are unique although the real uniqueness comes from 64 bit
673 Channel ID that unifies each channel. However, channel names are still
674 unique and no two global channels with same name may exist. Channel name
675 is a string which begins with `#' character. There is no limit on the
676 length of the channel name. Channel names may not contain any spaces
677 (` '), any non-printable ASCII characters, commas (`,') and wildcard
680 Channels can have operators that can administrate the channel and
681 operate all of its modes. Following operators on channel exist on SILC
685 o Channel founder - When channel is created the joining client becomes
686 channel founder. Channel founder is channel operator with some more
687 privileges. Basically, channel founder can fully operate the channel
688 and all of its modes. The privileges are limited only to the particular
689 channel. There can be only one channel founder per channel. Channel
690 founder supersedes channel operator's privileges.
692 Channel founder privileges cannot be removed by any other operator on
693 channel. When channel founder leaves the channel there is no channel
694 founder on the channel. Channel founder also cannot be removed by
695 force from the channel.
697 o Channel operator - When client joins to channel that has not existed
698 previously it will become automatically channel operator (and channel
699 founder discussed above). Channel operator is able administrate the
700 channel, set some modes on channel, remove a badly behaving client from
701 the channel and promote other clients to become channel operator.
702 The privileges are limited only to the particular channel.
704 Normal channel user may be promoted (opped) to channel operator
705 gaining channel operator privileges. Channel founder or other channel
706 operator may also demote (deop) channel operator to normal channel
714 Channels are distinguished from other channels by unique Channel ID.
715 The Channel ID is a 64 bit ID and collisions are not expected to happen
716 in any conditions. Channel names are just for logical use of channels.
717 The Channel ID is created by the server where the channel is created.
718 The Channel ID is defined as follows.
721 64 bit Channel ID based on IPv4 addresses:
723 32 bit Router's Server ID IP address (bits 1-32)
724 16 bit Router's Server ID port (bits 33-48)
727 o Router's Server ID IP address - Indicates the IP address of
728 the router of the cell where this channel is created. This is
729 taken from the router's Server ID. This way SILC router knows
730 where this channel resides in the SILC network.
732 o Router's Server ID port - Indicates the port of the channel on
733 the server. This is taken from the router's Server ID.
735 o Random number - To further unify the Channel ID. This makes
736 sure that there are no collisions. This also means that
737 in a cell there can be 2^16 channels.
744 Operators are normal users with extra privileges to their server or
745 router. Usually these people are SILC server and router administrators
746 that take care of their own server and clients on them. The purpose of
747 operators is to administrate the SILC server or router. However, even
748 an operator with highest privileges is not able to enter invite-only
749 channel, to gain access to the contents of a encrypted and authenticated
750 packets traveling in the SILC network or to gain channel operator
751 privileges on public channels without being promoted. They have the
752 same privileges as everyone else except they are able to administrate
753 their server or router.
759 Commands are very important part on SILC network especially for client
760 which uses commands to operate on the SILC network. Commands are used
761 to set nickname, join to channel, change modes and many other things.
763 Client usually sends the commands and server replies by sending a reply
764 packet to the command. Server may also send commands usually to serve
765 the original client's request. However, server may not send command
766 to client and there are some commands that server must not send.
768 Note that the command reply is usually sent only after client has sent
769 the command request but server is allowed to send command reply packet
770 to client even if client has not requested the command. Client may,
771 however, choose not to accept the command reply, but there are some
772 command replies that the client should accept. Example of a such
773 command reply is reply to SILC_COMMAND_CMODE command that the server
774 uses to distribute the channel mode on all clients on the channel
775 when the mode has changed.
777 It is expected that some of the commands may be miss-used by clients
778 resulting various problems on the server side. Every implementation
779 should assure that commands may not be executed more than once, say,
780 in two (2) seconds. This should be sufficient to prevent the miss-use
783 SILC commands are described in section 5 SILC Commands.
789 Packets are naturally the most important part of the protocol and the
790 packets are what actually makes the protocol. Packets in SILC network
791 are always encrypted using, usually, the shared secret session key
792 or some other key, for example, channel key, when encrypting channel
793 messages. The SILC Packet Protocol is a wide protocol and is described
794 in [SILC2]. This document does not define or describe details of
801 3.8 Packet Encryption
803 All packets passed in SILC network must be encrypted. This section
804 defines how packets must be encrypted in the SILC network. The detailed
805 description of the actual encryption process of the packets are
806 described in [SILC2].
808 Client and its server shares secret symmetric session key which is
809 established by the SILC Key Exchange Protocol, described in [SILC3].
810 Every packet sent from client to server, with exception of packets for
811 channels, are encrypted with this session key.
813 Channels has their own key that are shared by every client on the channel.
814 However, the channel keys are cell specific thus one cell does not know
815 the channel key of the other cell, even if that key is for same channel.
816 Channel key is also known by the routers and all servers that has clients
817 on the channel. However, channels may have channel private keys that
818 are entirely local setting for client. All clients on the channel must
819 know the channel private key before hand to be able to talk on the
820 channel. In this case, no server or router knows the key for channel.
822 Server shares secret symmetric session key with router which is
823 established by the SILC Key Exchange Protocol. Every packet passed from
824 server to router, with exception of packets for channels, are encrypted
825 with the shared session key. Same way, router server shares secret
826 symmetric key with its primary route. However, every packet passed
827 from router to other router, including packets for channels, are
828 encrypted with the shared session key. Every router connection has
829 their own session keys.
833 3.8.1 Determination of the Source and the Destination
835 The source and the destination of the packet needs to be determined
836 to be able to route the packets to correct receiver. This information
837 is available in the SILC Packet Header which is included in all packets
838 sent in SILC network. The SILC Packet Header is described in [SILC2].
840 The header is always encrypted with the session key who is next receiver
841 of the packet along the route. The receiver of the packet, for example
842 a router along the route, is able to determine the sender and the
843 destination of the packet by decrypting the SILC Packet Header and
844 checking the ID's attached to the header. The ID's in the header will
845 tell to where the packet needs to be sent and where it is coming from.
847 The header in the packet does not change during the routing of the
848 packet. The original sender, for example client, assembles the packet
849 and the packet header and server or router between the sender and the
850 receiver must not change the packet header.
852 Note that the packet and the packet header may be encrypted with
853 different keys. For example, packets to channels are encrypted with
854 the channel key, however, the header is encrypted with the session key
855 as described above. However, the header and the packet may be encrypted
856 with same key. This is case, for example, with command packets.
860 3.8.2 Client To Client
862 Process of message delivery and encryption from client to another
863 client is as follows.
865 Example: Private message from client to another client on different
866 servers. Clients do not share private message delivery
867 keys; normal session keys are used.
869 o Client 1. sends encrypted packet to its server. The packet is
870 encrypted with the session key shared between client and its
873 o Server determines the destination of the packet and decrypts
874 the packet. Server encrypts the packet with session key shared
875 between the server and its router, and sends the packet to the
878 o Router determines the destination of the packet and decrypts
879 the packet. Router encrypts the packet with session key
880 shared between the router and the destination server, and sends
881 the packet to the server.
883 o Server determines the client to which the packet is destined
884 to and decrypts the packet. Server encrypts the packet with
885 session key shared between the server and the destination client,
886 and sends the packet to the client.
888 o Client 2. decrypts the packet.
891 Example: Private message from client to another client on different
892 servers. Clients has established secret shared private
893 message delivery key with each other and that is used in
894 the message encryption.
896 o Client 1. sends encrypted packet to its server. The packet is
897 encrypted with the private message delivery key shared between
900 o Server determines the destination of the packet and sends the
901 packet to the router.
903 o Router determines the destination of the packet and sends the
904 packet to the server.
906 o Server determines the client to which the packet is destined
907 to and sends the packet to the client.
909 o Client 2. decrypts the packet with the secret shared key.
912 If clients share secret key with each other the private message
913 delivery is much simpler since servers and routers between the
914 clients do not need to decrypt and re-encrypt the packet.
916 The process for clients on same server is much simpler as there are
917 no need to send the packet to the router. The process for clients
918 on different cells is same as above except that the packet is routed
919 outside the cell. The router of the destination cell routes the
920 packet to the destination same way as described above.
924 3.8.3 Client To Channel
926 Process of message delivery from client on channel to all the clients
929 Example: Channel of four users; two on same server, other two on
930 different cells. Client sends message to the channel.
932 o Client 1. encrypts the packet with channel key and sends the
933 packet to its server.
935 o Server determines local clients on the channel and sends the
936 packet to the Client on the same server. Server then sends
937 the packet to its router for further routing.
939 o Router determines local clients on the channel, if found
940 sends packet to the local clients. Router determines global
941 clients on the channel and sends the packet to its primary
942 router or fastest route.
944 o (Other router(s) do the same thing and sends the packet to
947 o Server determines local clients on the channel and sends the
948 packet to the client.
950 o All clients receiving the packet decrypts the packet.
954 3.8.4 Server To Server
956 Server to server packet delivery and encryption is described in above
957 examples. Router to router packet delivery is analogous to server to
958 server. However, some packets, such as channel packets, are processed
959 differently. These cases are described later in this document and
960 more in detail in [SILC2].
964 3.9 Key Exchange And Authentication
966 Key exchange is done always when for example client connects to server
967 but also when server and router and router and router connects to each
968 other. The purpose of key exchange protocol is to provide secure key
969 material to be used in the communication. The key material is used to
970 derive various security parameters used to secure SILC packets. The
971 SILC Key Exchange protocol is described in detail in [SILC3].
973 Authentication is done after key exchange protocol has been successfully
974 completed. The purpose of authentication is to authenticate for example
975 client connecting to the server. However, Usually clients are accepted
976 to connect to server without explicit authentication. Servers are
977 required use authentication protocol when connecting. The authentication
978 may be based on passphrase (pre-shared-secret) or public key. The
979 connection authentication protocol is described in detail in [SILC3].
985 This section defines all the allowed algorithms that can be used in
986 the SILC protocol. This includes mandatory cipher, mandatory public
987 key algorithm and MAC algorithms.
993 Cipher is the encryption algorithm that is used to protect the data
994 in the SILC packets. See [SILC2] of the actual encryption process and
995 definition of how it must be done. SILC has a mandatory algorithm that
996 must be supported in order to be compliant with this protocol.
1003 Following ciphers are defined in SILC protocol:
1006 blowfish-cbc Blowfish in CBC mode (mandatory)
1007 twofish-cbc Twofish in CBC mode (optional)
1008 rc6-cbc RC6 in CBC mode (optional)
1009 rc5-cbc RC5 in CBC mode (optional)
1010 mars-cbc Mars in CBC mode (optional)
1011 none No encryption (optional)
1015 All algorithms must use minimum of 128 bit key, by default. Several
1016 algorithms, however, supports longer keys and it is recommended to use
1017 longer keys if they are available.
1019 Algorithm none does not perform any encryption process at all and
1020 thus is not recommended to be used. It is recommended that no client
1021 or server implementation would accept none algorithms except in special
1024 Additional ciphers may be defined to be used in SILC by using the
1025 same name format as above.
1029 3.10.2 Public Key Algorithms
1031 Public keys are used in SILC to authenticate entities in SILC network
1032 and to perform other tasks related to public key cryptography. The
1033 public keys are also used in the SILC Key Exchange protocol [SILC3].
1035 Following public key algorithms are defined in SILC protocol:
1042 Both of the algorithms are described in [Scheneir] and [Menezes].
1044 Additional public key algorithms may be defined to be used in SILC.
1048 3.10.3 MAC Algorithms
1050 Data integrity is protected by computing a message authentication code
1051 (MAC) of the packet data. See [SILC2] for details how to compute the
1058 Following MAC algorithms are defined in SILC protocol:
1061 hmac-sha1 HMAC-SHA1, length = 20 (mandatory)
1062 hmac-md5 HMAC-MD5, length = 16 (optional)
1063 none No MAC (optional)
1066 The none MAC is not recommended to be used as the packet is not
1067 authenticated when MAC is not computed. It is recommended that no
1068 client or server would accept none MAC except in special debugging
1071 The HMAC algorithm is described in [HMAC] and hash algorithms that
1072 are used as part of the HMACs are described in [Scheneir] and in
1075 Additional MAC algorithms may be defined to be used in SILC.
1079 3.10.4 Compression Algorithms
1081 SILC protocol supports compression that may be applied to unencrypted
1082 data. It is recommended to use compression on slow links as it may
1083 significantly speed up the data transmission. By default, SILC does not
1084 use compression which is the mode that must be supported by all SILC
1087 Following compression algorithms are defined:
1090 none No compression (mandatory)
1091 zlib GBU ZLIB (LZ77) compression (optional)
1094 Additional compression algorithms may be defined to be used in SILC.
1098 3.11 SILC Public Key
1100 This section defines the type and format of the SILC public key. All
1101 implementations must support this public key type. See [SILC3] for
1102 other optional public key and certificate types allowed in SILC
1103 protocol. Public keys in SILC may be used to authenticate entities
1104 and to perform other tasks related to public key cryptography.
1106 The format of the SILC Public Key is as follows:
1117 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
1118 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1119 | Public Key Length |
1120 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1121 | Algorithm Name Length | |
1122 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1127 | Identifier Length | |
1128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1140 Figure 4: SILC Public Key
1144 o Public Key Length (4 bytes) - Indicates the full length
1145 of the public key, not including this field.
1147 o Algorithm Name Length (2 bytes) - Indicates the length
1148 of the Algorithm Length field, not including this field.
1150 o Algorithm name (variable length) - Indicates the name
1151 of the public key algorithm that the key is. See the
1152 section 3.10.2 Public Key Algorithms for defined names.
1154 o Identifier Length (2 bytes) - Indicates the length of
1155 the Identifier field, not including this field.
1157 o Identifier (variable length) - Indicates the identifier
1158 of the public key. This data can be used to identify
1159 the owner of the key. The identifier is of following
1163 HN Host name or IP address
1170 Examples of an identifier:
1172 `UN=priikone, HN=poseidon.pspt.fi, E=priikone@poseidon.pspt.fi'
1174 `UN=sam, HN=dummy.fi, RN=Sammy Sam, O=Company XYZ, C=Finland'
1176 At least user name (UN) and host name (HN) must be provided as
1177 identifier. The fields are separated by commas (`,'). If
1178 comma is in the identifier string it must be written as `\\,',
1179 for example, `O=Company XYZ\\, Inc.'.
1181 o Public Data (variable length) - Includes the actual
1182 public data of the public key.
1184 The format of this field for RSA algorithm is
1193 The format of this field for DSS algorithm is
1205 The variable length fields are multiple precession
1206 integers encoded as strings in both examples.
1208 Other algorithms must define their own type of this
1209 field if they are used.
1212 All fields in the public key are in MSB (most significant byte first)
1219 This section describes various SILC procedures such as how the
1220 connections are created and registered, how channels are created and
1221 so on. The section describes the procedures only generally as details
1222 are described in [SILC2] and [SILC3].
1226 4.1 Creating Client Connection
1228 This section descibres the procedure when client connects to SILC server.
1229 When client connects to server the server must perform IP address lookup
1230 and reverse IP address lookup to assure that the origin host really is
1231 who it claims to be. Client, host, connecting to server must have
1232 both valid IP address and fully qualified domain name (FQDN).
1234 After that client and server performs SILC Key Exchange protocol which
1235 will provide the key material used later in the communication. The
1236 key exchange protocol must be completed successfully before the connection
1237 registration may continue. The SILC Key Exchange protocol is described
1240 Typical server implementation would keep a list of connections that it
1241 allows to connect to the server. The implementation would check, for
1242 example, the connecting client's IP address from the connection list
1243 before the SILC Key Exchange protocol has been started. Reason for
1244 this is that if the host is not allowed to connect to the server there
1245 is no reason to perform a key exchange protocol.
1247 After successful key exchange protocol the client and server performs
1248 connection authentication protocol. The purpose of the protocol is to
1249 authenticate the client connecting to the server. Flexible
1250 implementation could also accept the client to connect to the server
1251 without explicit authentication. However, if authentication is
1252 desired for a specific client it may be based on passphrase or
1253 public key authentication. If authentication fails the connection
1254 must be terminated. The connection authentication protocol is described
1257 After successful key exchange and authentication protocol the client
1258 registers itself by sending SILC_PACKET_NEW_CLIENT packet to the
1259 server. This packet includes various information about the client
1260 that the server uses to create the client. Server creates the client
1261 and sends SILC_PACKET_NEW_ID to the client which includes the created
1262 Client ID that the client must start using after that. After that
1263 all SILC packets from the client must have the Client ID as the
1264 Source ID in the SILC Packet Header, described in [SILC2].
1266 Client must also get the server's Server ID that is to be used as
1267 Destination ID in the SILC Packet Header when communicating with
1268 the server (for example when sending commands to the server). The
1269 ID may be resolved in two ways. Client can take the ID from an
1270 previously received packet from server that must include the ID,
1271 or to send SILC_COMMAND_INFO command and receive the Server ID as
1274 Server may choose not to use the information received in the
1275 SILC_PACKET_NEW_CLIENT packet. For example, if public key or
1276 certificate were used in the authentication, server may use those
1277 informations rather than what it received from client. This is suitable
1278 way to get the true information about client if it is available.
1280 The nickname of client is initially set to the username sent in the
1281 SILC_PACKET_NEW_CLIENT packet. User should set the nickname to more
1282 suitable by sending SILC_COMMAND_NICK command. However, this is not
1283 required as part of registration process.
1285 Server must also distribute the information about newly registered
1286 client to its router (or if the server is router, to all routers in
1287 the SILC network). More information about this in [SILC2].
1291 4.2 Creating Server Connection
1293 This section descibres the procedure when server connects to its
1294 router (or when router connects to other router, the cases are
1295 equivalent). The procedure is very much alike when client connects
1296 to the server thus it is not repeated here.
1298 One difference is that server must perform connection authentication
1299 protocol with proper authentication. Proper authentication is based
1300 on passphrase or public key authentication.
1302 After server and router has successfully performed the key exchange
1303 and connection authentication protocol, the server register itself
1304 to the router by sending SILC_PACKET_NEW_SERVER packet. This packet
1305 includes the server's Server ID that it has created by itself and
1306 other relevant information about the server.
1308 After router has received the SILC_PACKET_NEW_SERVER packet it
1309 distributes the information about newly registered server to all routers
1310 in the SILC network. More information about this in [SILC2].
1312 As client needed to resolve the destination ID this must be done by the
1313 server that connected to the router, as well. The way to resolve it is
1314 to get the ID from previously received packet. Server must also start
1315 using its own Server ID as Source ID in SILC Packet Header and the
1316 router's Server ID as Destination when communicating with the router.
1318 If the server has already connected clients and locally created
1319 channels the server must distribute these informations to the router.
1320 The distribution is done by sending packet SILC_PACKET_NEW_CHANNEL.
1321 See [SILC2] for more information on this.
1325 4.3 Joining to a Channel
1327 This section describes the procedure when client joins to a channel.
1328 Client may join to channel by sending command SILC_COMMAND_JOIN to the
1329 server. If the receiver receiving join command is normal server the
1330 server must check its local list whether this channel already exists
1331 locally. This would indicate that some client connected to the server
1332 has already joined to the channel. If this is case the client is
1333 joined to the client, new channel key is created and information about
1334 newly joined channel is sent to the router. The new channel key is
1335 also distributed to the router and to all clients on the channel.
1337 If the channel does not exist in the local list the command must be
1338 sent to the router which will then perform the actual joining
1339 procedure. When server receives the reply to the command from the
1340 router it must be distributed to the client who sent the command
1341 originally. Server will also receive the channel key from the server
1342 that it must distribute to the client who originally requested the
1343 join command. The server must also save the channel key.
1345 If the receiver of the join command is router it must first check its
1346 local list whether anyone in the cell has already joined to the channel.
1347 If this is the case the client is joined to the channel and reply is
1348 sent to the client. If the command was sent by server the command reply
1349 is sent to the server who sent it. Then the router must also create
1350 new channel key and distribute it to all clients on the channel and
1351 all servers that has clients on the channel.
1353 If the channel does not exist on the router's local list it must
1354 check the global list whether the channel exists at all. If it does
1355 the client is joined to the channel as described previously. If
1356 the channel does not exist the channel is created and the client
1357 is joined to the channel. The channel key is also created and
1358 distributed as previously described. The client joining to the created
1359 channel is made automatically channel founder and both channel founder
1360 and channel operator privileges is set for the client.
1362 When the router joins the client to the channel it must send
1363 information about newly joined client to all routers in the SILC
1364 network. Also, if the channel was created in the process, information
1365 about newly created channel must also be distributed to all routers.
1366 The distribution of newly created channel is done by sending packet
1367 SILC_PACKET_NEW_CHANNEL.
1369 It is important to note that new channel key is created always when
1370 new client joins to channel, whether the channel has existed previously
1371 or not. This way the new client on the channel is not able to decrypt
1372 any of the old traffic on the channel.
1374 Client who receives the reply to the join command must start using
1375 the received Channel ID in the channel message communication thereafter.
1376 However, client must not start communicating on the channel before
1377 it has received the packet SILC_PACKET_CHANNEL_KEY.
1379 If client wants to know the other clients currently on the channel
1380 the client must send SILC_COMMAND_NAMES command to receive a list of
1381 channel users. Server implementation, however, may send command reply
1382 packet to SILC_COMMAND_NAMES command after client has joined to the
1383 channel even if the client has not sent the command.
1387 4.4 Channel Key Generation
1389 Channel keys are created by router who creates the channel by taking
1390 enough randomness from cryptographically strong random number generator.
1391 The key is generated always when channel is created, when new client
1392 joins a channel and after the key has expired. Key could expire for
1395 The key must also be re-generated whenever some client leaves a channel.
1396 In this case the key is created from scratch by taking enough randomness
1397 from the random number generator. After that the key is distributed to
1398 all clients on the channel. However, channel keys are cell specific thus
1399 the key is created only on the cell where the client, who leaved the
1400 channel, exists. While the server or router is creating the new channel
1401 key, no other client may join to the channel. Messages that are sent
1402 while creating the new key are still processed with the old key. After
1403 server has sent the SILC_PACKET_CHANNEL_KEY packet must client start
1404 using the new key. If server creates the new key the server must also
1405 send the new key to its router. See [SILC2] on more information about
1406 how channel messages must be encrypted and decrypted when router is
1411 4.5 Private Message Sending and Reception
1413 Private messages are sent point to point. Client explicitly destines
1414 a private message to specific client that is delivered to only to that
1415 client. No other client may receive the private message. The receiver
1416 of the private message is destined in the SILC Packet Header as any
1417 other packet as well.
1419 If the sender of a private message does not know the receiver's Client
1420 ID, it must resolve it from server. There are two ways to resolve the
1421 client ID from server; it is recommended that client ipmlementations
1422 send SILC_COMMAND_IDENTIFY command to receive the Client ID. Client
1423 may also send SILC_COMMAND_WHOIS command to receive the Client ID.
1424 If the sender has received earlier a private message from the receiver
1425 it should have cached the Client ID from the SILC Packet Header.
1427 Receiver of a private message should not explicitly trust the nickname
1428 that it receives in the Private Message Payload, described in [SILC2].
1429 Implementations could resolve the nickname from server, as described
1430 previously, and compare the received Client ID and the SILC Packet
1431 Header's Client ID. The nickname in the payload is merely provided
1432 to be displayed for end user.
1434 See [SILC2] for describtion of private message encryption and decryption
1439 4.6 Private Message Key Generation
1441 Private message may be protected by key generated by client. The key
1442 may be generated and sent to the other client by sending packet
1443 SILC_PACKET_PRIVATE_MESSAGE_KEY which travels through the network
1444 and is secured by session keys. After that the private message key
1445 is used in the private message communication between those clients.
1446 See more information about how this works technically in [SILC2].
1448 Other choice is to entirely use keys that are not sent through
1449 the SILC network at all. This significantly adds security. This key
1450 would be pre-shared-key that is known by both of the clients. Both
1451 agree about using the key and starts sending packets that indicate
1452 that the private message is secured using private message key. This
1453 is the technical aspect mentioned previously that is described
1456 If the private message keys are not set to be used, which is the
1457 case by default in SILC, the private messages are secured by using
1458 normal session keys established by SILC Key Exchange protocol.
1464 4.7 Channel Message Sending and Reception
1466 Channel messages are delivered to group of users. The group forms a
1467 channel and all clients on the channel receives messages sent to the
1470 Channel messages are destined to channel by specifying the Channel ID
1471 as Destination ID in the SILC Packet Header. The server must then
1472 distribute the message to all clients on the channel by sending the
1473 channel message destined explicitly to a client on the channel.
1475 See [SILC2] for describtion of channel message encryption and decryption
1480 4.8 Session Key Regeneration
1482 Session keys should be regenerated peridiocally, say, once in an hour.
1483 The re-key process is started by sending SILC_PACKET_REKEY packet to
1484 other end, to indicate that re-key must be performed.
1486 If perfect forward secrecy (PFS) flag was selected in the SILC Key
1487 Exchange protocol [SILC3] the re-key must cause new key exchange with
1488 SKE protocol. In this case the protocol is secured with the old key
1489 and the protocol results to new key material. See [SILC3] for more
1490 information. After the SILC_PACKET_REKEY packet is sent the sender
1491 will perform the SKE protocol.
1493 If PFS flag was not set, which is the default case, then re-key is done
1494 without executing SKE protocol. In this case, the new key is created by
1495 hashing the old key with hash function selected earlier in the SKE
1496 protocol. If the digest length of the hash function is too short for the
1497 key, then the key is distributed as described in section Processing the
1498 Key Material in [SILC3]. After both parties has regenerated the session
1499 key, both send SILC_PACKET_REKEY_DONE packet to each other. These packets
1500 are still secured with the old key. After these packets, following
1501 packets must be protected with the new key.
1505 4.9 Command Sending and Reception
1507 Client usually sends the commands in the SILC network. In this case
1508 the client simply sends the command packet to server and the server
1509 processes it and replies with command reply packet.
1511 However, if the server is not able to process the command, it is usually
1512 sent to the server's router. This is case for example with commands such
1513 as, SILC_COMMAND_JOIN and SILC_COMMAND_WHOIS commands. However, there
1514 are other commands as well. For example, if client sends the WHOIS
1515 command requesting specific information about some client the server must
1516 send the WHOIS command to router so that all clients in SILC network
1517 are searched. The router, on the other hand, sends the WHOIS command
1518 to further to receive the exact information about the requested client.
1519 The WHOIS command travels all the way to the server who owns the client
1520 and it replies with command reply packet. Finally, the server who
1521 sent the command receives the command reply and it must be able to
1522 determine which client sent the original command. The server then
1523 sends command reply to the client. Implementations should have some
1524 kind of cache to handle, for example, WHOIS information. Servers
1525 and routers along the route could all cache the information for faster
1526 referencing in the future.
1528 The commands sent by server may be sent hop by hop until someone is able
1529 to process the command. However, it is preferred to destine the command
1530 as precisely as it is possible. In this case, other routers en route
1531 must route the command packet by checking the true sender and true
1532 destination of the packet. However, servers and routers must not route
1533 command reply packets to clients coming from other server. Client
1534 must not accept command reply packet originated from anyone else but
1535 from its own server.
1542 5.1 SILC Commands Syntax
1544 This section briefly describes the syntax of the command notions
1545 in this document. Every field in command is separated from each
1546 other by whitespaces (` ') indicating that each field is independent
1547 argument and each argument must have own Command Argument Payload.
1548 The number of maximum arguments are defined with each command
1549 separately. The Command Argument Payload is described in [SILC2].
1551 Every command defines specific number for each argument. Currently,
1552 they are defined in ascending order; first argument has number one
1553 (1), second has number two (2) and so on. This number is set into the
1554 Argument Type field in the Command Argument Payload. This makes it
1555 possible to send the arguments in free order as the number must be
1556 used to identify the type of the argument. This makes is it also
1557 possible to have multiple optional arguments in commands and in
1558 command replies. The number of argument is marked in parentheses
1559 before the actual argument.
1566 Example: Arguments: (1) <nickname> (2) <username@host>
1570 Every command replies with Status Payload. This payload tells the
1571 sender of the command whether the command was completed succefully or
1572 whether there was an error. If error occured the payload includes the
1573 error type. In the next section the Status Payload is not described
1574 as it is common to all commands and has been described here. Commands
1575 may reply with other arguments as well. These arguments are command
1576 specific and are described in the next section.
1585 Arguments: (1) <nickname>[@<server>] (2) <message>
1588 The command has maximum of 3 arguments. However, only first
1589 and second arguments are mandatory.
1591 First argument <nickname> is mandatory but may have optional
1592 <nickname@server> format as well. Second argument is mandatory
1593 <message> argument. Third argument is optional <count> argument.
1595 The numbers in parentheses are the argument specific numbers
1596 that specify the type of the argument in Command Argument Payload.
1597 The receiver always knows that, say, argument number two (2) is
1598 <message> argument, regardles of the ordering of the arguments in
1599 the Command Payload.
1601 Reply messages to the command:
1604 Arguments: (1) <Status Payload> (2) [<channel list>]
1605 (3) <idle time> (4) [<away message>]
1607 This command may reply with maximum of 4 arguments. However,
1608 only the first and third arguments are mandatory. The numbers
1609 in the parentheses have the same meaning as in the upper
1610 command sending specification.
1612 Every command reply with <Status Payload>, it is mandatory
1613 argument for all command replies and for this reason it is not
1614 described in the command reply descriptions.
1621 SILC_STATUS_ERR_TOO_MANY_TARGETS
1622 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1623 SILC_STATUS_ERR_NO_SUCH_NICK
1625 Every command reply also defines set of status message that it
1626 may return inside the <Status Payload>. All status messages
1627 are defined in the section 5.3 SILC Command Status Types.
1632 5.2 SILC Commands List
1634 This section lists all SILC commands, however, it is expected that a
1635 implementation and especially client implementation has many more
1636 commands that has only local affect. These commands are official
1637 SILC commands that has both client and server sides and cannot be
1638 characterized as local commands.
1640 List of all defined commands in SILC follows.
1645 None. This is reserved command and must not be sent.
1648 2 SILC_COMMAND_WHOIS
1651 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1653 Whois. Whois command is used to query various information about
1654 specific user. The user maybe requested by their nickname and
1655 server name. The query may find multiple matching users as
1656 there are no unique nicknames in the SILC. The <count> option
1657 maybe given to narrow down the number of accepted results. If
1658 this is not defined there are no limit of accepted results.
1659 The query may also be narrowed down by defining the server name
1662 To prevent miss-use of this service wildcards in the nickname
1663 or in the servername are not permitted. It is not allowed
1664 to request all users on some server. The WHOIS requests must
1665 be based on specific nickname request.
1667 The WHOIS request must be always forwarded to router by server
1668 so that all users are searched. However, the server still must
1669 search its locally connected clients. The server must send
1670 this command to the server who owns the requested client. That
1671 server must reply to the command.
1673 Reply messages to the command:
1676 Arguments: (1) <Status Payload> (2) <Client ID>
1677 (3) <nickname>[@<server>] (4) <username@host>
1678 (5) <real name> (6) [<channel list>]
1681 This command may reply with several command reply messages to
1682 form a list of results. In this case the status payload will
1683 include STATUS_LIST_START status in the first reply and
1684 STATUS_LIST_END in the last reply to indicate the end of the
1685 list. If there are only one reply the status is set to normal
1688 The command replies include the Client ID of the nickname,
1689 nickname and servername, username and hostnamea and users real
1690 name. Client should process these replies only after the last
1691 reply has been received with the STATUS_LIST_END status. If the
1692 <count> option were defined in the query there will be only
1693 <count> many replies from the server.
1698 SILC_STATUS_LIST_START
1699 SILC_STATUS_LIST_END
1700 SILC_STATUS_ERR_NO_SUCH_NICK
1701 SILC_STATUS_ERR_WILDCARDS
1702 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1703 SILC_STATUS_ERR_TOO_MANY_PARAMS
1706 3 SILC_COMMAND_WHOWAS
1709 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1711 Whowas. This command is used to query history information about
1712 specific user. The user maybe requested by their nickname and
1713 server name. The query may find multiple matching users as there
1714 are no unique nicknames in the SILC. The <count> option maybe
1715 given to narrow down the number of accepted results. If this
1716 is not defined there are no limit of accepted results. The query
1717 may also be narrowed down by defining the server name of the
1720 To prevent miss-use of this service wildcards in the nickname
1721 or in the servername are not permitted. The WHOWAS requests must
1722 be based on specific nickname request.
1724 The WHOWAS request must be always forwarded to router by server
1725 so that all users are searched. However, the server still must
1726 search its locally connected clients.
1728 Reply messages to the command:
1731 Arguments: (1) <Status Payload> (2) <nickname>[@<server>]
1734 This command may reply with several command reply messages to form
1735 a list of results. In this case the status payload will include
1736 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1737 the last reply to indicate the end of the list. If there are only
1738 one reply the status is set to normal STATUS_OK.
1740 The command replies with nickname and username and hostname.
1741 Every server must keep history for some period of time of its
1742 locally connected clients.
1747 SILC_STATUS_LIST_START
1748 SILC_STATUS_LIST_END
1749 SILC_STATUS_ERR_NO_SUCH_NICK
1750 SILC_STATUS_ERR_WILDCARDS
1751 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1752 SILC_STATUS_ERR_TOO_MANY_PARAMS
1755 4 SILC_COMMAND_IDENTIFY
1758 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1760 Identify. Identify command is almost analogous to WHOIS command,
1761 except that it does not return as much information. Only relevant
1762 information such as Client ID is returned. This is usually used
1763 to get the Client ID of a client used in the communication with
1766 The query may find multiple matching users as there are no unique
1767 nicknames in the SILC. The <count> option maybe given to narrow
1768 down the number of accepted results. If this is not defined there
1769 are no limit of accepted results. The query may also be narrowed
1770 down by defining the server name of the nickname.
1772 To prevent miss-use of this service wildcards in the nickname
1773 or in the servername are not permitted. It is not allowed
1774 to request all users on some server. The IDENTIFY requests must
1775 be based on specific nickname request.
1777 Implementations may not want to give interface access to this
1778 commands as it is hardly a command that would be used a end user.
1779 However, it must be implemented as it is used with private message
1782 The IDENTIFY must be always forwarded to router by server so that
1783 all users are searched. However, server must still search its
1784 locally connected clients.
1786 Reply messages to the command:
1789 Arguments: (1) <Status Payload> (2) <Client ID>
1790 (3) [<nickname>[@<server>]] (4) [<username@host>]
1792 This command may reply with several command reply messages to form
1793 a list of results. In this case the status payload will include
1794 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1795 the last reply to indicate the end of the list. If there are only
1796 one reply the status is set to normal STATUS_OK.
1798 The command replies with Client ID of the nickname and if more
1799 information is available it may reply with nickname and username
1800 and hostname. If the <count> option were defined in the query
1801 there will be only <count> many replies from the server.
1806 SILC_STATUS_LIST_START
1807 SILC_STATUS_LIST_END
1808 SILC_STATUS_ERR_NO_SUCH_NICK
1809 SILC_STATUS_ERR_WILDCARDS
1810 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1811 SILC_STATUS_ERR_TOO_MANY_PARAMS
1817 Arguments: (1) <nickname>
1819 Set/change nickname. This command is used to set nickname for
1820 user. There is no limit of the length of the nickname in SILC.
1821 Nickname must not include any spaces (` '), non-printable
1822 characters, commas (`,') and any wildcard characters. Note:
1823 nicknames in SILC are case-sensitive which must be taken into
1824 account when searching clients by nickname.
1826 Reply messages to the command:
1829 Arguments: (1) <Status Payload> (2) <New ID Payload>
1831 This command is replied always with New ID Payload that is
1832 generated by the server every time user changes their nickname.
1833 Client receiving this payload must start using the received
1834 Client ID as its current valid Client ID. The New ID Payload
1835 is described in [SILC2].
1840 SILC_STATUS_ERR_WILDCARDS
1841 SILC_STATUS_ERR_NICKNAME_IN_USE
1842 SILC_STATUS_ERR_BAD_NICKNAME
1843 SILC_STATUS_ERR_NOT_REGISTERED
1844 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1845 SILC_STATUS_ERR_TOO_MANY_PARAMS
1851 Arguments: (1) [<Channel ID>] [<server>]
1853 The list command is used to list channels and their topics on
1854 current server. If the <Channel ID> parameter is used, only the
1855 status of that channel is displayed. Secret channels are not
1856 listed at all. Private channels are listed with status indicating
1857 that the channel is private.
1859 If the <server> argument is specified the specified server's
1860 channels are listed. In this case the command must be sent to
1861 the server who owns the channel that was requested.
1863 Reply messages to the command:
1866 Arguments: (1) <Status Payload> (2) <channel>
1869 This command may reply with several command reply messages to form
1870 a list of results. In this case the status payload will include
1871 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1872 the last reply to indicate the end of the list. If there are only
1873 one reply the status is set to normal STATUS_OK.
1875 This command replies with channel name and the topic of the
1876 channel. If the channel is private channel the <topic> includes
1882 SILC_STATUS_LIST_START
1883 SILC_STATUS_LIST_END
1884 SILC_STATUS_ERR_WILDCARDS
1885 SILC_STATUS_ERR_NOT_REGISTERED
1886 SILC_STATUS_ERR_TOO_MANY_PARAMS
1887 SILC_STATUS_ERR_NO_SUCH_CHANNEL
1888 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
1889 SILC_STATUS_ERR_NO_SUCH_SERVER
1892 7 SILC_COMMAND_TOPIC
1895 Arguments: (1) <Channel ID> (2) [<server>]]
1897 This command is used to change or view the topic of a channel.
1898 The topic for channel <Channel ID> is returned if there is no
1899 <topic> given. If the <topic> parameter is present, the topic
1900 for that channel will be changed, if the channel modes permit
1903 Reply messages to the command:
1906 Arguments: (1) <Status Payload> (2) [<topic>]
1908 The command may reply with the topic of the channel if it is
1914 SILC_STATUS_ERR_NOT_ON_CHANNEL
1915 SILC_STATUS_ERR_WILDCARDS
1916 SILC_STATUS_ERR_NOT_REGISTERED
1917 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1918 SILC_STATUS_ERR_NO_SUCH_CHANNEL
1919 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
1920 SILC_STATUS_ERR_NO_CHANNEL_ID
1921 SILC_STATUS_ERR_BAD_CHANNEL_ID
1922 SILC_STATUS_ERR_TOO_MANY_PARAMS
1923 SILC_STATUS_ERR_NO_CHANNEL_PRIV
1926 8 SILC_COMMAND_INVITE
1929 Arguments: (1) <Client ID> (2) <channel>
1931 This command is used to invite other clients to join to the
1932 channel. There is no requirement that the channel the target
1933 client is being invited to must exist or be a valid channel.
1934 The <Client ID> argument is the target client's ID that is being
1937 Reply messages to the command:
1941 Arguments: (1) <Status Payload>
1943 This command replies only with Status Payload.
1948 SILC_STATUS_ERR_NOT_ON_CHANNEL
1949 SILC_STATUS_ERR_WILDCARDS
1950 SILC_STATUS_ERR_NOT_REGISTERED
1951 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1952 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
1953 SILC_STATUS_ERR_TOO_MANY_PARAMS
1954 SILC_STATUS_ERR_NO_RECIPIENT
1955 SILC_STATUS_ERR_USER_ON_CHANNEL
1956 SILC_STATUS_ERR_NO_CLIENT_ID
1962 Arguments: (1) [<quit message>]
1964 This command is used by client to end SILC session. The server
1965 must close the connection to a client which sends this command.
1966 if <quit message> is given it will be sent to other clients on
1967 channel if the client is on channel when quitting.
1969 Reply messages to the command:
1971 This command does not reply anything.
1974 10 SILC_COMMAND_KILL
1977 Arguments: (1) <Client ID> (2) [<comment>]
1979 This command is used by SILC operators to remove a client from
1980 SILC network. The removing has temporary effects and client may
1981 reconnect to SILC network. The <Client ID> is the client to be
1982 removed from SILC. The <comment> argument may be provided to
1983 give to the removed client some information why it was removed
1986 Reply messages to the command:
1989 Arguments: (1) <Status Payload>
1991 This command replies only with Status Payload.
1996 SILC_STATUS_ERR_WILDCARDS
1997 SILC_STATUS_ERR_NOT_REGISTERED
1998 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1999 SILC_STATUS_ERR_TOO_MANY_PARAMS
2000 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2001 SILC_STATUS_ERR_NO_CLIENT_ID
2007 11 SILC_COMMAND_INFO
2010 Arguments: (1) [<server>]
2012 This command is used to fetch various information about a server.
2013 If <server> argument is specified the command must be sent to
2014 the requested server.
2016 Reply messages to the command:
2019 Arguments: (1) <Status Payload> (2) <Server ID>
2022 This command replies with the Server ID of the server and a
2023 string which tells the information about the server.
2028 SILC_STATUS_ERR_WILDCARDS
2029 SILC_STATUS_ERR_NOT_REGISTERED
2030 SILC_STATUS_ERR_TOO_MANY_PARAMS
2031 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2032 SILC_STATUS_ERR_NO_SUCH_SERVER
2035 12 SILC_COMMAND_CONNECT
2038 Arguments: (1) <Server ID>
2039 (2) [<remote server/router>[:<port>]]
2041 This command is used by operators to force a server to try to
2042 establish a new connection to another router (if the connecting
2043 server is normal server) or server (if the conneceting server is
2044 router server). Operator may specify the server/router to be
2045 connected by setting <remote server> argument.
2047 Reply messages to the command:
2050 Arguments: (1) <Status Payload>
2052 This command replies only with Status Payload.
2059 SILC_STATUS_ERR_WILDCARDS
2060 SILC_STATUS_ERR_NOT_REGISTERED
2061 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2062 SILC_STATUS_ERR_TOO_MANY_PARAMS
2063 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2064 SILC_STATUS_ERR_NO_SERVER_PRIV
2065 SILC_STATUS_ERR_NO_ROUTER_PRIV
2068 13 SILC_COMMAND_PING
2071 Arguments: (1) <Server ID>
2073 This command is used by clients to test the communication
2074 channel to its server if client suspects that the communication
2075 is not working correctly. The <Server ID> is the ID of the
2076 server the client is connected to.
2078 Reply messages to the command:
2081 Arguments: (1) <Status Payload>
2083 This command replies only with Status Payload. Server returns
2084 SILC_STATUS_OK in Status Payload if pinging was successful.
2089 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2090 SILC_STATUS_ERR_TOO_MANY_PARAMS
2091 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2092 SILC_STATUS_ERR_NOT_REGISTERED
2095 14 SILC_COMMAND_OPER
2098 Arguments: (1) <username> (2) <authentication data>
2100 This command is used by normal client to obtain server operator
2101 privileges on some server or router. Note that router operator
2102 has router privileges that supersedes the server operator
2103 privileges and this does not obtain those privileges. Client
2104 must use SILCOPER command to obtain router level privileges.
2106 The <username> is the username set in the server configurations
2107 as operator. The <authentication data> is the data that the
2108 client is authenticated against. It may be passphrase prompted
2109 for user on client's screen or it may be public key
2110 authentication data (data signed with private key), or
2113 Reply messages to the command:
2116 Arguments: (1) <Status Payload>
2118 This command replies only with Status Payload.
2123 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2124 SILC_STATUS_ERR_TOO_MANY_PARAMS
2125 SILC_STATUS_ERR_NOT_REGISTERED
2126 SILC_STATUS_ERR_BAD_PASSWORD
2127 SILC_STATUS_ERR_AUTH_FAILED
2130 15 SILC_COMMAND_JOIN
2133 Arguments: (1) <channel> (2) [<passphrase>]
2136 Join to channel/create new channel. This command is used to
2137 join to a channel. If the channel does not exist the channel is
2138 created on the server receiving the join request. The channel
2139 may be protected with passphrase. If this is the case the
2140 passphrase must be sent along the join command.
2142 The name of the <channel> must not include any spaces (` '),
2143 non-printable characters, commas (`,') or any wildcard characters.
2145 Cipher to be used to secure the traffic on the channel may be
2146 requested by sending the name of the requested <cipher>. This
2147 is used only if the channel does not exist and is created. If
2148 the channel already exists the cipher set previously for the
2149 channel will be used to secure the traffic.
2151 The server must check whether the user is allowed to join to
2152 the requested channel. Various modes set to the channel affect
2153 the ability of the user to join the channel. These conditions
2156 o The user must be invited to the channel if the channel
2157 is invite-only channel.
2159 o The Client ID/nickname/username/hostname must not match
2162 o The correct passphrase must be provided if passphrase
2163 is set to the channel.
2165 o The user count limit, if set, must not be reached.
2167 Reply messages to the command:
2170 Arguments: (1) <Status Payload> (2) <channel>
2171 (3) <Channel ID> (4) <channel mode mask>
2174 This command replies with the channel name requested by the
2175 client, channel ID of the channel and topic of the channel
2176 if it exists. It also replies with the channel mode mask
2177 which tells all the modes set on the channel. If the
2178 channel is created the mode mask is zero (0).
2180 Client must not start transmitting to the channel even after
2181 server has replied to this command. Client is permitted to
2182 start transmitting on channel after server has sent packet
2183 SILC_PACKET_CHANNEL_KEY to the client.
2188 SILC_STATUS_ERR_WILDCARDS
2189 SILC_STATUS_ERR_NOT_REGISTERED
2190 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2191 SILC_STATUS_ERR_TOO_MANY_PARAMS
2192 SILC_STATUS_ERR_BAD_PASSWORD
2193 SILC_STATUS_ERR_CHANNEL_IS_FULL
2194 SILC_STATUS_ERR_NOT_INVITED
2195 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
2196 SILC_STATUS_ERR_BAD_CHANNEL
2197 SILC_STATUS_ERR_USER_ON_CHANNEL
2200 16 SILC_COMMAND_MOTD
2203 Arguments: (1) <server>
2205 This command is used to query the Message of the Day of a server.
2207 Reply messages to the command:
2210 Arguments: (1) <Status Payload> (2) [<motd>]
2212 This command replies with the motd message if it exists.
2217 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2218 SILC_STATUS_ERR_TOO_MANY_PARAMS
2219 SILC_STATUS_ERR_NOT_REGISTERED
2220 SILC_STATUS_ERR_NO_SUCH_SERVER
2223 17 SILC_COMMAND_UMODE
2226 Arguments: (1) <Client ID> (2) <client mode mask>
2228 This command is used by client to set/unset modes for itself.
2229 However, there are some modes that the client may not set itself,
2230 but they will be set by server. However, client may unset any
2231 mode. Modes may be masked together ORing them thus having
2232 several modes set. Client must keep its client mode mask
2233 locally so that the mode setting/unsetting would work without
2234 problems. Client may change only its own modes.
2236 Following client modes are defined:
2238 0x0000 SILC_UMODE_NONE
2240 No specific mode for client. This is the initial
2241 setting when new client is created. The client is
2245 0x0001 SILC_UMODE_SERVER_OPERATOR
2247 Marks the user as server operator. Client cannot
2248 set this mode itself. Server sets this mode to the
2249 client when client attains the server operator
2250 privileges by SILC_COMMAND_OPER command. Client
2251 may unset the mode itself.
2254 0x0002 SILC_UMODE_ROUTER_OPERATOR
2256 Marks the user as router (SILC) operator. Client
2257 cannot this mode itself. Router sets this mode to
2258 the client when client attains the router operator
2259 privileges by SILC_COMMAND_SILCOPER command. Client
2260 may unset the mode itself.
2262 Reply messages to the command:
2265 Arguments: (1) <Status Payload> (2) <client mode mask>
2267 This command replies with the changed client mode mask that
2268 the client is required to keep locally.
2274 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2275 SILC_STATUS_ERR_TOO_MANY_PARAMS
2276 SILC_STATUS_ERR_NOT_REGISTERED
2277 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2278 SILC_STATUS_ERR_BAD_CLIENT_ID
2279 SILC_STATUS_ERR_NOT_YOU
2280 SILC_STATUS_ERR_UNKNOWN_MODE
2281 SILC_STATUS_ERR_NO_RECIPIENT
2282 SILC_STATUS_ERR_NO_CLIENT_ID
2285 18 SILC_COMMAND_CMODE
2288 Arguments: (1) <Channel ID> (2) <channel mode mask>
2289 (3) [<user limit>] (4) [<passphrase>]
2290 (5) [<Client ID>] (6) [<cipher>[:<key len>]]
2292 This command is used by client to set or change channel flags on
2293 a channel. Channel has several modes that set various properties
2294 of a channel. Modes may be masked together by ORing them thus
2295 having several modes set. The <Channel ID> is the ID of the
2296 target channel. The client changing channel mode must be on
2297 the same channel and poses sufficient privileges to be able to
2300 Following channel modes are defined:
2302 0x0000 SILC_CMODE_NONE
2304 No specific mode on channel. This is the default when
2305 channel is created. This means that channel is just plain
2309 0x0001 SILC_CMODE_PRIVATE
2311 Channel is private channel. Private channels are shown
2312 in the channel list listed with SILC_COMMAND_LIST command
2313 with indicatioin that the channel is private. Also,
2314 client on private channel will no be detected to be on
2315 the channel as the channel is not shown in the client's
2316 currently joined channel list. Channel founder and
2317 channel operator may set/unset this mode.
2319 Typical implementation would use [+|-]p on user interface
2320 to set/unset this mode.
2323 0x0002 SILC_CMODE_SECRET
2325 Channel is secret channel. Secret channels are not shown
2326 in the list listed with SILC_COMMAND_LIST command. Secret
2327 channels can be considered to be invisible channels.
2328 Channel founder and channel operator may set/unset this
2331 Typical implementation would use [+|-]s on user interface
2332 to set/unset this mode.
2335 0x0004 SILC_CMODE_PRIVKEY
2337 Channel uses private channel key to protect the traffic
2338 on the channel. When this mode is set the client will be
2339 responsible to set the key it wants to use to encrypt and
2340 decrypt the traffic on channel. Server generated channel
2341 keys are not used at all. This mode provides additional
2342 security as clients on channel may agree to use private
2343 channel key that even servers do not know. Naturally,
2344 this requires that every client on the channel knows
2345 the key before hand (it is considered to be pre-shared-
2346 key). This specification does not define how the private
2347 channel key is set as it is entirely local setting on
2350 As it is local setting it is possible to have several
2351 private channel keys on one channel. In this case several
2352 clients can talk on same channel but only those clients
2353 that share the key with the message sender will be able
2354 to hear the talking. Client should not display those
2355 message for the end user that it is not able to decrypt
2356 when this mode is set.
2358 Only channel founder may set/unset this mode. If this
2359 mode is unset the server will distribute new channel
2360 key to all clients on the channel which will be used
2363 Typical implementation would use [+|-]k on user interface
2364 to set/unset this mode.
2367 0x0008 SILC_CMODE_INVITE
2369 Channel is invite only channel. Client may join to this
2370 channel only if it is invited to the channel. Channel
2371 founder and channel operator may set/unset this mode.
2373 Typical implementation would use [+|-]i on user interface
2374 to set/unset this mode.
2377 0x0010 SILC_CMODE_TOPIC
2379 The topic of the channel may only be set by client that
2380 is channel founder or channel operator. Normal clients
2381 on channel will not be able to set topic when this mode
2382 is set. Channel founder and channel operator may set/
2385 Typical implementation would use [+|-]t on user interface
2386 to set/unset this mode.
2389 0x0020 SILC_CMODE_ULIMIT
2391 User limit has been set to the channel. New clients
2392 may not join to the channel when the limit set is
2393 reached. Channel founder and channel operator may set/
2394 unset the limit. The <user limit> argument is the
2395 number of limited users.
2397 Typical implementation would use [+|-]l on user interface
2398 to set/unset this mode.
2401 0x0040 SILC_CMODE_PASSPHRASE
2403 Passphrase has been set to the channel. Client may
2404 join to the channel only if it is able to provide the
2405 correct passphrase. Setting passphrases to channel
2406 is entirely safe as all commands are protected in the
2407 SILC network. Only channel founder may set/unset
2408 the passphrase. The <passphrase> argument is the
2411 Typical implementation would use [+|-]a on user interface
2412 to set/unset this mode.
2415 0x0080 SILC_CMODE_BAN
2417 Ban mask has been set to the channel. The ban mask
2418 may be used to ban specific clients to join the channel.
2419 The <ban mask> argument is the set ban mask. When
2420 unsetting a ban mask the mask must be provided as
2421 argument. Channel founder and channel operator may
2422 set/unset this mode. Channel founder may not be
2423 added to the ban list.
2425 Typical implementation would use [+|-]b on user interface
2426 to set/unset this mode.
2429 0x0100 SILC_CMODE_OPERATOR
2431 Sets channel operator privileges on the channel for a
2432 client on the channel. The <Client ID> argument is the
2433 target client on the channel. Channel founder and
2434 channel operator may set/unset (promote/demote) this
2437 Typical implementation would use [+|-]o on user interface
2438 to set/unset this mode.
2441 0x0200 SILC_CMODE_CIPHER
2443 Sets specific cipher to be used to protect channel
2444 traffic. The <cipher> argument is the requested cipher.
2445 When set or unset the server must re-generate new
2446 channel key. If <key len> argument is specified with
2447 <cipher> argument the new key is generated of <key len>
2450 Typical implementation would use [+|-]c on user interface
2451 to set/unset this mode.
2454 To make the mode system work, client must keep the channel mode
2455 mask locally so that the mode setting and unsetting would work
2456 without problems. The client receives the initial channel mode
2457 mask when it joins to the channel. When the mode changes on
2458 channel the server distributes the changed channel mode mask to
2459 all clients on the channel by sending SILC_COMMAND_CMODE command
2463 Reply messages to the command:
2466 Arguments: (1) <Status Payload> (2) <channel mode mask>
2468 This command replies with the changed channel mode mask that
2469 client is required to keep locally. The same mask is also
2470 sent to all clients on channel by sending additional command
2476 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2477 SILC_STATUS_ERR_TOO_MANY_PARAMS
2478 SILC_STATUS_ERR_NOT_REGISTERED
2479 SILC_STATUS_ERR_NOT_ON_CHANNEL
2480 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2481 SILC_STATUS_ERR_BAD_CHANNEL_ID
2482 SILC_STATUS_ERR_NO_CHANNEL_ID
2483 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2484 SILC_STATUS_ERR_UNKNOWN_MODE
2485 SILC_STATUS_ERR_NO_CLIENT_ID
2490 19 SILC_COMMAND_KICK
2493 Arguments: (1) <channel> (2) <Client ID>
2496 This command is used by channel operators to remove a client from
2497 channel. The <channel> argument is the channel the client to be
2498 removed is on currently. Note that the "kicker" must be on the same
2499 channel. If <comment> is provided it will be sent to the removed
2502 Reply messages to the command:
2505 Arguments: (1) <Status Payload>
2507 This command replies only with Status Payload.
2512 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2513 SILC_STATUS_ERR_TOO_MANY_PARAMS
2514 SILC_STATUS_ERR_NOT_REGISTERED
2515 SILC_STATUS_ERR_NO_SUCH_CHANNEL
2516 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2517 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2518 SILC_STATUS_ERR_NO_CLIENT_ID
2521 20 SILC_COMMAND_RESTART
2526 This command may only be used by server operator to force a
2527 server to restart itself.
2529 Reply messages to the command:
2532 Arguments: (1) <Status Payload>
2534 This command replies only with Status Payload.
2541 SILC_STATUS_ERR_NOT_REGISTERED
2542 SILC_STATUS_ERR_NO_SERVER_PRIV
2545 21 SILC_COMMAND_CLOSE
2548 Arguments: (1) <Server ID>
2550 This command is used only by operator to close connection to a
2551 remote site. The <Server ID> argument is the ID of the remote
2552 site and must be valid.
2554 Reply messages to the command:
2557 Arguments: (1) <Status Payload>
2559 This command replies only with Status Payload.
2566 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2567 SILC_STATUS_ERR_TOO_MANY_PARAMS
2568 SILC_STATUS_ERR_NOT_REGISTERED
2569 SILC_STATUS_ERR_NO_SUCH_SERVER
2570 SILC_STATUS_ERR_NO_SERVER_PRIV
2571 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2579 This command is used only by operator to shutdown the server.
2580 All connections to the server will be closed and the server is
2583 Reply messages to the command:
2588 Arguments: (1) <Status Payload>
2590 This command replies only with Status Payload.
2595 SILC_STATUS_ERR_NOT_REGISTERED
2596 SILC_STATUS_ERR_NO_SERVER_PRIV
2599 23 SILC_COMMAND_SILCOPER
2602 Arguments: (1) <username> (2) <authentication data>
2604 This command is used by normal client to obtain router operator
2605 privileges (also known as SILC operator) on some router. Note
2606 that router operator has router privileges that supersedes the
2607 server operator privileges.
2609 The <username> is the username set in the server configurations
2610 as operator. The <authentication data> is the data that the
2611 client is authenticated against. It may be passphrase prompted
2612 for user on client's screen or it may be public key
2613 authentication data (data signed with private key), or
2616 Difference between router operator and server operator is that
2617 router operator is able to handle cell level properties while
2618 server operator (even on router server) is able to handle only
2619 local properties, such as, local connections and normal server
2622 Reply messages to the command:
2625 Arguments: (1) <Status Payload>
2627 This command replies only with Status Payload.
2632 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2633 SILC_STATUS_ERR_TOO_MANY_PARAMS
2634 SILC_STATUS_ERR_NOT_REGISTERED
2635 SILC_STATUS_ERR_BAD_PASSWORD
2636 SILC_STATUS_ERR_AUTH_FAILED
2639 24 SILC_COMMAND_LEAVE
2642 Arguments: (1) <Channel ID>
2644 This command is used by client to leave a channel the client is
2645 joined to. After a client has leaved the channel the server
2646 must create new key for the channel and distribute to all clients
2647 still currently on the channel.
2649 Reply messages to the command:
2652 Arguments: (1) <Status Payload>
2654 This command replies only with Status Payload.
2659 SILC_STATUS_ERR_NOT_REGISTERED
2660 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2661 SILC_STATUS_ERR_TOO_MANY_PARAMS
2662 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2663 SILC_STATUS_ERR_BAD_CHANNEL_ID
2664 SILC_STATUS_ERR_NO_CHANNEL_ID
2667 25 SILC_COMMAND_NAMES
2670 Arguments: (1) <Channel ID>
2672 This command is used to list user names currently on the requested
2673 channel; argument <Channel ID>. The server must resolve the
2674 user names and send a comma (`,') separated list of user names
2675 on the channel. Server or router may resolve the names by sending
2676 SILC_COMMAND_WHOIS commands.
2678 If the requested channel is a private or secret channel, this
2679 command must not send the list of users, as private and secret
2680 channels cannot be seen by outside. In this case the returned
2681 name list may include a indication that the server could not
2682 resolve the names of the users on the channel.
2684 Reply messages to the command:
2687 Arguments: (1) <Status Payload> (2) <name list>
2689 This command replies with the comma separated list of users on
2695 SILC_STATUS_ERR_NOT_REGISTERED
2696 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2697 SILC_STATUS_ERR_TOO_MANY_PARAMS
2698 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2699 SILC_STATUS_ERR_BAD_CHANNEL_ID
2700 SILC_STATUS_ERR_NO_CHANNEL_ID
2701 SILC_STATUS_ERR_NOT_ON_CHANNEL
2706 Currently undefined commands.
2709 255 SILC_COMMAND_MAX
2711 Reserved command. This must not be sent.
2716 5.3 SILC Command Status Types
2719 5.3.1 SILC Command Status Payload
2721 Command Status Payload is sent in command reply messages to indicate
2722 the status of the command. The payload is one of argument in the
2723 command thus this is the data area in Command Argument Payload described
2724 in [SILC2]. The payload is only 2 bytes of length. Following diagram
2725 represents the Command Status Payload (field is always in MSB order).
2731 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
2732 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2734 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2738 Figure 5: SILC Command Status Payload
2742 o Status Message (2 bytes) - Indicates the status message.
2743 All Status messages are described in the next section.
2748 5.3.2 SILC Command Status List
2750 Command Status messages are returned in the command reply messages
2751 to indicate whether the command were executed without errors. If error
2752 has occured the status tells which error occured. Status payload only
2753 sends numeric reply about the status. Receiver of the payload must
2754 convert the numeric values into human readable error messages. The
2755 list of status messages below has an example human readable error
2756 messages that client may display for the user.
2758 List of all defined command status messages following.
2761 Generic status messages:
2765 Ok status. Everything went Ok. The status payload maybe
2766 safely ignored in this case.
2768 1 SILC_STATUS_LIST_START
2770 Start of the list. There will be several command replies and
2771 this reply is the start of the list.
2773 2 SILC_STATUS_LIST_END
2775 End of the list. There were several command replies and this
2776 reply is the last of the list. There won't be other replies
2777 beloning to this list after this one.
2781 Currently undefined and has been reserved for the future.
2784 Error status message:
2786 10 SILC_STATUS_ERR_NO_SUCH_NICK
2788 "No such nickname". Requested nickname does not exist.
2790 11 SILC_STATUS_ERR_NO_SUCH_CHANNEL
2792 "No such channel". Requested channel name does not exist.
2794 12 SILC_STATUS_ERR_NO_SUCH_SERVER
2796 "No such server". Requested server name does not exist.
2798 13 SILC_STATUS_ERR_TOO_MANY_TARGETS
2800 "Duplicate recipients. No message delivered". Message were
2801 tried to be sent to recipient which has several occurrences in
2804 14 SILC_STATUS_ERR_NO_RECIPIENT
2806 "No recipient given". Command required recipient which was
2809 15 SILC_STATUS_ERR_UNKNOWN_COMMAND
2811 "Unknown command". Command sent to server is unknown by the
2814 16 SILC_STATUS_ERR_WILDCARDS
2816 "Wildcards cannot be used". Wildcards were provided but they
2819 17 SILC_STATUS_ERR_NO_CLIENT_ID
2821 "No Client ID given". Client ID were expected as command
2822 parameter but were not found.
2824 18 SILC_STATUS_ERR_NO_CHANNEL_ID
2826 "No Channel ID given". Channel ID were expected as command
2827 parameter but were not found.
2829 19 SILC_STATUS_ERR_BAD_CLIENT_ID
2831 "Bad Client ID". Client ID provided were erroneous.
2833 20 SILC_STATUS_ERR_BAD_CHANNEL_ID
2835 "Bad Channel ID". Channel ID provided were erroneous.
2837 21 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2839 "No such Client ID". Client ID provided does not exist.
2842 22 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2844 "No such Channel ID". Channel ID provided does not exist.
2846 23 SILC_STATUS_ERR_NICKNAME_IN_USE
2848 "Nickname already exists". Nickname created could not be
2849 registered because number of same nicknames were already set to
2850 maximum. This is not expected to happen in real life but is
2853 24 SILC_STATUS_ERR_NOT_ON_CHANNEL
2855 "You are not on that channel". The command were specified for
2856 client user is not currently on.
2858 25 SILC_STATUS_ERR_USER_ON_CHANNEL
2860 "User already on channel". User were invited on channel they
2863 26 SILC_STATUS_ERR_NOT_REGISTERED
2865 "You have not registered". User executed command that requires
2866 the client to be registered on the server before it may be
2869 27 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2871 "Not enough parameters". Command requires more parameters
2874 28 SILC_STATUS_ERR_TOO_MANY_PARAMS
2876 "Too many parameters". Too many parameters were provided
2879 29 SILC_STATUS_ERR_PERM_DENIED
2881 "Your host is not among the privileged". The client tried to
2882 register on server that does not allow this host to connect.
2884 30 SILC_STATUS_ERR_BANNED_FROM_SERVER
2886 "You are banned from this server". The client tried to register
2887 on server that has explicitly denied this host to connect.
2891 31 SILC_STATUS_ERR_BAD_PASSWORD
2893 "Cannot join channel. Incorrect password". Password provided for
2894 channel were not accepted.
2896 32 SILC_STATUS_ERR_CHANNEL_IS_FULL
2898 "Cannot join channel. Channel is full". The channel is full
2899 and client cannot be joined to it.
2901 33 SILC_STATUS_ERR_NOT_INVITED
2903 "Cannot join channel. You have not been invited". The channel
2904 is invite only channel and client has not been invited.
2906 34 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
2908 "Cannot join channel. You have been banned". The client has
2909 been banned from the channel.
2911 35 SILC_STATUS_ERR_UNKNOWN_MODE
2913 "Unknown mode". Mode provided by the client were unknown to
2916 36 SILC_STATUS_ERR_NOT_YOU
2918 "Cannot change mode for other users". User tried to change
2919 someone else's mode.
2921 37 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2923 "Permission denied. You are not channel operator". Command may
2924 be executed only by channel operator.
2926 38 SILC_STATUS_ERR_NO_SERVER_PRIV
2928 "Permission denied. You are not server operator". Command may
2929 be executed only by server operator.
2931 39 SILC_STATUS_ERR_NO_ROUTER_PRIV
2933 "Permission denied. You are not SILC operator". Command may be
2934 executed only by router (SILC) operator.
2936 40 SILC_STATUS_ERR_BAD_NICKNAME
2938 "Bad nickname". Nickname requested contained illegal characters
2941 41 SILC_STATUS_ERR_BAD_CHANNEL
2943 "Bad channel name". Channel requested contained illegal characters
2946 42 SILC_STATUS_ERR_AUTH_FAILED
2948 "Authentication failed". The authentication data sent as
2949 argument were wrong and thus authentication failed.
2954 6 Security Considerations
2956 Security is central to the design of this protocol, and these security
2957 considerations permeate the specification.
2966 [SILC2] Riikonen, P., "SILC Packet Protocol", Internet Draft,
2969 [SILC3] Riikonen, P., "SILC Key Exchange and Authentication
2970 Protocols", Internet Draft, June 2000.
2972 [IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
2975 [SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
2978 [PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
2981 [SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
2984 [PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
2985 Infrastructure, Certificate and CRL Profile", RFC 2459,
2988 [Schneier] Schneier, B., "Applied Cryptography Second Edition",
2989 John Wiley & Sons, New York, NY, 1996.
2991 [Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
2994 [OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
2995 RFC 2412, November 1998.
2997 [ISAKMP] Maughan D., et al, "Internet Security Association and
2998 Key Management Protocol (ISAKMP)", RFC 2408, November
3001 [IKE] Harkins D., and Carrel D., "The Internet Key Exhange
3002 (IKE)", RFC 2409, November 1998.
3004 [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
3005 Authentication", RFC 2104, February 1997.
3018 EMail: priikone@poseidon.pspt.fi