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 Following ports has been assigned by IANA for the SILC protocol:
555 If there are needs to create new SILC networks in the future the port
556 numbers must be officially assigned by the IANA.
558 Server on network above privileged ports (>1023) should not be trusted
559 as they could have been set up by untrusted party.
565 Router server in SILC network is responsible for keeping the cell together
566 and routing messages to other servers and to other routers. Router server
567 is also a normal server thus clients may connect to it as it would be
568 just normal SILC server.
570 However, router servers has a lot of important tasks that normal servers
571 do not have. Router server knows everything about everything in the SILC.
572 They know all clients currently on SILC, all servers and routers and all
573 channels in SILC. Routers are the only servers in SILC that care about
574 global information and keeping them up to date at all time. And, this
575 is what they must do.
579 3.3.1 Router's Local ID List
581 Router server as well must keep local list of connected clients and
582 locally created channels. However, this list is extended to include all
583 the informations of the entire cell, not just the server itself as for
586 However, on router this list is a lot smaller since routers do not keep
587 information about user's nickname, username and hostname and real name
588 since these are not needed by the router. Router keeps only information
595 Hence, local list for router includes:
598 server list - All servers in the cell
605 client list - All clients in the cell
608 channel list - All channels in the cell
610 o Client ID's on channel
611 o Client ID modes on channel
616 Note that locally connected clients and other information include all the
617 same information as defined in section section 3.2.1 Server's Local ID
622 3.3.2 Router's Global ID List
624 Router server must also keep global list. Normal servers do not have
625 global list as they know only about local information. Global list
626 includes all the clients on SILC, their Client ID's, all created channels
627 and their Channel ID's and all servers and routers on SILC and their
628 Server ID's. That is said, global list is for global information and the
629 list must not include the local information already on the router's local
632 Note that the global list does not include information like nicknames,
633 usernames and hostnames or user's real names. Router does not keep
634 these informations as they are not needed by the router. This
635 information is available from the client's server which maybe queried
638 Hence, global list includes:
641 server list - All servers in SILC
647 client list - All clients in SILC
650 channel list - All channels in SILC
652 o Client ID's on channel
653 o Client ID modes on channel
658 3.3.3 Router's Server ID
660 Router's Server ID's are equivalent to normal Server ID's. As routers
661 are normal servers as well same types of ID's applies for routers as well.
662 Thus, see section 3.2.2 Server ID. Server ID's for routers are always
663 created by the remote router where the router is connected to.
669 A channel is a named group of one or more clients which will all receive
670 messages addressed to that channel. The channel is created when first
671 client requests JOIN command to the channel, and the channel ceases to
672 exist when the last client leaves it. When channel exists, any client
673 can reference it using the name of the channel.
675 Channel names are unique although the real uniqueness comes from 64 bit
676 Channel ID that unifies each channel. However, channel names are still
677 unique and no two global channels with same name may exist. Channel name
678 is a string which begins with `#' character. There is no limit on the
679 length of the channel name. Channel names may not contain any spaces
680 (` '), any non-printable ASCII characters, commas (`,') and wildcard
683 Channels can have operators that can administrate the channel and
684 operate all of its modes. Following operators on channel exist on SILC
688 o Channel founder - When channel is created the joining client becomes
689 channel founder. Channel founder is channel operator with some more
690 privileges. Basically, channel founder can fully operate the channel
691 and all of its modes. The privileges are limited only to the particular
692 channel. There can be only one channel founder per channel. Channel
693 founder supersedes channel operator's privileges.
695 Channel founder privileges cannot be removed by any other operator on
696 channel. When channel founder leaves the channel there is no channel
697 founder on the channel. Channel founder also cannot be removed by
698 force from the channel.
700 o Channel operator - When client joins to channel that has not existed
701 previously it will become automatically channel operator (and channel
702 founder discussed above). Channel operator is able administrate the
703 channel, set some modes on channel, remove a badly behaving client from
704 the channel and promote other clients to become channel operator.
705 The privileges are limited only to the particular channel.
707 Normal channel user may be promoted (opped) to channel operator
708 gaining channel operator privileges. Channel founder or other channel
709 operator may also demote (deop) channel operator to normal channel
717 Channels are distinguished from other channels by unique Channel ID.
718 The Channel ID is a 64 bit ID and collisions are not expected to happen
719 in any conditions. Channel names are just for logical use of channels.
720 The Channel ID is created by the server where the channel is created.
721 The Channel ID is defined as follows.
724 64 bit Channel ID based on IPv4 addresses:
726 32 bit Router's Server ID IP address (bits 1-32)
727 16 bit Router's Server ID port (bits 33-48)
730 o Router's Server ID IP address - Indicates the IP address of
731 the router of the cell where this channel is created. This is
732 taken from the router's Server ID. This way SILC router knows
733 where this channel resides in the SILC network.
735 o Router's Server ID port - Indicates the port of the channel on
736 the server. This is taken from the router's Server ID.
738 o Random number - To further unify the Channel ID. This makes
739 sure that there are no collisions. This also means that
740 in a cell there can be 2^16 channels.
747 Operators are normal users with extra privileges to their server or
748 router. Usually these people are SILC server and router administrators
749 that take care of their own server and clients on them. The purpose of
750 operators is to administrate the SILC server or router. However, even
751 an operator with highest privileges is not able to enter invite-only
752 channel, to gain access to the contents of a encrypted and authenticated
753 packets traveling in the SILC network or to gain channel operator
754 privileges on public channels without being promoted. They have the
755 same privileges as everyone else except they are able to administrate
756 their server or router.
762 Commands are very important part on SILC network especially for client
763 which uses commands to operate on the SILC network. Commands are used
764 to set nickname, join to channel, change modes and many other things.
766 Client usually sends the commands and server replies by sending a reply
767 packet to the command. Server may also send commands usually to serve
768 the original client's request. However, server may not send command
769 to client and there are some commands that server must not send. Server
770 is also able to send the forwarded command packets. For example,
771 SILC_COMMAND_JOIN is always forwarded packet. See [SILC2] for more
772 about packet forwarding.
774 Note that the command reply is usually sent only after client has sent
775 the command request but server is allowed to send command reply packet
776 to client even if client has not requested the command. Client may,
777 however, choose not to accept the command reply, but there are some
778 command replies that the client should accept. Example of a such
779 command reply is reply to SILC_COMMAND_CMODE command that the server
780 uses to distribute the channel mode on all clients on the channel
781 when the mode has changed.
783 It is expected that some of the commands may be miss-used by clients
784 resulting various problems on the server side. Every implementation
785 should assure that commands may not be executed more than once, say,
786 in two (2) seconds. This should be sufficient to prevent the miss-use
789 SILC commands are described in section 5 SILC Commands.
795 Packets are naturally the most important part of the protocol and the
796 packets are what actually makes the protocol. Packets in SILC network
797 are always encrypted using, usually, the shared secret session key
798 or some other key, for example, channel key, when encrypting channel
799 messages. The SILC Packet Protocol is a wide protocol and is described
800 in [SILC2]. This document does not define or describe details of
807 3.8 Packet Encryption
809 All packets passed in SILC network must be encrypted. This section
810 defines how packets must be encrypted in the SILC network. The detailed
811 description of the actual encryption process of the packets are
812 described in [SILC2].
814 Client and its server shares secret symmetric session key which is
815 established by the SILC Key Exchange Protocol, described in [SILC3].
816 Every packet sent from client to server, with exception of packets for
817 channels, are encrypted with this session key.
819 Channels has their own key that are shared by every client on the channel.
820 However, the channel keys are cell specific thus one cell does not know
821 the channel key of the other cell, even if that key is for same channel.
822 Channel key is also known by the routers and all servers that has clients
823 on the channel. However, channels may have channel private keys that
824 are entirely local setting for client. All clients on the channel must
825 know the channel private key before hand to be able to talk on the
826 channel. In this case, no server or router knows the key for channel.
828 Server shares secret symmetric session key with router which is
829 established by the SILC Key Exchange Protocol. Every packet passed from
830 server to router, with exception of packets for channels, are encrypted
831 with the shared session key. Same way, router server shares secret
832 symmetric key with its primary route. However, every packet passed
833 from router to other router, including packets for channels, are
834 encrypted with the shared session key. Every router connection has
835 their own session keys.
839 3.8.1 Determination of the Source and the Destination
841 The source and the destination of the packet needs to be determined
842 to be able to route the packets to correct receiver. This information
843 is available in the SILC Packet Header which is included in all packets
844 sent in SILC network. The SILC Packet Header is described in [SILC2].
846 The header is always encrypted with the session key who is next receiver
847 of the packet along the route. The receiver of the packet, for example
848 a router along the route, is able to determine the sender and the
849 destination of the packet by decrypting the SILC Packet Header and
850 checking the ID's attached to the header. The ID's in the header will
851 tell to where the packet needs to be sent and where it is coming from.
853 The header in the packet does not change during the routing of the
854 packet. The original sender, for example client, assembles the packet
855 and the packet header and server or router between the sender and the
856 receiver must not change the packet header.
858 Note that the packet and the packet header may be encrypted with
859 different keys. For example, packets to channels are encrypted with
860 the channel key, however, the header is encrypted with the session key
861 as described above. However, the header and the packet may be encrypted
862 with same key. This is case, for example, with command packets.
866 3.8.2 Client To Client
868 Process of message delivery and encryption from client to another
869 client is as follows.
871 Example: Private message from client to another client on different
872 servers. Clients do not share private message delivery
873 keys; normal session keys are used.
875 o Client 1. sends encrypted packet to its server. The packet is
876 encrypted with the session key shared between client and its
879 o Server determines the destination of the packet and decrypts
880 the packet. Server encrypts the packet with session key shared
881 between the server and its router, and sends the packet to the
884 o Router determines the destination of the packet and decrypts
885 the packet. Router encrypts the packet with session key
886 shared between the router and the destination server, and sends
887 the packet to the server.
889 o Server determines the client to which the packet is destined
890 to and decrypts the packet. Server encrypts the packet with
891 session key shared between the server and the destination client,
892 and sends the packet to the client.
894 o Client 2. decrypts the packet.
897 Example: Private message from client to another client on different
898 servers. Clients has established secret shared private
899 message delivery key with each other and that is used in
900 the message encryption.
902 o Client 1. sends encrypted packet to its server. The packet is
903 encrypted with the private message delivery key shared between
906 o Server determines the destination of the packet and sends the
907 packet to the router.
909 o Router determines the destination of the packet and sends the
910 packet to the server.
912 o Server determines the client to which the packet is destined
913 to and sends the packet to the client.
915 o Client 2. decrypts the packet with the secret shared key.
918 If clients share secret key with each other the private message
919 delivery is much simpler since servers and routers between the
920 clients do not need to decrypt and re-encrypt the packet.
922 The process for clients on same server is much simpler as there are
923 no need to send the packet to the router. The process for clients
924 on different cells is same as above except that the packet is routed
925 outside the cell. The router of the destination cell routes the
926 packet to the destination same way as described above.
930 3.8.3 Client To Channel
932 Process of message delivery from client on channel to all the clients
935 Example: Channel of four users; two on same server, other two on
936 different cells. Client sends message to the channel.
938 o Client 1. encrypts the packet with channel key and sends the
939 packet to its server.
941 o Server determines local clients on the channel and sends the
942 packet to the Client on the same server. Server then sends
943 the packet to its router for further routing.
945 o Router determines local clients on the channel, if found
946 sends packet to the local clients. Router determines global
947 clients on the channel and sends the packet to its primary
948 router or fastest route.
950 o (Other router(s) do the same thing and sends the packet to
953 o Server determines local clients on the channel and sends the
954 packet to the client.
956 o All clients receiving the packet decrypts the packet.
960 3.8.4 Server To Server
962 Server to server packet delivery and encryption is described in above
963 examples. Router to router packet delivery is analogous to server to
964 server. However, some packets, such as channel packets, are processed
965 differently. These cases are described later in this document and
966 more in detail in [SILC2].
970 3.9 Key Exchange And Authentication
972 Key exchange is done always when for example client connects to server
973 but also when server and router and router and router connects to each
974 other. The purpose of key exchange protocol is to provide secure key
975 material to be used in the communication. The key material is used to
976 derive various security parameters used to secure SILC packets. The
977 SILC Key Exchange protocol is described in detail in [SILC3].
979 Authentication is done after key exchange protocol has been successfully
980 completed. The purpose of authentication is to authenticate for example
981 client connecting to the server. However, Usually clients are accepted
982 to connect to server without explicit authentication. Servers are
983 required use authentication protocol when connecting. The authentication
984 may be based on passphrase (pre-shared-secret) or public key. The
985 connection authentication protocol is described in detail in [SILC3].
991 This section defines all the allowed algorithms that can be used in
992 the SILC protocol. This includes mandatory cipher, mandatory public
993 key algorithm and MAC algorithms.
999 Cipher is the encryption algorithm that is used to protect the data
1000 in the SILC packets. See [SILC2] of the actual encryption process and
1001 definition of how it must be done. SILC has a mandatory algorithm that
1002 must be supported in order to be compliant with this protocol.
1009 Following ciphers are defined in SILC protocol:
1012 blowfish-cbc Blowfish in CBC mode (mandatory)
1013 twofish-cbc Twofish in CBC mode (optional)
1014 rc6-cbc RC6 in CBC mode (optional)
1015 rc5-cbc RC5 in CBC mode (optional)
1016 mars-cbc Mars in CBC mode (optional)
1017 none No encryption (optional)
1021 All algorithms must use minimum of 128 bit key, by default. Several
1022 algorithms, however, supports longer keys and it is recommended to use
1023 longer keys if they are available.
1025 Algorithm none does not perform any encryption process at all and
1026 thus is not recommended to be used. It is recommended that no client
1027 or server implementation would accept none algorithms except in special
1030 Additional ciphers may be defined to be used in SILC by using the
1031 same name format as above.
1035 3.10.2 Public Key Algorithms
1037 Public keys are used in SILC to authenticate entities in SILC network
1038 and to perform other tasks related to public key cryptography. The
1039 public keys are also used in the SILC Key Exchange protocol [SILC3].
1041 Following public key algorithms are defined in SILC protocol:
1048 Both of the algorithms are described in [Scheneir] and [Menezes].
1050 Additional public key algorithms may be defined to be used in SILC.
1054 3.10.3 MAC Algorithms
1056 Data integrity is protected by computing a message authentication code
1057 (MAC) of the packet data. See [SILC2] for details how to compute the
1064 Following MAC algorithms are defined in SILC protocol:
1067 hmac-sha1 HMAC-SHA1, length = 20 (mandatory)
1068 hmac-md5 HMAC-MD5, length = 16 (optional)
1069 none No MAC (optional)
1072 The none MAC is not recommended to be used as the packet is not
1073 authenticated when MAC is not computed. It is recommended that no
1074 client or server would accept none MAC except in special debugging
1077 The HMAC algorithm is described in [HMAC] and hash algorithms that
1078 are used as part of the HMACs are described in [Scheneir] and in
1081 Additional MAC algorithms may be defined to be used in SILC.
1085 3.10.4 Compression Algorithms
1087 SILC protocol supports compression that may be applied to unencrypted
1088 data. It is recommended to use compression on slow links as it may
1089 significantly speed up the data transmission. By default, SILC does not
1090 use compression which is the mode that must be supported by all SILC
1093 Following compression algorithms are defined:
1096 none No compression (mandatory)
1097 zlib GBU ZLIB (LZ77) compression (optional)
1100 Additional compression algorithms may be defined to be used in SILC.
1104 3.11 SILC Public Key
1106 This section defines the type and format of the SILC public key. All
1107 implementations must support this public key type. See [SILC3] for
1108 other optional public key and certificate types allowed in SILC
1109 protocol. Public keys in SILC may be used to authenticate entities
1110 and to perform other tasks related to public key cryptography.
1112 The format of the SILC Public Key is as follows:
1123 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
1124 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1125 | Public Key Length |
1126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1127 | Algorithm Name Length | |
1128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1133 | Identifier Length | |
1134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1138 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1146 Figure 4: SILC Public Key
1150 o Public Key Length (4 bytes) - Indicates the full length
1151 of the public key, not including this field.
1153 o Algorithm Name Length (2 bytes) - Indicates the length
1154 of the Algorithm Length field, not including this field.
1156 o Algorithm name (variable length) - Indicates the name
1157 of the public key algorithm that the key is. See the
1158 section 3.10.2 Public Key Algorithms for defined names.
1160 o Identifier Length (2 bytes) - Indicates the length of
1161 the Identifier field, not including this field.
1163 o Identifier (variable length) - Indicates the identifier
1164 of the public key. This data can be used to identify
1165 the owner of the key. The identifier is of following
1169 HN Host name or IP address
1176 Examples of an identifier:
1178 `UN=priikone, HN=poseidon.pspt.fi, E=priikone@poseidon.pspt.fi'
1180 `UN=sam, HN=dummy.fi, RN=Sammy Sam, O=Company XYZ, C=Finland'
1182 At least user name (UN) and host name (HN) must be provided as
1183 identifier. The fields are separated by commas (`,'). If
1184 comma is in the identifier string it must be written as `\\,',
1185 for example, `O=Company XYZ\\, Inc.'.
1187 o Public Data (variable length) - Includes the actual
1188 public data of the public key.
1190 The format of this field for RSA algorithm is
1199 The format of this field for DSS algorithm is
1211 The variable length fields are multiple precession
1212 integers encoded as strings in both examples.
1214 Other algorithms must define their own type of this
1215 field if they are used.
1218 All fields in the public key are in MSB (most significant byte first)
1225 This section describes various SILC procedures such as how the
1226 connections are created and registered, how channels are created and
1227 so on. The section describes the procedures only generally as details
1228 are described in [SILC2] and [SILC3].
1232 4.1 Creating Client Connection
1234 This section descibres the procedure when client connects to SILC server.
1235 When client connects to server the server must perform IP address lookup
1236 and reverse IP address lookup to assure that the origin host really is
1237 who it claims to be. Client, host, connecting to server must have
1238 both valid IP address and fully qualified domain name (FQDN).
1240 After that client and server performs SILC Key Exchange protocol which
1241 will provide the key material used later in the communication. The
1242 key exchange protocol must be completed successfully before the connection
1243 registration may continue. The SILC Key Exchange protocol is described
1246 Typical server implementation would keep a list of connections that it
1247 allows to connect to the server. The implementation would check, for
1248 example, the connecting client's IP address from the connection list
1249 before the SILC Key Exchange protocol has been started. Reason for
1250 this is that if the host is not allowed to connect to the server there
1251 is no reason to perform a key exchange protocol.
1253 After successful key exchange protocol the client and server performs
1254 connection authentication protocol. The purpose of the protocol is to
1255 authenticate the client connecting to the server. Flexible
1256 implementation could also accept the client to connect to the server
1257 without explicit authentication. However, if authentication is
1258 desired for a specific client it may be based on passphrase or
1259 public key authentication. If authentication fails the connection
1260 must be terminated. The connection authentication protocol is described
1263 After successful key exchange and authentication protocol the client
1264 registers itself by sending SILC_PACKET_NEW_CLIENT packet to the
1265 server. This packet includes various information about the client
1266 that the server uses to create the client. Server creates the client
1267 and sends SILC_PACKET_NEW_ID to the client which includes the created
1268 Client ID that the client must start using after that. After that
1269 all SILC packets from the client must have the Client ID as the
1270 Source ID in the SILC Packet Header, described in [SILC2].
1272 Client must also get the server's Server ID that is to be used as
1273 Destination ID in the SILC Packet Header when communicating with
1274 the server (for example when sending commands to the server). The
1275 ID may be resolved in two ways. Client can take the ID from an
1276 previously received packet from server that must include the ID,
1277 or to send SILC_COMMAND_INFO command and receive the Server ID as
1280 Server may choose not to use the information received in the
1281 SILC_PACKET_NEW_CLIENT packet. For example, if public key or
1282 certificate were used in the authentication, server may use those
1283 informations rather than what it received from client. This is suitable
1284 way to get the true information about client if it is available.
1286 The nickname of client is initially set to the username sent in the
1287 SILC_PACKET_NEW_CLIENT packet. User should set the nickname to more
1288 suitable by sending SILC_COMMAND_NICK command. However, this is not
1289 required as part of registration process.
1291 Server must also distribute the information about newly registered
1292 client to its router (or if the server is router, to all routers in
1293 the SILC network). More information about this in [SILC2].
1297 4.2 Creating Server Connection
1299 This section descibres the procedure when server connects to its
1300 router (or when router connects to other router, the cases are
1301 equivalent). The procedure is very much alike when client connects
1302 to the server thus it is not repeated here.
1304 One difference is that server must perform connection authentication
1305 protocol with proper authentication. Proper authentication is based
1306 on passphrase or public key authentication.
1308 After server and router has successfully performed the key exchange
1309 and connection authentication protocol, the server register itself
1310 to the router by sending SILC_PACKET_NEW_SERVER packet. This packet
1311 includes the server's Server ID that it has created by itself and
1312 other relevant information about the server.
1314 After router has received the SILC_PACKET_NEW_SERVER packet it
1315 distributes the information about newly registered server to all routers
1316 in the SILC network. More information about this in [SILC2].
1318 As client needed to resolve the destination ID this must be done by the
1319 server that connected to the router, as well. The way to resolve it is
1320 to get the ID from previously received packet. Server must also start
1321 using its own Server ID as Source ID in SILC Packet Header and the
1322 router's Server ID as Destination when communicating with the router.
1324 If the server has already connected clients and locally created
1325 channels the server must distribute these informations to the router.
1326 The distribution is done by sending packet SILC_PACKET_NEW_CHANNEL.
1327 See [SILC2] for more information on this.
1331 4.3 Joining to a Channel
1333 This section describes the procedure when client joins to a channel.
1334 Client may join to channel by sending command SILC_COMMAND_JOIN to the
1335 server. If the receiver receiving join command is normal server the
1336 server must check its local list whether this channel already exists
1337 locally. This would indicate that some client connected to the server
1338 has already joined to the channel. If this is case the client is
1339 joined to the client, new channel key is created and information about
1340 newly joined channel is sent to the router. The new channel key is
1341 also distributed to the router and to all clients on the channel.
1343 If the channel does not exist in the local list the command must be
1344 fowarded to the router which will then perform the actual joining
1345 procedure. When server receives the reply to the command from the
1346 router it must be distributed to the client who sent the command
1347 originally. Server will also receive the channel key from the server
1348 that it must distribute to the client who originally requested the
1349 join command. The server must also save the channel key.
1351 If the receiver of the join command is router it must first check its
1352 local list whether anyone in the cell has already joined to the channel.
1353 If this is the case the client is joined to the channel and reply is
1354 sent to the client. If the command was sent by server the command reply
1355 is sent to the server who sent it. Then the router must also create
1356 new channel key and distribute it to all clients on the channel and
1357 all servers that has clients on the channel.
1359 If the channel does not exist on the router's local list it must
1360 check the global list whether the channel exists at all. If it does
1361 the client is joined to the channel as described previously. If
1362 the channel does not exist the channel is created and the client
1363 is joined to the channel. The channel key is also created and
1364 distributed as previously described. The client joining to the created
1365 channel is made automatically channel founder and both channel founder
1366 and channel operator privileges is set for the client.
1368 When the router joins the client to the channel it must send
1369 information about newly joined client to all routers in the SILC
1370 network. Also, if the channel was created in the process, information
1371 about newly created channel must also be distributed to all routers.
1372 The distribution of newly created channel is done by sending packet
1373 SILC_PACKET_NEW_CHANNEL.
1375 It is important to note that new channel key is created always when
1376 new client joins to channel, whether the channel has existed previously
1377 or not. This way the new client on the channel is not able to decrypt
1378 any of the old traffic on the channel.
1380 Client who receives the reply to the join command must start using
1381 the received Channel ID in the channel message communication thereafter.
1382 However, client must not start communicating on the channel before
1383 it has received the packet SILC_PACKET_CHANNEL_KEY.
1385 If client wants to know the other clients currently on the channel
1386 the client must send SILC_COMMAND_NAMES command to receive a list of
1387 channel users. Server implementation, however, may send command reply
1388 packet to SILC_COMMAND_NAMES command after client has joined to the
1389 channel even if the client has not sent the command.
1393 4.4 Channel Key Generation
1395 Channel keys are created by router who creates the channel by taking
1396 enough randomness from cryptographically strong random number generator.
1397 The key is generated always when channel is created, when new client
1398 joins a channel and after the key has expired. Key could expire for
1401 The key must also be re-generated whenever some client leaves a channel.
1402 In this case the key is created from scratch by taking enough randomness
1403 from the random number generator. After that the key is distributed to
1404 all clients on the channel. However, channel keys are cell specific thus
1405 the key is created only on the cell where the client, who leaved the
1406 channel, exists. While the server or router is creating the new channel
1407 key, no other client may join to the channel. Messages that are sent
1408 while creating the new key are still processed with the old key. After
1409 server has sent the SILC_PACKET_CHANNEL_KEY packet must client start
1410 using the new key. If server creates the new key the server must also
1411 send the new key to its router. See [SILC2] on more information about
1412 how channel messages must be encrypted and decrypted when router is
1417 4.5 Private Message Sending and Reception
1419 Private messages are sent point to point. Client explicitly destines
1420 a private message to specific client that is delivered to only to that
1421 client. No other client may receive the private message. The receiver
1422 of the private message is destined in the SILC Packet Header as any
1423 other packet as well.
1425 If the sender of a private message does not know the receiver's Client
1426 ID, it must resolve it from server. There are two ways to resolve the
1427 client ID from server; it is recommended that client ipmlementations
1428 send SILC_COMMAND_IDENTIFY command to receive the Client ID. Client
1429 may also send SILC_COMMAND_WHOIS command to receive the Client ID.
1430 If the sender has received earlier a private message from the receiver
1431 it should have cached the Client ID from the SILC Packet Header.
1433 Receiver of a private message should not explicitly trust the nickname
1434 that it receives in the Private Message Payload, described in [SILC2].
1435 Implementations could resolve the nickname from server, as described
1436 previously, and compare the received Client ID and the SILC Packet
1437 Header's Client ID. The nickname in the payload is merely provided
1438 to be displayed for end user.
1440 See [SILC2] for describtion of private message encryption and decryption
1445 4.6 Private Message Key Generation
1447 Private message may be protected by key generated by client. The key
1448 may be generated and sent to the other client by sending packet
1449 SILC_PACKET_PRIVATE_MESSAGE_KEY which travels through the network
1450 and is secured by session keys. After that the private message key
1451 is used in the private message communication between those clients.
1452 See more information about how this works technically in [SILC2].
1454 Other choice is to entirely use keys that are not sent through
1455 the SILC network at all. This significantly adds security. This key
1456 would be pre-shared-key that is known by both of the clients. Both
1457 agree about using the key and starts sending packets that indicate
1458 that the private message is secured using private message key. This
1459 is the technical aspect mentioned previously that is described
1462 If the private message keys are not set to be used, which is the
1463 case by default in SILC, the private messages are secured by using
1464 normal session keys established by SILC Key Exchange protocol.
1470 4.7 Channel Message Sending and Reception
1472 Channel messages are delivered to group of users. The group forms a
1473 channel and all clients on the channel receives messages sent to the
1476 Channel messages are destined to channel by specifying the Channel ID
1477 as Destination ID in the SILC Packet Header. The server must then
1478 distribute the message to all clients on the channel by sending the
1479 channel message destined explicitly to a client on the channel.
1481 See [SILC2] for describtion of channel message encryption and decryption
1486 4.8 Session Key Regeneration
1488 Session keys should be regenerated peridiocally, say, once in an hour.
1489 The re-key process is started by sending SILC_PACKET_REKEY packet to
1490 other end, to indicate that re-key must be performed.
1492 If perfect forward secrecy (PFS) flag was selected in the SILC Key
1493 Exchange protocol [SILC3] the re-key must cause new key exchange with
1494 SKE protocol. In this case the protocol is secured with the old key
1495 and the protocol results to new key material. See [SILC3] for more
1496 information. After the SILC_PACKET_REKEY packet is sent the sender
1497 will perform the SKE protocol.
1499 If PFS flag was not set, which is the default case, then re-key is done
1500 without executing SKE protocol. In this case, the new key is created by
1501 hashing the old key with hash function selected earlier in the SKE
1502 protocol. If the digest length of the hash function is too short for the
1503 key, then the key is distributed as described in section Processing the
1504 Key Material in [SILC3]. After both parties has regenerated the session
1505 key, both send SILC_PACKET_REKEY_DONE packet to each other. These packets
1506 are still secured with the old key. After these packets, following
1507 packets must be protected with the new key.
1511 4.9 Command Sending and Reception
1513 Client usually sends the commands in the SILC network. In this case
1514 the client simply sends the command packet to server and the server
1515 processes it and replies with command reply packet.
1517 However, if the server is not able to process the command, it is usually
1518 sent to the server's router. This is case for example with commands such
1519 as, SILC_COMMAND_JOIN and SILC_COMMAND_WHOIS commands. However, there
1520 are other commands as well. For example, if client sends the WHOIS
1521 command requesting specific information about some client the server must
1522 send the WHOIS command to router so that all clients in SILC network
1523 are searched. The router, on the other hand, sends the WHOIS command
1524 to further to receive the exact information about the requested client.
1525 The WHOIS command travels all the way to the server who owns the client
1526 and it replies with command reply packet. Finally, the server who
1527 sent the command receives the command reply and it must be able to
1528 determine which client sent the original command. The server then
1529 sends command reply to the client. Implementations should have some
1530 kind of cache to handle, for example, WHOIS information. Servers
1531 and routers along the route could all cache the information for faster
1532 referencing in the future.
1534 The commands sent by server may be sent hop by hop until someone is able
1535 to process the command. However, it is preferred to destine the command
1536 as precisely as it is possible. In this case, other routers en route
1537 must route the command packet by checking the true sender and true
1538 destination of the packet. However, servers and routers must not route
1539 command reply packets to clients coming from other server. Client
1540 must not accept command reply packet originated from anyone else but
1541 from its own server.
1548 5.1 SILC Commands Syntax
1550 This section briefly describes the syntax of the command notions
1551 in this document. Every field in command is separated from each
1552 other by whitespaces (` ') indicating that each field is independent
1553 argument and each argument must have own Command Argument Payload.
1554 The number of maximum arguments are defined with each command
1555 separately. The Command Argument Payload is described in [SILC2].
1557 Every command defines specific number for each argument. Currently,
1558 they are defined in ascending order; first argument has number one
1559 (1), second has number two (2) and so on. This number is set into the
1560 Argument Type field in the Command Argument Payload. This makes it
1561 possible to send the arguments in free order as the number must be
1562 used to identify the type of the argument. This makes is it also
1563 possible to have multiple optional arguments in commands and in
1564 command replies. The number of argument is marked in parentheses
1565 before the actual argument.
1572 Example: Arguments: (1) <nickname> (2) <username@host>
1576 Every command replies with Status Payload. This payload tells the
1577 sender of the command whether the command was completed succefully or
1578 whether there was an error. If error occured the payload includes the
1579 error type. In the next section the Status Payload is not described
1580 as it is common to all commands and has been described here. Commands
1581 may reply with other arguments as well. These arguments are command
1582 specific and are described in the next section.
1591 Arguments: (1) <nickname>[@<server>] (2) <message>
1594 The command has maximum of 3 arguments. However, only first
1595 and second arguments are mandatory.
1597 First argument <nickname> is mandatory but may have optional
1598 <nickname@server> format as well. Second argument is mandatory
1599 <message> argument. Third argument is optional <count> argument.
1601 The numbers in parentheses are the argument specific numbers
1602 that specify the type of the argument in Command Argument Payload.
1603 The receiver always knows that, say, argument number two (2) is
1604 <message> argument, regardles of the ordering of the arguments in
1605 the Command Payload.
1607 Reply messages to the command:
1610 Arguments: (1) <Status Payload> (2) [<channel list>]
1611 (3) <idle time> (4) [<away message>]
1613 This command may reply with maximum of 4 arguments. However,
1614 only the first and third arguments are mandatory. The numbers
1615 in the parentheses have the same meaning as in the upper
1616 command sending specification.
1618 Every command reply with <Status Payload>, it is mandatory
1619 argument for all command replies and for this reason it is not
1620 described in the command reply descriptions.
1627 SILC_STATUS_ERR_TOO_MANY_TARGETS
1628 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1629 SILC_STATUS_ERR_NO_SUCH_NICK
1631 Every command reply also defines set of status message that it
1632 may return inside the <Status Payload>. All status messages
1633 are defined in the section 5.3 SILC Command Status Types.
1638 5.2 SILC Commands List
1640 This section lists all SILC commands, however, it is expected that a
1641 implementation and especially client implementation has many more
1642 commands that has only local affect. These commands are official
1643 SILC commands that has both client and server sides and cannot be
1644 characterized as local commands.
1646 List of all defined commands in SILC follows.
1651 None. This is reserved command and must not be sent.
1654 2 SILC_COMMAND_WHOIS
1657 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1659 Whois. Whois command is used to query various information about
1660 specific user. The user maybe requested by their nickname and
1661 server name. The query may find multiple matching users as
1662 there are no unique nicknames in the SILC. The <count> option
1663 maybe given to narrow down the number of accepted results. If
1664 this is not defined there are no limit of accepted results.
1665 The query may also be narrowed down by defining the server name
1668 To prevent miss-use of this service wildcards in the nickname
1669 or in the servername are not permitted. It is not allowed
1670 to request all users on some server. The WHOIS requests must
1671 be based on specific nickname request.
1673 The WHOIS request must be always forwarded to router by server
1674 so that all users are searched. However, the server still must
1675 search its locally connected clients. The server must send
1676 this command to the server who owns the requested client. That
1677 server must reply to the command.
1679 Reply messages to the command:
1682 Arguments: (1) <Status Payload> (2) <Client ID>
1683 (3) <nickname>[@<server>] (4) <username@host>
1684 (5) <real name> (6) [<channel list>]
1687 This command may reply with several command reply messages to
1688 form a list of results. In this case the status payload will
1689 include STATUS_LIST_START status in the first reply and
1690 STATUS_LIST_END in the last reply to indicate the end of the
1691 list. If there are only one reply the status is set to normal
1694 The command replies include the Client ID of the nickname,
1695 nickname and servername, username and hostnamea and users real
1696 name. Client should process these replies only after the last
1697 reply has been received with the STATUS_LIST_END status. If the
1698 <count> option were defined in the query there will be only
1699 <count> many replies from the server.
1704 SILC_STATUS_LIST_START
1705 SILC_STATUS_LIST_END
1706 SILC_STATUS_ERR_NO_SUCH_NICK
1707 SILC_STATUS_ERR_WILDCARDS
1708 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1709 SILC_STATUS_ERR_TOO_MANY_PARAMS
1712 3 SILC_COMMAND_WHOWAS
1715 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1717 Whowas. This command is used to query history information about
1718 specific user. The user maybe requested by their nickname and
1719 server name. The query may find multiple matching users as there
1720 are no unique nicknames in the SILC. The <count> option maybe
1721 given to narrow down the number of accepted results. If this
1722 is not defined there are no limit of accepted results. The query
1723 may also be narrowed down by defining the server name of the
1726 To prevent miss-use of this service wildcards in the nickname
1727 or in the servername are not permitted. The WHOWAS requests must
1728 be based on specific nickname request.
1730 The WHOWAS request must be always forwarded to router by server
1731 so that all users are searched. However, the server still must
1732 search its locally connected clients.
1734 Reply messages to the command:
1737 Arguments: (1) <Status Payload> (2) <nickname>[@<server>]
1740 This command may reply with several command reply messages to form
1741 a list of results. In this case the status payload will include
1742 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1743 the last reply to indicate the end of the list. If there are only
1744 one reply the status is set to normal STATUS_OK.
1746 The command replies with nickname and username and hostname.
1747 Every server must keep history for some period of time of its
1748 locally connected clients.
1753 SILC_STATUS_LIST_START
1754 SILC_STATUS_LIST_END
1755 SILC_STATUS_ERR_NO_SUCH_NICK
1756 SILC_STATUS_ERR_WILDCARDS
1757 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1758 SILC_STATUS_ERR_TOO_MANY_PARAMS
1761 4 SILC_COMMAND_IDENTIFY
1764 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1766 Identify. Identify command is almost analogous to WHOIS command,
1767 except that it does not return as much information. Only relevant
1768 information such as Client ID is returned. This is usually used
1769 to get the Client ID of a client used in the communication with
1772 The query may find multiple matching users as there are no unique
1773 nicknames in the SILC. The <count> option maybe given to narrow
1774 down the number of accepted results. If this is not defined there
1775 are no limit of accepted results. The query may also be narrowed
1776 down by defining the server name of the nickname.
1778 To prevent miss-use of this service wildcards in the nickname
1779 or in the servername are not permitted. It is not allowed
1780 to request all users on some server. The IDENTIFY requests must
1781 be based on specific nickname request.
1783 Implementations may not want to give interface access to this
1784 commands as it is hardly a command that would be used a end user.
1785 However, it must be implemented as it is used with private message
1788 The IDENTIFY must be always forwarded to router by server so that
1789 all users are searched. However, server must still search its
1790 locally connected clients.
1792 Reply messages to the command:
1795 Arguments: (1) <Status Payload> (2) <Client ID>
1796 (3) [<nickname>[@<server>]] (4) [<username@host>]
1798 This command may reply with several command reply messages to form
1799 a list of results. In this case the status payload will include
1800 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1801 the last reply to indicate the end of the list. If there are only
1802 one reply the status is set to normal STATUS_OK.
1804 The command replies with Client ID of the nickname and if more
1805 information is available it may reply with nickname and username
1806 and hostname. If the <count> option were defined in the query
1807 there will be only <count> many replies from the server.
1812 SILC_STATUS_LIST_START
1813 SILC_STATUS_LIST_END
1814 SILC_STATUS_ERR_NO_SUCH_NICK
1815 SILC_STATUS_ERR_WILDCARDS
1816 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1817 SILC_STATUS_ERR_TOO_MANY_PARAMS
1823 Arguments: (1) <nickname>
1825 Set/change nickname. This command is used to set nickname for
1826 user. There is no limit of the length of the nickname in SILC.
1827 Nickname must not include any spaces (` '), non-printable
1828 characters, commas (`,') and any wildcard characters. Note:
1829 nicknames in SILC are case-sensitive which must be taken into
1830 account when searching clients by nickname.
1832 Reply messages to the command:
1835 Arguments: (1) <Status Payload> (2) <New ID Payload>
1837 This command is replied always with New ID Payload that is
1838 generated by the server every time user changes their nickname.
1839 Client receiving this payload must start using the received
1840 Client ID as its current valid Client ID. The New ID Payload
1841 is described in [SILC2].
1846 SILC_STATUS_ERR_WILDCARDS
1847 SILC_STATUS_ERR_NICKNAME_IN_USE
1848 SILC_STATUS_ERR_BAD_NICKNAME
1849 SILC_STATUS_ERR_NOT_REGISTERED
1850 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1851 SILC_STATUS_ERR_TOO_MANY_PARAMS
1857 Arguments: (1) [<Channel ID>] [<server>]
1859 The list command is used to list channels and their topics on
1860 current server. If the <Channel ID> parameter is used, only the
1861 status of that channel is displayed. Secret channels are not
1862 listed at all. Private channels are listed with status indicating
1863 that the channel is private.
1865 If the <server> argument is specified the specified server's
1866 channels are listed. In this case the command must be sent to
1867 the server who owns the channel that was requested.
1869 Reply messages to the command:
1872 Arguments: (1) <Status Payload> (2) <Channel ID>
1873 (3) <channel> (4) <topic>
1875 This command may reply with several command reply messages to form
1876 a list of results. In this case the status payload will include
1877 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1878 the last reply to indicate the end of the list. If there are only
1879 one reply the status is set to normal STATUS_OK.
1881 This command replies with Channel ID, name and the topic of the
1882 channel. If the channel is private channel the <topic> includes
1888 SILC_STATUS_LIST_START
1889 SILC_STATUS_LIST_END
1890 SILC_STATUS_ERR_WILDCARDS
1891 SILC_STATUS_ERR_NOT_REGISTERED
1892 SILC_STATUS_ERR_TOO_MANY_PARAMS
1893 SILC_STATUS_ERR_NO_SUCH_CHANNEL
1894 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
1895 SILC_STATUS_ERR_NO_SUCH_SERVER
1898 7 SILC_COMMAND_TOPIC
1901 Arguments: (1) <Channel ID> (2) [<server>]]
1903 This command is used to change or view the topic of a channel.
1904 The topic for channel <Channel ID> is returned if there is no
1905 <topic> given. If the <topic> parameter is present, the topic
1906 for that channel will be changed, if the channel modes permit
1909 Reply messages to the command:
1912 Arguments: (1) <Status Payload> (2) [<topic>]
1914 The command may reply with the topic of the channel if it is
1920 SILC_STATUS_ERR_NOT_ON_CHANNEL
1921 SILC_STATUS_ERR_WILDCARDS
1922 SILC_STATUS_ERR_NOT_REGISTERED
1923 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1924 SILC_STATUS_ERR_NO_SUCH_CHANNEL
1925 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
1926 SILC_STATUS_ERR_NO_CHANNEL_ID
1927 SILC_STATUS_ERR_BAD_CHANNEL_ID
1928 SILC_STATUS_ERR_TOO_MANY_PARAMS
1929 SILC_STATUS_ERR_NO_CHANNEL_PRIV
1932 8 SILC_COMMAND_INVITE
1935 Arguments: (1) <Client ID> (2) <Channel ID>
1937 This command is used to invite other clients to join to the
1938 channel. The <Client ID> argument is the target client's ID that
1939 is being invited. The <Channel ID> is the Channel ID of the
1940 requested channel. The sender of this command must be on the
1941 channel. This command must fail if the requested channel does
1942 not exist, the requested client is already on the channel or if
1943 the channel is invite only channel and the caller of this command
1944 does not have at least channel operator privileges.
1946 Reply messages to the command:
1949 Arguments: (1) <Status Payload>
1951 This command replies only with Status Payload.
1956 SILC_STATUS_ERR_NOT_REGISTERED
1957 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1958 SILC_STATUS_ERR_TOO_MANY_PARAMS
1959 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
1960 SILC_STATUS_ERR_NO_CLIENT_ID
1961 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
1962 SILC_STATUS_ERR_NO_CHANNEL_ID
1963 SILC_STATUS_ERR_NOT_ON_CHANNEL
1964 SILC_STATUS_ERR_USER_ON_CHANNEL
1970 Arguments: (1) [<quit message>]
1972 This command is used by client to end SILC session. The server
1973 must close the connection to a client which sends this command.
1974 if <quit message> is given it will be sent to other clients on
1975 channel if the client is on channel when quitting.
1977 Reply messages to the command:
1979 This command does not reply anything.
1982 10 SILC_COMMAND_KILL
1985 Arguments: (1) <Client ID> (2) [<comment>]
1987 This command is used by SILC operators to remove a client from
1988 SILC network. The removing has temporary effects and client may
1989 reconnect to SILC network. The <Client ID> is the client to be
1990 removed from SILC. The <comment> argument may be provided to
1991 give to the removed client some information why it was removed
1994 Reply messages to the command:
1997 Arguments: (1) <Status Payload>
1999 This command replies only with Status Payload.
2004 SILC_STATUS_ERR_WILDCARDS
2005 SILC_STATUS_ERR_NOT_REGISTERED
2006 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2007 SILC_STATUS_ERR_TOO_MANY_PARAMS
2008 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2009 SILC_STATUS_ERR_NO_CLIENT_ID
2015 11 SILC_COMMAND_INFO
2018 Arguments: (1) [<server>]
2020 This command is used to fetch various information about a server.
2021 If <server> argument is specified the command must be sent to
2022 the requested server.
2024 Reply messages to the command:
2027 Arguments: (1) <Status Payload> (2) <Server ID>
2030 This command replies with the Server ID of the server and a
2031 string which tells the information about the server.
2036 SILC_STATUS_ERR_WILDCARDS
2037 SILC_STATUS_ERR_NOT_REGISTERED
2038 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2039 SILC_STATUS_ERR_TOO_MANY_PARAMS
2040 SILC_STATUS_ERR_NO_SUCH_SERVER
2043 12 SILC_COMMAND_CONNECT
2046 Arguments: (1) <Server ID>
2047 (2) [<remote server/router>[:<port>]]
2049 This command is used by operators to force a server to try to
2050 establish a new connection to another router (if the connecting
2051 server is normal server) or server (if the conneceting server is
2052 router server). Operator may specify the server/router to be
2053 connected by setting <remote server> argument.
2055 Reply messages to the command:
2058 Arguments: (1) <Status Payload>
2060 This command replies only with Status Payload.
2067 SILC_STATUS_ERR_WILDCARDS
2068 SILC_STATUS_ERR_NOT_REGISTERED
2069 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2070 SILC_STATUS_ERR_TOO_MANY_PARAMS
2071 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2072 SILC_STATUS_ERR_NO_SERVER_PRIV
2073 SILC_STATUS_ERR_NO_ROUTER_PRIV
2076 13 SILC_COMMAND_PING
2079 Arguments: (1) <Server ID>
2081 This command is used by client and server to test the communication
2082 channel to its server if one suspects that the communication is not
2083 working correctly. The <Server ID> is the ID of the server the
2084 sender is connected to.
2086 Reply messages to the command:
2089 Arguments: (1) <Status Payload>
2091 This command replies only with Status Payload. Server returns
2092 SILC_STATUS_OK in Status Payload if pinging was successful.
2097 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2098 SILC_STATUS_ERR_TOO_MANY_PARAMS
2099 SILC_STATUS_ERR_NO_SERVER_ID
2100 SILC_STATUS_ERR_NO_SUCH_SERVER
2101 SILC_STATUS_ERR_NOT_REGISTERED
2104 14 SILC_COMMAND_OPER
2107 Arguments: (1) <username> (2) <authentication data>
2109 This command is used by normal client to obtain server operator
2110 privileges on some server or router. Note that router operator
2111 has router privileges that supersedes the server operator
2112 privileges and this does not obtain those privileges. Client
2113 must use SILCOPER command to obtain router level privileges.
2115 The <username> is the username set in the server configurations
2116 as operator. The <authentication data> is the data that the
2117 client is authenticated against. It may be passphrase prompted
2118 for user on client's screen or it may be public key
2119 authentication data (data signed with private key), or
2122 Reply messages to the command:
2125 Arguments: (1) <Status Payload>
2127 This command replies only with Status Payload.
2132 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2133 SILC_STATUS_ERR_TOO_MANY_PARAMS
2134 SILC_STATUS_ERR_NOT_REGISTERED
2135 SILC_STATUS_ERR_BAD_PASSWORD
2136 SILC_STATUS_ERR_AUTH_FAILED
2139 15 SILC_COMMAND_JOIN
2142 Arguments: (1) <channel> (2) [<passphrase>]
2145 Join to channel/create new channel. This command is used to
2146 join to a channel. If the channel does not exist the channel is
2147 created. If server is normal server this command must be forwarded
2148 to router who will create the channel. The channel may be protected
2149 with passphrase. If this is the case the passphrase must be sent
2150 along the join command.
2152 The name of the <channel> must not include any spaces (` '),
2153 non-printable characters, commas (`,') or any wildcard characters.
2155 Cipher to be used to secure the traffic on the channel may be
2156 requested by sending the name of the requested <cipher>. This
2157 is used only if the channel does not exist and is created. If
2158 the channel already exists the cipher set previously for the
2159 channel will be used to secure the traffic.
2161 The server must check whether the user is allowed to join to
2162 the requested channel. Various modes set to the channel affect
2163 the ability of the user to join the channel. These conditions
2166 o The user must be invited to the channel if the channel
2167 is invite-only channel.
2169 o The Client ID/nickname/username/hostname must not match
2172 o The correct passphrase must be provided if passphrase
2173 is set to the channel.
2175 o The user count limit, if set, must not be reached.
2177 Reply messages to the command:
2180 Arguments: (1) <Status Payload> (2) <channel>
2181 (3) <Channel ID> (4) <channel mode mask>
2184 This command replies with the channel name requested by the
2185 client, channel ID of the channel and topic of the channel
2186 if it exists. It also replies with the channel mode mask
2187 which tells all the modes set on the channel. If the
2188 channel is created the mode mask is zero (0).
2190 Client must not start transmitting to the channel even after
2191 server has replied to this command. Client is permitted to
2192 start transmitting on channel after server has sent packet
2193 SILC_PACKET_CHANNEL_KEY to the client.
2198 SILC_STATUS_ERR_WILDCARDS
2199 SILC_STATUS_ERR_NOT_REGISTERED
2200 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2201 SILC_STATUS_ERR_TOO_MANY_PARAMS
2202 SILC_STATUS_ERR_BAD_PASSWORD
2203 SILC_STATUS_ERR_CHANNEL_IS_FULL
2204 SILC_STATUS_ERR_NOT_INVITED
2205 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
2206 SILC_STATUS_ERR_BAD_CHANNEL
2207 SILC_STATUS_ERR_USER_ON_CHANNEL
2210 16 SILC_COMMAND_MOTD
2213 Arguments: (1) <server>
2215 This command is used to query the Message of the Day of a server.
2217 Reply messages to the command:
2220 Arguments: (1) <Status Payload> (2) [<motd>]
2222 This command replies with the motd message if it exists.
2227 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2228 SILC_STATUS_ERR_TOO_MANY_PARAMS
2229 SILC_STATUS_ERR_NOT_REGISTERED
2230 SILC_STATUS_ERR_NO_SUCH_SERVER
2233 17 SILC_COMMAND_UMODE
2236 Arguments: (1) <Client ID> (2) <client mode mask>
2238 This command is used by client to set/unset modes for itself.
2239 However, there are some modes that the client may not set itself,
2240 but they will be set by server. However, client may unset any
2241 mode. Modes may be masked together ORing them thus having
2242 several modes set. Client must keep its client mode mask
2243 locally so that the mode setting/unsetting would work without
2244 problems. Client may change only its own modes.
2246 Following client modes are defined:
2248 0x0000 SILC_UMODE_NONE
2250 No specific mode for client. This is the initial
2251 setting when new client is created. The client is
2255 0x0001 SILC_UMODE_SERVER_OPERATOR
2257 Marks the user as server operator. Client cannot
2258 set this mode itself. Server sets this mode to the
2259 client when client attains the server operator
2260 privileges by SILC_COMMAND_OPER command. Client
2261 may unset the mode itself.
2264 0x0002 SILC_UMODE_ROUTER_OPERATOR
2266 Marks the user as router (SILC) operator. Client
2267 cannot this mode itself. Router sets this mode to
2268 the client when client attains the router operator
2269 privileges by SILC_COMMAND_SILCOPER command. Client
2270 may unset the mode itself.
2272 Reply messages to the command:
2275 Arguments: (1) <Status Payload> (2) <client mode mask>
2277 This command replies with the changed client mode mask that
2278 the client is required to keep locally.
2284 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2285 SILC_STATUS_ERR_TOO_MANY_PARAMS
2286 SILC_STATUS_ERR_NOT_REGISTERED
2287 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2288 SILC_STATUS_ERR_BAD_CLIENT_ID
2289 SILC_STATUS_ERR_NOT_YOU
2290 SILC_STATUS_ERR_UNKNOWN_MODE
2291 SILC_STATUS_ERR_NO_RECIPIENT
2292 SILC_STATUS_ERR_NO_CLIENT_ID
2295 18 SILC_COMMAND_CMODE
2298 Arguments: (1) <Channel ID> (2) <channel mode mask>
2299 (3) [<user limit>] (4) [<passphrase>]
2300 (5) [<ban mask>] (6) [<invite list>]
2301 (7) [<Client ID>] (8) [<cipher>[:<key len>]]
2303 This command is used by client to set or change channel flags on
2304 a channel. Channel has several modes that set various properties
2305 of a channel. Modes may be masked together by ORing them thus
2306 having several modes set. The <Channel ID> is the ID of the
2307 target channel. The client changing channel mode must be on
2308 the same channel and poses sufficient privileges to be able to
2311 Following channel modes are defined:
2313 0x0000 SILC_CMODE_NONE
2315 No specific mode on channel. This is the default when
2316 channel is created. This means that channel is just plain
2320 0x0001 SILC_CMODE_PRIVATE
2322 Channel is private channel. Private channels are shown
2323 in the channel list listed with SILC_COMMAND_LIST command
2324 with indicatioin that the channel is private. Also,
2325 client on private channel will no be detected to be on
2326 the channel as the channel is not shown in the client's
2327 currently joined channel list. Channel founder and
2328 channel operator may set/unset this mode.
2330 Typical implementation would use [+|-]p on user interface
2331 to set/unset this mode.
2334 0x0002 SILC_CMODE_SECRET
2336 Channel is secret channel. Secret channels are not shown
2337 in the list listed with SILC_COMMAND_LIST command. Secret
2338 channels can be considered to be invisible channels.
2339 Channel founder and channel operator may set/unset this
2342 Typical implementation would use [+|-]s on user interface
2343 to set/unset this mode.
2346 0x0004 SILC_CMODE_PRIVKEY
2348 Channel uses private channel key to protect the traffic
2349 on the channel. When this mode is set the client will be
2350 responsible to set the key it wants to use to encrypt and
2351 decrypt the traffic on channel. Server generated channel
2352 keys are not used at all. This mode provides additional
2353 security as clients on channel may agree to use private
2354 channel key that even servers do not know. Naturally,
2355 this requires that every client on the channel knows
2356 the key before hand (it is considered to be pre-shared-
2357 key). This specification does not define how the private
2358 channel key is set as it is entirely local setting on
2361 As it is local setting it is possible to have several
2362 private channel keys on one channel. In this case several
2363 clients can talk on same channel but only those clients
2364 that share the key with the message sender will be able
2365 to hear the talking. Client should not display those
2366 message for the end user that it is not able to decrypt
2367 when this mode is set.
2369 Only channel founder may set/unset this mode. If this
2370 mode is unset the server will distribute new channel
2371 key to all clients on the channel which will be used
2374 Typical implementation would use [+|-]k on user interface
2375 to set/unset this mode.
2378 0x0008 SILC_CMODE_INVITE
2380 Channel is invite only channel. Client may join to this
2381 channel only if it is invited to the channel. Channel
2382 founder and channel operator may set/unset this mode.
2384 Typical implementation would use [+|-]i on user interface
2385 to set/unset this mode.
2388 0x0010 SILC_CMODE_TOPIC
2390 The topic of the channel may only be set by client that
2391 is channel founder or channel operator. Normal clients
2392 on channel will not be able to set topic when this mode
2393 is set. Channel founder and channel operator may set/
2396 Typical implementation would use [+|-]t on user interface
2397 to set/unset this mode.
2400 0x0020 SILC_CMODE_ULIMIT
2402 User limit has been set to the channel. New clients
2403 may not join to the channel when the limit set is
2404 reached. Channel founder and channel operator may set/
2405 unset the limit. The <user limit> argument is the
2406 number of limited users.
2408 Typical implementation would use [+|-]l on user interface
2409 to set/unset this mode.
2412 0x0040 SILC_CMODE_PASSPHRASE
2414 Passphrase has been set to the channel. Client may
2415 join to the channel only if it is able to provide the
2416 correct passphrase. Setting passphrases to channel
2417 is entirely safe as all commands are protected in the
2418 SILC network. Only channel founder may set/unset
2419 the passphrase. The <passphrase> argument is the
2422 Typical implementation would use [+|-]a on user interface
2423 to set/unset this mode.
2426 0x0080 SILC_CMODE_BAN
2428 Ban mask has been set to the channel. The ban mask
2429 may be used to ban specific clients to join the channel.
2430 The <ban mask> argument is the set ban mask. When
2431 unsetting a ban mask the mask must be provided as
2432 argument. Channel founder and channel operator may
2433 set/unset this mode. Channel founder may not be
2434 added to the ban list.
2436 Typical implementation would use [+|-]b on user interface
2437 to set/unset this mode.
2440 0x0100 SILC_CMODE_INVITE
2442 Invite list has been set to the channel. The invite list
2443 can be used to mark the clients that is able to join
2444 channel without being invited when the channel is set to
2445 be invite-only channel. The <invite list> argument is the
2446 set invite mask. When unsetting entry from the invite list
2447 the entry must be provided as argument. Channel founder and
2448 channel operator may set/unset this mode.
2450 Typical implementation would use [+|-]I on user interface
2451 to set/unset this mode.
2454 0x0200 SILC_CMODE_OPERATOR
2456 Sets channel operator privileges on the channel for a
2457 client on the channel. The <Client ID> argument is the
2458 target client on the channel. Channel founder and
2459 channel operator may set/unset (promote/demote) this
2462 Typical implementation would use [+|-]o on user interface
2463 to set/unset this mode.
2466 0x0400 SILC_CMODE_CIPHER
2468 Sets specific cipher to be used to protect channel
2469 traffic. The <cipher> argument is the requested cipher.
2470 When set or unset the server must re-generate new
2471 channel key. If <key len> argument is specified with
2472 <cipher> argument the new key is generated of <key len>
2475 Typical implementation would use [+|-]c on user interface
2476 to set/unset this mode.
2479 To make the mode system work, client must keep the channel mode
2480 mask locally so that the mode setting and unsetting would work
2481 without problems. The client receives the initial channel mode
2482 mask when it joins to the channel. When the mode changes on
2483 channel the server distributes the changed channel mode mask to
2484 all clients on the channel by sending SILC_COMMAND_CMODE command
2488 Reply messages to the command:
2491 Arguments: (1) <Status Payload> (2) <channel mode mask>
2493 This command replies with the changed channel mode mask that
2494 client is required to keep locally. The same mask is also
2495 sent to all clients on channel by sending additional command
2501 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2502 SILC_STATUS_ERR_TOO_MANY_PARAMS
2503 SILC_STATUS_ERR_NOT_REGISTERED
2504 SILC_STATUS_ERR_NOT_ON_CHANNEL
2505 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2506 SILC_STATUS_ERR_BAD_CHANNEL_ID
2507 SILC_STATUS_ERR_NO_CHANNEL_ID
2508 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2509 SILC_STATUS_ERR_UNKNOWN_MODE
2510 SILC_STATUS_ERR_NO_CLIENT_ID
2515 19 SILC_COMMAND_KICK
2518 Arguments: (1) <channel> (2) <Client ID>
2521 This command is used by channel operators to remove a client from
2522 channel. The <channel> argument is the channel the client to be
2523 removed is on currently. Note that the "kicker" must be on the same
2524 channel. If <comment> is provided it will be sent to the removed
2527 Reply messages to the command:
2530 Arguments: (1) <Status Payload>
2532 This command replies only with Status Payload.
2537 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2538 SILC_STATUS_ERR_TOO_MANY_PARAMS
2539 SILC_STATUS_ERR_NOT_REGISTERED
2540 SILC_STATUS_ERR_NO_SUCH_CHANNEL
2541 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2542 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2543 SILC_STATUS_ERR_NO_CLIENT_ID
2546 20 SILC_COMMAND_RESTART
2551 This command may only be used by server operator to force a
2552 server to restart itself.
2554 Reply messages to the command:
2557 Arguments: (1) <Status Payload>
2559 This command replies only with Status Payload.
2566 SILC_STATUS_ERR_NOT_REGISTERED
2567 SILC_STATUS_ERR_NO_SERVER_PRIV
2570 21 SILC_COMMAND_CLOSE
2573 Arguments: (1) <Server ID>
2575 This command is used only by operator to close connection to a
2576 remote site. The <Server ID> argument is the ID of the remote
2577 site and must be valid.
2579 Reply messages to the command:
2582 Arguments: (1) <Status Payload>
2584 This command replies only with Status Payload.
2591 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2592 SILC_STATUS_ERR_TOO_MANY_PARAMS
2593 SILC_STATUS_ERR_NOT_REGISTERED
2594 SILC_STATUS_ERR_NO_SUCH_SERVER
2595 SILC_STATUS_ERR_NO_SERVER_PRIV
2596 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2604 This command is used only by operator to shutdown the server.
2605 All connections to the server will be closed and the server is
2608 Reply messages to the command:
2613 Arguments: (1) <Status Payload>
2615 This command replies only with Status Payload.
2620 SILC_STATUS_ERR_NOT_REGISTERED
2621 SILC_STATUS_ERR_NO_SERVER_PRIV
2624 23 SILC_COMMAND_SILCOPER
2627 Arguments: (1) <username> (2) <authentication data>
2629 This command is used by normal client to obtain router operator
2630 privileges (also known as SILC operator) on some router. Note
2631 that router operator has router privileges that supersedes the
2632 server operator privileges.
2634 The <username> is the username set in the server configurations
2635 as operator. The <authentication data> is the data that the
2636 client is authenticated against. It may be passphrase prompted
2637 for user on client's screen or it may be public key
2638 authentication data (data signed with private key), or
2641 Difference between router operator and server operator is that
2642 router operator is able to handle cell level properties while
2643 server operator (even on router server) is able to handle only
2644 local properties, such as, local connections and normal server
2647 Reply messages to the command:
2650 Arguments: (1) <Status Payload>
2652 This command replies only with Status Payload.
2657 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2658 SILC_STATUS_ERR_TOO_MANY_PARAMS
2659 SILC_STATUS_ERR_NOT_REGISTERED
2660 SILC_STATUS_ERR_BAD_PASSWORD
2661 SILC_STATUS_ERR_AUTH_FAILED
2664 24 SILC_COMMAND_LEAVE
2667 Arguments: (1) <Channel ID>
2669 This command is used by client to leave a channel the client is
2670 joined to. After a client has leaved the channel the server
2671 must create new key for the channel and distribute to all clients
2672 still currently on the channel.
2674 Reply messages to the command:
2677 Arguments: (1) <Status Payload>
2679 This command replies only with Status Payload.
2684 SILC_STATUS_ERR_NOT_REGISTERED
2685 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2686 SILC_STATUS_ERR_TOO_MANY_PARAMS
2687 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2688 SILC_STATUS_ERR_BAD_CHANNEL_ID
2689 SILC_STATUS_ERR_NO_CHANNEL_ID
2692 25 SILC_COMMAND_NAMES
2695 Arguments: (1) <Channel ID>
2697 This command is used to list user names currently on the requested
2698 channel; argument <Channel ID>. The server must resolve the
2699 user names and send a comma (`,') separated list of user names
2700 on the channel. Server or router may resolve the names by sending
2701 SILC_COMMAND_WHOIS commands.
2703 If the requested channel is a private or secret channel, this
2704 command must not send the list of users, as private and secret
2705 channels cannot be seen by outside. In this case the returned
2706 name list may include a indication that the server could not
2707 resolve the names of the users on the channel.
2709 Reply messages to the command:
2712 Arguments: (1) <Status Payload> (2) <Channel ID>
2713 (3) <name list> (4) <Client ID list>
2715 This command replies with the Channel ID of the requested channel,
2716 comma separated list of users on the channel and Client ID list
2717 of the users on the list. The Client ID list has Client ID's
2718 of all users in the list. First Client ID in the list must be
2719 the Client ID of the first user in <name list>. The Client ID
2720 List is formed by adding Client ID's each after each. Note that
2721 the Client ID list is binary data.
2726 SILC_STATUS_ERR_NOT_REGISTERED
2727 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2728 SILC_STATUS_ERR_TOO_MANY_PARAMS
2729 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2730 SILC_STATUS_ERR_BAD_CHANNEL_ID
2731 SILC_STATUS_ERR_NO_CHANNEL_ID
2732 SILC_STATUS_ERR_NOT_ON_CHANNEL
2737 Currently undefined commands.
2740 255 SILC_COMMAND_MAX
2742 Reserved command. This must not be sent.
2747 5.3 SILC Command Status Types
2750 5.3.1 SILC Command Status Payload
2752 Command Status Payload is sent in command reply messages to indicate
2753 the status of the command. The payload is one of argument in the
2754 command thus this is the data area in Command Argument Payload described
2755 in [SILC2]. The payload is only 2 bytes of length. Following diagram
2756 represents the Command Status Payload (field is always in MSB order).
2762 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
2763 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2765 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2769 Figure 5: SILC Command Status Payload
2773 o Status Message (2 bytes) - Indicates the status message.
2774 All Status messages are described in the next section.
2779 5.3.2 SILC Command Status List
2781 Command Status messages are returned in the command reply messages
2782 to indicate whether the command were executed without errors. If error
2783 has occured the status tells which error occured. Status payload only
2784 sends numeric reply about the status. Receiver of the payload must
2785 convert the numeric values into human readable error messages. The
2786 list of status messages below has an example human readable error
2787 messages that client may display for the user.
2789 List of all defined command status messages following.
2792 Generic status messages:
2796 Ok status. Everything went Ok. The status payload maybe
2797 safely ignored in this case.
2799 1 SILC_STATUS_LIST_START
2801 Start of the list. There will be several command replies and
2802 this reply is the start of the list.
2804 2 SILC_STATUS_LIST_END
2806 End of the list. There were several command replies and this
2807 reply is the last of the list. There won't be other replies
2808 beloning to this list after this one.
2812 Currently undefined and has been reserved for the future.
2815 Error status message:
2817 10 SILC_STATUS_ERR_NO_SUCH_NICK
2819 "No such nickname". Requested nickname does not exist.
2821 11 SILC_STATUS_ERR_NO_SUCH_CHANNEL
2823 "No such channel". Requested channel name does not exist.
2825 12 SILC_STATUS_ERR_NO_SUCH_SERVER
2827 "No such server". Requested server name does not exist.
2829 13 SILC_STATUS_ERR_TOO_MANY_TARGETS
2831 "Duplicate recipients. No message delivered". Message were
2832 tried to be sent to recipient which has several occurrences in
2835 14 SILC_STATUS_ERR_NO_RECIPIENT
2837 "No recipient given". Command required recipient which was
2840 15 SILC_STATUS_ERR_UNKNOWN_COMMAND
2842 "Unknown command". Command sent to server is unknown by the
2845 16 SILC_STATUS_ERR_WILDCARDS
2847 "Wildcards cannot be used". Wildcards were provided but they
2850 17 SILC_STATUS_ERR_NO_CLIENT_ID
2852 "No Client ID given". Client ID were expected as command
2853 parameter but were not found.
2855 18 SILC_STATUS_ERR_NO_CHANNEL_ID
2857 "No Channel ID given". Channel ID were expected as command
2858 parameter but were not found.
2860 19 SILC_STATUS_ERR_NO_SERVER_ID
2862 "No Serve ID given". Server ID were expected as command
2863 parameter but were not found.
2865 20 SILC_STATUS_ERR_BAD_CLIENT_ID
2867 "Bad Client ID". Client ID provided were erroneous.
2869 21 SILC_STATUS_ERR_BAD_CHANNEL_ID
2871 "Bad Channel ID". Channel ID provided were erroneous.
2873 22 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2875 "No such Client ID". Client ID provided does not exist.
2878 23 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2880 "No such Channel ID". Channel ID provided does not exist.
2882 24 SILC_STATUS_ERR_NICKNAME_IN_USE
2884 "Nickname already exists". Nickname created could not be
2885 registered because number of same nicknames were already set to
2886 maximum. This is not expected to happen in real life but is
2889 25 SILC_STATUS_ERR_NOT_ON_CHANNEL
2891 "You are not on that channel". The command were specified for
2892 client user is not currently on.
2894 26 SILC_STATUS_ERR_USER_ON_CHANNEL
2896 "User already on channel". User were invited on channel they
2899 27 SILC_STATUS_ERR_NOT_REGISTERED
2901 "You have not registered". User executed command that requires
2902 the client to be registered on the server before it may be
2905 28 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2907 "Not enough parameters". Command requires more parameters
2910 29 SILC_STATUS_ERR_TOO_MANY_PARAMS
2912 "Too many parameters". Too many parameters were provided
2915 30 SILC_STATUS_ERR_PERM_DENIED
2917 "Your host is not among the privileged". The client tried to
2918 register on server that does not allow this host to connect.
2920 31 SILC_STATUS_ERR_BANNED_FROM_SERVER
2922 "You are banned from this server". The client tried to register
2923 on server that has explicitly denied this host to connect.
2927 32 SILC_STATUS_ERR_BAD_PASSWORD
2929 "Cannot join channel. Incorrect password". Password provided for
2930 channel were not accepted.
2932 33 SILC_STATUS_ERR_CHANNEL_IS_FULL
2934 "Cannot join channel. Channel is full". The channel is full
2935 and client cannot be joined to it.
2937 34 SILC_STATUS_ERR_NOT_INVITED
2939 "Cannot join channel. You have not been invited". The channel
2940 is invite only channel and client has not been invited.
2942 35 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
2944 "Cannot join channel. You have been banned". The client has
2945 been banned from the channel.
2947 36 SILC_STATUS_ERR_UNKNOWN_MODE
2949 "Unknown mode". Mode provided by the client were unknown to
2952 37 SILC_STATUS_ERR_NOT_YOU
2954 "Cannot change mode for other users". User tried to change
2955 someone else's mode.
2957 38 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2959 "Permission denied. You are not channel operator". Command may
2960 be executed only by channel operator.
2962 39 SILC_STATUS_ERR_NO_SERVER_PRIV
2964 "Permission denied. You are not server operator". Command may
2965 be executed only by server operator.
2967 40 SILC_STATUS_ERR_NO_ROUTER_PRIV
2969 "Permission denied. You are not SILC operator". Command may be
2970 executed only by router (SILC) operator.
2972 41 SILC_STATUS_ERR_BAD_NICKNAME
2974 "Bad nickname". Nickname requested contained illegal characters
2977 42 SILC_STATUS_ERR_BAD_CHANNEL
2979 "Bad channel name". Channel requested contained illegal characters
2982 43 SILC_STATUS_ERR_AUTH_FAILED
2984 "Authentication failed". The authentication data sent as
2985 argument were wrong and thus authentication failed.
2990 6 Security Considerations
2992 Security is central to the design of this protocol, and these security
2993 considerations permeate the specification.
3002 [SILC2] Riikonen, P., "SILC Packet Protocol", Internet Draft,
3005 [SILC3] Riikonen, P., "SILC Key Exchange and Authentication
3006 Protocols", Internet Draft, June 2000.
3008 [IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
3011 [SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
3014 [PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
3017 [SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
3020 [PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
3021 Infrastructure, Certificate and CRL Profile", RFC 2459,
3024 [Schneier] Schneier, B., "Applied Cryptography Second Edition",
3025 John Wiley & Sons, New York, NY, 1996.
3027 [Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
3030 [OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
3031 RFC 2412, November 1998.
3033 [ISAKMP] Maughan D., et al, "Internet Security Association and
3034 Key Management Protocol (ISAKMP)", RFC 2408, November
3037 [IKE] Harkins D., and Carrel D., "The Internet Key Exhange
3038 (IKE)", RFC 2409, November 1998.
3040 [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
3041 Authentication", RFC 2104, February 1997.
3054 EMail: priikone@poseidon.pspt.fi
3056 This Internet-Draft expires 28 Jan 2001