8 .ds RF FORMFEED[Page %]
17 Network Working Group P. Riikonen
19 draft-riikonen-silc-pp-07.txt 30 June 2003
20 Expires: 30 December 2003
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
38 and may be updated, replaced, or obsoleted by other documents at any
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.
72 1 Introduction .................................................. 3
73 1.1 Requirements Terminology .................................. 4
74 2 SILC Packet Protocol .......................................... 4
75 2.1 SILC Packet ............................................... 4
76 2.2 SILC Packet Header ........................................ 5
77 2.3 SILC Packet Types ......................................... 8
78 2.3.1 SILC Packet Payloads ................................ 15
79 2.3.2 Generic payloads .................................... 16
80 2.3.2.1 ID Payload .................................. 16
81 2.3.2.2 Argument Payload ............................ 16
82 2.3.2.3 Argument List Payload ....................... 16
83 2.3.2.4 Channel Payload ............................. 17
84 2.3.2.5 Public Key Payload .......................... 18
85 2.3.2.6 Message Payload ............................. 19
86 2.3.3 Disconnect Payload .................................. 22
87 2.3.4 Success Payload ..................................... 23
88 2.3.5 Failure Payload ..................................... 23
89 2.3.6 Reject Payload ...................................... 24
90 2.3.7 Notify Payload ...................................... 25
91 2.3.8 Error Payload ....................................... 32
92 2.3.9 Channel Message Payload ............................. 33
93 2.3.10 Channel Key Payload ................................ 34
94 2.3.11 Private Message Payload ............................ 35
95 2.3.12 Private Message Key Payload ........................ 36
96 2.3.13 Command Payload .................................... 38
97 2.3.14 Command Reply Payload .............................. 39
98 2.3.15 Connection Auth Request Payload .................... 39
99 2.3.16 New ID Payload ..................................... 40
100 2.3.17 New Client Payload ................................. 41
101 2.3.18 New Server Payload ................................. 42
102 2.3.19 New Channel Payload ................................ 43
103 2.3.20 Key Agreement Payload .............................. 43
104 2.3.21 Resume Router Payload .............................. 44
105 2.3.22 File Transfer Payload .............................. 45
106 2.3.23 Resume Client Payload .............................. 47
107 2.4 SILC ID Types ............................................. 48
108 2.5 Packet Encryption And Decryption .......................... 49
109 2.5.1 Normal Packet Encryption And Decryption ............. 49
110 2.5.2 Channel Message Encryption And Decryption ........... 50
111 2.5.3 Private Message Encryption And Decryption ........... 51
112 2.6 Packet MAC Generation ..................................... 51
113 2.7 Packet Padding Generation ................................. 52
114 2.8 Packet Compression ........................................ 53
115 2.9 Packet Sending ............................................ 53
116 2.10 Packet Reception ......................................... 53
117 2.11 Packet Routing ........................................... 54
118 2.12 Packet Broadcasting ...................................... 55
119 3 Security Considerations ....................................... 56
120 4 References .................................................... 56
121 5 Author's Address .............................................. 57
122 6 Full Copyright Statement ...................................... 57
128 Figure 1: Typical SILC Packet
129 Figure 2: SILC Packet Header
131 Figure 4: Argument Payload
132 Figure 5: Argument List Payload
133 Figure 6: Channel Payload
134 Figure 7: Public Key Payload
135 Figure 8: Message Payload
136 Figure 9: Disconnect Payload
137 Figure 10: Success Payload
138 Figure 11: Failure Payload
139 Figure 12: Reject Payload
140 Figure 13: Notify Payload
141 Figure 14: Error Payload
142 Figure 15: Channel Key Payload
143 Figure 16: Private Message Key Payload
144 Figure 17: Command Payload
145 Figure 18: Connection Auth Request Payload
146 Figure 19: New Client Payload
147 Figure 20: New Server Payload
148 Figure 21: Key Agreement Payload
149 Figure 22: Resume Router Payload
150 Figure 23: File Transfer Payload
151 Figure 24: Resume Client Payload
157 This document describes a Packet Protocol used in the Secure Internet
158 Live Conferencing (SILC) protocol specified in the Secure Internet Live
159 Conferencing, Protocol Specification [SILC1]. This protocol describes
160 the packet types and packet payloads which defines the contents of the
161 packets. The protocol provides secure binary packet protocol that
162 assures that the contents of the packets are secured and authenticated.
163 The packet protocol is designed to be compact to avoid unnecessary
164 overhead as much as possible. This makes the SILC suitable also in
165 environment of low bandwidth requirements such as mobile networks. All
166 packet payloads can also be compressed to further reduce the size of
169 All packets in SILC network are always encrypted and their integrity
170 is assured by computed MACs. The protocol defines several packet types
171 and packet payloads. Each packet type usually has a specific packet
172 payload that actually defines the contents of the packet. Each packet
173 also includes a default SILC Packet Header that provides sufficient
174 information about the origin of the packet and destination of the
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.
202 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
203 | n bytes | 1 - n bytes | n bytes | n bytes
204 | SILC Header | Padding | Data Payload | MAC
205 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
209 Figure 1: Typical SILC Packet
212 SILC Header is always the first part of the packet and its purpose
213 is to provide information about the packet. It provides for example
214 the packet type, origin of the packet and the destination of the packet.
215 The header is variable in length. See the following section for
216 description of SILC Packet header. Packets without SILC header or
217 with malformed SILC header MUST be dropped.
219 Padding follows the packet header. The purpose of the padding is to
220 make the packet multiple by eight (8) or by the block size of the
221 cipher used in the encryption, which ever is larger. The maximum
222 length of padding is currently 128 bytes. The padding is always
223 encrypted. The padding is applied always, even if the packet is
224 not encrypted. See the section 2.7 Padding Generation for more
225 detailed information.
227 Data payload area follows padding and it is the actual data of the
228 packet. The packet data is the packet payloads defined in this
229 protocol. The data payload area is always encrypted.
231 The last part of SILC packet is the packet MAC that assures the
232 integrity of the packet. See the section 2.6 Packet MAC Generation
233 for more information. If compression is used the compression is
234 always applied before encryption.
236 All fields in all packet payloads are always in MSB (most significant
241 2.2 SILC Packet Header
243 The SILC packet header is applied to all SILC packets and it is
244 variable in length. The purpose of SILC Packet header is to provide
245 detailed information about the packet. The receiver of the packet
246 uses the packet header to parse the packet and gain other relevant
247 parameters of the packet.
249 The following diagram represents the SILC packet header.
254 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
255 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
256 | Payload Length | Flags | Packet Type |
257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
258 | Pad Length | RESERVED | Source ID Len | Dest ID Len |
259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
265 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
271 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
275 Figure 2: SILC Packet Header
279 o Payload Length (2 bytes) - Is the length of the packet
280 not including the padding of the packet.
282 o Flags (1 byte) - Indicates flags to be used in packet
283 processing. Several flags may be set by ORing the flags
286 The following flags are reserved for this field:
291 In this case the field is ignored.
294 Private Message Key 0x01
296 Indicates that the packet must include private
297 message that is encrypted using private key set by
298 client. Servers does not know anything about this
299 key and this causes that the private message is
300 not handled by the server at all, it is just
301 passed along. See section 2.5.3 Private Message
302 Encryption And Decryption for more information.
307 Indicates that the packet consists of list of
308 packet payloads indicated by the Packet Type field.
309 The payloads are added one after the other. Note that
310 there are packet types that must not be used as
311 list. Parsing of list packet is done by calculating
312 the length of each payload and parsing them one by
318 Marks the packet to be broadcasted. Client cannot
319 send broadcast packet and normal server cannot send
320 broadcast packet. Only router server may send broadcast
321 packet. The router receiving of packet with this flag
322 set MUST send (broadcast) the packet to its primary
323 route. If router has several router connections the
324 packet may be sent only to the primary route. See
325 section 2.12 Packet Broadcasting for description of
332 Marks that the payload of the packet is compressed.
333 The sender of the packet marks this flag when it
334 compresses the payload, and any server or router
335 en route to the recipient MUST NOT unset this flag.
336 See section 2.8 Packet Compression for description of
341 o Packet Type (1 byte) - Is the type of the packet. Receiver
342 uses this field to parse the packet. See section 2.3
343 SILC Packets for list of defined packet types.
345 o Pad Length (1 byte) - Indicates the length of the padding
346 applied after the SILC Packet header. Maximum length for
347 padding is 128 bytes.
349 o RESERVED (1 byte) - Reserved field and must include a
352 o Source ID Length (1 byte) - Indicates the length of the
353 Source ID field in the header, not including this or any
356 o Destination ID Length (1 byte) - Indicates the length of the
357 Destination ID field in the header, not including this or
360 o Src ID Type (1 byte) - Indicates the type of ID in the
361 Source ID field. See section 2.4 SILC ID Types for
364 o Source ID (variable length) - The actual source ID that
365 indicates which is the original sender of the packet.
367 o Dst ID Type (1 byte) - Indicates the type of ID in the
368 Destination ID field. See section 2.4 SILC ID Types for
371 o Destination ID (variable length) - The actual destination
372 ID that indicates which is the end receiver of the packet.
380 2.3 SILC Packet Types
382 SILC packet types defines the contents of the packet and it is used by
383 the receiver to parse the packet. The packet type is 8 bits, as a one
384 byte, in length. The range for the packet types are from 0 - 255,
385 where 0 is never sent and 255 is currently reserved for future
386 extensions and MUST NOT be defined to any other purpose. Every SILC
387 specification compliant implementation SHOULD support all of these packet
390 The below list of the SILC Packet types includes reference to the packet
391 payload as well. Packet payloads are the actual packet data area. Each
392 packet type defines packet payload which usually may only be sent with
393 the specific packet type.
395 Most of the packets are packets that must be destined directly to entity
396 that is connected to the sender. It is not allowed, for example, for a
397 router to send disconnect packet to client that is not directly connected
398 to the router. However, there are some special packet types that may
399 be destined to some entity that the sender does not have direct
400 connection with. These packets are for example private message packets,
401 channel message packets, command packets and some other packets that may
402 be broadcasted in the SILC network. If the packet is allowed to be sent
403 to indirectly connected entity it is defined separately in the packet
404 description below. Other packets MUST NOT be sent or accepted, if sent,
405 to indirectly connected entities.
407 Some packets MAY be sent as lists by adding the List flag to the Packet
408 Header and constructing multiple packet payloads one after the other.
409 When this is allowed it is separately defined below. Other packets
410 MUST NOT be sent as list and the List flag MUST NOT be set.
413 List of SILC Packet types are defined as follows.
418 This type is reserved and it is never sent.
421 1 SILC_PACKET_DISCONNECT
423 This packet is sent to disconnect the remote end. Reason of
424 the disconnection is sent inside the packet payload. Client
425 usually does not send this packet.
427 Payload of the packet: See section 2.3.3 Disconnect Payload
430 2 SILC_PACKET_SUCCESS
432 This packet is sent upon successful execution of some protocol.
433 The status of the success is sent in the packet.
435 Payload of the packet: See section 2.3.4 Success Payload
438 3 SILC_PACKET_FAILURE
440 This packet is sent upon failure of some protocol. The status
441 of the failure is sent in the packet.
443 Payload of the packet: See section 2.3.5 Failure Payload
448 This packet MAY be sent upon rejection of some protocol.
449 The status of the rejection is sent in the packet.
451 Payload of the packet: See section 2.3.6 Reject Payload
456 This packet is used to send notify message. The packet is
457 usually sent between server and client, but also between
458 server and router. Client MUST NOT send this packet. Server
459 MAY send this packet to channel as well when the packet is
460 distributed to all clients on the channel. This packet MAY
463 Payload of the packet: See section 2.3.7 Notify Payload.
469 This packet is sent when an error occurs. Server MAY
470 send this packet. Client MUST NOT send this packet. The
471 client MAY entirely ignore the packet, however, server is
472 most likely to take action anyway. This packet MAY be sent
473 to entity that is indirectly connected to the sender.
475 Payload of the packet: See section 2.3.8 Error Payload.
478 7 SILC_PACKET_CHANNEL_MESSAGE
480 This packet is used to send messages to channels. The packet
481 includes Channel ID of the channel and the actual message to
482 the channel. Messages sent to the channel are always protected
483 by channel specific keys. Channel Keys are distributed by
484 SILC_PACKET_CHANNEL_KEY packet. This packet MAY be sent to
485 entity that is indirectly connected to the sender.
487 Payload of the packet: See section 2.3.9 Channel Message
491 8 SILC_PACKET_CHANNEL_KEY
493 This packet is used to distribute new key for particular
494 channel. Each channel has their own independent keys that
495 is used to protect the traffic on the channel. Only server
496 may send this packet. This packet MAY be sent to entity
497 that is indirectly connected to the sender.
499 Payload of the packet: See section 2.3.10 Channel Key Payload
502 9 SILC_PACKET_PRIVATE_MESSAGE
504 This packet is used to send private messages from client
505 to another client. By default, private messages are protected
506 by session keys established by normal key exchange protocol.
507 However, it is possible to use specific key to protect private
508 messages. See [SILC1] for private message key generation.
509 This packet MAY be sent to entity that is indirectly connected
512 Payload of the packet: See section 2.3.11 Private Message
516 10 SILC_PACKET_PRIVATE_MESSAGE_KEY
518 This packet can be used to agree about a key to be used to
519 protect private messages between two clients. This packet
520 is sent inside the SILC network and protected with session
521 keys. There are other means of agreeing to use private message
522 keys as well, than sending this packet which may not be
523 desirable on all situations. See the [SILC1] for private
524 message key generation.
526 Payload of the packet: See section 2.3.12 Private Message
530 11 SILC_PACKET_COMMAND
532 This packet is used to send commands from client to server.
533 Server MAY send this packet to other servers as well. All
534 commands are listed in their own section SILC Command Types
535 in [SILC4]. The contents of this packet is command specific.
536 This packet MAY be sent to entity that is indirectly connected
539 Payload of the packet: See section 2.3.13 Command Payload
542 12 SILC_PACKET_COMMAND_REPLY
544 This packet is sent as reply to the SILC_PACKET_COMMAND packet.
545 The contents of this packet is command specific. This packet
546 MAY be sent to entity that is indirectly connected to the
549 Payload of the packet: See section 2.3.14 Command Reply
550 Payload and section 2.3.13 Command
556 13 SILC_PACKET_KEY_EXCHANGE
558 This packet is used to start SILC Key Exchange Protocol,
559 described in detail in [SILC3].
561 Payload of the packet: Payload of this packet is described
562 in the section SILC Key Exchange
563 Protocol and its sub sections in
567 14 SILC_PACKET_KEY_EXCHANGE_1
569 This packet is used as part of the SILC Key Exchange Protocol.
571 Payload of the packet: Payload of this packet is described
572 in the section SILC Key Exchange
573 Protocol and its sub sections in
577 15 SILC_PACKET_KEY_EXCHANGE_2
579 This packet is used as part of the SILC Key Exchange Protocol.
581 Payload of the packet: Payload of this packet is described
582 in the section SILC Key Exchange
583 Protocol and its sub sections in
587 16 SILC_PACKET_CONNECTION_AUTH_REQUEST
589 This packet is used to request an authentication method to
590 be used in the SILC Connection Authentication Protocol. If
591 initiator of the protocol does not know the mandatory
592 authentication method this packet MAY be used to determine it.
593 The party receiving this payload SHOULD respond with the same
594 packet including the mandatory authentication method.
596 Payload of the packet: See section 2.3.15 Connection Auth
602 17 SILC_PACKET_CONNECTION_AUTH
604 This packet is used to start and perform the SILC Connection
605 Authentication Protocol. This protocol is used to authenticate
606 the connecting party. The protocol is described in detail in
609 Payload of the packet: Payload of this packet is described
610 in the section SILC Authentication
611 Protocol and it sub sections in [SILC].
614 18 SILC_PACKET_NEW_ID
616 This packet is used to distribute new IDs from server to
617 router and from router to all other routers in SILC network.
618 This is used when for example new client is registered to
619 SILC network. The newly created IDs of these operations are
620 distributed by this packet. Only server may send this packet,
621 however, client MUST be able to receive this packet. This
622 packet MAY be sent to entity that is indirectly connected
623 to the sender. This packet MAY be sent as list.
625 Payload of the packet: See section 2.3.16 New ID Payload
628 19 SILC_PACKET_NEW_CLIENT
630 This packet is used by client to register itself to the
631 SILC network. This is sent after key exchange and
632 authentication protocols has been completed. Client sends
633 various information about itself in this packet.
635 Payload of the packet: See section 2.3.17 New Client Payload
638 20 SILC_PACKET_NEW_SERVER
640 This packet is used by server to register itself to the
641 SILC network. This is sent after key exchange and
642 authentication protocols has been completed. Server sends
643 this to the router it connected to, or, if router was
644 connecting, to the connected router. Server sends its
645 Server ID and other information in this packet. The client
646 MUST NOT send or receive this packet.
648 Payload of the packet: See section 2.3.18 New Server Payload
651 21 SILC_PACKET_NEW_CHANNEL
653 This packet is used to notify routers about newly created
654 channel. Channels are always created by the router and it MUST
655 notify other routers about the created channel. Router sends
656 this packet to its primary route. Client MUST NOT send this
657 packet. This packet MAY be sent to entity that is indirectly
658 connected to the sender. This packet MAY be sent as list.
660 Payload of the packet: See section 2.3.19 New Channel Payload
665 This packet is used to indicate that re-key must be performed
666 for session keys. See section Session Key Regeneration in
667 [SILC1] for more information. This packet does not have
671 23 SILC_PACKET_REKEY_DONE
673 This packet is used to indicate that re-key is performed and
674 new keys must be used hereafter. This packet does not have a
678 24 SILC_PACKET_HEARTBEAT
680 This packet is used by clients, servers and routers to keep the
681 connection alive. It is RECOMMENDED that all servers implement
682 keepalive actions and perform it to both direction in a link.
683 This packet does not have a payload.
686 25 SILC_PACKET_KEY_AGREEMENT
688 This packet is used by clients to request key negotiation
689 between another client in the SILC network. If the negotiation
690 is started it is performed using the SKE protocol. The result of
691 the negotiation, the secret key material, can be used for
692 example as private message key. The server and router MUST NOT
695 Payload of the packet: See section 2.3.20 Key Agreement Payload
698 26 SILC_PACKET_RESUME_ROUTER
700 This packet is used during backup router protocol when the
701 original primary router of the cell comes back online and wishes
702 to resume the position as being the primary router of the cell.
704 Payload of the packet: See section 2.3.21 Resume Router Payload
709 This packet is used to perform an file transfer protocol in the
710 SILC session with some entity in the network. The packet is
711 multi purpose. The packet is used to tell other entity in the
712 network that the sender wishes to perform an file transfer
713 protocol. The packet is also used to actually tunnel the
714 file transfer protocol stream. The file transfer protocol
715 stream is always protected with the SILC binary packet protocol.
717 Payload of the packet: See section 2.3.22 File Transfer Payload
720 28 SILC_PACKET_RESUME_CLIENT
722 This packet is used to resume a client back to the network
723 after it has been detached. A client is able to detach from
724 the network but the client is still valid client in the network.
725 The client may then later resume its session back by sending
726 this packet to a server. Routers also use this packet to notify
727 other routers in the network that the detached client has resumed.
729 Payload of the packet: See section 2.3.23 Resume Client Payload
734 Currently undefined commands.
739 These packet types are reserved for private use and they will
740 not be defined by this document.
745 This type is reserved for future extensions and currently it
751 2.3.1 SILC Packet Payloads
753 All payloads resides in the main data area of the SILC packet. However
754 all payloads MUST be at the start of the data area after the SILC
755 packet header and padding. All fields in the packet payload are always
756 encrypted, as they reside in the data area of the packet which is
759 Payloads described in this section are common payloads that MUST be
760 accepted anytime during SILC session. Most of the payloads may only
761 be sent with specific packet type which is defined in the description
764 There are many other payloads in SILC as well. However, they are not
765 common in the sense that they could be sent at any time. These payloads
766 are not described in this section. These are payloads such as SILC
767 Key Exchange payloads and so on. These are described in [SILC1],
772 2.3.2 Generic payloads
774 This section describes generic payloads that are not associated to any
775 specific packet type. They can be used for example inside some other
782 This payload can be used to send an ID. ID's are variable in length
783 thus this payload provides a way to send variable length ID.
785 The following diagram represents the ID Payload.
790 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
791 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
792 | ID Type | ID Length |
793 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
797 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
805 o ID Type (2 bytes) - Indicates the type of the ID. See
806 section 2.4 SILC ID Types for list of defined ID types.
808 o ID Length (2 bytes) - Length of the ID Data area not
809 including the length of any other fields in the payload.
811 o ID Data (variable length) - The actual ID data. The encoding
812 of the ID data is defined in section 2.4 SILC ID Types.
817 2.3.2.2 Argument Payload
819 Argument Payload is used to set arguments for any packet payload that
820 need and support arguments, such as commands. Number of arguments
821 associated with a packet MUST be indicated by the packet payload which
822 need the arguments. Argument Payloads MUST always reside right after
823 the packet payload needing the arguments. Incorrect amount of argument
824 payloads MUST cause rejection of the packet.
826 The following diagram represents the Argument Payload.
831 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
832 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
833 | Payload Length | Argument Type | |
834 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
838 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
842 Figure 4: Argument Payload
846 o Payload Length (2 bytes) - Length of the Argument Data
847 field not including the length of any other field in the
850 o Argument Type (1 byte) - Indicates the type of the argument.
851 Every argument can have a specific type that MUST be defined
852 by the packet payload needing the argument. For example
853 every command specify a number for each argument that may be
854 associated with the command. By using this number the receiver
855 of the packet knows what type of argument this is. If there is
856 no specific argument type this field is set to zero (0) value.
858 o Argument Data (variable length) - Argument data.
863 2.3.2.3 Argument List Payload
865 Argument List Payload is a list of Argument Payloads appended one
866 after the other. The number of arguments is indicated in the
870 The following diagram represents the Argument List Payload.
875 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
876 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
878 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
880 ~ Argument Payloads ~
882 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
886 Figure 5: Argument List Payload
890 o Argument Nums (2 bytes) - Indicates the number of Argument
891 Payloads. If zero (0) value is found in this field no
892 arguments are present.
894 o Argument Payloads (variable length) - The Argument Payloads
895 appended one after the other. The payloads can be decoded
896 since the length of the payload is indicated in each of
897 the Argument Payload.
903 2.3.2.4 Channel Payload
905 Generic Channel Payload may be used to send information about a channel,
906 its name, the Channel ID and a mode.
908 The following diagram represents the Channel Payload.
914 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
915 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
916 | Channel Name Length | |
917 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
921 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
922 | Channel ID Length | |
923 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
927 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
929 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
933 Figure 6: New Channel Payload
937 o Channel Name Length (2 bytes) - Length of the channel name
940 o Channel Name (variable length) - The name of the channel.
942 o Channel ID Length (2 bytes) - Length of the Channel ID field.
944 o Channel ID (variable length) - The Channel ID.
946 o Mode Mask (4 bytes) - A mode. This can be the mode of the
947 channel but it can also be the mode of a client on the
948 channel. The contents of this field is dependent of the
949 usage of this payload. The usage is defined separately
950 when this payload is used. This is a 32 bit MSB first value.
955 2.3.2.5 Public Key Payload
957 Generic Public Key Payload may be used to send different type of
958 public keys and certificates.
960 The following diagram represents the Public Key Payload.
965 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
966 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
967 | Public Key Length | Public Key Type |
968 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
970 ~ Public Key (or certificate) ~
972 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
976 Figure 7: Public Key Payload
980 o Public Key Length (2 bytes) - The length of the Public Key
981 (or certificate) field, not including any other field.
983 o Public Key Type (2 bytes) - The public key (or certificate)
984 type. This field indicates the type of the public key in
985 the packet. See the [SILC3] for defined public key types.
987 o Public Key (or certificate) (variable length) - The
988 public key or certificate data.
993 2.3.2.6 Message Payload
995 Generic Message Payload can be used to send messages in SILC. It
996 is used to send channel messages and private messages.
998 The following diagram represents the Message Payload.
1000 (*) indicates that the field is not encrypted.
1005 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
1006 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1007 | Message Flags | Message Length |
1008 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1012 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1013 | Padding Length | |
1014 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1018 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1020 ~ Initial Vector * ~
1022 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1026 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1030 Figure 8: Message Payload
1034 o Message Flags (2 bytes) - Includes the Message Flags of the
1035 message. The flags can indicate a reason or a purpose for
1036 the message. The following Message Flags are defined:
1038 0x0000 SILC_MESSAGE_FLAG_NONE
1040 No specific flags set.
1042 0x0001 SILC_MESSAGE_FLAG_AUTOREPLY
1044 This message is an automatic reply to an earlier
1047 0x0002 SILC_MESSAGE_FLAG_NOREPLY
1049 There should not be reply messages to this
1052 0x0004 SILC_MESSAGE_FLAG_ACTION
1054 The sender is performing an action and the message
1055 is the indication of the action.
1057 0x0008 SILC_MESSAGE_FLAG_NOTICE
1059 The message is for example an informational notice
1062 0x0010 SILC_MESSAGE_FLAG_REQUEST
1064 This is a generic request flag to send request
1065 messages. A separate document should define any
1066 payloads associated to this flag.
1068 0x0020 SILC_MESSAGE_FLAG_SIGNED
1070 This flag indicates that the message is signed
1071 with sender's private key and thus can be verified
1072 by the receiver using the sender's public key. A
1073 separate document should define the detailed procedure
1074 of the signing process and any associated payloads
1077 0x0040 SILC_MESSAGE_FLAG_REPLY
1079 This is a generic reply flag to send a reply to
1080 previously received request. A separate document
1081 should define any payloads associated to this flag.
1083 0x0080 SILC_MESSAGE_FLAG_DATA
1085 This is a generic data flag, indicating that the
1086 message includes some data which can be interpreted
1087 in a specific way. Using this flag any kind of data
1088 can be delivered inside message payload. A separate
1089 document should define how this flag is interpreted
1090 and define any associated payloads.
1092 0x0100 SILC_MESSAGE_FLAG_UTF8
1094 This flag indicates that the message is UTF-8 encoded
1095 textual message. When sending text messages in SILC
1096 this flag SHOULD be used. When this flag is used the
1097 text sent as message MUST be UTF-8 encoded.
1099 0x0200 - 0x0800 RESERVED
1101 Reserved for future flags.
1103 0x1000 - 0x8000 PRIVATE RANGE
1105 Private range for free use.
1107 o Message Length (2 bytes) - Indicates the length of the
1108 Message Data field in the payload, not including any
1111 o Message Data (variable length) - The actual message data.
1113 o Padding Length (2 bytes) - Indicates the length of the
1114 Padding field in the payload, not including any other
1117 o Padding (variable length) - If this payload is used as
1118 channel messages, the padding MUST be applied because
1119 this payload is encrypted separately from other parts
1120 of the packet. If this payload is used as private
1121 messages, the padding is present only when the payload
1122 is encrypted with private message key. If encrypted
1123 with session keys this field MUST NOT be present and the
1124 Padding Length field includes a zero (0) value. The
1125 padding SHOULD be random data.
1127 o Initial Vector (variable length) - This field MUST be
1128 present when this payload is used as channel messages.
1129 The IV SHOULD be random data for each channel message.
1131 When encrypting private messages with session keys this
1132 field MUST NOT be present. For private messages this
1133 field is present only when encrypting with a static
1134 private message key (pre-shared key). If randomly
1135 generated key material is used this field MUST NOT be
1136 present. Also, If Key Agreement (SKE) was used to
1137 negotiate fresh key material for private message key
1138 this field MUST NOT be present. See the section 4.6
1139 in [SILC1] for more information about IVs when
1140 encrypting private messages.
1142 This field includes the initial vector used in message
1143 encryption. It need to be used in the packet decryption
1144 as well. Contents of this field depends on the encryption
1145 algorithm and encryption mode. This field is not encrypted,
1146 is not included in padding calculation and its length
1147 equals to cipher's block size. This field is authenticated
1150 o MAC (variable length) - The MAC computed from the
1151 Message Flags, Message Length, Message Data, Padding Length,
1152 Padding and Initial Vector fields in that order. The MAC
1153 is computed after the payload is encrypted. This is so
1154 called Encrypt-Then-MAC order; first encrypt, then compute
1155 MAC from ciphertext. The MAC protects the integrity of
1156 the Message Payload. Also, when used as channel messages
1157 it is possible to have multiple private channel keys set,
1158 and receiver can use the MAC to verify which of the keys
1159 must be used in decryption. This field is not encrypted.
1164 2.3.3 Disconnect Payload
1166 Disconnect payload is sent upon disconnection. Reason of the
1167 disconnection is sent to the disconnected party in the payload.
1169 The payload may only be sent with SILC_PACKET_DISCONNECT packet. It
1170 MUST NOT be sent in any other packet type. The following diagram
1171 represents the Disconnect Payload.
1177 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
1178 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1182 ~ Disconnect Message ~
1184 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1188 Figure 9: Disconnect Payload
1191 o Status (1 byte) - Indicates the Status Type, defined in [SILC3]
1192 for the reason of disconnection.
1194 o Disconnect Message (variable length) - Human readable UTF-8
1195 encoded string indicating reason of the disconnection. This
1196 field MAY be omitted.
1201 2.3.4 Success Payload
1203 Success payload is sent when some protocol execution is successfully
1204 completed. The payload is simple; indication of the success is sent.
1205 This may be any data, including binary or human readable data, and
1206 it is protocol dependent.
1211 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
1212 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1214 ~ Success Indication ~
1216 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1220 Figure 10: Success Payload
1224 o Success Indication (variable length) - Indication of
1225 the success. This may be for example some flag that
1226 indicates the protocol and the success status or human
1227 readable success message. The true length of this
1228 payload is available by calculating it from the SILC
1235 2.3.5 Failure Payload
1237 This is opposite of Success Payload. Indication of failure of
1238 some protocol is sent in the payload.
1249 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
1250 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1252 ~ Failure Indication ~
1254 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1258 Figure 11: Failure Payload
1262 o Failure Indication (variable length) - Indication of
1263 the failure. This may be for example some flag that
1264 indicates the protocol and the failure status or human
1265 readable failure message. The true length of this
1266 payload is available by calculating it from the SILC
1272 2.3.6 Reject Payload
1274 This payload is sent when some protocol is rejected to be executed.
1275 Other operations MAY send this as well that was rejected. The
1276 indication of the rejection is sent in the payload. The indication
1277 may be binary or human readable data and is protocol dependent.
1283 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
1284 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1286 ~ Reject Indication ~
1288 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1292 Figure 12: Reject Payload
1296 o Reject Indication (variable length) - Indication of
1297 the rejection. This maybe for example some flag that
1298 indicates the protocol and the rejection status or human
1299 readable rejection message. The true length of this
1300 payload is available by calculating it from the SILC
1308 2.3.7 Notify Payload
1310 Notify payload is used to send notify messages. The payload is usually
1311 sent from server to client and from server to router. It is also used
1312 by routers to notify other routers in the network. This payload MAY also
1313 be sent to a channel. Client MUST NOT send this payload. If client
1314 receives this payload it MAY ignore the contents of the payload, however,
1315 notify message SHOULD be audited. Servers and routers MUST process
1318 The payload may only be sent with SILC_PACKET_NOTIFY packet. It MUST
1319 NOT be sent in any other packet type. The following diagram represents
1327 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
1328 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1329 | Notify Type | Payload Length |
1330 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1336 Figure 13: Notify Payload
1340 o Notify Type (2 bytes) - Indicates the type of the notify
1343 o Payload Length (2 bytes) - Length of the entire Notify Payload
1344 including any associated Argument Payloads.
1346 o Argument Nums (1 byte) - Indicates the number of Argument
1347 Payloads associated to this payload. Notify types may define
1348 arguments to be send along the notify message.
1351 The following list of currently defined notify types. The format for
1352 notify arguments is same as in SILC commands described in [SILC4].
1353 Note that all IDs sent in arguments are sent inside ID Payload. Also
1354 note that all passphrases that may be sent inside arguments MUST be
1355 UTF-8 [RFC2279] encoded. Also note that all public keys or certificates
1356 sent inside arguments are actually Public Key Payloads.
1360 0 SILC_NOTIFY_TYPE_NONE
1362 If no specific notify type apply for the notify message this type
1366 Arguments: (1) <message>
1368 The <message> is implementation specific free UTF-8 text string.
1369 Receiver MAY ignore this message.
1372 1 SILC_NOTIFY_TYPE_INVITE
1374 Sent when an client is invited to a channel. This is also sent
1375 when the invite list of the channel is changed. This notify type
1376 is sent between routers and if an client was invited, to the
1377 client as well. In this case the packet is destined to the client.
1380 Arguments: (1) <Channel ID> (2) <channel name>
1381 (3) [<sender Client ID>] (4) [<add | del>]
1384 The <Channel ID> is the channel. The <channel name> is the name
1385 of the channel and is provided because the client which receives
1386 this notify packet may not have a way to resolve the name of the
1387 channel from the <Channel ID>. The <sender Client ID> is the
1388 Client ID which invited the client to the channel. The <add | del>
1389 is an argument of size of 1 byte where 0x00 means adding a client
1390 to invite list, and 0x01 means deleting a client from invite list.
1391 The <invite list>, if present, indicates the information to be
1392 added to or removed from the invite list. The <invite list>
1393 format is defined in [SILC4] with SILC_COMMAND_INVITE command.
1394 When this notify is destined to a client the <add | del> and
1395 <invite list> MUST NOT be sent.
1398 2 SILC_NOTIFY_TYPE_JOIN
1400 Sent when client has joined to a channel. The server MUST
1401 distribute this type to the local clients on the channel and then
1402 send it to its primary router. Note that, when router is joining
1403 the client on behalf of normal server then router MUST send this
1404 notify type locally and globally. The router or server receiving
1405 the packet distributes this type to the local clients on the channel
1406 and broadcast it to the network. This notify is sent also to the
1407 client that joined the channel.
1410 Arguments: (1) [<Client ID>] (2) <Channel ID>
1412 The <Client ID> is the client that joined to the channel indicated
1413 by the <Channel ID>.
1416 3 SILC_NOTIFY_TYPE_LEAVE
1418 Sent when client has left a channel. The server must distribute
1419 this type to the local clients on the channel and then send it
1420 to its primary router. The router or server receiving the
1421 packet distributes this type to the local clients on the channel
1422 and broadcast it to the network.
1425 Arguments: (1) <Client ID>
1427 The <Client ID> is the client which left the channel.
1430 4 SILC_NOTIFY_TYPE_SIGNOFF
1432 Sent when client signoff from SILC network. The server MUST
1433 distribute this type to the local clients on the channel and then
1434 send it to its primary router. The router or server receiving
1435 the packet distributes this type to the local clients on the
1436 channel and broadcast it to the network.
1439 Arguments: (1) <Client ID> (2) <message>
1441 The <Client ID> is the client which left SILC network. The
1442 <message> is free text string indicating the reason of the signoff.
1445 5 SILC_NOTIFY_TYPE_TOPIC_SET
1447 Sent when topic is set/changed on a channel. This type must be
1448 sent only to the clients which are joined on the channel which
1449 topic was set or changed.
1452 Arguments: (1) <ID Payload> (2) <topic>
1454 The <ID Payload> is the ID of the entity who set the topic. It
1455 usually is Client ID but it can be Server ID and Channel ID as well.
1458 6 SILC_NOTIFY_TYPE_NICK_CHANGE
1460 Sent when client changes nick on a channel. The server MUST
1461 distribute this type only to the local clients on the channel
1462 and then send it to its primary router. The router or server
1463 receiving the packet distributes this type to the local clients
1464 on the channel and broadcast it to the network.
1467 Arguments: (1) <Old Client ID> (2) <New Client ID>
1470 The <Old Client ID> is the old ID of the client which changed
1471 the nickname. The <New Client ID> is the new ID generated by
1472 the change of the nickname. The <nickname> is the new nickname.
1473 Note that it is possible to send this notify even if the nickname
1474 has not changed, but client ID was changed.
1477 7 SILC_NOTIFY_TYPE_CMODE_CHANGE
1479 Sent when channel mode has changed. This type MUST be sent only
1480 to the clients which are joined on the channel which mode was
1484 Arguments: (1) <ID Payload> (2) <mode mask>
1485 (3) [<cipher>] (4) <[hmac>]
1486 (5) [<passphrase>] (6) [<founder public key>]
1487 (7) [<add | del>] (8) [<channel public key>]
1489 The <ID Payload> is the ID (usually Client ID but it can be
1490 Server ID as well when the router is enforcing channel mode
1491 change) of the entity which changed the mode. The <mode mask>
1492 is the new mode mask of the channel. The client can safely
1493 ignore the <cipher> argument since the SILC_PACKET_CHANNEL_KEY
1494 packet will force the new channel key change anyway. The <hmac>
1495 argument is important since the client is responsible of setting
1496 the new HMAC and the hmac key into use. The <passphrase> is
1497 the passphrase of the channel, if it was now set. The <founder
1498 public key> argument is sent when the founder mode on the
1499 channel was set. All routers and servers that receive the packet
1500 MUST save the founder's public key so that the founder can
1501 reclaim the channel founder rights back for the channel on any
1502 server in the network.
1504 The <add | del> and <channel public key> is used to add or remove
1505 channel public key from the channel. To add one public key to
1506 channel the SILC_CMODE_CHANNEL_AUTH mode is set and the <add | del>
1507 argument includes 0x00 value, and the <channel public key> is the
1508 public key. To remove one public key from channel public key list
1509 the <add | del> includes 0x01 value and <channel pubkey> is the
1510 public key to be removed. If the SILC_CMODE_CHANNEL_AUTH mode is
1511 unset (and was set earlier) all public keys are removed at once.
1514 8 SILC_NOTIFY_TYPE_CUMODE_CHANGE
1516 Sent when user mode on channel has changed. This type MUST be
1517 sent only to the clients which are joined on the channel where
1518 the target client is on.
1521 Arguments: (1) <ID Payload> (2) <mode mask>
1522 (3) <Target Client ID> (4) [<founder pubkey>]
1524 The <ID Payload> is the ID (usually Client ID but it can be
1525 Server ID as well when the router is enforcing user's mode
1526 change) of the entity which changed the mode. The <mode mask>
1527 is the new mode mask of the channel. The <Target Client ID>
1528 is the client which mode was changed. The <founder pubkey>
1529 is the public key of the channel founder and is sent only
1530 when first setting the channel founder mode using the
1531 SILC_COMMAND_CUMODE command, and when sending this notify.
1534 9 SILC_NOTIFY_TYPE_MOTD
1536 Sent when Message of the Day (motd) is sent to a client.
1539 Arguments: (1) <motd>
1541 The <motd> is the Message of the Day. This notify MAY be
1545 10 SILC_NOTIFY_TYPE_CHANNEL_CHANGE
1547 Sent when channel's ID has changed for a reason or another.
1548 This is sent by normal server to the client. This can also be
1549 sent by router to other server to force the Channel ID change.
1550 The Channel ID MUST be changed to use the new one. When sent
1551 to clients, this type MUST be sent only to the clients which is
1552 joined on the channel.
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.
1570 Arguments: (1) <Server ID> (n) [<Client ID>] [...]
1572 The <Server ID> is the server's ID. The rest of the arguments
1573 are the Client IDs of the clients which are coming from this
1574 server and are thus quitting the SILC network also. If the
1575 maximum number of arguments are reached another
1576 SILC_NOTIFY_TYPE_SERVER_SIGNOFF notify packet MUST be sent.
1577 When this notify packet is sent between routers the Client ID's
1578 MAY be omitted. Server receiving the Client ID's in the payload
1579 may use them directly to remove the client.
1582 12 SILC_NOTIFY_TYPE_KICKED
1584 Sent when a client has been kicked from a channel. This is
1585 sent also to the client which was kicked from the channel.
1586 The client which was kicked from the channel MUST be removed
1587 from the channel. The client MUST also be removed from channel's
1588 invite list if it is explicitly added in the list. This notify
1589 type is always destined to the channel. The router or server
1590 receiving the packet distributes this type to the local clients
1591 on the channel and broadcast it to the network.
1594 Arguments: (1) <Client ID> (2) [<comment>]
1595 (3) <Kicker's Client ID>
1597 The <Client ID> is the client which was kicked from the channel.
1598 The kicker may have set the <comment> to indicate the reason for
1599 the kicking. The <Kicker's Client ID> is the kicker.
1602 13 SILC_NOTIFY_TYPE_KILLED
1604 Sent when a client has been killed from the network. This is sent
1605 also to the client which was killed from the network. The client
1606 which was killed from the network MUST be removed from the network.
1607 This notify type is destined directly to the client which was
1608 killed and to channel if the client is on any channel. The router
1609 or server receiving the packet distributes this type to the local
1610 clients on the channel and broadcast it to the network. The client
1611 MUST also be removed from joined channels invite list if it is
1612 explicitly added in the lists.
1615 Arguments: (1) <Client ID> (2) [<comment>]
1618 The <Client ID> is the client which was killed from the network.
1619 The killer may have set the <comment> to indicate the reason for
1620 the killing. The <Killer's ID> is the killer, which may be
1621 client but also router server.
1624 14 SILC_NOTIFY_TYPE_UMODE_CHANGE
1626 Sent when user's mode in the SILC changes. This type is sent
1627 only between routers as broadcast packet.
1630 Arguments: (1) <Client ID> (2) <mode mask>
1632 The <Client ID> is the client which mode was changed. The
1633 <mode mask> is the new mode mask.
1636 15 SILC_NOTIFY_TYPE_BAN
1638 Sent when the ban list of the channel is changed. This type is
1639 sent only between routers as broadcast packet.
1642 Arguments: (1) <Channel ID> (2) [<add | del>]
1645 The <Channel ID> is the channel which ban list was changed.
1646 The <add | del> is an argument of size of 1 byte where 0x00 means
1647 adding a client to ban list, and 0x01 means deleting a client
1648 from ban list. The <ban list> indicates the information to be
1649 added to or removed from the ban list. The <ban list> format
1650 format is defined in [SILC4] with SILC_COMMAND_BAN command.
1653 16 SILC_NOTIFY_TYPE_ERROR
1655 Sent when an error occurs during processing some SILC procedure.
1656 This is not used when error occurs during command processing, see
1657 [SILC4] for more information about commands and command replies.
1658 This type is sent directly to the sender of the packet whose packet
1659 caused the error. See [SILC1] for definition when this type
1663 Arguments: (1) <Status Type> (n) [...]
1665 The <Status Type> is the error type defined in [SILC4]. Note that
1666 same types are also used with command replies to indicate the
1667 status of a command. Both commands and this notify type share
1668 same status types. Rest of the arguments are status type
1669 dependent and are specified with those status types that can be
1670 sent currently inside this notify type in [SILC4]. The <Status
1671 Type> is size of 1 byte.
1674 17 SILC_NOTIFY_TYPE_WATCH
1676 Sent to indicate change in a watched user. Client can set
1677 nicknames to be watched with SILC_COMMAND_WATCH command, and
1678 receive notifications when they login to network, signoff from
1679 the network or their user mode is changed. This notify type
1680 is used to deliver these notifications. The notify type is
1681 sent directly to the watching client.
1684 Arguments: (1) <Client ID> (2) [<nickname>]
1685 (3) <user mode> (4) [<Notify Type>]
1687 The <Client ID> is the user's Client ID which is being watched,
1688 and the <nickname> is its nickname. If the client just
1689 changed the nickname, then <nickname> is the new nickname, but
1690 the <Client ID> is the old client ID. The <user mode> is the
1691 user's current user mode. The <Notify Type> can be same as the
1692 Notify Payload's Notify Type, and is 16 bit MSB first order value.
1693 If provided it may indicate the notify that occurred for the
1694 client. If client logged in to the network the <Notify Type>
1695 MUST NOT be present.
1698 Notify types starting from 16384 are reserved for private notify
1701 Router server which receives SILC_NOTIFY_TYPE_SIGNOFF,
1702 SILC_NOTIFY_TYPE_SERVER_SIGNOFF, SILC_NOTIFY_TYPE_KILLED,
1703 SILC_NOTIFY_TYPE_NICK_CHANGE and SILC_NOTIFY_TYPE_UMODE_CHANGE
1704 MUST check whether someone in the local cell is watching the nickname
1705 the client has, and send the SILC_NOTIFY_TYPE_WATCH notify to the
1706 watcher, unless the client in case has the SILC_UMODE_REJECT_WATCHING
1707 user mode set. If the watcher client and the client that was
1708 watched is same the notify SHOULD NOT be sent.
1714 Error payload is sent upon error in protocol. Error may occur in
1715 various conditions when server sends this packet. Client MUST NOT
1716 send this payload but MUST be able to accept it. However, client
1717 MAY totally ignore the contents of the packet as server is going to
1718 take action on the error anyway. However, it is recommended
1719 that the client takes error packet seriously.
1725 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
1726 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1730 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1734 Figure 14: Error Payload
1738 o Error Message (variable length) - Human readable error
1739 message as UTF-8 string.
1744 2.3.9 Channel Message Payload
1746 Channel Message Payload is used to send message to channels, a group
1747 of users. These messages can only be sent if client has joined to
1748 some channel. Even though this packet is very common in SILC it
1749 is still special packet. Some special handling on sending and
1750 reception of channel message is required.
1752 Padding MUST be applied into this payload since the payload is
1753 encrypted separately from other parts of the packet with the
1754 channel specific key. Hence the requirement of the padding.
1755 The packet MUST be made multiple by eight (8) or by the block
1756 size of the cipher, which ever is larger.
1758 The SILC header in this packet is encrypted with the session key
1759 of the next receiver of the packet. Nothing else is encrypted
1760 with that key. Thus, the actual packet and padding to be
1761 encrypted with the session key is SILC Header plus padding to it
1762 to make it multiple by eight (8) or multiple by the block size
1763 of the cipher, which ever is larger.
1765 Receiver of the the channel message packet is able to determine
1766 the channel the message is destined to by checking the destination
1767 ID from the SILC Packet header which tells the destination channel.
1768 The original sender of the packet is also determined by checking
1769 the source ID from the header which tells the client which sent
1772 This packet use generic Message Payload as Channel Message Payload.
1773 See section 2.3.2.5 for generic Message Payload.
1777 2.3.10 Channel Key Payload
1779 All traffic in channels are protected by channel specific keys.
1780 Channel Key Payload is used to distribute channel keys to all
1781 clients on the particular channel. Channel keys are sent when
1782 the channel is created, when new user joins to the channel and
1783 whenever a user has left a channel. Server creates the new
1784 channel key and distributes it to the clients by encrypting this
1785 payload with the session key shared between the server and
1786 the client. After that, client starts using the key received
1787 in this payload to protect the traffic on the channel.
1789 The client which is joining to the channel receives its key in the
1790 SILC_COMMAND_JOIN command reply message thus it is not necessary to
1791 send this payload to the entity which sent the SILC_COMMAND_JOIN
1794 Channel keys are cell specific thus every router in the cell have
1795 to create a channel key and distribute it if any client in the
1796 cell has joined to a channel. Channel traffic between cell's
1797 are not encrypted using channel keys, they are encrypted using
1798 normal session keys between two routers. Inside a cell, all
1799 channel traffic is encrypted with the specified channel key.
1800 Channel key SHOULD expire periodically, say, in one hour, in
1801 which case new channel key is created and distributed.
1803 The payload may only be sent with SILC_PACKET_CHANNEL_KEY packet.
1804 It MUST NOT be sent in any other packet type. The following diagram
1805 represents the Channel Key Payload.
1811 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
1812 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1813 | Channel ID Length | |
1814 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1818 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1819 | Cipher Name Length | |
1820 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1824 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1825 | Channel Key Length | |
1826 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1830 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1834 Figure 15: Channel Key Payload
1839 o Channel ID Length (2 bytes) - Indicates the length of the
1840 Channel ID field in the payload, not including any other
1843 o Channel ID (variable length) - The Channel ID of the
1844 channel this key is meant for.
1846 o Cipher Name Length (2 bytes) - Indicates the length of the
1847 Cipher name field in the payload, not including any other
1850 o Cipher Name (variable length) - Name of the cipher used
1851 in the protection of channel traffic. This name is
1852 initially decided by the creator of the channel but it
1853 MAY change during the life time of the channel as well.
1855 o Channel Key Length (2 bytes) - Indicates the length of the
1856 Channel Key field in the payload, not including any other
1859 o Channel Key (variable length) - The actual channel key
1865 2.3.11 Private Message Payload
1867 Private Message Payload is used to send private message between
1868 two clients. The messages are sent only to the specified user
1869 and no other user inside SILC network is able to see the message.
1871 The message can be protected by the session key established by the
1872 SILC Key Exchange Protocol. However, it is also possible to agree
1873 to use a private key to protect just the private messages. It is
1874 for example possible to perform Key Agreement between two clients.
1875 See section 2.3.20 Key Agreement Payload how to perform key
1876 agreement. See also section 2.3.12 Private Message Key Payload
1877 for another way of using private keys with private messages. See
1878 [SILC1] section 4.6 for detailed description for private message
1879 key generation procedure.
1881 If normal session key is used to protect the message, every server
1882 between the sender client and the receiving client MUST decrypt the
1883 packet and always re-encrypt it with the session key of the next
1884 receiver of the packet. See section Client To Client in [SILC1].
1886 When private key is used to protect the message, servers between
1887 the sender and the receiver needs not to decrypt/re-encrypt the
1888 packet. Section Client To Client in [SILC1] gives example of this
1891 This packet use generic Message Payload as Private Message Payload.
1892 See section 2.3.2.5 for generic Message Payload.
1896 2.3.12 Private Message Key Payload
1898 This payload is OPTIONAL and can be used to send private message
1899 key between two clients in the network. The packet is secured with
1900 normal session keys. By default private messages are encrypted
1901 with session keys, and with this payload it is possible to set
1902 private key for private message encryption between two clients.
1904 The receiver of this payload SHOULD verify for example from user
1905 whether user want to receive private message key. Note that there
1906 are other, more secure ways of exchanging private message keys in
1907 the SILC network. Instead of sending this payload it is possible to
1908 negotiate the private message key with SKE protocol using the Key
1909 Agreement payload directly peer to peer, see section 2.3.20.
1911 This payload may only be sent by client to another client. Server
1912 MUST NOT send this payload at any time. After sending this payload
1913 the sender of private messages must set the Private Message Key
1914 flag into SILC Packet Header.
1916 The payload may only be sent with SILC_PACKET_PRIVATE_MESSAGE_KEY
1917 packet. It MUST NOT be sent in any other packet type. The following
1918 diagram represents the Private Message Key Payload.
1928 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
1929 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1930 | Private Message Key Length | |
1931 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1933 ~ Private Message Key ~
1935 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1936 | Cipher Name Length | |
1937 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1941 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1942 | HMAC Name Length | |
1943 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1947 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1951 Figure 16: Private Message Key Payload
1956 o Private Message Key Length (2 bytes) - Indicates the length
1957 of the Private Message Key field in the payload, not including
1960 o Private Message Key (variable length) - The actual private
1961 message key material.
1963 o Cipher Name Length (2 bytes) - Indicates the length of the
1964 Cipher Name field in the payload, not including any other
1967 o Cipher Name (variable length) - Name of the cipher to use
1968 in the private message encryption. If this field does not
1969 exist then the default cipher of the SILC protocol is used.
1970 See the [SILC1] for defined ciphers.
1972 o HMAC Name Length (2 bytes) - Indicates the length of the
1973 HMAC Name field in the payload, not including any other
1976 o HMAC Name (variable length) - Name of the HMAC to use
1977 in the private message MAC computation. If this field does
1978 not exist then the default HMAC of the SILC protocol is used.
1979 See the [SILC1] for defined HMACs.
1984 2.3.13 Command Payload
1986 Command Payload is used to send SILC commands from client to server.
1987 Also server MAY send commands to other servers. The following diagram
1988 represents the Command Payload.
1994 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
1995 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1996 | Payload Length | SILC Command | Arguments Num |
1997 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1998 | Command Identifier |
1999 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2003 Figure 17: Command Payload
2007 o Payload Length (2 bytes) - Length of the entire command
2008 payload including any command argument payloads associated
2011 o SILC Command (1 byte) - Indicates the SILC command. This MUST
2012 be set to non-zero value. If zero (0) value is found in this
2013 field the packet MUST be discarded.
2015 o Arguments Num (1 byte) - Indicates the number of arguments
2016 associated with the command. If there are no arguments this
2017 field is set to zero (0). The arguments MUST follow the
2018 command payload. See section 2.3.2.2 for definition of the
2021 o Command Identifier (2 bytes) - Identifies this command at the
2022 sender's end. The entity which replies to this command MUST
2023 set the value found from this field into the Command Payload
2024 used to send the reply to the sender. This way the sender
2025 can identify which command reply belongs to which originally
2026 sent command. What this field includes is implementation
2027 issue but it is RECOMMENDED that wrapping counter value is
2028 used in the field. Value zero (0) in this field means that
2029 no specific value is set.
2032 See [SILC4] for detailed description of different SILC commands,
2033 their arguments and their reply messages.
2038 2.3.14 Command Reply Payload
2040 Command Reply Payload is used to send replies to the commands. The
2041 Command Reply Payload is identical to the Command Payload thus see
2042 the 2.3.13 section for the payload specification.
2044 The entity which sends the reply packet MUST set the Command Identifier
2045 field in the reply packet's Command Payload to the value it received
2046 in the original command packet.
2048 See SILC Commands in [SILC4] for detailed description of different
2049 SILC commands, their arguments and their reply messages.
2053 2.3.15 Connection Auth Request Payload
2055 Client MAY send this payload to server to request the authentication
2056 method that must be used in authentication protocol. If client knows
2057 this information beforehand this payload is not necessary to be sent.
2058 Server performing authentication with another server MAY also send
2059 this payload to request the authentication method. If the connecting
2060 server already knows this information this payload is not necessary
2063 Server receiving this request SHOULD reply with same payload sending
2064 the mandatory authentication method. Algorithms that may be required
2065 to be used by the authentication method are the ones already
2066 established by the SILC Key Exchange protocol. See section Key
2067 Exchange Start Payload in [SILC3] for detailed information.
2069 The payload may only be sent with SILC_PACKET_CONNECTION_AUTH_REQUEST
2070 packet. It MUST NOT be sent in any other packet type. The following
2071 diagram represents the Connection Auth Request Payload.
2077 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
2078 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2079 | Connection Type | Authentication Method |
2080 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2084 Figure 18: Connection Auth Request Payload
2088 o Connection Type (2 bytes) - Indicates the type of the
2089 connection. The following connection types are defined:
2096 If any other type is found in this field the packet MUST be
2097 discarded and the authentication MUST be failed.
2099 o Authentication Method (2 bytes) - Indicates the authentication
2100 method to be used in the authentication protocol. The following
2101 authentication methods are defined:
2104 1 password (mandatory)
2105 2 public key (mandatory)
2107 If any other type is found in this field the packet MUST be
2108 discarded and the authentication MUST be failed. If this
2109 payload is sent as request to receive the mandatory
2110 authentication method this field MUST be set to zero (0),
2111 indicating that receiver should send the mandatory
2112 authentication method. The receiver sending this payload
2113 to the requesting party, MAY also set this field to zero (0)
2114 to indicate that authentication is not required. In this
2115 case authentication protocol still MUST be started but
2116 server is most likely to respond with SILC_PACKET_SUCCESS
2124 2.3.16 New ID Payload
2126 New ID Payload is a multipurpose payload. It is used to send newly
2127 created ID's from clients and servers. When client connects to server
2128 and registers itself to the server by sending SILC_PACKET_NEW_CLIENT
2129 packet, server replies with this packet by sending the created ID for
2130 the client. Server always creates the ID for the client.
2132 This payload is also used when server tells its router that new client
2133 has registered to the SILC network. In this case the server sends
2134 the Client ID of the client to the router. Similarly when router
2135 distributes information to other routers about the client in the SILC
2136 network this payload is used.
2138 Also, when server connects to router, router use this payload to inform
2139 other routers about new server in the SILC network. However, every
2140 server (or router) creates their own ID's thus the ID distributed by
2141 this payload is not created by the distributor in this case. Servers
2142 create their own ID's. Server registers itself to the network by
2143 sending SILC_PACKET_NEW_SERVER to the router it connected to. The case
2144 is same when router connects to another router.
2146 However, this payload MUST NOT be used to send information about new
2147 channels. New channels are always distributed by sending the dedicated
2148 SILC_PACKET_NEW_CHANNEL packet. Client MUST NOT send this payload.
2149 Both client and server (and router) MAY receive this payload.
2151 The packet use generic ID Payload as New ID Payload. See section
2152 2.3.2.1 for generic ID Payload.
2156 2.3.17 New Client Payload
2158 When client is connected to the server, keys has been exchanged and
2159 connection has been authenticated, client MUST register itself to the
2160 server. Client's first packet after key exchange and authentication
2161 protocols must be SILC_PACKET_NEW_CLIENT. This payload tells server all
2162 the relevant information about the connected user. Server creates a new
2163 client ID for the client when received this payload and sends it to the
2164 client in New ID Payload.
2166 This payload sends username and real name of the user on the remote host
2167 which is connected to the SILC server with SILC client. The server
2168 creates the client ID according the information sent in this payload.
2169 The nickname of the user becomes the nickname sent in this payload.
2171 The payload may only be sent with SILC_PACKET_NEW_CLIENT packet. It
2172 MUST NOT be sent in any other packet type. The following diagram
2173 represents the New Client Payload.
2179 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
2180 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2181 | Username Length | |
2182 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2186 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2187 | Real Name Length | |
2188 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2192 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2196 Figure 19: New Client Payload
2200 o Username Length (2 bytes) - Length of the Username field.
2202 o Username (variable length) - The username of the user on
2203 the host where connecting to the SILC server.
2205 o Real Name Length (2 bytes) - Length of the Real Name field.
2207 o Real Name (variable length) - The real name of the user
2208 on the host where connecting to the SILC server.
2213 2.3.18 New Server Payload
2215 This payload is sent by server when it has completed successfully both
2216 key exchange and connection authentication protocols. The server
2217 MUST register itself to the SILC Network by sending this payload.
2218 The first packet after these key exchange and authentication protocols
2219 is SILC_PACKET_NEW_SERVER packet. The payload includes the Server ID
2220 of the server that it has created by itself. It also includes a
2221 name of the server that is associated to the Server ID.
2223 The payload may only be sent with SILC_PACKET_NEW_SERVER packet. It
2224 MUST NOT be sent in any other packet type. The following diagram
2225 represents the New Server Payload.
2232 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
2233 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2234 | Server ID Length | |
2235 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2239 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2240 | Server Name Length | |
2241 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2245 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2249 Figure 20: New Server Payload
2253 o Server ID Length (2 bytes) - Length of the Server ID Data
2256 o Server ID Data (variable length) - The actual Server ID
2259 o Server Name Length (2 bytes) - Length of the server name
2262 o Server Name (variable length) - The server name.
2267 2.3.19 New Channel Payload
2269 Information about newly created channel is broadcasted to all routers
2270 in the SILC network by sending this packet payload. Channels are
2271 created by router of the cell. Server never creates channels unless
2272 it is a standalone server and it does not have router connection,
2273 in this case server acts as router. Normal server send JOIN command
2274 to the router (after it has received JOIN command from client) which
2275 then processes the command and creates the channel. Client MUST NOT
2276 send this packet. Server MAY send this packet to a router when it is
2277 announcing its existing channels to the router after it has connected
2280 The packet use generic Channel Payload as New Channel Payload. See
2281 section 2.3.2.3 for generic Channel Payload. The Mode Mask field in the
2282 Channel Payload is the mode of the channel.
2286 2.3.20 Key Agreement Payload
2288 This payload is used by clients to request key negotiation between
2289 another client in the SILC Network. The key agreement protocol used
2290 is the SKE protocol. The result of the protocol, the secret key
2291 material, can be used for example as private message key between the
2292 two clients. This significantly adds security as the key agreement
2293 is performed outside the SILC network. The server and router MUST NOT
2296 The sender MAY tell the receiver of this payload the hostname and the
2297 port where the SKE protocol is running in the sender's end. The
2298 receiver MAY then initiate the SKE negotiation with the sender. The
2299 sender MAY also optionally not to include the hostname and the port
2300 of its SKE protocol. In this case the receiver MAY reply to the
2301 request by sending the same payload filled with the receiver's hostname
2302 and the port where the SKE protocol is running. The sender MAY then
2303 initiate the SKE negotiation with the receiver.
2305 This payload may be sent with SILC_PACKET_KEY_AGREEMENT and
2306 SILC_PACKET_FTP packet types. It MUST NOT be sent in any other packet
2307 types. The following diagram represents the Key Agreement Payload.
2313 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
2314 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2315 | Hostname Length | |
2316 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2320 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2322 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2326 Figure 21: Key Agreement Payload
2330 o Hostname Length (2 bytes) - Indicates the length of the
2333 o Hostname (variable length) - The hostname or IP address where
2334 the SKE protocol is running. The sender MAY fill this field
2335 when sending the payload. If the receiver sends this payload
2336 as reply to the request it MUST fill this field.
2338 o Port (4 bytes) - The port where the SKE protocol is bound.
2339 The sender MAY fill this field when sending the payload. If
2340 the receiver sends this payload as reply to the request it
2341 MUST fill this field. This is a 32 bit MSB first order value.
2345 After the key material has been received from the SKE protocol it is
2346 processed as the [SILC3] describes. If the key material is used as
2347 channel private key then the Sending Encryption Key, as defined in
2348 [SILC3] is used as the channel private key. Other key material must
2349 be discarded. The [SILC1] in section 4.6 defines the way to use the
2350 key material if it is intended to be used as private message keys.
2351 Any other use for the key material is undefined.
2355 2.3.21 Resume Router Payload
2357 See the [SILC1] for Resume Router protocol where this payload is
2358 used. The payload may only be sent with SILC_PACKET_RESUME_ROUTER
2359 packet. It MUST NOT be sent in any other packet type. The following
2360 diagram represents the Resume Router Payload.
2366 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
2367 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2368 | Type | Session ID |
2369 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2373 Figure 22: Resume Router Payload
2377 o Type (1 byte) - Indicates the type of the backup resume
2378 protocol packet. The type values are defined in [SILC1].
2380 o Session ID (1 bytes) - Indicates the session ID for the
2381 backup resume protocol. The sender of the packet sets this
2382 value and the receiver MUST set the same value in subsequent
2388 2.3.22 File Transfer Payload
2390 File Transfer Payload is used to perform file transfer protocol
2391 between two entities in the network. The actual file transfer
2392 protocol is always encapsulated inside the SILC Packet. The actual
2393 data stream is also sent peer to peer outside SILC network.
2395 When an entity, usually a client wishes to perform file transfer
2396 protocol with another client in the network, they perform Key Agreement
2397 protocol as described in the section 2.3.20 Key Agreement Payload and
2398 in [SILC3], inside File Transfer Payload. After the Key Agreement
2399 protocol has been performed the subsequent packets in the data stream
2400 will be protected using the new key material. The actual file transfer
2401 protocol is also initialized in this stage. All file transfer protocol
2402 packets are always encapsulated in the File Transfer Payload and
2403 protected with the negotiated key material.
2405 The payload may only be sent with SILC_PACKET_FTP packet. It MUST NOT
2406 be sent in any other packet type. The following diagram represents the
2407 File Transfer Payload.
2418 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
2419 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2425 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2429 Figure 23: File Transfer Payload
2433 o Type (1 byte) - Indicates the type of the file transfer
2434 protocol. The following file transfer protocols has been
2437 1 Secure File Transfer Protocol (SFTP) (mandatory)
2439 If zero (0) value or any unsupported file transfer protocol
2440 type is found in this field the packet must be discarded.
2441 The currently mandatory file transfer protocol is SFTP.
2442 The SFTP protocol is defined in [SFTP].
2444 o Data (variable length) - Arbitrary file transfer data. The
2445 contents and encoding of this field is dependent of the usage
2446 of this payload and the type of the file transfer protocol.
2447 When this payload is used to perform the Key Agreement
2448 protocol, this field include the Key Agreement Payload,
2449 as defined in the section 2.3.20 Key Agreement Payload.
2450 When this payload is used to send the actual file transfer
2451 protocol data, the encoding is defined in the corresponding
2452 file transfer protocol.
2457 2.3.23 Resume Client Payload
2459 This payload is used by client to resume its detached session in the
2460 SILC Network. A client is able to detach itself from the network by
2461 sending SILC_COMMAND_DETACH command to its server. The network
2462 connection to the client is lost but the client remains as valid
2463 client in the network. The client is able to resume the session back
2464 by sending this packet and including the old Client ID, and an
2465 Authentication Payload [SILC1] which the server use to verify with
2466 the detached client's public key. This also implies that the
2467 mandatory authentication method is public key authentication.
2469 Server or router that receives this from the client also sends this,
2470 without the Authentication Payload, to routers in the network so that
2471 they know the detached client has resumed. Refer to the [SILC1] for
2472 detailed description how the detaching and resuming procedure is
2475 The payload may only be sent with SILC_PACKET_RESUME CLIENT packet. It
2476 MUST NOT be sent in any other packet type. The following diagram
2477 represents the Resume Client Payload.
2482 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
2483 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2484 | Client ID Length | |
2485 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
2489 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2491 ~ Authentication Payload ~
2493 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2497 Figure 24: Resume Client Payload
2501 o Client ID Length (1 byte) - The length of the Client ID
2502 field not including any other field.
2504 o Client ID (variable length) - The detached client's Client
2505 ID. The client that sends this payload must know the Client
2508 o Authentication Payload (variable length) - The authentication
2509 payload that the server will verify with the detached client's
2510 public key. If the server doesn't know the public key, it must
2511 retrieve it for example with SILC_COMMAND_GETKEY command.
2519 ID's are used in the SILC network to associate different entities.
2520 The following ID's has been defined to be used in the SILC network.
2525 This is used when other ID type is available at the time.
2529 Server ID to associate servers. See the format of
2534 Client ID to associate clients. See the format of
2539 Channel ID to associate channels. See the format of
2543 When encoding different IDs into the ID Payload, all fields are always
2544 in MSB first order. The IP address, port, and/or the random number
2545 are encoded in the MSB first order.
2549 2.5 Packet Encryption And Decryption
2551 SILC packets are encrypted almost entirely. Only the MAC at the end
2552 of the packet is never encrypted. The SILC Packet header is the first
2553 part of a packet to be encrypted and it is always encrypted with the
2554 key of the next receiver of the packet. The data payload area of the
2555 packet is always entirely encrypted and it is usually encrypted with
2556 the next receiver's key. However, there are some special packet types
2557 and packet payloads that require special encryption process. These
2558 special cases are described in the next sections. First is described
2559 the normal packet encryption process.
2563 2.5.1 Normal Packet Encryption And Decryption
2565 Normal SILC packets are encrypted with the session key of the next
2566 receiver of the packet. The entire SILC Packet header and the packet
2567 data payload is is encrypted with the same key. Padding of the packet
2568 is also encrypted always with the session key, also in special cases.
2569 Computed MAC of the packet MUST NOT be encrypted.
2571 Decryption process in these cases are straightforward. The receiver
2572 of the packet MUST first decrypt the SILC Packet header, or some parts
2573 of it, usually first 16 bytes of it. Then the receiver checks the
2574 packet type from the decrypted part of the header and can determine
2575 how the rest of the packet must be decrypted. If the packet type is
2576 any of the special cases described in the following sections the packet
2577 decryption is special. If the packet type is not among those special
2578 packet types rest of the packet can be decrypted with the same key.
2580 With out a doubt, this sort of decryption processing causes some
2581 overhead to packet decryption, but never the less, is required.
2583 The MAC of the packet is also verified at this point. The MAC is
2584 computed from the ciphertext of the packet so it can be verified
2585 at this stage. The length of the packet need to be known to be able
2586 to verify the MAC from the ciphertext so the first 16 bytes need to
2587 be decrypted to determine the packet length. However, the MAC MUST
2588 be verified from the entire ciphertext.
2592 2.5.2 Channel Message Encryption And Decryption
2594 Channel Messages (Channel Message Payload) are always encrypted with
2595 the channel specific key. However, the SILC Packet header is not
2596 encrypted with that key. As in normal case, the header is encrypted
2597 with the key of the next receiver of the packet, who ever that might
2598 be. Note that in this case the encrypted data area is not touched
2599 at all; it MUST NOT be re-encrypted with the session key.
2601 Receiver of a channel message, who ever that is, is REQUIRED to decrypt
2602 the SILC Packet header to be able to recognize the packet to be as
2603 channel message. This is same procedure as for normal SILC packets.
2604 As the receiver founds the packet to be channel message, rest of the
2605 packet processing is special. Rest of the SILC Packet header is
2606 decrypted with the same session key along with the padding of the
2607 packet. After that the packet is protected with the channel specific
2608 key and thus can be decrypted only if the receiver is the client on
2609 the channel. See section 2.7 Packet Padding Generation for more
2610 information about padding on special packets.
2612 If the receiver of the channel message is router which is routing the
2613 message to another router then it MUST decrypt the Channel Message
2614 payload. Between routers (that is, between cells) channel messages
2615 are protected with session keys shared between the routers. This
2616 causes another special packet processing for channel messages. If
2617 the channel message is received from another router then the entire
2618 packet, including Channel Message payload, MUST be encrypted with the
2619 session key shared between the routers. In this case the packet
2620 decryption process is as with normal SILC packets. Hence, if the
2621 router is sending channel message to another router the Channel
2622 Message payload MUST have been decrypted and MUST be re-encrypted
2623 with the session key shared between the another router. In this
2624 case the packet encryption is as with any normal SILC packet.
2626 It must be noted that this is only when the channel messages are sent
2627 from router to another router. In all other cases the channel
2628 message encryption and decryption is as described above. This
2629 different processing of channel messages with router to router
2630 connection is because channel keys are cell specific. All cells have
2631 their own channel keys thus the channel message traveling from one
2632 cell to another MUST be protected as it would be any normal SILC
2635 If the SILC_CMODE_PRIVKEY channel mode has been set for the channel
2636 then the router cannot decrypt the packet as it does not know the
2637 private key. In this case the entire packet MUST be encrypted with
2638 the session key and sent to the router. The router receiving the
2639 packet MUST check the channel mode and decrypt the packet accordingly.
2643 2.5.3 Private Message Encryption And Decryption
2645 By default, private message in SILC are protected by session keys.
2646 In this case the private message encryption and decryption process is
2647 equivalent to normal packet encryption and decryption.
2649 However, private messages MAY be protected with private message key
2650 which causes the packet to be special packet. The procedure in this
2651 case is very much alike to channel packets. The actual private message
2652 is encrypted with the private message key and other parts of the
2653 packet is encrypted with the session key. See 2.7 Packet Padding
2654 Generation for more information about padding on special packets.
2656 The difference from channel message processing is that server or router
2657 en route never decrypts the actual private message, as it does not
2658 have the key to do that. Thus, when sending packets between router
2659 the processing is same as in any other case as well; the packet's header
2660 and padding is protected by the session key and the data area is not
2663 The true receiver of the private message is able to decrypt the private
2664 message as it shares the key with the sender of the message.
2668 2.6 Packet MAC Generation
2670 Data integrity of a packet is protected by including a message
2671 authentication code (MAC) at the end of the packet. The MAC is computed
2672 from shared secret MAC key, that is established by the SILC Key Exchange
2673 protocol, from packet sequence number, and from the encrypted packet
2674 data. The MAC is always computed after packet is encrypted. This is
2675 so called Encrypt-Then-MAC order; packet is first encrypted, then MAC
2676 is computed from the encrypted data.
2678 The MAC is computed from entire packet. Every bit of data in the packet,
2679 including SILC Packet Header is used in the MAC computing. This way
2680 the entire packet becomes authenticated.
2682 Hence, packet's MAC generation is as follows:
2684 mac = MAC(key, sequence number | Encrypted SILC packet)
2686 The MAC key is negotiated during the SKE protocol. The sequence number
2687 is a 32 bit MSB first value starting from zero for first packet and
2688 increasing for subsequent packets, finally wrapping after 2^32 packets.
2689 The value is never reset, not even after rekey has been performed.
2690 However, rekey MUST be performed before the sequence number wraps
2691 and repeats from zero. Note that the sequence number is incremented only
2692 when MAC is computed for a packet. If packet is not encrypted and MAC is
2693 not computed then the sequence number is not incremented. Hence, the
2694 sequence number is zero for the very first encrypted packet.
2696 See [SILC1] for defined and allowed MAC algorithms.
2700 2.7 Packet Padding Generation
2702 Padding is needed in the packet because the packet is encrypted. It
2703 always MUST be multiple by eight (8) or multiple by the block size
2704 of the cipher, which ever is larger. The padding is always encrypted.
2706 For normal packets the padding is added after the SILC Packet Header
2707 and between the Data Payload area. The padding for normal packets
2708 may be calculated as follows:
2711 padding_length = 16 - (packet_length mod block_size)
2712 if (padding_length < 8)
2713 padding_length += block_size
2716 The `block_size' is the block size of the cipher. The maximum padding
2717 length is 128 bytes, and minimum is 8 bytes. For example, packets that
2718 include a passphrase or a password for authentication purposes SHOULD
2719 pad the packet up to the maximum padding length. The maximum padding
2720 is calculated as follows:
2723 padding_length = 128 - (packet_length mod block_size)
2726 For special packets the padding calculation is different as special
2727 packets may be encrypted differently. In these cases the encrypted
2728 data area MUST already be multiple by the block size thus in this case
2729 the padding is calculated only for SILC Packet Header, not for any
2730 other area of the packet. The same algorithm works in this case as
2731 well, except that the `packet length' is now the SILC Packet Header
2734 The padding MUST be random data, preferably, generated by
2735 cryptographically strong random number generator for each packet
2740 2.8 Packet Compression
2742 SILC Packets MAY be compressed. In this case the data payload area
2743 is compressed and all other areas of the packet MUST remain as they
2744 are. After compression is performed for the data area, the length
2745 field of Packet Header MUST be set to the compressed length of the
2748 The compression MUST always be applied before encryption. When
2749 the packet is received and decrypted the data area MUST be decompressed.
2750 Note that the true sender of the packet MUST apply the compression and
2751 the true receiver of the packet MUST apply the decompression. Any
2752 server or router en route SHOULD NOT decompress the packet.
2758 The sender of the packet MUST assemble the SILC Packet Header with
2759 correct values. It MUST set the Source ID of the header as its own
2760 ID, unless it is forwarding the packet. It MUST also set the Destination
2761 ID of the header to the true destination. If the destination is client
2762 it will be Client ID, if it is server it will be Server ID and if it is
2763 channel it will be Channel ID.
2765 If the sender wants to compress the packet it MUST apply the
2766 compression now. Sender MUST also compute the padding as described
2767 in above sections. Then sender MUST encrypt the packet as has been
2768 described in above sections according whether the packet is normal
2769 packet or special packet. Then sender MUST compute the MAC of the
2770 packet. The computed MAC MUST NOT be encrypted.
2774 2.10 Packet Reception
2776 On packet reception the receiver MUST check that all fields in the
2777 SILC Packet Header are valid. It MUST check the flags of the
2778 header and act accordingly. It MUST also check the MAC of the packet
2779 and if it is to be failed the packet MUST be discarded. Also if the
2780 header of the packet includes any bad fields the packet MUST be
2783 See above sections on the decryption process of the received packet.
2785 The receiver MUST also check that the ID's in the header are valid
2786 ID's. Unsupported ID types or malformed ID's MUST cause packet
2787 rejection. The padding on the reception is always ignored.
2789 The receiver MUST also check the packet type and start parsing the
2790 packet according to the type. However, note the above sections on
2791 special packet types and their parsing.
2797 Routers are the primary entities in the SILC network that takes care
2798 of packet routing. However, normal servers routes packets as well, for
2799 example, when they are routing channel message to the local clients.
2800 Routing is quite simple as every packet tells the true origin and the
2801 true destination of the packet.
2803 It is still RECOMMENDED for routers that has several routing connections
2804 to create route cache for those destinations that has faster route than
2805 the router's primary route. This information is available for the router
2806 when other router connects to the router. The connecting party then
2807 sends all of its locally connected clients, servers and channels. These
2808 informations helps to create the route cache. Also, when new channels
2809 are created to a cell its information is broadcasted to all routers
2810 in the network. Channel ID's are based on router's ID thus it is easy
2811 to create route cache based on these informations. If faster route for
2812 destination does not exist in router's route cache the packet MUST be
2813 routed to the primary route (default route).
2815 However, there are some issues when routing channel messages to group
2816 of users. Routers are responsible of routing the channel message to
2817 other routers, local servers and local clients as well. Routers MUST
2818 send the channel message to only one router in the network, preferably
2819 to the shortest route to reach the channel users. The message can be
2820 routed into either upstream or downstream. After the message is sent
2821 to a router in the network it MUST NOT be sent to any other router in
2822 either same route or other route. The message MUST NOT be routed to
2823 the router it came from.
2825 When routing for example private messages they should be routed to the
2826 shortest route always to reach the destination client as fast as possible.
2828 For server which receives a packet to be routed to its locally connected
2829 client the server MUST check whether the particular packet type is
2830 allowed to be routed to the client. Not all packets may be sent by
2831 some odd entity to client that is indirectly connected to the sender.
2832 See section 2.3 SILC Packet Types and paragraph about indirectly connected
2833 entities and sending packets to them. The section mentions the packets
2834 that may be sent to indirectly connected entities. It is clear that
2835 server cannot send, for example, disconnect packet to client that is not
2836 directly connected to the server.
2838 Routers form a ring in the SILC network. However, routers may have other
2839 direct connections to other routers in the network too. This can cause
2840 interesting routing problems in the network. Since the network is a ring,
2841 the packets usually should be routed into clock-wise direction, or if it
2842 cannot be used then always counter clock-wise (primary route) direction.
2843 Problems may arise when a faster direct route exists and router is routing
2844 a channel message. Currently channel messages must be routed either
2845 in upstream or downstream, they cannot be routed to other direct routes.
2846 The SILC protocol should have a shortest path discovery protocol, and some
2847 existing routing protocol, that can handle a ring network with other
2848 direct routes inside the ring (so called hybrid ring-mesh topology),
2849 MAY be defined to be used with the SILC protocol. Additional
2850 specifications MAY be written on the subject to permeate this
2855 2.12 Packet Broadcasting
2857 SILC packets MAY be broadcasted in SILC network. However, only router
2858 server may send or receive broadcast packets. Client and normal server
2859 MUST NOT send broadcast packets and they MUST ignore broadcast packets
2860 if they receive them. Broadcast packets are sent by setting Broadcast
2861 flag to the SILC packet header.
2863 Broadcasting packets means that the packet is sent to all routers in
2864 the SILC network, except to the router that sent the packet. The router
2865 receiving broadcast packet MUST send the packet to its primary route.
2866 The fact that SILC routers may have several router connections can
2867 cause problems, such as race conditions inside the SILC network, if
2868 care is not taken when broadcasting packets. Router MUST NOT send
2869 the broadcast packet to any other route except to its primary route.
2871 If the primary route of the router is the original sender of the packet
2872 the packet MUST NOT be sent to the primary route. This may happen
2873 if router has several router connections and some other router uses
2874 the router as its primary route.
2876 Routers use broadcast packets to broadcast for example information
2877 about newly registered clients, servers, channels etc. so that all the
2878 routers may keep these informations up to date.
2882 3 Security Considerations
2884 Security is central to the design of this protocol, and these security
2885 considerations permeate the specification. Common security considerations
2886 such as keeping private keys truly private and using adequate lengths for
2887 symmetric and asymmetric keys must be followed in order to maintain the
2888 security of this protocol.
2894 [SILC1] Riikonen, P., "Secure Internet Live Conferencing (SILC),
2895 Protocol Specification", Internet Draft, May 2002.
2897 [SILC3] Riikonen, P., "SILC Key Exchange and Authentication
2898 Protocols", Internet Draft, May 2002.
2900 [SILC4] Riikonen, P., "SILC Commands", Internet Draft, May 2002.
2902 [IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
2905 [IRC-ARCH] Kalt, C., "Internet Relay Chat: Architecture", RFC 2810,
2908 [IRC-CHAN] Kalt, C., "Internet Relay Chat: Channel Management", RFC
2911 [IRC-CLIENT] Kalt, C., "Internet Relay Chat: Client Protocol", RFC
2914 [IRC-SERVER] Kalt, C., "Internet Relay Chat: Server Protocol", RFC
2917 [SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
2920 [PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
2923 [SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
2926 [PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
2927 Infrastructure, Certificate and CRL Profile", RFC 2459,
2930 [Schneier] Schneier, B., "Applied Cryptography Second Edition",
2931 John Wiley & Sons, New York, NY, 1996.
2933 [Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
2936 [OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
2937 RFC 2412, November 1998.
2939 [ISAKMP] Maughan D., et al, "Internet Security Association and
2940 Key Management Protocol (ISAKMP)", RFC 2408, November
2943 [IKE] Harkins D., and Carrel D., "The Internet Key Exchange
2944 (IKE)", RFC 2409, November 1998.
2946 [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
2947 Authentication", RFC 2104, February 1997.
2949 [PKCS1] Kalinski, B., and Staddon, J., "PKCS #1 RSA Cryptography
2950 Specifications, Version 2.0", RFC 2437, October 1998.
2952 [RFC2119] Bradner, S., "Key Words for use in RFCs to Indicate
2953 Requirement Levels", BCP 14, RFC 2119, March 1997.
2955 [SFTP] Ylonen T., and Lehtinen S., "Secure Shell File Transfer
2956 Protocol", Internet Draft, March 2001.
2958 [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO
2959 10646", RFC 2279, January 1998.
2967 Snellmaninkatu 34 A 15
2971 EMail: priikone@iki.fi
2975 6 Full Copyright Statement
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