+++ /dev/null
-.pl 10.0i
-.po 0
-.ll 7.2i
-.lt 7.2i
-.nr LL 7.2i
-.nr LT 7.2i
-.ds LF Riikonen
-.ds RF FORMFEED[Page %]
-.ds CF
-.ds LH Internet Draft
-.ds RH 28 July 2003
-.ds CH
-.na
-.hy 0
-.in 0
-.nf
-Network Working Group P. Riikonen
-Internet-Draft
-draft-riikonen-silc-pp-07.txt 28 July 2003
-Expires: 28 January 2004
-
-.in 3
-
-.ce 2
-SILC Packet Protocol
-<draft-riikonen-silc-pp-07.txt>
-
-.ti 0
-Status of this Memo
-
-This document is an Internet-Draft and is in full conformance with
-all provisions of Section 10 of RFC 2026. Internet-Drafts are
-working documents of the Internet Engineering Task Force (IETF), its
-areas, and its working groups. Note that other groups may also
-distribute working documents as Internet-Drafts.
-
-Internet-Drafts are draft documents valid for a maximum of six months
-and may be updated, replaced, or obsoleted by other documents at any
-time. It is inappropriate to use Internet-Drafts as reference
-material or to cite them other than as "work in progress."
-
-The list of current Internet-Drafts can be accessed at
-http://www.ietf.org/ietf/1id-abstracts.txt
-
-The list of Internet-Draft Shadow Directories can be accessed at
-http://www.ietf.org/shadow.html
-
-The distribution of this memo is unlimited.
-
-
-.ti 0
-Abstract
-
-This memo describes a Packet Protocol used in the Secure Internet Live
-Conferencing (SILC) protocol, specified in the Secure Internet Live
-Conferencing, Protocol Specification [SILC1]. This protocol describes
-the packet types and packet payloads which defines the contents of the
-packets. The protocol provides secure binary packet protocol that
-assures that the contents of the packets are secured and authenticated.
-
-
-
-
-
-
-
-
-
-.ti 0
-Table of Contents
-
-.nf
-1 Introduction .................................................. 3
- 1.1 Requirements Terminology .................................. 4
-2 SILC Packet Protocol .......................................... 4
- 2.1 SILC Packet ............................................... 4
- 2.2 SILC Packet Header ........................................ 5
- 2.3 SILC Packet Types ......................................... 7
- 2.3.1 SILC Packet Payloads ................................ 15
- 2.3.2 Generic payloads .................................... 15
- 2.3.2.1 ID Payload .................................. 15
- 2.3.2.2 Argument Payload ............................ 16
- 2.3.2.3 Argument List Payload ....................... 17
- 2.3.2.4 Channel Payload ............................. 18
- 2.3.2.5 Public Key Payload .......................... 19
- 2.3.2.6 Message Payload ............................. 19
- 2.3.3 Disconnect Payload .................................. 23
- 2.3.4 Success Payload ..................................... 23
- 2.3.5 Failure Payload ..................................... 24
- 2.3.6 Reject Payload ...................................... 24
- 2.3.7 Notify Payload ...................................... 25
- 2.3.8 Error Payload ....................................... 34
- 2.3.9 Channel Message Payload ............................. 34
- 2.3.10 Channel Key Payload ................................ 35
- 2.3.11 Private Message Payload ............................ 37
- 2.3.12 Private Message Key Payload ........................ 37
- 2.3.13 Command Payload .................................... 39
- 2.3.14 Command Reply Payload .............................. 40
- 2.3.15 Connection Auth Request Payload .................... 40
- 2.3.16 New ID Payload ..................................... 41
- 2.3.17 New Client Payload ................................. 42
- 2.3.18 New Server Payload ................................. 43
- 2.3.19 New Channel Payload ................................ 44
- 2.3.20 Key Agreement Payload .............................. 45
- 2.3.21 Resume Router Payload .............................. 46
- 2.3.22 File Transfer Payload .............................. 46
- 2.3.23 Resume Client Payload .............................. 48
- 2.4 SILC ID Types ............................................. 49
- 2.5 Packet Encryption And Decryption .......................... 49
- 2.5.1 Normal Packet Encryption And Decryption ............. 50
- 2.5.2 Channel Message Encryption And Decryption ........... 50
- 2.5.3 Private Message Encryption And Decryption ........... 51
- 2.6 Packet MAC Generation ..................................... 52
- 2.7 Packet Padding Generation ................................. 52
- 2.8 Packet Compression ........................................ 53
- 2.9 Packet Sending ............................................ 53
- 2.10 Packet Reception ......................................... 54
- 2.11 Packet Routing ........................................... 54
- 2.12 Packet Broadcasting ...................................... 55
-3 Security Considerations ....................................... 56
-4 References .................................................... 56
-5 Author's Address .............................................. 58
-6 Full Copyright Statement ...................................... 58
-
-.ti 0
-List of Figures
-
-.nf
-Figure 1: Typical SILC Packet
-Figure 2: SILC Packet Header
-Figure 3: ID Payload
-Figure 4: Argument Payload
-Figure 5: Argument List Payload
-Figure 6: Channel Payload
-Figure 7: Public Key Payload
-Figure 8: Message Payload
-Figure 9: Disconnect Payload
-Figure 10: Success Payload
-Figure 11: Failure Payload
-Figure 12: Reject Payload
-Figure 13: Notify Payload
-Figure 14: Error Payload
-Figure 15: Channel Key Payload
-Figure 16: Private Message Key Payload
-Figure 17: Command Payload
-Figure 18: Connection Auth Request Payload
-Figure 19: New Client Payload
-Figure 20: New Server Payload
-Figure 21: Key Agreement Payload
-Figure 22: Resume Router Payload
-Figure 23: File Transfer Payload
-Figure 24: Resume Client Payload
-
-
-.ti 0
-1. Introduction
-
-This document describes a Packet Protocol used in the Secure Internet
-Live Conferencing (SILC) protocol specified in the Secure Internet Live
-Conferencing, Protocol Specification [SILC1]. This protocol describes
-the packet types and packet payloads which defines the contents of the
-packets. The protocol provides secure binary packet protocol that
-assures that the contents of the packets are secured and authenticated.
-The packet protocol is designed to be compact to avoid unnecessary
-overhead as much as possible. This makes the SILC suitable also in
-environment of low bandwidth requirements such as mobile networks. All
-packet payloads can also be compressed to further reduce the size of
-the packets.
-
-All packets in SILC network are always encrypted and their integrity
-is assured by computed MACs. The protocol defines several packet types
-and packet payloads. Each packet type usually has a specific packet
-payload that actually defines the contents of the packet. Each packet
-also includes a default SILC Packet Header that provides sufficient
-information about the origin and the destination of the packet.
-
-
-.ti 0
-1.1 Requirements Terminology
-
-The keywords MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT, RECOMMENDED,
-MAY, and OPTIONAL, when they appear in this document, are to be
-interpreted as described in [RFC2119].
-
-
-.ti 0
-2 SILC Packet Protocol
-
-.ti 0
-2.1 SILC Packet
-
-SILC packets deliver messages from sender to receiver securely by
-encrypting important fields of the packet. The packet consists of
-default SILC Packet Header, Padding, Packet Payload data, and, packet
-MAC.
-
-The following diagram illustrates typical SILC packet.
-
-.in 5
-.nf
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-| n bytes | 1 - n bytes | n bytes | n bytes
-| SILC Header | Padding | Data Payload | MAC
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-.in 3
-
-.ce
-Figure 1: Typical SILC Packet
-
-
-SILC Header is always the first part of the packet and its purpose
-is to provide information about the packet. It provides for example
-the packet type, origin of the packet and the destination of the packet.
-The header is variable in length. See the following section for
-description of SILC Packet header. Packets without SILC header or
-with malformed SILC header MUST be dropped.
-
-Padding follows the packet header. The purpose of the padding is to
-make the packet multiple by eight (8) or by the block size of the
-cipher used in the encryption, which ever is larger. The maximum
-length of padding is currently 128 bytes. The padding is always
-encrypted. The padding is applied always, even if the packet is
-not encrypted. See the section 2.7 Padding Generation for more
-detailed information.
-
-Data payload area follows padding and it is the actual data of the
-packet. The packet data is the packet payloads defined in this
-protocol. The data payload area is always encrypted.
-
-The last part of SILC packet is the packet MAC that assures the
-integrity of the packet. See the section 2.6 Packet MAC Generation
-for more information. If compression is used the compression is
-always applied before encryption.
-
-All fields in all packet payloads are always in MSB (most significant
-byte first) order.
-
-
-.ti 0
-2.2 SILC Packet Header
-
-The SILC packet header is applied to all SILC packets and it is
-variable in length. The purpose of SILC Packet header is to provide
-detailed information about the packet. The receiver of the packet
-uses the packet header to parse the packet and gain other relevant
-parameters of the packet.
-
-The following diagram represents the SILC packet header.
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Payload Length | Flags | Packet Type |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Pad Length | RESERVED | Source ID Len | Dest ID Len |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Src ID Type | |
-+-+-+-+-+-+-+-+-+ +
-| |
-~ Source ID ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Dst ID Type | |
-+-+-+-+-+-+-+-+-+ +
-| |
-~ Destination ID ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 2: SILC Packet Header
-
-.in 6
-o Payload Length (2 bytes) - Indicates the length of the
- packet not including the padding of the packet.
-
-o Flags (1 byte) - Indicates flags to be used in packet
- processing. Several flags may be set by ORing the flags
- together.
-
- The following flags are reserved for this field:
-
-
- No flags 0x00
-
- In this case the field is ignored.
-
-
- Private Message Key 0x01
-
- Indicates that the packet data MUST include private
- message that is encrypted using private key set by
- client. Servers does not know this key and cannot
- handle the packet, but passes it along. See section
- 2.5.3 Private Message Encryption And Decryption for
- more information.
-
-
- List 0x02
-
- Indicates that the packet consists of list of
- packet payloads indicated by the Packet Type field.
- The payloads are added one after the other. Note that
- there are packet types that must not be used as
- list. Parsing of list packet is done by calculating
- the length of each payload and parsing them one by
- one.
-
-
- Broadcast 0x04
-
- Marks the packet to be broadcasted. Client and normal
- server cannot send broadcast packets. Only router server
- may send broadcast packet. The router receiving of packet
- with this flag set MUST send (broadcast) the packet to
- its primary route. If router has several router connections
- the packet may be sent only to the primary route. See
- section 2.12 Packet Broadcasting for description of
- packet broadcasting.
-
-
- Compressed 0x08
-
- Marks that the payload of the packet is compressed.
- The sender of the packet marks this flag when it
- compresses the payload, and any server or router
- en route to the recipient MUST NOT unset this flag.
- See section 2.8 Packet Compression for description of
- packet compressing.
-
-.in 3
-
-o Packet Type (1 byte) - Indicates the type of the packet.
- Receiver uses this field to parse the packet. See section
- 2.3 SILC Packets for list of defined packet types.
-
-o Pad Length (1 byte) - Indicates the length of the padding
- applied after the SILC Packet header. Maximum length for
- padding is 128 bytes.
-
-o RESERVED (1 byte) - Reserved field and must include a
- zero (0) value.
-
-o Source ID Length (1 byte) - Indicates the length of the
- Source ID field in the header, not including this or any
- other fields.
-
-o Destination ID Length (1 byte) - Indicates the length of the
- Destination ID field in the header, not including this or
- any other fields.
-
-o Src ID Type (1 byte) - Indicates the type of ID in the
- Source ID field. See section 2.4 SILC ID Types for
- defined ID types.
-
-o Source ID (variable length) - The actual source ID that
- indicates which is the original sender of the packet.
-
-o Dst ID Type (1 byte) - Indicates the type of ID in the
- Destination ID field. See section 2.4 SILC ID Types for
- defined ID types.
-
-o Destination ID (variable length) - The actual destination
- ID that indicates which is the end receiver of the packet.
-
-
-
-.ti 0
-2.3 SILC Packet Types
-
-SILC packet types defines the contents of the packet and it is used by
-the receiver to parse the packet. The packet type is 8 bits in length.
-The range for the packet types are from 0 - 255, where 0 is never sent and
-255 is currently reserved for future extensions and MUST NOT be defined to
-any other purpose. Every SILC specification compliant implementation
-SHOULD support all the following packet types.
-
-The below list of the SILC Packet types includes reference to the packet
-payload as well. Packet payloads are the actual packet data area. Each
-packet type defines packet payload which usually may only be sent with
-the specific packet type.
-
-Most of the packets are packets that must be destined directly to entity
-that is connected to the sender. It is not allowed, for example, for a
-router to send SILC_PACKET_DISCONNECT packet to client that is not
-directly connected to the router. However, there are some special packet
-types that may be destined to some entity that the sender does not have
-direct connection with. These packets are for example private message
-packets, channel message packets, command packets and some other packets
-that may be broadcasted in the SILC network. If the packet is allowed to
-be sent to indirectly connected entity it is defined separately in the
-following packet description list. Other packets MUST NOT be sent or
-accepted, if sent, to indirectly connected entities.
-
-Some packets MAY be sent as lists by adding the List flag to the Packet
-Header and constructing multiple packet payloads one after the other.
-When this is allowed it is separately defined in the following list.
-Other packets MUST NOT be sent as list and the List flag MUST NOT be set.
-
-
-List of SILC Packet types are defined as follows.
-
-.in 1
- 0 SILC_PACKET_NONE
-
- This type is reserved and it is never sent.
-
-
- 1 SILC_PACKET_DISCONNECT
-
- This packet is sent to disconnect the remote end. Reason of
- the disconnection is sent inside the packet payload.
-
- Payload of the packet: See section 2.3.3 Disconnect Payload
-
-
- 2 SILC_PACKET_SUCCESS
-
- This packet is sent upon successful execution of a protocol.
- The status of the success is sent in the packet payload.
-
- Payload of the packet: See section 2.3.4 Success Payload
-
-
- 3 SILC_PACKET_FAILURE
-
- This packet is sent upon failure of a protocol. The status
- of the failure is sent in the packet payload.
-
- Payload of the packet: See section 2.3.5 Failure Payload
-
-
- 4 SILC_PACKET_REJECT
-
- This packet MAY be sent upon rejection of a protocol. The
- status of the rejection is sent in the packet payload.
-
- Payload of the packet: See section 2.3.6 Reject Payload
-
-
- 5 SILC_PACKET_NOTIFY
-
- This packet is used to send notify message. The packet is
- usually sent between server and client, but also between
- server and router. Client MUST NOT send this packet. Server
- MAY destine this packet to channel as well when the packet is
- distributed to all clients on the channel. This packet MAY
- be sent as list.
-
- Payload of the packet: See section 2.3.7 Notify Payload.
-
-
- 6 SILC_PACKET_ERROR
-
- This packet is sent when an error occurs. Server MAY
- send this packet. Client MUST NOT send this packet. The
- client MAY entirely ignore the packet, however, server is
- most likely to take action anyway. This packet MAY be sent
- to entity that is indirectly connected to the sender.
-
- Payload of the packet: See section 2.3.8 Error Payload.
-
-
- 7 SILC_PACKET_CHANNEL_MESSAGE
-
- This packet is used to send messages to channels. The packet
- includes Channel ID of the channel and the actual message to
- the channel. Messages sent to the channel are always protected
- by channel specific keys. This packet MAY be sent to entity
- that is indirectly connected to the sender.
-
- Payload of the packet: See section 2.3.9 Channel Message
- Payload
-
-
- 8 SILC_PACKET_CHANNEL_KEY
-
- This packet is used to distribute new key for particular
- channel when server generates it. Each channel has their own
- independent keys that is used to protect the traffic on the
- channel. It is also possible to use channel private keys that
- are not server generated. In this case this packet is not used.
- Client MUST NOT send this packet. This packet MAY be sent to
- entity that is indirectly connected to the sender.
-
- Payload of the packet: See section 2.3.10 Channel Key Payload
-
-
- 9 SILC_PACKET_PRIVATE_MESSAGE
-
- This packet is used to send private messages from client
- to another client. By default, private messages are protected
- by session keys established by normal key exchange protocol.
- However, it is possible to use specific key to protect private
- messages. See [SILC1] for private message key generation.
- This packet MAY be sent to entity that is indirectly connected
- to the sender.
-
- Payload of the packet: See section 2.3.11 Private Message
- Payload
-
-
- 10 SILC_PACKET_PRIVATE_MESSAGE_KEY
-
- This packet can be used to agree about a key to be used to
- protect private messages between two clients. This packet
- is sent inside the SILC network and protected with session
- keys. There are other means of agreeing to use private message
- keys as well, than sending this packet which may not be
- desirable on all situations. See the [SILC1] for private
- message key generation.
-
- Payload of the packet: See section 2.3.12 Private Message
- Key Payload
-
-
- 11 SILC_PACKET_COMMAND
-
- This packet is used to send commands from client to server.
- Server MAY send this packet to other servers as well. All
- commands are listed in their own section SILC Command Types
- in [SILC4]. The contents of this packet is command specific.
- This packet MAY be sent to entity that is indirectly connected
- to the sender.
-
- Payload of the packet: See section 2.3.13 Command Payload
-
-
- 12 SILC_PACKET_COMMAND_REPLY
-
- This packet is sent as reply to the SILC_PACKET_COMMAND packet.
- The contents of this packet is command specific. This packet
- MAY be sent to entity that is indirectly connected to the
- sender. This packet MAY be sent as list.
-
- Payload of the packet: See section 2.3.14 Command Reply
- Payload and section 2.3.13 Command
- Payload
-
-
-
- 13 SILC_PACKET_KEY_EXCHANGE
-
- This packet is used to start SILC Key Exchange Protocol,
- described in detail in [SILC3].
-
- Payload of the packet: Payload of this packet is described
- in the section SILC Key Exchange
- Protocol and its sub sections in
- [SILC3].
-
-
- 14 SILC_PACKET_KEY_EXCHANGE_1
-
- This packet is used as part of the SILC Key Exchange Protocol.
-
- Payload of the packet: Payload of this packet is described
- in the section SILC Key Exchange
- Protocol and its sub sections in
- [SILC3].
-
-
- 15 SILC_PACKET_KEY_EXCHANGE_2
-
- This packet is used as part of the SILC Key Exchange Protocol.
-
- Payload of the packet: Payload of this packet is described
- in the section SILC Key Exchange
- Protocol and its sub sections in
- [SILC3].
-
-
- 16 SILC_PACKET_CONNECTION_AUTH_REQUEST
-
- This packet is used to request an authentication method to
- be used in the SILC Connection Authentication Protocol. If
- initiator of the protocol does not know the mandatory
- authentication method this packet MAY be used to determine it.
- The party receiving this payload SHOULD respond with the same
- packet including the mandatory authentication method.
-
- Payload of the packet: See section 2.3.15 Connection Auth
- Request Payload
-
-
- 17 SILC_PACKET_CONNECTION_AUTH
-
- This packet is used to start and perform the SILC Connection
- Authentication Protocol. This protocol is used to authenticate
- the connecting party. The protocol is described in detail in
- [SILC3].
-
- Payload of the packet: Payload of this packet is described
- in the section SILC Authentication
- Protocol and it sub sections in [SILC].
-
-
- 18 SILC_PACKET_NEW_ID
-
- This packet is used to distribute new IDs from server to
- router and from router to all other routers in SILC network.
- This is used when for example new client is registered to
- SILC network. The newly created IDs of these operations are
- distributed by this packet. Only server may send this packet,
- however, client MUST be able to receive this packet. This
- packet MAY be sent to entity that is indirectly connected
- to the sender. This packet MAY be sent as list.
-
- Payload of the packet: See section 2.3.16 New ID Payload
-
-
- 19 SILC_PACKET_NEW_CLIENT
-
- This packet is used by client to register itself to the
- SILC network. This is sent after key exchange and
- authentication protocols has been completed. Client sends
- various information about itself in this packet to the server.
-
- Payload of the packet: See section 2.3.17 New Client Payload
-
-
- 20 SILC_PACKET_NEW_SERVER
-
- This packet is used by server to register itself to the
- SILC network. This is sent after key exchange and
- authentication protocols has been completed. Server sends
- this to the router it connected to, or, if router was
- connecting, to the connected router. Server sends its
- Server ID and other information in this packet. The client
- MUST NOT send or receive this packet.
-
- Payload of the packet: See section 2.3.18 New Server Payload
-
-
- 21 SILC_PACKET_NEW_CHANNEL
-
- This packet is used to notify routers about newly created
- channel. Channels are always created by the router and it MUST
- notify other routers about the created channel. Router sends
- this packet to its primary route. Client MUST NOT send this
- packet. This packet MAY be sent to entity that is indirectly
- connected to the sender. This packet MAY be sent as list.
-
- Payload of the packet: See section 2.3.19 New Channel Payload
-
-
- 22 SILC_PACKET_REKEY
-
- This packet is used to indicate that re-key must be performed
- for session keys. See section Session Key Regeneration in
- [SILC1] for more information. This packet does not have
- a payload.
-
-
- 23 SILC_PACKET_REKEY_DONE
-
- This packet is used to indicate that re-key is performed and
- new keys must be used hereafter. This packet does not have a
- payload.
-
-
- 24 SILC_PACKET_HEARTBEAT
-
- This packet is used by clients, servers and routers to keep the
- connection alive. It is RECOMMENDED that all servers implement
- keepalive actions and perform it to both direction in a link.
- This packet does not have a payload.
-
-
- 25 SILC_PACKET_KEY_AGREEMENT
-
- This packet is used by clients to request key negotiation
- between another client in the SILC network. If the negotiation
- is started it is performed using the SKE protocol. The result of
- the negotiation, the secret key material, can be used for
- example as private message key. The server and router MUST NOT
- send this packet.
-
- Payload of the packet: See section 2.3.20 Key Agreement Payload
-
-
- 26 SILC_PACKET_RESUME_ROUTER
-
- This packet is used during backup router protocol when the
- original primary router of the cell comes back online and wishes
- to resume the position as being the primary router of the cell.
-
- Payload of the packet: See section 2.3.21 Resume Router Payload
-
-
- 27 SILC_PACKET_FTP
-
- This packet is used to perform an file transfer protocol in the
- SILC session with some entity in the network. The packet is
- multi purpose. The packet is used to tell other entity in the
- network that the sender wishes to perform an file transfer
- protocol. The packet is also used to actually tunnel the
- file transfer protocol stream. The file transfer protocol
- stream is always protected with the SILC binary packet protocol.
-
- Payload of the packet: See section 2.3.22 File Transfer Payload
-
-
- 28 SILC_PACKET_RESUME_CLIENT
-
- This packet is used to resume a client back to the network
- after it has been detached. A client is able to detach from
- the network but the client is still valid client in the network.
- The client may then later resume its session back by sending
- this packet to a server. Routers also use this packet to notify
- other routers in the network that the detached client has resumed.
-
- Payload of the packet: See section 2.3.23 Resume Client Payload
-
-
- 29 - 199
-
- Currently undefined commands.
-
-
- 200 - 254
-
- These packet types are reserved for private use and they will
- not be defined by this document.
-
-
- 255 SILC_PACKET_MAX
-
- This type is reserved for future extensions and currently it
- MUST NOT be sent.
-.in 3
-
-
-.ti 0
-2.3.1 SILC Packet Payloads
-
-All payloads resides in the main data area of the SILC packet. However
-all payloads MUST be at the start of the data area after the SILC
-packet header and padding. All fields in the packet payload are always
-encrypted, as they reside in the data area of the packet which is
-always encrypted. Most of the payloads may only be sent with specific
-packet type which is defined in the description of the payload.
-
-There are some other payloads in SILC as well. However, they are not
-common in the sense that they could be sent at any time. These payloads
-are not described in this section. These are payloads such as SILC
-Key Exchange payloads and so on. These are described in [SILC1],
-[SILC3] and [SILC4].
-
-
-.ti 0
-2.3.2 Generic payloads
-
-This section describes generic payloads that are not associated to any
-specific packet type. They can be used for example inside some other
-packet payload.
-
-
-.ti 0
-2.3.2.1 ID Payload
-
-This payload can be used to send an ID. ID's are variable in length
-thus this payload provides a way to send variable length ID.
-
-The following diagram represents the ID Payload.
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| ID Type | ID Length |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| |
-~ ID Data ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 3: ID Payload
-
-
-.in 6
-o ID Type (2 bytes) - Indicates the type of the ID. See
- section 2.4 SILC ID Types for list of defined ID types.
-
-o ID Length (2 bytes) - Length of the ID Data area not
- including the length of any other fields in the payload.
-
-o ID Data (variable length) - The actual ID data. The encoding
- of the ID data is defined in section 2.4 SILC ID Types.
-.in 3
-
-
-.ti 0
-2.3.2.2 Argument Payload
-
-Argument Payload is used to set arguments for any packet payload that
-need and support arguments, such as commands. Number of arguments
-associated with a packet MUST be indicated by the packet payload which
-need the arguments. Argument Payloads MUST always reside right after
-the packet payload needing the arguments. Incorrect amount of argument
-payloads MUST cause rejection of the packet.
-
-The following diagram represents the Argument Payload.
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Payload Length | Argument Type | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Argument Data ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 4: Argument Payload
-
-
-.in 6
-o Payload Length (2 bytes) - Length of the Argument Data
- field not including the length of any other field in the
- payload.
-
-o Argument Type (1 byte) - Indicates the type of the argument.
- Every argument can have a specific type that are defined
- by the packet payload needing the argument. For example
- every command specify a number for each argument that may be
- associated with the command. By using this number the receiver
- of the packet knows what type of argument this is. If there is
- no specific argument type this field is set to zero (0) value.
-
-o Argument Data (variable length) - Argument data.
-.in 3
-
-
-.ti 0
-2.3.2.3 Argument List Payload
-
-Argument List Payload is a list of Argument Payloads appended one
-after the other. The number of arguments is indicated in the
-payload.
-
-The following diagram represents the Argument List Payload.
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Argument Nums | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Argument Payloads ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 5: Argument List Payload
-
-
-.in 6
-o Argument Nums (2 bytes) - Indicates the number of Argument
- Payloads. If zero (0) value is found in this field no
- arguments are present.
-
-o Argument Payloads (variable length) - The Argument Payloads
- appended one after the other. The payloads can be decoded
- since the length of the payload is indicated in each of
- the Argument Payload.
-.in 3
-
-
-
-
-.ti 0
-2.3.2.4 Channel Payload
-
-Generic Channel Payload may be used to send information about a channel,
-its name, the Channel ID and a mode.
-
-The following diagram represents the Channel Payload.
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Channel Name Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Channel Name ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Channel ID Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Channel ID ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Mode Mask |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 6: New Channel Payload
-
-
-.in 6
-o Channel Name Length (2 bytes) - Length of the Channel Name
- field.
-
-o Channel Name (variable length) - The name of the channel.
-
-o Channel ID Length (2 bytes) - Length of the Channel ID field.
-
-o Channel ID (variable length) - The encoded Channel ID.
-
-o Mode Mask (4 bytes) - A mode. This can be the mode of the
- channel but it can also be the mode of a client on the
- channel. The contents of this field is dependent of the
- usage of this payload. The usage is defined separately
- when this payload is used. This is a 32 bit MSB first value.
-.in 3
-
-
-
-
-
-
-.ti 0
-2.3.2.5 Public Key Payload
-
-Generic Public Key Payload may be used to send different type of
-public keys and certificates.
-
-The following diagram represents the Public Key Payload.
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Public Key Length | Public Key Type |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| |
-~ Public Key (or certificate) ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 7: Public Key Payload
-
-
-.in 6
-o Public Key Length (2 bytes) - The length of the Public Key
- (or certificate) field, not including any other field.
-
-o Public Key Type (2 bytes) - The public key (or certificate)
- type. This field indicates the type of the public key in
- the packet. See the [SILC3] for defined public key types.
-
-o Public Key (or certificate) (variable length) - The
- encoded public key or certificate data.
-.in 3
-
-
-.ti 0
-2.3.2.6 Message Payload
-
-Generic Message Payload can be used to send messages in SILC. It
-is used to send channel messages and private messages.
-
-The following diagram represents the Message Payload.
-
-(*) indicates that the field is not encrypted.
-
-
-
-
-
-
-
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Message Flags | Message Length |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| |
-~ Message Data ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Padding Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Padding ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| |
-~ Initial Vector * ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| |
-~ MAC * ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 8: Message Payload
-
-
-.in 6
-o Message Flags (2 bytes) - Includes the Message Flags of the
- message. The flags can indicate a reason or a purpose for
- the message. The following Message Flags are defined:
-
- 0x0000 SILC_MESSAGE_FLAG_NONE
-
- No specific flags set.
-
- 0x0001 SILC_MESSAGE_FLAG_AUTOREPLY
-
- This message is an automatic reply to an earlier
- received message.
-
- 0x0002 SILC_MESSAGE_FLAG_NOREPLY
-
- There should not be reply messages to this
- message.
-
- 0x0004 SILC_MESSAGE_FLAG_ACTION
-
- The sender is performing an action and the message
- is the indication of the action.
-
- 0x0008 SILC_MESSAGE_FLAG_NOTICE
-
- The message is for example an informational notice
- type message.
-
- 0x0010 SILC_MESSAGE_FLAG_REQUEST
-
- This is a generic request flag to send request
- messages. A separate document should define any
- payloads associated to this flag.
-
- 0x0020 SILC_MESSAGE_FLAG_SIGNED
-
- This flag indicates that the message is signed
- with sender's private key and thus can be verified
- by the receiver using the sender's public key. A
- separate document should define the detailed procedure
- of the signing process and any associated payloads
- for this flag.
-
- 0x0040 SILC_MESSAGE_FLAG_REPLY
-
- This is a generic reply flag to send a reply to
- previously received request. A separate document
- should define any payloads associated to this flag.
-
- 0x0080 SILC_MESSAGE_FLAG_DATA
-
- This is a generic data flag, indicating that the
- message includes some data which can be interpreted
- in a specific way. Using this flag any kind of data
- can be delivered inside message payload. A separate
- document should define how this flag is interpreted
- and define any associated payloads.
-
- 0x0100 SILC_MESSAGE_FLAG_UTF8
-
- This flag indicates that the message is UTF-8 encoded
- textual message. When sending text messages in SILC
- this flag SHOULD be used. When this flag is used the
- text sent as message MUST be UTF-8 encoded.
-
- 0x0200 - 0x0800 RESERVED
-
- Reserved for future flags.
-
- 0x1000 - 0x8000 PRIVATE RANGE
-
- Private range for free use.
-
-o Message Length (2 bytes) - Indicates the length of the
- Message Data field in the payload, not including any
- other field.
-
-o Message Data (variable length) - The actual message data.
-
-o Padding Length (2 bytes) - Indicates the length of the
- Padding field in the payload, not including any other
- field.
-
-o Padding (variable length) - If this payload is used as
- channel messages, the padding MUST be applied because
- this payload is encrypted separately from other parts
- of the packet. If this payload is used as private
- messages, the padding is present only when the payload
- is encrypted with private message key. If encrypted
- with session keys this field MUST NOT be present and the
- Padding Length field includes a zero (0) value. The
- padding SHOULD be random data.
-
-o Initial Vector (variable length) - This field MUST be
- present when this payload is used as channel messages.
- The IV SHOULD be random data for each channel message.
-
- When encrypting private messages with session keys this
- field MUST NOT be present. For private messages this
- field is present only when encrypting with a static
- private message key (pre-shared key). If randomly
- generated key material is used this field MUST NOT be
- present. Also, If Key Agreement (SKE) was used to
- negotiate fresh key material for private message key
- this field MUST NOT be present. See the section 4.6
- in [SILC1] for more information about IVs when
- encrypting private messages.
-
- This field includes the initial vector used in message
- encryption. It need to be used in the packet decryption
- as well. Contents of this field depends on the encryption
- algorithm and encryption mode. This field is not encrypted,
- is not included in padding calculation and its length
- equals to cipher's block size. This field is authenticated
- by the message MAC.
-
-o MAC (variable length) - The MAC computed from the
- Message Flags, Message Length, Message Data, Padding Length,
- Padding and Initial Vector fields in that order. The MAC
- is computed after the payload is encrypted. This is so
- called Encrypt-Then-MAC order; first encrypt, then compute
- MAC from ciphertext. The MAC protects the integrity of
- the Message Payload. Also, when used as channel messages
- it is possible to have multiple private channel keys set,
- and receiver can use the MAC to verify which of the keys
- must be used in decryption. This field is not encrypted.
- This field is authenticated by the SILC packet MAC.
-.in 3
-
-
-.ti 0
-2.3.3 Disconnect Payload
-
-Disconnect payload is sent upon disconnection. Reason of the
-disconnection is sent to the disconnected party in the payload.
-
-The payload may only be sent with SILC_PACKET_DISCONNECT packet. It
-MUST NOT be sent in any other packet type. The following diagram
-represents the Disconnect Payload.
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Status | |
-+-+-+-+-+-+-+-+-+ +
-| |
-~ Disconnect Message ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 9: Disconnect Payload
-
-.in 6
-o Status (1 byte) - Indicates the Status Type, defined in [SILC3]
- for the reason of disconnection.
-
-o Disconnect Message (variable length) - Human readable UTF-8
- encoded string indicating reason of the disconnection. This
- field MAY be omitted.
-.in 3
-
-
-.ti 0
-2.3.4 Success Payload
-
-Success payload is sent when some protocol execution is successfully
-completed. The payload is simple; indication of the success is sent.
-This may be any data, including binary or human readable data, and
-it is protocol dependent.
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| |
-~ Success Indication ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 10: Success Payload
-
-
-.in 6
-o Success Indication (variable length) - Indication of
- the success. This may be for example some flag that
- indicates the protocol and the success status or human
- readable success message. The true length of this
- payload is available by calculating it from the SILC
- Packet Header.
-.in 3
-
-
-.ti 0
-2.3.5 Failure Payload
-
-This is opposite of Success Payload. Indication of failure of
-some protocol is sent in the payload.
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| |
-~ Failure Indication ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 11: Failure Payload
-
-
-.in 6
-o Failure Indication (variable length) - Indication of
- the failure. This may be for example some flag that
- indicates the protocol and the failure status or human
- readable failure message. The true length of this
- payload is available by calculating it from the SILC
- Packet Header.
-.in 3
-
-
-.ti 0
-2.3.6 Reject Payload
-
-This payload is sent when some protocol is rejected to be executed.
-Other operations MAY send this as well that was rejected. The
-indication of the rejection is sent in the payload. The indication
-may be binary or human readable data and is protocol dependent.
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| |
-~ Reject Indication ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 12: Reject Payload
-
-
-.in 6
-o Reject Indication (variable length) - Indication of
- the rejection. This maybe for example some flag that
- indicates the protocol and the rejection status or human
- readable rejection message. The true length of this
- payload is available by calculating it from the SILC
- Packet Header.
-.in 3
-
-
-
-.ti 0
-2.3.7 Notify Payload
-
-Notify payload is used to send notify messages. The payload is usually
-sent from server to client and from server to router. It is also used
-by routers to notify other routers in the network. This payload MAY also
-be sent to a channel. Client MUST NOT send this payload. When this
-packet is received by client it SHOULD process it. Servers and routers
-MUST process notify packets.
-
-The payload may only be sent with SILC_PACKET_NOTIFY packet. It MUST
-NOT be sent in any other packet type. The following diagram represents
-the Notify Payload.
-
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Notify Type | Payload Length |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Argument Nums |
-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 13: Notify Payload
-
-
-.in 6
-o Notify Type (2 bytes) - Indicates the type of the notify
- message.
-
-o Payload Length (2 bytes) - Length of the entire Notify Payload
- including any associated Argument Payloads.
-
-o Argument Nums (1 byte) - Indicates the number of Argument
- Payloads associated to this payload. Notify types may define
- arguments to be sent along the notify message.
-.in 3
-
-The following list of currently defined notify types. The format for
-notify arguments is same as in SILC commands described in [SILC4].
-Note that all IDs sent in arguments are sent inside ID Payload. Also
-note that all passphrases that may be sent inside arguments MUST be
-UTF-8 [RFC2279] encoded. Also note that all public keys or certificates
-sent inside arguments are actually Public Key Payloads.
-
-
-.in 6
-0 SILC_NOTIFY_TYPE_NONE
-
- If no specific notify type apply for the notify message this type
- MAY be used.
-
- Max Arguments: 1
- Arguments: (1) <message>
-
- The <message> is implementation specific free UTF-8 text string.
- Receiver MAY ignore this message.
-
-
-1 SILC_NOTIFY_TYPE_INVITE
-
- Sent when an client is invited to a channel. This is also sent
- when the invite list of the channel is changed. This notify type
- is sent between routers and if an client was invited, to the
- client as well. In this case the packet is destined to the
- client.
-
- Max Arguments: 5
- Arguments: (1) <Channel ID> (2) <channel name>
- (3) [<sender Client ID>] (4) [<add | del>]
- (5) [<invite list>]
-
- The <Channel ID> is the channel. The <channel name> is the name
- of the channel and is provided because the client which receives
- this notify packet may not have a way to resolve the name of the
- channel from the <Channel ID>. The <sender Client ID> is the
- Client ID which invited the client to the channel. The
- <add | del> is an argument of size of 1 byte where 0x00 means
- adding a client to invite list, and 0x01 means deleting a client
- from invite list. The <invite list>, if present, indicates the
- information to be added to or removed from the invite list.
- The <invite list> format is defined in [SILC4] with
- SILC_COMMAND_INVITE command. When this notify is destined to
- a client the <add | del> and <invite list> MUST NOT be sent.
-
-
-2 SILC_NOTIFY_TYPE_JOIN
-
- Sent when client has joined to a channel. The server MUST
- distribute this type to the local clients on the channel and then
- send it to its primary router. Note that, when router is joining
- the client on behalf of normal server then router MUST send this
- notify type locally and globally. The router or server receiving
- the packet distributes this type to the local clients on the
- channel and broadcast it to the network. This notify is sent
- also to the client that joined the channel.
-
- Max Arguments: 2
- Arguments: (1) [<Client ID>] (2) <Channel ID>
-
- The <Client ID> is the client that joined to the channel
- indicated by the <Channel ID>.
-
-
-3 SILC_NOTIFY_TYPE_LEAVE
-
- Sent when client has left a channel. The server must distribute
- this type to the local clients on the channel and then send it
- to its primary router. The router or server receiving the
- packet distributes this type to the local clients on the channel
- and broadcast it to the network. This notify MUST NOT be sent to
- the leaving client.
-
- Max Arguments: 1
- Arguments: (1) <Client ID>
-
- The <Client ID> is the client which left the channel.
-
-
-4 SILC_NOTIFY_TYPE_SIGNOFF
-
- Sent when client signoff from SILC network. The server MUST
- distribute this type to the local clients on the channel and
- then send it to its primary router. The router or server
- receiving the packet distributes this type to the local clients
- on the channel and broadcast it to the network. This notify
- MUST NOT be sent to the quitting client.
-
- Max Arguments: 2
- Arguments: (1) <Client ID> (2) <message>
-
- The <Client ID> is the client which left SILC network. The
- <message> is free text string indicating the reason of the
- signoff.
-
-
-5 SILC_NOTIFY_TYPE_TOPIC_SET
-
- Sent when topic is set/changed on a channel. This type may be
- sent only to the clients which are joined on the channel which
- topic was just set or changed. The packet is destined to the
- channel.
-
- Max Arguments: 2
- Arguments: (1) <ID Payload> (2) <topic>
-
- The <ID Payload> is the ID of the entity who set the topic.
- It usually is Client ID but it can be Server ID and Channel ID
- as well.
-
-
-6 SILC_NOTIFY_TYPE_NICK_CHANGE
-
- Sent when client changes nick on a channel. The server MUST
- distribute this type only to the local clients on the channel
- and then send it to its primary router. The router or server
- receiving the packet distributes this type to the local clients
- on the channel and broadcast it to the network. This packet is
- destined directly to the sent entity. This MUST be sent to those
- clients that are joined on same channels as the client that
- changed the nickname. This notify MUST NOT be sent multiple
- times to the same recipient. This notify MUST be sent also to
- the client that changed the nickname.
-
- Max Arguments: 3
- Arguments: (1) <Old Client ID> (2) <New Client ID>
- (3) <nickname>
-
- The <Old Client ID> is the old ID of the client which changed
- the nickname. The <New Client ID> is the new ID generated by
- the change of the nickname. The <nickname> is the new nickname.
- Note that it is possible to send this notify even if the
- nickname has not changed, but client ID was changed.
-
-
-7 SILC_NOTIFY_TYPE_CMODE_CHANGE
-
- Sent when channel mode has changed. This type MUST be sent only
- to the clients which are joined on the channel which mode was
- changed. This packet is destined to the channel.
-
- Max Arguments: 8
- Arguments: (1) <ID Payload> (2) <mode mask>
- (3) [<cipher>] (4) <[hmac>]
- (5) [<passphrase>] (6) [<founder public key>]
- (7) [<add | del>] (8) [<channel public key>]
-
- The <ID Payload> is the ID (usually Client ID but it can be
- Server ID as well when the router is enforcing channel mode
- change) of the entity which changed the mode. The <mode mask>
- is the new mode mask of the channel. The client can safely
- ignore the <cipher> argument since the SILC_PACKET_CHANNEL_KEY
- packet will force the new channel key change anyway. The <hmac>
- argument is important since the client is responsible of setting
- the new HMAC and the hmac key into use. The <passphrase> is
- the passphrase of the channel, if it was now set. The <founder
- public key> argument is sent when the founder mode on the
- channel was set. All routers and servers that receive the packet
- MUST save the founder's public key so that the founder can
- reclaim the channel founder rights back for the channel on any
- server in the network.
-
- The <add | del> and <channel public key> is used to add or
- remove channel public key from the channel. To add one public
- key to channel the SILC_CMODE_CHANNEL_AUTH mode is set and the
- <add | del> argument includes 0x00 value, and the <channel
- public key> is the public key. To remove one public key from
- channel public key list the <add | del> includes 0x01 value and
- <channel pubkey> is the public key to be removed. If the
- SILC_CMODE_CHANNEL_AUTH mode is unset (and was set earlier)
- all public keys are removed at once.
-
-
-8 SILC_NOTIFY_TYPE_CUMODE_CHANGE
-
- Sent when user mode on channel has changed. This type MUST be
- sent only to the clients which are joined on the channel where
- the target client is on. This packet is destined to the channel.
-
- Max Arguments: 4
- Arguments: (1) <ID Payload> (2) <mode mask>
- (3) <Target Client ID> (4) [<founder pubkey>]
-
- The <ID Payload> is the ID (usually Client ID but it can be
- Server ID as well when the router is enforcing user's mode
- change) of the entity which changed the mode. The <mode mask>
- is the new mode mask of the channel. The <Target Client ID>
- is the client which mode was changed. The <founder pubkey>
- is the public key of the channel founder and may be sent only
- when first time setting the channel founder mode using the
- SILC_COMMAND_CUMODE command, and when sending this notify.
-
-
-9 SILC_NOTIFY_TYPE_MOTD
-
- Sent when Message of the Day (motd) is sent to a client.
-
- Max Arguments: 1
- Arguments: (1) <motd>
-
- The <motd> is the Message of the Day. This notify MAY be
- ignored.
-
-
-10 SILC_NOTIFY_TYPE_CHANNEL_CHANGE
-
- Sent when channel's ID has changed for a reason or another.
- This is sent by normal server to the client. This can also be
- sent by router to other server to force the Channel ID change.
- The Channel ID MUST be changed to use the new one. When sent
- to clients, this type MUST be sent only to the clients which are
- joined on the channel. This packet is destined to the sent
- entity.
-
- Max Arguments: 2
- Arguments: (1) <Old Channel ID> (2) <New Channel ID>
-
- The <Old Channel ID> is the channel's old ID and the <New
- Channel ID> is the new one that MUST replace the old one.
- Server which receives this from router MUST re-announce the
- channel to the router by sending SILC_PACKET_NEW_CHANNEL packet
- with the new Channel ID.
-
-
-11 SILC_NOTIFY_TYPE_SERVER_SIGNOFF
-
- Sent when server quits SILC network. Those clients from this
- server that are on channels must be removed from the channel.
- This packet is destined to the sent entity.
-
- Max Arguments: 256
- Arguments: (1) <Server ID> (n) [<Client ID>] [...]
-
- The <Server ID> is the server's ID. The rest of the arguments
- are the Client IDs of the clients which are coming from this
- server and are thus quitting the SILC network also. If the
- maximum number of arguments are reached another
- SILC_NOTIFY_TYPE_SERVER_SIGNOFF notify packet MUST be sent.
- When this notify packet is sent between routers the Client ID's
- MAY be omitted. Server receiving the Client ID's in the payload
- may use them directly to remove the client.
-
-
-12 SILC_NOTIFY_TYPE_KICKED
-
- Sent when a client has been kicked from a channel. This MUST
- also be sent to the client which was kicked from the channel.
- The client which was kicked from the channel MUST be removed
- from the channel. The client MUST also be removed from channel's
- invite list if it is explicitly added in the list. This packet
- is destined to the channel. The router or server receiving the
- packet distributes this type to the local clients on the channel
- and broadcast it to the network.
-
- Max Arguments: 3
- Arguments: (1) <Client ID> (2) [<comment>]
- (3) <Kicker's Client ID>
-
- The <Client ID> is the client which was kicked from the channel.
- The kicker may have set the <comment> to indicate the reason for
- the kicking. The <Kicker's Client ID> is the kicker.
-
-
-13 SILC_NOTIFY_TYPE_KILLED
-
- Sent when a client has been killed from the network. This MUST
- also be sent to the client which was killed from the network.
- This notify MUST be sent to those clients which are joined on
- same channels as the killed client. The client which was killed
- MUST be removed from the network. This packet is destined
- directly to the sent entity. The router or server receiving
- the packet distributes this type to the local clients on the
- channel and broadcast it to the network. The client MUST also
- be removed from joined channels invite list if it is explicitly
- added in the lists. This notify MUST NOT be sent multiple
- times to same recipient.
-
- Max Arguments: 3
- Arguments: (1) <Client ID> (2) [<comment>]
- (3) <Killer's ID>
-
- The <Client ID> is the client which was killed from the network.
- The killer may have set the <comment> to indicate the reason for
- the killing. The <Killer's ID> is the killer, which may be
- client but also router server.
-
-
-14 SILC_NOTIFY_TYPE_UMODE_CHANGE
-
- Sent when user's mode in the SILC changes. This type is sent
- only between routers as broadcast packet.
-
- Max Arguments: 2
- Arguments: (1) <Client ID> (2) <mode mask>
-
- The <Client ID> is the client which mode was changed. The
- <mode mask> is the new mode mask.
-
-
-15 SILC_NOTIFY_TYPE_BAN
-
- Sent when the ban list of the channel is changed. This type is
- sent only between routers as broadcast packet.
-
- Max Arguments: 3
- Arguments: (1) <Channel ID> (2) [<add | del>]
- (3) [<ban list>]
-
- The <Channel ID> is the channel which ban list was changed.
- The <add | del> is an argument of size of 1 byte where 0x00 means
- adding a client to ban list, and 0x01 means deleting a client
- from ban list. The <ban list> indicates the information to be
- added to or removed from the ban list. The <ban list> format
- format is defined in [SILC4] with SILC_COMMAND_BAN command.
-
-
-16 SILC_NOTIFY_TYPE_ERROR
-
- Sent when an error occurs during processing some SILC procedure.
- This is not used when error occurs during command processing, see
- [SILC4] for more information about commands and command replies.
- This type is sent directly to the sender of the packet whose
- packet caused the error. See [SILC1] for definition when this
- type can be sent.
-
- Max Arguments: 256
- Arguments: (1) <Status Type> (n) [...]
-
- The <Status Type> is the error type defined in [SILC4]. Note
- that same types are also used with command replies to indicate
- the status of a command. Both commands and this notify type
- share same status types. Rest of the arguments are status type
- dependent and are specified with those status types that can be
- sent currently inside this notify type in [SILC4]. The <Status
- Type> is size of 1 byte.
-
-
-17 SILC_NOTIFY_TYPE_WATCH
-
- Sent to indicate change in a watched user. Client can set
- nicknames to be watched with SILC_COMMAND_WATCH command, and
- receive notifications when they login to network, signoff from
- the network or their user mode is changed. This notify type
- is used to deliver these notifications. The notify type is
- sent directly to the watching client.
-
- Max Arguments: 4
- Arguments: (1) <Client ID> (2) [<nickname>]
- (3) <user mode> (4) [<Notify Type>]
-
- The <Client ID> is the user's Client ID which is being watched,
- and the <nickname> is its nickname. If the client just
- changed the nickname, then <nickname> is the new nickname, but
- the <Client ID> is the old client ID. The <user mode> is the
- user's current user mode. The <Notify Type> can be same as the
- Notify Payload's Notify Type, and is 16 bit MSB first order
- value. If provided it may indicate the notify that occurred
- for the client. If client logged in to the network the
- <Notify Type> MUST NOT be present.
-.in 3
-
-Notify types starting from 16384 are reserved for private notify
-message types.
-
-Router server which receives SILC_NOTIFY_TYPE_SIGNOFF,
-SILC_NOTIFY_TYPE_SERVER_SIGNOFF, SILC_NOTIFY_TYPE_KILLED,
-SILC_NOTIFY_TYPE_NICK_CHANGE and SILC_NOTIFY_TYPE_UMODE_CHANGE
-MUST check whether someone in the local cell is watching the nickname
-the client has, and send the SILC_NOTIFY_TYPE_WATCH notify to the
-watcher, unless the watched client in case has the user mode
-SILC_UMODE_REJECT_WATCHING set. If the watcher client and the client
-that was watched is same the notify SHOULD NOT be sent.
-
-
-
-
-
-.ti 0
-2.3.8 Error Payload
-
-Error payload is sent upon error in protocol. Error may occur in
-various conditions when server sends this packet. Client MUST NOT
-send this payload but MUST be able to accept it. However, client
-MAY ignore the contents of the packet as server is going to take
-action on the error anyway. However, it is recommended that the
-client takes error packet seriously.
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| |
-~ Error Message ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 14: Error Payload
-
-
-.in 6
-o Error Message (variable length) - Human readable error
- message as UTF-8 string.
-.in 3
-
-
-.ti 0
-2.3.9 Channel Message Payload
-
-Channel Message Payload is used to send message to channels, a group
-of users. These messages can only be sent if client has joined to
-some channel. Even though this packet is very common in SILC it
-is still special packet. Some special handling on sending and
-reception of channel message is required.
-
-Padding MUST be applied into this payload since the payload is
-encrypted separately from other parts of the packet with the
-channel specific key. Hence the requirement of the padding.
-The packet MUST be made multiple by eight (8) or by the block
-size of the cipher, which ever is larger.
-
-The SILC header in this packet is encrypted with the session key
-of the next receiver of the packet. Nothing else is encrypted
-with that key. Thus, the actual packet and padding to be
-encrypted with the session key is SILC Header plus padding to it.
-
-Receiver of the the channel message packet is able to determine
-the channel the message is destined to by checking the destination
-ID from the SILC Packet header which tells the destination channel.
-The original sender of the packet is also determined by checking
-the source ID from the header which tells the client which sent
-the message.
-
-This packet use generic Message Payload as Channel Message Payload.
-See section 2.3.2.5 for generic Message Payload.
-
-
-.ti 0
-2.3.10 Channel Key Payload
-
-All traffic in channels are protected by channel specific keys.
-Channel Key Payload is used to distribute channel keys to all
-clients on the particular channel. Channel keys are sent when
-the channel is created, when new user joins to the channel and
-whenever a user has left a channel. Server creates the new
-channel key and distributes it to the clients by encrypting this
-payload with the session key shared between the server and
-the client. After that, client MUST start using the key received
-in this payload to protect the traffic on the channel.
-
-The client which is joining to the channel receives its key in the
-SILC_COMMAND_JOIN command reply message thus it is not necessary to
-send this payload to the entity which sent the SILC_COMMAND_JOIN
-command.
-
-Channel keys are cell specific thus every router in the cell have
-to create a channel key and distribute it if any client in the
-cell has joined to a channel. Channel traffic between cell's
-are not encrypted using channel keys, they are encrypted using
-normal session keys between two routers. Inside a cell, all
-channel traffic is encrypted with the specified channel key.
-Channel key SHOULD expire periodically, say, in one hour, in
-which case new channel key is created and distributed.
-
-Note that, this packet is not used if SILC_CMODE_PRIVKEY mode is set
-on channel. This means that channel uses channel private keys which
-are not server generated. For this reason server cannot send this
-packet as it does not know the key.
-
-The payload may only be sent with SILC_PACKET_CHANNEL_KEY packet.
-It MUST NOT be sent in any other packet type. The following diagram
-represents the Channel Key Payload.
-
-
-
-
-
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Channel ID Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Channel ID ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Cipher Name Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Cipher Name ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Channel Key Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Channel Key ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 15: Channel Key Payload
-
-
-
-.in 6
-o Channel ID Length (2 bytes) - Indicates the length of the
- Channel ID field in the payload, not including any other
- field.
-
-o Channel ID (variable length) - The Channel ID of the
- channel.
-
-o Cipher Name Length (2 bytes) - Indicates the length of the
- Cipher name field in the payload, not including any other
- field.
-
-o Cipher Name (variable length) - Name of the cipher used
- in the protection of channel traffic. This name is
- initially decided by the creator of the channel but it
- may change during the life time of the channel as well.
-
-o Channel Key Length (2 bytes) - Indicates the length of the
- Channel Key field in the payload, not including any other
- field.
-
-o Channel Key (variable length) - The actual channel key
- material.
-.in 3
-
-
-.ti 0
-2.3.11 Private Message Payload
-
-Private Message Payload is used to send private message between
-two clients. The messages are sent only to the specified user
-and no other user inside SILC network is able to see the message.
-
-The message can be protected by the session key established by the
-SILC Key Exchange Protocol. However, it is also possible to agree
-to use a private key to protect just the private messages. It is
-for example possible to perform Key Agreement between two clients.
-See section 2.3.20 Key Agreement Payload how to perform key
-agreement. See also section 2.3.12 Private Message Key Payload
-for another way of using private keys with private messages. See
-[SILC1] section 4.6 for detailed description for private message
-key generation procedure.
-
-If normal session key is used to protect the message, every server
-between the sender client and the receiving client MUST decrypt the
-packet and always re-encrypt it with the session key of the next
-receiver of the packet. See section Client To Client in [SILC1].
-
-When the private message key is used, and the Private Message Key
-flag was set in the SILC Packet header no server or router en route
-is able to decrypt or re-encrypt the packet. In this case only the
-SILC Packet header is processed by the servers and routers en route.
-Section Client To Client in [SILC1] gives example of this scheme.
-
-This packet use generic Message Payload as Private Message Payload.
-See section 2.3.2.5 for generic Message Payload.
-
-
-.ti 0
-2.3.12 Private Message Key Payload
-
-This payload is OPTIONAL and can be used to send private message
-key between two clients in the network. The packet is secured with
-normal session keys. By default private messages are encrypted
-with session keys, and with this payload it is possible to set
-private key for private message encryption between two clients.
-
-The receiver of this payload SHOULD verify for example from user
-whether user want to receive private message key. Note that there
-are other, more secure ways of exchanging private message keys in
-the SILC network. Instead of sending this payload it is possible to
-negotiate the private message key with SKE protocol using the Key
-Agreement payload directly peer to peer, see section 2.3.20.
-
-This payload may only be sent by client to another client. Server
-MUST NOT send this payload. After sending this payload the sender of
-private messages must set the Private Message Key flag into SILC Packet
-Header.
-
-The payload may only be sent with SILC_PACKET_PRIVATE_MESSAGE_KEY
-packet. It MUST NOT be sent in any other packet type. The following
-diagram represents the Private Message Key Payload.
-
-
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Private Message Key Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Private Message Key ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Cipher Name Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Cipher Name ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| HMAC Name Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ HMAC Name ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 16: Private Message Key Payload
-
-
-
-.in 6
-o Private Message Key Length (2 bytes) - Indicates the length
- of the Private Message Key field in the payload, not including
- any other field.
-
-o Private Message Key (variable length) - The actual private
- message key material.
-
-o Cipher Name Length (2 bytes) - Indicates the length of the
- Cipher Name field in the payload, not including any other
- field.
-
-o Cipher Name (variable length) - Name of the cipher to use
- in the private message encryption. If this field does not
- exist then the default cipher of the SILC protocol is used.
- See the [SILC1] for defined ciphers.
-
-o HMAC Name Length (2 bytes) - Indicates the length of the
- HMAC Name field in the payload, not including any other
- field.
-
-o HMAC Name (variable length) - Name of the HMAC to use
- in the private message MAC computation. If this field does
- not exist then the default HMAC of the SILC protocol is used.
- See the [SILC1] for defined HMACs.
-.in 3
-
-
-.ti 0
-2.3.13 Command Payload
-
-Command Payload is used to send SILC commands from client to server.
-Also server MAY send commands to other servers. The following diagram
-represents the Command Payload.
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Payload Length | SILC Command | Arguments Num |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Command Identifier |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 17: Command Payload
-
-
-.in 6
-o Payload Length (2 bytes) - Length of the entire command
- payload including any command argument payloads associated
- with this payload.
-
-o SILC Command (1 byte) - Indicates the SILC command. This MUST
- be set to non-zero value. If zero (0) value is found in this
- field the packet MUST be discarded.
-
-o Arguments Num (1 byte) - Indicates the number of arguments
- associated with the command. If there are no arguments this
- field is set to zero (0). The arguments MUST follow the
- Command Payload. See section 2.3.2.2 for definition of the
- Argument Payload.
-
-o Command Identifier (2 bytes) - Identifies this command at the
- sender's end. The entity which replies to this command MUST
- set the value found from this field into the Command Payload
- used to send the reply to the sender. This way the sender
- can identify which command reply belongs to which originally
- sent command. What this field includes is implementation
- issue but it is RECOMMENDED that wrapping counter value is
- used in the field.
-.in 3
-
-See [SILC4] for detailed description of different SILC commands,
-their arguments and their reply messages.
-
-
-.ti 0
-2.3.14 Command Reply Payload
-
-Command Reply Payload is used to send replies to the commands. The
-Command Reply Payload is identical to the Command Payload thus see
-the 2.3.13 section for the payload specification.
-
-The entity which sends the reply packet MUST set the Command Identifier
-field in the reply packet's Command Payload to the value it received
-in the original command packet.
-
-See SILC Commands in [SILC4] for detailed description of different
-SILC commands, their arguments and their reply messages.
-
-
-.ti 0
-2.3.15 Connection Auth Request Payload
-
-Client MAY send this payload to server to request the authentication
-method that must be used in authentication protocol. If client knows
-this information beforehand this payload is not necessary to be sent.
-Server performing authentication with another server MAY also send
-this payload to request the authentication method. If the connecting
-server already knows this information this payload is not necessary
-to be sent.
-
-Server receiving this request SHOULD reply with same payload sending
-the mandatory authentication method. Algorithms that may be required
-to be used by the authentication method are the ones already
-established by the SILC Key Exchange protocol. See section Key
-Exchange Start Payload in [SILC3] for detailed information.
-
-The payload may only be sent with SILC_PACKET_CONNECTION_AUTH_REQUEST
-packet. It MUST NOT be sent in any other packet type. The following
-diagram represents the Connection Auth Request Payload.
-
-
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Connection Type | Authentication Method |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 18: Connection Auth Request Payload
-
-
-.in 6
-o Connection Type (2 bytes) - Indicates the type of the
- connection. The following connection types are defined:
-
-
- 1 Client connection
- 2 Server connection
- 3 Router connection
-
- If any other type is found in this field the packet MUST be
- discarded and the authentication MUST be failed.
-
-o Authentication Method (2 bytes) - Indicates the authentication
- method to be used in the authentication protocol. The following
- authentication methods are defined:
-
- 0 NONE (mandatory)
- 1 password (mandatory)
- 2 public key (mandatory)
-
- If any other type is found in this field the packet MUST be
- discarded and the authentication MUST be failed. If this
- payload is sent as request to receive the mandatory
- authentication method this field MUST be set to zero (0),
- indicating that receiver should send the mandatory
- authentication method. The receiver sending this payload
- to the requesting party, MAY also set this field to zero (0)
- to indicate that authentication is not required. In this
- case authentication protocol still MUST be started but
- server is most likely to respond with SILC_PACKET_SUCCESS
- immediately.
-.in 3
-
-
-.ti 0
-2.3.16 New ID Payload
-
-New ID Payload is a multipurpose payload. It is used to send newly
-created ID's from clients and servers. When client connects to server
-and registers itself to the server by sending SILC_PACKET_NEW_CLIENT
-packet, server replies with this packet by sending the created ID for
-the client. Server always creates the ID for the client.
-
-This payload is also used when server tells its router that new client
-has registered to the SILC network. In this case the server sends
-the Client ID of the client to the router. Similarly when router
-distributes information to other routers about the client in the SILC
-network this payload is used.
-
-Also, when server connects to router, router use this payload to inform
-other routers about new server in the SILC network. However, every
-server (or router) creates their own ID's thus the ID distributed by
-this payload is not created by the distributor in this case. Servers
-create their own ID's. Server registers itself to the network by
-sending SILC_PACKET_NEW_SERVER to the router it connected to. The case
-is same when router connects to another router.
-
-This payload MUST NOT be used to send information about new channels.
-New channels are always distributed by sending the dedicated
-SILC_PACKET_NEW_CHANNEL packet. Client MUST NOT send this payload.
-Both client and server (and router) MAY receive this payload.
-
-The packet use generic ID Payload as New ID Payload. See section
-2.3.2.1 for generic ID Payload.
-
-
-.ti 0
-2.3.17 New Client Payload
-
-When client is connected to the server, keys has been exchanged and
-connection has been authenticated, client MUST register itself to the
-server. Client's first packet after key exchange and authentication
-protocols MUST be SILC_PACKET_NEW_CLIENT. This payload tells server all
-the relevant information about the connected user. Server creates a new
-client ID for the client when received this payload and sends it to the
-client in New ID Payload.
-
-This payload sends username and real name of the user on the remote host
-which is connected to the SILC server with SILC client. The server
-creates the client ID according the information sent in this payload.
-The nickname of the user becomes the nickname sent in this payload.
-
-The payload may only be sent with SILC_PACKET_NEW_CLIENT packet. It
-MUST NOT be sent in any other packet type. The following diagram
-represents the New Client Payload.
-
-
-
-
-
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Username Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Username ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Real Name Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Real Name ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 19: New Client Payload
-
-
-.in 6
-o Username Length (2 bytes) - Length of the Username field.
-
-o Username (variable length) - The username of the user on
- the host where connecting to the SILC server.
-
-o Real Name Length (2 bytes) - Length of the Real Name field.
-
-o Real Name (variable length) - The real name of the user
- on the host where connecting to the SILC server.
-.in 3
-
-
-.ti 0
-2.3.18 New Server Payload
-
-This payload is sent by server when it has completed successfully both
-key exchange and connection authentication protocols. The server
-MUST register itself to the SILC Network by sending this payload.
-The first packet after these key exchange and authentication protocols
-is SILC_PACKET_NEW_SERVER packet. The payload includes the Server ID
-of the server that it has created by itself. It also includes a
-name of the server that is associated to the Server ID.
-
-The payload may only be sent with SILC_PACKET_NEW_SERVER packet. It
-MUST NOT be sent in any other packet type. The following diagram
-represents the New Server Payload.
-
-
-
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Server ID Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Server ID Data ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Server Name Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Server Name ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 20: New Server Payload
-
-
-.in 6
-o Server ID Length (2 bytes) - Length of the Server ID Data
- field.
-
-o Server ID Data (variable length) - The encoded Server ID
- data.
-
-o Server Name Length (2 bytes) - Length of the server name
- field.
-
-o Server Name (variable length) - The server name string.
-.in 3
-
-
-.ti 0
-2.3.19 New Channel Payload
-
-Information about newly created channel is broadcasted to all routers
-in the SILC network by sending this packet payload. Channels are
-created by router of the cell. Server never creates channels unless
-it is a standalone server and it does not have router connection,
-in this case server acts as router. Normal server send JOIN command
-to the router (after it has received JOIN command from client) which
-then processes the command and creates the channel. Client MUST NOT
-send this packet. Server MAY send this packet to a router when it is
-announcing its existing channels to the router after it has connected
-to the router.
-
-The packet use generic Channel Payload as New Channel Payload. See
-section 2.3.2.3 for generic Channel Payload. The Mode Mask field in the
-Channel Payload is the mode of the channel.
-
-
-.ti 0
-2.3.20 Key Agreement Payload
-
-This payload is used by clients to request key negotiation between
-another client in the SILC Network. The key agreement protocol used
-is the SKE protocol. The result of the protocol, the secret key
-material, can be used for example as private message key between the
-two clients. This significantly adds security as the clients agree
-about the key without any server interaction. The protocol is executed
-peer to peer. The server and router MUST NOT send this payload.
-
-The sender MAY tell the receiver of this payload the hostname and the
-port where the SKE protocol is running in the sender's end. The
-receiver MAY then initiate the SKE negotiation with the sender. The
-sender MAY also optionally not to include the hostname and the port
-of its SKE protocol. In this case the receiver MAY reply to the
-request by sending the same payload filled with the receiver's hostname
-and the port where the SKE protocol is running. The sender MAY then
-initiate the SKE negotiation with the receiver.
-
-This payload may be sent with SILC_PACKET_KEY_AGREEMENT and
-SILC_PACKET_FTP packet types. It MUST NOT be sent in any other packet
-types. The following diagram represents the Key Agreement Payload.
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Hostname Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Hostname ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Port |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 21: Key Agreement Payload
-
-
-.in 6
-o Hostname Length (2 bytes) - Indicates the length of the
- Hostname field.
-
-o Hostname (variable length) - The hostname or IP address where
- the SKE protocol is running. The sender MAY fill this field
- when sending the payload. If the receiver sends this payload
- as reply to the request it MUST fill this field.
-
-o Port (4 bytes) - The port where the SKE protocol is bound.
- The sender MAY fill this field when sending the payload. If
- the receiver sends this payload as reply to the request it
- MUST fill this field. This is a 32 bit MSB first order value.
-.in 3
-
-
-After the key material has been received from the SKE protocol it is
-processed as the [SILC3] describes. If the key material is used as
-channel private key then the Sending Encryption Key, as defined in
-[SILC3] is used as the channel private key. Other key material must
-be discarded. The [SILC1] in section 4.6 defines the way to use the
-key material if it is intended to be used as private message keys.
-Any other use for the key material is undefined.
-
-
-.ti 0
-2.3.21 Resume Router Payload
-
-See the [SILC1] for Resume Router protocol where this payload is
-used. The payload may only be sent with SILC_PACKET_RESUME_ROUTER
-packet. It MUST NOT be sent in any other packet type. The following
-diagram represents the Resume Router Payload.
-
-
-.in 21
-.nf
- 1
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Type | Session ID |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 22: Resume Router Payload
-
-
-.in 6
-o Type (1 byte) - Indicates the type of the backup resume
- protocol packet. The type values are defined in [SILC1].
-
-o Session ID (1 bytes) - Indicates the session ID for the
- backup resume protocol. The sender of the packet sets this
- value and the receiver MUST set the same value in subsequent
- reply packet.
-.in 3
-
-
-.ti 0
-2.3.22 File Transfer Payload
-
-File Transfer Payload is used to perform file transfer protocol between
-two entities in the network. The actual file transfer protocol is always
-encapsulated inside the SILC Packet. The actual data stream is also sent
-peer to peer outside SILC network.
-
-When an entity, usually a client wishes to perform file transfer protocol
-with another client in the network, they perform Key Agreement protocol
-as described in the section 2.3.20 Key Agreement Payload and in [SILC3],
-inside File Transfer Payload. After the Key Agreement protocol has been
-performed the subsequent packets in the data stream will be protected
-using the new key material. The actual file transfer protocol is also
-initialized in this stage. All file transfer protocol packets are always
-encapsulated in the File Transfer Payload and protected with the
-negotiated key material.
-
-The payload may only be sent with SILC_PACKET_FTP packet. It MUST NOT
-be sent in any other packet type. The following diagram represents the
-File Transfer Payload.
-
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Type | |
-+-+-+-+-+-+-+-+-+ +
-| |
-~ Data ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 23: File Transfer Payload
-
-
-.in 6
-o Type (1 byte) - Indicates the type of the file transfer
- protocol. The following file transfer protocols has been
- defined:
-
- 1 Secure File Transfer Protocol (SFTP) (mandatory)
-
- If zero (0) value or any unsupported file transfer protocol
- type is found in this field the packet MUST be discarded.
- The currently mandatory file transfer protocol is SFTP.
- The SFTP protocol is defined in [SFTP].
-
-o Data (variable length) - Arbitrary file transfer data. The
- contents and encoding of this field is dependent of the usage
- of this payload and the type of the file transfer protocol.
- When this payload is used to perform the Key Agreement
- protocol, this field include the Key Agreement Payload,
- as defined in the section 2.3.20 Key Agreement Payload.
- When this payload is used to send the actual file transfer
- protocol data, the encoding is defined in the corresponding
- file transfer protocol.
-.in 3
-
-
-.ti 0
-2.3.23 Resume Client Payload
-
-This payload is used by client to resume its detached session in the
-SILC Network. A client is able to detach itself from the network by
-sending SILC_COMMAND_DETACH command to its server. The network
-connection to the client is lost but the client remains as valid
-client in the network. The client is able to resume the session back
-by sending this packet and including the old Client ID, and an
-Authentication Payload [SILC1] which the server use to verify with
-the detached client's public key. This also implies that the
-mandatory authentication method is public key authentication.
-
-Server or router that receives this from the client also sends this,
-without the Authentication Payload, to routers in the network so that
-they know the detached client has resumed. Refer to the [SILC1] for
-detailed description how the detaching and resuming procedure is
-performed.
-
-The payload may only be sent with SILC_PACKET_RESUME CLIENT packet. It
-MUST NOT be sent in any other packet type. The following diagram
-represents the Resume Client Payload.
-
-.in 5
-.nf
- 1 2 3
- 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
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| Client ID Length | |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
-| |
-~ Client ID ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| |
-~ Authentication Payload ~
-| |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-.in 3
-
-.ce
-Figure 24: Resume Client Payload
-
-
-.in 6
-o Client ID Length (1 byte) - The length of the Client ID
- field not including any other field.
-
-o Client ID (variable length) - The detached client's Client
- ID. The client that sends this payload must know the Client
- ID.
-
-o Authentication Payload (variable length) - The authentication
- payload that the server will verify with the detached client's
- public key. If the server doesn't know the public key, it must
- retrieve it for example with SILC_COMMAND_GETKEY command.
-.in 3
-
-
-
-.ti 0
-2.4 SILC ID Types
-
-ID's are used in the SILC network to associate different entities.
-The following ID's has been defined to be used in the SILC network.
-
-.in 6
-0 No ID
-
- This is used when other ID type is available at the time.
-
-1 Server ID
-
- Server ID to associate servers. See the format of
- this ID in [SILC1].
-
-2 Client ID
-
- Client ID to associate clients. See the format of
- this ID in [SILC1].
-
-3 Channel ID
-
- Channel ID to associate channels. See the format of
- this ID in [SILC1].
-.in 3
-
-When encoding different IDs into the ID Payload, all fields are always
-in MSB first order. The IP address, port, and/or the random number
-are encoded in the MSB first order.
-
-
-.ti 0
-2.5 Packet Encryption And Decryption
-
-SILC packets are encrypted almost entirely. Only the MAC at the end
-of the packet is never encrypted. The SILC Packet header is the first
-part of a packet to be encrypted and it is always encrypted with the
-key of the next receiver of the packet. The data payload area of the
-packet is always entirely encrypted and it is usually encrypted with
-the next receiver's key. However, there are some special packet types
-and packet payloads that require special encryption process. These
-special cases are described in the next sections. First is described
-the normal packet encryption process.
-
-
-
-.ti 0
-2.5.1 Normal Packet Encryption And Decryption
-
-Normal SILC packets are encrypted with the session key of the next
-receiver of the packet. The entire SILC Packet header and the packet
-data payload is is encrypted with the same key. Padding of the packet
-is also encrypted always with the session key, also in special cases.
-Computed MAC of the packet MUST NOT be encrypted.
-
-Decryption process in these cases are straightforward. The receiver
-of the packet MUST first decrypt the SILC Packet header, or some parts
-of it, usually first 16 bytes of it. Then the receiver checks the
-packet type from the decrypted part of the header and can determine
-how the rest of the packet must be decrypted. If the packet type is
-any of the special cases described in the following sections the packet
-decryption is special. If the packet type is not among those special
-packet types rest of the packet can be decrypted with the same key.
-At this point the receiver is also able to determine the length of the
-packet.
-
-With out a doubt, this sort of decryption processing causes some
-overhead to packet decryption, but never the less, is required.
-
-The MAC of the packet is also verified at this point. The MAC is
-computed from the ciphertext of the packet so it can be verified
-at this stage. The length of the packet need to be known to be able
-to verify the MAC from the ciphertext so the first 16 bytes need to
-be decrypted to determine the packet length. However, the MAC MUST
-be verified from the entire ciphertext.
-
-
-.ti 0
-2.5.2 Channel Message Encryption And Decryption
-
-Channel Messages (Channel Message Payload) are always encrypted with
-the channel specific key. However, the SILC Packet header is not
-encrypted with that key. As in normal case, the header is encrypted
-with the key of the next receiver of the packet. Note that, in this
-case the encrypted data area is not touched at all; it MUST NOT be
-re-encrypted with the session key.
-
-Receiver of a channel message, who ever that is, is REQUIRED to decrypt
-the SILC Packet header to be able to recognize the packet to be as
-channel message. This is same procedure as for normal SILC packets.
-As the receiver founds the packet to be channel message, rest of the
-packet processing is special. Rest of the SILC Packet header is
-decrypted with the same session key along with the padding of the
-packet. After that the packet is protected with the channel specific
-key and thus can be decrypted only if the receiver is the client on
-the channel. See section 2.7 Packet Padding Generation for more
-information about padding on special packets.
-
-If the receiver of the channel message is router which is routing the
-message to another router then it MUST decrypt the Channel Message
-payload too. Between routers (that is, between cells) channel messages
-are protected with session keys shared between the routers. This
-causes another special packet processing for channel messages. If
-the channel message is received from another router then the entire
-packet, including Channel Message payload, MUST be encrypted with the
-session key shared between the routers. In this case the packet
-decryption process is as with normal SILC packets. Hence, if the
-router is sending channel message to another router the Channel
-Message payload MUST have been decrypted and MUST be re-encrypted
-with the session key shared between the another router. In this
-case the packet encryption is as with any normal SILC packet.
-
-It must be noted that this is only when the channel messages are sent
-from router to another router. In all other cases the channel
-message encryption and decryption is as described before. This
-different processing of channel messages with router to router
-connection is because channel keys are cell specific. All cells have
-their own channel keys thus the channel message traveling from one
-cell to another MUST be protected as it would be any normal SILC
-packet.
-
-If the SILC_CMODE_PRIVKEY channel mode has been set for the channel
-then the router cannot decrypt the packet as it does not know the
-private key. In this case the entire packet MUST be encrypted with
-the session key and sent to the router. The router receiving the
-packet MUST check the channel mode and decrypt the packet accordingly.
-
-
-.ti 0
-2.5.3 Private Message Encryption And Decryption
-
-By default, private message in SILC are protected by session keys.
-In this case the private message encryption and decryption process is
-equivalent to normal packet encryption and decryption.
-
-However, private messages MAY be protected with private message key
-which causes the packet to be special packet. The procedure in this
-case is very much alike to channel packets. The actual private message
-is encrypted with the private message key and other parts of the
-packet is encrypted with the session key. See 2.7 Packet Padding
-Generation for more information about padding on special packets.
-
-The difference from channel message processing is that server or router
-en route never decrypts the actual private message, as it does not
-have the key to do that. Thus, when sending packets between router
-the processing is same as in any other case as well; the packet's header
-and padding is protected by the session key and the data area is not
-touched and is not re-encrypted.
-
-The true receiver of the private message is able to decrypt the private
-message as it shares the key with the sender of the message.
-
-
-.ti 0
-2.6 Packet MAC Generation
-
-Data integrity of a packet is protected by including a message
-authentication code (MAC) at the end of the packet. The MAC is computed
-from shared secret MAC key, that is established by the SILC Key Exchange
-protocol, from packet sequence number, and from the encrypted packet
-data. The MAC is always computed after packet is encrypted. This is
-so called Encrypt-Then-MAC order; packet is first encrypted, then MAC
-is computed from the encrypted data.
-
-The MAC is computed from entire packet. Every bit of data in the packet,
-including SILC Packet Header is used in the MAC computing. This way
-the entire packet becomes authenticated.
-
-Hence, packet's MAC generation is as follows:
-
- mac = MAC(key, sequence number | Encrypted SILC packet)
-
-The MAC key is negotiated during the SKE protocol. The sequence number
-is a 32 bit MSB first value starting from zero for first packet and
-increasing for subsequent packets, finally wrapping after 2^32 packets.
-The value is never reset, not even after rekey has been performed.
-However, rekey MUST be performed before the sequence number wraps
-and repeats from zero. Note that the sequence number is incremented only
-when MAC is computed for a packet. If packet is not encrypted and MAC is
-not computed then the sequence number is not incremented. Hence, the
-sequence number is zero for the very first encrypted packet.
-
-See [SILC1] for defined and allowed MAC algorithms.
-
-
-.ti 0
-2.7 Packet Padding Generation
-
-Padding is needed in the packet because the packet is encrypted. It
-always MUST be multiple by eight (8) or multiple by the block size
-of the cipher, which ever is larger. The padding is always encrypted.
-
-For normal packets the padding is added after the SILC Packet Header
-and between the Data Payload area. The padding for normal packets
-may be calculated as follows:
-
-.in 6
-padding_length = 16 - (packet_length mod block_size)
-if (padding_length < 8)
- padding_length += block_size
-.in 3
-
-The `block_size' is the block size of the cipher. The maximum padding
-length is 128 bytes, and minimum is 8 bytes. For example, packets that
-include a passphrase or a password for authentication purposes SHOULD
-pad the packet up to the maximum padding length. The maximum padding
-is calculated as follows:
-
-.in 6
-padding_length = 128 - (packet_length mod block_size)
-.in 3
-
-For special packets the padding calculation is different as special
-packets may be encrypted differently. In these cases the encrypted
-data area MUST already be multiple by the block size thus in this case
-the padding is calculated only for SILC Packet Header, not for any
-other area of the packet. The same algorithm works in this case as
-well, except that the `packet length' is now the SILC Packet Header
-length.
-
-The padding MUST be random data, preferably, generated by
-cryptographically strong random number generator for each packet
-separately.
-
-
-.ti 0
-2.8 Packet Compression
-
-SILC Packets MAY be compressed. In this case the data payload area
-is compressed and all other areas of the packet MUST remain as they
-are. After compression is performed for the data area, the length
-field of Packet Header MUST be set to the compressed length of the
-data.
-
-The compression MUST always be applied before encryption. When
-the packet is received and decrypted the data area MUST be decompressed.
-Note that the true sender of the packet MUST apply the compression and
-the true receiver of the packet MUST apply the decompression. Any
-server or router en route SHOULD NOT decompress the packet.
-
-
-.ti 0
-2.9 Packet Sending
-
-The sender of the packet MUST assemble the SILC Packet Header with
-correct values. It MUST set the Source ID of the header as its own
-ID, unless it is forwarding the packet. It MUST also set the Destination
-ID of the header to the true destination. If the destination is client
-it will be Client ID, if it is server it will be Server ID and if it is
-channel it will be Channel ID.
-
-If the sender wants to compress the packet it MUST apply the
-compression now. Sender MUST also compute the padding as described
-in above sections. Then sender MUST encrypt the packet as has been
-described in above sections according whether the packet is normal
-packet or special packet. Then sender MUST compute the MAC of the
-packet. The computed MAC MUST NOT be encrypted.
-
-
-.ti 0
-2.10 Packet Reception
-
-On packet reception the receiver MUST check that all fields in the
-SILC Packet Header are valid. It MUST check the flags of the
-header and act accordingly. It MUST also check the MAC of the packet
-and if it is to be failed the packet MUST be discarded. Also if the
-header of the packet includes any bad fields the packet MUST be
-discarded.
-
-See above sections on the decryption process of the received packet.
-
-The receiver MUST also check that the ID's in the header are valid
-ID's. Unsupported ID types or malformed ID's MUST cause packet
-rejection. The padding on the reception is always ignored.
-
-The receiver MUST also check the packet type and start parsing the
-packet according to the type. However, note the above sections on
-special packet types and their parsing.
-
-
-.ti 0
-2.11 Packet Routing
-
-Routers are the primary entities in the SILC network that takes care
-of packet routing. However, normal servers routes packets as well, for
-example, when they are routing channel message to the local clients.
-Routing is quite simple as every packet tells the true origin and the
-true destination of the packet.
-
-It is still RECOMMENDED for routers that has several routing connections
-to create route cache for those destinations that has faster route than
-the router's primary route. This information is available for the router
-when other router connects to the router. The connecting party then
-sends all of its locally connected clients, servers and channels. These
-informations helps to create the route cache. Also, when new channels
-are created to a cell its information is broadcasted to all routers
-in the network. Channel ID's are based on router's ID thus it is easy
-to create route cache based on these informations. If faster route for
-destination does not exist in router's route cache the packet MUST be
-routed to the primary route (default route).
-
-However, there are some issues when routing channel messages to group
-of users. Routers are responsible of routing the channel message to
-other routers, local servers and local clients as well. Routers MUST
-send the channel message to only one router in the network, preferably
-to the shortest route to reach the channel users. The message can be
-routed into either upstream or downstream. After the message is sent
-to a router in the network it MUST NOT be sent to any other router in
-either same route or other route. The message MUST NOT be routed to
-the router it came from.
-
-When routing for example private messages they should be routed to the
-shortest route always to reach the destination client as fast as possible.
-
-For server which receives a packet to be routed to its locally connected
-client the server MUST check whether the particular packet type is
-allowed to be routed to the client. Not all packets may be sent by
-some odd entity to client that is indirectly connected to the sender.
-See section 2.3 SILC Packet Types and paragraph about indirectly connected
-entities and sending packets to them. The section mentions the packets
-that may be sent to indirectly connected entities. It is clear that
-server cannot send, for example, disconnect packet to client that is not
-directly connected to the server.
-
-Routers form a ring in the SILC network. However, routers may have other
-direct connections to other routers in the network too. This can cause
-interesting routing problems in the network. Since the network is a ring,
-the packets usually should be routed into clock-wise direction, or if it
-cannot be used then always counter clock-wise (primary route) direction.
-Problems may arise when a faster direct route exists and router is routing
-a channel message. Currently channel messages must be routed either
-in upstream or downstream, they cannot be routed to other direct routes.
-The SILC protocol should have a shortest path discovery protocol, and some
-existing routing protocol, that can handle a ring network with other
-direct routes inside the ring (so called hybrid ring-mesh topology),
-MAY be defined to be used with the SILC protocol. Additional
-specifications MAY be written on the subject to permeate this
-specification.
-
-
-.ti 0
-2.12 Packet Broadcasting
-
-SILC packets MAY be broadcasted in SILC network. However, only router
-server may send or receive broadcast packets. Client and normal server
-MUST NOT send broadcast packets and they MUST ignore broadcast packets
-if they receive them. Broadcast packets are sent by setting Broadcast
-flag to the SILC packet header.
-
-Broadcasting packets means that the packet is sent to all routers in
-the SILC network, except to the router that sent the packet. The router
-receiving broadcast packet MUST send the packet to its primary route.
-The fact that SILC routers may have several router connections can
-cause problems, such as race conditions inside the SILC network, if
-care is not taken when broadcasting packets. Router MUST NOT send
-the broadcast packet to any other route except to its primary route.
-
-If the primary route of the router is the original sender of the packet
-the packet MUST NOT be sent to the primary route. This may happen
-if router has several router connections and some other router uses
-the router as its primary route.
-
-Routers use broadcast packets to broadcast for example information
-about newly registered clients, servers, channels etc. so that all the
-routers may keep these informations up to date.
-
-
-.ti 0
-3 Security Considerations
-
-Security is central to the design of this protocol, and these security
-considerations permeate the specification. Common security considerations
-such as keeping private keys truly private and using adequate lengths for
-symmetric and asymmetric keys must be followed in order to maintain the
-security of this protocol.
-
-
-.ti 0
-4 References
-
-[SILC1] Riikonen, P., "Secure Internet Live Conferencing (SILC),
- Protocol Specification", Internet Draft, May 2002.
-
-[SILC3] Riikonen, P., "SILC Key Exchange and Authentication
- Protocols", Internet Draft, May 2002.
-
-[SILC4] Riikonen, P., "SILC Commands", Internet Draft, May 2002.
-
-[IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
- RFC 1459, May 1993.
-
-[IRC-ARCH] Kalt, C., "Internet Relay Chat: Architecture", RFC 2810,
- April 2000.
-
-[IRC-CHAN] Kalt, C., "Internet Relay Chat: Channel Management", RFC
- 2811, April 2000.
-
-[IRC-CLIENT] Kalt, C., "Internet Relay Chat: Client Protocol", RFC
- 2812, April 2000.
-
-[IRC-SERVER] Kalt, C., "Internet Relay Chat: Server Protocol", RFC
- 2813, April 2000.
-
-[SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
- Internet Draft.
-
-[PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
- November 1998.
-
-[SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
- September 1999.
-
-[PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
- Infrastructure, Certificate and CRL Profile", RFC 2459,
- January 1999.
-
-[Schneier] Schneier, B., "Applied Cryptography Second Edition",
- John Wiley & Sons, New York, NY, 1996.
-
-[Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
- CRC Press 1997.
-
-[OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
- RFC 2412, November 1998.
-
-[ISAKMP] Maughan D., et al, "Internet Security Association and
- Key Management Protocol (ISAKMP)", RFC 2408, November
- 1998.
-
-[IKE] Harkins D., and Carrel D., "The Internet Key Exchange
- (IKE)", RFC 2409, November 1998.
-
-[HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
- Authentication", RFC 2104, February 1997.
-
-[PKCS1] Kalinski, B., and Staddon, J., "PKCS #1 RSA Cryptography
- Specifications, Version 2.0", RFC 2437, October 1998.
-
-[RFC2119] Bradner, S., "Key Words for use in RFCs to Indicate
- Requirement Levels", BCP 14, RFC 2119, March 1997.
-
-[SFTP] Ylonen T., and Lehtinen S., "Secure Shell File Transfer
- Protocol", Internet Draft, March 2001.
-
-[RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO
- 10646", RFC 2279, January 1998.
-
-
-.ti 0
-5 Author's Address
-
-.nf
-Pekka Riikonen
-Snellmaninkatu 34 A 15
-70100 Kuopio
-Finland
-
-EMail: priikone@iki.fi
-
-
-.ti 0
-6 Full Copyright Statement
-
-Copyright (C) The Internet Society (2003). All Rights Reserved.
-
-This document and translations of it may be copied and furnished to
-others, and derivative works that comment on or otherwise explain it
-or assist in its implementation may be prepared, copied, published
-and distributed, in whole or in part, without restriction of any
-kind, provided that the above copyright notice and this paragraph are
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projects / runtime.git / blobdiff