8 .ds RF FORMFEED[Page %]
17 Network Working Group P. Riikonen
19 draft-riikonen-silc-spec-02.txt XXXXXXXXXXXXXXX
25 Secure Internet Live Conferencing (SILC),
26 Protocol Specification
27 <draft-riikonen-silc-spec-02.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 2.5 Router Connections ........................................ 7
82 2.6 Backup Routers ............................................ XX
83 3 SILC Specification ............................................ 8
84 3.1 Client .................................................... 8
85 3.1.1 Client ID ........................................... 9
86 3.2 Server .................................................... 10
87 3.2.1 Server's Local ID List .............................. 10
88 3.2.2 Server ID ........................................... 11
89 3.2.3 SILC Server Ports ................................... 11
90 3.3 Router .................................................... 12
91 3.3.1 Router's Local ID List .............................. 12
92 3.3.2 Router's Global ID List ............................. 13
93 3.3.3 Router's Server ID .................................. 13
94 3.4 Channels .................................................. 14
95 3.4.1 Channel ID .......................................... 15
96 3.5 Operators ................................................. 15
97 3.6 SILC Commands ............................................. 15
98 3.7 SILC Packets .............................................. 16
99 3.8 Packet Encryption ......................................... 16
100 3.8.1 Determination of the Source and the Destination ..... 17
101 3.8.2 Client To Client .................................... 17
102 3.8.3 Client To Channel ................................... 19
103 3.8.4 Server To Server .................................... 19
104 3.9 Key Exchange And Authentication ........................... 20
105 3.10 Algorithms ............................................... 20
106 3.10.1 Ciphers ............................................ 20
107 3.10.2 Public Key Algorithms .............................. 21
108 3.10.3 Hash Functions ..................................... XXX
109 3.10.4 MAC Algorithms ..................................... XXX
110 3.10.5 Compression Algorithms ............................. XXX
111 3.11 SILC Public Key .......................................... 22
112 3.12 SILC Version Detection ................................... 24
113 4 SILC Procedures ............................................... 25
114 4.1 Creating Client Connection ................................ 25
115 4.2 Creating Server Connection ................................ 26
116 4.3 Joining to a Channel ...................................... 27
117 4.4 Channel Key Generation .................................... 28
118 4.5 Private Message Sending and Reception ..................... 29
119 4.6 Private Message Key Generation ............................ 29
120 4.7 Channel Message Sending and Reception ..................... 30
121 4.8 Session Key Regeneration .................................. 30
122 4.9 Command Sending and Reception ............................. 30
123 5 SILC Commands ................................................. 31
124 5.1 SILC Commands Syntax ...................................... 31
125 5.2 SILC Commands List ........................................ 33
126 5.3 SILC Command Status Types ................................. 56
127 5.3.1 SILC Command Status Payload ......................... 56
128 5.3.2 SILC Command Status List ............................ 57
129 6 Security Considerations ....................................... 61
130 7 References .................................................... 61
131 8 Author's Address .............................................. 62
138 Figure 1: SILC Network Topology
139 Figure 2: Communication Inside cell
140 Figure 3: Communication Between Cells
141 Figure 4: Router Connections
142 Figure 5: SILC Public Key
143 Figure 6: SILC Command Status Payload
149 This document describes a Secure Internet Live Conferencing (SILC)
150 protocol which provides secure conferencing services over insecure
151 network channel. SILC is IRC [IRC] like protocol, however, it is
152 not equivalent to IRC and does not support IRC.
154 Strong cryptographic methods are used to protect SILC packets inside
155 SILC network. Two other Internet Drafts relates very closely to this
156 memo; SILC Packet Protocol [SILC2] and SILC Key Exchange and
157 Authentication Protocols [SILC3].
159 The protocol uses extensively packets as conferencing protocol
160 requires message and command sending. The SILC Packet Protocol is
161 described in [SILC2] and should be read to fully comprehend this
162 document and protocol. [SILC2] also describes the packet encryption
163 and decryption in detail.
165 The security of SILC protocol and for any security protocol for that
166 matter is based on strong and secure key exchange protocol. The SILC
167 Key Exchange protocol is described in [SILC3] along with connection
168 authentication protocol and should be read to fully comprehend this
169 document and protocol.
171 The SILC protocol has been developed to work on TCP/IP network
172 protocol, although it could be made to work on other network protocols
173 with only minor changes. However, it is recommended that TCP/IP
174 protocol is used under SILC protocol. Typical implementation would
175 be made in client-server model.
181 This section describes various SILC protocol concepts that forms the
182 actual protocol, and in the end, the actual SILC network. The mission
183 of the protocol is to deliver messages from clients to other clients
184 through routers and servers in secure manner. The messages may also
185 be delivered from one client to many clients forming a group, also
188 This section does not focus to security issues, instead basic network
189 concepts are introduced to make the topology of the SILC network
194 2.1 SILC Network Topology
196 SILC network is a cellular network as opposed to tree style network
197 topology. The rationale for this is to have servers that can perform
198 specific kind of tasks what other servers cannot perform. This leads
199 to two kinds of servers; normal SILC servers and SILC routers.
201 A difference between normal server and router server is that routers
202 knows everything about everything in the network. They also do the
203 actual routing of the messages to the correct receiver. Normal servers
204 knows only about local information and nothing about global information.
205 This makes the network faster as there are less servers that needs to
206 keep global information up to date at all time.
208 This, on the other hand, leads to cellular like network, where routers
209 are in the center of the cell and servers are connected to the router.
211 The following diagram represents SILC network topology.
231 ---- ---- ---- ---- ---- ----
232 | S8 | S5 | S4 | | S7 | S5 | S6 |
233 ----- ---- ----- ----- ---- -----
234 | S7 | S/R1 | S2 | --- | S8 | S/R2 | S4 |
235 ---- ------ ---- ---- ------ ----
236 | S6 | S3 | S1 | | S1 | S3 | S2 | ---- ----
237 ---- ---- ---- ---- ---- ---- | S3 | S1 |
238 Cell 1. \\ Cell 2. | \\____ ----- -----
240 ---- ---- ---- ---- ---- ---- ---- ------
241 | S7 | S4 | S2 | | S1 | S3 | S2 | | S2 | S5 |
242 ----- ---- ----- ----- ---- ----- ---- ----
243 | S6 | S/R3 | S1 | --- | S4 | S/R5 | S5 | ____/ Cell 4.
244 ---- ------ ---- ---- ------ ----
245 | S8 | S5 | S3 | | S6 | S7 | S8 | ... etc ...
246 ---- ---- ---- ---- ---- ----
251 Figure 1: SILC Network Topology
254 A cell is formed when a server or servers connect to one router. In
255 SILC network normal server cannot directly connect to other normal
256 server. Normal server may only connect to SILC router which then
257 routes the messages to the other servers in the cell. Router servers
258 on the other hand may connect to other routers to form the actual SILC
259 network, as seen in above figure. However, router is also normal SILC
260 server; clients may connect to it the same way as to normal SILC
261 servers. Normal server also cannot have active connections to more
262 than one router. Normal server cannot be connected to two different
263 cells. Router servers, on the other hand, may have as many router to
264 router connections as needed.
266 There are many issues in this network topology that needs to be careful
267 about. Issues like the size of the cells, the number of the routers in
268 the SILC network and the capacity requirements of the routers. These
269 issues should be discussed in the Internet Community and additional
270 documents on the issue will be written.
274 2.2 Communication Inside a Cell
276 It is always guaranteed that inside a cell message is delivered to the
277 recipient with at most two server hops. Client who is connected to
278 server in the cell and is talking on channel to other client connected
279 to other server in the same cell, will have its messages delivered from
280 its local server first to the router of the cell, and from the router
281 to the other server in the cell.
283 The following diagram represents this scenario:
297 Figure 2: Communication Inside cell
300 Example: Client 1. connected to Server 1. message sent to
301 Client 4. connected to Server 2. travels from Server 1.
302 first to Router which routes the message to Server 2.
303 which then sends it to the Client 4. All the other
304 servers in the cell will not see the routed message.
307 If client is connected directly to the router, as router is also normal
308 SILC server, the messages inside the cell are always delivered only with
309 one server hop. If clients communicating with each other are connected
310 to the same server, no router interaction is needed. This is the optimal
311 situation of message delivery in the SILC network.
315 2.3 Communication in the Network
317 If the message is destined to server that does not belong to local cell
318 the message is routed to the router server to which the destination
319 server belongs, if the local router is connected to destination router.
320 If there is no direct connection to the destination router, the local
321 router routes the message to its primary route. The following diagram
322 represents message sending between cells.
327 1 --- S1 S4 --- 5 S2 --- 1
328 S/R - - - - - - - - S/R
338 Figure 3: Communication Between Cells
341 Example: Client 5. connected to Server 4. in Cell 1. message sent
342 to Client 2. connected to Server 1. in Cell 2. travels
343 from Server 4. to Router which routes the message to
344 Router in Cell 2, which then routes the message to
345 Server 1. All the other servers and routers in the
346 network will not see the routed message.
349 The optimal case of message delivery from client point of view is
350 when clients are connected directly to the routers and the messages
351 are delivered from one router to the other router.
355 2.4 Channel Communication
357 Messages may be sent to group of clients as well. Sending messages to
358 many clients works the same way as sending messages point to point, from
359 message delivery point of view. Security issues are another matter
360 which are not discussed in this section.
362 Router server handles the message routing to multiple recipients. If
363 any recipient is not in the same cell as the sender the messages are
366 Server distributes the channel message to its local clients who are
367 joined to the channel. Also, router distributes the message to its
368 local clients on the channel.
372 2.5 Router Connections
374 Router connections play very important role in making the SILC like
375 network topology to work. For example, sending broadcast packets in
376 SILC network require special connections between routers; routers must
377 be connected in specific way.
379 Every router has their primary route which is a connection to another
380 router in the network. Unless there is only two routers in the network
381 must not routers use each other as their primary routes. The router
382 connections in the network must form a circular.
384 Example with three routers in the network:
394 S/R1 - > - > - > - > - > - > - S/R2
397 \\ - < - < - S/R3 - < - < - /
402 Figure 4: Router Connections
405 Example: Network with three routers. Router 1. uses Router 2. as its
406 primary router. Router 2. uses Router 3. as its primary router,
407 and Router 3. uses Router 1. as its primary router. There may
408 be other direct connections between the routers but they must
409 not be used as primary routes.
411 The above example is applicable to any amount of routers in the network
412 except for two routers. If there are only two routers in the network both
413 routers must be able to handle situation where they use each other as their
416 The issue of router connections are very important especially with SILC
417 broadcast packets. Usually all router wide information in the network is
418 distributed by SILC broadcast packets.
424 Backup routers may exist in the cell in addition of the primary router.
425 However, they must not be active routers and act as routers in the cell.
426 Only one router may be acting as primary router in the cell. In the case
427 of failure of the primary router may one of the backup routers become
428 active. The purpose of backup routers are in case of failure of the
429 primary router to maintain working connections inside the cell and outside
430 the cell and to avoid netsplits.
432 Backup routers are normal servers in the cell that are prepared to take
433 over the tasks of primary router if needed. They need to have at least
434 one direct and active connection to the primary router of the cell.
435 This communication channel is used to send the router information to
436 the backup router. Backup router must know everything that the primary
437 router knows to be able to take over the tasks of the primary router.
438 It is the primary router's responsibility to feed the data to the backup
439 router. If the backup router does not know all the data in the case of
440 failure some connections may be lost. The primary router of the cell
441 must consider the backup router being normal router server and feed the
444 In addition of having direct connection to the primary router of the
445 cell the backup router must also have connection to the same router
446 the primary router of the cell has connected. However, it must not be
447 active router connection meaning that the backup router must not use
448 that channel as its primary route and it must not notify the router
449 about having connected servers, channels and clients behind it. It
450 merely connects to the router. This sort of connection is later
451 referred as being passive connection. Some keepalive actions may be
452 needed by the router to keep the connection alive.
454 The primary router notifies its primary router about having backup
455 routers in the cell by sending SILC_PACKET_CELL_ROUTERS packet. If
456 and when the primary router of the cell becomes unresponsive, its
457 primary router knows that there exists backup routers in the cell.
458 After that it will start using the first backup router sent in the
459 packet as router of that cell. In this case the backup router must
460 notify its new primary router about the servers, channels and clients
461 it has connected to it. The primary router knows that this server
462 has become a router of the cell because of failure of the primary
463 router in the cell. It must also cope with the fact that the servers,
464 channels and clients that the new backup router announces are not
465 really new, since they used to exist in the primary router of the
468 It is required that other normal servers has passive connections to
469 the backup router(s) in the cell. Some keepalive actions may be needed
470 by the server to keep the connection alive. After they notice the
471 failure of the primary router they must start using the connection to
472 the first backup router as their primary route.
474 It is recommended that there would be at least one backup router in
475 the cell. It is not recommended to have all servers in the cell acting
476 as backup routers as it requires establishing several connections to
477 several servers in the cell. Large cells can easily have several
478 backup routers in the cell. The order of the backup routers are decided
479 at the primary router of the cell and servers and backup servers in the
480 cell must be configured accordingly. It is not required that the backup
481 server is actually active server in the cell. Backup router may be spare
482 server in the cell that does not accept normal client connections at all.
483 It maybe reserved purely for the backup purposes. These, however, are
484 cell management issues.
486 If the first backup router is down as well and there is another backup
487 router in the cell then it will start acting as the primary router as
492 3. SILC Specification
494 This section describes the SILC protocol. However, [SILC2] and
495 [SILC3] describes other important protocols that are part of this SILC
496 specification and must be read.
502 A client is a piece of software connecting to SILC server. SILC client
503 cannot be SILC server. Purpose of clients is to provide the user
504 interface of the SILC services for end user. Clients are distinguished
505 from other clients by unique Client ID. Client ID is a 128 bit ID that
506 is used in the communication in the SILC network. The client ID is
507 based on the nickname selected by the user. User uses logical nicknames
508 in communication which are then mapped to the corresponding Client ID.
509 Client ID's are low level identifications and must not be seen by the
512 Clients provide other information about the end user as well. Information
513 such as the nickname of the user, username and the hostname of the end
514 user and user's real name. See section 3.2 Server for information of
515 the requirements of keeping this information.
517 The nickname selected by the user is not unique in the SILC network.
518 There can be 2^8 same nicknames for one IP address. As for comparison
519 to IRC [IRC] where nicknames are unique this is a fundamental difference
520 between SILC and IRC. This causes the server names to be used along
521 with the nicknames to identify specific users when sending messages.
522 This feature of SILC makes IRC style nickname-wars obsolete as no one
523 owns their nickname; there can always be someone else with the same
524 nickname. The maximum length of nickname is 128 characters.
530 Client ID is used to identify users in the SILC network. The Client ID
531 is unique to the extent that there can be 2^128 different Client ID's,
532 and ID's based on IPv6 addresses extends this to 2^224 different Client
533 ID's. Collisions are not expected to happen. The Client ID is defined
537 128 bit Client ID based on IPv4 addresses:
539 32 bit Server ID IP address (bits 1-32)
540 8 bit Random number or counter
541 88 bit Truncated MD5 hash value of the nickname
543 224 bit Client ID based on IPv6 addresses:
545 128 bit Server ID IP address (bits 1-128)
546 8 bit Random number or counter
547 88 bit Truncated MD5 hash value of the nickname
549 o Server ID IP address - Indicates the server where this
550 client is coming from. The IP address hence equals the
551 server IP address where to the client has connected.
553 o Random number or counter - Random number to further
554 randomize the Client ID. Another choice is to use
555 a counter starting from the zero (0). This makes it
556 possible to have 2^8 same nicknames from the same
559 o MD5 hash - MD5 hash value of the nickname is truncated
560 taking 88 bits from the start of the hash value. This
561 hash value is used to search the user's Client ID from
565 Collisions could occur when more than 2^8 clients using same nickname
566 from the same server IP address is connected to the SILC network.
567 Server must be able to handle this situation by refusing to accept
568 anymore of that nickname.
570 Another possible collision may happen with the truncated hash value of
571 the nickname. It could be possible to have same truncated hash value for
572 two different nicknames. However, this is not expected to happen nor
573 cause any problems if it would occur. Nicknames are usually logical and
574 it is unlikely to have two distinct logical nicknames produce same
575 truncated hash value.
581 Servers are the most important parts of the SILC network. They form the
582 basis of the SILC, providing a point to which clients may connect to.
583 There are two kinds of servers in SILC; normal servers and router servers.
584 This section focus on the normal server and router server is described
585 in the section 3.3 Router.
587 Normal servers may not directly connect to other normal server. Normal
588 servers may only directly connect to router server. If the message sent
589 by the client is destined outside the local server it is always sent to
590 the router server for further routing. Server may only have one active
591 connection to router on same port. Normal server may not connect to other
592 cell's router except in situations where its cell's router is unavailable.
594 Servers and routers in the SILC network are considered to be trusted.
595 With out a doubt, servers that are set to work on ports above 1023 are
596 not considered to be trusted. Also, the service provider acts important
597 role in the server's trustworthy.
601 3.2.1 Server's Local ID List
603 Normal server keeps various information about the clients and their end
604 users connected to it. Every normal server must keep list of all locally
605 connected clients, Client ID's, nicknames, usernames and hostnames and
606 user's real name. Normal servers only keeps local information and it
607 does not keep any global information. Hence, normal servers knows only
608 about their locally connected clients. This makes servers efficient as
609 they don't have to worry about global clients. Server is also responsible
610 of creating the Client ID's for their clients.
612 Normal server also keeps information about locally created channels and
616 Hence, local list for normal server includes:
619 server list - Router connection
630 client list - All clients in server
638 channel list - All channels in server
641 o Client ID's on channel
642 o Client ID modes on channel
651 Servers are distinguished from other servers by unique 64 bit Server ID
652 (for IPv4) or 160 bit Server ID (for IPv6). The Server ID is used in
653 the SILC to route messages to correct servers. Server ID's also provide
654 information for Client ID's, see section 3.1.1 Client ID. Server ID is
658 64 bit Server ID based on IPv4 addresses:
660 32 bit IP address of the server
664 160 bit Server ID based on IPv6 addresses:
666 128 bit IP address of the server
670 o IP address of the server - This is the real IP address of
673 o Port - This is the port the server is bound to.
675 o Random number - This is used to further randomize the Server ID.
678 Collisions are not expected to happen in any conditions. The Server ID
679 is always created by the server itself and server is responsible of
680 distributing it to the router.
684 3.2.3 SILC Server Ports
686 The following ports has been assigned by IANA for the SILC protocol:
693 If there are needs to create new SILC networks in the future the port
694 numbers must be officially assigned by the IANA.
696 Server on network above privileged ports (>1023) should not be trusted
697 as they could have been set up by untrusted party.
703 Router server in SILC network is responsible for keeping the cell together
704 and routing messages to other servers and to other routers. Router server
705 is also a normal server thus clients may connect to it as it would be
706 just normal SILC server.
708 However, router servers has a lot of important tasks that normal servers
709 do not have. Router server knows everything about everything in the SILC.
710 They know all clients currently on SILC, all servers and routers and all
711 channels in SILC. Routers are the only servers in SILC that care about
712 global information and keeping them up to date at all time. And, this
713 is what they must do.
717 3.3.1 Router's Local ID List
719 Router server as well must keep local list of connected clients and
720 locally created channels. However, this list is extended to include all
721 the informations of the entire cell, not just the server itself as for
724 However, on router this list is a lot smaller since routers do not keep
725 information about user's nickname, username and hostname and real name
726 since these are not needed by the router. Router keeps only information
730 Hence, local list for router includes:
733 server list - All servers in the cell
740 client list - All clients in the cell
744 channel list - All channels in the cell
746 o Client ID's on channel
747 o Client ID modes on channel
752 Note that locally connected clients and other information include all the
753 same information as defined in section section 3.2.1 Server's Local ID
758 3.3.2 Router's Global ID List
760 Router server must also keep global list. Normal servers do not have
761 global list as they know only about local information. Global list
762 includes all the clients on SILC, their Client ID's, all created channels
763 and their Channel ID's and all servers and routers on SILC and their
764 Server ID's. That is said, global list is for global information and the
765 list must not include the local information already on the router's local
768 Note that the global list does not include information like nicknames,
769 usernames and hostnames or user's real names. Router does not keep
770 these informations as they are not needed by the router. This
771 information is available from the client's server which maybe queried
774 Hence, global list includes:
777 server list - All servers in SILC
783 client list - All clients in SILC
786 channel list - All channels in SILC
788 o Client ID's on channel
789 o Client ID modes on channel
794 3.3.3 Router's Server ID
796 Router's Server ID's are equivalent to normal Server ID's. As routers
797 are normal servers as well same types of ID's applies for routers as well.
798 Thus, see section 3.2.2 Server ID. Server ID's for routers are always
799 created by the remote router where the router is connected to.
805 A channel is a named group of one or more clients which will all receive
806 messages addressed to that channel. The channel is created when first
807 client requests JOIN command to the channel, and the channel ceases to
808 exist when the last client has left it. When channel exists, any client
809 can reference it using the name of the channel.
811 Channel names are unique although the real uniqueness comes from 64 bit
812 Channel ID that unifies each channel. However, channel names are still
813 unique and no two global channels with same name may exist. The Channel
814 name is a string of maximum length of 256 characters. Channel names may
815 not contain any spaces (` '), any non-printable ASCII characters,
816 commas (`,') and wildcard characters.
818 Channels can have operators that can administrate the channel and
819 operate all of its modes. The following operators on channel exist on SILC
823 o Channel founder - When channel is created the joining client becomes
824 channel founder. Channel founder is channel operator with some more
825 privileges. Basically, channel founder can fully operate the channel
826 and all of its modes. The privileges are limited only to the particular
827 channel. There can be only one channel founder per channel. Channel
828 founder supersedes channel operator's privileges.
830 Channel founder privileges cannot be removed by any other operator on
831 channel. When channel founder leaves the channel there is no channel
832 founder on the channel. Channel founder also cannot be removed by
833 force from the channel.
835 o Channel operator - When client joins to channel that has not existed
836 previously it will become automatically channel operator (and channel
837 founder discussed above). Channel operator is able administrate the
838 channel, set some modes on channel, remove a badly behaving client from
839 the channel and promote other clients to become channel operator.
840 The privileges are limited only to the particular channel.
842 Normal channel user may be promoted (opped) to channel operator
843 gaining channel operator privileges. Channel founder or other channel
844 operator may also demote (deop) channel operator to normal channel
852 Channels are distinguished from other channels by unique Channel ID.
853 The Channel ID is a 64 bit ID (for IPv4) or 160 bit ID (for IPv6), and
854 collisions are not expected to happen in any conditions. Channel names
855 are just for logical use of channels. The Channel ID is created by the
856 server where the channel is created. The Channel ID is defined as
860 64 bit Channel ID based on IPv4 addresses:
862 32 bit Router's Server ID IP address (bits 1-32)
863 16 bit Router's Server ID port (bits 33-48)
866 160 bit Channel ID based on IPv6 addresses:
868 128 bit Router's Server ID IP address (bits 1-128)
869 16 bit Router's Server ID port (bits 129-144)
872 o Router's Server ID IP address - Indicates the IP address of
873 the router of the cell where this channel is created. This is
874 taken from the router's Server ID. This way SILC router knows
875 where this channel resides in the SILC network.
877 o Router's Server ID port - Indicates the port of the channel on
878 the server. This is taken from the router's Server ID.
880 o Random number - To further randomize the Channel ID. This makes
881 sure that there are no collisions. This also means that
882 in a cell there can be 2^16 channels.
889 Operators are normal users with extra privileges to their server or
890 router. Usually these people are SILC server and router administrators
891 that take care of their own server and clients on them. The purpose of
892 operators is to administrate the SILC server or router. However, even
893 an operator with highest privileges is not able to enter invite-only
894 channel, to gain access to the contents of a encrypted and authenticated
895 packets traveling in the SILC network or to gain channel operator
896 privileges on public channels without being promoted. They have the
897 same privileges as everyone else except they are able to administrate
898 their server or router.
904 Commands are very important part on SILC network especially for client
905 which uses commands to operate on the SILC network. Commands are used
906 to set nickname, join to channel, change modes and many other things.
908 Client usually sends the commands and server replies by sending a reply
909 packet to the command. Server may also send commands usually to serve
910 the original client's request. However, server may not send command
911 to client and there are some commands that server must not send.
913 Note that the command reply is usually sent only after client has sent
914 the command request but server is allowed to send command reply packet
915 to client even if client has not requested the command. Client may,
916 however, choose ignore the command reply, but should not.
918 It is expected that some of the commands may be miss-used by clients
919 resulting various problems on the server side. Every implementation
920 should assure that commands may not be executed more than once, say,
921 in two (2) seconds. However, to keep response rate up, allowing for
922 example five (5) commands before limiting is allowed. It is recommended
923 that commands such as SILC_COMMAND_NICK, SILC_COMMAND_JOIN and
924 SILC_COMMAND_LEAVE should be limited in all cases as they require
925 heavy operations. This should be sufficient to prevent the miss-use of
928 SILC commands are described in section 5 SILC Commands.
934 Packets are naturally the most important part of the protocol and the
935 packets are what actually makes the protocol. Packets in SILC network
936 are always encrypted using, usually, the shared secret session key
937 or some other key, for example, channel key, when encrypting channel
938 messages. The SILC Packet Protocol is a wide protocol and is described
939 in [SILC2]. This document does not define or describe details of
945 3.8 Packet Encryption
947 All packets passed in SILC network must be encrypted. This section
948 defines how packets must be encrypted in the SILC network. The detailed
949 description of the actual encryption process of the packets are
950 described in [SILC2].
952 Client and its server shares secret symmetric session key which is
953 established by the SILC Key Exchange Protocol, described in [SILC3].
954 Every packet sent from client to server, with exception of packets for
955 channels, are encrypted with this session key.
957 Channels has their own key that are shared by every client on the channel.
958 However, the channel keys are cell specific thus one cell does not know
959 the channel key of the other cell, even if that key is for same channel.
960 Channel key is also known by the routers and all servers that has clients
961 on the channel. However, channels may have channel private keys that
962 are entirely local setting for client. All clients on the channel must
963 know the channel private key before hand to be able to talk on the
964 channel. In this case, no server or router knows the key for channel.
966 Server shares secret symmetric session key with router which is
967 established by the SILC Key Exchange Protocol. Every packet passed from
968 server to router, with exception of packets for channels, are encrypted
969 with the shared session key. Same way, router server shares secret
970 symmetric key with its primary route. However, every packet passed
971 from router to other router, including packets for channels, are
972 encrypted with the shared session key. Every router connection has
973 their own session keys.
977 3.8.1 Determination of the Source and the Destination
979 The source and the destination of the packet needs to be determined
980 to be able to route the packets to correct receiver. This information
981 is available in the SILC Packet Header which is included in all packets
982 sent in SILC network. The SILC Packet Header is described in [SILC2].
984 The header is always encrypted with the session key who is next receiver
985 of the packet along the route. The receiver of the packet, for example
986 a router along the route, is able to determine the sender and the
987 destination of the packet by decrypting the SILC Packet Header and
988 checking the ID's attached to the header. The ID's in the header will
989 tell to where the packet needs to be sent and where it is coming from.
991 The header in the packet does not change during the routing of the
992 packet. The original sender, for example client, assembles the packet
993 and the packet header and server or router between the sender and the
994 receiver must not change the packet header.
996 Note that the packet and the packet header may be encrypted with
997 different keys. For example, packets to channels are encrypted with
998 the channel key, however, the header is encrypted with the session key
999 as described above. However, the header and the packet may be encrypted
1000 with same key. This is case, for example, with command packets.
1004 3.8.2 Client To Client
1006 Process of message delivery and encryption from client to another
1007 client is as follows.
1009 Example: Private message from client to another client on different
1010 servers. Clients do not share private message delivery
1011 keys; normal session keys are used.
1013 o Client 1. sends encrypted packet to its server. The packet is
1014 encrypted with the session key shared between client and its
1017 o Server determines the destination of the packet and decrypts
1018 the packet. Server encrypts the packet with session key shared
1019 between the server and its router, and sends the packet to the
1022 o Router determines the destination of the packet and decrypts
1023 the packet. Router encrypts the packet with session key
1024 shared between the router and the destination server, and sends
1025 the packet to the server.
1027 o Server determines the client to which the packet is destined
1028 to and decrypts the packet. Server encrypts the packet with
1029 session key shared between the server and the destination client,
1030 and sends the packet to the client.
1032 o Client 2. decrypts the packet.
1035 Example: Private message from client to another client on different
1036 servers. Clients has established secret shared private
1037 message delivery key with each other and that is used in
1038 the message encryption.
1040 o Client 1. sends encrypted packet to its server. The packet is
1041 encrypted with the private message delivery key shared between
1044 o Server determines the destination of the packet and sends the
1045 packet to the router.
1047 o Router determines the destination of the packet and sends the
1048 packet to the server.
1050 o Server determines the client to which the packet is destined
1051 to and sends the packet to the client.
1053 o Client 2. decrypts the packet with the secret shared key.
1056 If clients share secret key with each other the private message
1057 delivery is much simpler since servers and routers between the
1058 clients do not need to decrypt and re-encrypt the packet.
1060 The process for clients on same server is much simpler as there are
1061 no need to send the packet to the router. The process for clients
1062 on different cells is same as above except that the packet is routed
1063 outside the cell. The router of the destination cell routes the
1064 packet to the destination same way as described above.
1068 3.8.3 Client To Channel
1070 Process of message delivery from client on channel to all the clients
1073 Example: Channel of four users; two on same server, other two on
1074 different cells. Client sends message to the channel.
1076 o Client 1. encrypts the packet with channel key and sends the
1077 packet to its server.
1079 o Server determines local clients on the channel and sends the
1080 packet to the Client on the same server. Server then sends
1081 the packet to its router for further routing.
1083 o Router determines local clients on the channel, if found
1084 sends packet to the local clients. Router determines global
1085 clients on the channel and sends the packet to its primary
1086 router or fastest route.
1088 o (Other router(s) do the same thing and sends the packet to
1091 o Server determines local clients on the channel and sends the
1092 packet to the client.
1094 o All clients receiving the packet decrypts the packet.
1098 3.8.4 Server To Server
1100 Server to server packet delivery and encryption is described in above
1101 examples. Router to router packet delivery is analogous to server to
1102 server. However, some packets, such as channel packets, are processed
1103 differently. These cases are described later in this document and
1104 more in detail in [SILC2].
1108 3.9 Key Exchange And Authentication
1110 Key exchange is done always when for example client connects to server
1111 but also when server and router and router and router connects to each
1112 other. The purpose of key exchange protocol is to provide secure key
1113 material to be used in the communication. The key material is used to
1114 derive various security parameters used to secure SILC packets. The
1115 SILC Key Exchange protocol is described in detail in [SILC3].
1117 Authentication is done after key exchange protocol has been successfully
1118 completed. The purpose of authentication is to authenticate for example
1119 client connecting to the server. However, Usually clients are accepted
1120 to connect to server without explicit authentication. Servers are
1121 required use authentication protocol when connecting. The authentication
1122 may be based on passphrase (pre-shared-secret) or public key. The
1123 connection authentication protocol is described in detail in [SILC3].
1127 3.9.1 Authentication Payload
1129 Authentication payload is used separately from the SKE and the Connection
1130 authentication protocol. It is used during the session to authenticate
1131 with the remote. For example, the client can authenticate itself to the
1132 server to be server operator. In this case, Authentication Payload is
1135 The format of the Authentication Payload is as follows:
1141 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
1142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1143 | Payload Length | Authentication Method |
1144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1145 | Public Data Length | |
1146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1151 | Authentication Data Length | |
1152 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1154 ~ Authentication Data ~
1156 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|
1160 Figure 5: Authentication Payload
1164 o Payload Length (2 bytes) - Length of the entire payload.
1166 o Authentication Type (2) - The method of the authentication.
1167 The authentication methods are defined in [SILC2] in the
1168 Connection Auth Request Payload. The NONE authentication
1169 method is not recommended.
1171 o Public Data Length (2 bytes) - Indicates the length of
1172 the Public Data field.
1174 o Public Data (variable length) - This is defined only if
1175 the authentication method is public key. If it is any other
1176 this field does not exist and the Public Data Length field
1179 When the authentication method is public key this includes
1180 128 to 4096 bytes of non-zero random data that is used in
1181 the signature process, described subsequently.
1183 o Authentication Data Length (2 bytes) - Indicates the
1184 length of the Authentication Data field.
1186 o Authentication Data (variable length) - Authentication
1187 method dependent authentication data.
1191 If the authentication method is password based, the Authentication
1192 Data field includes the plaintext password. It is safe to send
1193 plaintext password since the entire payload is encrypted. In this
1194 case the Public Data Lenght is set to zero (0).
1196 If the authentication method is public key based (or certificate)
1197 the Authentication Data is computed as follows:
1199 HASH = hash(random bytes | ID | public key (or certificate));
1200 Authentication Data = sign(HASH);
1202 The hash() and the sign() are the hash funtion and the public key
1203 cryptography function selected in the SKE protocol. The public key
1204 is SILC style public key unless certificates are used. The ID is the
1205 entity's ID (Client or Server ID) who is authenticating itself. The ID
1206 is raw ID data. The random bytes are non-zero random bytes of length
1207 between 128 and 4096 bytes, and will be included into the Public Data
1210 The receiver will compute the signature using the random data received
1211 in the payload, the ID associated to the connection and the public key
1212 (or certificate) received in the SKE protocol. After computing the
1213 receiver must verify the signature. In this case also, the entire
1214 payload is encrypted.
1220 This section defines all the allowed algorithms that can be used in
1221 the SILC protocol. This includes mandatory cipher, mandatory public
1222 key algorithm and MAC algorithms.
1228 Cipher is the encryption algorithm that is used to protect the data
1229 in the SILC packets. See [SILC2] of the actual encryption process and
1230 definition of how it must be done. SILC has a mandatory algorithm that
1231 must be supported in order to be compliant with this protocol.
1233 The following ciphers are defined in SILC protocol:
1236 aes-256-cbc AES in CBC mode, 256 bit key (mandatory)
1237 aes-192-cbc AES in CBC mode, 192 bit key (optional)
1238 aes-128-cbc AES in CBC mode, 128 bit key (optional)
1239 twofish-256-cbc Twofish in CBC mode, 256 bit key (optional)
1240 twofish-192-cbc Twofish in CBC mode, 192 bit key (optional)
1241 twofish-128-cbc Twofish in CBC mode, 128 bit key (optional)
1242 blowfish-128-cbc Blowfish in CBC mode, 128 bit key (optional)
1243 cast-256-cbc CAST-256 in CBC mode, 256 bit key (optional)
1244 cast-192-cbc CAST-256 in CBC mode, 192 bit key (optional)
1245 cast-128-cbc CAST-256 in CBC mode, 128 bit key (optional)
1246 rc6-256-cbc RC6 in CBC mode, 256 bit key (optional)
1247 rc6-192-cbc RC6 in CBC mode, 192 bit key (optional)
1248 rc6-128-cbc RC6 in CBC mode, 128 bit key (optional)
1249 mars-256-cbc Mars in CBC mode, 256 bit key (optional)
1250 mars-192-cbc Mars in CBC mode, 192 bit key (optional)
1251 mars-128-cbc Mars in CBC mode, 128 bit key (optional)
1252 none No encryption (optional)
1256 Algorithm none does not perform any encryption process at all and
1257 thus is not recommended to be used. It is recommended that no client
1258 or server implementation would accept none algorithms except in special
1261 Additional ciphers may be defined to be used in SILC by using the
1262 same name format as above.
1266 3.10.2 Public Key Algorithms
1268 Public keys are used in SILC to authenticate entities in SILC network
1269 and to perform other tasks related to public key cryptography. The
1270 public keys are also used in the SILC Key Exchange protocol [SILC3].
1272 The following public key algorithms are defined in SILC protocol:
1279 DSS is described in [Menezes]. The RSA must be implemented according
1280 PKCS #1 [PKCS1]. The mandatory PKCS #1 implementation in SILC must be
1281 compliant to either PKCS #1 version 1.5 or newer with the the following
1282 notes: The signature encoding is always in same format as the encryption
1283 encoding regardles of the PKCS #1 version. The signature with appendix
1284 (with hash algorithm OID in the data) must not be used in the SILC. The
1285 rationale for this is that there is no binding between the PKCS #1 OIDs
1286 and the hash algorithms used in the SILC protocol. Hence, the encoding
1287 is always in PKCS #1 version 1.5 format.
1289 Additional public key algorithms may be defined to be used in SILC.
1293 3.10.3 Hash Functions
1295 Hash functions are used as part of MAC algorithms defined in the next
1296 section. They are also used in the SILC Key Exchange protocol defined
1299 The following Hash algorithm are defined in SILC protocol:
1301 sha1 SHA-1, length = 20 (mandatory)
1302 md5 MD5, length = 16 (optional)
1306 3.10.4 MAC Algorithms
1308 Data integrity is protected by computing a message authentication code
1309 (MAC) of the packet data. See [SILC2] for details how to compute the
1312 The following MAC algorithms are defined in SILC protocol:
1315 hmac-sha1-96 HMAC-SHA1, length = 12 (mandatory)
1316 hmac-md5-96 HMAC-MD5, length = 12 (optional)
1317 hmac-sha1 HMAC-SHA1, length = 20 (optional)
1318 hmac-md5 HMAC-MD5, length = 16 (optional)
1319 none No MAC (optional)
1322 The none MAC is not recommended to be used as the packet is not
1323 authenticated when MAC is not computed. It is recommended that no
1324 client or server would accept none MAC except in special debugging
1327 The HMAC algorithm is described in [HMAC] and hash algorithms that
1328 are used as part of the HMACs are described in [Scheneir] and in
1331 Additional MAC algorithms may be defined to be used in SILC.
1335 3.10.5 Compression Algorithms
1337 SILC protocol supports compression that may be applied to unencrypted
1338 data. It is recommended to use compression on slow links as it may
1339 significantly speed up the data transmission. By default, SILC does not
1340 use compression which is the mode that must be supported by all SILC
1343 The following compression algorithms are defined:
1346 none No compression (mandatory)
1347 zlib GNU ZLIB (LZ77) compression (optional)
1350 Additional compression algorithms may be defined to be used in SILC.
1354 3.11 SILC Public Key
1356 This section defines the type and format of the SILC public key. All
1357 implementations must support this public key type. See [SILC3] for
1358 other optional public key and certificate types allowed in SILC
1359 protocol. Public keys in SILC may be used to authenticate entities
1360 and to perform other tasks related to public key cryptography.
1362 The format of the SILC Public Key is as follows:
1368 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
1369 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1370 | Public Key Length |
1371 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1372 | Algorithm Name Length | |
1373 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1377 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1378 | Identifier Length | |
1379 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1383 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1387 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1391 Figure 5: SILC Public Key
1395 o Public Key Length (4 bytes) - Indicates the full length
1396 of the public key, not including this field.
1398 o Algorithm Name Length (2 bytes) - Indicates the length
1399 of the Algorithm Length field, not including this field.
1401 o Algorithm name (variable length) - Indicates the name
1402 of the public key algorithm that the key is. See the
1403 section 3.10.2 Public Key Algorithms for defined names.
1405 o Identifier Length (2 bytes) - Indicates the length of
1406 the Identifier field, not including this field.
1408 o Identifier (variable length) - Indicates the identifier
1409 of the public key. This data can be used to identify
1410 the owner of the key. The identifier is of the following
1414 HN Host name or IP address
1421 Examples of an identifier:
1423 `UN=priikone, HN=poseidon.pspt.fi, E=priikone@poseidon.pspt.fi'
1425 `UN=sam, HN=dummy.fi, RN=Sammy Sam, O=Company XYZ, C=Finland'
1427 At least user name (UN) and host name (HN) must be provided as
1428 identifier. The fields are separated by commas (`,'). If
1429 comma is in the identifier string it must be written as `\\,',
1430 for example, `O=Company XYZ\\, Inc.'.
1432 o Public Data (variable length) - Includes the actual
1433 public data of the public key.
1435 The format of this field for RSA algorithm is
1444 The format of this field for DSS algorithm is
1456 The variable length fields are multiple precession
1457 integers encoded as strings in both examples.
1459 Other algorithms must define their own type of this
1460 field if they are used.
1463 All fields in the public key are in MSB (most significant byte first)
1468 3.12 SILC Version Detection
1470 The version detection of both client and server is performed at the
1471 connection phase while executing the SILC Key Exchange protocol. The
1472 version identifier is exchanged between initiator and responder. The
1473 version identifier is of the following format:
1476 SILC-<protocol version>-<software version>
1479 The version strings are of the following format:
1482 protocol version = <major>.<minor>
1483 software version = <major>[.<minor>[.<build>]]
1486 Protocol version may provide both major and minor version. Currently
1487 implementations must set the protocol version and accept the protocol
1488 version as SILC-1.0-<sotware version>.
1490 Software version may provide major, minor and build version. The
1491 software version may be freely set and accepted.
1494 Thus, the version string could be, for example:
1504 This section describes various SILC procedures such as how the
1505 connections are created and registered, how channels are created and
1506 so on. The section describes the procedures only generally as details
1507 are described in [SILC2] and [SILC3].
1511 4.1 Creating Client Connection
1513 This section describes the procedure when client connects to SILC server.
1514 When client connects to server the server must perform IP address lookup
1515 and reverse IP address lookup to assure that the origin host really is
1516 who it claims to be. Client, host, connecting to server must have
1517 both valid IP address and fully qualified domain name (FQDN).
1519 After that the client and server performs SILC Key Exchange protocol
1520 which will provide the key material used later in the communication.
1521 The key exchange protocol must be completed successfully before the
1522 connection registration may continue. The SILC Key Exchange protocol
1523 is described in [SILC3].
1525 Typical server implementation would keep a list of connections that it
1526 allows to connect to the server. The implementation would check, for
1527 example, the connecting client's IP address from the connection list
1528 before the SILC Key Exchange protocol has been started. Reason for
1529 this is that if the host is not allowed to connect to the server there
1530 is no reason to perform a key exchange protocol.
1532 After successful key exchange protocol the client and server performs
1533 connection authentication protocol. The purpose of the protocol is to
1534 authenticate the client connecting to the server. Flexible
1535 implementation could also accept the client to connect to the server
1536 without explicit authentication. However, if authentication is
1537 desired for a specific client it may be based on passphrase or
1538 public key authentication. If authentication fails the connection
1539 must be terminated. The connection authentication protocol is described
1542 After successful key exchange and authentication protocol the client
1543 registers itself by sending SILC_PACKET_NEW_CLIENT packet to the
1544 server. This packet includes various information about the client
1545 that the server uses to create the client. Server creates the client
1546 and sends SILC_PACKET_NEW_ID to the client which includes the created
1547 Client ID that the client must start using after that. After that
1548 all SILC packets from the client must have the Client ID as the
1549 Source ID in the SILC Packet Header, described in [SILC2].
1551 Client must also get the server's Server ID that is to be used as
1552 Destination ID in the SILC Packet Header when communicating with
1553 the server (for example when sending commands to the server). The
1554 ID may be resolved in two ways. Client can take the ID from an
1555 previously received packet from server that must include the ID,
1556 or to send SILC_COMMAND_INFO command and receive the Server ID as
1559 Server may choose not to use the information received in the
1560 SILC_PACKET_NEW_CLIENT packet. For example, if public key or
1561 certificate were used in the authentication, server may use those
1562 informations rather than what it received from client. This is suitable
1563 way to get the true information about client if it is available.
1565 The nickname of client is initially set to the username sent in the
1566 SILC_PACKET_NEW_CLIENT packet. User should set the nickname to more
1567 suitable by sending SILC_COMMAND_NICK command. However, this is not
1568 required as part of registration process.
1570 Server must also distribute the information about newly registered
1571 client to its router (or if the server is router, to all routers in
1572 the SILC network). More information about this in [SILC2].
1576 4.2 Creating Server Connection
1578 This section descibres the procedure when server connects to its
1579 router (or when router connects to other router, the cases are
1580 equivalent). The procedure is very much alike when client connects
1581 to the server thus it is not repeated here.
1583 One difference is that server must perform connection authentication
1584 protocol with proper authentication. Proper authentication is based
1585 on passphrase or public key authentication.
1587 After server and router has successfully performed the key exchange
1588 and connection authentication protocol, the server register itself
1589 to the router by sending SILC_PACKET_NEW_SERVER packet. This packet
1590 includes the server's Server ID that it has created by itself and
1591 other relevant information about the server.
1593 After router has received the SILC_PACKET_NEW_SERVER packet it
1594 distributes the information about newly registered server to all routers
1595 in the SILC network. More information about this in [SILC2].
1597 As client needed to resolve the destination ID this must be done by the
1598 server that connected to the router, as well. The way to resolve it is
1599 to get the ID from previously received packet. Server must also start
1600 using its own Server ID as Source ID in SILC Packet Header and the
1601 router's Server ID as Destination when communicating with the router.
1603 If the server has already connected clients and locally created
1604 channels the server must distribute these informations to the router.
1605 The distribution is done by sending packet SILC_PACKET_NEW_CHANNEL.
1606 See [SILC2] for more information on this.
1610 4.3 Joining to a Channel
1612 This section describes the procedure when client joins to a channel.
1613 Client may join to channel by sending command SILC_COMMAND_JOIN to the
1614 server. If the receiver receiving join command is normal server the
1615 server must check its local list whether this channel already exists
1616 locally. This would indicate that some client connected to the server
1617 has already joined to the channel. If this is case the client is
1618 joined to the client, new channel key is created and information about
1619 newly joined channel is sent to the router. The router is informed
1620 by sending SILC_NOTIFY_TYPE_JOIN notify type. The notify type must
1621 also be sent to the local clients on the channel. The new channel key
1622 is also sent to the router and to local clients on the channel.
1624 If the channel does not exist in the local list the client's command
1625 must be sent to the router which will then perform the actual joining
1626 procedure. When server receives the reply to the command from the
1627 router it must be sent to the client who sent the command originally.
1628 Server will also receive the channel key from the server that it must
1629 send to the client who originally requested the join command. The server
1630 must also save the channel key.
1632 If the receiver of the join command is router it must first check its
1633 local list whether anyone in the cell has already joined to the channel.
1634 If this is the case the client is joined to the channel and reply is
1635 sent to the client. If the command was sent by server the command reply
1636 is sent to the server who sent it. Then the router must also create
1637 new channel key and distribute it to all clients on the channel and
1638 all servers that has clients on the channel. Router must also send
1639 the SILC_NOTIFY_TYPE_JOIN notify type to local clients on the channel
1640 and to local servers that has clients on the channel.
1642 If the channel does not exist on the router's local list it must
1643 check the global list whether the channel exists at all. If it does
1644 the client is joined to the channel as described previously. If
1645 the channel does not exist the channel is created and the client
1646 is joined to the channel. The channel key is also created and
1647 distributed as previously described. The client joining to the created
1648 channel is made automatically channel founder and both channel founder
1649 and channel operator privileges is set for the client.
1651 If the router created the channel in the process, information about the
1652 new channel must be broadcasted to all routers. This is done by
1653 broadcasting SILC_PACKET_NEW_CHANNEL packet to the router's primary
1654 route. When the router joins the client to the channel it must also
1655 send information about newly joined client to all routers in the SILC
1656 network. This is done by broadcasting the SILC_NOTIFY_TYPE_JOIN notify
1657 type to the router's primary route.
1659 It is important to note that new channel key is created always when
1660 new client joins to channel, whether the channel has existed previously
1661 or not. This way the new client on the channel is not able to decrypt
1662 any of the old traffic on the channel. Client who receives the reply to
1663 the join command must start using the received Channel ID in the channel
1664 message communication thereafter. Client also receives the key for the
1665 channel in the command reply.
1669 4.4 Channel Key Generation
1671 Channel keys are created by router who creates the channel by taking
1672 enough randomness from cryptographically strong random number generator.
1673 The key is generated always when channel is created, when new client
1674 joins a channel and after the key has expired. Key could expire for
1677 The key must also be re-generated whenever some client leaves a channel.
1678 In this case the key is created from scratch by taking enough randomness
1679 from the random number generator. After that the key is distributed to
1680 all clients on the channel. However, channel keys are cell specific thus
1681 the key is created only on the cell where the client, who left the
1682 channel, exists. While the server or router is creating the new channel
1683 key, no other client may join to the channel. Messages that are sent
1684 while creating the new key are still processed with the old key. After
1685 server has sent the SILC_PACKET_CHANNEL_KEY packet must client start
1686 using the new key. If server creates the new key the server must also
1687 send the new key to its router. See [SILC2] on more information about
1688 how channel messages must be encrypted and decrypted when router is
1691 When client receives the SILC_PACKET_CHANNEL_KEY packet with the
1692 Channel Key Payload it must process the key data to create encryption
1693 and decryption key, and to create the HMAC key that is used to compute
1694 the MACs of the channel messages. The processing is as follows:
1696 channel_key = raw key data
1697 HMAC key = hash(raw key data)
1699 The raw key data is the key data received in the Channel Key Payload.
1700 The hash() function is the hash function used in the HMAC of the channel.
1704 4.5 Private Message Sending and Reception
1706 Private messages are sent point to point. Client explicitly destines
1707 a private message to specific client that is delivered to only to that
1708 client. No other client may receive the private message. The receiver
1709 of the private message is destined in the SILC Packet Header as any
1710 other packet as well.
1712 If the sender of a private message does not know the receiver's Client
1713 ID, it must resolve it from server. There are two ways to resolve the
1714 client ID from server; it is recommended that client implementations
1715 send SILC_COMMAND_IDENTIFY command to receive the Client ID. Client
1716 may also send SILC_COMMAND_WHOIS command to receive the Client ID.
1717 If the sender has received earlier a private message from the receiver
1718 it should have cached the Client ID from the SILC Packet Header.
1720 Receiver of a private message should not explicitly trust the nickname
1721 that it receives in the Private Message Payload, described in [SILC2].
1722 Implementations could resolve the nickname from server, as described
1723 previously, and compare the received Client ID and the SILC Packet
1724 Header's Client ID. The nickname in the payload is merely provided
1725 to be displayed for end user.
1727 See [SILC2] for description of private message encryption and decryption
1732 4.6 Private Message Key Generation
1734 Private message may be protected by key generated by client. The key
1735 may be generated and sent to the other client by sending packet
1736 SILC_PACKET_PRIVATE_MESSAGE_KEY which travels through the network
1737 and is secured by session keys. After that the private message key
1738 is used in the private message communication between those clients.
1740 Other choice is to entirely use keys that are not sent through
1741 the SILC network at all. This significantly adds security. This key
1742 would be pre-shared-key that is known by both of the clients. Both
1743 agree about using the key and starts sending packets that indicate
1744 that the private message is secured using private message key.
1746 The key material used as private message key is implementation issue.
1747 However, SILC_PACKET_KEY_AGREEMENT packet may be used to negotiate
1748 the key material. If the key is normal pre-shared-key or randomly
1749 generated key, and the SILC_PACKET_KEY_AGREEMENT was not used, then
1750 the key material should be processed as defined in the [SILC3]. In
1751 the processing, however, the HASH, as defined in [SILC3] must be
1752 ignored. After processing the key material it is employed as defined
1753 in [SILC3], however, the HMAC key material must be discarded.
1755 If the key is pre-shared-key or randomly generated the implementations
1756 should use the SILC protocol's mandatory cipher as the cipher. If the
1757 SKE was used to negotiate key material the cipher was negotiated as well.
1760 4.7 Channel Message Sending and Reception
1762 Channel messages are delivered to group of users. The group forms a
1763 channel and all clients on the channel receives messages sent to the
1766 Channel messages are destined to channel by specifying the Channel ID
1767 as Destination ID in the SILC Packet Header. The server must then
1768 distribute the message to all clients on the channel by sending the
1769 channel message destined explicitly to a client on the channel.
1771 See [SILC2] for description of channel message encryption and decryption
1776 4.8 Session Key Regeneration
1778 Session keys should be regenerated periodically, say, once in an hour.
1779 The re-key process is started by sending SILC_PACKET_REKEY packet to
1780 other end, to indicate that re-key must be performed. The initiator
1781 of the connection should perform the re-key.
1783 If perfect forward secrecy (PFS) flag was selected in the SILC Key
1784 Exchange protocol [SILC3] the re-key must cause new key exchange with
1785 SKE protocol. In this case the protocol is secured with the old key
1786 and the protocol results to new key material. See [SILC3] for more
1787 information. After the SILC_PACKET_REKEY packet is sent the sender
1788 will perform the SKE protocol.
1790 If PFS flag was set the resulted key material is processed as described
1791 in the section Processing the Key Material in [SILC3]. The difference
1792 with re-key in the processing is that the initial data for the hash
1793 function is just the resulted key material and not the HASH as it
1794 is not computed at all with re-key. Other than that, the key processing
1795 it equivalent to normal SKE negotiation.
1797 If PFS flag was not set, which is the default case, then re-key is done
1798 without executing SKE protocol. In this case, the new key is created by
1799 providing the current sending encryption key to the SKE protocol's key
1800 processing function. The process is described in the section Processing
1801 the Key Material in [SILC3]. The difference in the processing is that
1802 the initial data for the hash function is the current sending encryption
1803 key and not the SKE's KEY and HASH values. Other than that, the key
1804 processing is equivalent to normal SKE negotiation.
1806 After both parties has regenerated the session key, both send
1807 SILC_PACKET_REKEY_DONE packet to each other. These packets are still
1808 secured with the old key. After these packets, the subsequent packets
1809 must be protected with the new key.
1813 4.9 Command Sending and Reception
1815 Client usually sends the commands in the SILC network. In this case
1816 the client simply sends the command packet to server and the server
1817 processes it and replies with command reply packet.
1819 However, if the server is not able to process the command, it is sent
1820 to the server's router. This is case for example with commands such
1821 as, SILC_COMMAND_JOIN and SILC_COMMAND_WHOIS commands. However, there
1822 are other commands as well. For example, if client sends the WHOIS
1823 command requesting specific information about some client the server must
1824 send the WHOIS command to router so that all clients in SILC network
1825 are searched. The router, on the other hand, sends the WHOIS command
1826 further to receive the exact information about the requested client.
1827 The WHOIS command travels all the way to the server who owns the client
1828 and it replies with command reply packet. Finally, the server who
1829 sent the command receives the command reply and it must be able to
1830 determine which client sent the original command. The server then
1831 sends command reply to the client. Implementations should have some
1832 kind of cache to handle, for example, WHOIS information. Servers
1833 and routers along the route could all cache the information for faster
1834 referencing in the future.
1836 The commands sent by server may be sent hop by hop until someone is able
1837 to process the command. However, it is preferred to destine the command
1838 as precisely as it is possible. In this case, other routers en route
1839 must route the command packet by checking the true sender and true
1840 destination of the packet. However, servers and routers must not route
1841 command reply packets to clients coming from other server. Client
1842 must not accept command reply packet originated from anyone else but
1843 from its own server.
1850 5.1 SILC Commands Syntax
1852 This section briefly describes the syntax of the command notions
1853 in this document. Every field in command is separated from each
1854 other by whitespaces (` ') indicating that each field is independent
1855 argument and each argument must have own Command Argument Payload.
1856 The number of maximum arguments are defined with each command
1857 separately. The Command Argument Payload is described in [SILC2].
1859 Every command defines specific number for each argument. Currently,
1860 they are defined in ascending order; first argument has number one
1861 (1), second has number two (2) and so on. This number is set into the
1862 Argument Type field in the Command Argument Payload. This makes it
1863 possible to send the arguments in free order as the number must be
1864 used to identify the type of the argument. This makes is it also
1865 possible to have multiple optional arguments in commands and in
1866 command replies. The number of argument is marked in parentheses
1867 before the actual argument.
1872 Example: Arguments: (1) <nickname> (2) <username@host>
1876 Every command replies with Status Payload. This payload tells the
1877 sender of the command whether the command was completed successfully or
1878 whether there was an error. If error occured the payload includes the
1879 error type. In the next section the Status Payload is not described
1880 as it is common to all commands and has been described here. Commands
1881 may reply with other arguments as well. These arguments are command
1882 specific and are described in the next section.
1891 Arguments: (1) <nickname>[@<server>] (2) <message>
1894 The command has maximum of 3 arguments. However, only first
1895 and second arguments are mandatory.
1897 First argument <nickname> is mandatory but may have optional
1898 <nickname@server> format as well. Second argument is mandatory
1899 <message> argument. Third argument is optional <count> argument.
1901 The numbers in parentheses are the argument specific numbers
1902 that specify the type of the argument in Command Argument Payload.
1903 The receiver always knows that, say, argument number two (2) is
1904 <message> argument, regardless of the ordering of the arguments in
1905 the Command Payload.
1907 Reply messages to the command:
1910 Arguments: (1) <Status Payload> (2) [<channel list>]
1911 (3) <idle time> (4) [<away message>]
1913 This command may reply with maximum of 4 arguments. However,
1914 only the first and third arguments are mandatory. The numbers
1915 in the parentheses have the same meaning as in the upper
1916 command sending specification.
1918 Every command reply with <Status Payload>, it is mandatory
1919 argument for all command replies and for this reason it is not
1920 described in the command reply descriptions.
1927 SILC_STATUS_ERR_TOO_MANY_TARGETS
1928 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1929 SILC_STATUS_ERR_NO_SUCH_NICK
1931 Every command reply also defines set of status message that it
1932 may return inside the <Status Payload>. All status messages
1933 are defined in the section 5.3 SILC Command Status Types.
1936 Every command that has some kind of ID as argument (for example
1937 <Client ID>) are actually ID Payloads, defined in [SILC2] that includes
1938 the type of the ID, length of the ID and the actual ID data. This
1939 way variable length ID's can be sent as arguments.
1943 5.2 SILC Commands List
1945 This section lists all SILC commands, however, it is expected that a
1946 implementation and especially client implementation has many more
1947 commands that has only local affect. These commands are official
1948 SILC commands that has both client and server sides and cannot be
1949 characterized as local commands.
1951 List of all defined commands in SILC follows.
1956 None. This is reserved command and must not be sent.
1959 1 SILC_COMMAND_WHOIS
1962 Arguments: (1) [<nickname>[@<server>]] (2) [<count>]
1963 (3) [<Client ID>] (n) [...]
1965 Whois command is used to query various information about specific
1966 user. The user maybe requested by their nickname and server name.
1967 The query may find multiple matching users as there are no unique
1968 nicknames in the SILC. The <count> option maybe given to narrow
1969 down the number of accepted results. If this is not defined there
1970 are no limit of accepted results. The query may also be narrowed
1971 down by defining the server name of the nickname.
1973 It is also possible to search the user by Client ID. If <Client ID>
1974 is provided server must use it as the search value instead of
1975 the <nickname>. One of the arguments must be given. It is also
1976 possible to define multiple Client ID's to search multiple users
1977 sending only one WHOIS command. In this case the Client ID's are
1978 appended as normal arguments. The server replies in this case
1979 with only one reply message for all requested users.
1981 To prevent miss-use of this service wildcards in the nickname
1982 or in the servername are not permitted. It is not allowed
1983 to request all users on some server. The WHOIS requests must
1984 be based on specific nickname request.
1986 The WHOIS request must be always sent to the router by server
1987 so that all users are searched. However, the server still must
1988 search its locally connected clients. The router must send
1989 this command to the server who owns the requested client. That
1990 server must reply to the command. Server must not send whois
1991 replies to the client until it has received the reply from its
1994 Reply messages to the command:
1997 Arguments: (1) <Status Payload> (2) <Client ID>
1998 (3) <nickname>[@<server>] (4) <username@host>
1999 (5) <real name> (6) [<Channel Payload
2001 (7) [<user mode>] (8) [<idle time>]
2004 This command may reply with several command reply messages to
2005 form a list of results. In this case the status payload will
2006 include STATUS_LIST_START status in the first reply and
2007 STATUS_LIST_END in the last reply to indicate the end of the
2008 list. If there are only one reply the status is set to normal
2011 The command replies include the Client ID of the nickname,
2012 nickname and servername, username and hostname and users real
2013 name. Client should process these replies only after the last
2014 reply has been received with the STATUS_LIST_END status. If the
2015 <count> option were defined in the query there will be only
2016 <count> many replies from the server.
2018 The server may return the list of channel the client has joined.
2019 In this case the list is list of Channel Payloads. The Mode Mask
2020 in the Channel Payload (see [SILC2] and section 2.3.2.3 for the
2021 Channel Payload) is the client's mode on the channel. The list
2022 is encoded by adding the Channel Payloads one after the other.
2027 SILC_STATUS_LIST_START
2028 SILC_STATUS_LIST_END
2029 SILC_STATUS_ERR_NO_SUCH_NICK
2030 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2031 SILC_STATUS_ERR_WILDCARDS
2032 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2033 SILC_STATUS_ERR_TOO_MANY_PARAMS
2036 2 SILC_COMMAND_WHOWAS
2039 Arguments: (1) <nickname>[@<server>] (2) [<count>]
2041 Whowas. This command is used to query history information about
2042 specific user. The user maybe requested by their nickname and
2043 server name. The query may find multiple matching users as there
2044 are no unique nicknames in the SILC. The <count> option maybe
2045 given to narrow down the number of accepted results. If this
2046 is not defined there are no limit of accepted results. The query
2047 may also be narrowed down by defining the server name of the
2050 To prevent miss-use of this service wildcards in the nickname
2051 or in the servername are not permitted. The WHOWAS requests must
2052 be based on specific nickname request.
2054 The WHOWAS request must be always sent to the router by server
2055 so that all users are searched. However, the server still must
2056 search its locally connected clients.
2058 Reply messages to the command:
2061 Arguments: (1) <Status Payload> (2) <Client ID>
2062 (3) <nickname>[@<server>] (4) <username@host>
2065 This command may reply with several command reply messages to form
2066 a list of results. In this case the status payload will include
2067 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
2068 the last reply to indicate the end of the list. If there are only
2069 one reply the status is set to normal STATUS_OK.
2071 The command replies with nickname and username and hostname.
2072 Every server must keep history for some period of time of its
2073 locally connected clients.
2078 SILC_STATUS_LIST_START
2079 SILC_STATUS_LIST_END
2080 SILC_STATUS_ERR_NO_SUCH_NICK
2081 SILC_STATUS_ERR_WILDCARDS
2082 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2083 SILC_STATUS_ERR_TOO_MANY_PARAMS
2086 3 SILC_COMMAND_IDENTIFY
2089 Arguments: (1) [<nickname>[@<server>]] (2) [<count>]
2090 (3) [<Client ID>] (n) [...]
2092 Identify. Identify command is almost analogous to WHOIS command,
2093 except that it does not return as much information. Only relevant
2094 information such as Client ID is returned. This is usually used
2095 to get the Client ID of a client used in the communication with
2098 The query may find multiple matching users as there are no unique
2099 nicknames in the SILC. The <count> option maybe given to narrow
2100 down the number of accepted results. If this is not defined there
2101 are no limit of accepted results. The query may also be narrowed
2102 down by defining the server name of the nickname.
2104 It is also possible to search the user by Client ID. If <Client ID>
2105 is provided server must use it as the search value instead of
2106 the <nickname>. One of the arguments must be given. It is also
2107 possible to define multiple Client ID's to search multiple users
2108 sending only one IDENTIFY command. In this case the Client ID's are
2109 appended as normal arguments. The server replies in this case
2110 with only one reply message for all requested users.
2112 To prevent miss-use of this service wildcards in the nickname
2113 or in the servername are not permitted. It is not allowed
2114 to request all users on some server. The IDENTIFY requests must
2115 be based on specific nickname request.
2117 Implementations may not want to give interface access to this
2118 command as it is hardly a command that would be used by an end user.
2119 However, it must be implemented as it is used with private message
2122 The IDENTIFY must be always sent to the router by server so that
2123 all users are searched. However, server must still search its
2124 locally connected clients.
2126 Reply messages to the command:
2129 Arguments: (1) <Status Payload> (2) <Client ID>
2130 (3) [<nickname>[@<server>]] (4) [<username@host>]
2132 This command may reply with several command reply messages to form
2133 a list of results. In this case the status payload will include
2134 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
2135 the last reply to indicate the end of the list. If there are only
2136 one reply the status is set to normal STATUS_OK.
2138 The command replies with Client ID of the nickname and if more
2139 information is available it may reply with nickname and username
2140 and hostname. If the <count> option were defined in the query
2141 there will be only <count> many replies from the server.
2146 SILC_STATUS_LIST_START
2147 SILC_STATUS_LIST_END
2148 SILC_STATUS_ERR_NO_SUCH_NICK
2149 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2150 SILC_STATUS_ERR_WILDCARDS
2151 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2152 SILC_STATUS_ERR_TOO_MANY_PARAMS
2158 Arguments: (1) <nickname>
2160 Set/change nickname. This command is used to set nickname for
2161 user. There is no limit of the length of the nickname in SILC.
2162 Nickname must not include any spaces (` '), non-printable
2163 characters, commas (`,') and any wildcard characters. Note:
2164 nicknames in SILC are case-sensitive which must be taken into
2165 account when searching clients by nickname.
2167 When nickname is changed new Client ID is generated. Server must
2168 distribute SILC_NOTIFY_TYPE_NICK_CHANGE to local clients on the
2169 channels (if any) the client is joined on. Then it must send
2170 SILC_PACKET_REPLACE_ID to its primary route to replace the old
2171 Client ID with the new one.
2173 Reply messages to the command:
2176 Arguments: (1) <Status Payload> (2) <New ID Payload>
2178 This command is replied always with New ID Payload that is
2179 generated by the server every time user changes their nickname.
2180 Client receiving this payload must start using the received
2181 Client ID as its current valid Client ID. The New ID Payload
2182 is described in [SILC2].
2187 SILC_STATUS_ERR_WILDCARDS
2188 SILC_STATUS_ERR_NICKNAME_IN_USE
2189 SILC_STATUS_ERR_BAD_NICKNAME
2190 SILC_STATUS_ERR_NOT_REGISTERED
2191 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2192 SILC_STATUS_ERR_TOO_MANY_PARAMS
2198 Arguments: (1) [<Channel ID>]
2200 The list command is used to list channels and their topics on the
2201 current server. If the <Channel ID> parameter is used, only the
2202 status of that channel is displayed. Secret channels are not
2203 listed at all. Private channels are listed with status indicating
2204 that the channel is private. Router may reply with all channels
2207 Reply messages to the command:
2210 Arguments: (1) <Status Payload> (2) <Channel ID>
2211 (3) <channel> (4) [<topic>]
2214 This command may reply with several command reply messages to form
2215 a list of results. In this case the status payload will include
2216 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
2217 the last reply to indicate the end of the list. If there are only
2218 one reply the status is set to normal STATUS_OK.
2220 This command replies with Channel ID, name and the topic of the
2221 channel. If the channel is private channel the <topic> includes
2227 SILC_STATUS_LIST_START
2228 SILC_STATUS_LIST_END
2229 SILC_STATUS_ERR_WILDCARDS
2230 SILC_STATUS_ERR_NOT_REGISTERED
2231 SILC_STATUS_ERR_TOO_MANY_PARAMS
2232 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2233 SILC_STATUS_ERR_NO_CHANNEL_ID
2234 SILC_STATUS_ERR_NO_SUCH_SERVER
2237 6 SILC_COMMAND_TOPIC
2240 Arguments: (1) <Channel ID> (2) [<topic>]]
2242 This command is used to change or view the topic of a channel.
2243 The topic for channel <Channel ID> is returned if there is no
2244 <topic> given. If the <topic> parameter is present, the topic
2245 for that channel will be changed, if the channel modes permit
2248 After setting the topic the server must send the notify type
2249 SILC_NOTIFY_TYPE_TOPIC_SET to its primary router and then to
2250 the channel which topic was changed.
2252 Reply messages to the command:
2255 Arguments: (1) <Status Payload> (2) <Channel ID>
2258 The command may reply with the topic of the channel if it is
2264 SILC_STATUS_ERR_NOT_ON_CHANNEL
2265 SILC_STATUS_ERR_WILDCARDS
2266 SILC_STATUS_ERR_NOT_REGISTERED
2267 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2268 SILC_STATUS_ERR_NO_SUCH_CHANNEL
2269 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2270 SILC_STATUS_ERR_NO_CHANNEL_ID
2271 SILC_STATUS_ERR_BAD_CHANNEL_ID
2272 SILC_STATUS_ERR_TOO_MANY_PARAMS
2273 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2276 7 SILC_COMMAND_INVITE
2279 Arguments: (1) <Channel ID> (2) [<Client ID>]
2280 (3) [<adding client>] (4) [<removing client>]
2282 This command is used to invite other clients to join to the
2283 channel. The <Client ID> argument is the target client's ID that
2284 is being invited. The <Channel ID> is the Channel ID of the
2285 requested channel. The sender of this command must be on the
2286 channel. The server must also send the notify type
2287 SILC_NOTIFY_TYPE_INVITE to its primary router and then to the
2288 client indicated by the <Client ID>.
2290 The <adding client> and <removing client> can be used to add to
2291 and remove from the invite list. The format of the <adding client>
2292 and <removing client> is as follows:
2294 [<nickname>[@<server>]!][<username>]@[<hostname>]
2296 When adding to or removing from the invite list the server must
2297 send the notify type SILC_NOTIFY_TYPE_INVITE to its primary router
2298 and must not send it to the client which was added to the list.
2299 The client which executes this command must have at least channel
2300 operator privileges to be able to add to or remove from the invite
2301 list. The wildcards may be used with this command. If adding or
2302 removing from than one clients then the lists are an comma (`,')
2305 Note that the <Client ID> provided must be resolved into correct
2306 nickname and hostname and add to the invite list before sending
2309 When this command is given with only <Channel ID> argument then
2310 the command merely returns the invite list of the channel. This
2311 command must fail if the requested channel does not exist, the
2312 requested <Client ID> is already on the channel or if the channel
2313 is invite only channel and the caller of this command does not
2314 have at least channel operator privileges.
2316 Reply messages to the command:
2319 Arguments: (1) <Status Payload> (2) <Channel ID>
2322 This command replies with the invite list of the channel if it
2328 SILC_STATUS_ERR_NOT_REGISTERED
2329 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2330 SILC_STATUS_ERR_TOO_MANY_PARAMS
2331 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2332 SILC_STATUS_ERR_NO_CLIENT_ID
2333 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2334 SILC_STATUS_ERR_NO_CHANNEL_ID
2335 SILC_STATUS_ERR_NOT_ON_CHANNEL
2336 SILC_STATUS_ERR_USER_ON_CHANNEL
2337 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2343 Arguments: (1) [<quit message>]
2345 This command is used by client to end SILC session. The server
2346 must close the connection to a client which sends this command.
2347 if <quit message> is given it will be sent to other clients on
2348 channel if the client is on channel when quitting.
2350 Reply messages to the command:
2352 This command does not reply anything.
2358 Arguments: (1) <Client ID> (2) [<comment>]
2360 This command is used by SILC operators to remove a client from
2361 SILC network. The removing has temporary effects and client may
2362 reconnect to SILC network. The <Client ID> is the client to be
2363 removed from SILC. The <comment> argument may be provided to
2364 give to the removed client some information why it was removed
2367 When killing a client the router must first send notify type
2368 SILC_NOTIFY_TYPE_KILLED to all channels the client has joined.
2369 The packet must not be sent to the killed client on the channel.
2370 Then, the router must send the same notify type to its primary
2371 router. Finally, the router must send the same notify type to
2372 the client who was killed.
2374 Reply messages to the command:
2377 Arguments: (1) <Status Payload>
2379 This command replies only with Status Payload.
2384 SILC_STATUS_ERR_WILDCARDS
2385 SILC_STATUS_ERR_NOT_REGISTERED
2386 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2387 SILC_STATUS_ERR_TOO_MANY_PARAMS
2388 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2389 SILC_STATUS_ERR_NO_CLIENT_ID
2390 SILC_STATUS_ERR_NO_ROUTER_PRIV
2393 10 SILC_COMMAND_INFO
2396 Arguments: (1) [<server>] (2) [<Server ID>]
2398 This command is used to fetch various information about a server.
2399 If <server> argument is specified the command must be sent to
2400 the requested server.
2402 If the <Server ID> is specified the server information if fetched
2403 by the provided Server ID.
2405 Reply messages to the command:
2408 Arguments: (1) <Status Payload> (2) <Server ID>
2409 (3) <server name> (4) <string>
2411 This command replies with the Server ID of the server and a
2412 string which tells the information about the server.
2417 SILC_STATUS_ERR_WILDCARDS
2418 SILC_STATUS_ERR_NOT_REGISTERED
2419 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2420 SILC_STATUS_ERR_TOO_MANY_PARAMS
2421 SILC_STATUS_ERR_NO_SUCH_SERVER
2422 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2423 SILC_STATUS_ERR_NO_SERVER_ID
2426 11 SILC_COMMAND_CONNECT
2429 Arguments: (1) <remote server/router> (2) [<port>]
2431 This command is used by operators to force a server to try to
2432 establish a new connection to remote server or router. The
2433 Operator must specify the server/router to be connected by
2434 setting <remote server> argument. The port is 32 bit MSB value.
2436 Reply messages to the command:
2439 Arguments: (1) <Status Payload>
2441 This command replies only with Status Payload.
2448 SILC_STATUS_ERR_WILDCARDS
2449 SILC_STATUS_ERR_NOT_REGISTERED
2450 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2451 SILC_STATUS_ERR_TOO_MANY_PARAMS
2452 SILC_STATUS_ERR_NO_SERVER_PRIV
2453 SILC_STATUS_ERR_NO_ROUTER_PRIV
2456 12 SILC_COMMAND_PING
2459 Arguments: (1) <Server ID>
2461 This command is used by client and server to test the communication
2462 channel to its server if one suspects that the communication is not
2463 working correctly. The <Server ID> is the ID of the server the
2464 sender is connected to.
2466 Reply messages to the command:
2469 Arguments: (1) <Status Payload>
2471 This command replies only with Status Payload. Server returns
2472 SILC_STATUS_OK in Status Payload if pinging was successful.
2479 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2480 SILC_STATUS_ERR_TOO_MANY_PARAMS
2481 SILC_STATUS_ERR_NO_SERVER_ID
2482 SILC_STATUS_ERR_NO_SUCH_SERVER
2483 SILC_STATUS_ERR_NOT_REGISTERED
2486 13 SILC_COMMAND_OPER
2489 Arguments: (1) <username> (2) <authentication payload>
2491 This command is used by normal client to obtain server operator
2492 privileges on some server or router. Note that router operator
2493 has router privileges that supersedes the server operator
2494 privileges and this does not obtain those privileges. Client
2495 must use SILCOPER command to obtain router level privileges.
2497 The <username> is the username set in the server configurations
2498 as operator. The <authentication payload> is the data that the
2499 client is authenticated against. It may be passphrase prompted
2500 for user on client's screen or it may be public key or certificate
2501 authentication data (data signed with private key).
2503 After changing the mode server must send the notify type
2504 SILC_NOTIFY_TYPE_UMODE_CHANGE to its primary router.
2506 Reply messages to the command:
2509 Arguments: (1) <Status Payload>
2511 This command replies only with Status Payload.
2516 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2517 SILC_STATUS_ERR_TOO_MANY_PARAMS
2518 SILC_STATUS_ERR_NOT_REGISTERED
2519 SILC_STATUS_ERR_AUTH_FAILED
2522 14 SILC_COMMAND_JOIN
2525 Arguments: (1) <channel> (2) <Client ID>
2526 (3) [<passphrase>] (4) [<cipher>]
2529 Join to channel/create new channel. This command is used to
2530 join to a channel. If the channel does not exist the channel is
2531 created. If server is normal server this command must be sent
2532 to router who will create the channel. The channel may be
2533 protected with passphrase. If this is the case the passphrase
2534 must be sent along the join command.
2536 The name of the <channel> must not include any spaces (` '),
2537 non-printable characters, commas (`,') or any wildcard characters.
2539 The second argument <Client ID> is the Client ID of the client who
2540 is joining to the client. When client sends this command to the
2541 server the <Client ID> must be the client's own ID.
2543 Cipher to be used to secure the traffic on the channel may be
2544 requested by sending the name of the requested <cipher>. This
2545 is used only if the channel does not exist and is created. If
2546 the channel already exists the cipher set previously for the
2547 channel will be used to secure the traffic. The computed MACs
2548 of the channel message are produced by the default HMAC or by
2549 the <hmac> provided for the command.
2551 The server must check whether the user is allowed to join to
2552 the requested channel. Various modes set to the channel affect
2553 the ability of the user to join the channel. These conditions
2556 o The user must be invited to the channel if the channel
2557 is invite-only channel.
2559 o The Client ID/nickname/username/hostname must not match
2562 o The correct passphrase must be provided if passphrase
2563 is set to the channel.
2565 o The user count limit, if set, must not be reached.
2567 Reply messages to the command:
2570 Arguments: (1) <Status Payload> (2) <channel>
2571 (3) <Channel ID> (4) <Client ID>
2572 (5) <channel mode mask> (6) <created>
2573 (7) [<Channel Key Payload>] (8) [<ban list>]
2574 (9) [<invite list>] (10) [<topic>]
2575 (11) [<hmac>] (12) <list count>
2576 (13) <Client ID list> (14) <client mode list>
2578 This command replies with the channel name requested by the
2579 client, channel ID of the channel and topic of the channel
2580 if it exists. The <Client ID> is the Client ID which was joined
2581 to the channel. It also replies with the channel mode mask
2582 which tells all the modes set on the channel. If the
2583 channel is created the mode mask is zero (0). If ban mask
2584 and/or invite list is set they are sent as well.
2586 The <list count>, <Client ID list> and <client mode list> are
2587 the clients currently on the channel and their modes on the
2588 channel. The <Client ID list> is formed by adding the ID Payloads
2589 one after the other. The <client mode list> is formed by adding
2590 32 bit MSB first order values one after the other.
2592 Client receives the channel key in the reply message as well
2593 inside <Channel Key Payload>.
2598 SILC_STATUS_ERR_WILDCARDS
2599 SILC_STATUS_ERR_NOT_REGISTERED
2600 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2601 SILC_STATUS_ERR_TOO_MANY_PARAMS
2602 SILC_STATUS_ERR_BAD_PASSWORD
2603 SILC_STATUS_ERR_CHANNEL_IS_FULL
2604 SILC_STATUS_ERR_NOT_INVITED
2605 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
2606 SILC_STATUS_ERR_BAD_CHANNEL
2607 SILC_STATUS_ERR_USER_ON_CHANNEL
2610 15 SILC_COMMAND_MOTD
2613 Arguments: (1) <server>
2615 This command is used to query the Message of the Day of the server.
2617 Reply messages to the command:
2620 Arguments: (1) <Status Payload> (2) <Server ID>
2623 This command replies with the motd message if it exists.
2628 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2629 SILC_STATUS_ERR_TOO_MANY_PARAMS
2630 SILC_STATUS_ERR_NOT_REGISTERED
2631 SILC_STATUS_ERR_NO_SUCH_SERVER
2634 16 SILC_COMMAND_UMODE
2637 Arguments: (1) <Client ID> (2) <client mode mask>
2639 This command is used by client to set/unset modes for itself.
2640 However, there are some modes that the client may not set itself,
2641 but they will be set by server. However, client may unset any
2642 mode. Modes may be masked together ORing them thus having
2643 several modes set. Client must keep its client mode mask
2644 locally so that the mode setting/unsetting would work without
2645 problems. Client may change only its own modes.
2647 After changing the mode server must send the notify type
2648 SILC_NOTIFY_TYPE_UMODE_CHANGE to its primary router.
2650 The following client modes are defined:
2652 0x0000 SILC_UMODE_NONE
2654 No specific mode for client. This is the initial
2655 setting when new client is created. The client is
2659 0x0001 SILC_UMODE_SERVER_OPERATOR
2661 Marks the user as server operator. Client cannot
2662 set this mode itself. Server sets this mode to the
2663 client when client attains the server operator
2664 privileges by SILC_COMMAND_OPER command. Client
2665 may unset the mode itself.
2668 0x0002 SILC_UMODE_ROUTER_OPERATOR
2670 Marks the user as router (SILC) operator. Client
2671 cannot this mode itself. Router sets this mode to
2672 the client when client attains the router operator
2673 privileges by SILC_COMMAND_SILCOPER command. Client
2674 may unset the mode itself.
2676 0x0004 SILC_UMODE_GONE
2678 Marks that the user is not currently present in the
2679 SILC Network. Client may set and unset this mode.
2681 Reply messages to the command:
2684 Arguments: (1) <Status Payload> (2) <client mode mask>
2686 This command replies with the changed client mode mask that
2687 the client is required to keep locally.
2693 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2694 SILC_STATUS_ERR_TOO_MANY_PARAMS
2695 SILC_STATUS_ERR_NOT_REGISTERED
2696 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2697 SILC_STATUS_ERR_BAD_CLIENT_ID
2698 SILC_STATUS_ERR_NOT_YOU
2699 SILC_STATUS_ERR_PERM_DENIED
2700 SILC_STATUS_ERR_UNKNOWN_MODE
2701 SILC_STATUS_ERR_NO_CLIENT_ID
2704 17 SILC_COMMAND_CMODE
2707 Arguments: (1) <Channel ID> (2) <channel mode mask>
2708 (3) [<user limit>] (4) [<passphrase>]
2709 (5) [<cipher>] (6) [<hmac>]
2710 (7) [<auth payload>]
2712 This command is used by client to set or change channel flags on
2713 a channel. Channel has several modes that set various properties
2714 of a channel. Modes may be masked together by ORing them thus
2715 having several modes set. The <Channel ID> is the ID of the
2716 target channel. The client changing channel mode must be on
2717 the same channel and poses sufficient privileges to be able to
2720 When the mode is changed SILC_NOTIFY_TYPE_CMODE_CHANGE notify
2721 type is distributed to the channel.
2723 The following channel modes are defined:
2725 0x0000 SILC_CMODE_NONE
2727 No specific mode on channel. This is the default when
2728 channel is created. This means that channel is just plain
2732 0x0001 SILC_CMODE_PRIVATE
2734 Channel is private channel. Private channels are shown
2735 in the channel list listed with SILC_COMMAND_LIST command
2736 with indication that the channel is private. Also,
2737 client on private channel will no be detected to be on
2738 the channel as the channel is not shown in the client's
2739 currently joined channel list. Channel founder and
2740 channel operator may set/unset this mode.
2742 Typical implementation would use [+|-]p on user interface
2743 to set/unset this mode.
2746 0x0002 SILC_CMODE_SECRET
2748 Channel is secret channel. Secret channels are not shown
2749 in the list listed with SILC_COMMAND_LIST command. Secret
2750 channels can be considered to be invisible channels.
2751 Channel founder and channel operator may set/unset this
2754 Typical implementation would use [+|-]s on user interface
2755 to set/unset this mode.
2758 0x0004 SILC_CMODE_PRIVKEY
2760 Channel uses private channel key to protect the traffic
2761 on the channel. When this mode is set the client will be
2762 responsible to set the key it wants to use to encrypt and
2763 decrypt the traffic on channel. Server generated channel
2764 keys are not used at all. This mode provides additional
2765 security as clients on channel may agree to use private
2766 channel key that even servers do not know. Naturally,
2767 this requires that every client on the channel knows
2768 the key before hand (it is considered to be pre-shared-
2769 key). This specification does not define how the private
2770 channel key is set as it is entirely local setting on
2773 As it is local setting it is possible to have several
2774 private channel keys on one channel. In this case several
2775 clients can talk on same channel but only those clients
2776 that share the key with the message sender will be able
2777 to hear the talking. Client should not display those
2778 message for the end user that it is not able to decrypt
2779 when this mode is set.
2781 Only channel founder may set/unset this mode. If this
2782 mode is unset the server will distribute new channel
2783 key to all clients on the channel which will be used
2786 Typical implementation would use [+|-]k on user interface
2787 to set/unset this mode.
2790 0x0008 SILC_CMODE_INVITE
2792 Channel is invite only channel. Client may join to this
2793 channel only if it is invited to the channel. Channel
2794 founder and channel operator may set/unset this mode.
2796 Typical implementation would use [+|-]i on user interface
2797 to set/unset this mode.
2800 0x0010 SILC_CMODE_TOPIC
2802 The topic of the channel may only be set by client that
2803 is channel founder or channel operator. Normal clients
2804 on channel will not be able to set topic when this mode
2805 is set. Channel founder and channel operator may set/
2808 Typical implementation would use [+|-]t on user interface
2809 to set/unset this mode.
2812 0x0020 SILC_CMODE_ULIMIT
2814 User limit has been set to the channel. New clients
2815 may not join to the channel when the limit set is
2816 reached. Channel founder and channel operator may set/
2817 unset the limit. The <user limit> argument is the
2818 number of limited users.
2820 Typical implementation would use [+|-]l on user interface
2821 to set/unset this mode.
2824 0x0040 SILC_CMODE_PASSPHRASE
2826 Passphrase has been set to the channel. Client may
2827 join to the channel only if it is able to provide the
2828 correct passphrase. Setting passphrases to channel
2829 is entirely safe as all commands are protected in the
2830 SILC network. Only channel founder may set/unset
2831 the passphrase. The <passphrase> argument is the
2834 Typical implementation would use [+|-]a on user interface
2835 to set/unset this mode.
2838 0x0080 SILC_CMODE_CIPHER
2840 Sets specific cipher to be used to protect channel
2841 traffic. The <cipher> argument is the requested cipher.
2842 When set or unset the server must re-generate new
2843 channel key. Only channel founder may set the cipher of
2844 the channel. When unset the new key is generated using
2845 default cipher for the channel.
2847 Typical implementation would use [+|-]c on user interface
2848 to set/unset this mode.
2851 0x0100 SILC_CMODE_HMAC
2853 Sets specific hmac to be used to compute the MACs of the
2854 channel message. The <hmac> argument is the requested hmac.
2855 Only channel founder may set the hmac of the channel.
2857 Typical implementation would use [+|-]h on user interface
2858 to set/unset this mode.
2861 0x0200 SILC_CMODE_FOUNDER_AUTH
2863 Channel founder can set this mode to be able to regain
2864 channel founder rights even if the client leaves the
2865 channel. The <auth payload> is the Authentication Payload
2866 consisting of the authentication method and authentication
2867 data to be used in the authentication. The server must
2868 not accept NONE authentication method. Also, if the
2869 method is public key authentication the server must not
2870 save the authentication data from the payload as the
2871 data is different on all authentications. In this case the
2872 server only saves the authentication method.
2874 Note, that this mode is effective only in the current server.
2875 The client must connect to the same server later to be able
2876 to regain the channel founder rights. The server must save
2877 the public key of the channel founder and use that to identify
2878 the client who is claiming the channel founder rights.
2879 The rights may be claimed by the SILC_CUMODE_FOUNDER
2880 channel user mode using SILC_COMMAND_CUMODE command. The
2881 set authentication data remains valid as long as the channel
2882 exists or until the founder unsets this mode.
2884 Typical implementation would use [+|-]f on user interface
2885 to set/unset this mode.
2888 To make the mode system work, client must keep the channel mode
2889 mask locally so that the mode setting and unsetting would work
2890 without problems. The client receives the initial channel mode
2891 mask when it joins to the channel. When the mode changes on
2892 channel the servers distributes the changed channel mode mask to
2893 all clients on the channel by sending SILC_NOTIFY_TYPE_CMODE_CHANGE
2896 Reply messages to the command:
2899 Arguments: (1) <Status Payload> (2) <channel mode mask>
2901 This command replies with the changed channel mode mask that
2902 client is required to keep locally.
2907 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2908 SILC_STATUS_ERR_TOO_MANY_PARAMS
2909 SILC_STATUS_ERR_NOT_REGISTERED
2910 SILC_STATUS_ERR_NOT_ON_CHANNEL
2911 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2912 SILC_STATUS_ERR_BAD_CHANNEL_ID
2913 SILC_STATUS_ERR_NO_CHANNEL_ID
2914 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2915 SILC_STATUS_ERR_UNKNOWN_MODE
2916 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2919 18 SILC_COMMAND_CUMODE
2922 Arguments: (1) <Channel ID> (2) <mode mask>
2923 (3) <Client ID> (4) [<auth payload>]
2925 This command is used by client to change channel user modes on
2926 channel. Users on channel may have some special modes and this
2927 command is used by channel operators to set or change these modes.
2928 The <Channel ID> is the ID of the target channel. The <mode mask>
2929 is OR'ed mask of modes. The <Client ID> is the target client.
2930 The client changing channel user modes must be on the same channel
2931 as the target client and poses sufficient privileges to be able to
2934 When the mode is changed SILC_NOTIFY_TYPE_CUMODE_CHANGE notify
2935 type is distributed to the channel.
2937 The following channel modes are defined:
2939 0x0000 SILC_CUMODE_NONE
2941 No specific mode. This is the normal situation for client.
2942 Also, this is the mode set when removing all modes from client.
2945 0x0001 SILC_CUMODE_FOUNDER
2947 The client is channel founder of the channel. Usually this
2948 mode is set only by the server when the channel was created.
2949 However, if the SILC_CMODE_FOUNDER_AUTH channel mode has
2950 been set, the client can claim channel founder privileges
2951 by providing the <auth payload> that the server will use
2952 to authenticate the client. The client can remove this
2956 0x0002 SILC_CUMODE_OPERATOR
2958 Sets channel operator privileges on the channel for a
2959 client on the channel. Channel founder and channel operator
2960 may set/unset (promote/demote) this mode.
2962 Reply messages to the command:
2965 Arguments: (1) <Status Payload> (2) <channel user mode mask>
2968 This command replies with the changed channel user mode mask that
2969 client is required to keep locally. The <Client ID> is the target
2975 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2976 SILC_STATUS_ERR_TOO_MANY_PARAMS
2977 SILC_STATUS_ERR_NOT_REGISTERED
2978 SILC_STATUS_ERR_NOT_ON_CHANNEL
2979 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2980 SILC_STATUS_ERR_BAD_CHANNEL_ID
2981 SILC_STATUS_ERR_NO_CHANNEL_ID
2982 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2983 SILC_STATUS_ERR_UNKNOWN_MODE
2984 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2985 SILC_STATUS_ERR_AUTH_FAILED
2988 19 SILC_COMMAND_KICK
2991 Arguments: (1) <Channel ID> (2) <Client ID>
2994 This command is used by channel operators to remove a client from
2995 channel. The <channel> argument is the channel the client to be
2996 removed is on currently. Note that the "kicker" must be on the same
2997 channel. If <comment> is provided it will be sent to the removed
3000 After kicking the client the server must send the notify type
3001 SILC_NOTIFY_TYPE_KICKED to the channel and to its primary router.
3002 The channel key must also be re-generated after kicking.
3004 Reply messages to the command:
3007 Arguments: (1) <Status Payload>
3009 This command replies only with Status Payload.
3014 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
3015 SILC_STATUS_ERR_TOO_MANY_PARAMS
3016 SILC_STATUS_ERR_NOT_REGISTERED
3017 SILC_STATUS_ERR_NO_SUCH_CHANNEL
3018 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
3019 SILC_STATUS_ERR_NO_CHANNEL_PRIV
3020 SILC_STATUS_ERR_NO_CLIENT_ID
3026 Arguments: (1) <Channel ID> (2) [<adding client>]
3027 (3) [<removing client>]
3029 This command is used to manage the ban list of the channel
3030 indicated by the <Channel ID>. A client that is banned from
3031 channel is no longer able to join the channel. The client which
3032 is executing this command must have at least channel operator
3033 privileges on the channel.
3035 The <adding client> and <removing client> are used to add to and
3036 remove from the ban list. The format of the <adding client> and
3037 the <removing client> is of following format:
3039 [<nickname>[@<server>]!][<username>]@[<hostname>]
3041 The server must send the notify type SILC_NOTIFY_TYPE_BAN to its
3042 primary router after adding to or removing from the ban list.
3043 The wildcards may be used with this command. If adding or removing
3044 from than one clients then the lists are an comma (`,') separated
3047 If this command is executed without the ban arguments the command
3048 merely replies with the current ban list.
3051 Reply messages to the command:
3054 Arguments: (1) <Status Payload> (2) <Channel ID>
3057 This command replies with the <Channel ID> of the channel and
3058 the current <ban list> of the channel if it exists.
3063 SILC_STATUS_ERR_NOT_REGISTERED
3064 SILC_STATUS_ERR_TOO_MANY_PARAMS
3065 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
3066 SILC_STATUS_ERR_NO_CHANNEL_ID
3067 SILC_STATUS_ERR_NOT_ON_CHANNEL
3068 SILC_STATUS_ERR_NO_CHANNEL_PRIV
3071 21 SILC_COMMAND_CLOSE
3074 Arguments: (1) <remote server/router> (2) [<port>]
3076 This command is used only by operator to close connection to a
3079 Reply messages to the command:
3082 Arguments: (1) <Status Payload>
3084 This command replies only with Status Payload.
3089 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
3090 SILC_STATUS_ERR_TOO_MANY_PARAMS
3091 SILC_STATUS_ERR_NOT_REGISTERED
3092 SILC_STATUS_ERR_NO_SUCH_SERVER
3093 SILC_STATUS_ERR_NO_SERVER_PRIV
3094 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
3097 22 SILC_COMMAND_SHUTDOWN
3102 This command is used only by operator to shutdown the server.
3103 All connections to the server will be closed and the server is
3106 Reply messages to the command:
3111 Arguments: (1) <Status Payload>
3113 This command replies only with Status Payload.
3118 SILC_STATUS_ERR_NOT_REGISTERED
3119 SILC_STATUS_ERR_NO_SERVER_PRIV
3122 23 SILC_COMMAND_SILCOPER
3125 Arguments: (1) <username> (2) <authentication payload>
3127 This command is used by normal client to obtain router operator
3128 privileges (also known as SILC operator) on some router. Note
3129 that router operator has router privileges that supersedes the
3130 server operator privileges.
3132 The <username> is the username set in the server configurations
3133 as operator. The <authentication payload> is the data that the
3134 client is authenticated against. It may be passphrase prompted
3135 for user on client's screen or it may be public key
3136 authentication data (data signed with private key), or
3139 Difference between router operator and server operator is that
3140 router operator is able to handle cell level properties while
3141 server operator (even on router server) is able to handle only
3142 local properties, such as, local connections and normal server
3145 After changing the mode server must send the notify type
3146 SILC_NOTIFY_TYPE_UMODE_CHANGE to its primary router.
3148 Reply messages to the command:
3151 Arguments: (1) <Status Payload>
3153 This command replies only with Status Payload.
3158 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
3159 SILC_STATUS_ERR_TOO_MANY_PARAMS
3160 SILC_STATUS_ERR_NOT_REGISTERED
3161 SILC_STATUS_ERR_AUTH_FAILED
3164 24 SILC_COMMAND_LEAVE
3167 Arguments: (1) <Channel ID>
3169 This command is used by client to leave a channel the client is
3172 When leaving the channel the server must send the notify type
3173 SILC_NOTIFY_TYPE_LEAVE to its primary router and to the channel.
3174 The channel key must also be re-generated when leaving the channel
3175 and distribute it to all clients still currently on the channel.
3177 Reply messages to the command:
3180 Arguments: (1) <Status Payload>
3182 This command replies only with Status Payload.
3187 SILC_STATUS_ERR_NOT_REGISTERED
3188 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
3189 SILC_STATUS_ERR_TOO_MANY_PARAMS
3190 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
3191 SILC_STATUS_ERR_BAD_CHANNEL_ID
3192 SILC_STATUS_ERR_NO_CHANNEL_ID
3195 25 SILC_COMMAND_USERS
3198 Arguments: (1) <Channel ID>
3200 This command is used to list user names currently on the requested
3201 channel; argument <Channel ID>. The server must resolve the
3202 user names and send a comma (`,') separated list of user names
3203 on the channel. Server or router may resolve the names by sending
3204 SILC_COMMAND_WHOIS commands.
3206 If the requested channel is a private or secret channel, this
3207 command must not send the list of users, as private and secret
3208 channels cannot be seen by outside. In this case the returned
3209 name list may include a indication that the server could not
3210 resolve the names of the users on the channel. Also, in this case
3211 Client ID's or client modes are not sent either.
3213 Reply messages to the command:
3216 Arguments: (1) <Status Payload> (2) <Channel ID>
3217 (3) <list count> (4) <Client ID list>
3218 (5) <client mode list>
3220 This command replies with the Channel ID of the requested channel
3221 Client ID list of the users on the channel and list of their modes.
3222 The Client ID list has Client ID's of all users in the list. The
3223 <Client ID list> is formed by adding Client ID's one after another.
3224 The <client mode list> is formed by adding client's user modes on
3225 the channel one after another (4 bytes (32 bits) each). The <list
3226 count> of length of 4 bytes (32 bits), tells the number of entries
3227 in the lists. Both lists must have equal number of entries.
3232 SILC_STATUS_ERR_NOT_REGISTERED
3233 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
3234 SILC_STATUS_ERR_TOO_MANY_PARAMS
3235 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
3236 SILC_STATUS_ERR_BAD_CHANNEL_ID
3237 SILC_STATUS_ERR_NO_CHANNEL_ID
3238 SILC_STATUS_ERR_NOT_ON_CHANNEL
3241 26 SILC_COMMAND_GETKEY
3244 Arguments: (1) <ID Payload>
3246 This command is used to fetch the public key of the client or
3247 server indicated by the <ID Payload>. The public key is fetched
3248 from the server where to the client is connected.
3250 Reply messages to the command:
3253 Arguments: (1) <Status Payload> (2) <ID Payload>
3254 (3) <Public Key Payload>
3256 This command replies with the client's or server's ID and with
3257 the <Public Key Payload>.
3262 SILC_STATUS_ERR_NOT_REGISTERED
3263 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
3264 SILC_STATUS_ERR_TOO_MANY_PARAMS
3265 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
3266 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
3271 Currently undefined commands.
3276 These commands are reserved for private use and will not be defined
3280 255 SILC_COMMAND_MAX
3282 Reserved command. This must not be sent.
3287 5.3 SILC Command Status Types
3290 5.3.1 SILC Command Status Payload
3292 Command Status Payload is sent in command reply messages to indicate
3293 the status of the command. The payload is one of argument in the
3294 command thus this is the data area in Command Argument Payload described
3295 in [SILC2]. The payload is only 2 bytes of length. The following diagram
3296 represents the Command Status Payload (field is always in MSB order).
3305 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
3306 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3308 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3312 Figure 6: SILC Command Status Payload
3316 o Status Message (2 bytes) - Indicates the status message.
3317 All Status messages are described in the next section.
3322 5.3.2 SILC Command Status List
3324 Command Status messages are returned in the command reply messages
3325 to indicate whether the command were executed without errors. If error
3326 has occured the status tells which error occured. Status payload only
3327 sends numeric reply about the status. Receiver of the payload must
3328 convert the numeric values into human readable error messages. The
3329 list of status messages below has an example human readable error
3330 messages that client may display for the user.
3332 List of all defined command status messages following.
3335 Generic status messages:
3339 Ok status. Everything went Ok. The status payload maybe
3340 safely ignored in this case.
3342 1 SILC_STATUS_LIST_START
3344 Start of the list. There will be several command replies and
3345 this reply is the start of the list.
3347 2 SILC_STATUS_LIST_ITEM
3349 Item in the list. This is one of the item in the list but not the
3352 3 SILC_STATUS_LIST_END
3354 End of the list. There were several command replies and this
3355 reply is the last of the list. There won't be other replies
3356 belonging to this list after this one.
3360 Currently undefined and has been reserved for the future.
3363 Error status message:
3365 10 SILC_STATUS_ERR_NO_SUCH_NICK
3367 "No such nickname". Requested nickname does not exist.
3369 11 SILC_STATUS_ERR_NO_SUCH_CHANNEL
3371 "No such channel". Requested channel name does not exist.
3373 12 SILC_STATUS_ERR_NO_SUCH_SERVER
3375 "No such server". Requested server name does not exist.
3377 13 SILC_STATUS_ERR_TOO_MANY_TARGETS
3379 "Duplicate recipients. No message delivered". Message were
3380 tried to be sent to recipient which has several occurrences in
3383 14 SILC_STATUS_ERR_NO_RECIPIENT
3385 "No recipient given". Command required recipient which was
3388 15 SILC_STATUS_ERR_UNKNOWN_COMMAND
3390 "Unknown command". Command sent to server is unknown by the
3393 16 SILC_STATUS_ERR_WILDCARDS
3395 "Wildcards cannot be used". Wildcards were provided but they
3398 17 SILC_STATUS_ERR_NO_CLIENT_ID
3400 "No Client ID given". Client ID were expected as command
3401 parameter but were not found.
3403 18 SILC_STATUS_ERR_NO_CHANNEL_ID
3405 "No Channel ID given". Channel ID were expected as command
3406 parameter but were not found.
3408 19 SILC_STATUS_ERR_NO_SERVER_ID
3410 "No Serve ID given". Server ID were expected as command
3411 parameter but were not found.
3413 20 SILC_STATUS_ERR_BAD_CLIENT_ID
3415 "Bad Client ID". Client ID provided were erroneous.
3417 21 SILC_STATUS_ERR_BAD_CHANNEL_ID
3419 "Bad Channel ID". Channel ID provided were erroneous.
3421 22 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
3423 "No such Client ID". Client ID provided does not exist.
3425 23 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
3427 "No such Channel ID". Channel ID provided does not exist.
3429 24 SILC_STATUS_ERR_NICKNAME_IN_USE
3431 "Nickname already exists". Nickname created could not be
3432 registered because number of same nicknames were already set to
3433 maximum. This is not expected to happen in real life but is
3436 25 SILC_STATUS_ERR_NOT_ON_CHANNEL
3438 "You are not on that channel". The command were specified for
3439 channel user is not currently on.
3441 26 SILC_STATUS_ERR_USER_NOT_ON_CHANNEL
3443 "They are not on channel". The requested target client is not
3444 on requested channel.
3446 27 SILC_STATUS_ERR_USER_ON_CHANNEL
3448 "User already on channel". User were invited on channel they
3451 28 SILC_STATUS_ERR_NOT_REGISTERED
3453 "You have not registered". User executed command that requires
3454 the client to be registered on the server before it may be
3457 29 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
3459 "Not enough parameters". Command requires more parameters
3462 30 SILC_STATUS_ERR_TOO_MANY_PARAMS
3464 "Too many parameters". Too many parameters were provided
3467 31 SILC_STATUS_ERR_PERM_DENIED
3469 "Permission denied". Generic permission denied error status
3470 to indicate disallowed access.
3472 32 SILC_STATUS_ERR_BANNED_FROM_SERVER
3474 "You are banned from this server". The client tried to register
3475 on server that has explicitly denied this host to connect.
3477 33 SILC_STATUS_ERR_BAD_PASSWORD
3479 "Cannot join channel. Incorrect password". Password provided for
3480 channel were not accepted.
3482 34 SILC_STATUS_ERR_CHANNEL_IS_FULL
3484 "Cannot join channel. Channel is full". The channel is full
3485 and client cannot be joined to it.
3487 35 SILC_STATUS_ERR_NOT_INVITED
3489 "Cannot join channel. You have not been invited". The channel
3490 is invite only channel and client has not been invited.
3492 36 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
3494 "Cannot join channel. You have been banned". The client has
3495 been banned from the channel.
3497 37 SILC_STATUS_ERR_UNKNOWN_MODE
3499 "Unknown mode". Mode provided by the client were unknown to
3502 38 SILC_STATUS_ERR_NOT_YOU
3504 "Cannot change mode for other users". User tried to change
3505 someone else's mode.
3507 39 SILC_STATUS_ERR_NO_CHANNEL_PRIV
3509 "Permission denied. You are not channel operator". Command may
3510 be executed only by channel operator.
3512 40 SILC_STATUS_ERR_NO_CHANNEL_FOPRIV
3514 "Permission denied. You are not channel founder". Command may
3515 be executed only by channel operator.
3517 41 SILC_STATUS_ERR_NO_SERVER_PRIV
3519 "Permission denied. You are not server operator". Command may
3520 be executed only by server operator.
3522 42 SILC_STATUS_ERR_NO_ROUTER_PRIV
3524 "Permission denied. You are not SILC operator". Command may be
3525 executed only by router (SILC) operator.
3527 43 SILC_STATUS_ERR_BAD_NICKNAME
3529 "Bad nickname". Nickname requested contained illegal characters
3532 44 SILC_STATUS_ERR_BAD_CHANNEL
3534 "Bad channel name". Channel requested contained illegal characters
3537 45 SILC_STATUS_ERR_AUTH_FAILED
3539 "Authentication failed". The authentication data sent as
3540 argument were wrong and thus authentication failed.
3542 46 SILC_STATUS_ERR_UNKOWN_ALGORITHM
3544 "The algorithm was not supported." The server does not support the
3545 requested algorithm.
3547 47 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
3549 "No such Server ID". Server ID provided does not exist.
3555 6 Security Considerations
3557 Security is central to the design of this protocol, and these security
3558 considerations permeate the specification. Common security considerations
3559 such as keeping private keys truly private and using adequate lengths for
3560 symmetric and asymmetric keys must be followed in order to maintain the
3561 security of this protocol.
3567 [SILC2] Riikonen, P., "SILC Packet Protocol", Internet Draft,
3570 [SILC3] Riikonen, P., "SILC Key Exchange and Authentication
3571 Protocols", Internet Draft, June 2000.
3573 [IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
3576 [IRC-ARCH] Kalt, C., "Internet Relay Chat: Architecture", RFC 2810,
3579 [IRC-CHAN] Kalt, C., "Internet Relay Chat: Channel Management", RFC
3582 [IRC-CLIENT] Kalt, C., "Internet Relay Chat: Client Protocol", RFC
3585 [IRC-SERVER] Kalt, C., "Internet Relay Chat: Server Protocol", RFC
3588 [SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
3591 [PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
3594 [SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
3597 [PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
3598 Infrastructure, Certificate and CRL Profile", RFC 2459,
3601 [Schneier] Schneier, B., "Applied Cryptography Second Edition",
3602 John Wiley & Sons, New York, NY, 1996.
3604 [Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
3607 [OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
3608 RFC 2412, November 1998.
3610 [ISAKMP] Maughan D., et al, "Internet Security Association and
3611 Key Management Protocol (ISAKMP)", RFC 2408, November
3614 [IKE] Harkins D., and Carrel D., "The Internet Key Exchange
3615 (IKE)", RFC 2409, November 1998.
3617 [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
3618 Authentication", RFC 2104, February 1997.
3620 [PKCS1] Kalinski, B., and Staddon, J., "PKCS #1 RSA Cryptography
3621 Specifications, Version 2.0", RFC 2437, October 1998.
3633 EMail: priikone@poseidon.pspt.fi
3635 This Internet-Draft expires 6 Jun 2001