8 .ds RF FORMFEED[Page %]
17 Network Working Group P. Riikonen
19 draft-riikonen-silc-pp-07.txt 28 July 2003
20 Expires: 28 January 2004
26 <draft-riikonen-silc-pp-07.txt>
31 This document is an Internet-Draft and is in full conformance with
32 all provisions of Section 10 of RFC 2026. Internet-Drafts are
33 working documents of the Internet Engineering Task Force (IETF), its
34 areas, and its working groups. Note that other groups may also
35 distribute working documents as Internet-Drafts.
37 Internet-Drafts are draft documents valid for a maximum of six months
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39 time. It is inappropriate to use Internet-Drafts as reference
40 material or to cite them other than as "work in progress."
42 The list of current Internet-Drafts can be accessed at
43 http://www.ietf.org/ietf/1id-abstracts.txt
45 The list of Internet-Draft Shadow Directories can be accessed at
46 http://www.ietf.org/shadow.html
48 The distribution of this memo is unlimited.
54 This memo describes a Packet Protocol used in the Secure Internet Live
55 Conferencing (SILC) protocol, specified in the Secure Internet Live
56 Conferencing, Protocol Specification [SILC1]. This protocol describes
57 the packet types and packet payloads which defines the contents of the
58 packets. The protocol provides secure binary packet protocol that
59 assures that the contents of the packets are secured and authenticated.
73 1 Introduction .................................................. 3
74 1.1 Requirements Terminology .................................. 4
75 2 SILC Packet Protocol .......................................... 4
76 2.1 SILC Packet ............................................... 4
77 2.2 SILC Packet Header ........................................ 5
78 2.3 SILC Packet Types ......................................... 7
79 2.3.1 SILC Packet Payloads ................................ 15
80 2.3.2 Generic payloads .................................... 15
81 2.3.2.1 ID Payload .................................. 15
82 2.3.2.2 Argument Payload ............................ 16
83 2.3.2.3 Argument List Payload ....................... 17
84 2.3.2.4 Channel Payload ............................. 18
85 2.3.2.5 Public Key Payload .......................... 19
86 2.3.2.6 Message Payload ............................. 19
87 2.3.3 Disconnect Payload .................................. 23
88 2.3.4 Success Payload ..................................... 23
89 2.3.5 Failure Payload ..................................... 24
90 2.3.6 Reject Payload ...................................... 24
91 2.3.7 Notify Payload ...................................... 25
92 2.3.8 Error Payload ....................................... 34
93 2.3.9 Channel Message Payload ............................. 34
94 2.3.10 Channel Key Payload ................................ 35
95 2.3.11 Private Message Payload ............................ 37
96 2.3.12 Private Message Key Payload ........................ 37
97 2.3.13 Command Payload .................................... 39
98 2.3.14 Command Reply Payload .............................. 40
99 2.3.15 Connection Auth Request Payload .................... 40
100 2.3.16 New ID Payload ..................................... 41
101 2.3.17 New Client Payload ................................. 42
102 2.3.18 New Server Payload ................................. 43
103 2.3.19 New Channel Payload ................................ 44
104 2.3.20 Key Agreement Payload .............................. 45
105 2.3.21 Resume Router Payload .............................. 46
106 2.3.22 File Transfer Payload .............................. 46
107 2.3.23 Resume Client Payload .............................. 48
108 2.4 SILC ID Types ............................................. 49
109 2.5 Packet Encryption And Decryption .......................... 49
110 2.5.1 Normal Packet Encryption And Decryption ............. 50
111 2.5.2 Channel Message Encryption And Decryption ........... 50
112 2.5.3 Private Message Encryption And Decryption ........... 51
113 2.6 Packet MAC Generation ..................................... 52
114 2.7 Packet Padding Generation ................................. 52
115 2.8 Packet Compression ........................................ 53
116 2.9 Packet Sending ............................................ 53
117 2.10 Packet Reception ......................................... 54
118 2.11 Packet Routing ........................................... 54
119 2.12 Packet Broadcasting ...................................... 55
120 3 Security Considerations ....................................... 56
121 4 References .................................................... 56
122 5 Author's Address .............................................. 58
123 6 Full Copyright Statement ...................................... 58
129 Figure 1: Typical SILC Packet
130 Figure 2: SILC Packet Header
132 Figure 4: Argument Payload
133 Figure 5: Argument List Payload
134 Figure 6: Channel Payload
135 Figure 7: Public Key Payload
136 Figure 8: Message Payload
137 Figure 9: Disconnect Payload
138 Figure 10: Success Payload
139 Figure 11: Failure Payload
140 Figure 12: Reject Payload
141 Figure 13: Notify Payload
142 Figure 14: Error Payload
143 Figure 15: Channel Key Payload
144 Figure 16: Private Message Key Payload
145 Figure 17: Command Payload
146 Figure 18: Connection Auth Request Payload
147 Figure 19: New Client Payload
148 Figure 20: New Server Payload
149 Figure 21: Key Agreement Payload
150 Figure 22: Resume Router Payload
151 Figure 23: File Transfer Payload
152 Figure 24: Resume Client Payload
158 This document describes a Packet Protocol used in the Secure Internet
159 Live Conferencing (SILC) protocol specified in the Secure Internet Live
160 Conferencing, Protocol Specification [SILC1]. This protocol describes
161 the packet types and packet payloads which defines the contents of the
162 packets. The protocol provides secure binary packet protocol that
163 assures that the contents of the packets are secured and authenticated.
164 The packet protocol is designed to be compact to avoid unnecessary
165 overhead as much as possible. This makes the SILC suitable also in
166 environment of low bandwidth requirements such as mobile networks. All
167 packet payloads can also be compressed to further reduce the size of
170 All packets in SILC network are always encrypted and their integrity
171 is assured by computed MACs. The protocol defines several packet types
172 and packet payloads. Each packet type usually has a specific packet
173 payload that actually defines the contents of the packet. Each packet
174 also includes a default SILC Packet Header that provides sufficient
175 information about the origin and the destination of the packet.
179 1.1 Requirements Terminology
181 The keywords MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT, RECOMMENDED,
182 MAY, and OPTIONAL, when they appear in this document, are to be
183 interpreted as described in [RFC2119].
187 2 SILC Packet Protocol
192 SILC packets deliver messages from sender to receiver securely by
193 encrypting important fields of the packet. The packet consists of
194 default SILC Packet Header, Padding, Packet Payload data, and, packet
197 The following diagram illustrates typical SILC packet.
201 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
202 | n bytes | 1 - n bytes | n bytes | n bytes
203 | SILC Header | Padding | Data Payload | MAC
204 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
208 Figure 1: Typical SILC Packet
211 SILC Header is always the first part of the packet and its purpose
212 is to provide information about the packet. It provides for example
213 the packet type, origin of the packet and the destination of the packet.
214 The header is variable in length. See the following section for
215 description of SILC Packet header. Packets without SILC header or
216 with malformed SILC header MUST be dropped.
218 Padding follows the packet header. The purpose of the padding is to
219 make the packet multiple by eight (8) or by the block size of the
220 cipher used in the encryption, which ever is larger. The maximum
221 length of padding is currently 128 bytes. The padding is always
222 encrypted. The padding is applied always, even if the packet is
223 not encrypted. See the section 2.7 Padding Generation for more
224 detailed information.
226 Data payload area follows padding and it is the actual data of the
227 packet. The packet data is the packet payloads defined in this
228 protocol. The data payload area is always encrypted.
230 The last part of SILC packet is the packet MAC that assures the
231 integrity of the packet. See the section 2.6 Packet MAC Generation
232 for more information. If compression is used the compression is
233 always applied before encryption.
235 All fields in all packet payloads are always in MSB (most significant
240 2.2 SILC Packet Header
242 The SILC packet header is applied to all SILC packets and it is
243 variable in length. The purpose of SILC Packet header is to provide
244 detailed information about the packet. The receiver of the packet
245 uses the packet header to parse the packet and gain other relevant
246 parameters of the packet.
248 The following diagram represents the SILC packet header.
253 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
254 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
255 | Payload Length | Flags | Packet Type |
256 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
257 | Pad Length | RESERVED | Source ID Len | Dest ID Len |
258 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
264 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
270 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
274 Figure 2: SILC Packet Header
277 o Payload Length (2 bytes) - Indicates the length of the
278 packet not including the padding of the packet.
280 o Flags (1 byte) - Indicates flags to be used in packet
281 processing. Several flags may be set by ORing the flags
284 The following flags are reserved for this field:
289 In this case the field is ignored.
292 Private Message Key 0x01
294 Indicates that the packet data MUST include private
295 message that is encrypted using private key set by
296 client. Servers does not know this key and cannot
297 handle the packet, but passes it along. See section
298 2.5.3 Private Message Encryption And Decryption for
304 Indicates that the packet consists of list of
305 packet payloads indicated by the Packet Type field.
306 The payloads are added one after the other. Note that
307 there are packet types that must not be used as
308 list. Parsing of list packet is done by calculating
309 the length of each payload and parsing them one by
315 Marks the packet to be broadcasted. Client and normal
316 server cannot send broadcast packets. Only router server
317 may send broadcast packet. The router receiving of packet
318 with this flag set MUST send (broadcast) the packet to
319 its primary route. If router has several router connections
320 the packet may be sent only to the primary route. See
321 section 2.12 Packet Broadcasting for description of
327 Marks that the payload of the packet is compressed.
328 The sender of the packet marks this flag when it
329 compresses the payload, and any server or router
330 en route to the recipient MUST NOT unset this flag.
331 See section 2.8 Packet Compression for description of
336 o Packet Type (1 byte) - Indicates the type of the packet.
337 Receiver uses this field to parse the packet. See section
338 2.3 SILC Packets for list of defined packet types.
340 o Pad Length (1 byte) - Indicates the length of the padding
341 applied after the SILC Packet header. Maximum length for
342 padding is 128 bytes.
344 o RESERVED (1 byte) - Reserved field and must include a
347 o Source ID Length (1 byte) - Indicates the length of the
348 Source ID field in the header, not including this or any
351 o Destination ID Length (1 byte) - Indicates the length of the
352 Destination ID field in the header, not including this or
355 o Src ID Type (1 byte) - Indicates the type of ID in the
356 Source ID field. See section 2.4 SILC ID Types for
359 o Source ID (variable length) - The actual source ID that
360 indicates which is the original sender of the packet.
362 o Dst ID Type (1 byte) - Indicates the type of ID in the
363 Destination ID field. See section 2.4 SILC ID Types for
366 o Destination ID (variable length) - The actual destination
367 ID that indicates which is the end receiver of the packet.
372 2.3 SILC Packet Types
374 SILC packet types defines the contents of the packet and it is used by
375 the receiver to parse the packet. The packet type is 8 bits in length.
376 The range for the packet types are from 0 - 255, where 0 is never sent and
377 255 is currently reserved for future extensions and MUST NOT be defined to
378 any other purpose. Every SILC specification compliant implementation
379 SHOULD support all the following packet types.
381 The below list of the SILC Packet types includes reference to the packet
382 payload as well. Packet payloads are the actual packet data area. Each
383 packet type defines packet payload which usually may only be sent with
384 the specific packet type.
386 Most of the packets are packets that must be destined directly to entity
387 that is connected to the sender. It is not allowed, for example, for a
388 router to send SILC_PACKET_DISCONNECT packet to client that is not
389 directly connected to the router. However, there are some special packet
390 types that may be destined to some entity that the sender does not have
391 direct connection with. These packets are for example private message
392 packets, channel message packets, command packets and some other packets
393 that may be broadcasted in the SILC network. If the packet is allowed to
394 be sent to indirectly connected entity it is defined separately in the
395 following packet description list. Other packets MUST NOT be sent or
396 accepted, if sent, to indirectly connected entities.
398 Some packets MAY be sent as lists by adding the List flag to the Packet
399 Header and constructing multiple packet payloads one after the other.
400 When this is allowed it is separately defined in the following list.
401 Other packets MUST NOT be sent as list and the List flag MUST NOT be set.
404 List of SILC Packet types are defined as follows.
409 This type is reserved and it is never sent.
412 1 SILC_PACKET_DISCONNECT
414 This packet is sent to disconnect the remote end. Reason of
415 the disconnection is sent inside the packet payload.
417 Payload of the packet: See section 2.3.3 Disconnect Payload
420 2 SILC_PACKET_SUCCESS
422 This packet is sent upon successful execution of a protocol.
423 The status of the success is sent in the packet payload.
425 Payload of the packet: See section 2.3.4 Success Payload
428 3 SILC_PACKET_FAILURE
430 This packet is sent upon failure of a protocol. The status
431 of the failure is sent in the packet payload.
433 Payload of the packet: See section 2.3.5 Failure Payload
438 This packet MAY be sent upon rejection of a protocol. The
439 status of the rejection is sent in the packet payload.
441 Payload of the packet: See section 2.3.6 Reject Payload
446 This packet is used to send notify message. The packet is
447 usually sent between server and client, but also between
448 server and router. Client MUST NOT send this packet. Server
449 MAY destine this packet to channel as well when the packet is
450 distributed to all clients on the channel. This packet MAY
453 Payload of the packet: See section 2.3.7 Notify Payload.
458 This packet is sent when an error occurs. Server MAY
459 send this packet. Client MUST NOT send this packet. The
460 client MAY entirely ignore the packet, however, server is
461 most likely to take action anyway. This packet MAY be sent
462 to entity that is indirectly connected to the sender.
464 Payload of the packet: See section 2.3.8 Error Payload.
467 7 SILC_PACKET_CHANNEL_MESSAGE
469 This packet is used to send messages to channels. The packet
470 includes Channel ID of the channel and the actual message to
471 the channel. Messages sent to the channel are always protected
472 by channel specific keys. This packet MAY be sent to entity
473 that is indirectly connected to the sender.
475 Payload of the packet: See section 2.3.9 Channel Message
479 8 SILC_PACKET_CHANNEL_KEY
481 This packet is used to distribute new key for particular
482 channel when server generates it. Each channel has their own
483 independent keys that is used to protect the traffic on the
484 channel. It is also possible to use channel private keys that
485 are not server generated. In this case this packet is not used.
486 Client MUST NOT send this packet. This packet MAY be sent to
487 entity that is indirectly connected to the sender.
489 Payload of the packet: See section 2.3.10 Channel Key Payload
492 9 SILC_PACKET_PRIVATE_MESSAGE
494 This packet is used to send private messages from client
495 to another client. By default, private messages are protected
496 by session keys established by normal key exchange protocol.
497 However, it is possible to use specific key to protect private
498 messages. See [SILC1] for private message key generation.
499 This packet MAY be sent to entity that is indirectly connected
502 Payload of the packet: See section 2.3.11 Private Message
506 10 SILC_PACKET_PRIVATE_MESSAGE_KEY
508 This packet can be used to agree about a key to be used to
509 protect private messages between two clients. This packet
510 is sent inside the SILC network and protected with session
511 keys. There are other means of agreeing to use private message
512 keys as well, than sending this packet which may not be
513 desirable on all situations. See the [SILC1] for private
514 message key generation.
516 Payload of the packet: See section 2.3.12 Private Message
520 11 SILC_PACKET_COMMAND
522 This packet is used to send commands from client to server.
523 Server MAY send this packet to other servers as well. All
524 commands are listed in their own section SILC Command Types
525 in [SILC4]. The contents of this packet is command specific.
526 This packet MAY be sent to entity that is indirectly connected
529 Payload of the packet: See section 2.3.13 Command Payload
532 12 SILC_PACKET_COMMAND_REPLY
534 This packet is sent as reply to the SILC_PACKET_COMMAND packet.
535 The contents of this packet is command specific. This packet
536 MAY be sent to entity that is indirectly connected to the
537 sender. This packet MAY be sent as list.
539 Payload of the packet: See section 2.3.14 Command Reply
540 Payload and section 2.3.13 Command
545 13 SILC_PACKET_KEY_EXCHANGE
547 This packet is used to start SILC Key Exchange Protocol,
548 described in detail in [SILC3].
550 Payload of the packet: Payload of this packet is described
551 in the section SILC Key Exchange
552 Protocol and its sub sections in
556 14 SILC_PACKET_KEY_EXCHANGE_1
558 This packet is used as part of the SILC Key Exchange Protocol.
560 Payload of the packet: Payload of this packet is described
561 in the section SILC Key Exchange
562 Protocol and its sub sections in
566 15 SILC_PACKET_KEY_EXCHANGE_2
568 This packet is used as part of the SILC Key Exchange Protocol.
570 Payload of the packet: Payload of this packet is described
571 in the section SILC Key Exchange
572 Protocol and its sub sections in
576 16 SILC_PACKET_CONNECTION_AUTH_REQUEST
578 This packet is used to request an authentication method to
579 be used in the SILC Connection Authentication Protocol. If
580 initiator of the protocol does not know the mandatory
581 authentication method this packet MAY be used to determine it.
582 The party receiving this payload SHOULD respond with the same
583 packet including the mandatory authentication method.
585 Payload of the packet: See section 2.3.15 Connection Auth
589 17 SILC_PACKET_CONNECTION_AUTH
591 This packet is used to start and perform the SILC Connection
592 Authentication Protocol. This protocol is used to authenticate
593 the connecting party. The protocol is described in detail in
596 Payload of the packet: Payload of this packet is described
597 in the section SILC Authentication
598 Protocol and it sub sections in [SILC].
601 18 SILC_PACKET_NEW_ID
603 This packet is used to distribute new IDs from server to
604 router and from router to all other routers in SILC network.
605 This is used when for example new client is registered to
606 SILC network. The newly created IDs of these operations are
607 distributed by this packet. Only server may send this packet,
608 however, client MUST be able to receive this packet. This
609 packet MAY be sent to entity that is indirectly connected
610 to the sender. This packet MAY be sent as list.
612 Payload of the packet: See section 2.3.16 New ID Payload
615 19 SILC_PACKET_NEW_CLIENT
617 This packet is used by client to register itself to the
618 SILC network. This is sent after key exchange and
619 authentication protocols has been completed. Client sends
620 various information about itself in this packet to the server.
622 Payload of the packet: See section 2.3.17 New Client Payload
625 20 SILC_PACKET_NEW_SERVER
627 This packet is used by server to register itself to the
628 SILC network. This is sent after key exchange and
629 authentication protocols has been completed. Server sends
630 this to the router it connected to, or, if router was
631 connecting, to the connected router. Server sends its
632 Server ID and other information in this packet. The client
633 MUST NOT send or receive this packet.
635 Payload of the packet: See section 2.3.18 New Server Payload
638 21 SILC_PACKET_NEW_CHANNEL
640 This packet is used to notify routers about newly created
641 channel. Channels are always created by the router and it MUST
642 notify other routers about the created channel. Router sends
643 this packet to its primary route. Client MUST NOT send this
644 packet. This packet MAY be sent to entity that is indirectly
645 connected to the sender. This packet MAY be sent as list.
647 Payload of the packet: See section 2.3.19 New Channel Payload
652 This packet is used to indicate that re-key must be performed
653 for session keys. See section Session Key Regeneration in
654 [SILC1] for more information. This packet does not have
658 23 SILC_PACKET_REKEY_DONE
660 This packet is used to indicate that re-key is performed and
661 new keys must be used hereafter. This packet does not have a
665 24 SILC_PACKET_HEARTBEAT
667 This packet is used by clients, servers and routers to keep the
668 connection alive. It is RECOMMENDED that all servers implement
669 keepalive actions and perform it to both direction in a link.
670 This packet does not have a payload.
673 25 SILC_PACKET_KEY_AGREEMENT
675 This packet is used by clients to request key negotiation
676 between another client in the SILC network. If the negotiation
677 is started it is performed using the SKE protocol. The result of
678 the negotiation, the secret key material, can be used for
679 example as private message key. The server and router MUST NOT
682 Payload of the packet: See section 2.3.20 Key Agreement Payload
685 26 SILC_PACKET_RESUME_ROUTER
687 This packet is used during backup router protocol when the
688 original primary router of the cell comes back online and wishes
689 to resume the position as being the primary router of the cell.
691 Payload of the packet: See section 2.3.21 Resume Router Payload
696 This packet is used to perform an file transfer protocol in the
697 SILC session with some entity in the network. The packet is
698 multi purpose. The packet is used to tell other entity in the
699 network that the sender wishes to perform an file transfer
700 protocol. The packet is also used to actually tunnel the
701 file transfer protocol stream. The file transfer protocol
702 stream is always protected with the SILC binary packet protocol.
704 Payload of the packet: See section 2.3.22 File Transfer Payload
707 28 SILC_PACKET_RESUME_CLIENT
709 This packet is used to resume a client back to the network
710 after it has been detached. A client is able to detach from
711 the network but the client is still valid client in the network.
712 The client may then later resume its session back by sending
713 this packet to a server. Routers also use this packet to notify
714 other routers in the network that the detached client has resumed.
716 Payload of the packet: See section 2.3.23 Resume Client Payload
721 Currently undefined commands.
726 These packet types are reserved for private use and they will
727 not be defined by this document.
732 This type is reserved for future extensions and currently it
738 2.3.1 SILC Packet Payloads
740 All payloads resides in the main data area of the SILC packet. However
741 all payloads MUST be at the start of the data area after the SILC
742 packet header and padding. All fields in the packet payload are always
743 encrypted, as they reside in the data area of the packet which is
744 always encrypted. Most of the payloads may only be sent with specific
745 packet type which is defined in the description of the payload.
747 There are some other payloads in SILC as well. However, they are not
748 common in the sense that they could be sent at any time. These payloads
749 are not described in this section. These are payloads such as SILC
750 Key Exchange payloads and so on. These are described in [SILC1],
755 2.3.2 Generic payloads
757 This section describes generic payloads that are not associated to any
758 specific packet type. They can be used for example inside some other
765 This payload can be used to send an ID. ID's are variable in length
766 thus this payload provides a way to send variable length ID.
768 The following diagram represents the ID Payload.
773 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
774 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
775 | ID Type | ID Length |
776 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
780 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
788 o ID Type (2 bytes) - Indicates the type of the ID. See
789 section 2.4 SILC ID Types for list of defined ID types.
791 o ID Length (2 bytes) - Length of the ID Data area not
792 including the length of any other fields in the payload.
794 o ID Data (variable length) - The actual ID data. The encoding
795 of the ID data is defined in section 2.4 SILC ID Types.
800 2.3.2.2 Argument Payload
802 Argument Payload is used to set arguments for any packet payload that
803 need and support arguments, such as commands. Number of arguments
804 associated with a packet MUST be indicated by the packet payload which
805 need the arguments. Argument Payloads MUST always reside right after
806 the packet payload needing the arguments. Incorrect amount of argument
807 payloads MUST cause rejection of the packet.
809 The following diagram represents the Argument Payload.
814 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
815 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
816 | Payload Length | Argument Type | |
817 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
821 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
825 Figure 4: Argument Payload
829 o Payload Length (2 bytes) - Length of the Argument Data
830 field not including the length of any other field in the
833 o Argument Type (1 byte) - Indicates the type of the argument.
834 Every argument can have a specific type that are defined
835 by the packet payload needing the argument. For example
836 every command specify a number for each argument that may be
837 associated with the command. By using this number the receiver
838 of the packet knows what type of argument this is. If there is
839 no specific argument type this field is set to zero (0) value.
841 o Argument Data (variable length) - Argument data.
846 2.3.2.3 Argument List Payload
848 Argument List Payload is a list of Argument Payloads appended one
849 after the other. The number of arguments is indicated in the
852 The following diagram represents the Argument List Payload.
857 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
858 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
860 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
862 ~ Argument Payloads ~
864 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
868 Figure 5: Argument List Payload
872 o Argument Nums (2 bytes) - Indicates the number of Argument
873 Payloads. If zero (0) value is found in this field no
874 arguments are present.
876 o Argument Payloads (variable length) - The Argument Payloads
877 appended one after the other. The payloads can be decoded
878 since the length of the payload is indicated in each of
879 the Argument Payload.
886 2.3.2.4 Channel Payload
888 Generic Channel Payload may be used to send information about a channel,
889 its name, the Channel ID and a mode.
891 The following diagram represents the Channel Payload.
897 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
898 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
899 | Channel Name Length | |
900 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
904 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
905 | Channel ID Length | |
906 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
910 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
912 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
916 Figure 6: New Channel Payload
920 o Channel Name Length (2 bytes) - Length of the Channel Name
923 o Channel Name (variable length) - The name of the channel.
925 o Channel ID Length (2 bytes) - Length of the Channel ID field.
927 o Channel ID (variable length) - The encoded Channel ID.
929 o Mode Mask (4 bytes) - A mode. This can be the mode of the
930 channel but it can also be the mode of a client on the
931 channel. The contents of this field is dependent of the
932 usage of this payload. The usage is defined separately
933 when this payload is used. This is a 32 bit MSB first value.
942 2.3.2.5 Public Key Payload
944 Generic Public Key Payload may be used to send different type of
945 public keys and certificates.
947 The following diagram represents the Public Key Payload.
952 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
953 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
954 | Public Key Length | Public Key Type |
955 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
957 ~ Public Key (or certificate) ~
959 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
963 Figure 7: Public Key Payload
967 o Public Key Length (2 bytes) - The length of the Public Key
968 (or certificate) field, not including any other field.
970 o Public Key Type (2 bytes) - The public key (or certificate)
971 type. This field indicates the type of the public key in
972 the packet. See the [SILC3] for defined public key types.
974 o Public Key (or certificate) (variable length) - The
975 encoded public key or certificate data.
980 2.3.2.6 Message Payload
982 Generic Message Payload can be used to send messages in SILC. It
983 is used to send channel messages and private messages.
985 The following diagram represents the Message Payload.
987 (*) indicates that the field is not encrypted.
1000 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
1001 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1002 | Message Flags | Message Length |
1003 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1007 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1008 | Padding Length | |
1009 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1013 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1015 ~ Initial Vector * ~
1017 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1021 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1025 Figure 8: Message Payload
1029 o Message Flags (2 bytes) - Includes the Message Flags of the
1030 message. The flags can indicate a reason or a purpose for
1031 the message. The following Message Flags are defined:
1033 0x0000 SILC_MESSAGE_FLAG_NONE
1035 No specific flags set.
1037 0x0001 SILC_MESSAGE_FLAG_AUTOREPLY
1039 This message is an automatic reply to an earlier
1042 0x0002 SILC_MESSAGE_FLAG_NOREPLY
1044 There should not be reply messages to this
1047 0x0004 SILC_MESSAGE_FLAG_ACTION
1049 The sender is performing an action and the message
1050 is the indication of the action.
1052 0x0008 SILC_MESSAGE_FLAG_NOTICE
1054 The message is for example an informational notice
1057 0x0010 SILC_MESSAGE_FLAG_REQUEST
1059 This is a generic request flag to send request
1060 messages. A separate document should define any
1061 payloads associated to this flag.
1063 0x0020 SILC_MESSAGE_FLAG_SIGNED
1065 This flag indicates that the message is signed
1066 with sender's private key and thus can be verified
1067 by the receiver using the sender's public key. A
1068 separate document should define the detailed procedure
1069 of the signing process and any associated payloads
1072 0x0040 SILC_MESSAGE_FLAG_REPLY
1074 This is a generic reply flag to send a reply to
1075 previously received request. A separate document
1076 should define any payloads associated to this flag.
1078 0x0080 SILC_MESSAGE_FLAG_DATA
1080 This is a generic data flag, indicating that the
1081 message includes some data which can be interpreted
1082 in a specific way. Using this flag any kind of data
1083 can be delivered inside message payload. A separate
1084 document should define how this flag is interpreted
1085 and define any associated payloads.
1087 0x0100 SILC_MESSAGE_FLAG_UTF8
1089 This flag indicates that the message is UTF-8 encoded
1090 textual message. When sending text messages in SILC
1091 this flag SHOULD be used. When this flag is used the
1092 text sent as message MUST be UTF-8 encoded.
1094 0x0200 - 0x0800 RESERVED
1096 Reserved for future flags.
1098 0x1000 - 0x8000 PRIVATE RANGE
1100 Private range for free use.
1102 o Message Length (2 bytes) - Indicates the length of the
1103 Message Data field in the payload, not including any
1106 o Message Data (variable length) - The actual message data.
1108 o Padding Length (2 bytes) - Indicates the length of the
1109 Padding field in the payload, not including any other
1112 o Padding (variable length) - If this payload is used as
1113 channel messages, the padding MUST be applied because
1114 this payload is encrypted separately from other parts
1115 of the packet. If this payload is used as private
1116 messages, the padding is present only when the payload
1117 is encrypted with private message key. If encrypted
1118 with session keys this field MUST NOT be present and the
1119 Padding Length field includes a zero (0) value. The
1120 padding SHOULD be random data.
1122 o Initial Vector (variable length) - This field MUST be
1123 present when this payload is used as channel messages.
1124 The IV SHOULD be random data for each channel message.
1126 When encrypting private messages with session keys this
1127 field MUST NOT be present. For private messages this
1128 field is present only when encrypting with a static
1129 private message key (pre-shared key). If randomly
1130 generated key material is used this field MUST NOT be
1131 present. Also, If Key Agreement (SKE) was used to
1132 negotiate fresh key material for private message key
1133 this field MUST NOT be present. See the section 4.6
1134 in [SILC1] for more information about IVs when
1135 encrypting private messages.
1137 This field includes the initial vector used in message
1138 encryption. It need to be used in the packet decryption
1139 as well. Contents of this field depends on the encryption
1140 algorithm and encryption mode. This field is not encrypted,
1141 is not included in padding calculation and its length
1142 equals to cipher's block size. This field is authenticated
1145 o MAC (variable length) - The MAC computed from the
1146 Message Flags, Message Length, Message Data, Padding Length,
1147 Padding and Initial Vector fields in that order. The MAC
1148 is computed after the payload is encrypted. This is so
1149 called Encrypt-Then-MAC order; first encrypt, then compute
1150 MAC from ciphertext. The MAC protects the integrity of
1151 the Message Payload. Also, when used as channel messages
1152 it is possible to have multiple private channel keys set,
1153 and receiver can use the MAC to verify which of the keys
1154 must be used in decryption. This field is not encrypted.
1155 This field is authenticated by the SILC packet MAC.
1160 2.3.3 Disconnect Payload
1162 Disconnect payload is sent upon disconnection. Reason of the
1163 disconnection is sent to the disconnected party in the payload.
1165 The payload may only be sent with SILC_PACKET_DISCONNECT packet. It
1166 MUST NOT be sent in any other packet type. The following diagram
1167 represents the Disconnect Payload.
1173 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
1174 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1178 ~ Disconnect Message ~
1180 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1184 Figure 9: Disconnect Payload
1187 o Status (1 byte) - Indicates the Status Type, defined in [SILC3]
1188 for the reason of disconnection.
1190 o Disconnect Message (variable length) - Human readable UTF-8
1191 encoded string indicating reason of the disconnection. This
1192 field MAY be omitted.
1197 2.3.4 Success Payload
1199 Success payload is sent when some protocol execution is successfully
1200 completed. The payload is simple; indication of the success is sent.
1201 This may be any data, including binary or human readable data, and
1202 it is protocol dependent.
1207 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
1208 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1210 ~ Success Indication ~
1212 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1216 Figure 10: Success Payload
1220 o Success Indication (variable length) - Indication of
1221 the success. This may be for example some flag that
1222 indicates the protocol and the success status or human
1223 readable success message. The true length of this
1224 payload is available by calculating it from the SILC
1230 2.3.5 Failure Payload
1232 This is opposite of Success Payload. Indication of failure of
1233 some protocol is sent in the payload.
1238 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
1239 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1241 ~ Failure Indication ~
1243 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1247 Figure 11: Failure Payload
1251 o Failure Indication (variable length) - Indication of
1252 the failure. This may be for example some flag that
1253 indicates the protocol and the failure status or human
1254 readable failure message. The true length of this
1255 payload is available by calculating it from the SILC
1261 2.3.6 Reject Payload
1263 This payload is sent when some protocol is rejected to be executed.
1264 Other operations MAY send this as well that was rejected. The
1265 indication of the rejection is sent in the payload. The indication
1266 may be binary or human readable data and is protocol dependent.
1272 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
1273 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1275 ~ Reject Indication ~
1277 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1281 Figure 12: Reject Payload
1285 o Reject Indication (variable length) - Indication of
1286 the rejection. This maybe for example some flag that
1287 indicates the protocol and the rejection status or human
1288 readable rejection message. The true length of this
1289 payload is available by calculating it from the SILC
1296 2.3.7 Notify Payload
1298 Notify payload is used to send notify messages. The payload is usually
1299 sent from server to client and from server to router. It is also used
1300 by routers to notify other routers in the network. This payload MAY also
1301 be sent to a channel. Client MUST NOT send this payload. When this
1302 packet is received by client it SHOULD process it. Servers and routers
1303 MUST process notify packets.
1305 The payload may only be sent with SILC_PACKET_NOTIFY packet. It MUST
1306 NOT be sent in any other packet type. The following diagram represents
1314 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
1315 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1316 | Notify Type | Payload Length |
1317 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1323 Figure 13: Notify Payload
1327 o Notify Type (2 bytes) - Indicates the type of the notify
1330 o Payload Length (2 bytes) - Length of the entire Notify Payload
1331 including any associated Argument Payloads.
1333 o Argument Nums (1 byte) - Indicates the number of Argument
1334 Payloads associated to this payload. Notify types may define
1335 arguments to be sent along the notify message.
1338 The following list of currently defined notify types. The format for
1339 notify arguments is same as in SILC commands described in [SILC4].
1340 Note that all IDs sent in arguments are sent inside ID Payload. Also
1341 note that all passphrases that may be sent inside arguments MUST be
1342 UTF-8 [RFC2279] encoded. Also note that all public keys or certificates
1343 sent inside arguments are actually Public Key Payloads.
1347 0 SILC_NOTIFY_TYPE_NONE
1349 If no specific notify type apply for the notify message this type
1353 Arguments: (1) <message>
1355 The <message> is implementation specific free UTF-8 text string.
1356 Receiver MAY ignore this message.
1359 1 SILC_NOTIFY_TYPE_INVITE
1361 Sent when an client is invited to a channel. This is also sent
1362 when the invite list of the channel is changed. This notify type
1363 is sent between routers and if an client was invited, to the
1364 client as well. In this case the packet is destined to the
1368 Arguments: (1) <Channel ID> (2) <channel name>
1369 (3) [<sender Client ID>] (4) [<add | del>]
1372 The <Channel ID> is the channel. The <channel name> is the name
1373 of the channel and is provided because the client which receives
1374 this notify packet may not have a way to resolve the name of the
1375 channel from the <Channel ID>. The <sender Client ID> is the
1376 Client ID which invited the client to the channel. The
1377 <add | del> is an argument of size of 1 byte where 0x00 means
1378 adding a client to invite list, and 0x01 means deleting a client
1379 from invite list. The <invite list>, if present, indicates the
1380 information to be added to or removed from the invite list.
1381 The <invite list> format is defined in [SILC4] with
1382 SILC_COMMAND_INVITE command. When this notify is destined to
1383 a client the <add | del> and <invite list> MUST NOT be sent.
1386 2 SILC_NOTIFY_TYPE_JOIN
1388 Sent when client has joined to a channel. The server MUST
1389 distribute this type to the local clients on the channel and then
1390 send it to its primary router. Note that, when router is joining
1391 the client on behalf of normal server then router MUST send this
1392 notify type locally and globally. The router or server receiving
1393 the packet distributes this type to the local clients on the
1394 channel and broadcast it to the network. This notify is sent
1395 also to the client that joined the channel.
1398 Arguments: (1) [<Client ID>] (2) <Channel ID>
1400 The <Client ID> is the client that joined to the channel
1401 indicated by the <Channel ID>.
1404 3 SILC_NOTIFY_TYPE_LEAVE
1406 Sent when client has left a channel. The server must distribute
1407 this type to the local clients on the channel and then send it
1408 to its primary router. The router or server receiving the
1409 packet distributes this type to the local clients on the channel
1410 and broadcast it to the network. This notify MUST NOT be sent to
1414 Arguments: (1) <Client ID>
1416 The <Client ID> is the client which left the channel.
1419 4 SILC_NOTIFY_TYPE_SIGNOFF
1421 Sent when client signoff from SILC network. The server MUST
1422 distribute this type to the local clients on the channel and
1423 then send it to its primary router. The router or server
1424 receiving the packet distributes this type to the local clients
1425 on the channel and broadcast it to the network. This notify
1426 MUST NOT be sent to the quitting client.
1429 Arguments: (1) <Client ID> (2) <message>
1431 The <Client ID> is the client which left SILC network. The
1432 <message> is free text string indicating the reason of the
1436 5 SILC_NOTIFY_TYPE_TOPIC_SET
1438 Sent when topic is set/changed on a channel. This type may be
1439 sent only to the clients which are joined on the channel which
1440 topic was just set or changed. The packet is destined to the
1444 Arguments: (1) <ID Payload> (2) <topic>
1446 The <ID Payload> is the ID of the entity who set the topic.
1447 It usually is Client ID but it can be Server ID and Channel ID
1451 6 SILC_NOTIFY_TYPE_NICK_CHANGE
1453 Sent when client changes nick on a channel. The server MUST
1454 distribute this type only to the local clients on the channel
1455 and then send it to its primary router. The router or server
1456 receiving the packet distributes this type to the local clients
1457 on the channel and broadcast it to the network. This packet is
1458 destined directly to the sent entity. This MUST be sent to those
1459 clients that are joined on same channels as the client that
1460 changed the nickname. This notify MUST NOT be sent multiple
1461 times to the same recipient. This notify MUST be sent also to
1462 the client that changed the nickname.
1465 Arguments: (1) <Old Client ID> (2) <New Client ID>
1468 The <Old Client ID> is the old ID of the client which changed
1469 the nickname. The <New Client ID> is the new ID generated by
1470 the change of the nickname. The <nickname> is the new nickname.
1471 Note that it is possible to send this notify even if the
1472 nickname has not changed, but client ID was changed.
1475 7 SILC_NOTIFY_TYPE_CMODE_CHANGE
1477 Sent when channel mode has changed. This type MUST be sent only
1478 to the clients which are joined on the channel which mode was
1479 changed. This packet is destined to the channel.
1482 Arguments: (1) <ID Payload> (2) <mode mask>
1483 (3) [<cipher>] (4) <[hmac>]
1484 (5) [<passphrase>] (6) [<founder public key>]
1485 (7) [<add | del>] (8) [<channel public key>]
1487 The <ID Payload> is the ID (usually Client ID but it can be
1488 Server ID as well when the router is enforcing channel mode
1489 change) of the entity which changed the mode. The <mode mask>
1490 is the new mode mask of the channel. The client can safely
1491 ignore the <cipher> argument since the SILC_PACKET_CHANNEL_KEY
1492 packet will force the new channel key change anyway. The <hmac>
1493 argument is important since the client is responsible of setting
1494 the new HMAC and the hmac key into use. The <passphrase> is
1495 the passphrase of the channel, if it was now set. The <founder
1496 public key> argument is sent when the founder mode on the
1497 channel was set. All routers and servers that receive the packet
1498 MUST save the founder's public key so that the founder can
1499 reclaim the channel founder rights back for the channel on any
1500 server in the network.
1502 The <add | del> and <channel public key> is used to add or
1503 remove channel public key from the channel. To add one public
1504 key to channel the SILC_CMODE_CHANNEL_AUTH mode is set and the
1505 <add | del> argument includes 0x00 value, and the <channel
1506 public key> is the public key. To remove one public key from
1507 channel public key list the <add | del> includes 0x01 value and
1508 <channel pubkey> is the public key to be removed. If the
1509 SILC_CMODE_CHANNEL_AUTH mode is unset (and was set earlier)
1510 all public keys are removed at once.
1513 8 SILC_NOTIFY_TYPE_CUMODE_CHANGE
1515 Sent when user mode on channel has changed. This type MUST be
1516 sent only to the clients which are joined on the channel where
1517 the target client is on. This packet is destined to the channel.
1520 Arguments: (1) <ID Payload> (2) <mode mask>
1521 (3) <Target Client ID> (4) [<founder pubkey>]
1523 The <ID Payload> is the ID (usually Client ID but it can be
1524 Server ID as well when the router is enforcing user's mode
1525 change) of the entity which changed the mode. The <mode mask>
1526 is the new mode mask of the channel. The <Target Client ID>
1527 is the client which mode was changed. The <founder pubkey>
1528 is the public key of the channel founder and may be sent only
1529 when first time setting the channel founder mode using the
1530 SILC_COMMAND_CUMODE command, and when sending this notify.
1533 9 SILC_NOTIFY_TYPE_MOTD
1535 Sent when Message of the Day (motd) is sent to a client.
1538 Arguments: (1) <motd>
1540 The <motd> is the Message of the Day. This notify MAY be
1544 10 SILC_NOTIFY_TYPE_CHANNEL_CHANGE
1546 Sent when channel's ID has changed for a reason or another.
1547 This is sent by normal server to the client. This can also be
1548 sent by router to other server to force the Channel ID change.
1549 The Channel ID MUST be changed to use the new one. When sent
1550 to clients, this type MUST be sent only to the clients which are
1551 joined on the channel. This packet is destined to the sent
1555 Arguments: (1) <Old Channel ID> (2) <New Channel ID>
1557 The <Old Channel ID> is the channel's old ID and the <New
1558 Channel ID> is the new one that MUST replace the old one.
1559 Server which receives this from router MUST re-announce the
1560 channel to the router by sending SILC_PACKET_NEW_CHANNEL packet
1561 with the new Channel ID.
1564 11 SILC_NOTIFY_TYPE_SERVER_SIGNOFF
1566 Sent when server quits SILC network. Those clients from this
1567 server that are on channels must be removed from the channel.
1568 This packet is destined to the sent entity.
1571 Arguments: (1) <Server ID> (n) [<Client ID>] [...]
1573 The <Server ID> is the server's ID. The rest of the arguments
1574 are the Client IDs of the clients which are coming from this
1575 server and are thus quitting the SILC network also. If the
1576 maximum number of arguments are reached another
1577 SILC_NOTIFY_TYPE_SERVER_SIGNOFF notify packet MUST be sent.
1578 When this notify packet is sent between routers the Client ID's
1579 MAY be omitted. Server receiving the Client ID's in the payload
1580 may use them directly to remove the client.
1583 12 SILC_NOTIFY_TYPE_KICKED
1585 Sent when a client has been kicked from a channel. This MUST
1586 also be sent to the client which was kicked from the channel.
1587 The client which was kicked from the channel MUST be removed
1588 from the channel. The client MUST also be removed from channel's
1589 invite list if it is explicitly added in the list. This packet
1590 is destined to the channel. The router or server receiving the
1591 packet distributes this type to the local clients on the channel
1592 and broadcast it to the network.
1595 Arguments: (1) <Client ID> (2) [<comment>]
1596 (3) <Kicker's Client ID>
1598 The <Client ID> is the client which was kicked from the channel.
1599 The kicker may have set the <comment> to indicate the reason for
1600 the kicking. The <Kicker's Client ID> is the kicker.
1603 13 SILC_NOTIFY_TYPE_KILLED
1605 Sent when a client has been killed from the network. This MUST
1606 also be sent to the client which was killed from the network.
1607 This notify MUST be sent to those clients which are joined on
1608 same channels as the killed client. The client which was killed
1609 MUST be removed from the network. This packet is destined
1610 directly to the sent entity. The router or server receiving
1611 the packet distributes this type to the local clients on the
1612 channel and broadcast it to the network. The client MUST also
1613 be removed from joined channels invite list if it is explicitly
1614 added in the lists. This notify MUST NOT be sent multiple
1615 times to same recipient.
1618 Arguments: (1) <Client ID> (2) [<comment>]
1621 The <Client ID> is the client which was killed from the network.
1622 The killer may have set the <comment> to indicate the reason for
1623 the killing. The <Killer's ID> is the killer, which may be
1624 client but also router server.
1627 14 SILC_NOTIFY_TYPE_UMODE_CHANGE
1629 Sent when user's mode in the SILC changes. This type is sent
1630 only between routers as broadcast packet.
1633 Arguments: (1) <Client ID> (2) <mode mask>
1635 The <Client ID> is the client which mode was changed. The
1636 <mode mask> is the new mode mask.
1639 15 SILC_NOTIFY_TYPE_BAN
1641 Sent when the ban list of the channel is changed. This type is
1642 sent only between routers as broadcast packet.
1645 Arguments: (1) <Channel ID> (2) [<add | del>]
1648 The <Channel ID> is the channel which ban list was changed.
1649 The <add | del> is an argument of size of 1 byte where 0x00 means
1650 adding a client to ban list, and 0x01 means deleting a client
1651 from ban list. The <ban list> indicates the information to be
1652 added to or removed from the ban list. The <ban list> format
1653 format is defined in [SILC4] with SILC_COMMAND_BAN command.
1656 16 SILC_NOTIFY_TYPE_ERROR
1658 Sent when an error occurs during processing some SILC procedure.
1659 This is not used when error occurs during command processing, see
1660 [SILC4] for more information about commands and command replies.
1661 This type is sent directly to the sender of the packet whose
1662 packet caused the error. See [SILC1] for definition when this
1666 Arguments: (1) <Status Type> (n) [...]
1668 The <Status Type> is the error type defined in [SILC4]. Note
1669 that same types are also used with command replies to indicate
1670 the status of a command. Both commands and this notify type
1671 share same status types. Rest of the arguments are status type
1672 dependent and are specified with those status types that can be
1673 sent currently inside this notify type in [SILC4]. The <Status
1674 Type> is size of 1 byte.
1677 17 SILC_NOTIFY_TYPE_WATCH
1679 Sent to indicate change in a watched user. Client can set
1680 nicknames to be watched with SILC_COMMAND_WATCH command, and
1681 receive notifications when they login to network, signoff from
1682 the network or their user mode is changed. This notify type
1683 is used to deliver these notifications. The notify type is
1684 sent directly to the watching client.
1687 Arguments: (1) <Client ID> (2) [<nickname>]
1688 (3) <user mode> (4) [<Notify Type>]
1690 The <Client ID> is the user's Client ID which is being watched,
1691 and the <nickname> is its nickname. If the client just
1692 changed the nickname, then <nickname> is the new nickname, but
1693 the <Client ID> is the old client ID. The <user mode> is the
1694 user's current user mode. The <Notify Type> can be same as the
1695 Notify Payload's Notify Type, and is 16 bit MSB first order
1696 value. If provided it may indicate the notify that occurred
1697 for the client. If client logged in to the network the
1698 <Notify Type> MUST NOT be present.
1701 Notify types starting from 16384 are reserved for private notify
1704 Router server which receives SILC_NOTIFY_TYPE_SIGNOFF,
1705 SILC_NOTIFY_TYPE_SERVER_SIGNOFF, SILC_NOTIFY_TYPE_KILLED,
1706 SILC_NOTIFY_TYPE_NICK_CHANGE and SILC_NOTIFY_TYPE_UMODE_CHANGE
1707 MUST check whether someone in the local cell is watching the nickname
1708 the client has, and send the SILC_NOTIFY_TYPE_WATCH notify to the
1709 watcher, unless the watched client in case has the user mode
1710 SILC_UMODE_REJECT_WATCHING set. If the watcher client and the client
1711 that was watched is same the notify SHOULD NOT be sent.
1720 Error payload is sent upon error in protocol. Error may occur in
1721 various conditions when server sends this packet. Client MUST NOT
1722 send this payload but MUST be able to accept it. However, client
1723 MAY ignore the contents of the packet as server is going to take
1724 action on the error anyway. However, it is recommended that the
1725 client takes error packet seriously.
1731 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
1732 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1736 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1740 Figure 14: Error Payload
1744 o Error Message (variable length) - Human readable error
1745 message as UTF-8 string.
1750 2.3.9 Channel Message Payload
1752 Channel Message Payload is used to send message to channels, a group
1753 of users. These messages can only be sent if client has joined to
1754 some channel. Even though this packet is very common in SILC it
1755 is still special packet. Some special handling on sending and
1756 reception of channel message is required.
1758 Padding MUST be applied into this payload since the payload is
1759 encrypted separately from other parts of the packet with the
1760 channel specific key. Hence the requirement of the padding.
1761 The packet MUST be made multiple by eight (8) or by the block
1762 size of the cipher, which ever is larger.
1764 The SILC header in this packet is encrypted with the session key
1765 of the next receiver of the packet. Nothing else is encrypted
1766 with that key. Thus, the actual packet and padding to be
1767 encrypted with the session key is SILC Header plus padding to it.
1769 Receiver of the the channel message packet is able to determine
1770 the channel the message is destined to by checking the destination
1771 ID from the SILC Packet header which tells the destination channel.
1772 The original sender of the packet is also determined by checking
1773 the source ID from the header which tells the client which sent
1776 This packet use generic Message Payload as Channel Message Payload.
1777 See section 2.3.2.5 for generic Message Payload.
1781 2.3.10 Channel Key Payload
1783 All traffic in channels are protected by channel specific keys.
1784 Channel Key Payload is used to distribute channel keys to all
1785 clients on the particular channel. Channel keys are sent when
1786 the channel is created, when new user joins to the channel and
1787 whenever a user has left a channel. Server creates the new
1788 channel key and distributes it to the clients by encrypting this
1789 payload with the session key shared between the server and
1790 the client. After that, client MUST start using the key received
1791 in this payload to protect the traffic on the channel.
1793 The client which is joining to the channel receives its key in the
1794 SILC_COMMAND_JOIN command reply message thus it is not necessary to
1795 send this payload to the entity which sent the SILC_COMMAND_JOIN
1798 Channel keys are cell specific thus every router in the cell have
1799 to create a channel key and distribute it if any client in the
1800 cell has joined to a channel. Channel traffic between cell's
1801 are not encrypted using channel keys, they are encrypted using
1802 normal session keys between two routers. Inside a cell, all
1803 channel traffic is encrypted with the specified channel key.
1804 Channel key SHOULD expire periodically, say, in one hour, in
1805 which case new channel key is created and distributed.
1807 Note that, this packet is not used if SILC_CMODE_PRIVKEY mode is set
1808 on channel. This means that channel uses channel private keys which
1809 are not server generated. For this reason server cannot send this
1810 packet as it does not know the key.
1812 The payload may only be sent with SILC_PACKET_CHANNEL_KEY packet.
1813 It MUST NOT be sent in any other packet type. The following diagram
1814 represents the Channel Key Payload.
1825 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
1826 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1827 | Channel ID Length | |
1828 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1832 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1833 | Cipher Name Length | |
1834 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1838 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1839 | Channel Key Length | |
1840 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1844 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1848 Figure 15: Channel Key Payload
1853 o Channel ID Length (2 bytes) - Indicates the length of the
1854 Channel ID field in the payload, not including any other
1857 o Channel ID (variable length) - The Channel ID of the
1860 o Cipher Name Length (2 bytes) - Indicates the length of the
1861 Cipher name field in the payload, not including any other
1864 o Cipher Name (variable length) - Name of the cipher used
1865 in the protection of channel traffic. This name is
1866 initially decided by the creator of the channel but it
1867 may change during the life time of the channel as well.
1869 o Channel Key Length (2 bytes) - Indicates the length of the
1870 Channel Key field in the payload, not including any other
1873 o Channel Key (variable length) - The actual channel key
1879 2.3.11 Private Message Payload
1881 Private Message Payload is used to send private message between
1882 two clients. The messages are sent only to the specified user
1883 and no other user inside SILC network is able to see the message.
1885 The message can be protected by the session key established by the
1886 SILC Key Exchange Protocol. However, it is also possible to agree
1887 to use a private key to protect just the private messages. It is
1888 for example possible to perform Key Agreement between two clients.
1889 See section 2.3.20 Key Agreement Payload how to perform key
1890 agreement. See also section 2.3.12 Private Message Key Payload
1891 for another way of using private keys with private messages. See
1892 [SILC1] section 4.6 for detailed description for private message
1893 key generation procedure.
1895 If normal session key is used to protect the message, every server
1896 between the sender client and the receiving client MUST decrypt the
1897 packet and always re-encrypt it with the session key of the next
1898 receiver of the packet. See section Client To Client in [SILC1].
1900 When the private message key is used, and the Private Message Key
1901 flag was set in the SILC Packet header no server or router en route
1902 is able to decrypt or re-encrypt the packet. In this case only the
1903 SILC Packet header is processed by the servers and routers en route.
1904 Section Client To Client in [SILC1] gives example of this scheme.
1906 This packet use generic Message Payload as Private Message Payload.
1907 See section 2.3.2.5 for generic Message Payload.
1911 2.3.12 Private Message Key Payload
1913 This payload is OPTIONAL and can be used to send private message
1914 key between two clients in the network. The packet is secured with
1915 normal session keys. By default private messages are encrypted
1916 with session keys, and with this payload it is possible to set
1917 private key for private message encryption between two clients.
1919 The receiver of this payload SHOULD verify for example from user
1920 whether user want to receive private message key. Note that there
1921 are other, more secure ways of exchanging private message keys in
1922 the SILC network. Instead of sending this payload it is possible to
1923 negotiate the private message key with SKE protocol using the Key
1924 Agreement payload directly peer to peer, see section 2.3.20.
1926 This payload may only be sent by client to another client. Server
1927 MUST NOT send this payload. After sending this payload the sender of
1928 private messages must set the Private Message Key flag into SILC Packet
1931 The payload may only be sent with SILC_PACKET_PRIVATE_MESSAGE_KEY
1932 packet. It MUST NOT be sent in any other packet type. The following
1933 diagram represents the Private Message Key Payload.
1941 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
1942 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1943 | Private Message Key Length | |
1944 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1946 ~ Private Message Key ~
1948 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1949 | Cipher Name Length | |
1950 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1954 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1955 | HMAC Name Length | |
1956 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1960 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1964 Figure 16: Private Message Key Payload
1969 o Private Message Key Length (2 bytes) - Indicates the length
1970 of the Private Message Key field in the payload, not including
1973 o Private Message Key (variable length) - The actual private
1974 message key material.
1976 o Cipher Name Length (2 bytes) - Indicates the length of the
1977 Cipher Name field in the payload, not including any other
1980 o Cipher Name (variable length) - Name of the cipher to use
1981 in the private message encryption. If this field does not
1982 exist then the default cipher of the SILC protocol is used.
1983 See the [SILC1] for defined ciphers.
1985 o HMAC Name Length (2 bytes) - Indicates the length of the
1986 HMAC Name field in the payload, not including any other
1989 o HMAC Name (variable length) - Name of the HMAC to use
1990 in the private message MAC computation. If this field does
1991 not exist then the default HMAC of the SILC protocol is used.
1992 See the [SILC1] for defined HMACs.
1997 2.3.13 Command Payload
1999 Command Payload is used to send SILC commands from client to server.
2000 Also server MAY send commands to other servers. The following diagram
2001 represents the Command Payload.
2007 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
2008 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2009 | Payload Length | SILC Command | Arguments Num |
2010 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2011 | Command Identifier |
2012 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2016 Figure 17: Command Payload
2020 o Payload Length (2 bytes) - Length of the entire command
2021 payload including any command argument payloads associated
2024 o SILC Command (1 byte) - Indicates the SILC command. This MUST
2025 be set to non-zero value. If zero (0) value is found in this
2026 field the packet MUST be discarded.
2028 o Arguments Num (1 byte) - Indicates the number of arguments
2029 associated with the command. If there are no arguments this
2030 field is set to zero (0). The arguments MUST follow the
2031 Command Payload. See section 2.3.2.2 for definition of the
2034 o Command Identifier (2 bytes) - Identifies this command at the
2035 sender's end. The entity which replies to this command MUST
2036 set the value found from this field into the Command Payload
2037 used to send the reply to the sender. This way the sender
2038 can identify which command reply belongs to which originally
2039 sent command. What this field includes is implementation
2040 issue but it is RECOMMENDED that wrapping counter value is
2044 See [SILC4] for detailed description of different SILC commands,
2045 their arguments and their reply messages.
2049 2.3.14 Command Reply Payload
2051 Command Reply Payload is used to send replies to the commands. The
2052 Command Reply Payload is identical to the Command Payload thus see
2053 the 2.3.13 section for the payload specification.
2055 The entity which sends the reply packet MUST set the Command Identifier
2056 field in the reply packet's Command Payload to the value it received
2057 in the original command packet.
2059 See SILC Commands in [SILC4] for detailed description of different
2060 SILC commands, their arguments and their reply messages.
2064 2.3.15 Connection Auth Request Payload
2066 Client MAY send this payload to server to request the authentication
2067 method that must be used in authentication protocol. If client knows
2068 this information beforehand this payload is not necessary to be sent.
2069 Server performing authentication with another server MAY also send
2070 this payload to request the authentication method. If the connecting
2071 server already knows this information this payload is not necessary
2074 Server receiving this request SHOULD reply with same payload sending
2075 the mandatory authentication method. Algorithms that may be required
2076 to be used by the authentication method are the ones already
2077 established by the SILC Key Exchange protocol. See section Key
2078 Exchange Start Payload in [SILC3] for detailed information.
2080 The payload may only be sent with SILC_PACKET_CONNECTION_AUTH_REQUEST
2081 packet. It MUST NOT be sent in any other packet type. The following
2082 diagram represents the Connection Auth Request Payload.
2090 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
2091 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2092 | Connection Type | Authentication Method |
2093 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2097 Figure 18: Connection Auth Request Payload
2101 o Connection Type (2 bytes) - Indicates the type of the
2102 connection. The following connection types are defined:
2109 If any other type is found in this field the packet MUST be
2110 discarded and the authentication MUST be failed.
2112 o Authentication Method (2 bytes) - Indicates the authentication
2113 method to be used in the authentication protocol. The following
2114 authentication methods are defined:
2117 1 password (mandatory)
2118 2 public key (mandatory)
2120 If any other type is found in this field the packet MUST be
2121 discarded and the authentication MUST be failed. If this
2122 payload is sent as request to receive the mandatory
2123 authentication method this field MUST be set to zero (0),
2124 indicating that receiver should send the mandatory
2125 authentication method. The receiver sending this payload
2126 to the requesting party, MAY also set this field to zero (0)
2127 to indicate that authentication is not required. In this
2128 case authentication protocol still MUST be started but
2129 server is most likely to respond with SILC_PACKET_SUCCESS
2135 2.3.16 New ID Payload
2137 New ID Payload is a multipurpose payload. It is used to send newly
2138 created ID's from clients and servers. When client connects to server
2139 and registers itself to the server by sending SILC_PACKET_NEW_CLIENT
2140 packet, server replies with this packet by sending the created ID for
2141 the client. Server always creates the ID for the client.
2143 This payload is also used when server tells its router that new client
2144 has registered to the SILC network. In this case the server sends
2145 the Client ID of the client to the router. Similarly when router
2146 distributes information to other routers about the client in the SILC
2147 network this payload is used.
2149 Also, when server connects to router, router use this payload to inform
2150 other routers about new server in the SILC network. However, every
2151 server (or router) creates their own ID's thus the ID distributed by
2152 this payload is not created by the distributor in this case. Servers
2153 create their own ID's. Server registers itself to the network by
2154 sending SILC_PACKET_NEW_SERVER to the router it connected to. The case
2155 is same when router connects to another router.
2157 This payload MUST NOT be used to send information about new channels.
2158 New channels are always distributed by sending the dedicated
2159 SILC_PACKET_NEW_CHANNEL packet. Client MUST NOT send this payload.
2160 Both client and server (and router) MAY receive this payload.
2162 The packet use generic ID Payload as New ID Payload. See section
2163 2.3.2.1 for generic ID Payload.
2167 2.3.17 New Client Payload
2169 When client is connected to the server, keys has been exchanged and
2170 connection has been authenticated, client MUST register itself to the
2171 server. Client's first packet after key exchange and authentication
2172 protocols MUST be SILC_PACKET_NEW_CLIENT. This payload tells server all
2173 the relevant information about the connected user. Server creates a new
2174 client ID for the client when received this payload and sends it to the
2175 client in New ID Payload.
2177 This payload sends username and real name of the user on the remote host
2178 which is connected to the SILC server with SILC client. The server
2179 creates the client ID according the information sent in this payload.
2180 The nickname of the user becomes the nickname sent in this payload.
2182 The payload may only be sent with SILC_PACKET_NEW_CLIENT packet. It
2183 MUST NOT be sent in any other packet type. The following diagram
2184 represents the New Client Payload.
2195 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
2196 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2197 | Username Length | |
2198 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2202 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2203 | Real Name Length | |
2204 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2208 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2212 Figure 19: New Client Payload
2216 o Username Length (2 bytes) - Length of the Username field.
2218 o Username (variable length) - The username of the user on
2219 the host where connecting to the SILC server.
2221 o Real Name Length (2 bytes) - Length of the Real Name field.
2223 o Real Name (variable length) - The real name of the user
2224 on the host where connecting to the SILC server.
2229 2.3.18 New Server Payload
2231 This payload is sent by server when it has completed successfully both
2232 key exchange and connection authentication protocols. The server
2233 MUST register itself to the SILC Network by sending this payload.
2234 The first packet after these key exchange and authentication protocols
2235 is SILC_PACKET_NEW_SERVER packet. The payload includes the Server ID
2236 of the server that it has created by itself. It also includes a
2237 name of the server that is associated to the Server ID.
2239 The payload may only be sent with SILC_PACKET_NEW_SERVER packet. It
2240 MUST NOT be sent in any other packet type. The following diagram
2241 represents the New Server Payload.
2250 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
2251 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2252 | Server ID Length | |
2253 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2258 | Server Name Length | |
2259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2263 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2267 Figure 20: New Server Payload
2271 o Server ID Length (2 bytes) - Length of the Server ID Data
2274 o Server ID Data (variable length) - The encoded Server ID
2277 o Server Name Length (2 bytes) - Length of the server name
2280 o Server Name (variable length) - The server name string.
2285 2.3.19 New Channel Payload
2287 Information about newly created channel is broadcasted to all routers
2288 in the SILC network by sending this packet payload. Channels are
2289 created by router of the cell. Server never creates channels unless
2290 it is a standalone server and it does not have router connection,
2291 in this case server acts as router. Normal server send JOIN command
2292 to the router (after it has received JOIN command from client) which
2293 then processes the command and creates the channel. Client MUST NOT
2294 send this packet. Server MAY send this packet to a router when it is
2295 announcing its existing channels to the router after it has connected
2298 The packet use generic Channel Payload as New Channel Payload. See
2299 section 2.3.2.3 for generic Channel Payload. The Mode Mask field in the
2300 Channel Payload is the mode of the channel.
2304 2.3.20 Key Agreement Payload
2306 This payload is used by clients to request key negotiation between
2307 another client in the SILC Network. The key agreement protocol used
2308 is the SKE protocol. The result of the protocol, the secret key
2309 material, can be used for example as private message key between the
2310 two clients. This significantly adds security as the clients agree
2311 about the key without any server interaction. The protocol is executed
2312 peer to peer. The server and router MUST NOT send this payload.
2314 The sender MAY tell the receiver of this payload the hostname and the
2315 port where the SKE protocol is running in the sender's end. The
2316 receiver MAY then initiate the SKE negotiation with the sender. The
2317 sender MAY also optionally not to include the hostname and the port
2318 of its SKE protocol. In this case the receiver MAY reply to the
2319 request by sending the same payload filled with the receiver's hostname
2320 and the port where the SKE protocol is running. The sender MAY then
2321 initiate the SKE negotiation with the receiver.
2323 This payload may be sent with SILC_PACKET_KEY_AGREEMENT and
2324 SILC_PACKET_FTP packet types. It MUST NOT be sent in any other packet
2325 types. The following diagram represents the Key Agreement Payload.
2331 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
2332 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2333 | Hostname Length | |
2334 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2338 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2340 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2344 Figure 21: Key Agreement Payload
2348 o Hostname Length (2 bytes) - Indicates the length of the
2351 o Hostname (variable length) - The hostname or IP address where
2352 the SKE protocol is running. The sender MAY fill this field
2353 when sending the payload. If the receiver sends this payload
2354 as reply to the request it MUST fill this field.
2356 o Port (4 bytes) - The port where the SKE protocol is bound.
2357 The sender MAY fill this field when sending the payload. If
2358 the receiver sends this payload as reply to the request it
2359 MUST fill this field. This is a 32 bit MSB first order value.
2363 After the key material has been received from the SKE protocol it is
2364 processed as the [SILC3] describes. If the key material is used as
2365 channel private key then the Sending Encryption Key, as defined in
2366 [SILC3] is used as the channel private key. Other key material must
2367 be discarded. The [SILC1] in section 4.6 defines the way to use the
2368 key material if it is intended to be used as private message keys.
2369 Any other use for the key material is undefined.
2373 2.3.21 Resume Router Payload
2375 See the [SILC1] for Resume Router protocol where this payload is
2376 used. The payload may only be sent with SILC_PACKET_RESUME_ROUTER
2377 packet. It MUST NOT be sent in any other packet type. The following
2378 diagram represents the Resume Router Payload.
2384 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
2385 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2386 | Type | Session ID |
2387 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2391 Figure 22: Resume Router Payload
2395 o Type (1 byte) - Indicates the type of the backup resume
2396 protocol packet. The type values are defined in [SILC1].
2398 o Session ID (1 bytes) - Indicates the session ID for the
2399 backup resume protocol. The sender of the packet sets this
2400 value and the receiver MUST set the same value in subsequent
2406 2.3.22 File Transfer Payload
2408 File Transfer Payload is used to perform file transfer protocol between
2409 two entities in the network. The actual file transfer protocol is always
2410 encapsulated inside the SILC Packet. The actual data stream is also sent
2411 peer to peer outside SILC network.
2413 When an entity, usually a client wishes to perform file transfer protocol
2414 with another client in the network, they perform Key Agreement protocol
2415 as described in the section 2.3.20 Key Agreement Payload and in [SILC3],
2416 inside File Transfer Payload. After the Key Agreement protocol has been
2417 performed the subsequent packets in the data stream will be protected
2418 using the new key material. The actual file transfer protocol is also
2419 initialized in this stage. All file transfer protocol packets are always
2420 encapsulated in the File Transfer Payload and protected with the
2421 negotiated key material.
2423 The payload may only be sent with SILC_PACKET_FTP packet. It MUST NOT
2424 be sent in any other packet type. The following diagram represents the
2425 File Transfer Payload.
2431 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
2432 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2438 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2442 Figure 23: File Transfer Payload
2446 o Type (1 byte) - Indicates the type of the file transfer
2447 protocol. The following file transfer protocols has been
2450 1 Secure File Transfer Protocol (SFTP) (mandatory)
2452 If zero (0) value or any unsupported file transfer protocol
2453 type is found in this field the packet MUST be discarded.
2454 The currently mandatory file transfer protocol is SFTP.
2455 The SFTP protocol is defined in [SFTP].
2457 o Data (variable length) - Arbitrary file transfer data. The
2458 contents and encoding of this field is dependent of the usage
2459 of this payload and the type of the file transfer protocol.
2460 When this payload is used to perform the Key Agreement
2461 protocol, this field include the Key Agreement Payload,
2462 as defined in the section 2.3.20 Key Agreement Payload.
2463 When this payload is used to send the actual file transfer
2464 protocol data, the encoding is defined in the corresponding
2465 file transfer protocol.
2470 2.3.23 Resume Client Payload
2472 This payload is used by client to resume its detached session in the
2473 SILC Network. A client is able to detach itself from the network by
2474 sending SILC_COMMAND_DETACH command to its server. The network
2475 connection to the client is lost but the client remains as valid
2476 client in the network. The client is able to resume the session back
2477 by sending this packet and including the old Client ID, and an
2478 Authentication Payload [SILC1] which the server use to verify with
2479 the detached client's public key. This also implies that the
2480 mandatory authentication method is public key authentication.
2482 Server or router that receives this from the client also sends this,
2483 without the Authentication Payload, to routers in the network so that
2484 they know the detached client has resumed. Refer to the [SILC1] for
2485 detailed description how the detaching and resuming procedure is
2488 The payload may only be sent with SILC_PACKET_RESUME CLIENT packet. It
2489 MUST NOT be sent in any other packet type. The following diagram
2490 represents the Resume Client Payload.
2495 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
2496 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2497 | Client ID Length | |
2498 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2502 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2504 ~ Authentication Payload ~
2506 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2510 Figure 24: Resume Client Payload
2514 o Client ID Length (1 byte) - The length of the Client ID
2515 field not including any other field.
2517 o Client ID (variable length) - The detached client's Client
2518 ID. The client that sends this payload must know the Client
2521 o Authentication Payload (variable length) - The authentication
2522 payload that the server will verify with the detached client's
2523 public key. If the server doesn't know the public key, it must
2524 retrieve it for example with SILC_COMMAND_GETKEY command.
2532 ID's are used in the SILC network to associate different entities.
2533 The following ID's has been defined to be used in the SILC network.
2538 This is used when other ID type is available at the time.
2542 Server ID to associate servers. See the format of
2547 Client ID to associate clients. See the format of
2552 Channel ID to associate channels. See the format of
2556 When encoding different IDs into the ID Payload, all fields are always
2557 in MSB first order. The IP address, port, and/or the random number
2558 are encoded in the MSB first order.
2562 2.5 Packet Encryption And Decryption
2564 SILC packets are encrypted almost entirely. Only the MAC at the end
2565 of the packet is never encrypted. The SILC Packet header is the first
2566 part of a packet to be encrypted and it is always encrypted with the
2567 key of the next receiver of the packet. The data payload area of the
2568 packet is always entirely encrypted and it is usually encrypted with
2569 the next receiver's key. However, there are some special packet types
2570 and packet payloads that require special encryption process. These
2571 special cases are described in the next sections. First is described
2572 the normal packet encryption process.
2577 2.5.1 Normal Packet Encryption And Decryption
2579 Normal SILC packets are encrypted with the session key of the next
2580 receiver of the packet. The entire SILC Packet header and the packet
2581 data payload is is encrypted with the same key. Padding of the packet
2582 is also encrypted always with the session key, also in special cases.
2583 Computed MAC of the packet MUST NOT be encrypted.
2585 Decryption process in these cases are straightforward. The receiver
2586 of the packet MUST first decrypt the SILC Packet header, or some parts
2587 of it, usually first 16 bytes of it. Then the receiver checks the
2588 packet type from the decrypted part of the header and can determine
2589 how the rest of the packet must be decrypted. If the packet type is
2590 any of the special cases described in the following sections the packet
2591 decryption is special. If the packet type is not among those special
2592 packet types rest of the packet can be decrypted with the same key.
2593 At this point the receiver is also able to determine the length of the
2596 With out a doubt, this sort of decryption processing causes some
2597 overhead to packet decryption, but never the less, is required.
2599 The MAC of the packet is also verified at this point. The MAC is
2600 computed from the ciphertext of the packet so it can be verified
2601 at this stage. The length of the packet need to be known to be able
2602 to verify the MAC from the ciphertext so the first 16 bytes need to
2603 be decrypted to determine the packet length. However, the MAC MUST
2604 be verified from the entire ciphertext.
2608 2.5.2 Channel Message Encryption And Decryption
2610 Channel Messages (Channel Message Payload) are always encrypted with
2611 the channel specific key. However, the SILC Packet header is not
2612 encrypted with that key. As in normal case, the header is encrypted
2613 with the key of the next receiver of the packet. Note that, in this
2614 case the encrypted data area is not touched at all; it MUST NOT be
2615 re-encrypted with the session key.
2617 Receiver of a channel message, who ever that is, is REQUIRED to decrypt
2618 the SILC Packet header to be able to recognize the packet to be as
2619 channel message. This is same procedure as for normal SILC packets.
2620 As the receiver founds the packet to be channel message, rest of the
2621 packet processing is special. Rest of the SILC Packet header is
2622 decrypted with the same session key along with the padding of the
2623 packet. After that the packet is protected with the channel specific
2624 key and thus can be decrypted only if the receiver is the client on
2625 the channel. See section 2.7 Packet Padding Generation for more
2626 information about padding on special packets.
2628 If the receiver of the channel message is router which is routing the
2629 message to another router then it MUST decrypt the Channel Message
2630 payload too. Between routers (that is, between cells) channel messages
2631 are protected with session keys shared between the routers. This
2632 causes another special packet processing for channel messages. If
2633 the channel message is received from another router then the entire
2634 packet, including Channel Message payload, MUST be encrypted with the
2635 session key shared between the routers. In this case the packet
2636 decryption process is as with normal SILC packets. Hence, if the
2637 router is sending channel message to another router the Channel
2638 Message payload MUST have been decrypted and MUST be re-encrypted
2639 with the session key shared between the another router. In this
2640 case the packet encryption is as with any normal SILC packet.
2642 It must be noted that this is only when the channel messages are sent
2643 from router to another router. In all other cases the channel
2644 message encryption and decryption is as described before. This
2645 different processing of channel messages with router to router
2646 connection is because channel keys are cell specific. All cells have
2647 their own channel keys thus the channel message traveling from one
2648 cell to another MUST be protected as it would be any normal SILC
2651 If the SILC_CMODE_PRIVKEY channel mode has been set for the channel
2652 then the router cannot decrypt the packet as it does not know the
2653 private key. In this case the entire packet MUST be encrypted with
2654 the session key and sent to the router. The router receiving the
2655 packet MUST check the channel mode and decrypt the packet accordingly.
2659 2.5.3 Private Message Encryption And Decryption
2661 By default, private message in SILC are protected by session keys.
2662 In this case the private message encryption and decryption process is
2663 equivalent to normal packet encryption and decryption.
2665 However, private messages MAY be protected with private message key
2666 which causes the packet to be special packet. The procedure in this
2667 case is very much alike to channel packets. The actual private message
2668 is encrypted with the private message key and other parts of the
2669 packet is encrypted with the session key. See 2.7 Packet Padding
2670 Generation for more information about padding on special packets.
2672 The difference from channel message processing is that server or router
2673 en route never decrypts the actual private message, as it does not
2674 have the key to do that. Thus, when sending packets between router
2675 the processing is same as in any other case as well; the packet's header
2676 and padding is protected by the session key and the data area is not
2677 touched and is not re-encrypted.
2679 The true receiver of the private message is able to decrypt the private
2680 message as it shares the key with the sender of the message.
2684 2.6 Packet MAC Generation
2686 Data integrity of a packet is protected by including a message
2687 authentication code (MAC) at the end of the packet. The MAC is computed
2688 from shared secret MAC key, that is established by the SILC Key Exchange
2689 protocol, from packet sequence number, and from the encrypted packet
2690 data. The MAC is always computed after packet is encrypted. This is
2691 so called Encrypt-Then-MAC order; packet is first encrypted, then MAC
2692 is computed from the encrypted data.
2694 The MAC is computed from entire packet. Every bit of data in the packet,
2695 including SILC Packet Header is used in the MAC computing. This way
2696 the entire packet becomes authenticated.
2698 Hence, packet's MAC generation is as follows:
2700 mac = MAC(key, sequence number | Encrypted SILC packet)
2702 The MAC key is negotiated during the SKE protocol. The sequence number
2703 is a 32 bit MSB first value starting from zero for first packet and
2704 increasing for subsequent packets, finally wrapping after 2^32 packets.
2705 The value is never reset, not even after rekey has been performed.
2706 However, rekey MUST be performed before the sequence number wraps
2707 and repeats from zero. Note that the sequence number is incremented only
2708 when MAC is computed for a packet. If packet is not encrypted and MAC is
2709 not computed then the sequence number is not incremented. Hence, the
2710 sequence number is zero for the very first encrypted packet.
2712 See [SILC1] for defined and allowed MAC algorithms.
2716 2.7 Packet Padding Generation
2718 Padding is needed in the packet because the packet is encrypted. It
2719 always MUST be multiple by eight (8) or multiple by the block size
2720 of the cipher, which ever is larger. The padding is always encrypted.
2722 For normal packets the padding is added after the SILC Packet Header
2723 and between the Data Payload area. The padding for normal packets
2724 may be calculated as follows:
2727 padding_length = 16 - (packet_length mod block_size)
2728 if (padding_length < 8)
2729 padding_length += block_size
2732 The `block_size' is the block size of the cipher. The maximum padding
2733 length is 128 bytes, and minimum is 8 bytes. For example, packets that
2734 include a passphrase or a password for authentication purposes SHOULD
2735 pad the packet up to the maximum padding length. The maximum padding
2736 is calculated as follows:
2739 padding_length = 128 - (packet_length mod block_size)
2742 For special packets the padding calculation is different as special
2743 packets may be encrypted differently. In these cases the encrypted
2744 data area MUST already be multiple by the block size thus in this case
2745 the padding is calculated only for SILC Packet Header, not for any
2746 other area of the packet. The same algorithm works in this case as
2747 well, except that the `packet length' is now the SILC Packet Header
2750 The padding MUST be random data, preferably, generated by
2751 cryptographically strong random number generator for each packet
2756 2.8 Packet Compression
2758 SILC Packets MAY be compressed. In this case the data payload area
2759 is compressed and all other areas of the packet MUST remain as they
2760 are. After compression is performed for the data area, the length
2761 field of Packet Header MUST be set to the compressed length of the
2764 The compression MUST always be applied before encryption. When
2765 the packet is received and decrypted the data area MUST be decompressed.
2766 Note that the true sender of the packet MUST apply the compression and
2767 the true receiver of the packet MUST apply the decompression. Any
2768 server or router en route SHOULD NOT decompress the packet.
2774 The sender of the packet MUST assemble the SILC Packet Header with
2775 correct values. It MUST set the Source ID of the header as its own
2776 ID, unless it is forwarding the packet. It MUST also set the Destination
2777 ID of the header to the true destination. If the destination is client
2778 it will be Client ID, if it is server it will be Server ID and if it is
2779 channel it will be Channel ID.
2781 If the sender wants to compress the packet it MUST apply the
2782 compression now. Sender MUST also compute the padding as described
2783 in above sections. Then sender MUST encrypt the packet as has been
2784 described in above sections according whether the packet is normal
2785 packet or special packet. Then sender MUST compute the MAC of the
2786 packet. The computed MAC MUST NOT be encrypted.
2790 2.10 Packet Reception
2792 On packet reception the receiver MUST check that all fields in the
2793 SILC Packet Header are valid. It MUST check the flags of the
2794 header and act accordingly. It MUST also check the MAC of the packet
2795 and if it is to be failed the packet MUST be discarded. Also if the
2796 header of the packet includes any bad fields the packet MUST be
2799 See above sections on the decryption process of the received packet.
2801 The receiver MUST also check that the ID's in the header are valid
2802 ID's. Unsupported ID types or malformed ID's MUST cause packet
2803 rejection. The padding on the reception is always ignored.
2805 The receiver MUST also check the packet type and start parsing the
2806 packet according to the type. However, note the above sections on
2807 special packet types and their parsing.
2813 Routers are the primary entities in the SILC network that takes care
2814 of packet routing. However, normal servers routes packets as well, for
2815 example, when they are routing channel message to the local clients.
2816 Routing is quite simple as every packet tells the true origin and the
2817 true destination of the packet.
2819 It is still RECOMMENDED for routers that has several routing connections
2820 to create route cache for those destinations that has faster route than
2821 the router's primary route. This information is available for the router
2822 when other router connects to the router. The connecting party then
2823 sends all of its locally connected clients, servers and channels. These
2824 informations helps to create the route cache. Also, when new channels
2825 are created to a cell its information is broadcasted to all routers
2826 in the network. Channel ID's are based on router's ID thus it is easy
2827 to create route cache based on these informations. If faster route for
2828 destination does not exist in router's route cache the packet MUST be
2829 routed to the primary route (default route).
2831 However, there are some issues when routing channel messages to group
2832 of users. Routers are responsible of routing the channel message to
2833 other routers, local servers and local clients as well. Routers MUST
2834 send the channel message to only one router in the network, preferably
2835 to the shortest route to reach the channel users. The message can be
2836 routed into either upstream or downstream. After the message is sent
2837 to a router in the network it MUST NOT be sent to any other router in
2838 either same route or other route. The message MUST NOT be routed to
2839 the router it came from.
2841 When routing for example private messages they should be routed to the
2842 shortest route always to reach the destination client as fast as possible.
2844 For server which receives a packet to be routed to its locally connected
2845 client the server MUST check whether the particular packet type is
2846 allowed to be routed to the client. Not all packets may be sent by
2847 some odd entity to client that is indirectly connected to the sender.
2848 See section 2.3 SILC Packet Types and paragraph about indirectly connected
2849 entities and sending packets to them. The section mentions the packets
2850 that may be sent to indirectly connected entities. It is clear that
2851 server cannot send, for example, disconnect packet to client that is not
2852 directly connected to the server.
2854 Routers form a ring in the SILC network. However, routers may have other
2855 direct connections to other routers in the network too. This can cause
2856 interesting routing problems in the network. Since the network is a ring,
2857 the packets usually should be routed into clock-wise direction, or if it
2858 cannot be used then always counter clock-wise (primary route) direction.
2859 Problems may arise when a faster direct route exists and router is routing
2860 a channel message. Currently channel messages must be routed either
2861 in upstream or downstream, they cannot be routed to other direct routes.
2862 The SILC protocol should have a shortest path discovery protocol, and some
2863 existing routing protocol, that can handle a ring network with other
2864 direct routes inside the ring (so called hybrid ring-mesh topology),
2865 MAY be defined to be used with the SILC protocol. Additional
2866 specifications MAY be written on the subject to permeate this
2871 2.12 Packet Broadcasting
2873 SILC packets MAY be broadcasted in SILC network. However, only router
2874 server may send or receive broadcast packets. Client and normal server
2875 MUST NOT send broadcast packets and they MUST ignore broadcast packets
2876 if they receive them. Broadcast packets are sent by setting Broadcast
2877 flag to the SILC packet header.
2879 Broadcasting packets means that the packet is sent to all routers in
2880 the SILC network, except to the router that sent the packet. The router
2881 receiving broadcast packet MUST send the packet to its primary route.
2882 The fact that SILC routers may have several router connections can
2883 cause problems, such as race conditions inside the SILC network, if
2884 care is not taken when broadcasting packets. Router MUST NOT send
2885 the broadcast packet to any other route except to its primary route.
2887 If the primary route of the router is the original sender of the packet
2888 the packet MUST NOT be sent to the primary route. This may happen
2889 if router has several router connections and some other router uses
2890 the router as its primary route.
2892 Routers use broadcast packets to broadcast for example information
2893 about newly registered clients, servers, channels etc. so that all the
2894 routers may keep these informations up to date.
2898 3 Security Considerations
2900 Security is central to the design of this protocol, and these security
2901 considerations permeate the specification. Common security considerations
2902 such as keeping private keys truly private and using adequate lengths for
2903 symmetric and asymmetric keys must be followed in order to maintain the
2904 security of this protocol.
2910 [SILC1] Riikonen, P., "Secure Internet Live Conferencing (SILC),
2911 Protocol Specification", Internet Draft, May 2002.
2913 [SILC3] Riikonen, P., "SILC Key Exchange and Authentication
2914 Protocols", Internet Draft, May 2002.
2916 [SILC4] Riikonen, P., "SILC Commands", Internet Draft, May 2002.
2918 [IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
2921 [IRC-ARCH] Kalt, C., "Internet Relay Chat: Architecture", RFC 2810,
2924 [IRC-CHAN] Kalt, C., "Internet Relay Chat: Channel Management", RFC
2927 [IRC-CLIENT] Kalt, C., "Internet Relay Chat: Client Protocol", RFC
2930 [IRC-SERVER] Kalt, C., "Internet Relay Chat: Server Protocol", RFC
2933 [SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
2936 [PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
2939 [SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
2942 [PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
2943 Infrastructure, Certificate and CRL Profile", RFC 2459,
2946 [Schneier] Schneier, B., "Applied Cryptography Second Edition",
2947 John Wiley & Sons, New York, NY, 1996.
2949 [Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
2952 [OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
2953 RFC 2412, November 1998.
2955 [ISAKMP] Maughan D., et al, "Internet Security Association and
2956 Key Management Protocol (ISAKMP)", RFC 2408, November
2959 [IKE] Harkins D., and Carrel D., "The Internet Key Exchange
2960 (IKE)", RFC 2409, November 1998.
2962 [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
2963 Authentication", RFC 2104, February 1997.
2965 [PKCS1] Kalinski, B., and Staddon, J., "PKCS #1 RSA Cryptography
2966 Specifications, Version 2.0", RFC 2437, October 1998.
2968 [RFC2119] Bradner, S., "Key Words for use in RFCs to Indicate
2969 Requirement Levels", BCP 14, RFC 2119, March 1997.
2971 [SFTP] Ylonen T., and Lehtinen S., "Secure Shell File Transfer
2972 Protocol", Internet Draft, March 2001.
2974 [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO
2975 10646", RFC 2279, January 1998.
2983 Snellmaninkatu 34 A 15
2987 EMail: priikone@iki.fi
2991 6 Full Copyright Statement
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