8 .ds RF FORMFEED[Page %]
11 .ds RH 13 September 2000
17 Network Working Group P. Riikonen
19 draft-riikonen-silc-spec-01.txt 13 September 2000
25 Secure Internet Live Conferencing (SILC),
26 Protocol Specification
27 <draft-riikonen-silc-spec-01.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 3.12 SILC Version Detection ................................... 24
110 4 SILC Procedures ............................................... 24
111 4.1 Creating Client Connection ................................ 24
112 4.2 Creating Server Connection ................................ 25
113 4.3 Joining to a Channel ...................................... 26
114 4.4 Channel Key Generation .................................... 27
115 4.5 Private Message Sending and Reception ..................... 27
116 4.6 Private Message Key Generation ............................ 28
117 4.7 Channel Message Sending and Reception ..................... 29
118 4.8 Session Key Regeneration .................................. 29
119 4.9 Command Sending and Reception ............................. 29
120 5 SILC Commands ................................................. 30
121 5.1 SILC Commands Syntax ...................................... 30
122 5.2 SILC Commands List ........................................ 32
123 5.3 SILC Command Status Types ................................. 53
124 5.3.1 SILC Command Status Payload ......................... 53
125 5.3.2 SILC Command Status List ............................ 54
126 6 Security Considerations ....................................... 59
127 7 References .................................................... 59
128 8 Author's Address .............................................. 60
135 Figure 1: SILC Network Topology
136 Figure 2: Communication Inside cell
137 Figure 3: Communication Between Cells
138 Figure 4: SILC Public Key
139 Figure 5: SILC Command Status Payload
145 This document describes a Secure Internet Live Conferencing (SILC)
146 protocol which provides secure conferencing services over insecure
147 network channel. SILC is IRC [IRC] like protocol, however, it is
148 not equivalent to IRC and does not support IRC.
150 Strong cryptographic methods are used to protect SILC packets inside
151 SILC network. Two other Internet Drafts relates very closely to this
152 memo; SILC Packet Protocol [SILC2] and SILC Key Exchange and
153 Authentication Protocols [SILC3].
155 The protocol uses extensively packets as conferencing protocol
156 requires message and command sending. The SILC Packet Protocol is
157 described in [SILC2] and should be read to fully comprehend this
158 document and protocol. [SILC2] also describes the packet encryption
159 and decryption in detail.
161 The security of SILC protocol and for any security protocol for that
162 matter is based on strong and secure key exchange protocol. The SILC
163 Key Exchange protocol is described in [SILC3] along with connection
164 authentication protocol and should be read to fully comprehend this
165 document and protocol.
167 The SILC protocol has been developed to work on TCP/IP network
168 protocol, although it could be made to work on other network protocols
169 with only minor changes. However, it is recommended that TCP/IP
170 protocol is used under SILC protocol. Typical implementation would
171 be made in client-server model.
177 This section describes various SILC protocol concepts that forms the
178 actual protocol, and in the end, the actual SILC network. The mission
179 of the protocol is to deliver messages from clients to other clients
180 through routers and servers in secure manner. The messages may also
181 be delivered from one client to many clients forming a group, also
184 This section does not focus to security issues, instead basic network
185 concepts are introduced to make the topology of the SILC network
190 2.1 SILC Network Topology
192 SILC network is a cellular network as opposed to tree style network
193 topology. The rationale for this is to have servers that can perform
194 specific kind of tasks what other servers cannot perform. This leads
195 to two kinds of servers; normal SILC servers and SILC routers.
197 A difference between normal server and router server is that routers
198 knows everything about everything in the network. They also do the
199 actual routing of the messages to the correct receiver. Normal servers
200 knows only about local information and nothing about global information.
201 This makes the network faster as there are less servers that needs to
202 keep global information up to date at all time.
204 This, on the other hand, leads to cellular like network, where routers
205 are in the centrum on the cell and servers are connected to the router.
207 Following diagram represents SILC network topology.
227 ---- ---- ---- ---- ---- ----
228 | S8 | S5 | S4 | | S7 | S5 | S6 |
229 ----- ---- ----- ----- ---- -----
230 | S7 | S/R1 | S2 | --- | S8 | S/R2 | S4 |
231 ---- ------ ---- ---- ------ ----
232 | S6 | S3 | S1 | | S1 | S3 | S2 | ---- ----
233 ---- ---- ---- ---- ---- ---- | S3 | S1 |
234 Cell 1. \\ Cell 2. | \\____ ----- -----
236 ---- ---- ---- ---- ---- ---- ---- ------
237 | S7 | S4 | S2 | | S1 | S3 | S2 | | S2 | S5 |
238 ----- ---- ----- ----- ---- ----- ---- ----
239 | S6 | S/R3 | S1 | --- | S4 | S/R5 | S5 | ____/ Cell 4.
240 ---- ------ ---- ---- ------ ----
241 | S8 | S5 | S3 | | S6 | S7 | S8 | ... etc ...
242 ---- ---- ---- ---- ---- ----
247 Figure 1: SILC Network Topology
250 A cell is formed when a server or servers connect to one router. In
251 SILC network normal server cannot directly connect to other normal
252 server. Normal server may only connect to SILC router which then
253 routes the messages to the other servers in the cell. Router servers
254 on the other hand may connect to other routers to form the actual SILC
255 network, as seen in above figure. However, router is also normal SILC
256 server; clients may connect to it the same way as to normal SILC
257 servers. Normal server also cannot have active connections to more
258 than one router. Normal server cannot be connected to two different
259 cells. Router servers, on the other hand, may have as many router to
260 router connections as needed.
262 There are many issues in this network topology that needs to be careful
263 about. Issues like the size of the cells, the number of the routers in
264 the SILC network and the capacity requirements of the routers. These
265 issues should be discussed in the Internet Community and additional
266 documents on the issue will be written.
270 2.2 Communication Inside a Cell
272 It is always guaranteed that inside a cell message is delivered to the
273 recipient with at most two server hops. Client who is connected to
274 server in the cell and is talking on channel to other client connected
275 to other server in the same cell, will have its messages delivered from
276 its local server first to the router of the cell, and from the router
277 to the other server in the cell. Following diagram represents this
292 Figure 2: Communication Inside cell
295 Example: Client 1. connected to Server 1. message sent to
296 Client 4. connected to Server 2. travels from Server 1.
297 first to Router which routes the message to Server 2.
298 which then sends it to the Client 4. All the other
299 servers in the cell will not see the routed message.
302 If client is connected directly to the router, as router is also normal
303 SILC server, the messages inside the cell are always delivered only with
304 one server hop. If clients communicating with each other are connected
305 to the same server, no router interaction is needed. This is the optimal
306 situation of message delivery in the SILC network.
310 2.3 Communication in the Network
312 If the message is destined to server that does not belong to local cell
313 the message is routed to the router server to which the destination
314 server belongs, if the local router is connected to destination router.
315 If there is no direct connection to the destination router, the local
316 router routes the message to its primary route. Following diagram
317 represents message sending between cells.
322 1 --- S1 S4 --- 5 S2 --- 1
323 S/R - - - - - - - - S/R
333 Figure 3: Communication Between Cells
336 Example: Client 5. connected to Server 4. in Cell 1. message sent
337 to Client 2. connected to Server 1. in Cell 2. travels
338 from Server 4. to Router which routes the message to
339 Router in Cell 2, which then routes the message to
340 Server 1. All the other servers and routers in the
341 network will not see the routed message.
344 The optimal case of message delivery from client point of view is
345 when clients are connected directly to the routers and the messages
346 are delivered from one router to the other router.
350 2.4 Channel Communication
352 Messages may be sent to group of clients as well. Sending messages to
353 many clients works the same way as sending messages point to point, from
354 message delivery point of view. Security issues are another matter
355 which are not discussed in this section.
357 Router server handles the message routing to multiple recipients. If
358 any recipient is not in the same cell as the sender the messages are
361 Server distributes the channel message to its local clients who are
362 joined to the channel. Also, router distributes the message to its
363 local clients on the channel.
367 3. SILC Specification
369 This section describes the SILC protocol. However, [SILC2] and
370 [SILC3] describes other important protocols that are part of this SILC
371 specification and must be read.
377 A client is a piece of software connecting to SILC server. SILC client
378 cannot be SILC server. Purpose of clients is to provide the user
379 interface of the SILC services for end user. Clients are distinguished
380 from other clients by unique Client ID. Client ID is a 128 bit ID that
381 is used in the communication in the SILC network. The client ID is
382 based on the nickname selected by the user. User uses logical nicknames
383 in communication which are then mapped to the corresponding Client ID.
384 Client ID's are low level identifications and must not be seen by the
387 Clients provide other information about the end user as well. Information
388 such as the nickname of the user, username and the hostname of the end
389 user and user's real name. See section 3.2 Server for information of
390 the requirements of keeping this information.
392 The nickname selected by the user is not unique in the SILC network.
393 There can be 2^8 same nicknames for one IP address. As for comparison to
394 IRC [IRC] where nicknames are unique this is a fundamental difference
395 between SILC and IRC. This causes the server names to be used along
396 with the nicknames to identify specific users when sending messages.
397 This feature of SILC makes IRC style nickname-wars obsolete as no one
398 owns their nickname; there can always be someone else with the same
399 nickname. Another difference is that there are no limit of the length
400 of the nickname in the SILC.
406 Client ID is used to identify users in the SILC network. The Client ID
407 is unique to the extent that there can be 2^128 different Client ID's.
408 Collisions are not expected to happen. The Client ID is defined as
412 128 bit Client ID based on IPv4 addresses:
414 32 bit ServerID IP address (bits 1-32)
416 88 bit Truncated MD5 hash value of the nickname
418 o Server ID IP address - Indicates the server where this
419 client is coming from. The IP address hence equals the
420 server IP address where to the client has connected.
422 o Random number - Random number to further randomize the
423 Client ID. This makes it possible to have 2^8 same
424 nicknames from the same server IP address.
426 o MD5 hash - MD5 hash value of the nickname is truncated
427 taking 88 bits from the start of the hash value. This
428 hash value is used to search the user's Client ID from
432 Collisions could occur when more than 2^8 clients using same nickname
433 from the same server IP address is connected to the SILC network.
434 Server must be able to handle this situation by refusing to accept
435 anymore of that nickname.
437 Another possible collision may happen with the truncated hash value of
438 the nickname. It could be possible to have same truncated hash value for
439 two different nicknames. However, this is not expected to happen nor
440 cause any problems if it would occur. Nicknames are usually logical and
441 it is unlikely to have two distinct logical nicknames produce same
442 truncated hash value.
448 Servers are the most important parts of the SILC network. They form the
449 basis of the SILC, providing a point to which clients may connect to.
450 There are two kinds of servers in SILC; normal servers and router servers.
451 This section focuses on the normal server and router server is described
452 in the section 3.3 Router.
454 Normal servers may not directly connect to other normal server. Normal
455 servers may only directly connect to router server. If the message sent
456 by the client is destined outside the local server it is always sent to
457 the router server for further routing. Server may only have one active
458 connection to router on same port. Normal server may not connect to other
459 cell's router except in situations where its cell's router is unavailable.
461 Servers and routers in the SILC network are considered to be trusted.
462 With out a doubt, servers that are set to work on ports above 1023 are
463 not considered to be trusted. Also, the service provider acts important
464 role in the server's trustworthy.
468 3.2.1 Server's Local ID List
470 Normal server keeps various information about the clients and their end
471 users connected to it. Every normal server must keep list of all locally
472 connected clients, Client ID's, nicknames, usernames and hostnames and
473 user's real name. Normal servers only keeps local information and it
474 does not keep any global information. Hence, normal servers knows only
475 about their locally connected clients. This makes servers efficient as
476 they don't have to worry about global clients. Server is also responsible
477 of creating the Client ID's for their clients.
479 Normal server also keeps information about locally created channels and
489 Hence, local list for normal server includes:
492 server list - Router connection
500 client list - All clients in server
508 channel list - All channels in server
511 o Client ID's on channel
512 o Client ID modes on channel
521 Servers are distinguished from other servers by unique 64 bit Server ID.
522 The Server ID is used in the SILC to route messages to correct servers.
523 Server ID's also provide information for Client ID's, see section 3.1.1
524 Client ID. Server ID is defined as follows.
527 64 bit Server ID based on IPv4 addresses:
529 32 bit IP address of the server
533 o IP address of the server - This is the real IP address of
536 o Port - This is the port the server is binded to.
538 o Random number - This is used to further randomize the Server ID.
541 Collisions are not expected to happen in any conditions. The Server ID
542 is always created by the server itself and server is resposible of
543 distributing it to the router.
547 3.2.3 SILC Server Ports
549 Following ports has been assigned by IANA for the SILC protocol:
556 If there are needs to create new SILC networks in the future the port
557 numbers must be officially assigned by the IANA.
559 Server on network above privileged ports (>1023) should not be trusted
560 as they could have been set up by untrusted party.
566 Router server in SILC network is responsible for keeping the cell together
567 and routing messages to other servers and to other routers. Router server
568 is also a normal server thus clients may connect to it as it would be
569 just normal SILC server.
571 However, router servers has a lot of important tasks that normal servers
572 do not have. Router server knows everything about everything in the SILC.
573 They know all clients currently on SILC, all servers and routers and all
574 channels in SILC. Routers are the only servers in SILC that care about
575 global information and keeping them up to date at all time. And, this
576 is what they must do.
580 3.3.1 Router's Local ID List
582 Router server as well must keep local list of connected clients and
583 locally created channels. However, this list is extended to include all
584 the informations of the entire cell, not just the server itself as for
587 However, on router this list is a lot smaller since routers do not keep
588 information about user's nickname, username and hostname and real name
589 since these are not needed by the router. Router keeps only information
596 Hence, local list for router includes:
599 server list - All servers in the cell
606 client list - All clients in the cell
609 channel list - All channels in the cell
611 o Client ID's on channel
612 o Client ID modes on channel
617 Note that locally connected clients and other information include all the
618 same information as defined in section section 3.2.1 Server's Local ID
623 3.3.2 Router's Global ID List
625 Router server must also keep global list. Normal servers do not have
626 global list as they know only about local information. Global list
627 includes all the clients on SILC, their Client ID's, all created channels
628 and their Channel ID's and all servers and routers on SILC and their
629 Server ID's. That is said, global list is for global information and the
630 list must not include the local information already on the router's local
633 Note that the global list does not include information like nicknames,
634 usernames and hostnames or user's real names. Router does not keep
635 these informations as they are not needed by the router. This
636 information is available from the client's server which maybe queried
639 Hence, global list includes:
642 server list - All servers in SILC
648 client list - All clients in SILC
651 channel list - All channels in SILC
653 o Client ID's on channel
654 o Client ID modes on channel
659 3.3.3 Router's Server ID
661 Router's Server ID's are equivalent to normal Server ID's. As routers
662 are normal servers as well same types of ID's applies for routers as well.
663 Thus, see section 3.2.2 Server ID. Server ID's for routers are always
664 created by the remote router where the router is connected to.
670 A channel is a named group of one or more clients which will all receive
671 messages addressed to that channel. The channel is created when first
672 client requests JOIN command to the channel, and the channel ceases to
673 exist when the last client leaves it. When channel exists, any client
674 can reference it using the name of the channel.
676 Channel names are unique although the real uniqueness comes from 64 bit
677 Channel ID that unifies each channel. However, channel names are still
678 unique and no two global channels with same name may exist. Channel name
679 is a string which begins with `#' character. There is no limit on the
680 length of the channel name. Channel names may not contain any spaces
681 (` '), any non-printable ASCII characters, commas (`,') and wildcard
684 Channels can have operators that can administrate the channel and
685 operate all of its modes. Following operators on channel exist on SILC
689 o Channel founder - When channel is created the joining client becomes
690 channel founder. Channel founder is channel operator with some more
691 privileges. Basically, channel founder can fully operate the channel
692 and all of its modes. The privileges are limited only to the particular
693 channel. There can be only one channel founder per channel. Channel
694 founder supersedes channel operator's privileges.
696 Channel founder privileges cannot be removed by any other operator on
697 channel. When channel founder leaves the channel there is no channel
698 founder on the channel. Channel founder also cannot be removed by
699 force from the channel.
701 o Channel operator - When client joins to channel that has not existed
702 previously it will become automatically channel operator (and channel
703 founder discussed above). Channel operator is able administrate the
704 channel, set some modes on channel, remove a badly behaving client from
705 the channel and promote other clients to become channel operator.
706 The privileges are limited only to the particular channel.
708 Normal channel user may be promoted (opped) to channel operator
709 gaining channel operator privileges. Channel founder or other channel
710 operator may also demote (deop) channel operator to normal channel
718 Channels are distinguished from other channels by unique Channel ID.
719 The Channel ID is a 64 bit ID and collisions are not expected to happen
720 in any conditions. Channel names are just for logical use of channels.
721 The Channel ID is created by the server where the channel is created.
722 The Channel ID is defined as follows.
725 64 bit Channel ID based on IPv4 addresses:
727 32 bit Router's Server ID IP address (bits 1-32)
728 16 bit Router's Server ID port (bits 33-48)
731 o Router's Server ID IP address - Indicates the IP address of
732 the router of the cell where this channel is created. This is
733 taken from the router's Server ID. This way SILC router knows
734 where this channel resides in the SILC network.
736 o Router's Server ID port - Indicates the port of the channel on
737 the server. This is taken from the router's Server ID.
739 o Random number - To further randomize the Channel ID. This makes
740 sure that there are no collisions. This also means that
741 in a cell there can be 2^16 channels.
748 Operators are normal users with extra privileges to their server or
749 router. Usually these people are SILC server and router administrators
750 that take care of their own server and clients on them. The purpose of
751 operators is to administrate the SILC server or router. However, even
752 an operator with highest privileges is not able to enter invite-only
753 channel, to gain access to the contents of a encrypted and authenticated
754 packets traveling in the SILC network or to gain channel operator
755 privileges on public channels without being promoted. They have the
756 same privileges as everyone else except they are able to administrate
757 their server or router.
763 Commands are very important part on SILC network especially for client
764 which uses commands to operate on the SILC network. Commands are used
765 to set nickname, join to channel, change modes and many other things.
767 Client usually sends the commands and server replies by sending a reply
768 packet to the command. Server may also send commands usually to serve
769 the original client's request. However, server may not send command
770 to client and there are some commands that server must not send. Server
771 is also able to send the forwarded command packets. For example,
772 SILC_COMMAND_JOIN is always forwarded packet. See [SILC2] for more
773 about packet forwarding.
775 Note that the command reply is usually sent only after client has sent
776 the command request but server is allowed to send command reply packet
777 to client even if client has not requested the command. Client may,
778 however, choose not to accept the command reply, but there are some
779 command replies that the client should accept. Example of a such
780 command reply is reply to SILC_COMMAND_CMODE command that the server
781 uses to distribute the channel mode on all clients on the channel
782 when the mode has changed.
784 It is expected that some of the commands may be miss-used by clients
785 resulting various problems on the server side. Every implementation
786 should assure that commands may not be executed more than once, say,
787 in two (2) seconds. This should be sufficient to prevent the miss-use
790 SILC commands are described in section 5 SILC Commands.
796 Packets are naturally the most important part of the protocol and the
797 packets are what actually makes the protocol. Packets in SILC network
798 are always encrypted using, usually, the shared secret session key
799 or some other key, for example, channel key, when encrypting channel
800 messages. The SILC Packet Protocol is a wide protocol and is described
801 in [SILC2]. This document does not define or describe details of
808 3.8 Packet Encryption
810 All packets passed in SILC network must be encrypted. This section
811 defines how packets must be encrypted in the SILC network. The detailed
812 description of the actual encryption process of the packets are
813 described in [SILC2].
815 Client and its server shares secret symmetric session key which is
816 established by the SILC Key Exchange Protocol, described in [SILC3].
817 Every packet sent from client to server, with exception of packets for
818 channels, are encrypted with this session key.
820 Channels has their own key that are shared by every client on the channel.
821 However, the channel keys are cell specific thus one cell does not know
822 the channel key of the other cell, even if that key is for same channel.
823 Channel key is also known by the routers and all servers that has clients
824 on the channel. However, channels may have channel private keys that
825 are entirely local setting for client. All clients on the channel must
826 know the channel private key before hand to be able to talk on the
827 channel. In this case, no server or router knows the key for channel.
829 Server shares secret symmetric session key with router which is
830 established by the SILC Key Exchange Protocol. Every packet passed from
831 server to router, with exception of packets for channels, are encrypted
832 with the shared session key. Same way, router server shares secret
833 symmetric key with its primary route. However, every packet passed
834 from router to other router, including packets for channels, are
835 encrypted with the shared session key. Every router connection has
836 their own session keys.
840 3.8.1 Determination of the Source and the Destination
842 The source and the destination of the packet needs to be determined
843 to be able to route the packets to correct receiver. This information
844 is available in the SILC Packet Header which is included in all packets
845 sent in SILC network. The SILC Packet Header is described in [SILC2].
847 The header is always encrypted with the session key who is next receiver
848 of the packet along the route. The receiver of the packet, for example
849 a router along the route, is able to determine the sender and the
850 destination of the packet by decrypting the SILC Packet Header and
851 checking the ID's attached to the header. The ID's in the header will
852 tell to where the packet needs to be sent and where it is coming from.
854 The header in the packet does not change during the routing of the
855 packet. The original sender, for example client, assembles the packet
856 and the packet header and server or router between the sender and the
857 receiver must not change the packet header.
859 Note that the packet and the packet header may be encrypted with
860 different keys. For example, packets to channels are encrypted with
861 the channel key, however, the header is encrypted with the session key
862 as described above. However, the header and the packet may be encrypted
863 with same key. This is case, for example, with command packets.
867 3.8.2 Client To Client
869 Process of message delivery and encryption from client to another
870 client is as follows.
872 Example: Private message from client to another client on different
873 servers. Clients do not share private message delivery
874 keys; normal session keys are used.
876 o Client 1. sends encrypted packet to its server. The packet is
877 encrypted with the session key shared between client and its
880 o Server determines the destination of the packet and decrypts
881 the packet. Server encrypts the packet with session key shared
882 between the server and its router, and sends the packet to the
885 o Router determines the destination of the packet and decrypts
886 the packet. Router encrypts the packet with session key
887 shared between the router and the destination server, and sends
888 the packet to the server.
890 o Server determines the client to which the packet is destined
891 to and decrypts the packet. Server encrypts the packet with
892 session key shared between the server and the destination client,
893 and sends the packet to the client.
895 o Client 2. decrypts the packet.
898 Example: Private message from client to another client on different
899 servers. Clients has established secret shared private
900 message delivery key with each other and that is used in
901 the message encryption.
903 o Client 1. sends encrypted packet to its server. The packet is
904 encrypted with the private message delivery key shared between
907 o Server determines the destination of the packet and sends the
908 packet to the router.
910 o Router determines the destination of the packet and sends the
911 packet to the server.
913 o Server determines the client to which the packet is destined
914 to and sends the packet to the client.
916 o Client 2. decrypts the packet with the secret shared key.
919 If clients share secret key with each other the private message
920 delivery is much simpler since servers and routers between the
921 clients do not need to decrypt and re-encrypt the packet.
923 The process for clients on same server is much simpler as there are
924 no need to send the packet to the router. The process for clients
925 on different cells is same as above except that the packet is routed
926 outside the cell. The router of the destination cell routes the
927 packet to the destination same way as described above.
931 3.8.3 Client To Channel
933 Process of message delivery from client on channel to all the clients
936 Example: Channel of four users; two on same server, other two on
937 different cells. Client sends message to the channel.
939 o Client 1. encrypts the packet with channel key and sends the
940 packet to its server.
942 o Server determines local clients on the channel and sends the
943 packet to the Client on the same server. Server then sends
944 the packet to its router for further routing.
946 o Router determines local clients on the channel, if found
947 sends packet to the local clients. Router determines global
948 clients on the channel and sends the packet to its primary
949 router or fastest route.
951 o (Other router(s) do the same thing and sends the packet to
954 o Server determines local clients on the channel and sends the
955 packet to the client.
957 o All clients receiving the packet decrypts the packet.
961 3.8.4 Server To Server
963 Server to server packet delivery and encryption is described in above
964 examples. Router to router packet delivery is analogous to server to
965 server. However, some packets, such as channel packets, are processed
966 differently. These cases are described later in this document and
967 more in detail in [SILC2].
971 3.9 Key Exchange And Authentication
973 Key exchange is done always when for example client connects to server
974 but also when server and router and router and router connects to each
975 other. The purpose of key exchange protocol is to provide secure key
976 material to be used in the communication. The key material is used to
977 derive various security parameters used to secure SILC packets. The
978 SILC Key Exchange protocol is described in detail in [SILC3].
980 Authentication is done after key exchange protocol has been successfully
981 completed. The purpose of authentication is to authenticate for example
982 client connecting to the server. However, Usually clients are accepted
983 to connect to server without explicit authentication. Servers are
984 required use authentication protocol when connecting. The authentication
985 may be based on passphrase (pre-shared-secret) or public key. The
986 connection authentication protocol is described in detail in [SILC3].
992 This section defines all the allowed algorithms that can be used in
993 the SILC protocol. This includes mandatory cipher, mandatory public
994 key algorithm and MAC algorithms.
1000 Cipher is the encryption algorithm that is used to protect the data
1001 in the SILC packets. See [SILC2] of the actual encryption process and
1002 definition of how it must be done. SILC has a mandatory algorithm that
1003 must be supported in order to be compliant with this protocol.
1010 Following ciphers are defined in SILC protocol:
1013 blowfish-cbc Blowfish in CBC mode (mandatory)
1014 twofish-cbc Twofish in CBC mode (optional)
1015 rc6-cbc RC6 in CBC mode (optional)
1016 rc5-cbc RC5 in CBC mode (optional)
1017 mars-cbc Mars in CBC mode (optional)
1018 none No encryption (optional)
1022 All algorithms must use minimum of 128 bit key, by default. Several
1023 algorithms, however, supports longer keys and it is recommended to use
1024 longer keys if they are available.
1026 Algorithm none does not perform any encryption process at all and
1027 thus is not recommended to be used. It is recommended that no client
1028 or server implementation would accept none algorithms except in special
1031 Additional ciphers may be defined to be used in SILC by using the
1032 same name format as above.
1036 3.10.2 Public Key Algorithms
1038 Public keys are used in SILC to authenticate entities in SILC network
1039 and to perform other tasks related to public key cryptography. The
1040 public keys are also used in the SILC Key Exchange protocol [SILC3].
1042 Following public key algorithms are defined in SILC protocol:
1049 Both of the algorithms are described in [Scheneir] and [Menezes].
1051 Additional public key algorithms may be defined to be used in SILC.
1055 3.10.3 MAC Algorithms
1057 Data integrity is protected by computing a message authentication code
1058 (MAC) of the packet data. See [SILC2] for details how to compute the
1065 Following MAC algorithms are defined in SILC protocol:
1068 hmac-sha1 HMAC-SHA1, length = 20 (mandatory)
1069 hmac-md5 HMAC-MD5, length = 16 (optional)
1070 none No MAC (optional)
1073 The none MAC is not recommended to be used as the packet is not
1074 authenticated when MAC is not computed. It is recommended that no
1075 client or server would accept none MAC except in special debugging
1078 The HMAC algorithm is described in [HMAC] and hash algorithms that
1079 are used as part of the HMACs are described in [Scheneir] and in
1082 Additional MAC algorithms may be defined to be used in SILC.
1086 3.10.4 Compression Algorithms
1088 SILC protocol supports compression that may be applied to unencrypted
1089 data. It is recommended to use compression on slow links as it may
1090 significantly speed up the data transmission. By default, SILC does not
1091 use compression which is the mode that must be supported by all SILC
1094 Following compression algorithms are defined:
1097 none No compression (mandatory)
1098 zlib GBU ZLIB (LZ77) compression (optional)
1101 Additional compression algorithms may be defined to be used in SILC.
1105 3.11 SILC Public Key
1107 This section defines the type and format of the SILC public key. All
1108 implementations must support this public key type. See [SILC3] for
1109 other optional public key and certificate types allowed in SILC
1110 protocol. Public keys in SILC may be used to authenticate entities
1111 and to perform other tasks related to public key cryptography.
1113 The format of the SILC Public Key is as follows:
1124 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
1125 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1126 | Public Key Length |
1127 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1128 | Algorithm Name Length | |
1129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1134 | Identifier Length | |
1135 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1139 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1143 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1147 Figure 4: SILC Public Key
1151 o Public Key Length (4 bytes) - Indicates the full length
1152 of the public key, not including this field.
1154 o Algorithm Name Length (2 bytes) - Indicates the length
1155 of the Algorithm Length field, not including this field.
1157 o Algorithm name (variable length) - Indicates the name
1158 of the public key algorithm that the key is. See the
1159 section 3.10.2 Public Key Algorithms for defined names.
1161 o Identifier Length (2 bytes) - Indicates the length of
1162 the Identifier field, not including this field.
1164 o Identifier (variable length) - Indicates the identifier
1165 of the public key. This data can be used to identify
1166 the owner of the key. The identifier is of following
1170 HN Host name or IP address
1177 Examples of an identifier:
1179 `UN=priikone, HN=poseidon.pspt.fi, E=priikone@poseidon.pspt.fi'
1181 `UN=sam, HN=dummy.fi, RN=Sammy Sam, O=Company XYZ, C=Finland'
1183 At least user name (UN) and host name (HN) must be provided as
1184 identifier. The fields are separated by commas (`,'). If
1185 comma is in the identifier string it must be written as `\\,',
1186 for example, `O=Company XYZ\\, Inc.'.
1188 o Public Data (variable length) - Includes the actual
1189 public data of the public key.
1191 The format of this field for RSA algorithm is
1200 The format of this field for DSS algorithm is
1212 The variable length fields are multiple precession
1213 integers encoded as strings in both examples.
1215 Other algorithms must define their own type of this
1216 field if they are used.
1219 All fields in the public key are in MSB (most significant byte first)
1224 3.12 SILC Version Detection
1226 The version detection of both client and server is performed at the
1227 connection phase while executing the SILC Key Exchange protocol. The
1228 version identifier is exchanged between intiator and responder. The
1229 version identifier is of following format:
1232 SILC-<protocol version>-<software version>
1235 The version strings are of following format:
1238 protocol version = <major>.<minor>
1239 software version = <major>[.<minor>[.<build>]]
1242 Protocol version may provide both major and minor version. Currently
1243 implementations must set the protocol version and accept the protocol
1244 version as SILC-1.0-<sotware version>.
1246 Software version may provide major, minor and build version. The
1247 software version may be freely set and accepted.
1249 Thus, the version string could be, for example:
1259 This section describes various SILC procedures such as how the
1260 connections are created and registered, how channels are created and
1261 so on. The section describes the procedures only generally as details
1262 are described in [SILC2] and [SILC3].
1266 4.1 Creating Client Connection
1268 This section descibres the procedure when client connects to SILC server.
1269 When client connects to server the server must perform IP address lookup
1270 and reverse IP address lookup to assure that the origin host really is
1271 who it claims to be. Client, host, connecting to server must have
1272 both valid IP address and fully qualified domain name (FQDN).
1274 After that client and server performs SILC Key Exchange protocol which
1275 will provide the key material used later in the communication. The
1276 key exchange protocol must be completed successfully before the connection
1277 registration may continue. The SILC Key Exchange protocol is described
1280 Typical server implementation would keep a list of connections that it
1281 allows to connect to the server. The implementation would check, for
1282 example, the connecting client's IP address from the connection list
1283 before the SILC Key Exchange protocol has been started. Reason for
1284 this is that if the host is not allowed to connect to the server there
1285 is no reason to perform a key exchange protocol.
1287 After successful key exchange protocol the client and server performs
1288 connection authentication protocol. The purpose of the protocol is to
1289 authenticate the client connecting to the server. Flexible
1290 implementation could also accept the client to connect to the server
1291 without explicit authentication. However, if authentication is
1292 desired for a specific client it may be based on passphrase or
1293 public key authentication. If authentication fails the connection
1294 must be terminated. The connection authentication protocol is described
1297 After successful key exchange and authentication protocol the client
1298 registers itself by sending SILC_PACKET_NEW_CLIENT packet to the
1299 server. This packet includes various information about the client
1300 that the server uses to create the client. Server creates the client
1301 and sends SILC_PACKET_NEW_ID to the client which includes the created
1302 Client ID that the client must start using after that. After that
1303 all SILC packets from the client must have the Client ID as the
1304 Source ID in the SILC Packet Header, described in [SILC2].
1306 Client must also get the server's Server ID that is to be used as
1307 Destination ID in the SILC Packet Header when communicating with
1308 the server (for example when sending commands to the server). The
1309 ID may be resolved in two ways. Client can take the ID from an
1310 previously received packet from server that must include the ID,
1311 or to send SILC_COMMAND_INFO command and receive the Server ID as
1314 Server may choose not to use the information received in the
1315 SILC_PACKET_NEW_CLIENT packet. For example, if public key or
1316 certificate were used in the authentication, server may use those
1317 informations rather than what it received from client. This is suitable
1318 way to get the true information about client if it is available.
1320 The nickname of client is initially set to the username sent in the
1321 SILC_PACKET_NEW_CLIENT packet. User should set the nickname to more
1322 suitable by sending SILC_COMMAND_NICK command. However, this is not
1323 required as part of registration process.
1325 Server must also distribute the information about newly registered
1326 client to its router (or if the server is router, to all routers in
1327 the SILC network). More information about this in [SILC2].
1331 4.2 Creating Server Connection
1333 This section descibres the procedure when server connects to its
1334 router (or when router connects to other router, the cases are
1335 equivalent). The procedure is very much alike when client connects
1336 to the server thus it is not repeated here.
1338 One difference is that server must perform connection authentication
1339 protocol with proper authentication. Proper authentication is based
1340 on passphrase or public key authentication.
1342 After server and router has successfully performed the key exchange
1343 and connection authentication protocol, the server register itself
1344 to the router by sending SILC_PACKET_NEW_SERVER packet. This packet
1345 includes the server's Server ID that it has created by itself and
1346 other relevant information about the server.
1348 After router has received the SILC_PACKET_NEW_SERVER packet it
1349 distributes the information about newly registered server to all routers
1350 in the SILC network. More information about this in [SILC2].
1352 As client needed to resolve the destination ID this must be done by the
1353 server that connected to the router, as well. The way to resolve it is
1354 to get the ID from previously received packet. Server must also start
1355 using its own Server ID as Source ID in SILC Packet Header and the
1356 router's Server ID as Destination when communicating with the router.
1358 If the server has already connected clients and locally created
1359 channels the server must distribute these informations to the router.
1360 The distribution is done by sending packet SILC_PACKET_NEW_CHANNEL.
1361 See [SILC2] for more information on this.
1365 4.3 Joining to a Channel
1367 This section describes the procedure when client joins to a channel.
1368 Client may join to channel by sending command SILC_COMMAND_JOIN to the
1369 server. If the receiver receiving join command is normal server the
1370 server must check its local list whether this channel already exists
1371 locally. This would indicate that some client connected to the server
1372 has already joined to the channel. If this is case the client is
1373 joined to the client, new channel key is created and information about
1374 newly joined channel is sent to the router. The new channel key is
1375 also distributed to the router and to all clients on the channel.
1377 If the channel does not exist in the local list the command must be
1378 fowarded to the router which will then perform the actual joining
1379 procedure. When server receives the reply to the command from the
1380 router it must be distributed to the client who sent the command
1381 originally. Server will also receive the channel key from the server
1382 that it must distribute to the client who originally requested the
1383 join command. The server must also save the channel key.
1385 If the receiver of the join command is router it must first check its
1386 local list whether anyone in the cell has already joined to the channel.
1387 If this is the case the client is joined to the channel and reply is
1388 sent to the client. If the command was sent by server the command reply
1389 is sent to the server who sent it. Then the router must also create
1390 new channel key and distribute it to all clients on the channel and
1391 all servers that has clients on the channel.
1393 If the channel does not exist on the router's local list it must
1394 check the global list whether the channel exists at all. If it does
1395 the client is joined to the channel as described previously. If
1396 the channel does not exist the channel is created and the client
1397 is joined to the channel. The channel key is also created and
1398 distributed as previously described. The client joining to the created
1399 channel is made automatically channel founder and both channel founder
1400 and channel operator privileges is set for the client.
1402 When the router joins the client to the channel it must send
1403 information about newly joined client to all routers in the SILC
1404 network. Also, if the channel was created in the process, information
1405 about newly created channel must also be distributed to all routers.
1406 The distribution of newly created channel is done by sending packet
1407 SILC_PACKET_NEW_CHANNEL.
1409 It is important to note that new channel key is created always when
1410 new client joins to channel, whether the channel has existed previously
1411 or not. This way the new client on the channel is not able to decrypt
1412 any of the old traffic on the channel.
1414 Client who receives the reply to the join command must start using
1415 the received Channel ID in the channel message communication thereafter.
1416 However, client must not start communicating on the channel before
1417 it has received the packet SILC_PACKET_CHANNEL_KEY.
1419 If client wants to know the other clients currently on the channel
1420 the client must send SILC_COMMAND_NAMES command to receive a list of
1421 channel users. Server implementation, however, may send command reply
1422 packet to SILC_COMMAND_NAMES command after client has joined to the
1423 channel even if the client has not sent the command.
1427 4.4 Channel Key Generation
1429 Channel keys are created by router who creates the channel by taking
1430 enough randomness from cryptographically strong random number generator.
1431 The key is generated always when channel is created, when new client
1432 joins a channel and after the key has expired. Key could expire for
1435 The key must also be re-generated whenever some client leaves a channel.
1436 In this case the key is created from scratch by taking enough randomness
1437 from the random number generator. After that the key is distributed to
1438 all clients on the channel. However, channel keys are cell specific thus
1439 the key is created only on the cell where the client, who leaved the
1440 channel, exists. While the server or router is creating the new channel
1441 key, no other client may join to the channel. Messages that are sent
1442 while creating the new key are still processed with the old key. After
1443 server has sent the SILC_PACKET_CHANNEL_KEY packet must client start
1444 using the new key. If server creates the new key the server must also
1445 send the new key to its router. See [SILC2] on more information about
1446 how channel messages must be encrypted and decrypted when router is
1451 4.5 Private Message Sending and Reception
1453 Private messages are sent point to point. Client explicitly destines
1454 a private message to specific client that is delivered to only to that
1455 client. No other client may receive the private message. The receiver
1456 of the private message is destined in the SILC Packet Header as any
1457 other packet as well.
1459 If the sender of a private message does not know the receiver's Client
1460 ID, it must resolve it from server. There are two ways to resolve the
1461 client ID from server; it is recommended that client ipmlementations
1462 send SILC_COMMAND_IDENTIFY command to receive the Client ID. Client
1463 may also send SILC_COMMAND_WHOIS command to receive the Client ID.
1464 If the sender has received earlier a private message from the receiver
1465 it should have cached the Client ID from the SILC Packet Header.
1467 Receiver of a private message should not explicitly trust the nickname
1468 that it receives in the Private Message Payload, described in [SILC2].
1469 Implementations could resolve the nickname from server, as described
1470 previously, and compare the received Client ID and the SILC Packet
1471 Header's Client ID. The nickname in the payload is merely provided
1472 to be displayed for end user.
1474 See [SILC2] for describtion of private message encryption and decryption
1479 4.6 Private Message Key Generation
1481 Private message may be protected by key generated by client. The key
1482 may be generated and sent to the other client by sending packet
1483 SILC_PACKET_PRIVATE_MESSAGE_KEY which travels through the network
1484 and is secured by session keys. After that the private message key
1485 is used in the private message communication between those clients.
1486 See more information about how this works technically in [SILC2].
1488 Other choice is to entirely use keys that are not sent through
1489 the SILC network at all. This significantly adds security. This key
1490 would be pre-shared-key that is known by both of the clients. Both
1491 agree about using the key and starts sending packets that indicate
1492 that the private message is secured using private message key. This
1493 is the technical aspect mentioned previously that is described
1496 If the private message keys are not set to be used, which is the
1497 case by default in SILC, the private messages are secured by using
1498 normal session keys established by SILC Key Exchange protocol.
1504 4.7 Channel Message Sending and Reception
1506 Channel messages are delivered to group of users. The group forms a
1507 channel and all clients on the channel receives messages sent to the
1510 Channel messages are destined to channel by specifying the Channel ID
1511 as Destination ID in the SILC Packet Header. The server must then
1512 distribute the message to all clients on the channel by sending the
1513 channel message destined explicitly to a client on the channel.
1515 See [SILC2] for describtion of channel message encryption and decryption
1520 4.8 Session Key Regeneration
1522 Session keys should be regenerated peridiocally, say, once in an hour.
1523 The re-key process is started by sending SILC_PACKET_REKEY packet to
1524 other end, to indicate that re-key must be performed.
1526 If perfect forward secrecy (PFS) flag was selected in the SILC Key
1527 Exchange protocol [SILC3] the re-key must cause new key exchange with
1528 SKE protocol. In this case the protocol is secured with the old key
1529 and the protocol results to new key material. See [SILC3] for more
1530 information. After the SILC_PACKET_REKEY packet is sent the sender
1531 will perform the SKE protocol.
1533 If PFS flag was not set, which is the default case, then re-key is done
1534 without executing SKE protocol. In this case, the new key is created by
1535 hashing the old key with hash function selected earlier in the SKE
1536 protocol. If the digest length of the hash function is too short for the
1537 key, then the key is distributed as described in section Processing the
1538 Key Material in [SILC3]. After both parties has regenerated the session
1539 key, both send SILC_PACKET_REKEY_DONE packet to each other. These packets
1540 are still secured with the old key. After these packets, following
1541 packets must be protected with the new key.
1545 4.9 Command Sending and Reception
1547 Client usually sends the commands in the SILC network. In this case
1548 the client simply sends the command packet to server and the server
1549 processes it and replies with command reply packet.
1551 However, if the server is not able to process the command, it is usually
1552 sent to the server's router. This is case for example with commands such
1553 as, SILC_COMMAND_JOIN and SILC_COMMAND_WHOIS commands. However, there
1554 are other commands as well. For example, if client sends the WHOIS
1555 command requesting specific information about some client the server must
1556 send the WHOIS command to router so that all clients in SILC network
1557 are searched. The router, on the other hand, sends the WHOIS command
1558 to further to receive the exact information about the requested client.
1559 The WHOIS command travels all the way to the server who owns the client
1560 and it replies with command reply packet. Finally, the server who
1561 sent the command receives the command reply and it must be able to
1562 determine which client sent the original command. The server then
1563 sends command reply to the client. Implementations should have some
1564 kind of cache to handle, for example, WHOIS information. Servers
1565 and routers along the route could all cache the information for faster
1566 referencing in the future.
1568 The commands sent by server may be sent hop by hop until someone is able
1569 to process the command. However, it is preferred to destine the command
1570 as precisely as it is possible. In this case, other routers en route
1571 must route the command packet by checking the true sender and true
1572 destination of the packet. However, servers and routers must not route
1573 command reply packets to clients coming from other server. Client
1574 must not accept command reply packet originated from anyone else but
1575 from its own server.
1582 5.1 SILC Commands Syntax
1584 This section briefly describes the syntax of the command notions
1585 in this document. Every field in command is separated from each
1586 other by whitespaces (` ') indicating that each field is independent
1587 argument and each argument must have own Command Argument Payload.
1588 The number of maximum arguments are defined with each command
1589 separately. The Command Argument Payload is described in [SILC2].
1591 Every command defines specific number for each argument. Currently,
1592 they are defined in ascending order; first argument has number one
1593 (1), second has number two (2) and so on. This number is set into the
1594 Argument Type field in the Command Argument Payload. This makes it
1595 possible to send the arguments in free order as the number must be
1596 used to identify the type of the argument. This makes is it also
1597 possible to have multiple optional arguments in commands and in
1598 command replies. The number of argument is marked in parentheses
1599 before the actual argument.
1606 Example: Arguments: (1) <nickname> (2) <username@host>
1610 Every command replies with Status Payload. This payload tells the
1611 sender of the command whether the command was completed succefully or
1612 whether there was an error. If error occured the payload includes the
1613 error type. In the next section the Status Payload is not described
1614 as it is common to all commands and has been described here. Commands
1615 may reply with other arguments as well. These arguments are command
1616 specific and are described in the next section.
1625 Arguments: (1) <nickname>[@<server>] (2) <message>
1628 The command has maximum of 3 arguments. However, only first
1629 and second arguments are mandatory.
1631 First argument <nickname> is mandatory but may have optional
1632 <nickname@server> format as well. Second argument is mandatory
1633 <message> argument. Third argument is optional <count> argument.
1635 The numbers in parentheses are the argument specific numbers
1636 that specify the type of the argument in Command Argument Payload.
1637 The receiver always knows that, say, argument number two (2) is
1638 <message> argument, regardles of the ordering of the arguments in
1639 the Command Payload.
1641 Reply messages to the command:
1644 Arguments: (1) <Status Payload> (2) [<channel list>]
1645 (3) <idle time> (4) [<away message>]
1647 This command may reply with maximum of 4 arguments. However,
1648 only the first and third arguments are mandatory. The numbers
1649 in the parentheses have the same meaning as in the upper
1650 command sending specification.
1652 Every command reply with <Status Payload>, it is mandatory
1653 argument for all command replies and for this reason it is not
1654 described in the command reply descriptions.
1661 SILC_STATUS_ERR_TOO_MANY_TARGETS
1662 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1663 SILC_STATUS_ERR_NO_SUCH_NICK
1665 Every command reply also defines set of status message that it
1666 may return inside the <Status Payload>. All status messages
1667 are defined in the section 5.3 SILC Command Status Types.
1669 Every command that has some kind of ID as argument (for example
1670 <Client ID>) are actually ID Payloads, defined in [SILC2] that includes
1671 the type of the ID, length of the ID and the actual ID data. This
1672 way variable length ID's can be sent as arguments.
1677 5.2 SILC Commands List
1679 This section lists all SILC commands, however, it is expected that a
1680 implementation and especially client implementation has many more
1681 commands that has only local affect. These commands are official
1682 SILC commands that has both client and server sides and cannot be
1683 characterized as local commands.
1685 List of all defined commands in SILC follows.
1690 None. This is reserved command and must not be sent.
1693 1 SILC_COMMAND_WHOIS
1696 Arguments: (1) <nickname>[@<server>] (2) [<Client ID>]
1699 Whois command is used to query various information about specific
1700 user. The user maybe requested by their nickname and server name.
1701 The query may find multiple matching users as there are no unique
1702 nicknames in the SILC. The <count> option maybe given to narrow
1703 down the number of accepted results. If this is not defined there
1704 are no limit of accepted results. The query may also be narrowed
1705 down by defining the server name of the nickname.
1707 It is also possible to search the user by Client ID. If <Client ID>
1708 is provided server must use it as the search value instead of
1711 To prevent miss-use of this service wildcards in the nickname
1712 or in the servername are not permitted. It is not allowed
1713 to request all users on some server. The WHOIS requests must
1714 be based on specific nickname request.
1716 The WHOIS request must be always forwarded to router by server
1717 so that all users are searched. However, the server still must
1718 search its locally connected clients. The server must send
1719 this command to the server who owns the requested client. That
1720 server must reply to the command.
1722 Reply messages to the command:
1725 Arguments: (1) <Status Payload> (2) <Client ID>
1726 (3) <nickname>[@<server>] (4) <username@host>
1727 (5) <real name> (6) [<channel list>]
1730 This command may reply with several command reply messages to
1731 form a list of results. In this case the status payload will
1732 include STATUS_LIST_START status in the first reply and
1733 STATUS_LIST_END in the last reply to indicate the end of the
1734 list. If there are only one reply the status is set to normal
1737 The command replies include the Client ID of the nickname,
1738 nickname and servername, username and hostnamea and users real
1739 name. Client should process these replies only after the last
1740 reply has been received with the STATUS_LIST_END status. If the
1741 <count> option were defined in the query there will be only
1742 <count> many replies from the server.
1747 SILC_STATUS_LIST_START
1748 SILC_STATUS_LIST_END
1749 SILC_STATUS_ERR_NO_SUCH_NICK
1750 SILC_STATUS_ERR_WILDCARDS
1751 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1752 SILC_STATUS_ERR_TOO_MANY_PARAMS
1755 2 SILC_COMMAND_WHOWAS
1758 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1760 Whowas. This command is used to query history information about
1761 specific user. The user maybe requested by their nickname and
1762 server name. The query may find multiple matching users as there
1763 are no unique nicknames in the SILC. The <count> option maybe
1764 given to narrow down the number of accepted results. If this
1765 is not defined there are no limit of accepted results. The query
1766 may also be narrowed down by defining the server name of the
1769 To prevent miss-use of this service wildcards in the nickname
1770 or in the servername are not permitted. The WHOWAS requests must
1771 be based on specific nickname request.
1773 The WHOWAS request must be always forwarded to router by server
1774 so that all users are searched. However, the server still must
1775 search its locally connected clients.
1777 Reply messages to the command:
1780 Arguments: (1) <Status Payload> (2) <nickname>[@<server>]
1783 This command may reply with several command reply messages to form
1784 a list of results. In this case the status payload will include
1785 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1786 the last reply to indicate the end of the list. If there are only
1787 one reply the status is set to normal STATUS_OK.
1789 The command replies with nickname and username and hostname.
1790 Every server must keep history for some period of time of its
1791 locally connected clients.
1796 SILC_STATUS_LIST_START
1797 SILC_STATUS_LIST_END
1798 SILC_STATUS_ERR_NO_SUCH_NICK
1799 SILC_STATUS_ERR_WILDCARDS
1800 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1801 SILC_STATUS_ERR_TOO_MANY_PARAMS
1804 3 SILC_COMMAND_IDENTIFY
1807 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1809 Identify. Identify command is almost analogous to WHOIS command,
1810 except that it does not return as much information. Only relevant
1811 information such as Client ID is returned. This is usually used
1812 to get the Client ID of a client used in the communication with
1815 The query may find multiple matching users as there are no unique
1816 nicknames in the SILC. The <count> option maybe given to narrow
1817 down the number of accepted results. If this is not defined there
1818 are no limit of accepted results. The query may also be narrowed
1819 down by defining the server name of the nickname.
1821 To prevent miss-use of this service wildcards in the nickname
1822 or in the servername are not permitted. It is not allowed
1823 to request all users on some server. The IDENTIFY requests must
1824 be based on specific nickname request.
1826 Implementations may not want to give interface access to this
1827 command as it is hardly a command that would be used a end user.
1828 However, it must be implemented as it is used with private message
1831 The IDENTIFY must be always forwarded to router by server so that
1832 all users are searched. However, server must still search its
1833 locally connected clients.
1835 Reply messages to the command:
1838 Arguments: (1) <Status Payload> (2) <Client ID>
1839 (3) [<nickname>[@<server>]] (4) [<username@host>]
1841 This command may reply with several command reply messages to form
1842 a list of results. In this case the status payload will include
1843 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1844 the last reply to indicate the end of the list. If there are only
1845 one reply the status is set to normal STATUS_OK.
1847 The command replies with Client ID of the nickname and if more
1848 information is available it may reply with nickname and username
1849 and hostname. If the <count> option were defined in the query
1850 there will be only <count> many replies from the server.
1855 SILC_STATUS_LIST_START
1856 SILC_STATUS_LIST_END
1857 SILC_STATUS_ERR_NO_SUCH_NICK
1858 SILC_STATUS_ERR_WILDCARDS
1859 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1860 SILC_STATUS_ERR_TOO_MANY_PARAMS
1866 Arguments: (1) <nickname>
1868 Set/change nickname. This command is used to set nickname for
1869 user. There is no limit of the length of the nickname in SILC.
1870 Nickname must not include any spaces (` '), non-printable
1871 characters, commas (`,') and any wildcard characters. Note:
1872 nicknames in SILC are case-sensitive which must be taken into
1873 account when searching clients by nickname.
1875 Reply messages to the command:
1878 Arguments: (1) <Status Payload> (2) <New ID Payload>
1880 This command is replied always with New ID Payload that is
1881 generated by the server every time user changes their nickname.
1882 Client receiving this payload must start using the received
1883 Client ID as its current valid Client ID. The New ID Payload
1884 is described in [SILC2].
1889 SILC_STATUS_ERR_WILDCARDS
1890 SILC_STATUS_ERR_NICKNAME_IN_USE
1891 SILC_STATUS_ERR_BAD_NICKNAME
1892 SILC_STATUS_ERR_NOT_REGISTERED
1893 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1894 SILC_STATUS_ERR_TOO_MANY_PARAMS
1900 Arguments: (1) [<Channel ID>] [<server>]
1902 The list command is used to list channels and their topics on
1903 current server. If the <Channel ID> parameter is used, only the
1904 status of that channel is displayed. Secret channels are not
1905 listed at all. Private channels are listed with status indicating
1906 that the channel is private.
1908 If the <server> argument is specified the specified server's
1909 channels are listed. In this case the command must be sent to
1910 the server who owns the channel that was requested.
1912 Reply messages to the command:
1915 Arguments: (1) <Status Payload> (2) <Channel ID>
1916 (3) <channel> (4) <topic>
1918 This command may reply with several command reply messages to form
1919 a list of results. In this case the status payload will include
1920 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1921 the last reply to indicate the end of the list. If there are only
1922 one reply the status is set to normal STATUS_OK.
1924 This command replies with Channel ID, name and the topic of the
1925 channel. If the channel is private channel the <topic> includes
1931 SILC_STATUS_LIST_START
1932 SILC_STATUS_LIST_END
1933 SILC_STATUS_ERR_WILDCARDS
1934 SILC_STATUS_ERR_NOT_REGISTERED
1935 SILC_STATUS_ERR_TOO_MANY_PARAMS
1936 SILC_STATUS_ERR_NO_SUCH_CHANNEL
1937 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
1938 SILC_STATUS_ERR_NO_SUCH_SERVER
1941 6 SILC_COMMAND_TOPIC
1944 Arguments: (1) <Channel ID> (2) [<server>]]
1946 This command is used to change or view the topic of a channel.
1947 The topic for channel <Channel ID> is returned if there is no
1948 <topic> given. If the <topic> parameter is present, the topic
1949 for that channel will be changed, if the channel modes permit
1952 Reply messages to the command:
1955 Arguments: (1) <Status Payload> (2) [<topic>]
1957 The command may reply with the topic of the channel if it is
1963 SILC_STATUS_ERR_NOT_ON_CHANNEL
1964 SILC_STATUS_ERR_WILDCARDS
1965 SILC_STATUS_ERR_NOT_REGISTERED
1966 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1967 SILC_STATUS_ERR_NO_SUCH_CHANNEL
1968 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
1969 SILC_STATUS_ERR_NO_CHANNEL_ID
1970 SILC_STATUS_ERR_BAD_CHANNEL_ID
1971 SILC_STATUS_ERR_TOO_MANY_PARAMS
1972 SILC_STATUS_ERR_NO_CHANNEL_PRIV
1975 7 SILC_COMMAND_INVITE
1978 Arguments: (1) <Client ID> (2) <Channel ID>
1980 This command is used to invite other clients to join to the
1981 channel. The <Client ID> argument is the target client's ID that
1982 is being invited. The <Channel ID> is the Channel ID of the
1983 requested channel. The sender of this command must be on the
1984 channel. This command must fail if the requested channel does
1985 not exist, the requested client is already on the channel or if
1986 the channel is invite only channel and the caller of this command
1987 does not have at least channel operator privileges.
1989 Reply messages to the command:
1992 Arguments: (1) <Status Payload>
1994 This command replies only with Status Payload.
1999 SILC_STATUS_ERR_NOT_REGISTERED
2000 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2001 SILC_STATUS_ERR_TOO_MANY_PARAMS
2002 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2003 SILC_STATUS_ERR_NO_CLIENT_ID
2004 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2005 SILC_STATUS_ERR_NO_CHANNEL_ID
2006 SILC_STATUS_ERR_NOT_ON_CHANNEL
2007 SILC_STATUS_ERR_USER_ON_CHANNEL
2013 Arguments: (1) [<quit message>]
2015 This command is used by client to end SILC session. The server
2016 must close the connection to a client which sends this command.
2017 if <quit message> is given it will be sent to other clients on
2018 channel if the client is on channel when quitting.
2020 Reply messages to the command:
2022 This command does not reply anything.
2028 Arguments: (1) <Client ID> (2) [<comment>]
2030 This command is used by SILC operators to remove a client from
2031 SILC network. The removing has temporary effects and client may
2032 reconnect to SILC network. The <Client ID> is the client to be
2033 removed from SILC. The <comment> argument may be provided to
2034 give to the removed client some information why it was removed
2037 Reply messages to the command:
2040 Arguments: (1) <Status Payload>
2042 This command replies only with Status Payload.
2047 SILC_STATUS_ERR_WILDCARDS
2048 SILC_STATUS_ERR_NOT_REGISTERED
2049 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2050 SILC_STATUS_ERR_TOO_MANY_PARAMS
2051 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2052 SILC_STATUS_ERR_NO_CLIENT_ID
2058 10 SILC_COMMAND_INFO
2061 Arguments: (1) [<server>]
2063 This command is used to fetch various information about a server.
2064 If <server> argument is specified the command must be sent to
2065 the requested server.
2067 Reply messages to the command:
2070 Arguments: (1) <Status Payload> (2) <Server ID>
2073 This command replies with the Server ID of the server and a
2074 string which tells the information about the server.
2079 SILC_STATUS_ERR_WILDCARDS
2080 SILC_STATUS_ERR_NOT_REGISTERED
2081 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2082 SILC_STATUS_ERR_TOO_MANY_PARAMS
2083 SILC_STATUS_ERR_NO_SUCH_SERVER
2086 11 SILC_COMMAND_CONNECT
2089 Arguments: (1) <Server ID>
2090 (2) [<remote server/router>[ <port>]]
2092 This command is used by operators to force a server to try to
2093 establish a new connection to another router (if the connecting
2094 server is normal server) or server (if the conneceting server is
2095 router server). Operator may specify the server/router to be
2096 connected by setting <remote server> argument. The separator
2097 between <remote server address> and <port> is whitespace (` ').
2099 Reply messages to the command:
2102 Arguments: (1) <Status Payload>
2104 This command replies only with Status Payload.
2111 SILC_STATUS_ERR_WILDCARDS
2112 SILC_STATUS_ERR_NOT_REGISTERED
2113 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2114 SILC_STATUS_ERR_TOO_MANY_PARAMS
2115 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2116 SILC_STATUS_ERR_NO_SERVER_PRIV
2117 SILC_STATUS_ERR_NO_ROUTER_PRIV
2120 12 SILC_COMMAND_PING
2123 Arguments: (1) <Server ID>
2125 This command is used by client and server to test the communication
2126 channel to its server if one suspects that the communication is not
2127 working correctly. The <Server ID> is the ID of the server the
2128 sender is connected to.
2130 Reply messages to the command:
2133 Arguments: (1) <Status Payload>
2135 This command replies only with Status Payload. Server returns
2136 SILC_STATUS_OK in Status Payload if pinging was successful.
2141 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2142 SILC_STATUS_ERR_TOO_MANY_PARAMS
2143 SILC_STATUS_ERR_NO_SERVER_ID
2144 SILC_STATUS_ERR_NO_SUCH_SERVER
2145 SILC_STATUS_ERR_NOT_REGISTERED
2148 13 SILC_COMMAND_OPER
2151 Arguments: (1) <username> (2) <authentication data>
2153 This command is used by normal client to obtain server operator
2154 privileges on some server or router. Note that router operator
2155 has router privileges that supersedes the server operator
2156 privileges and this does not obtain those privileges. Client
2157 must use SILCOPER command to obtain router level privileges.
2159 The <username> is the username set in the server configurations
2160 as operator. The <authentication data> is the data that the
2161 client is authenticated against. It may be passphrase prompted
2162 for user on client's screen or it may be public key
2163 authentication data (data signed with private key), or
2166 Reply messages to the command:
2169 Arguments: (1) <Status Payload>
2171 This command replies only with Status Payload.
2176 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2177 SILC_STATUS_ERR_TOO_MANY_PARAMS
2178 SILC_STATUS_ERR_NOT_REGISTERED
2179 SILC_STATUS_ERR_BAD_PASSWORD
2180 SILC_STATUS_ERR_AUTH_FAILED
2183 14 SILC_COMMAND_JOIN
2186 Arguments: (1) <channel> (2) [<passphrase>]
2189 Join to channel/create new channel. This command is used to
2190 join to a channel. If the channel does not exist the channel is
2191 created. If server is normal server this command must be forwarded
2192 to router who will create the channel. The channel may be protected
2193 with passphrase. If this is the case the passphrase must be sent
2194 along the join command.
2196 The name of the <channel> must not include any spaces (` '),
2197 non-printable characters, commas (`,') or any wildcard characters.
2199 Cipher to be used to secure the traffic on the channel may be
2200 requested by sending the name of the requested <cipher>. This
2201 is used only if the channel does not exist and is created. If
2202 the channel already exists the cipher set previously for the
2203 channel will be used to secure the traffic.
2205 The server must check whether the user is allowed to join to
2206 the requested channel. Various modes set to the channel affect
2207 the ability of the user to join the channel. These conditions
2210 o The user must be invited to the channel if the channel
2211 is invite-only channel.
2213 o The Client ID/nickname/username/hostname must not match
2216 o The correct passphrase must be provided if passphrase
2217 is set to the channel.
2219 o The user count limit, if set, must not be reached.
2221 Reply messages to the command:
2224 Arguments: (1) <Status Payload> (2) <channel>
2225 (3) <Channel ID> (4) <channel mode mask>
2226 (5) [<ban mask>] (6) [<invite list>]
2229 This command replies with the channel name requested by the
2230 client, channel ID of the channel and topic of the channel
2231 if it exists. It also replies with the channel mode mask
2232 which tells all the modes set on the channel. If the
2233 channel is created the mode mask is zero (0). If ban mask
2234 and/or invite list is set they are sent as well.
2236 Client must not start transmitting to the channel even after
2237 server has replied to this command. Client is permitted to
2238 start transmitting on channel after server has sent packet
2239 SILC_PACKET_CHANNEL_KEY to the client.
2244 SILC_STATUS_ERR_WILDCARDS
2245 SILC_STATUS_ERR_NOT_REGISTERED
2246 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2247 SILC_STATUS_ERR_TOO_MANY_PARAMS
2248 SILC_STATUS_ERR_BAD_PASSWORD
2249 SILC_STATUS_ERR_CHANNEL_IS_FULL
2250 SILC_STATUS_ERR_NOT_INVITED
2251 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
2252 SILC_STATUS_ERR_BAD_CHANNEL
2253 SILC_STATUS_ERR_USER_ON_CHANNEL
2256 15 SILC_COMMAND_MOTD
2259 Arguments: (1) <server>
2261 This command is used to query the Message of the Day of a server.
2263 Reply messages to the command:
2266 Arguments: (1) <Status Payload> (2) [<motd>]
2268 This command replies with the motd message if it exists.
2273 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2274 SILC_STATUS_ERR_TOO_MANY_PARAMS
2275 SILC_STATUS_ERR_NOT_REGISTERED
2276 SILC_STATUS_ERR_NO_SUCH_SERVER
2279 16 SILC_COMMAND_UMODE
2282 Arguments: (1) <Client ID> (2) <client mode mask>
2284 This command is used by client to set/unset modes for itself.
2285 However, there are some modes that the client may not set itself,
2286 but they will be set by server. However, client may unset any
2287 mode. Modes may be masked together ORing them thus having
2288 several modes set. Client must keep its client mode mask
2289 locally so that the mode setting/unsetting would work without
2290 problems. Client may change only its own modes.
2292 Following client modes are defined:
2294 0x0000 SILC_UMODE_NONE
2296 No specific mode for client. This is the initial
2297 setting when new client is created. The client is
2301 0x0001 SILC_UMODE_SERVER_OPERATOR
2303 Marks the user as server operator. Client cannot
2304 set this mode itself. Server sets this mode to the
2305 client when client attains the server operator
2306 privileges by SILC_COMMAND_OPER command. Client
2307 may unset the mode itself.
2310 0x0002 SILC_UMODE_ROUTER_OPERATOR
2312 Marks the user as router (SILC) operator. Client
2313 cannot this mode itself. Router sets this mode to
2314 the client when client attains the router operator
2315 privileges by SILC_COMMAND_SILCOPER command. Client
2316 may unset the mode itself.
2318 Reply messages to the command:
2321 Arguments: (1) <Status Payload> (2) <client mode mask>
2323 This command replies with the changed client mode mask that
2324 the client is required to keep locally.
2330 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2331 SILC_STATUS_ERR_TOO_MANY_PARAMS
2332 SILC_STATUS_ERR_NOT_REGISTERED
2333 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2334 SILC_STATUS_ERR_BAD_CLIENT_ID
2335 SILC_STATUS_ERR_NOT_YOU
2336 SILC_STATUS_ERR_UNKNOWN_MODE
2337 SILC_STATUS_ERR_NO_RECIPIENT
2338 SILC_STATUS_ERR_NO_CLIENT_ID
2341 17 SILC_COMMAND_CMODE
2344 Arguments: (1) <Channel ID> (2) <channel mode mask>
2345 (3) [<user limit>] (4) [<passphrase>]
2346 (5) [<ban mask>] (6) [<invite list>]
2347 (7) [<Client ID>] (8) [<cipher>[:<key len>]]
2349 This command is used by client to set or change channel flags on
2350 a channel. Channel has several modes that set various properties
2351 of a channel. Modes may be masked together by ORing them thus
2352 having several modes set. The <Channel ID> is the ID of the
2353 target channel. The client changing channel mode must be on
2354 the same channel and poses sufficient privileges to be able to
2357 Following channel modes are defined:
2359 0x0000 SILC_CMODE_NONE
2361 No specific mode on channel. This is the default when
2362 channel is created. This means that channel is just plain
2366 0x0001 SILC_CMODE_PRIVATE
2368 Channel is private channel. Private channels are shown
2369 in the channel list listed with SILC_COMMAND_LIST command
2370 with indicatioin that the channel is private. Also,
2371 client on private channel will no be detected to be on
2372 the channel as the channel is not shown in the client's
2373 currently joined channel list. Channel founder and
2374 channel operator may set/unset this mode.
2376 Typical implementation would use [+|-]p on user interface
2377 to set/unset this mode.
2380 0x0002 SILC_CMODE_SECRET
2382 Channel is secret channel. Secret channels are not shown
2383 in the list listed with SILC_COMMAND_LIST command. Secret
2384 channels can be considered to be invisible channels.
2385 Channel founder and channel operator may set/unset this
2388 Typical implementation would use [+|-]s on user interface
2389 to set/unset this mode.
2392 0x0004 SILC_CMODE_PRIVKEY
2394 Channel uses private channel key to protect the traffic
2395 on the channel. When this mode is set the client will be
2396 responsible to set the key it wants to use to encrypt and
2397 decrypt the traffic on channel. Server generated channel
2398 keys are not used at all. This mode provides additional
2399 security as clients on channel may agree to use private
2400 channel key that even servers do not know. Naturally,
2401 this requires that every client on the channel knows
2402 the key before hand (it is considered to be pre-shared-
2403 key). This specification does not define how the private
2404 channel key is set as it is entirely local setting on
2407 As it is local setting it is possible to have several
2408 private channel keys on one channel. In this case several
2409 clients can talk on same channel but only those clients
2410 that share the key with the message sender will be able
2411 to hear the talking. Client should not display those
2412 message for the end user that it is not able to decrypt
2413 when this mode is set.
2415 Only channel founder may set/unset this mode. If this
2416 mode is unset the server will distribute new channel
2417 key to all clients on the channel which will be used
2420 Typical implementation would use [+|-]k on user interface
2421 to set/unset this mode.
2424 0x0008 SILC_CMODE_INVITE
2426 Channel is invite only channel. Client may join to this
2427 channel only if it is invited to the channel. Channel
2428 founder and channel operator may set/unset this mode.
2430 Typical implementation would use [+|-]i on user interface
2431 to set/unset this mode.
2434 0x0010 SILC_CMODE_TOPIC
2436 The topic of the channel may only be set by client that
2437 is channel founder or channel operator. Normal clients
2438 on channel will not be able to set topic when this mode
2439 is set. Channel founder and channel operator may set/
2442 Typical implementation would use [+|-]t on user interface
2443 to set/unset this mode.
2446 0x0020 SILC_CMODE_ULIMIT
2448 User limit has been set to the channel. New clients
2449 may not join to the channel when the limit set is
2450 reached. Channel founder and channel operator may set/
2451 unset the limit. The <user limit> argument is the
2452 number of limited users.
2454 Typical implementation would use [+|-]l on user interface
2455 to set/unset this mode.
2458 0x0040 SILC_CMODE_PASSPHRASE
2460 Passphrase has been set to the channel. Client may
2461 join to the channel only if it is able to provide the
2462 correct passphrase. Setting passphrases to channel
2463 is entirely safe as all commands are protected in the
2464 SILC network. Only channel founder may set/unset
2465 the passphrase. The <passphrase> argument is the
2468 Typical implementation would use [+|-]a on user interface
2469 to set/unset this mode.
2472 0x0080 SILC_CMODE_BAN
2474 Ban mask has been set to the channel. The ban mask
2475 may be used to ban specific clients to join the channel.
2476 The <ban mask> argument is the set ban mask. When
2477 unsetting a ban mask the mask must be provided as
2478 argument. Channel founder and channel operator may
2479 set/unset this mode. Channel founder may not be
2480 added to the ban list.
2482 Typical implementation would use [+|-]b on user interface
2483 to set/unset this mode.
2486 0x0100 SILC_CMODE_INVITE
2488 Invite list has been set to the channel. The invite list
2489 can be used to mark the clients that is able to join
2490 channel without being invited when the channel is set to
2491 be invite-only channel. The <invite list> argument is the
2492 set invite mask. When unsetting entry from the invite list
2493 the entry must be provided as argument. Channel founder and
2494 channel operator may set/unset this mode.
2496 Typical implementation would use [+|-]I on user interface
2497 to set/unset this mode.
2500 0x0200 SILC_CMODE_OPERATOR
2502 Sets channel operator privileges on the channel for a
2503 client on the channel. The <Client ID> argument is the
2504 target client on the channel. Channel founder and
2505 channel operator may set/unset (promote/demote) this
2508 Typical implementation would use [+|-]o on user interface
2509 to set/unset this mode.
2512 0x0400 SILC_CMODE_CIPHER
2514 Sets specific cipher to be used to protect channel
2515 traffic. The <cipher> argument is the requested cipher.
2516 When set or unset the server must re-generate new
2517 channel key. If <key len> argument is specified with
2518 <cipher> argument the new key is generated of <key len>
2521 Typical implementation would use [+|-]c on user interface
2522 to set/unset this mode.
2525 To make the mode system work, client must keep the channel mode
2526 mask locally so that the mode setting and unsetting would work
2527 without problems. The client receives the initial channel mode
2528 mask when it joins to the channel. When the mode changes on
2529 channel the server distributes the changed channel mode mask to
2530 all clients on the channel by sending SILC_COMMAND_CMODE command
2534 Reply messages to the command:
2537 Arguments: (1) <Status Payload> (2) <channel mode mask>
2539 This command replies with the changed channel mode mask that
2540 client is required to keep locally. The same mask is also
2541 sent to all clients on channel by sending additional command
2547 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2548 SILC_STATUS_ERR_TOO_MANY_PARAMS
2549 SILC_STATUS_ERR_NOT_REGISTERED
2550 SILC_STATUS_ERR_NOT_ON_CHANNEL
2551 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2552 SILC_STATUS_ERR_BAD_CHANNEL_ID
2553 SILC_STATUS_ERR_NO_CHANNEL_ID
2554 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2555 SILC_STATUS_ERR_UNKNOWN_MODE
2556 SILC_STATUS_ERR_NO_CLIENT_ID
2561 18 SILC_COMMAND_KICK
2564 Arguments: (1) <channel> (2) <Client ID>
2567 This command is used by channel operators to remove a client from
2568 channel. The <channel> argument is the channel the client to be
2569 removed is on currently. Note that the "kicker" must be on the same
2570 channel. If <comment> is provided it will be sent to the removed
2573 Reply messages to the command:
2576 Arguments: (1) <Status Payload>
2578 This command replies only with Status Payload.
2583 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2584 SILC_STATUS_ERR_TOO_MANY_PARAMS
2585 SILC_STATUS_ERR_NOT_REGISTERED
2586 SILC_STATUS_ERR_NO_SUCH_CHANNEL
2587 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2588 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2589 SILC_STATUS_ERR_NO_CLIENT_ID
2592 19 SILC_COMMAND_RESTART
2597 This command may only be used by server operator to force a
2598 server to restart itself.
2600 Reply messages to the command:
2603 Arguments: (1) <Status Payload>
2605 This command replies only with Status Payload.
2612 SILC_STATUS_ERR_NOT_REGISTERED
2613 SILC_STATUS_ERR_NO_SERVER_PRIV
2616 20 SILC_COMMAND_CLOSE
2619 Arguments: (1) <Server ID>
2621 This command is used only by operator to close connection to a
2622 remote site. The <Server ID> argument is the ID of the remote
2623 site and must be valid.
2625 Reply messages to the command:
2628 Arguments: (1) <Status Payload>
2630 This command replies only with Status Payload.
2637 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2638 SILC_STATUS_ERR_TOO_MANY_PARAMS
2639 SILC_STATUS_ERR_NOT_REGISTERED
2640 SILC_STATUS_ERR_NO_SUCH_SERVER
2641 SILC_STATUS_ERR_NO_SERVER_PRIV
2642 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2650 This command is used only by operator to shutdown the server.
2651 All connections to the server will be closed and the server is
2654 Reply messages to the command:
2659 Arguments: (1) <Status Payload>
2661 This command replies only with Status Payload.
2666 SILC_STATUS_ERR_NOT_REGISTERED
2667 SILC_STATUS_ERR_NO_SERVER_PRIV
2670 22 SILC_COMMAND_SILCOPER
2673 Arguments: (1) <username> (2) <authentication data>
2675 This command is used by normal client to obtain router operator
2676 privileges (also known as SILC operator) on some router. Note
2677 that router operator has router privileges that supersedes the
2678 server operator privileges.
2680 The <username> is the username set in the server configurations
2681 as operator. The <authentication data> is the data that the
2682 client is authenticated against. It may be passphrase prompted
2683 for user on client's screen or it may be public key
2684 authentication data (data signed with private key), or
2687 Difference between router operator and server operator is that
2688 router operator is able to handle cell level properties while
2689 server operator (even on router server) is able to handle only
2690 local properties, such as, local connections and normal server
2693 Reply messages to the command:
2696 Arguments: (1) <Status Payload>
2698 This command replies only with Status Payload.
2703 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2704 SILC_STATUS_ERR_TOO_MANY_PARAMS
2705 SILC_STATUS_ERR_NOT_REGISTERED
2706 SILC_STATUS_ERR_BAD_PASSWORD
2707 SILC_STATUS_ERR_AUTH_FAILED
2710 23 SILC_COMMAND_LEAVE
2713 Arguments: (1) <Channel ID>
2715 This command is used by client to leave a channel the client is
2716 joined to. After a client has leaved the channel the server
2717 must create new key for the channel and distribute to all clients
2718 still currently on the channel.
2720 Reply messages to the command:
2723 Arguments: (1) <Status Payload>
2725 This command replies only with Status Payload.
2730 SILC_STATUS_ERR_NOT_REGISTERED
2731 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2732 SILC_STATUS_ERR_TOO_MANY_PARAMS
2733 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2734 SILC_STATUS_ERR_BAD_CHANNEL_ID
2735 SILC_STATUS_ERR_NO_CHANNEL_ID
2738 24 SILC_COMMAND_NAMES
2741 Arguments: (1) <Channel ID>
2743 This command is used to list user names currently on the requested
2744 channel; argument <Channel ID>. The server must resolve the
2745 user names and send a comma (`,') separated list of user names
2746 on the channel. Server or router may resolve the names by sending
2747 SILC_COMMAND_WHOIS commands.
2749 If the requested channel is a private or secret channel, this
2750 command must not send the list of users, as private and secret
2751 channels cannot be seen by outside. In this case the returned
2752 name list may include a indication that the server could not
2753 resolve the names of the users on the channel.
2755 Reply messages to the command:
2758 Arguments: (1) <Status Payload> (2) <Channel ID>
2759 (3) <name list> (4) <Client ID list>
2761 This command replies with the Channel ID of the requested channel,
2762 comma separated list of users on the channel and Client ID list
2763 of the users on the list. The Client ID list has Client ID's
2764 of all users in the list. First Client ID in the list must be
2765 the Client ID of the first user in <name list>. The Client ID
2766 List is formed by adding Client ID's each after each. Note that
2767 the Client ID list is binary data.
2772 SILC_STATUS_ERR_NOT_REGISTERED
2773 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2774 SILC_STATUS_ERR_TOO_MANY_PARAMS
2775 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2776 SILC_STATUS_ERR_BAD_CHANNEL_ID
2777 SILC_STATUS_ERR_NO_CHANNEL_ID
2778 SILC_STATUS_ERR_NOT_ON_CHANNEL
2783 Currently undefined commands.
2786 255 SILC_COMMAND_MAX
2788 Reserved command. This must not be sent.
2793 5.3 SILC Command Status Types
2796 5.3.1 SILC Command Status Payload
2798 Command Status Payload is sent in command reply messages to indicate
2799 the status of the command. The payload is one of argument in the
2800 command thus this is the data area in Command Argument Payload described
2801 in [SILC2]. The payload is only 2 bytes of length. Following diagram
2802 represents the Command Status Payload (field is always in MSB order).
2808 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
2809 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2811 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2815 Figure 5: SILC Command Status Payload
2819 o Status Message (2 bytes) - Indicates the status message.
2820 All Status messages are described in the next section.
2825 5.3.2 SILC Command Status List
2827 Command Status messages are returned in the command reply messages
2828 to indicate whether the command were executed without errors. If error
2829 has occured the status tells which error occured. Status payload only
2830 sends numeric reply about the status. Receiver of the payload must
2831 convert the numeric values into human readable error messages. The
2832 list of status messages below has an example human readable error
2833 messages that client may display for the user.
2835 List of all defined command status messages following.
2838 Generic status messages:
2842 Ok status. Everything went Ok. The status payload maybe
2843 safely ignored in this case.
2845 1 SILC_STATUS_LIST_START
2847 Start of the list. There will be several command replies and
2848 this reply is the start of the list.
2850 2 SILC_STATUS_LIST_END
2852 End of the list. There were several command replies and this
2853 reply is the last of the list. There won't be other replies
2854 beloning to this list after this one.
2858 Currently undefined and has been reserved for the future.
2861 Error status message:
2863 10 SILC_STATUS_ERR_NO_SUCH_NICK
2865 "No such nickname". Requested nickname does not exist.
2867 11 SILC_STATUS_ERR_NO_SUCH_CHANNEL
2869 "No such channel". Requested channel name does not exist.
2871 12 SILC_STATUS_ERR_NO_SUCH_SERVER
2873 "No such server". Requested server name does not exist.
2875 13 SILC_STATUS_ERR_TOO_MANY_TARGETS
2877 "Duplicate recipients. No message delivered". Message were
2878 tried to be sent to recipient which has several occurrences in
2881 14 SILC_STATUS_ERR_NO_RECIPIENT
2883 "No recipient given". Command required recipient which was
2886 15 SILC_STATUS_ERR_UNKNOWN_COMMAND
2888 "Unknown command". Command sent to server is unknown by the
2891 16 SILC_STATUS_ERR_WILDCARDS
2893 "Wildcards cannot be used". Wildcards were provided but they
2896 17 SILC_STATUS_ERR_NO_CLIENT_ID
2898 "No Client ID given". Client ID were expected as command
2899 parameter but were not found.
2901 18 SILC_STATUS_ERR_NO_CHANNEL_ID
2903 "No Channel ID given". Channel ID were expected as command
2904 parameter but were not found.
2906 19 SILC_STATUS_ERR_NO_SERVER_ID
2908 "No Serve ID given". Server ID were expected as command
2909 parameter but were not found.
2911 20 SILC_STATUS_ERR_BAD_CLIENT_ID
2913 "Bad Client ID". Client ID provided were erroneous.
2915 21 SILC_STATUS_ERR_BAD_CHANNEL_ID
2917 "Bad Channel ID". Channel ID provided were erroneous.
2919 22 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2921 "No such Client ID". Client ID provided does not exist.
2924 23 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2926 "No such Channel ID". Channel ID provided does not exist.
2928 24 SILC_STATUS_ERR_NICKNAME_IN_USE
2930 "Nickname already exists". Nickname created could not be
2931 registered because number of same nicknames were already set to
2932 maximum. This is not expected to happen in real life but is
2935 25 SILC_STATUS_ERR_NOT_ON_CHANNEL
2937 "You are not on that channel". The command were specified for
2938 client user is not currently on.
2940 26 SILC_STATUS_ERR_USER_ON_CHANNEL
2942 "User already on channel". User were invited on channel they
2945 27 SILC_STATUS_ERR_NOT_REGISTERED
2947 "You have not registered". User executed command that requires
2948 the client to be registered on the server before it may be
2951 28 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2953 "Not enough parameters". Command requires more parameters
2956 29 SILC_STATUS_ERR_TOO_MANY_PARAMS
2958 "Too many parameters". Too many parameters were provided
2961 30 SILC_STATUS_ERR_PERM_DENIED
2963 "Your host is not among the privileged". The client tried to
2964 register on server that does not allow this host to connect.
2966 31 SILC_STATUS_ERR_BANNED_FROM_SERVER
2968 "You are banned from this server". The client tried to register
2969 on server that has explicitly denied this host to connect.
2973 32 SILC_STATUS_ERR_BAD_PASSWORD
2975 "Cannot join channel. Incorrect password". Password provided for
2976 channel were not accepted.
2978 33 SILC_STATUS_ERR_CHANNEL_IS_FULL
2980 "Cannot join channel. Channel is full". The channel is full
2981 and client cannot be joined to it.
2983 34 SILC_STATUS_ERR_NOT_INVITED
2985 "Cannot join channel. You have not been invited". The channel
2986 is invite only channel and client has not been invited.
2988 35 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
2990 "Cannot join channel. You have been banned". The client has
2991 been banned from the channel.
2993 36 SILC_STATUS_ERR_UNKNOWN_MODE
2995 "Unknown mode". Mode provided by the client were unknown to
2998 37 SILC_STATUS_ERR_NOT_YOU
3000 "Cannot change mode for other users". User tried to change
3001 someone else's mode.
3003 38 SILC_STATUS_ERR_NO_CHANNEL_PRIV
3005 "Permission denied. You are not channel operator". Command may
3006 be executed only by channel operator.
3008 39 SILC_STATUS_ERR_NO_SERVER_PRIV
3010 "Permission denied. You are not server operator". Command may
3011 be executed only by server operator.
3013 40 SILC_STATUS_ERR_NO_ROUTER_PRIV
3015 "Permission denied. You are not SILC operator". Command may be
3016 executed only by router (SILC) operator.
3018 41 SILC_STATUS_ERR_BAD_NICKNAME
3020 "Bad nickname". Nickname requested contained illegal characters
3023 42 SILC_STATUS_ERR_BAD_CHANNEL
3025 "Bad channel name". Channel requested contained illegal characters
3028 43 SILC_STATUS_ERR_AUTH_FAILED
3030 "Authentication failed". The authentication data sent as
3031 argument were wrong and thus authentication failed.
3036 6 Security Considerations
3038 Security is central to the design of this protocol, and these security
3039 considerations permeate the specification.
3048 [SILC2] Riikonen, P., "SILC Packet Protocol", Internet Draft,
3051 [SILC3] Riikonen, P., "SILC Key Exchange and Authentication
3052 Protocols", Internet Draft, June 2000.
3054 [IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
3057 [SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
3060 [PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
3063 [SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
3066 [PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
3067 Infrastructure, Certificate and CRL Profile", RFC 2459,
3070 [Schneier] Schneier, B., "Applied Cryptography Second Edition",
3071 John Wiley & Sons, New York, NY, 1996.
3073 [Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
3076 [OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
3077 RFC 2412, November 1998.
3079 [ISAKMP] Maughan D., et al, "Internet Security Association and
3080 Key Management Protocol (ISAKMP)", RFC 2408, November
3083 [IKE] Harkins D., and Carrel D., "The Internet Key Exhange
3084 (IKE)", RFC 2409, November 1998.
3086 [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
3087 Authentication", RFC 2104, February 1997.
3100 EMail: priikone@poseidon.pspt.fi
3102 This Internet-Draft expires 13 May 2001