8 .ds RF FORMFEED[Page %]
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
27 <draft-riikonen-silc-spec-00.txt>
32 This document is an Internet-Draft and is in full conformance with
33 all provisions of Section 10 of RFC 2026. Internet-Drafts are
34 working documents of the Internet Engineering Task Force (IETF), its
35 areas, and its working groups. Note that other groups may also
36 distribute working documents as Internet-Drafts.
38 Internet-Drafts are draft documents valid for a maximum of six months
39 and may be updated, replaced, or obsoleted by other documents at any
40 time. It is inappropriate to use Internet-Drafts as reference
41 material or to cite them other than as "work in progress."
43 The list of current Internet-Drafts can be accessed at
44 http://www.ietf.org/ietf/1id-abstracts.txt
46 The list of Internet-Draft Shadow Directories can be accessed at
47 http://www.ietf.org/shadow.html
49 The distribution of this memo is unlimited.
55 This memo describes a Secure Internet Live Conferencing (SILC)
56 protocol which provides secure conferencing services over insecure
57 network channel. SILC is IRC [IRC] like protocol, however, it is
58 not equivalent to IRC and does not support IRC. Strong cryptographic
59 methods are used to protect SILC packets inside SILC network. Two
60 other Internet Drafts relates very closely to this memo; SILC Packet
61 Protocol [SILC2] and SILC Key Exchange and Authentication Protocols
75 1 Introduction .................................................. 3
76 2 SILC Concepts ................................................. 3
77 2.1 SILC Network Topology ..................................... 4
78 2.2 Communication Inside a Cell ............................... 5
79 2.3 Communication in the Network .............................. 6
80 2.4 Channel Communication ..................................... 7
81 3 SILC Specification ............................................ 7
82 3.1 Client .................................................... 7
83 3.1.1 Client ID ........................................... 8
84 3.2 Server .................................................... 9
85 3.2.1 Server's Local ID List .............................. 9
86 3.2.2 Server ID ........................................... 10
87 3.2.3 SILC Server Ports ................................... 11
88 3.3 Router .................................................... 11
89 3.3.1 Router's Local ID List .............................. 11
90 3.3.2 Router's Global ID List ............................. 12
91 3.3.3 Router's Server ID .................................. 13
92 3.4 Channels .................................................. 13
93 3.4.1 Channel ID .......................................... 14
94 3.5 Operators ................................................. 14
95 3.6 SILC Commands ............................................. 15
96 3.7 SILC Packets .............................................. 15
97 3.8 Packet Encryption ......................................... 16
98 3.8.1 Determination of the Source and the Destination ..... 16
99 3.8.2 Client To Client .................................... 17
100 3.8.3 Client To Channel ................................... 18
101 3.8.4 Server To Server .................................... 19
102 3.9 Key Exchange And Authentication ........................... 19
103 3.10 Algorithms ............................................... 19
104 3.10.1 Ciphers ............................................ 19
105 3.10.2 Public Key Algorithms .............................. 20
106 3.10.3 MAC Algorithms ..................................... 20
107 3.10.4 Compression Algorithms ............................. 21
108 3.11 SILC Public Key .......................................... 21
109 4 SILC Procedures ............................................... 24
110 4.1 Creating Client Connection ................................ 24
111 4.2 Creating Server Connection ................................ 25
112 4.3 Joining to a Channel ...................................... 26
113 4.4 Channel Key Generation .................................... 27
114 4.5 Private Message Sending and Reception ..................... 27
115 4.6 Private Message Key Generation ............................ 28
116 4.7 Channel Message Sending and Reception ..................... 29
117 4.8 Session Key Regeneration .................................. 29
118 4.9 Command Sending and Reception ............................. 29
119 5 SILC Commands ................................................. 30
120 5.1 SILC Commands Syntax ...................................... 30
121 5.2 SILC Commands List ........................................ 32
122 5.3 SILC Command Status Types ................................. 53
123 5.3.1 SILC Command Status Payload ......................... 53
124 5.3.2 SILC Command Status List ............................ 54
125 6 Security Considerations ....................................... 59
126 7 References .................................................... 59
127 8 Author's Address .............................................. 60
134 Figure 1: SILC Network Topology
135 Figure 2: Communication Inside cell
136 Figure 3: Communication Between Cells
137 Figure 4: SILC Public Key
138 Figure 5: SILC Command Status Payload
144 This document describes a Secure Internet Live Conferencing (SILC)
145 protocol which provides secure conferencing services over insecure
146 network channel. SILC is IRC [IRC] like protocol, however, it is
147 not equivalent to IRC and does not support IRC.
149 Strong cryptographic methods are used to protect SILC packets inside
150 SILC network. Two other Internet Drafts relates very closely to this
151 memo; SILC Packet Protocol [SILC2] and SILC Key Exchange and
152 Authentication Protocols [SILC3].
154 The protocol uses extensively packets as conferencing protocol
155 requires message and command sending. The SILC Packet Protocol is
156 described in [SILC2] and should be read to fully comprehend this
157 document and protocol. [SILC2] also describes the packet encryption
158 and decryption in detail.
160 The security of SILC protocol and for any security protocol for that
161 matter is based on strong and secure key exchange protocol. The SILC
162 Key Exchange protocol is described in [SILC3] along with connection
163 authentication protocol and should be read to fully comprehend this
164 document and protocol.
166 The SILC protocol has been developed to work on TCP/IP network
167 protocol, although it could be made to work on other network protocols
168 with only minor changes. However, it is recommended that TCP/IP
169 protocol is used under SILC protocol. Typical implementation would
170 be made in client-server model.
176 This section describes various SILC protocol concepts that forms the
177 actual protocol, and in the end, the actual SILC network. The mission
178 of the protocol is to deliver messages from clients to other clients
179 through routers and servers in secure manner. The messages may also
180 be delivered from one client to many clients forming a group, also
183 This section does not focus to security issues, instead basic network
184 concepts are introduced to make the topology of the SILC network
189 2.1 SILC Network Topology
191 SILC network is a cellular network as opposed to tree style network
192 topology. The rationale for this is to have servers that can perform
193 specific kind of tasks what other servers cannot perform. This leads
194 to two kinds of servers; normal SILC servers and SILC routers.
196 A difference between normal server and router server is that routers
197 knows everything about everything in the network. They also do the
198 actual routing of the messages to the correct receiver. Normal servers
199 knows only about local information and nothing about global information.
200 This makes the network faster as there are less servers that needs to
201 keep global information up to date at all time.
203 This, on the other hand, leads to cellular like network, where routers
204 are in the centrum on the cell and servers are connected to the router.
206 Following diagram represents SILC network topology.
226 ---- ---- ---- ---- ---- ----
227 | S8 | S5 | S4 | | S7 | S5 | S6 |
228 ----- ---- ----- ----- ---- -----
229 | S7 | S/R1 | S2 | --- | S8 | S/R2 | S4 |
230 ---- ------ ---- ---- ------ ----
231 | S6 | S3 | S1 | | S1 | S3 | S2 | ---- ----
232 ---- ---- ---- ---- ---- ---- | S3 | S1 |
233 Cell 1. \\ Cell 2. | \\____ ----- -----
235 ---- ---- ---- ---- ---- ---- ---- ------
236 | S7 | S4 | S2 | | S1 | S3 | S2 | | S2 | S5 |
237 ----- ---- ----- ----- ---- ----- ---- ----
238 | S6 | S/R3 | S1 | --- | S4 | S/R5 | S5 | Cell 4.
239 ---- ------ ---- ---- ------ ----
240 | S8 | S5 | S3 | | S6 | S7 | S8 | ... etc ...
241 ---- ---- ---- ---- ---- ----
246 Figure 1: SILC Network Topology
249 A cell is formed when a server or servers connect to one router. In
250 SILC network normal server cannot directly connect to other normal
251 server. Normal server may only connect to SILC router which then
252 routes the messages to the other servers in the cell. Router servers
253 on the other hand may connect to other routers to form the actual SILC
254 network, as seen in above figure. However, router is also normal SILC
255 server; clients may connect to it the same way as to normal SILC
256 servers. Normal server also cannot have active connections to more
257 than one router. Normal server cannot be connected to two different
258 cells. Router servers, on the other hand, may have as many router to
259 router connections as needed.
261 There are many issues in this network topology that needs to be careful
262 about. Issues like the size of the cells, the number of the routers in
263 the SILC network and the capacity requirements of the routers. These
264 issues should be discussed in the Internet Community and additional
265 documents on the issue will be written.
269 2.2 Communication Inside a Cell
271 It is always guaranteed that inside a cell message is delivered to the
272 recipient with at most two server hops. Client who is connected to
273 server in the cell and is talking on channel to other client connected
274 to other server in the same cell, will have its messages delivered from
275 its local server first to the router of the cell, and from the router
276 to the other server in the cell. Following diagram represents this
291 Figure 2: Communication Inside cell
294 Example: Client 1. connected to Server 1. message sent to
295 Client 4. connected to Server 2. travels from Server 1.
296 first to Router which routes the message to Server 2.
297 which then sends it to the Client 4. All the other
298 servers in the cell will not see the routed message.
301 If client is connected directly to the router, as router is also normal
302 SILC server, the messages inside the cell are always delivered only with
303 one server hop. If clients communicating with each other are connected
304 to the same server, no router interaction is needed. This is the optimal
305 situation of message delivery in the SILC network.
309 2.3 Communication in the Network
311 If the message is destined to server that does not belong to local cell
312 the message is routed to the router server to which the destination
313 server belongs, if the local router is connected to destination router.
314 If there is no direct connection to the destination router, the local
315 router routes the message to its primary route. Following diagram
316 represents message sending between cells.
321 1 --- S1 S4 --- 5 S2 --- 1
322 S/R - - - - - - - - S/R
332 Figure 3: Communication Between Cells
335 Example: Client 5. connected to Server 4. in Cell 1. message sent
336 to Client 2. connected to Server 1. in Cell 2. travels
337 from Server 4. to Router which routes the message to
338 Router in Cell 2, which then routes the message to
339 Server 1. All the other servers and routers in the
340 network will not see the routed message.
343 The optimal case of message delivery from client point of view is
344 when clients are connected directly to the routers and the messages
345 are delivered from one router to the other router.
349 2.4 Channel Communication
351 Messages may be sent to group of clients as well. Sending messages to
352 many clients works the same way as sending messages point to point, from
353 message delivery point of view. Security issues are another matter
354 which are not discussed in this section.
356 Router server handles the message routing to multiple recipients. If
357 any recipient is not in the same cell as the sender the messages are
360 Server distributes the channel message to its local clients who are
361 joined to the channel. Also, router distributes the message to its
362 local clients on the channel.
366 3. SILC Specification
368 This section describes the SILC protocol. However, [SILC2] and
369 [SILC3] describes other important protocols that are part of this SILC
370 specification and must be read.
376 A client is a piece of software connecting to SILC server. SILC client
377 cannot be SILC server. Purpose of clients is to provide the user
378 interface of the SILC services for end user. Clients are distinguished
379 from other clients by unique Client ID. Client ID is a 128 bit ID that
380 is used in the communication in the SILC network. The client ID is
381 based on the nickname selected by the user. User uses logical nicknames
382 in communication which are then mapped to the corresponding Client ID.
383 Client ID's are low level identifications and must not be seen by the
386 Clients provide other information about the end user as well. Information
387 such as the nickname of the user, username and the hostname of the end
388 user and user's real name. See section 3.2 Server for information of
389 the requirements of keeping this information.
391 The nickname selected by the user is not unique in the SILC network.
392 There can be 2^8 same nicknames for one IP address. As for comparison to
393 IRC [IRC] where nicknames are unique this is a fundamental difference
394 between SILC and IRC. This causes the server names to be used along
395 with the nicknames to identify specific users when sending messages.
396 This feature of SILC makes IRC style nickname-wars obsolete as no one
397 owns their nickname; there can always be someone else with the same
398 nickname. Another difference is that there are no limit of the length
399 of the nickname in the SILC.
405 Client ID is used to identify users in the SILC network. The Client ID
406 is unique to the extent that there can be 2^128 different Client ID's.
407 Collisions are not expected to happen. The Client ID is defined as
411 128 bit Client ID based on IPv4 addresses:
413 32 bit ServerID IP address (bits 1-32)
415 88 bit Truncated MD5 hash value of the nickname
417 o Server ID IP address - Indicates the server where this
418 client is coming from. The IP address hence equals the
419 server IP address where to the client has connected.
421 o Random number - Random number to further unify the
422 Client ID. This makes it possible to have 2^8 same
423 nicknames from the same server IP address.
425 o MD5 hash - MD5 hash value of the nickname is truncated
426 taking 88 bits from the start of the hash value. This
427 hash value is used to search the user's Client ID from
431 Collisions could occur when more than 2^8 clients using same nickname
432 from the same server IP address is connected to the SILC network.
433 Server must be able to handle this situation by refusing to accept
434 anymore of that nickname.
436 Another possible collision may happen with the truncated hash value of
437 the nickname. It could be possible to have same truncated hash value for
438 two different nicknames. However, this is not expected to happen nor
439 cause any problems if it would occur. Nicknames are usually logical and
440 it is unlikely to have two distinct logical nicknames produce same
441 truncated hash value.
447 Servers are the most important parts of the SILC network. They form the
448 basis of the SILC, providing a point to which clients may connect to.
449 There are two kinds of servers in SILC; normal servers and router servers.
450 This section focuses on the normal server and router server is described
451 in the section 3.3 Router.
453 Normal servers may not directly connect to other normal server. Normal
454 servers may only directly connect to router server. If the message sent
455 by the client is destined outside the local server it is always sent to
456 the router server for further routing. Server may only have one active
457 connection to router on same port. Normal server may not connect to other
458 cell's router except in situations where its cell's router is unavailable.
460 Servers and routers in the SILC network are considered to be trusted.
461 With out a doubt, servers that are set to work on ports above 1023 are
462 not considered to be trusted. Also, the service provider acts important
463 role in the server's trustworthy.
467 3.2.1 Server's Local ID List
469 Normal server keeps various information about the clients and their end
470 users connected to it. Every normal server must keep list of all locally
471 connected clients, Client ID's, nicknames, usernames and hostnames and
472 user's real name. Normal servers only keeps local information and it
473 does not keep any global information. Hence, normal servers knows only
474 about their locally connected clients. This makes servers efficient as
475 they don't have to worry about global clients. Server is also responsible
476 of creating the Client ID's for their clients.
478 Normal server also keeps information about locally created channels and
488 Hence, local list for normal server includes:
491 server list - Router connection
499 client list - All clients in server
507 channel list - All channels in server
510 o Client ID's on channel
511 o Client ID modes on channel
520 Servers are distinguished from other servers by unique 64 bit Server ID.
521 The Server ID is used in the SILC to route messages to correct servers.
522 Server ID's also provide information for Client ID's, see section 3.1.1
523 Client ID. Server ID is defined as follows.
526 64 bit Server ID based on IPv4 addresses:
528 32 bit IP address of the server
532 o IP address of the server - This is the real IP address of
535 o Port - This is the port the server is binded to.
537 o Random number - This is used to further unify the Server ID.
540 Collisions are not expected to happen in any conditions. The Server ID
541 is always created by the server itself and server is resposible of
542 distributing it to the router.
546 3.2.3 SILC Server Ports
548 SILC uses currently TCP port 334 on SILC network. However, this is not
549 official port assigned for SILC. Official port has been requested by
552 If there are needs to create new SILC networks in the future the port
553 numbers must be officially assigned by the IANA. Most convenience case
554 would be to assign port numbers upwards from 334.
556 Server on network above privileged ports (>1023) should not be trusted
557 as they could have been set up by untrusted party.
563 Router server in SILC network is responsible for keeping the cell together
564 and routing messages to other servers and to other routers. Router server
565 is also a normal server thus clients may connect to it as it would be
566 just normal SILC server.
568 However, router servers has a lot of important tasks that normal servers
569 do not have. Router server knows everything about everything in the SILC.
570 They know all clients currently on SILC, all servers and routers and all
571 channels in SILC. Routers are the only servers in SILC that care about
572 global information and keeping them up to date at all time. And, this
573 is what they must do.
577 3.3.1 Router's Local ID List
579 Router server as well must keep local list of connected clients and
580 locally created channels. However, this list is extended to include all
581 the informations of the entire cell, not just the server itself as for
584 However, on router this list is a lot smaller since routers do not keep
585 information about user's nickname, username and hostname and real name
586 since these are not needed by the router. Router keeps only information
593 Hence, local list for router includes:
596 server list - All servers in the cell
603 client list - All clients in the cell
606 channel list - All channels in the cell
608 o Client ID's on channel
609 o Client ID modes on channel
614 Note that locally connected clients and other information include all the
615 same information as defined in section section 3.2.1 Server's Local ID
620 3.3.2 Router's Global ID List
622 Router server must also keep global list. Normal servers do not have
623 global list as they know only about local information. Global list
624 includes all the clients on SILC, their Client ID's, all created channels
625 and their Channel ID's and all servers and routers on SILC and their
626 Server ID's. That is said, global list is for global information and the
627 list must not include the local information already on the router's local
630 Note that the global list does not include information like nicknames,
631 usernames and hostnames or user's real names. Router does not keep
632 these informations as they are not needed by the router. This
633 information is available from the client's server which maybe queried
636 Hence, global list includes:
639 server list - All servers in SILC
645 client list - All clients in SILC
648 channel list - All channels in SILC
650 o Client ID's on channel
651 o Client ID modes on channel
656 3.3.3 Router's Server ID
658 Router's Server ID's are equivalent to normal Server ID's. As routers
659 are normal servers as well same types of ID's applies for routers as well.
660 Thus, see section 3.2.2 Server ID. Server ID's for routers are always
661 created by the remote router where the router is connected to.
667 A channel is a named group of one or more clients which will all receive
668 messages addressed to that channel. The channel is created when first
669 client requests JOIN command to the channel, and the channel ceases to
670 exist when the last client leaves it. When channel exists, any client
671 can reference it using the name of the channel.
673 Channel names are unique although the real uniqueness comes from 64 bit
674 Channel ID that unifies each channel. However, channel names are still
675 unique and no two global channels with same name may exist. Channel name
676 is a string which begins with `#' character. There is no limit on the
677 length of the channel name. Channel names may not contain any spaces
678 (` '), any non-printable ASCII characters, commas (`,') and wildcard
681 Channels can have operators that can administrate the channel and
682 operate all of its modes. Following operators on channel exist on SILC
686 o Channel founder - When channel is created the joining client becomes
687 channel founder. Channel founder is channel operator with some more
688 privileges. Basically, channel founder can fully operate the channel
689 and all of its modes. The privileges are limited only to the particular
690 channel. There can be only one channel founder per channel. Channel
691 founder supersedes channel operator's privileges.
693 Channel founder privileges cannot be removed by any other operator on
694 channel. When channel founder leaves the channel there is no channel
695 founder on the channel. Channel founder also cannot be removed by
696 force from the channel.
698 o Channel operator - When client joins to channel that has not existed
699 previously it will become automatically channel operator (and channel
700 founder discussed above). Channel operator is able administrate the
701 channel, set some modes on channel, remove a badly behaving client from
702 the channel and promote other clients to become channel operator.
703 The privileges are limited only to the particular channel.
705 Normal channel user may be promoted (opped) to channel operator
706 gaining channel operator privileges. Channel founder or other channel
707 operator may also demote (deop) channel operator to normal channel
715 Channels are distinguished from other channels by unique Channel ID.
716 The Channel ID is a 64 bit ID and collisions are not expected to happen
717 in any conditions. Channel names are just for logical use of channels.
718 The Channel ID is created by the server where the channel is created.
719 The Channel ID is defined as follows.
722 64 bit Channel ID based on IPv4 addresses:
724 32 bit Router's Server ID IP address (bits 1-32)
725 16 bit Router's Server ID port (bits 33-48)
728 o Router's Server ID IP address - Indicates the IP address of
729 the router of the cell where this channel is created. This is
730 taken from the router's Server ID. This way SILC router knows
731 where this channel resides in the SILC network.
733 o Router's Server ID port - Indicates the port of the channel on
734 the server. This is taken from the router's Server ID.
736 o Random number - To further unify the Channel ID. This makes
737 sure that there are no collisions. This also means that
738 in a cell there can be 2^16 channels.
745 Operators are normal users with extra privileges to their server or
746 router. Usually these people are SILC server and router administrators
747 that take care of their own server and clients on them. The purpose of
748 operators is to administrate the SILC server or router. However, even
749 an operator with highest privileges is not able to enter invite-only
750 channel, to gain access to the contents of a encrypted and authenticated
751 packets traveling in the SILC network or to gain channel operator
752 privileges on public channels without being promoted. They have the
753 same privileges as everyone else except they are able to administrate
754 their server or router.
760 Commands are very important part on SILC network especially for client
761 which uses commands to operate on the SILC network. Commands are used
762 to set nickname, join to channel, change modes and many other things.
764 Client usually sends the commands and server replies by sending a reply
765 packet to the command. Server may also send commands usually to serve
766 the original client's request. However, server may not send command
767 to client and there are some commands that server must not send. Server
768 is also able to send the forwarded command packets. For example,
769 SILC_COMMAND_JOIN is always forwarded packet. See [SILC2] for more
770 about packet forwarding.
772 Note that the command reply is usually sent only after client has sent
773 the command request but server is allowed to send command reply packet
774 to client even if client has not requested the command. Client may,
775 however, choose not to accept the command reply, but there are some
776 command replies that the client should accept. Example of a such
777 command reply is reply to SILC_COMMAND_CMODE command that the server
778 uses to distribute the channel mode on all clients on the channel
779 when the mode has changed.
781 It is expected that some of the commands may be miss-used by clients
782 resulting various problems on the server side. Every implementation
783 should assure that commands may not be executed more than once, say,
784 in two (2) seconds. This should be sufficient to prevent the miss-use
787 SILC commands are described in section 5 SILC Commands.
793 Packets are naturally the most important part of the protocol and the
794 packets are what actually makes the protocol. Packets in SILC network
795 are always encrypted using, usually, the shared secret session key
796 or some other key, for example, channel key, when encrypting channel
797 messages. The SILC Packet Protocol is a wide protocol and is described
798 in [SILC2]. This document does not define or describe details of
805 3.8 Packet Encryption
807 All packets passed in SILC network must be encrypted. This section
808 defines how packets must be encrypted in the SILC network. The detailed
809 description of the actual encryption process of the packets are
810 described in [SILC2].
812 Client and its server shares secret symmetric session key which is
813 established by the SILC Key Exchange Protocol, described in [SILC3].
814 Every packet sent from client to server, with exception of packets for
815 channels, are encrypted with this session key.
817 Channels has their own key that are shared by every client on the channel.
818 However, the channel keys are cell specific thus one cell does not know
819 the channel key of the other cell, even if that key is for same channel.
820 Channel key is also known by the routers and all servers that has clients
821 on the channel. However, channels may have channel private keys that
822 are entirely local setting for client. All clients on the channel must
823 know the channel private key before hand to be able to talk on the
824 channel. In this case, no server or router knows the key for channel.
826 Server shares secret symmetric session key with router which is
827 established by the SILC Key Exchange Protocol. Every packet passed from
828 server to router, with exception of packets for channels, are encrypted
829 with the shared session key. Same way, router server shares secret
830 symmetric key with its primary route. However, every packet passed
831 from router to other router, including packets for channels, are
832 encrypted with the shared session key. Every router connection has
833 their own session keys.
837 3.8.1 Determination of the Source and the Destination
839 The source and the destination of the packet needs to be determined
840 to be able to route the packets to correct receiver. This information
841 is available in the SILC Packet Header which is included in all packets
842 sent in SILC network. The SILC Packet Header is described in [SILC2].
844 The header is always encrypted with the session key who is next receiver
845 of the packet along the route. The receiver of the packet, for example
846 a router along the route, is able to determine the sender and the
847 destination of the packet by decrypting the SILC Packet Header and
848 checking the ID's attached to the header. The ID's in the header will
849 tell to where the packet needs to be sent and where it is coming from.
851 The header in the packet does not change during the routing of the
852 packet. The original sender, for example client, assembles the packet
853 and the packet header and server or router between the sender and the
854 receiver must not change the packet header.
856 Note that the packet and the packet header may be encrypted with
857 different keys. For example, packets to channels are encrypted with
858 the channel key, however, the header is encrypted with the session key
859 as described above. However, the header and the packet may be encrypted
860 with same key. This is case, for example, with command packets.
864 3.8.2 Client To Client
866 Process of message delivery and encryption from client to another
867 client is as follows.
869 Example: Private message from client to another client on different
870 servers. Clients do not share private message delivery
871 keys; normal session keys are used.
873 o Client 1. sends encrypted packet to its server. The packet is
874 encrypted with the session key shared between client and its
877 o Server determines the destination of the packet and decrypts
878 the packet. Server encrypts the packet with session key shared
879 between the server and its router, and sends the packet to the
882 o Router determines the destination of the packet and decrypts
883 the packet. Router encrypts the packet with session key
884 shared between the router and the destination server, and sends
885 the packet to the server.
887 o Server determines the client to which the packet is destined
888 to and decrypts the packet. Server encrypts the packet with
889 session key shared between the server and the destination client,
890 and sends the packet to the client.
892 o Client 2. decrypts the packet.
895 Example: Private message from client to another client on different
896 servers. Clients has established secret shared private
897 message delivery key with each other and that is used in
898 the message encryption.
900 o Client 1. sends encrypted packet to its server. The packet is
901 encrypted with the private message delivery key shared between
904 o Server determines the destination of the packet and sends the
905 packet to the router.
907 o Router determines the destination of the packet and sends the
908 packet to the server.
910 o Server determines the client to which the packet is destined
911 to and sends the packet to the client.
913 o Client 2. decrypts the packet with the secret shared key.
916 If clients share secret key with each other the private message
917 delivery is much simpler since servers and routers between the
918 clients do not need to decrypt and re-encrypt the packet.
920 The process for clients on same server is much simpler as there are
921 no need to send the packet to the router. The process for clients
922 on different cells is same as above except that the packet is routed
923 outside the cell. The router of the destination cell routes the
924 packet to the destination same way as described above.
928 3.8.3 Client To Channel
930 Process of message delivery from client on channel to all the clients
933 Example: Channel of four users; two on same server, other two on
934 different cells. Client sends message to the channel.
936 o Client 1. encrypts the packet with channel key and sends the
937 packet to its server.
939 o Server determines local clients on the channel and sends the
940 packet to the Client on the same server. Server then sends
941 the packet to its router for further routing.
943 o Router determines local clients on the channel, if found
944 sends packet to the local clients. Router determines global
945 clients on the channel and sends the packet to its primary
946 router or fastest route.
948 o (Other router(s) do the same thing and sends the packet to
951 o Server determines local clients on the channel and sends the
952 packet to the client.
954 o All clients receiving the packet decrypts the packet.
958 3.8.4 Server To Server
960 Server to server packet delivery and encryption is described in above
961 examples. Router to router packet delivery is analogous to server to
962 server. However, some packets, such as channel packets, are processed
963 differently. These cases are described later in this document and
964 more in detail in [SILC2].
968 3.9 Key Exchange And Authentication
970 Key exchange is done always when for example client connects to server
971 but also when server and router and router and router connects to each
972 other. The purpose of key exchange protocol is to provide secure key
973 material to be used in the communication. The key material is used to
974 derive various security parameters used to secure SILC packets. The
975 SILC Key Exchange protocol is described in detail in [SILC3].
977 Authentication is done after key exchange protocol has been successfully
978 completed. The purpose of authentication is to authenticate for example
979 client connecting to the server. However, Usually clients are accepted
980 to connect to server without explicit authentication. Servers are
981 required use authentication protocol when connecting. The authentication
982 may be based on passphrase (pre-shared-secret) or public key. The
983 connection authentication protocol is described in detail in [SILC3].
989 This section defines all the allowed algorithms that can be used in
990 the SILC protocol. This includes mandatory cipher, mandatory public
991 key algorithm and MAC algorithms.
997 Cipher is the encryption algorithm that is used to protect the data
998 in the SILC packets. See [SILC2] of the actual encryption process and
999 definition of how it must be done. SILC has a mandatory algorithm that
1000 must be supported in order to be compliant with this protocol.
1007 Following ciphers are defined in SILC protocol:
1010 blowfish-cbc Blowfish in CBC mode (mandatory)
1011 twofish-cbc Twofish in CBC mode (optional)
1012 rc6-cbc RC6 in CBC mode (optional)
1013 rc5-cbc RC5 in CBC mode (optional)
1014 mars-cbc Mars in CBC mode (optional)
1015 none No encryption (optional)
1019 All algorithms must use minimum of 128 bit key, by default. Several
1020 algorithms, however, supports longer keys and it is recommended to use
1021 longer keys if they are available.
1023 Algorithm none does not perform any encryption process at all and
1024 thus is not recommended to be used. It is recommended that no client
1025 or server implementation would accept none algorithms except in special
1028 Additional ciphers may be defined to be used in SILC by using the
1029 same name format as above.
1033 3.10.2 Public Key Algorithms
1035 Public keys are used in SILC to authenticate entities in SILC network
1036 and to perform other tasks related to public key cryptography. The
1037 public keys are also used in the SILC Key Exchange protocol [SILC3].
1039 Following public key algorithms are defined in SILC protocol:
1046 Both of the algorithms are described in [Scheneir] and [Menezes].
1048 Additional public key algorithms may be defined to be used in SILC.
1052 3.10.3 MAC Algorithms
1054 Data integrity is protected by computing a message authentication code
1055 (MAC) of the packet data. See [SILC2] for details how to compute the
1062 Following MAC algorithms are defined in SILC protocol:
1065 hmac-sha1 HMAC-SHA1, length = 20 (mandatory)
1066 hmac-md5 HMAC-MD5, length = 16 (optional)
1067 none No MAC (optional)
1070 The none MAC is not recommended to be used as the packet is not
1071 authenticated when MAC is not computed. It is recommended that no
1072 client or server would accept none MAC except in special debugging
1075 The HMAC algorithm is described in [HMAC] and hash algorithms that
1076 are used as part of the HMACs are described in [Scheneir] and in
1079 Additional MAC algorithms may be defined to be used in SILC.
1083 3.10.4 Compression Algorithms
1085 SILC protocol supports compression that may be applied to unencrypted
1086 data. It is recommended to use compression on slow links as it may
1087 significantly speed up the data transmission. By default, SILC does not
1088 use compression which is the mode that must be supported by all SILC
1091 Following compression algorithms are defined:
1094 none No compression (mandatory)
1095 zlib GBU ZLIB (LZ77) compression (optional)
1098 Additional compression algorithms may be defined to be used in SILC.
1102 3.11 SILC Public Key
1104 This section defines the type and format of the SILC public key. All
1105 implementations must support this public key type. See [SILC3] for
1106 other optional public key and certificate types allowed in SILC
1107 protocol. Public keys in SILC may be used to authenticate entities
1108 and to perform other tasks related to public key cryptography.
1110 The format of the SILC Public Key is as follows:
1121 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
1122 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1123 | Public Key Length |
1124 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1125 | Algorithm Name Length | |
1126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1130 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1131 | Identifier Length | |
1132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1140 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1144 Figure 4: SILC Public Key
1148 o Public Key Length (4 bytes) - Indicates the full length
1149 of the public key, not including this field.
1151 o Algorithm Name Length (2 bytes) - Indicates the length
1152 of the Algorithm Length field, not including this field.
1154 o Algorithm name (variable length) - Indicates the name
1155 of the public key algorithm that the key is. See the
1156 section 3.10.2 Public Key Algorithms for defined names.
1158 o Identifier Length (2 bytes) - Indicates the length of
1159 the Identifier field, not including this field.
1161 o Identifier (variable length) - Indicates the identifier
1162 of the public key. This data can be used to identify
1163 the owner of the key. The identifier is of following
1167 HN Host name or IP address
1174 Examples of an identifier:
1176 `UN=priikone, HN=poseidon.pspt.fi, E=priikone@poseidon.pspt.fi'
1178 `UN=sam, HN=dummy.fi, RN=Sammy Sam, O=Company XYZ, C=Finland'
1180 At least user name (UN) and host name (HN) must be provided as
1181 identifier. The fields are separated by commas (`,'). If
1182 comma is in the identifier string it must be written as `\\,',
1183 for example, `O=Company XYZ\\, Inc.'.
1185 o Public Data (variable length) - Includes the actual
1186 public data of the public key.
1188 The format of this field for RSA algorithm is
1197 The format of this field for DSS algorithm is
1209 The variable length fields are multiple precession
1210 integers encoded as strings in both examples.
1212 Other algorithms must define their own type of this
1213 field if they are used.
1216 All fields in the public key are in MSB (most significant byte first)
1223 This section describes various SILC procedures such as how the
1224 connections are created and registered, how channels are created and
1225 so on. The section describes the procedures only generally as details
1226 are described in [SILC2] and [SILC3].
1230 4.1 Creating Client Connection
1232 This section descibres the procedure when client connects to SILC server.
1233 When client connects to server the server must perform IP address lookup
1234 and reverse IP address lookup to assure that the origin host really is
1235 who it claims to be. Client, host, connecting to server must have
1236 both valid IP address and fully qualified domain name (FQDN).
1238 After that client and server performs SILC Key Exchange protocol which
1239 will provide the key material used later in the communication. The
1240 key exchange protocol must be completed successfully before the connection
1241 registration may continue. The SILC Key Exchange protocol is described
1244 Typical server implementation would keep a list of connections that it
1245 allows to connect to the server. The implementation would check, for
1246 example, the connecting client's IP address from the connection list
1247 before the SILC Key Exchange protocol has been started. Reason for
1248 this is that if the host is not allowed to connect to the server there
1249 is no reason to perform a key exchange protocol.
1251 After successful key exchange protocol the client and server performs
1252 connection authentication protocol. The purpose of the protocol is to
1253 authenticate the client connecting to the server. Flexible
1254 implementation could also accept the client to connect to the server
1255 without explicit authentication. However, if authentication is
1256 desired for a specific client it may be based on passphrase or
1257 public key authentication. If authentication fails the connection
1258 must be terminated. The connection authentication protocol is described
1261 After successful key exchange and authentication protocol the client
1262 registers itself by sending SILC_PACKET_NEW_CLIENT packet to the
1263 server. This packet includes various information about the client
1264 that the server uses to create the client. Server creates the client
1265 and sends SILC_PACKET_NEW_ID to the client which includes the created
1266 Client ID that the client must start using after that. After that
1267 all SILC packets from the client must have the Client ID as the
1268 Source ID in the SILC Packet Header, described in [SILC2].
1270 Client must also get the server's Server ID that is to be used as
1271 Destination ID in the SILC Packet Header when communicating with
1272 the server (for example when sending commands to the server). The
1273 ID may be resolved in two ways. Client can take the ID from an
1274 previously received packet from server that must include the ID,
1275 or to send SILC_COMMAND_INFO command and receive the Server ID as
1278 Server may choose not to use the information received in the
1279 SILC_PACKET_NEW_CLIENT packet. For example, if public key or
1280 certificate were used in the authentication, server may use those
1281 informations rather than what it received from client. This is suitable
1282 way to get the true information about client if it is available.
1284 The nickname of client is initially set to the username sent in the
1285 SILC_PACKET_NEW_CLIENT packet. User should set the nickname to more
1286 suitable by sending SILC_COMMAND_NICK command. However, this is not
1287 required as part of registration process.
1289 Server must also distribute the information about newly registered
1290 client to its router (or if the server is router, to all routers in
1291 the SILC network). More information about this in [SILC2].
1295 4.2 Creating Server Connection
1297 This section descibres the procedure when server connects to its
1298 router (or when router connects to other router, the cases are
1299 equivalent). The procedure is very much alike when client connects
1300 to the server thus it is not repeated here.
1302 One difference is that server must perform connection authentication
1303 protocol with proper authentication. Proper authentication is based
1304 on passphrase or public key authentication.
1306 After server and router has successfully performed the key exchange
1307 and connection authentication protocol, the server register itself
1308 to the router by sending SILC_PACKET_NEW_SERVER packet. This packet
1309 includes the server's Server ID that it has created by itself and
1310 other relevant information about the server.
1312 After router has received the SILC_PACKET_NEW_SERVER packet it
1313 distributes the information about newly registered server to all routers
1314 in the SILC network. More information about this in [SILC2].
1316 As client needed to resolve the destination ID this must be done by the
1317 server that connected to the router, as well. The way to resolve it is
1318 to get the ID from previously received packet. Server must also start
1319 using its own Server ID as Source ID in SILC Packet Header and the
1320 router's Server ID as Destination when communicating with the router.
1322 If the server has already connected clients and locally created
1323 channels the server must distribute these informations to the router.
1324 The distribution is done by sending packet SILC_PACKET_NEW_CHANNEL.
1325 See [SILC2] for more information on this.
1329 4.3 Joining to a Channel
1331 This section describes the procedure when client joins to a channel.
1332 Client may join to channel by sending command SILC_COMMAND_JOIN to the
1333 server. If the receiver receiving join command is normal server the
1334 server must check its local list whether this channel already exists
1335 locally. This would indicate that some client connected to the server
1336 has already joined to the channel. If this is case the client is
1337 joined to the client, new channel key is created and information about
1338 newly joined channel is sent to the router. The new channel key is
1339 also distributed to the router and to all clients on the channel.
1341 If the channel does not exist in the local list the command must be
1342 fowarded to the router which will then perform the actual joining
1343 procedure. When server receives the reply to the command from the
1344 router it must be distributed to the client who sent the command
1345 originally. Server will also receive the channel key from the server
1346 that it must distribute to the client who originally requested the
1347 join command. The server must also save the channel key.
1349 If the receiver of the join command is router it must first check its
1350 local list whether anyone in the cell has already joined to the channel.
1351 If this is the case the client is joined to the channel and reply is
1352 sent to the client. If the command was sent by server the command reply
1353 is sent to the server who sent it. Then the router must also create
1354 new channel key and distribute it to all clients on the channel and
1355 all servers that has clients on the channel.
1357 If the channel does not exist on the router's local list it must
1358 check the global list whether the channel exists at all. If it does
1359 the client is joined to the channel as described previously. If
1360 the channel does not exist the channel is created and the client
1361 is joined to the channel. The channel key is also created and
1362 distributed as previously described. The client joining to the created
1363 channel is made automatically channel founder and both channel founder
1364 and channel operator privileges is set for the client.
1366 When the router joins the client to the channel it must send
1367 information about newly joined client to all routers in the SILC
1368 network. Also, if the channel was created in the process, information
1369 about newly created channel must also be distributed to all routers.
1370 The distribution of newly created channel is done by sending packet
1371 SILC_PACKET_NEW_CHANNEL.
1373 It is important to note that new channel key is created always when
1374 new client joins to channel, whether the channel has existed previously
1375 or not. This way the new client on the channel is not able to decrypt
1376 any of the old traffic on the channel.
1378 Client who receives the reply to the join command must start using
1379 the received Channel ID in the channel message communication thereafter.
1380 However, client must not start communicating on the channel before
1381 it has received the packet SILC_PACKET_CHANNEL_KEY.
1383 If client wants to know the other clients currently on the channel
1384 the client must send SILC_COMMAND_NAMES command to receive a list of
1385 channel users. Server implementation, however, may send command reply
1386 packet to SILC_COMMAND_NAMES command after client has joined to the
1387 channel even if the client has not sent the command.
1391 4.4 Channel Key Generation
1393 Channel keys are created by router who creates the channel by taking
1394 enough randomness from cryptographically strong random number generator.
1395 The key is generated always when channel is created, when new client
1396 joins a channel and after the key has expired. Key could expire for
1399 The key must also be re-generated whenever some client leaves a channel.
1400 In this case the key is created from scratch by taking enough randomness
1401 from the random number generator. After that the key is distributed to
1402 all clients on the channel. However, channel keys are cell specific thus
1403 the key is created only on the cell where the client, who leaved the
1404 channel, exists. While the server or router is creating the new channel
1405 key, no other client may join to the channel. Messages that are sent
1406 while creating the new key are still processed with the old key. After
1407 server has sent the SILC_PACKET_CHANNEL_KEY packet must client start
1408 using the new key. If server creates the new key the server must also
1409 send the new key to its router. See [SILC2] on more information about
1410 how channel messages must be encrypted and decrypted when router is
1415 4.5 Private Message Sending and Reception
1417 Private messages are sent point to point. Client explicitly destines
1418 a private message to specific client that is delivered to only to that
1419 client. No other client may receive the private message. The receiver
1420 of the private message is destined in the SILC Packet Header as any
1421 other packet as well.
1423 If the sender of a private message does not know the receiver's Client
1424 ID, it must resolve it from server. There are two ways to resolve the
1425 client ID from server; it is recommended that client ipmlementations
1426 send SILC_COMMAND_IDENTIFY command to receive the Client ID. Client
1427 may also send SILC_COMMAND_WHOIS command to receive the Client ID.
1428 If the sender has received earlier a private message from the receiver
1429 it should have cached the Client ID from the SILC Packet Header.
1431 Receiver of a private message should not explicitly trust the nickname
1432 that it receives in the Private Message Payload, described in [SILC2].
1433 Implementations could resolve the nickname from server, as described
1434 previously, and compare the received Client ID and the SILC Packet
1435 Header's Client ID. The nickname in the payload is merely provided
1436 to be displayed for end user.
1438 See [SILC2] for describtion of private message encryption and decryption
1443 4.6 Private Message Key Generation
1445 Private message may be protected by key generated by client. The key
1446 may be generated and sent to the other client by sending packet
1447 SILC_PACKET_PRIVATE_MESSAGE_KEY which travels through the network
1448 and is secured by session keys. After that the private message key
1449 is used in the private message communication between those clients.
1450 See more information about how this works technically in [SILC2].
1452 Other choice is to entirely use keys that are not sent through
1453 the SILC network at all. This significantly adds security. This key
1454 would be pre-shared-key that is known by both of the clients. Both
1455 agree about using the key and starts sending packets that indicate
1456 that the private message is secured using private message key. This
1457 is the technical aspect mentioned previously that is described
1460 If the private message keys are not set to be used, which is the
1461 case by default in SILC, the private messages are secured by using
1462 normal session keys established by SILC Key Exchange protocol.
1468 4.7 Channel Message Sending and Reception
1470 Channel messages are delivered to group of users. The group forms a
1471 channel and all clients on the channel receives messages sent to the
1474 Channel messages are destined to channel by specifying the Channel ID
1475 as Destination ID in the SILC Packet Header. The server must then
1476 distribute the message to all clients on the channel by sending the
1477 channel message destined explicitly to a client on the channel.
1479 See [SILC2] for describtion of channel message encryption and decryption
1484 4.8 Session Key Regeneration
1486 Session keys should be regenerated peridiocally, say, once in an hour.
1487 The re-key process is started by sending SILC_PACKET_REKEY packet to
1488 other end, to indicate that re-key must be performed.
1490 If perfect forward secrecy (PFS) flag was selected in the SILC Key
1491 Exchange protocol [SILC3] the re-key must cause new key exchange with
1492 SKE protocol. In this case the protocol is secured with the old key
1493 and the protocol results to new key material. See [SILC3] for more
1494 information. After the SILC_PACKET_REKEY packet is sent the sender
1495 will perform the SKE protocol.
1497 If PFS flag was not set, which is the default case, then re-key is done
1498 without executing SKE protocol. In this case, the new key is created by
1499 hashing the old key with hash function selected earlier in the SKE
1500 protocol. If the digest length of the hash function is too short for the
1501 key, then the key is distributed as described in section Processing the
1502 Key Material in [SILC3]. After both parties has regenerated the session
1503 key, both send SILC_PACKET_REKEY_DONE packet to each other. These packets
1504 are still secured with the old key. After these packets, following
1505 packets must be protected with the new key.
1509 4.9 Command Sending and Reception
1511 Client usually sends the commands in the SILC network. In this case
1512 the client simply sends the command packet to server and the server
1513 processes it and replies with command reply packet.
1515 However, if the server is not able to process the command, it is usually
1516 sent to the server's router. This is case for example with commands such
1517 as, SILC_COMMAND_JOIN and SILC_COMMAND_WHOIS commands. However, there
1518 are other commands as well. For example, if client sends the WHOIS
1519 command requesting specific information about some client the server must
1520 send the WHOIS command to router so that all clients in SILC network
1521 are searched. The router, on the other hand, sends the WHOIS command
1522 to further to receive the exact information about the requested client.
1523 The WHOIS command travels all the way to the server who owns the client
1524 and it replies with command reply packet. Finally, the server who
1525 sent the command receives the command reply and it must be able to
1526 determine which client sent the original command. The server then
1527 sends command reply to the client. Implementations should have some
1528 kind of cache to handle, for example, WHOIS information. Servers
1529 and routers along the route could all cache the information for faster
1530 referencing in the future.
1532 The commands sent by server may be sent hop by hop until someone is able
1533 to process the command. However, it is preferred to destine the command
1534 as precisely as it is possible. In this case, other routers en route
1535 must route the command packet by checking the true sender and true
1536 destination of the packet. However, servers and routers must not route
1537 command reply packets to clients coming from other server. Client
1538 must not accept command reply packet originated from anyone else but
1539 from its own server.
1546 5.1 SILC Commands Syntax
1548 This section briefly describes the syntax of the command notions
1549 in this document. Every field in command is separated from each
1550 other by whitespaces (` ') indicating that each field is independent
1551 argument and each argument must have own Command Argument Payload.
1552 The number of maximum arguments are defined with each command
1553 separately. The Command Argument Payload is described in [SILC2].
1555 Every command defines specific number for each argument. Currently,
1556 they are defined in ascending order; first argument has number one
1557 (1), second has number two (2) and so on. This number is set into the
1558 Argument Type field in the Command Argument Payload. This makes it
1559 possible to send the arguments in free order as the number must be
1560 used to identify the type of the argument. This makes is it also
1561 possible to have multiple optional arguments in commands and in
1562 command replies. The number of argument is marked in parentheses
1563 before the actual argument.
1570 Example: Arguments: (1) <nickname> (2) <username@host>
1574 Every command replies with Status Payload. This payload tells the
1575 sender of the command whether the command was completed succefully or
1576 whether there was an error. If error occured the payload includes the
1577 error type. In the next section the Status Payload is not described
1578 as it is common to all commands and has been described here. Commands
1579 may reply with other arguments as well. These arguments are command
1580 specific and are described in the next section.
1589 Arguments: (1) <nickname>[@<server>] (2) <message>
1592 The command has maximum of 3 arguments. However, only first
1593 and second arguments are mandatory.
1595 First argument <nickname> is mandatory but may have optional
1596 <nickname@server> format as well. Second argument is mandatory
1597 <message> argument. Third argument is optional <count> argument.
1599 The numbers in parentheses are the argument specific numbers
1600 that specify the type of the argument in Command Argument Payload.
1601 The receiver always knows that, say, argument number two (2) is
1602 <message> argument, regardles of the ordering of the arguments in
1603 the Command Payload.
1605 Reply messages to the command:
1608 Arguments: (1) <Status Payload> (2) [<channel list>]
1609 (3) <idle time> (4) [<away message>]
1611 This command may reply with maximum of 4 arguments. However,
1612 only the first and third arguments are mandatory. The numbers
1613 in the parentheses have the same meaning as in the upper
1614 command sending specification.
1616 Every command reply with <Status Payload>, it is mandatory
1617 argument for all command replies and for this reason it is not
1618 described in the command reply descriptions.
1625 SILC_STATUS_ERR_TOO_MANY_TARGETS
1626 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1627 SILC_STATUS_ERR_NO_SUCH_NICK
1629 Every command reply also defines set of status message that it
1630 may return inside the <Status Payload>. All status messages
1631 are defined in the section 5.3 SILC Command Status Types.
1636 5.2 SILC Commands List
1638 This section lists all SILC commands, however, it is expected that a
1639 implementation and especially client implementation has many more
1640 commands that has only local affect. These commands are official
1641 SILC commands that has both client and server sides and cannot be
1642 characterized as local commands.
1644 List of all defined commands in SILC follows.
1649 None. This is reserved command and must not be sent.
1652 2 SILC_COMMAND_WHOIS
1655 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1657 Whois. Whois command is used to query various information about
1658 specific user. The user maybe requested by their nickname and
1659 server name. The query may find multiple matching users as
1660 there are no unique nicknames in the SILC. The <count> option
1661 maybe given to narrow down the number of accepted results. If
1662 this is not defined there are no limit of accepted results.
1663 The query may also be narrowed down by defining the server name
1666 To prevent miss-use of this service wildcards in the nickname
1667 or in the servername are not permitted. It is not allowed
1668 to request all users on some server. The WHOIS requests must
1669 be based on specific nickname request.
1671 The WHOIS request must be always forwarded to router by server
1672 so that all users are searched. However, the server still must
1673 search its locally connected clients. The server must send
1674 this command to the server who owns the requested client. That
1675 server must reply to the command.
1677 Reply messages to the command:
1680 Arguments: (1) <Status Payload> (2) <Client ID>
1681 (3) <nickname>[@<server>] (4) <username@host>
1682 (5) <real name> (6) [<channel list>]
1685 This command may reply with several command reply messages to
1686 form a list of results. In this case the status payload will
1687 include STATUS_LIST_START status in the first reply and
1688 STATUS_LIST_END in the last reply to indicate the end of the
1689 list. If there are only one reply the status is set to normal
1692 The command replies include the Client ID of the nickname,
1693 nickname and servername, username and hostnamea and users real
1694 name. Client should process these replies only after the last
1695 reply has been received with the STATUS_LIST_END status. If the
1696 <count> option were defined in the query there will be only
1697 <count> many replies from the server.
1702 SILC_STATUS_LIST_START
1703 SILC_STATUS_LIST_END
1704 SILC_STATUS_ERR_NO_SUCH_NICK
1705 SILC_STATUS_ERR_WILDCARDS
1706 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1707 SILC_STATUS_ERR_TOO_MANY_PARAMS
1710 3 SILC_COMMAND_WHOWAS
1713 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1715 Whowas. This command is used to query history information about
1716 specific user. The user maybe requested by their nickname and
1717 server name. The query may find multiple matching users as there
1718 are no unique nicknames in the SILC. The <count> option maybe
1719 given to narrow down the number of accepted results. If this
1720 is not defined there are no limit of accepted results. The query
1721 may also be narrowed down by defining the server name of the
1724 To prevent miss-use of this service wildcards in the nickname
1725 or in the servername are not permitted. The WHOWAS requests must
1726 be based on specific nickname request.
1728 The WHOWAS request must be always forwarded to router by server
1729 so that all users are searched. However, the server still must
1730 search its locally connected clients.
1732 Reply messages to the command:
1735 Arguments: (1) <Status Payload> (2) <nickname>[@<server>]
1738 This command may reply with several command reply messages to form
1739 a list of results. In this case the status payload will include
1740 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1741 the last reply to indicate the end of the list. If there are only
1742 one reply the status is set to normal STATUS_OK.
1744 The command replies with nickname and username and hostname.
1745 Every server must keep history for some period of time of its
1746 locally connected clients.
1751 SILC_STATUS_LIST_START
1752 SILC_STATUS_LIST_END
1753 SILC_STATUS_ERR_NO_SUCH_NICK
1754 SILC_STATUS_ERR_WILDCARDS
1755 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1756 SILC_STATUS_ERR_TOO_MANY_PARAMS
1759 4 SILC_COMMAND_IDENTIFY
1762 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1764 Identify. Identify command is almost analogous to WHOIS command,
1765 except that it does not return as much information. Only relevant
1766 information such as Client ID is returned. This is usually used
1767 to get the Client ID of a client used in the communication with
1770 The query may find multiple matching users as there are no unique
1771 nicknames in the SILC. The <count> option maybe given to narrow
1772 down the number of accepted results. If this is not defined there
1773 are no limit of accepted results. The query may also be narrowed
1774 down by defining the server name of the nickname.
1776 To prevent miss-use of this service wildcards in the nickname
1777 or in the servername are not permitted. It is not allowed
1778 to request all users on some server. The IDENTIFY requests must
1779 be based on specific nickname request.
1781 Implementations may not want to give interface access to this
1782 commands as it is hardly a command that would be used a end user.
1783 However, it must be implemented as it is used with private message
1786 The IDENTIFY must be always forwarded to router by server so that
1787 all users are searched. However, server must still search its
1788 locally connected clients.
1790 Reply messages to the command:
1793 Arguments: (1) <Status Payload> (2) <Client ID>
1794 (3) [<nickname>[@<server>]] (4) [<username@host>]
1796 This command may reply with several command reply messages to form
1797 a list of results. In this case the status payload will include
1798 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1799 the last reply to indicate the end of the list. If there are only
1800 one reply the status is set to normal STATUS_OK.
1802 The command replies with Client ID of the nickname and if more
1803 information is available it may reply with nickname and username
1804 and hostname. If the <count> option were defined in the query
1805 there will be only <count> many replies from the server.
1810 SILC_STATUS_LIST_START
1811 SILC_STATUS_LIST_END
1812 SILC_STATUS_ERR_NO_SUCH_NICK
1813 SILC_STATUS_ERR_WILDCARDS
1814 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1815 SILC_STATUS_ERR_TOO_MANY_PARAMS
1821 Arguments: (1) <nickname>
1823 Set/change nickname. This command is used to set nickname for
1824 user. There is no limit of the length of the nickname in SILC.
1825 Nickname must not include any spaces (` '), non-printable
1826 characters, commas (`,') and any wildcard characters. Note:
1827 nicknames in SILC are case-sensitive which must be taken into
1828 account when searching clients by nickname.
1830 Reply messages to the command:
1833 Arguments: (1) <Status Payload> (2) <New ID Payload>
1835 This command is replied always with New ID Payload that is
1836 generated by the server every time user changes their nickname.
1837 Client receiving this payload must start using the received
1838 Client ID as its current valid Client ID. The New ID Payload
1839 is described in [SILC2].
1844 SILC_STATUS_ERR_WILDCARDS
1845 SILC_STATUS_ERR_NICKNAME_IN_USE
1846 SILC_STATUS_ERR_BAD_NICKNAME
1847 SILC_STATUS_ERR_NOT_REGISTERED
1848 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1849 SILC_STATUS_ERR_TOO_MANY_PARAMS
1855 Arguments: (1) [<Channel ID>] [<server>]
1857 The list command is used to list channels and their topics on
1858 current server. If the <Channel ID> parameter is used, only the
1859 status of that channel is displayed. Secret channels are not
1860 listed at all. Private channels are listed with status indicating
1861 that the channel is private.
1863 If the <server> argument is specified the specified server's
1864 channels are listed. In this case the command must be sent to
1865 the server who owns the channel that was requested.
1867 Reply messages to the command:
1870 Arguments: (1) <Status Payload> (2) <channel>
1873 This command may reply with several command reply messages to form
1874 a list of results. In this case the status payload will include
1875 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1876 the last reply to indicate the end of the list. If there are only
1877 one reply the status is set to normal STATUS_OK.
1879 This command replies with channel name and the topic of the
1880 channel. If the channel is private channel the <topic> includes
1886 SILC_STATUS_LIST_START
1887 SILC_STATUS_LIST_END
1888 SILC_STATUS_ERR_WILDCARDS
1889 SILC_STATUS_ERR_NOT_REGISTERED
1890 SILC_STATUS_ERR_TOO_MANY_PARAMS
1891 SILC_STATUS_ERR_NO_SUCH_CHANNEL
1892 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
1893 SILC_STATUS_ERR_NO_SUCH_SERVER
1896 7 SILC_COMMAND_TOPIC
1899 Arguments: (1) <Channel ID> (2) [<server>]]
1901 This command is used to change or view the topic of a channel.
1902 The topic for channel <Channel ID> is returned if there is no
1903 <topic> given. If the <topic> parameter is present, the topic
1904 for that channel will be changed, if the channel modes permit
1907 Reply messages to the command:
1910 Arguments: (1) <Status Payload> (2) [<topic>]
1912 The command may reply with the topic of the channel if it is
1918 SILC_STATUS_ERR_NOT_ON_CHANNEL
1919 SILC_STATUS_ERR_WILDCARDS
1920 SILC_STATUS_ERR_NOT_REGISTERED
1921 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1922 SILC_STATUS_ERR_NO_SUCH_CHANNEL
1923 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
1924 SILC_STATUS_ERR_NO_CHANNEL_ID
1925 SILC_STATUS_ERR_BAD_CHANNEL_ID
1926 SILC_STATUS_ERR_TOO_MANY_PARAMS
1927 SILC_STATUS_ERR_NO_CHANNEL_PRIV
1930 8 SILC_COMMAND_INVITE
1933 Arguments: (1) <Client ID> (2) <channel>
1935 This command is used to invite other clients to join to the
1936 channel. There is no requirement that the channel the target
1937 client is being invited to must exist or be a valid channel.
1938 The <Client ID> argument is the target client's ID that is being
1941 Reply messages to the command:
1945 Arguments: (1) <Status Payload>
1947 This command replies only with Status Payload.
1952 SILC_STATUS_ERR_NOT_ON_CHANNEL
1953 SILC_STATUS_ERR_WILDCARDS
1954 SILC_STATUS_ERR_NOT_REGISTERED
1955 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1956 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
1957 SILC_STATUS_ERR_TOO_MANY_PARAMS
1958 SILC_STATUS_ERR_NO_RECIPIENT
1959 SILC_STATUS_ERR_USER_ON_CHANNEL
1960 SILC_STATUS_ERR_NO_CLIENT_ID
1966 Arguments: (1) [<quit message>]
1968 This command is used by client to end SILC session. The server
1969 must close the connection to a client which sends this command.
1970 if <quit message> is given it will be sent to other clients on
1971 channel if the client is on channel when quitting.
1973 Reply messages to the command:
1975 This command does not reply anything.
1978 10 SILC_COMMAND_KILL
1981 Arguments: (1) <Client ID> (2) [<comment>]
1983 This command is used by SILC operators to remove a client from
1984 SILC network. The removing has temporary effects and client may
1985 reconnect to SILC network. The <Client ID> is the client to be
1986 removed from SILC. The <comment> argument may be provided to
1987 give to the removed client some information why it was removed
1990 Reply messages to the command:
1993 Arguments: (1) <Status Payload>
1995 This command replies only with Status Payload.
2000 SILC_STATUS_ERR_WILDCARDS
2001 SILC_STATUS_ERR_NOT_REGISTERED
2002 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2003 SILC_STATUS_ERR_TOO_MANY_PARAMS
2004 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2005 SILC_STATUS_ERR_NO_CLIENT_ID
2011 11 SILC_COMMAND_INFO
2014 Arguments: (1) [<server>]
2016 This command is used to fetch various information about a server.
2017 If <server> argument is specified the command must be sent to
2018 the requested server.
2020 Reply messages to the command:
2023 Arguments: (1) <Status Payload> (2) <Server ID>
2026 This command replies with the Server ID of the server and a
2027 string which tells the information about the server.
2032 SILC_STATUS_ERR_WILDCARDS
2033 SILC_STATUS_ERR_NOT_REGISTERED
2034 SILC_STATUS_ERR_TOO_MANY_PARAMS
2035 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2036 SILC_STATUS_ERR_NO_SUCH_SERVER
2039 12 SILC_COMMAND_CONNECT
2042 Arguments: (1) <Server ID>
2043 (2) [<remote server/router>[:<port>]]
2045 This command is used by operators to force a server to try to
2046 establish a new connection to another router (if the connecting
2047 server is normal server) or server (if the conneceting server is
2048 router server). Operator may specify the server/router to be
2049 connected by setting <remote server> argument.
2051 Reply messages to the command:
2054 Arguments: (1) <Status Payload>
2056 This command replies only with Status Payload.
2063 SILC_STATUS_ERR_WILDCARDS
2064 SILC_STATUS_ERR_NOT_REGISTERED
2065 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2066 SILC_STATUS_ERR_TOO_MANY_PARAMS
2067 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2068 SILC_STATUS_ERR_NO_SERVER_PRIV
2069 SILC_STATUS_ERR_NO_ROUTER_PRIV
2072 13 SILC_COMMAND_PING
2075 Arguments: (1) <Server ID>
2077 This command is used by clients to test the communication
2078 channel to its server if client suspects that the communication
2079 is not working correctly. The <Server ID> is the ID of the
2080 server the client is connected to.
2082 Reply messages to the command:
2085 Arguments: (1) <Status Payload>
2087 This command replies only with Status Payload. Server returns
2088 SILC_STATUS_OK in Status Payload if pinging was successful.
2093 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2094 SILC_STATUS_ERR_TOO_MANY_PARAMS
2095 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2096 SILC_STATUS_ERR_NOT_REGISTERED
2099 14 SILC_COMMAND_OPER
2102 Arguments: (1) <username> (2) <authentication data>
2104 This command is used by normal client to obtain server operator
2105 privileges on some server or router. Note that router operator
2106 has router privileges that supersedes the server operator
2107 privileges and this does not obtain those privileges. Client
2108 must use SILCOPER command to obtain router level privileges.
2110 The <username> is the username set in the server configurations
2111 as operator. The <authentication data> is the data that the
2112 client is authenticated against. It may be passphrase prompted
2113 for user on client's screen or it may be public key
2114 authentication data (data signed with private key), or
2117 Reply messages to the command:
2120 Arguments: (1) <Status Payload>
2122 This command replies only with Status Payload.
2127 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2128 SILC_STATUS_ERR_TOO_MANY_PARAMS
2129 SILC_STATUS_ERR_NOT_REGISTERED
2130 SILC_STATUS_ERR_BAD_PASSWORD
2131 SILC_STATUS_ERR_AUTH_FAILED
2134 15 SILC_COMMAND_JOIN
2137 Arguments: (1) <channel> (2) [<passphrase>]
2140 Join to channel/create new channel. This command is used to
2141 join to a channel. If the channel does not exist the channel is
2142 created. If server is normal server this command must be forwarded
2143 to router who will create the channel. The channel may be protected
2144 with passphrase. If this is the case the passphrase must be sent
2145 along the join command.
2147 The name of the <channel> must not include any spaces (` '),
2148 non-printable characters, commas (`,') or any wildcard characters.
2150 Cipher to be used to secure the traffic on the channel may be
2151 requested by sending the name of the requested <cipher>. This
2152 is used only if the channel does not exist and is created. If
2153 the channel already exists the cipher set previously for the
2154 channel will be used to secure the traffic.
2156 The server must check whether the user is allowed to join to
2157 the requested channel. Various modes set to the channel affect
2158 the ability of the user to join the channel. These conditions
2161 o The user must be invited to the channel if the channel
2162 is invite-only channel.
2164 o The Client ID/nickname/username/hostname must not match
2167 o The correct passphrase must be provided if passphrase
2168 is set to the channel.
2170 o The user count limit, if set, must not be reached.
2172 Reply messages to the command:
2175 Arguments: (1) <Status Payload> (2) <channel>
2176 (3) <Channel ID> (4) <channel mode mask>
2179 This command replies with the channel name requested by the
2180 client, channel ID of the channel and topic of the channel
2181 if it exists. It also replies with the channel mode mask
2182 which tells all the modes set on the channel. If the
2183 channel is created the mode mask is zero (0).
2185 Client must not start transmitting to the channel even after
2186 server has replied to this command. Client is permitted to
2187 start transmitting on channel after server has sent packet
2188 SILC_PACKET_CHANNEL_KEY to the client.
2193 SILC_STATUS_ERR_WILDCARDS
2194 SILC_STATUS_ERR_NOT_REGISTERED
2195 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2196 SILC_STATUS_ERR_TOO_MANY_PARAMS
2197 SILC_STATUS_ERR_BAD_PASSWORD
2198 SILC_STATUS_ERR_CHANNEL_IS_FULL
2199 SILC_STATUS_ERR_NOT_INVITED
2200 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
2201 SILC_STATUS_ERR_BAD_CHANNEL
2202 SILC_STATUS_ERR_USER_ON_CHANNEL
2205 16 SILC_COMMAND_MOTD
2208 Arguments: (1) <server>
2210 This command is used to query the Message of the Day of a server.
2212 Reply messages to the command:
2215 Arguments: (1) <Status Payload> (2) [<motd>]
2217 This command replies with the motd message if it exists.
2222 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2223 SILC_STATUS_ERR_TOO_MANY_PARAMS
2224 SILC_STATUS_ERR_NOT_REGISTERED
2225 SILC_STATUS_ERR_NO_SUCH_SERVER
2228 17 SILC_COMMAND_UMODE
2231 Arguments: (1) <Client ID> (2) <client mode mask>
2233 This command is used by client to set/unset modes for itself.
2234 However, there are some modes that the client may not set itself,
2235 but they will be set by server. However, client may unset any
2236 mode. Modes may be masked together ORing them thus having
2237 several modes set. Client must keep its client mode mask
2238 locally so that the mode setting/unsetting would work without
2239 problems. Client may change only its own modes.
2241 Following client modes are defined:
2243 0x0000 SILC_UMODE_NONE
2245 No specific mode for client. This is the initial
2246 setting when new client is created. The client is
2250 0x0001 SILC_UMODE_SERVER_OPERATOR
2252 Marks the user as server operator. Client cannot
2253 set this mode itself. Server sets this mode to the
2254 client when client attains the server operator
2255 privileges by SILC_COMMAND_OPER command. Client
2256 may unset the mode itself.
2259 0x0002 SILC_UMODE_ROUTER_OPERATOR
2261 Marks the user as router (SILC) operator. Client
2262 cannot this mode itself. Router sets this mode to
2263 the client when client attains the router operator
2264 privileges by SILC_COMMAND_SILCOPER command. Client
2265 may unset the mode itself.
2267 Reply messages to the command:
2270 Arguments: (1) <Status Payload> (2) <client mode mask>
2272 This command replies with the changed client mode mask that
2273 the client is required to keep locally.
2279 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2280 SILC_STATUS_ERR_TOO_MANY_PARAMS
2281 SILC_STATUS_ERR_NOT_REGISTERED
2282 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2283 SILC_STATUS_ERR_BAD_CLIENT_ID
2284 SILC_STATUS_ERR_NOT_YOU
2285 SILC_STATUS_ERR_UNKNOWN_MODE
2286 SILC_STATUS_ERR_NO_RECIPIENT
2287 SILC_STATUS_ERR_NO_CLIENT_ID
2290 18 SILC_COMMAND_CMODE
2293 Arguments: (1) <Channel ID> (2) <channel mode mask>
2294 (3) [<user limit>] (4) [<passphrase>]
2295 (5) [<Client ID>] (6) [<cipher>[:<key len>]]
2297 This command is used by client to set or change channel flags on
2298 a channel. Channel has several modes that set various properties
2299 of a channel. Modes may be masked together by ORing them thus
2300 having several modes set. The <Channel ID> is the ID of the
2301 target channel. The client changing channel mode must be on
2302 the same channel and poses sufficient privileges to be able to
2305 Following channel modes are defined:
2307 0x0000 SILC_CMODE_NONE
2309 No specific mode on channel. This is the default when
2310 channel is created. This means that channel is just plain
2314 0x0001 SILC_CMODE_PRIVATE
2316 Channel is private channel. Private channels are shown
2317 in the channel list listed with SILC_COMMAND_LIST command
2318 with indicatioin that the channel is private. Also,
2319 client on private channel will no be detected to be on
2320 the channel as the channel is not shown in the client's
2321 currently joined channel list. Channel founder and
2322 channel operator may set/unset this mode.
2324 Typical implementation would use [+|-]p on user interface
2325 to set/unset this mode.
2328 0x0002 SILC_CMODE_SECRET
2330 Channel is secret channel. Secret channels are not shown
2331 in the list listed with SILC_COMMAND_LIST command. Secret
2332 channels can be considered to be invisible channels.
2333 Channel founder and channel operator may set/unset this
2336 Typical implementation would use [+|-]s on user interface
2337 to set/unset this mode.
2340 0x0004 SILC_CMODE_PRIVKEY
2342 Channel uses private channel key to protect the traffic
2343 on the channel. When this mode is set the client will be
2344 responsible to set the key it wants to use to encrypt and
2345 decrypt the traffic on channel. Server generated channel
2346 keys are not used at all. This mode provides additional
2347 security as clients on channel may agree to use private
2348 channel key that even servers do not know. Naturally,
2349 this requires that every client on the channel knows
2350 the key before hand (it is considered to be pre-shared-
2351 key). This specification does not define how the private
2352 channel key is set as it is entirely local setting on
2355 As it is local setting it is possible to have several
2356 private channel keys on one channel. In this case several
2357 clients can talk on same channel but only those clients
2358 that share the key with the message sender will be able
2359 to hear the talking. Client should not display those
2360 message for the end user that it is not able to decrypt
2361 when this mode is set.
2363 Only channel founder may set/unset this mode. If this
2364 mode is unset the server will distribute new channel
2365 key to all clients on the channel which will be used
2368 Typical implementation would use [+|-]k on user interface
2369 to set/unset this mode.
2372 0x0008 SILC_CMODE_INVITE
2374 Channel is invite only channel. Client may join to this
2375 channel only if it is invited to the channel. Channel
2376 founder and channel operator may set/unset this mode.
2378 Typical implementation would use [+|-]i on user interface
2379 to set/unset this mode.
2382 0x0010 SILC_CMODE_TOPIC
2384 The topic of the channel may only be set by client that
2385 is channel founder or channel operator. Normal clients
2386 on channel will not be able to set topic when this mode
2387 is set. Channel founder and channel operator may set/
2390 Typical implementation would use [+|-]t on user interface
2391 to set/unset this mode.
2394 0x0020 SILC_CMODE_ULIMIT
2396 User limit has been set to the channel. New clients
2397 may not join to the channel when the limit set is
2398 reached. Channel founder and channel operator may set/
2399 unset the limit. The <user limit> argument is the
2400 number of limited users.
2402 Typical implementation would use [+|-]l on user interface
2403 to set/unset this mode.
2406 0x0040 SILC_CMODE_PASSPHRASE
2408 Passphrase has been set to the channel. Client may
2409 join to the channel only if it is able to provide the
2410 correct passphrase. Setting passphrases to channel
2411 is entirely safe as all commands are protected in the
2412 SILC network. Only channel founder may set/unset
2413 the passphrase. The <passphrase> argument is the
2416 Typical implementation would use [+|-]a on user interface
2417 to set/unset this mode.
2420 0x0080 SILC_CMODE_BAN
2422 Ban mask has been set to the channel. The ban mask
2423 may be used to ban specific clients to join the channel.
2424 The <ban mask> argument is the set ban mask. When
2425 unsetting a ban mask the mask must be provided as
2426 argument. Channel founder and channel operator may
2427 set/unset this mode. Channel founder may not be
2428 added to the ban list.
2430 Typical implementation would use [+|-]b on user interface
2431 to set/unset this mode.
2434 0x0100 SILC_CMODE_OPERATOR
2436 Sets channel operator privileges on the channel for a
2437 client on the channel. The <Client ID> argument is the
2438 target client on the channel. Channel founder and
2439 channel operator may set/unset (promote/demote) this
2442 Typical implementation would use [+|-]o on user interface
2443 to set/unset this mode.
2446 0x0200 SILC_CMODE_CIPHER
2448 Sets specific cipher to be used to protect channel
2449 traffic. The <cipher> argument is the requested cipher.
2450 When set or unset the server must re-generate new
2451 channel key. If <key len> argument is specified with
2452 <cipher> argument the new key is generated of <key len>
2455 Typical implementation would use [+|-]c on user interface
2456 to set/unset this mode.
2459 To make the mode system work, client must keep the channel mode
2460 mask locally so that the mode setting and unsetting would work
2461 without problems. The client receives the initial channel mode
2462 mask when it joins to the channel. When the mode changes on
2463 channel the server distributes the changed channel mode mask to
2464 all clients on the channel by sending SILC_COMMAND_CMODE command
2468 Reply messages to the command:
2471 Arguments: (1) <Status Payload> (2) <channel mode mask>
2473 This command replies with the changed channel mode mask that
2474 client is required to keep locally. The same mask is also
2475 sent to all clients on channel by sending additional command
2481 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2482 SILC_STATUS_ERR_TOO_MANY_PARAMS
2483 SILC_STATUS_ERR_NOT_REGISTERED
2484 SILC_STATUS_ERR_NOT_ON_CHANNEL
2485 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2486 SILC_STATUS_ERR_BAD_CHANNEL_ID
2487 SILC_STATUS_ERR_NO_CHANNEL_ID
2488 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2489 SILC_STATUS_ERR_UNKNOWN_MODE
2490 SILC_STATUS_ERR_NO_CLIENT_ID
2495 19 SILC_COMMAND_KICK
2498 Arguments: (1) <channel> (2) <Client ID>
2501 This command is used by channel operators to remove a client from
2502 channel. The <channel> argument is the channel the client to be
2503 removed is on currently. Note that the "kicker" must be on the same
2504 channel. If <comment> is provided it will be sent to the removed
2507 Reply messages to the command:
2510 Arguments: (1) <Status Payload>
2512 This command replies only with Status Payload.
2517 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2518 SILC_STATUS_ERR_TOO_MANY_PARAMS
2519 SILC_STATUS_ERR_NOT_REGISTERED
2520 SILC_STATUS_ERR_NO_SUCH_CHANNEL
2521 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2522 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2523 SILC_STATUS_ERR_NO_CLIENT_ID
2526 20 SILC_COMMAND_RESTART
2531 This command may only be used by server operator to force a
2532 server to restart itself.
2534 Reply messages to the command:
2537 Arguments: (1) <Status Payload>
2539 This command replies only with Status Payload.
2546 SILC_STATUS_ERR_NOT_REGISTERED
2547 SILC_STATUS_ERR_NO_SERVER_PRIV
2550 21 SILC_COMMAND_CLOSE
2553 Arguments: (1) <Server ID>
2555 This command is used only by operator to close connection to a
2556 remote site. The <Server ID> argument is the ID of the remote
2557 site and must be valid.
2559 Reply messages to the command:
2562 Arguments: (1) <Status Payload>
2564 This command replies only with Status Payload.
2571 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2572 SILC_STATUS_ERR_TOO_MANY_PARAMS
2573 SILC_STATUS_ERR_NOT_REGISTERED
2574 SILC_STATUS_ERR_NO_SUCH_SERVER
2575 SILC_STATUS_ERR_NO_SERVER_PRIV
2576 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2584 This command is used only by operator to shutdown the server.
2585 All connections to the server will be closed and the server is
2588 Reply messages to the command:
2593 Arguments: (1) <Status Payload>
2595 This command replies only with Status Payload.
2600 SILC_STATUS_ERR_NOT_REGISTERED
2601 SILC_STATUS_ERR_NO_SERVER_PRIV
2604 23 SILC_COMMAND_SILCOPER
2607 Arguments: (1) <username> (2) <authentication data>
2609 This command is used by normal client to obtain router operator
2610 privileges (also known as SILC operator) on some router. Note
2611 that router operator has router privileges that supersedes the
2612 server operator privileges.
2614 The <username> is the username set in the server configurations
2615 as operator. The <authentication data> is the data that the
2616 client is authenticated against. It may be passphrase prompted
2617 for user on client's screen or it may be public key
2618 authentication data (data signed with private key), or
2621 Difference between router operator and server operator is that
2622 router operator is able to handle cell level properties while
2623 server operator (even on router server) is able to handle only
2624 local properties, such as, local connections and normal server
2627 Reply messages to the command:
2630 Arguments: (1) <Status Payload>
2632 This command replies only with Status Payload.
2637 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2638 SILC_STATUS_ERR_TOO_MANY_PARAMS
2639 SILC_STATUS_ERR_NOT_REGISTERED
2640 SILC_STATUS_ERR_BAD_PASSWORD
2641 SILC_STATUS_ERR_AUTH_FAILED
2644 24 SILC_COMMAND_LEAVE
2647 Arguments: (1) <Channel ID>
2649 This command is used by client to leave a channel the client is
2650 joined to. After a client has leaved the channel the server
2651 must create new key for the channel and distribute to all clients
2652 still currently on the channel.
2654 Reply messages to the command:
2657 Arguments: (1) <Status Payload>
2659 This command replies only with Status Payload.
2664 SILC_STATUS_ERR_NOT_REGISTERED
2665 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2666 SILC_STATUS_ERR_TOO_MANY_PARAMS
2667 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2668 SILC_STATUS_ERR_BAD_CHANNEL_ID
2669 SILC_STATUS_ERR_NO_CHANNEL_ID
2672 25 SILC_COMMAND_NAMES
2675 Arguments: (1) <Channel ID>
2677 This command is used to list user names currently on the requested
2678 channel; argument <Channel ID>. The server must resolve the
2679 user names and send a comma (`,') separated list of user names
2680 on the channel. Server or router may resolve the names by sending
2681 SILC_COMMAND_WHOIS commands.
2683 If the requested channel is a private or secret channel, this
2684 command must not send the list of users, as private and secret
2685 channels cannot be seen by outside. In this case the returned
2686 name list may include a indication that the server could not
2687 resolve the names of the users on the channel.
2689 Reply messages to the command:
2692 Arguments: (1) <Status Payload> (2) <name list>
2694 This command replies with the comma separated list of users on
2700 SILC_STATUS_ERR_NOT_REGISTERED
2701 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2702 SILC_STATUS_ERR_TOO_MANY_PARAMS
2703 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2704 SILC_STATUS_ERR_BAD_CHANNEL_ID
2705 SILC_STATUS_ERR_NO_CHANNEL_ID
2706 SILC_STATUS_ERR_NOT_ON_CHANNEL
2711 Currently undefined commands.
2714 255 SILC_COMMAND_MAX
2716 Reserved command. This must not be sent.
2721 5.3 SILC Command Status Types
2724 5.3.1 SILC Command Status Payload
2726 Command Status Payload is sent in command reply messages to indicate
2727 the status of the command. The payload is one of argument in the
2728 command thus this is the data area in Command Argument Payload described
2729 in [SILC2]. The payload is only 2 bytes of length. Following diagram
2730 represents the Command Status Payload (field is always in MSB order).
2736 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
2737 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2739 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2743 Figure 5: SILC Command Status Payload
2747 o Status Message (2 bytes) - Indicates the status message.
2748 All Status messages are described in the next section.
2753 5.3.2 SILC Command Status List
2755 Command Status messages are returned in the command reply messages
2756 to indicate whether the command were executed without errors. If error
2757 has occured the status tells which error occured. Status payload only
2758 sends numeric reply about the status. Receiver of the payload must
2759 convert the numeric values into human readable error messages. The
2760 list of status messages below has an example human readable error
2761 messages that client may display for the user.
2763 List of all defined command status messages following.
2766 Generic status messages:
2770 Ok status. Everything went Ok. The status payload maybe
2771 safely ignored in this case.
2773 1 SILC_STATUS_LIST_START
2775 Start of the list. There will be several command replies and
2776 this reply is the start of the list.
2778 2 SILC_STATUS_LIST_END
2780 End of the list. There were several command replies and this
2781 reply is the last of the list. There won't be other replies
2782 beloning to this list after this one.
2786 Currently undefined and has been reserved for the future.
2789 Error status message:
2791 10 SILC_STATUS_ERR_NO_SUCH_NICK
2793 "No such nickname". Requested nickname does not exist.
2795 11 SILC_STATUS_ERR_NO_SUCH_CHANNEL
2797 "No such channel". Requested channel name does not exist.
2799 12 SILC_STATUS_ERR_NO_SUCH_SERVER
2801 "No such server". Requested server name does not exist.
2803 13 SILC_STATUS_ERR_TOO_MANY_TARGETS
2805 "Duplicate recipients. No message delivered". Message were
2806 tried to be sent to recipient which has several occurrences in
2809 14 SILC_STATUS_ERR_NO_RECIPIENT
2811 "No recipient given". Command required recipient which was
2814 15 SILC_STATUS_ERR_UNKNOWN_COMMAND
2816 "Unknown command". Command sent to server is unknown by the
2819 16 SILC_STATUS_ERR_WILDCARDS
2821 "Wildcards cannot be used". Wildcards were provided but they
2824 17 SILC_STATUS_ERR_NO_CLIENT_ID
2826 "No Client ID given". Client ID were expected as command
2827 parameter but were not found.
2829 18 SILC_STATUS_ERR_NO_CHANNEL_ID
2831 "No Channel ID given". Channel ID were expected as command
2832 parameter but were not found.
2834 19 SILC_STATUS_ERR_BAD_CLIENT_ID
2836 "Bad Client ID". Client ID provided were erroneous.
2838 20 SILC_STATUS_ERR_BAD_CHANNEL_ID
2840 "Bad Channel ID". Channel ID provided were erroneous.
2842 21 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2844 "No such Client ID". Client ID provided does not exist.
2847 22 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2849 "No such Channel ID". Channel ID provided does not exist.
2851 23 SILC_STATUS_ERR_NICKNAME_IN_USE
2853 "Nickname already exists". Nickname created could not be
2854 registered because number of same nicknames were already set to
2855 maximum. This is not expected to happen in real life but is
2858 24 SILC_STATUS_ERR_NOT_ON_CHANNEL
2860 "You are not on that channel". The command were specified for
2861 client user is not currently on.
2863 25 SILC_STATUS_ERR_USER_ON_CHANNEL
2865 "User already on channel". User were invited on channel they
2868 26 SILC_STATUS_ERR_NOT_REGISTERED
2870 "You have not registered". User executed command that requires
2871 the client to be registered on the server before it may be
2874 27 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2876 "Not enough parameters". Command requires more parameters
2879 28 SILC_STATUS_ERR_TOO_MANY_PARAMS
2881 "Too many parameters". Too many parameters were provided
2884 29 SILC_STATUS_ERR_PERM_DENIED
2886 "Your host is not among the privileged". The client tried to
2887 register on server that does not allow this host to connect.
2889 30 SILC_STATUS_ERR_BANNED_FROM_SERVER
2891 "You are banned from this server". The client tried to register
2892 on server that has explicitly denied this host to connect.
2896 31 SILC_STATUS_ERR_BAD_PASSWORD
2898 "Cannot join channel. Incorrect password". Password provided for
2899 channel were not accepted.
2901 32 SILC_STATUS_ERR_CHANNEL_IS_FULL
2903 "Cannot join channel. Channel is full". The channel is full
2904 and client cannot be joined to it.
2906 33 SILC_STATUS_ERR_NOT_INVITED
2908 "Cannot join channel. You have not been invited". The channel
2909 is invite only channel and client has not been invited.
2911 34 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
2913 "Cannot join channel. You have been banned". The client has
2914 been banned from the channel.
2916 35 SILC_STATUS_ERR_UNKNOWN_MODE
2918 "Unknown mode". Mode provided by the client were unknown to
2921 36 SILC_STATUS_ERR_NOT_YOU
2923 "Cannot change mode for other users". User tried to change
2924 someone else's mode.
2926 37 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2928 "Permission denied. You are not channel operator". Command may
2929 be executed only by channel operator.
2931 38 SILC_STATUS_ERR_NO_SERVER_PRIV
2933 "Permission denied. You are not server operator". Command may
2934 be executed only by server operator.
2936 39 SILC_STATUS_ERR_NO_ROUTER_PRIV
2938 "Permission denied. You are not SILC operator". Command may be
2939 executed only by router (SILC) operator.
2941 40 SILC_STATUS_ERR_BAD_NICKNAME
2943 "Bad nickname". Nickname requested contained illegal characters
2946 41 SILC_STATUS_ERR_BAD_CHANNEL
2948 "Bad channel name". Channel requested contained illegal characters
2951 42 SILC_STATUS_ERR_AUTH_FAILED
2953 "Authentication failed". The authentication data sent as
2954 argument were wrong and thus authentication failed.
2959 6 Security Considerations
2961 Security is central to the design of this protocol, and these security
2962 considerations permeate the specification.
2971 [SILC2] Riikonen, P., "SILC Packet Protocol", Internet Draft,
2974 [SILC3] Riikonen, P., "SILC Key Exchange and Authentication
2975 Protocols", Internet Draft, June 2000.
2977 [IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
2980 [SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
2983 [PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
2986 [SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
2989 [PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
2990 Infrastructure, Certificate and CRL Profile", RFC 2459,
2993 [Schneier] Schneier, B., "Applied Cryptography Second Edition",
2994 John Wiley & Sons, New York, NY, 1996.
2996 [Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
2999 [OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
3000 RFC 2412, November 1998.
3002 [ISAKMP] Maughan D., et al, "Internet Security Association and
3003 Key Management Protocol (ISAKMP)", RFC 2408, November
3006 [IKE] Harkins D., and Carrel D., "The Internet Key Exhange
3007 (IKE)", RFC 2409, November 1998.
3009 [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
3010 Authentication", RFC 2104, February 1997.
3023 EMail: priikone@poseidon.pspt.fi
3025 This Internet-Draft expires 28 Jan 2001