--- /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 XXX
+.ds CH
+.na
+.hy 0
+.in 0
+.nf
+Network Working Group P. Riikonen
+Internet-Draft
+draft-riikonen-presence-attrs-02.txt XXX
+Expires: XXX
+
+.in 3
+
+.ce 2
+User Online Presence and Information Attributes
+<draft-riikonen-presence-attrs-02.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 document defines set of attributes that can represent the online
+user's presence in a network, and to provide general information about
+the user. The purpose is to provide a generic mechanism to share
+online presence and status, and general information about the user
+to be used in several kind of network protocols and applications.
+These attributes could be used by for example chat and conferencing
+protocols (such as Instant Message protocols), network games, and
+other similar network protocols and applications that has online
+users in a network.
+
+
+
+
+
+
+
+.ti 0
+Table of Contents
+
+.nf
+1 Introduction .................................................. 2
+ 1.1 Requirements Terminology .................................. 2
+2 Attributes Concept ............................................ 3
+ 2.1 Requesting Attributes ..................................... 3
+ 2.2 Replying Attributes ....................................... 3
+ 2.3 Attribute Data Types ...................................... 4
+ 2.4 Attribute Payload ......................................... 4
+ 2.5 Attributes ................................................ 5
+3 Security Considerations ....................................... 11
+4 References .................................................... 12
+5 Author's Address .............................................. 13
+
+
+.ti 0
+1. Introduction
+
+This document defines set of attributes that can represent the online
+user's presence in a network, and to provide general information about
+the user. The purpose is to provide a generic mechanism to share
+online presence and status, and general information about the user
+to be used in several kind of network protocols and applications.
+These attributes could be used by for example chat and conferencing
+protocols (such as Instant Message protocols), network games, and
+other similar network protocols and applications that has online
+users in a network.
+
+This document does not define these attributes to be used in any
+specific protocol, but assumes that they can be used generally in
+any kind of online network protocol. Furthermore, the document
+pays attention to special needs of various protocols, such as
+mobile network protocols, which requires the attributes to be
+both robust and compact. The attributes are also considered to be
+easily implementable and for this reason a clear and robust structure
+was chosen for the attributes.
+
+This document is strongly influenced by Wireless Village Initiative
+where similar attributes are defined, and credits for the ideas are
+due there. However, they are defined only in the context of the
+Wireless Village, and the format of the attributes used is not
+suitable for general purpose usage.
+
+
+.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 Attributes Concept
+
+Many network protocols needs a way to transfer and retrieve status
+information about users in a network. For example, many chat and
+conferencing protocols such as IRC, and all Instant Message (IM)
+protocols, such as ICQ has a way to retrieve presence and status
+information about the users in the network. This could be added to
+several other kind of network protocols as well, and for this reason
+a defined mechanism to provide these informations is needed.
+
+The attributes are usually requested by an entity in the network
+from other entity, usually a user or end user's device in the network.
+The recipient then replies to each of the requested attributes and
+sends the reply to the requester.
+
+This document does not define the actual transport for requesting and
+providing the replies to the requests, since this is irrelevant.
+This document defines a payload for requesting, and providing the
+information, but how the payload is transported is not defined in
+this document. In a client-server network model the user requesting
+attributes usually destine the request to a remote user and the
+server relays the attributes to the remote user. It is also possible
+that the concept is not user-to-user, but the server replies to the
+requested attributes on behalf of the user.
+
+
+.ti 0
+2.1 Requesting Attributes
+
+When an entity requests attributes from a user in the network,
+it assembles a list of Attribute Payloads, and sets the requested
+attribute value into the payload. Each requested attribute is a separate
+Attribute Payload and they MUST be appended one after the other. The
+requester need to understand that the recipient may not understand all
+the requested attributes, and may not reply to all of the requested
+attributes. The requester also need to understand that the recipient
+may reply with additional attributes that were not requested.
+
+
+.ti 0
+2.2 Replying Attributes
+
+When en entity receives the Attribute Payloads it parses them one after
+the other. The entity can parse each of the Attribute Payload separately
+since it knows the length of the current attribute; next attribute
+begins after the current attribute ends. The entity then checks the
+requested attribute and SHOULD reply either with valid value or with
+an indication that the attribute is unsupported or unknown. It is
+also possible to reply with additional attributes that were not
+requested.
+
+When replying to the requested attributes the entity assembles a list
+of Attribute Payloads, each including the attribute type and the
+actual attribute data.
+
+
+.ti 0
+2.3 Attribute Data Types
+
+This section defines basic data types that can appear in the attributes
+in this document.
+
+All integer values are stored in the MSB first order. The size of the
+integer is provided separately with the attribute. Integer is
+represented as "integer" in this documentation.
+
+Strings are always UTF-8 [RFC2279] encoded, and include 2 bytes length
+field indicating the length of the string. Hence, when "string" value
+appears in this documentation it is encoded as:
+
+.in 6
+Length Type Value
+2 bytes integer Length of String field
+variable UTF-8 String
+.in 3
+
+If string is not present then the length field includes zero (0)
+value.
+
+Boolean value is represented as "boolean" and its size is 1 byte.
+Value 0x00 indicates false value and value 0x01 indicates true value.
+
+
+.ti 0
+2.4 Attribute Payload
+
+The Attribute Payload is used to request an attribute, and to reply
+to the requested attribute. One payload includes one attribute.
+
+
+.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
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| Attribute | Attr Flags | Attribute Length |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| |
+~ Attribute Data ~
+| |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+.in 3
+
+.ce
+Figure 1: Attribute Payload
+
+
+.in 6
+o Attribute (1 byte) - Indicates the attribute included in this
+ Attribute Payload.
+
+o Attribute Flags (1 byte) - Indicates the flags associated
+ with this attribute. The following flags are defined:
+
+ 0x01 ATTRIBUTE_FLAG_INVALID
+
+ The attribute value in Attribute Data is invalid, or
+ unknown. This may be set to indicate that a requested
+ attribute is not available, its value is unknown, or
+ sender does not understand it.
+
+ 0x02 ATTRIBUTE_FLAG_VALID
+
+ The attribute value is included in the Attribute Data.
+
+ When sending this payload to request attributes this value
+ MUST be set to zero (0) value. When sending a reply to the
+ request this field MUST NOT include a zero (0) value.
+
+o Attribute Length (2 bytes) - Indicates the length of the
+ Attribute Data field, not including any other field.
+
+o Attribute Data (variable length) - The Attribute Data.
+ The contents of this field is attribute specific, defined
+ subsequently.
+.in 3
+
+
+.ti 0
+2.5 Attributes
+
+The following values can appear in the Attribute field in the
+Attribute Payload to indicate the content of the attribute. The
+format of the attribute data is represented as length, type and
+value. Example:
+
+.in 6
+Length Type Value
+2 bytes integer Some integer value
+variable string Some string
+1 byte boolean Boolean value
+.in 3
+
+When sending multiple Attribute Payloads it is possible to include
+multiple same attributes in the packet.
+
+
+.in 6
+0 ATTRIBUTE_NONE
+
+ This attribute is reserved and it is never sent.
+
+
+1 ATTRIBUTE_USER_INFO
+
+ This attribute includes general information about the user, their
+ name and contact information. The content of this attribute is
+ a VCard version 3.0 as defined in RFC 2426 [RFC2426] and RFC 2425
+ [RFC2425]. Note that some of the information that VCard provides
+ can be also provided in the means of providing other attributes.
+ The rationale for this is that the VCard does not provide all the
+ information, or with the required precision that may be desired in
+ some applications. It is therefore RECOMMENDED that this attribute
+ would be used to provide only basic and constant user information,
+ such as name and contact information, but not online status
+ information.
+
+ Length Type Value
+ variable VCard Basic user information
+
+
+2 ATTRIBUTE_SERVICE
+
+ This attribute indicates a service in the Internet that the user
+ is currently using or has logged in. It also shows when the user
+ started using the service, and how long user has been idle in the
+ service. The value of this attribute is as follows:
+
+ Length Type Value
+ 4 bytes integer Service Port (IANA specified)
+ variable string Service Address
+ 1 byte boolean Online status. If this is set to
+ 0x01 (true) it means the user is online
+ in the service. Set to 0x00 (false) when
+ out of reach.
+ variable string Signon date and time, UTC date, format as
+ in ISO 8601
+ 4 bytes integer Idle time
+
+
+3 ATTRIBUTE_STATUS_MOOD
+
+ This attribute indicates the mood of the user. It can indicate
+ whether the user is eager to participate in the network. The
+ value of this attribute is as follows:
+
+ Length Type Value
+ 4 bytes integer Mood mask (values ORed together)
+
+ The following mood values are defined:
+
+ 0x00000000 MOOD_NORMAL No specific mood, normal mood
+ 0x00000001 MOOD_HAPPY The user feels happy
+ 0x00000002 MOOD_SAD The user feels sad
+ 0x00000004 MOOD_ANGRY The user feels angry
+ 0x00000008 MOOD_JEALOUS The user feels jealous
+ 0x00000010 MOOD_ASHAMED The user feels ashamed
+ 0x00000020 MOOD_INVINCIBLE The user feels invincible
+ 0x00000040 MOOD_INLOVE The user feels being in love
+ 0x00000080 MOOD_SLEEPY The user feels sleepy
+ 0x00000100 MOOD_BORED The user feels bored
+ 0x00000200 MOOD_EXCITED The user feels excited
+ 0x00000400 MOOD_ANXIOUS The user feels anxious
+
+
+4 ATTRIBUTE_STATUS_FREETEXT
+
+ This attribute includes the user's online status free text. It
+ can provide personal status as a text message. The contents of
+ this attribute is a UTF-8 encoded free text string.
+
+ Length Type Value
+ variable string Free text status string
+
+
+5 ATTRIBUTE_STATUS_MESSAGE
+
+ This attribute includes the user's online status message. It
+ could provide for example a multi media message showing the status
+ of the user. The contents of this attribute is a MIME object,
+ which can be used to provide for example video, audio, image or
+ other similar status message. It could also provide a reference
+ to the message, for example an URL address.
+
+ Length Type Value
+ variable MIME Status message as MIME object
+
+
+6 ATTRIBUTE_PREFERRED_LANGUAGE
+
+ This attribute indicates the preferred language to be used when
+ communicating. The encoding of this attribute is as follows:
+
+ Length Type Value
+ variable string ISO 639-2/T three letter code
+
+
+7 ATTRIBUTE_PREFERRED_CONTACT
+
+ This attribute indicates the preferred contact methods. It can
+ indicate the method the user prefers when contacting. The value
+ of this attribute is as follows:
+
+ Length Type Value
+ 4 bytes integer Contact mask (values ORed together)
+
+ The following contact methods are defined:
+
+ 0x00000000 CONTACT_NONE No specific preferred contact method
+ 0x00000001 CONTACT_EMAIL Email is preferred
+ 0x00000002 CONTACT_CALL Phone call is preferred
+ 0x00000004 CONTACT_PAGE Paging is preferred
+ 0x00000008 CONTACT_SMS SMS is preferred
+ 0x00000010 CONTACT_MMS MMS is preferred
+ 0x00000020 CONTACT_CHAT Chatting is preferred
+
+
+8 ATTRIBUTE_TIMEZONE
+
+ This attribute can be used to provide the current local time for
+ the user. The contents of this attribute is a UTF-8 encoded
+ string and the format of the string is UTC time zone defined
+ in the ISO 8601.
+
+ Length Type Value
+ variable string UTC date, format as in ISO 8601
+
+ Note that ATTRIBUTE_USER_INFO may also provide this information.
+ However it is RECOMMENDED that this attribute is used when
+ current time zone information is provided.
+
+
+9 ATTRIBUTE_GEOLOCATION
+
+ This attribute can be used to provide measured global location of
+ the user. How this information is gathered is out of scope of
+ this document. The attribute can provide latitude and longitude
+ lateral positions, but also a vertical position. A parameter
+ describing the accuracy of the information can also be provided.
+
+ Length Type Value
+ variable string Longitude (ex. 31 17 14.321W)
+ variable string Latitude (ex. 12 11 21.2N)
+ variable string Altitude
+ variable string Accuracy in meters
+
+ Note that ATTRIBUTE_USER_INFO may also provide this information,
+ however it does not have the vertical position, or the accuracy
+ parameter. It is RECOMMENDED that this attribute is used when
+ providing current global position information.
+
+
+10 ATTRIBUTE_DEVICE_INFO
+
+ This attribute includes information about the user's device.
+ The encoding of this attribute is as follows:
+
+ Length Type Value
+ 4 bytes integer Device type
+ variable string Name of the device manufacturer
+ variable string Device version
+ variable string Device model
+ variable string Device language (ISO 639-2/T)
+
+ The following Device types are defined:
+
+ 0 DEVICE_COMPUTER Device is a computer
+ 1 DEVICE_MOBILE_PHONE Device is a mobile phone
+ 2 DEVICE_PDA Device is a PDA
+ 3 DEVICE_TERMINAL Device is a terminal
+
+
+11 ATTRIBUTE_EXTENSION
+
+ This attribute indicates that the attribute value is vendor,
+ application or service specific attribute extension. This field
+ MUST include a MIME object, which is the extension value. This
+ document does not specify any explicit MIME objects for this
+ attribute.
+
+ Length Type Value
+ variable MIME Attribute extension as MIME object
+
+
+12 ATTRIBUTE_USER_PUBLIC_KEY
+
+ This attribute includes the user's public key or certificate.
+ As the public key and certificate format depends on which sort
+ of algorithm or certificate encoding user is using we need to
+ define a mechanism to differentiate the public key types from
+ each other. This document specifies the most common public keys
+ and certificates. This attribute can be used to deliver the
+ user's public key, and it MUST be present if also the
+ ATTRIBUTE_USER_DIGITAL_SIGNATURE is present. Note that the
+ recipient of this attribute SHOULD verify the public key from
+ a third party, for example from Certification Authority. If
+ there are more than one ATTRIBUTE_USER_PUBLIC_KEY attributes set
+ and ATTRIBUTE_USER_DIGITAL_SIGNATURE is also set, the digital
+ signature SHOULD be verifiable with the first set public key.
+
+ Length Type Value
+ variable string Public key/certificate type
+ variable data Public key/certificate data
+
+ The following public key/certificate types are defined:
+
+ ssh-rsa SSH RSA public key [SSH-TRANS]
+ ssh-dss SSH DSS public key [SSH-TRANS]
+ silc-rsa SILC RSA public key [SILC1]
+ silc-dss SILC DSS public key [SILC1]
+ pgp-sign-rsa OpenPGP RSA certificate [RFC2440]
+ pgp-sign-dss OpenPGP DSS certificate [RFC2440]
+ x509v3-sign-rsa X.509 Version 3 RSA certificate [RFC2459]
+ x509v3-sign-dss X.509 Version 3 DSS certificate [RFC2459]
+
+ Most of these public key/certificate types are equivalent to
+ the types specified for SSH protocol [SSH-TRANS] and are expected
+ to be officially assigned by IANA.
+
+ The encoding of the public key/certificate data in the attribute
+ is done in the manner defined in their respective definitions.
+
+ Note that these public keys are intended for signing. Some
+ certificates may have a key usage restrictions and same key cannot
+ be used for both encryption and signing. Therefore, the name
+ of the certificate type indicates if they are intended for
+ signing only.
+
+
+13 ATTRIBUTE_SERVER_PUBLIC_KEY
+
+ This attribute includes a third party server or authority public
+ key or CA certificate and MUST be present if the attribute
+ ATTRIBUTE_SERVER_DIGITAL_SIGNATURE is also present. The format
+ for this attribute is identical to the ATTRIBUTE_USER_PUBLIC_KEY
+ attribute. If there are more than one ATTRIBUTE_SERVER_PUBLIC_KEY
+ attributes set and ATTRIBUTE_SERVER_DIGITAL_SIGNATURE is also set,
+ the digital signature SHOULD be verifiable with the first set public
+ key.
+
+
+14 ATTRIBUTE_USER_DIGITAL_SIGNATURE
+
+ This attribute value includes digital signature of all Attribute
+ Payloads except this attribute. This signature can be provided by
+ the user. This attribute SHOULD be last attribute provided in the
+ reply so that it is easier for the receiver to compute the signature
+ data to be verified. The format and encoding of this attribute
+ depends on the public key or certificate used to produce the
+ signature. See the ATTRIBUTE_USER_PUBLIC_KEY for all public keys
+ and certificates that can be used to produce a signature.
+
+ Length Type Value
+ variable data Digital signature data
+
+ The encodings are as follows per public key/certificate type:
+
+ ssh-rsa and ssh-dss Defined in [SSH-TRANS]
+ silc-rsa and silc-dss Defined in [SILC1]
+ pgp-sign-rsa and pgp-sign-dss Defined in [RFC2440]
+ x509v3-sign-rsa and x509v3-sign-dss Defined in [PKCS7]
+
+ The procedure producing the signature and encoding it are done
+ in the manner defined in their respective definitions, see the
+ provided references. Also the hash function used with the
+ signature procedure is defined by the public key/certificate type.
+
+
+15 ATTRIBUTE_SERVER_DIGITAL_SIGNATURE
+
+ This attribute value includes digital signature of all Attribute
+ Payloads except this attribute, but including the attribute
+ ATTRIBUTE_USER_DIGITAL_SIGNATURE. This signature can be provided
+ by a third party server or an authority which has verified the
+ information provided by the user. How it verifies this information
+ is out of scope of this document, however it may base its
+ information to a previous registration information and current
+ online status of the user in a service. This attribute SHOULD be
+ last when provided, so that it is easier for the receiver to
+ compute the signature data to be verified. The format for this
+ attribute is identical to the ATTRIBUTE_USER_DIGITAL_SIGNATURE
+ attribute.
+.in 3
+
+
+.ti 0
+3 Security Considerations
+
+The use of these attributes dictates whether the attributes need to
+be secured or not. However, as the attributes are considered to provide
+accurate status information about specific user, it is suggested that
+the attributes would be secured. The attributes should be digitally
+signed whenever it is possible. Attributes can also be encrypted
+if it is provided by the protocol using the attributes. A third party,
+like a server in the network, could also verify the information and provide
+digital signature in case the information is accurate.
+
+Even though the attributes would be digitally signed by the sender of
+the attributes, the information contained in the attribute may still
+be incorrect. The third party server should not apply digital signature
+unless it can verify every attribute. The receiver of the attributes
+should also not trust that the information in fact is correct.
+
+However, it is possible that the context where these attributes are used
+the attributes are provided by a party that can provide the accurate
+information. For example a server in the network could reply to the
+attributes on behalf of the actual user for some of the attributes.
+
+
+.ti 0
+4 References
+
+[RFC2119] Bradner, S., "Key Words for use in RFCs to Indicate
+ Requirement Levels", BCP 14, RFC 2119, March 1997.
+
+[RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO
+ 10646", RFC 2279, January 1998.
+
+[RFC2425] Howes, T., et al, "A MIME Content-Type for Directory
+ Information", RFC 2425, September 1998.
+
+[RFC2426] Dawson, F., et al, "vCard MIME Directory Profile",
+ RFC 2426, September 1998.
+
+[SILC1] Riikonen, P., "Secure Internet Live Conferencing (SILC),
+ Protocol Specification", Internet Draft, May 2002.
+
+[RFC2440] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
+ November 1998.
+
+[RFC2459] Housley, R., et al, "Internet X.509 Public Key
+ Infrastructure, Certificate and CRL Profile", RFC 2459,
+ January 1999.
+
+[SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
+ Internet Draft.
+
+[PKCS7] Kalinski, B., "PKCS #7: Cryptographic Message Syntax,
+ Version 1.5", RFC 2315, March 1998.
+
+
+
+
+.ti 0
+5 Author's Address
+
+Pekka Riikonen
+Snellmaninkatu 34 A 15
+70100 Kuopio
+Finland
+
+EMail: priikone@iki.fi
+
+This Internet-Draft expires XXX
--- /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 XXX
+.ds CH
+.na
+.hy 0
+.in 0
+.nf
+Network Working Group P. Riikonen
+Internet-Draft
+draft-riikonen-silc-commands-05.txt XXX
+Expires: XXX
+
+.in 3
+
+.ce 2
+SILC Commands
+<draft-riikonen-silc-commands-05.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 the commands used in the Secure Internet Live
+Conferencing (SILC) protocol, specified in the Secure Internet Live
+Conferencing, Protocol Specification Internet Draft [SILC1]. The
+SILC Commands are very important part of the SILC protocol. Usually
+the commands are used by SILC clients to manage the SILC session, but
+also SILC servers may use the commands. This memo specifies detailed
+command messages and command reply messages.
+
+
+
+
+
+
+
+
+.ti 0
+Table of Contents
+
+.nf
+1 Introduction .................................................. 2
+ 1.1 Requirements Terminology .................................. 2
+2 SILC Commands ................................................. 2
+ 2.1 SILC Commands Syntax ...................................... 4
+ 2.2 SILC Command Argument Idioms .............................. 4
+ 2.3 SILC Commands List ........................................ 4
+ 2.4 SILC Command Status Payload ............................... 42
+3 SILC Status Types ............................................. 43
+4 Security Considerations ....................................... 49
+5 References .................................................... 49
+6 Author's Address .............................................. 51
+Appendix A ...................................................... 51
+
+
+.ti 0
+1. Introduction
+
+This document describes the commands used in the Secure Internet Live
+Conferencing (SILC) protocol, specified in the Secure Internet Live
+Conferencing, Protocol Specification Internet Draft [SILC1]. This
+document specifies detailed command messages and command reply messages.
+
+Commands are very important part on SILC network especially for client
+which uses commands to operate on the SILC network. Commands are used
+to set nickname, join to channel, change modes and many other things.
+
+See the [SILC1] for the requirements and the restrictions for the usage
+of the SILC commands. The [SILC2] defines the command packet type and
+the Command Payload which is actually used to deliver the commands and
+command reply messages.
+
+
+.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 Commands
+
+.ti 0
+2.1 SILC Commands Syntax
+
+This section briefly describes the syntax of the command notions
+in this document. Every field in command is separated from each
+other by whitespaces (` ') indicating that each field is independent
+argument and each argument MUST have own Command Argument Payload.
+The number of maximum arguments are defined with each command
+separately. The Command Argument Payload is described in [SILC2].
+
+Every command defines specific number for each argument. Currently,
+they are defined in ascending order; first argument has number one
+(1), second has number two (2) and so on. This number is set into the
+Argument Type field in the Command Argument Payload. This makes it
+possible to send the arguments in free order as the number MUST be
+used to identify the type of the argument. This makes is it also
+possible to have multiple optional arguments in commands and in
+command replies. The number of argument is marked in parentheses
+before the actual argument.
+
+
+
+.in 6
+Example: Arguments: (1) <nickname> (2) <username@host>
+.in 3
+
+
+Every command replies with Status Payload. This payload tells the
+sender of the command whether the command was completed successfully or
+whether there was an error. If error occurred the payload includes the
+error type. In the next section the Status Payload is not described
+as it is common to all commands and has been described here. Commands
+MAY reply with other arguments as well. These arguments are command
+specific and are described in the next section.
+
+Example command:
+.in 6
+
+EXAMPLE_COMMAND
+
+.in 8
+Max Arguments: 3
+ Arguments: (1) <nickname>[@<server>] (2) <message>
+ (3) [<count>]
+
+The command has maximum of 3 arguments. However, only first
+and second arguments are mandatory.
+
+First argument <nickname> is mandatory but may have optional
+<nickname@server> format as well. Second argument is mandatory
+<message> argument. Third argument is optional <count> argument.
+
+The numbers in parentheses are the argument specific numbers
+that specify the type of the argument in Command Argument Payload.
+The receiver always knows that, say, argument number two (2) is
+<message> argument, regardless of the ordering of the arguments in
+the Command Payload.
+
+Reply messages to the command:
+
+Max Arguments: 4
+ Arguments: (1) <Status Payload> (2) [<channel list>]
+ (3) <idle time> (4) [<away message>]
+
+This command may reply with maximum of 4 arguments. However,
+only the first and third arguments are mandatory. The numbers
+in the parentheses have the same meaning as in the upper
+command sending specification.
+
+Every command reply with <Status Payload>, it is mandatory
+argument for all command replies and for this reason it is not
+described in the command reply descriptions.
+
+
+
+Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_NO_SUCH_NICK
+
+Every command reply also defines set of status message that it
+may return inside the <Status Payload>. All status messages
+are defined in the section 2.3 SILC Command Status Payload
+The status messages defined with the command are recommendations.
+It is possible to return other status messages not listed with
+the command reply definition.
+.in 3
+
+
+.ti 0
+2.2 SILC Command Argument Idioms
+
+All commands that has an ID as argument (for example <Client ID>) are
+actually ID Payloads, defined in [SILC2] that includes the type of the
+ID, length of the ID and the actual ID data. This way variable length
+ID's can be sent as arguments.
+
+All passphrases that may be sent in commands as arguments MUST be
+UTF-8 [RFC2279] encoded.
+
+All public keys and certificates that are sent as arguments are actually
+Public Key Payloads [SILC2]. This way it is possible to send different
+kind of public keys and certificate types as arguments.
+
+
+.ti 0
+2.3 SILC Commands List
+
+This section lists all SILC commands, however, it is expected that a
+implementation and especially client implementation has many more
+commands that has only local affect. These commands are official
+SILC commands that has both client and server sides and cannot be
+characterized as local commands.
+
+List of all defined commands in SILC follows.
+
+.in 0
+ 0 SILC_COMMAND_NONE
+
+ None. This is reserved command and MUST NOT be sent.
+
+
+ 1 SILC_COMMAND_WHOIS
+
+ Max Arguments: 256
+ Arguments: (1) [<nickname>[@<server>]] (2) [<count>]
+ (3) [<Requested Attributes>] (4) [<Client ID>]
+ (n) [...]
+
+ Whois command is used to query various information about specific
+ user. The user may be requested by their nickname and server name.
+ The query may find multiple matching users as there are no unique
+ nicknames in the SILC. The <count> option may be given to narrow
+ down the number of accepted results. If this is not defined there
+ are no limit of accepted results. The query may also be narrowed
+ down by defining the server name of the nickname. The <count> is
+ 32 bit MSB first order integer.
+
+ It is also possible to search the user by Client ID. If the
+ <Client ID> is provided server MUST use it as the search value
+ instead of the <nickname>. One of the arguments MUST be given.
+ It is also possible to define multiple Client ID's to search
+ multiple users sending only one WHOIS command. In this case the
+ Client ID's are appended as normal arguments.
+
+ To prevent miss-use of this command wildcards in the nickname
+ or in the server name are not permitted. It is not allowed
+ to request all users on some server. The WHOIS requests MUST
+ be based on explicit nickname request.
+
+ The WHOIS request MUST be always sent to the router by server
+ so that all users are searched. However, the server still MUST
+ search its locally connected clients. The router MUST send
+ this command to the server which owns the requested client, if
+ the router is unable to provide all mandatory information about
+ the client. That server MUST reply to the command. Server MUST
+ NOT send whois replies to the client until it has received the
+ reply from its router.
+
+ The <Requested Attributes> is defined in [ATTRS] and can be used
+ to request various information about the client. See Appendix A
+ for definition of using these attributes in SILC.
+
+ Reply messages to the command:
+
+ Max Arguments: 11
+ Arguments: (1) <Status Payload> (2) <Client ID>
+ (3) <nickname>[@<server>] (4) <username@host>
+ (5) <real name> (6) [<Channel Payload
+ list>]
+ (7) [<user mode>] (8) [<idle time>]
+ (9) [<fingerprint>] (10) <channel user
+ mode list>
+ (11) [<Attributes>]
+
+
+ This command may reply with several command reply messages to
+ form a list of results. In this case the status payload will
+ include STATUS_LIST_START status in the first reply and
+ STATUS_LIST_END in the last reply to indicate the end of the
+ list. If there are only one reply the status is set to normal
+ STATUS_OK. If multiple Client IDs was requested then each found
+ and unfound client must cause successful or error reply,
+ respectively.
+
+ The command replies include the Client ID of the nickname,
+ nickname and server name, user name and host name and user's real
+ name. Client should process these replies only after the last
+ reply has been received with the STATUS_LIST_END status. If the
+ <count> option were defined in the query there will be only
+ <count> many replies from the server.
+
+ The server returns the list of channels if the client has
+ joined channels. In this case the list is list of Channel
+ Payloads. The Mode Mask in the Channel Payload is the channel's
+ mode. The list is encoded by adding the Channel Payloads one
+ after the other. Private and secret channels MUST NOT be sent,
+ except if the sender of this command is on those channels, or
+ the sender is server. The <channel user mode list> MUST also
+ be sent if client is joined channels. This list includes 32 bit
+ MSB first order values one after the other and each indicate
+ the user's mode on a channel. The order of these values MUST
+ be same as the channel order in the <Channel Payload list>.
+
+ The server also returns client's user mode, idle time, and the
+ fingerprint of the client's public key. The <fingerprint> is the
+ binary hash digest of the public key. The fingerprint MUST NOT
+ be sent if the server has not verified the proof of possession of
+ the corresponding private key. Server can do this during the
+ SILC Key Exchange protocol. The <fingerprint> is SHA1 digest.
+
+ The <Attributes> is the reply to the <Requested Attributes>.
+ See the Appendix A for more information.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_LIST_START
+ SILC_STATUS_LIST_END
+ SILC_STATUS_ERR_NO_SUCH_NICK
+ SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
+ SILC_STATUS_ERR_WILDCARDS
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+
+
+ 2 SILC_COMMAND_WHOWAS
+
+ Max Arguments: 2
+ Arguments: (1) <nickname>[@<server>] (2) [<count>]
+
+ Whowas. This command is used to query history information about
+ specific user. The user may be requested by their nickname and
+ server name. The query may find multiple matching users as there
+ are no unique nicknames in the SILC. The <count> option may be
+ given to narrow down the number of accepted results. If this
+ is not defined there are no limit of accepted results. The query
+ may also be narrowed down by defining the server name of the
+ nickname. The <count> is 32 bit MSB first order integer.
+
+ To prevent miss-use of this command wildcards in the nickname
+ or in the server name are not permitted. The WHOWAS requests MUST
+ be based on specific nickname request.
+
+ The WHOWAS request MUST be always sent to the router by server
+ so that all users are searched. However, the server still must
+ search its locally connected clients.
+
+ Reply messages to the command:
+
+ Max Arguments: 5
+ Arguments: (1) <Status Payload> (2) <Client ID>
+ (3) <nickname>[@<server>] (4) <username@host>
+ (5) [<real name>]
+
+ This command may reply with several command reply messages to form
+ a list of results. In this case the status payload will include
+ STATUS_LIST_START status in the first reply and STATUS_LIST_END in
+ the last reply to indicate the end of the list. If there are only
+ one reply the status is set to normal STATUS_OK.
+
+ The command replies with nickname and user name and host name.
+ Every server MUST keep history for some period of time of its
+ locally connected clients.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_LIST_START
+ SILC_STATUS_LIST_END
+ SILC_STATUS_ERR_NO_SUCH_NICK
+ SILC_STATUS_ERR_WILDCARDS
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+
+
+ 3 SILC_COMMAND_IDENTIFY
+
+ Max Arguments: 256
+ Arguments: (1) [<nickname>[@<server>]] (2) [<server name>]
+ (3) [<channel name>] (4) [<count>]
+ (5) [<ID Payload>] (n) [...]
+
+ Identify command is used to query information about an entity by
+ the entity's name or ID. This command can be used to query
+ information about clients, servers and channels.
+
+ The query may find multiple matching entities. The <count> option
+ may be given to narrow down the number of accepted results. If
+ this is not defined there are no limit of accepted results. The
+ <count> is 32 bit MSB first order integer.
+
+ It is also possible to search the entity by its ID. If the
+ <ID Payload> is provided server must use it as the search value
+ instead of the entity's name. One of the arguments must be given.
+ It is also possible to define multiple ID Payloads to search
+ multiple entities sending only one IDENTIFY command. In this case
+ the ID Payloads are appended as normal arguments. The type of the
+ entity is defined by the type of the ID Payload.
+
+ To prevent miss-use of this command wildcards in the names are
+ not permitted. It is not allowed to request for example all users
+ on server.
+
+ Implementations may not want to give interface access to this
+ command as it is hardly a command that would be used by an end
+ user. However, it must be implemented as it is most likely used
+ with private message sending.
+
+ The IDENTIFY command MUST be always sent to the router by server
+ so that all users are searched. However, server MUST still search
+ its locally connected clients.
+
+ Reply messages to the command:
+
+ Max Arguments: 4
+ Arguments: (1) <Status Payload> (2) <ID Payload>
+ (3) [<entity's name>] (4) [<info>]
+
+ This command may reply with several command reply messages to form
+ a list of results. In this case the status payload will include
+ STATUS_LIST_START status in the first reply and STATUS_LIST_END in
+ the last reply to indicate the end of the list. If there are only
+ one reply the status is set to normal STATUS_OK. If multiple Client
+ IDs was requested then each found and unfound client must cause
+ successful or error reply, respectively.
+
+ When querying clients the <entity's name> must include the client's
+ nickname in the following format: nickname[@server]. The
+ <info> must include the client's username and host in the following
+ format: username@host.
+
+ When querying servers the <entity's name> must include the server's
+ full name. The <info> may be omitted.
+
+ When querying channels the <entity's name> must include the
+ channel's name. The <info> may be omitted.
+
+ If the <count> option were defined in the query there will be only
+ <count> many replies from the server.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_LIST_START
+ SILC_STATUS_LIST_END
+ SILC_STATUS_ERR_NO_SUCH_NICK
+ SILC_STATUS_ERR_NO_SUCH_SERVER
+ SILC_STATUS_ERR_NO_SUCH_CHANNEL
+ SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
+ SILC_STATUS_ERR_NO_SUCH_SERVER_ID
+ SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
+ SILC_STATUS_ERR_WILDCARDS
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+
+
+ 4 SILC_COMMAND_NICK
+
+ Max Arguments: 1
+ Arguments: (1) <nickname>
+
+ Set/change nickname. This command is used to set nickname for
+ user. Nickname MUST NOT include any spaces (` '), non-printable
+ characters, commas (`,') and any wildcard characters.
+
+ When nickname is changed new Client ID is generated. Server MUST
+ distribute SILC_NOTIFY_TYPE_NICK_CHANGE to local clients on the
+ channels (if any) the client is joined on. Then it MUST send
+ SILC_NOTIFY_TYPE_NICK_CHANGE notify to its primary route to
+ notify about nickname and Client ID change.
+
+ Reply messages to the command:
+
+ Max Arguments: 3
+ Arguments: (1) <Status Payload> (2) <New ID Payload>
+ (3) <nickname>
+
+ This command replies always with <New ID Payload> that is
+ generated by the server every time user changes their nickname.
+ Client receiving this payload MUST start using the received
+ Client ID as its current valid Client ID. The New ID Payload
+ is described in [SILC2]. The <nickname> is the user's new
+ nickname.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_WILDCARDS
+ SILC_STATUS_ERR_NICKNAME_IN_USE
+ SILC_STATUS_ERR_BAD_NICKNAME
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+
+
+ 5 SILC_COMMAND_LIST
+
+ Max Arguments: 1
+ Arguments: (1) [<Channel ID>]
+
+ The list command is used to list channels and their topics on the
+ current server. If the <Channel ID> parameter is used, only the
+ status of that channel is displayed. Secret channels are not
+ listed at all. Private channels are listed with status indicating
+ that the channel is private. Router MAY reply with all channels
+ it knows about.
+
+ Reply messages to the command:
+
+ Max Arguments: 5
+ Arguments: (1) <Status Payload> (2) <Channel ID>
+ (3) <channel> (4) [<topic>]
+ (5) [<user count>]
+
+ This command may reply with several command reply messages to form
+ a list of results. In this case the status payload will include
+ STATUS_LIST_START status in the first reply and STATUS_LIST_END in
+ the last reply to indicate the end of the list. If there are only
+ one reply the status is set to normal STATUS_OK.
+
+ This command replies with Channel ID, name and the topic of the
+ channel. If the channel is private channel the <topic> SHOULD
+ include the "*private*" string.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_LIST_START
+ SILC_STATUS_LIST_END
+ SILC_STATUS_ERR_WILDCARDS
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
+ SILC_STATUS_ERR_NO_CHANNEL_ID
+ SILC_STATUS_ERR_NO_SUCH_SERVER
+
+
+ 6 SILC_COMMAND_TOPIC
+
+ Max Arguments: 2
+ Arguments: (1) <Channel ID> (2) [<topic>]
+
+ This command is used to change or view the topic of a channel.
+ The topic for channel <Channel ID> is returned if there is no
+ <topic> given. If the <topic> parameter is present, the topic
+ for that channel will be changed, if the channel modes permit
+ this action.
+
+ After setting the topic the server MUST send the notify type
+ SILC_NOTIFY_TYPE_TOPIC_SET to its primary router and then to
+ the channel which topic was changed.
+
+ Reply messages to the command:
+
+ Max Arguments: 2
+ Arguments: (1) <Status Payload> (2) <Channel ID>
+ (3) [<topic>]
+
+ The command may reply with the topic of the channel if it is
+ set.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_ON_CHANNEL
+ SILC_STATUS_ERR_WILDCARDS
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_NO_SUCH_CHANNEL
+ SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
+ SILC_STATUS_ERR_NO_CHANNEL_ID
+ SILC_STATUS_ERR_BAD_CHANNEL_ID
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NO_CHANNEL_PRIV
+
+
+ 7 SILC_COMMAND_INVITE
+
+ Max Arguments: 4
+ Arguments: (1) <Channel ID> (2) [<Client ID>]
+ (3) [<add | del>] (4) [<invite list>]
+
+ This command can be used to invite other clients to join to a
+ channel, and to manage the channel's invite list. The <Client
+ ID> argument is the target client's ID that is being invited.
+ The <Channel ID> is the Channel ID of the requested channel.
+ The sender of this command MUST be on the channel. The server
+ MUST also send the notify type SILC_NOTIFY_TYPE_INVITE to its
+ primary router and then to the client indicated by the <Client
+ ID>.
+
+ 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.
+ It may include a string for matching clients, public key of a
+ client or Client ID of a client. The <invite list> format is
+ as follows:
+
+ 2 bytes - Number of arguments in the list
+ variable length - Argument Payloads
+
+ The following Argument Types has been defined for invite list
+ Argument Payloads:
+
+ 0x01 - Argument is an invite string of following format:
+
+ [<nickname>[@<server>]!][<username>]@[<hostname or IP/MASK>]
+
+ The <hostname> may also be in format of IP/MASK to indicate
+ a network.
+
+ 0x02 - Argument is the public key of a client
+ 0x03 - Argument is the Client ID of a client
+
+ If unknown type value is received or there is invalid amount of
+ Argument Payloads present in the list, the command MUST be
+ discarded. When argument that is to be deleted from the invite
+ list does not exist in the list the argument is ignored.
+
+ When adding to or removing from the invite list the server MUST
+ send the notify type SILC_NOTIFY_TYPE_INVITE to its primary router.
+ The client which executes this command MUST have at least channel
+ operator privileges to be able to add to or remove from the invite
+ list. The wildcards MAY be used with this command. When this
+ command is used to invite explicit client with <Client ID> the
+ ID MUST be added to the invite list by the server.
+
+ When this command is given with only <Channel ID> argument then
+ the command merely returns the invite list of the channel. This
+ command MUST fail if the requested channel does not exist, the
+ requested <Client ID> is already on the channel or if the channel
+ is invite only channel and the caller of this command does not
+ have at least channel operator privileges on the channel.
+
+ Reply messages to the command:
+
+ Max Arguments: 3
+ Arguments: (1) <Status Payload> (2) <Channel ID>
+ (3) [<invite list>]
+
+ This command replies with the invite list of the channel if it
+ exists.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
+ SILC_STATUS_ERR_NO_CLIENT_ID
+ SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
+ SILC_STATUS_ERR_NO_CHANNEL_ID
+ SILC_STATUS_ERR_NOT_ON_CHANNEL
+ SILC_STATUS_ERR_USER_ON_CHANNEL
+ SILC_STATUS_ERR_NO_CHANNEL_PRIV
+ SILC_STATUS_ERR_RESOURCE_LIMIT
+
+
+ 8 SILC_COMMAND_QUIT
+
+ Max Arguments: 1
+ Arguments: (1) [<quit message>]
+
+ This command is used by client to end SILC session. The server
+ must close the connection to a client which sends this command.
+ if <quit message> is given it will be sent to other clients on
+ channel if the client is on channel when quitting.
+
+ Reply messages to the command:
+
+ This command does not reply anything.
+
+
+ 9 SILC_COMMAND_KILL
+
+ Max Arguments: 3
+ Arguments: (1) <Client ID> (2) [<comment>]
+ (3) [<auth payload>]
+
+ This command can be used by SILC operators to remove a client from
+ SILC network. It also can be used by a normal client to remove
+ its own client from network by providing correct authentication
+ data.
+
+ Router operator killing a client:
+
+ The removing has temporary effects and client may reconnect to
+ SILC network. The <Client ID> is the client to be removed from SILC.
+ The <comment> argument may be provided to give to the removed client
+ some information why it was removed from the network. The killer
+ MUST have SILC operator privileges.
+
+ When killing a client the router MUST first send notify type
+ SILC_NOTIFY_TYPE_KILLED to all channels the client has joined.
+ The packet MUST NOT be sent to the killed client on the channels.
+ Then, the router MUST send the same notify type to its primary
+ router. Finally, the router MUST send the same notify type
+ directly to the client which was killed. The killed client MUST
+ also be removed from the invite lists of joined channels if it
+ is explicitly added in the invite lists.
+
+ Normal client killing by authentication:
+
+ When normal client executes this command the <Client ID> is the
+ destination client to be removed from the network. The client
+ MUST provide the <auth payload> which includes a digital signature
+ that MUST be verified with the public key of the client indicated
+ by <Client ID>. The <Client ID> MUST be local client to the server.
+ If the signature verification is successful the server sends
+ SILC_NOTIFY_TYPE_SIGNOFF to network and to the destination client.
+ The SILC_NOTIFY_TYPE_KILLED MUST NOT be used in this case. If the
+ verification fails the destination client remains in network.
+ The hash function used in <auth payload> computing is SHA1.
+
+ Reply messages to the command:
+
+ Max Arguments: 1
+ Arguments: (1) <Status Payload>
+
+ This command replies only with Status Payload.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_WILDCARDS
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
+ SILC_STATUS_ERR_NO_CLIENT_ID
+ SILC_STATUS_ERR_NO_ROUTER_PRIV
+
+
+ 10 SILC_COMMAND_INFO
+
+ Max Arguments: 2
+ Arguments: (1) [<server>] (2) [<Server ID>]
+
+ This command is used to fetch various information about a server.
+ If <server> argument is specified the command MUST be sent to
+ the requested server.
+
+ If the <Server ID> is specified the server information if fetched
+ by the provided Server ID. One of the arguments must always be
+ present.
+
+ Reply messages to the command:
+
+ Max Arguments: 4
+ Arguments: (1) <Status Payload> (2) <Server ID>
+ (3) <server name> (4) <string>
+
+ This command replies with the Server ID of the server and a
+ string which tells the information about the server.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_WILDCARDS
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NO_SUCH_SERVER
+ SILC_STATUS_ERR_NO_SUCH_SERVER_ID
+ SILC_STATUS_ERR_NO_SERVER_ID
+
+
+ 11 SILC_COMMAND_STATS
+
+ Max Arguments: 1
+ Arguments: (1) <Server ID>
+
+ This command is used to fetch various statistical information
+ from the server indicated by <Server ID>, which is the ID of
+ server where sender is connected to. Server receiving this
+ command MAY also send this further to its router for fetching
+ other cell and network wide statistics to accompany the reply.
+
+ Reply messages to the command:
+
+ Max Arguments: 3
+ Arguments: (1) <Status Payload> (2) <Server ID>
+ (3) [<statistics structure>]
+
+ This command replies with the Server ID of the server and
+ optional statistics structure which includes 32 bit MSB first
+ ordered integer values to represent various statistical
+ information. The structure is as follows:
+
+ starttime - time when server was started
+ uptime - uptime of the server
+ my clients - number of locally connected clients
+ my channels - number of locally created channels
+ my server ops - number of local server operators
+ my router ops - number of local router operators
+ cell clients - number of clients in local cell
+ cell channels - number of channels in local cell
+ cell servers - number of servers in local cell
+ clients - number of client in SILC network
+ channels - number of channels in SILC network
+ servers - number of servers in SILC network
+ routers - number of routers in SILC network
+ server ops - number of server operators in SILC network
+ router ops - number of router operators in SILC network
+
+ If some value is unknown it is set to zero (0) value. The
+ "starttime" is the start time of the server, and is seconds
+ since Epoch (POSIX.1). The "uptime" is time difference of
+ current time and "starttime" in the server, and is seconds
+ in value.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NO_SUCH_SERVER_ID
+ SILC_STATUS_ERR_NO_SUCH_SERVER
+ SILC_STATUS_ERR_NO_SERVER_ID
+
+
+ 12 SILC_COMMAND_PING
+
+ Max Arguments: 1
+ Arguments: (1) <Server ID>
+
+ This command is used by client and server to test the communication
+ channel to its server if one suspects that the communication is not
+ working correctly. The <Server ID> is the ID of the server the
+ sender is connected to.
+
+ Reply messages to the command:
+
+ Max Arguments: 1
+ Arguments: (1) <Status Payload>
+
+ This command replies only with Status Payload. Server returns
+ SILC_STATUS_OK in Status Payload if pinging was successful.
+
+
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NO_SERVER_ID
+ SILC_STATUS_ERR_NO_SUCH_SERVER
+ SILC_STATUS_ERR_NOT_REGISTERED
+
+
+ 13 SILC_COMMAND_OPER
+
+ Max Arguments: 2
+ Arguments: (1) <username> (2) <authentication payload>
+
+ This command is used by normal client to obtain server operator
+ privileges on some server or router. Note that router operator
+ has router privileges that supersedes the server operator
+ privileges and this does not obtain those privileges. Client
+ MUST use SILCOPER command to obtain router level privileges.
+
+ The <username> is the username set in the server configurations
+ as operator. The <authentication payload> is the data that the
+ client is authenticated against. It may be passphrase prompted
+ for user on client's screen or it may be public key authentication
+ based on digital signatures. The public key used to verify the
+ signature should be locally saved in the server, and server should
+ not use public key received during the SKE to verify this signature.
+
+ After changing the mode the server MUST send the notify type
+ SILC_NOTIFY_TYPE_UMODE_CHANGE to its primary router.
+
+ Reply messages to the command:
+
+ Max Arguments: 1
+ Arguments: (1) <Status Payload>
+
+ This command replies only with Status Payload.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_AUTH_FAILED
+
+
+ 14 SILC_COMMAND_JOIN
+
+ Max Arguments: 6
+ Arguments: (1) <channel> (2) <Client ID>
+ (3) [<passphrase>] (4) [<cipher>]
+ (5) [<hmac>] (6) [<founder auth>]
+
+ Join to channel/create new channel. This command is used to
+ join to a channel. If the channel does not exist the channel is
+ created. If server is normal server this command MUST be sent
+ to router which will create the channel. The channel MAY be
+ protected with passphrase. If this is the case the passphrase
+ MUST be sent along the join command.
+
+ The name of the <channel> MUST NOT include any spaces (` '),
+ non-printable characters, commas (`,') or any wildcard characters.
+
+ The second argument <Client ID> is the Client ID of the client
+ which is joining to the client. When client sends this command
+ to the server the <Client ID> MUST be the client's own ID.
+
+ Cipher to be used to secure the traffic on the channel MAY be
+ requested by sending the name of the requested <cipher>. This
+ is used only if the channel does not exist and is created. If
+ the channel already exists the cipher set previously for the
+ channel will be used to secure the traffic. The computed MACs
+ of the channel message are produced by the default HMAC or by
+ the <hmac> provided for the command.
+
+ The <founder auth> is Authentication Payload providing the
+ authentication for gaining founder privileges on the channel
+ when joining the channel. The client may provide this if it
+ knows that it is the founder of the channel and that the
+ SILC_CMODE_FOUNDER_AUTH mode is set on the channel. The server
+ MUST verify whether the client is able to gain the founder
+ privileges the same way as the client had given the
+ SILC_COMMAND_CUMODE command to gain founder privileges. The
+ client is still able to join the channel even if the founder
+ privileges could not be gained. The hash function used with
+ the <founder payload> MUST be sha1.
+
+ The server MUST check whether the user is allowed to join to
+ the requested channel. Various modes set to the channel affect
+ the ability of the user to join the channel. These conditions
+ are:
+
+ o The user MUST be invited to the channel if the channel
+ is invite-only channel.
+
+ o The Client ID/nickname/username/host name/public key
+ MUST NOT match any active bans.
+
+ o The correct passphrase MUST be provided if passphrase
+ is set to the channel.
+
+ o The user count limit, if set, MUST NOT be reached.
+
+ If the client provided correct <founder auth> payload it can
+ override these conditions, except the condition for the passphrase.
+ The correct passphrase MUST be provided even if <founder auth>
+ payload is provided.
+
+ Reply messages to the command:
+
+ Max Arguments: 15
+ Arguments: (1) <Status Payload> (2) <channel>
+ (3) <Channel ID> (4) <Client ID>
+ (5) <channel mode mask> (6) <created>
+ (7) [<Channel Key Payload>] (8) [<ban list>]
+ (9) [<invite list>] (10) [<topic>]
+ (11) [<hmac>] (12) <list count>
+ (13) <Client ID list> (14) <client mode list>
+ (15) [<founder pubkey>]
+
+ This command replies with the channel name requested by the
+ client, channel ID of the channel and topic of the channel
+ if it exists. The <Client ID> is the Client ID which was joined
+ to the channel. It also replies with the channel mode mask
+ which tells all the modes set on the channel. If the
+ channel is created the mode mask is zero (0). If ban mask
+ and/or invite list is set they are sent as well.
+
+ The <list count>, <Client ID list> and <client mode list> are
+ the clients currently on the channel and their modes on the
+ channel. The <Client ID list> is formed by adding the ID Payloads
+ one after the other. The <client mode list> is formed by adding
+ 32 bit MSB first order values one after the other. The <founder
+ pubkey> is the public key (or certificate) of the channel founder.
+
+ Client receives the channel key in the reply message as well
+ inside <Channel Key Payload>.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_WILDCARDS
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_BAD_PASSWORD
+ SILC_STATUS_ERR_CHANNEL_IS_FULL
+ SILC_STATUS_ERR_NOT_INVITED
+ SILC_STATUS_ERR_BANNED_FROM_CHANNEL
+ SILC_STATUS_ERR_BAD_CHANNEL
+ SILC_STATUS_ERR_USER_ON_CHANNEL
+
+
+ 15 SILC_COMMAND_MOTD
+
+ Max Arguments: 1
+ Arguments: (1) <server>
+
+ This command is used to query the Message of the Day of the server.
+
+ Reply messages to the command:
+
+ Max Arguments: 3
+ Arguments: (1) <Status Payload> (2) <Server ID>
+ (3) [<motd>]
+
+ This command replies with the motd message if it exists.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NO_SUCH_SERVER
+
+
+ 16 SILC_COMMAND_UMODE
+
+ Max Arguments: 2
+ Arguments: (1) <Client ID> (2) [<client mode mask>]
+
+ This command is used by client to set/unset modes for itself.
+ However, there are some modes that the client MUST NOT set itself,
+ but they will be set by server. However, client MAY unset any
+ mode. Modes may be masked together ORing them thus having
+ several modes set. Client MUST keep its client mode mask
+ locally so that the mode setting/unsetting would work without
+ problems. Client may change only its own modes.
+
+ After changing the mode server MUST send the notify type
+ SILC_NOTIFY_TYPE_UMODE_CHANGE to its primary router.
+
+ The following client modes are defined:
+
+ 0x00000000 SILC_UMODE_NONE
+
+ No specific mode for client. This is the initial
+ setting when new client is created. The client is
+ normal client and is present in the network.
+
+
+ 0x00000001 SILC_UMODE_SERVER_OPERATOR
+
+ Marks the user as server operator. Client MUST NOT
+ set this mode itself. Server sets this mode to the
+ client when client attains the server operator
+ privileges by SILC_COMMAND_OPER command. Client
+ MAY unset the mode itself.
+
+
+ 0x00000002 SILC_UMODE_ROUTER_OPERATOR
+
+ Marks the user as router (SILC) operator. Client
+ MUST NOT set this mode itself. Router sets this mode
+ to the client when client attains the router operator
+ privileges by SILC_COMMAND_SILCOPER command. Client
+ MAY unset the mode itself.
+
+
+ 0x00000004 SILC_UMODE_GONE
+
+ Marks that the user is not currently present in the
+ SILC Network. Client MAY set and unset this mode.
+
+
+ 0x00000008 SILC_UMODE_INDISPOSED
+
+ Marks that the user is currently indisposed and may
+ not be able to receive any messages, and that user may
+ not be present in the network. Client MAY set and
+ unset this mode.
+
+
+ 0x00000010 SILC_UMODE_BUSY
+
+ Marks that the user is currently busy and may not
+ want to receive any messages, and that user may not
+ be present in the network. Client MAY set and unset
+ this mode.
+
+
+ 0x00000020 SILC_UMODE_PAGE
+
+ User is not currently present or is unable to receive
+ messages, and prefers to be paged in some mechanism
+ if the user needs to be reached. Client MAY set and
+ unset this mode.
+
+
+ 0x00000040 SILC_UMODE_HYPER
+
+ Marks that the user is hyper active and is eager to
+ receive and send messages. Client MAY set and unset
+ this mode.
+
+
+ 0x00000080 SILC_UMODE_ROBOT
+
+ Marks that the client is actually a robot program.
+ Client MAY set and unset this mode.
+
+
+ 0x00000100 SILC_UMODE_ANONYMOUS
+
+ Marks that the client is anonymous client. Server
+ that specifically is designed for anonymous services
+ can set and unset this mode. Client MUST NOT set or
+ unset this mode itself. A client with this mode set
+ would have the username and the hostname information
+ scrambled by the server which set this mode.
+
+
+ 0x00000200 SILC_UMODE_BLOCK_PRIVMSG
+
+ Marks that the client wishes to block private
+ messages sent to the client, unless the Private
+ Message Key flag is set in the SILC packet header.
+ If this mode is set server MUST NOT deliver private
+ messages to the client without the Private Message
+ Key flag being set. The Private Message Key flag set
+ indicates that the private message is protected with
+ a key shared between the sender and the recipient.
+
+ A separate service could provide additional filtering
+ features for accepting private messages from certain
+ sender. However, this document does not specify such
+ service.
+
+ The client MAY set and unset this mode.
+
+
+ 0x00000400 SILC_UMODE_DETACHED
+
+ Marks that the client is detached from the SILC network.
+ This means that the actual network connection to the
+ client is lost but the client entry is still valid. The
+ detached client can be resumed at a later time. This
+ mode MUST NOT be set by client. It can only be set when
+ client has issued command SILC_COMMAND_DETACH. The server
+ sets this mode. This mode cannot be unset with this
+ command. It is unset when the client is resuming back to
+ the network and SILC_PACKET_RESUME_CLIENT packet is
+ received.
+
+ This flag MUST NOT be used to determine whether a packet
+ can be sent to the client or not. Only the server that
+ had the original client connection can make the decision
+ by knowing that the network connection is not active.
+ In this case the default case is to discard the packet.
+
+
+ 0x00000800 SILC_UMODE_REJECT_WATCHING
+
+ Marks that the client rejects that it could be watched
+ by someone else. If this mode is set notifications about
+ this client is not send, even if someone is watching the
+ same nickname this client has. Client MAY set and unset
+ this mode. Any changes for this client MUST NOT be
+ notified to any watcher when this mode is set.
+
+ A separate service could provide additional filtering
+ features for rejecting and accepting the watching from
+ certain users. However, this document does not specify
+ such service.
+
+
+ 0x00001000 SILC_UMODE_BLOCK_INVITE
+
+ Marks that the client wishes to block incoming invite
+ notifications. Client MAY set and unset this mode.
+ When set server does not deliver invite notifications
+ to the client. Note that this mode may make it harder
+ to join invite-only channels.
+
+ If the <client mode mask> was not provided this command merely
+ returns the mode mask to the client.
+
+
+ Reply messages to the command:
+
+ Max Arguments: 2
+ Arguments: (1) <Status Payload> (2) <client mode mask>
+
+ This command replies with the changed client mode mask that
+ the client MUST to keep locally.
+
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
+ SILC_STATUS_ERR_BAD_CLIENT_ID
+ SILC_STATUS_ERR_NOT_YOU
+ SILC_STATUS_ERR_PERM_DENIED
+ SILC_STATUS_ERR_UNKNOWN_MODE
+ SILC_STATUS_ERR_NO_CLIENT_ID
+
+
+ 17 SILC_COMMAND_CMODE
+
+ Max Arguments: 8
+ Arguments: (1) <Channel ID> (2) [<channel mode mask>]
+ (3) [<user limit>] (4) [<passphrase>]
+ (5) [<cipher>] (6) [<hmac>]
+ (7) [<auth payload>] (8) [<founder pubkey>]
+
+ This command is used by client to set or change channel flags on
+ a channel. Channel has several modes that set various properties
+ of a channel. Modes may be masked together by ORing them thus
+ having several modes set. The <Channel ID> is the ID of the
+ target channel. The client changing channel mode MUST be on
+ the same channel and posses sufficient privileges to be able to
+ change the mode.
+
+ When the mode is changed SILC_NOTIFY_TYPE_CMODE_CHANGE notify
+ type MUST be distributed to the channel.
+
+ The following channel modes are defined:
+
+ 0x00000000 SILC_CMODE_NONE
+
+ No specific mode on channel. This is the default when
+ channel is created. This means that channel is just plain
+ normal channel.
+
+
+ 0x00000001 SILC_CMODE_PRIVATE
+
+ Channel is private channel. Private channels are shown
+ in the channel list listed with SILC_COMMAND_LIST command
+ with indication that the channel is private. Also,
+ client on private channel will no be detected to be on
+ the channel as the channel is not shown in the client's
+ currently joined channel list. Channel founder and
+ channel operator MAY set/unset this mode.
+
+ Typical implementation would use [+|-]p on user interface
+ to set/unset this mode.
+
+
+ 0x00000002 SILC_CMODE_SECRET
+
+ Channel is secret channel. Secret channels are not shown
+ in the list listed with SILC_COMMAND_LIST command. Secret
+ channels can be considered to be invisible channels.
+ Channel founder and channel operator MAY set/unset this
+ mode.
+
+ Typical implementation would use [+|-]s on user interface
+ to set/unset this mode.
+
+
+ 0x00000004 SILC_CMODE_PRIVKEY
+
+ Channel uses private channel key to protect the traffic
+ on the channel. When this mode is set the client will be
+ responsible to set the key it wants to use to encrypt and
+ decrypt the traffic on channel. Server generated channel
+ keys are not used at all. This mode provides additional
+ security as clients on channel may agree to use private
+ channel key that even servers do not know. Naturally,
+ this requires that every client on the channel knows
+ the key before hand (it is considered to be pre-shared-
+ key). The key material SHOULD be processed as stated
+ in the [SILC3] in the section Processing the Key Material.
+
+ As it is local setting it is possible to have several
+ private channel keys on one channel. In this case several
+ clients can talk on same channel but only those clients
+ that share the key with the message sender will be able
+ to hear the talking. Client SHOULD NOT display those
+ message for the end user that it is not able to decrypt
+ when this mode is set.
+
+ Only channel founder MAY set/unset this mode. If this
+ mode is unset the server will distribute new channel
+ key to all clients on the channel which will be used
+ thereafter.
+
+ Typical implementation would use [+|-]k on user interface
+ to set/unset this mode.
+
+
+ 0x00000008 SILC_CMODE_INVITE
+
+ Channel is invite only channel. Client may join to this
+ channel only if it is invited to the channel. Channel
+ founder and channel operator MAY set/unset this mode.
+
+ Typical implementation would use [+|-]i on user interface
+ to set/unset this mode.
+
+
+ 0x00000010 SILC_CMODE_TOPIC
+
+ The topic of the channel may only be set by client that
+ is channel founder or channel operator. Normal clients
+ on channel will not be able to set topic when this mode
+ is set. Channel founder and channel operator MAY set/
+ unset this mode.
+
+ Typical implementation would use [+|-]t on user interface
+ to set/unset this mode.
+
+
+ 0x00000020 SILC_CMODE_ULIMIT
+
+ User limit has been set to the channel. New clients
+ may not join to the channel when the limit set is
+ reached. Channel founder and channel operator MAY set/
+ unset the limit. The <user limit> argument is the
+ number of limited users.
+
+ Typical implementation would use [+|-]l on user interface
+ to set/unset this mode.
+
+
+ 0x00000040 SILC_CMODE_PASSPHRASE
+
+ Passphrase has been set to the channel. Client may
+ join to the channel only if it is able to provide the
+ correct passphrase. Setting passphrases to channel
+ is entirely safe as all commands are protected in the
+ SILC network. Only channel founder MAY set/unset
+ the passphrase. The <passphrase> argument is the
+ set passphrase.
+
+ Typical implementation would use [+|-]a on user interface
+ to set/unset this mode.
+
+
+ 0x00000080 SILC_CMODE_CIPHER
+
+ Sets specific cipher to be used to protect channel
+ traffic. The <cipher> argument is the requested cipher.
+ When set or unset the server must re-generate new
+ channel key. Only channel founder MAY set the cipher of
+ the channel. When unset the new key is generated using
+ default cipher for the channel.
+
+ Typical implementation would use [+|-]c on user interface
+ to set/unset this mode.
+
+
+ 0x00000100 SILC_CMODE_HMAC
+
+ Sets specific hmac to be used to compute the MACs of the
+ channel message. The <hmac> argument is the requested hmac.
+ Only channel founder may set the hmac of the channel.
+
+ Typical implementation would use [+|-]h on user interface
+ to set/unset this mode.
+
+
+ 0x00000200 SILC_CMODE_FOUNDER_AUTH
+
+ Channel founder may set this mode to be able to regain
+ channel founder rights even if the client leaves the
+ channel. The <auth payload> is the Authentication Payload
+ consisting of the public key authentication method and the
+ digital signature for that method. The passphrase or NONE
+ authentication methods MUST NOT be accepted.
+
+ The server does not save <auth payload> but MUST verify it.
+ The public key used to verify the payload is the <founder
+ pubkey> if present, or the public key of the client sending
+ this command. If <founder pubkey> is present also that
+ public key MUST be saved as founder's public key. This
+ mode may be set only if the <auth payload> was verified
+ successfully. The hash function used with the <auth
+ payload> MUST be sha1.
+
+ The public key of the founder is sent in the
+ SILC_NOTIFY_TYPE_CMODE_CHANGE notify type so that other
+ routers and servers in the network may save the public key.
+ This way the founder can reclaim the founder rights back
+ to the channel from any server in the network. The founder
+ rights can be regained by the SILC_CUMODE_FOUNDER channel
+ user mode, or during joining procedure with the command
+ SILC_COMMAND_JOIN.
+
+ If this mode is already set but the <founder pubkey> is
+ different the new key will replace the old founder key and
+ the new key is distributed in the network with the
+ SILC_NOTIFY_TYPE_CMODE_CHANGE notify. Only the original
+ founder may set this mode multiple times and the client
+ MUST have SILC_CUMODE_FOUNDER mode on the channel.
+
+ When this channel mode is set the channel also becomes
+ permanent. If all clients leave the channel while this
+ mode is set the channel MUST NOT be destroyed. The founder
+ can reclaim the founder mode back on these empty channels
+ at any time. Implementations MAY limit the number of how
+ many channels a user can own and how long they remain
+ persistent.
+
+ Typical implementation would use [+|-]f on user interface
+ to set/unset this mode.
+
+
+ 0x00000400 SILC_CMODE_SILENCE_USERS
+
+ Channel founder may set this mode to silence normal users
+ on the channel. Users with operator privileges are not
+ affected by this mode. Messages sent by normal users
+ are dropped by servers when this mode is set. This mode
+ can be used to moderate the channel. Only channel founder
+ may set/unset this mode.
+
+
+ 0x00000800 SILC_CMODE_SILENCE_OPERS
+
+ Channel founder may set this mode to silence operators
+ on the channel. When used with SILC_CMODE_SILENCE_USERS
+ mode this can be used to set the channel in state where only
+ the founder of the channel may send messages to the channel.
+ Messages sent by operators are dropped by servers when this
+ mode is set. Only channel founder may set/unset this mode.
+
+
+ To make the mode system work, client MUST keep the channel mode
+ mask locally so that the mode setting and unsetting would work
+ without problems. The client receives the initial channel mode
+ mask when it joins to the channel. When the mode changes on
+ channel the server MUST distribute the changed channel mode mask
+ to all clients on the channel by sending the notify type
+ SILC_NOTIFY_TYPE_CMODE_CHANGE. The notify type MUST also be sent
+ to the server's primary router. If the <channel mode mask> was
+ not provided this command merely returns the mode mask to the
+ client.
+
+ Reply messages to the command:
+
+ Max Arguments: 4
+ Arguments: (1) <Status Payload> (2) <Channel ID>
+ (3) <channel mode mask> (4) [<founder pubkey>]
+
+ This command replies with the changed channel mode mask that
+ client MUST keep locally. It may also return the channel
+ founder's public key if it is set.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ON_CHANNEL
+ SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
+ SILC_STATUS_ERR_BAD_CHANNEL_ID
+ SILC_STATUS_ERR_NO_CHANNEL_ID
+ SILC_STATUS_ERR_NO_CHANNEL_PRIV
+ SILC_STATUS_ERR_NO_CHANNEL_FOPRIV
+ SILC_STATUS_ERR_UNKNOWN_MODE
+ SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
+ SILC_STATUS_ERR_AUTH_FAILED
+
+
+ 18 SILC_COMMAND_CUMODE
+
+ Max Arguments: 4
+ Arguments: (1) <Channel ID> (2) <mode mask>
+ (3) <Client ID> (4) [<auth payload>]
+
+ This command is used by client to change channel user modes on
+ channel. Users on channel may have some special modes and this
+ command is used by channel operators to set or change these modes.
+ The <Channel ID> is the ID of the target channel. The <mode mask>
+ is OR'ed mask of modes. The <Client ID> is the target client.
+ The client changing channel user modes MUST be on the same channel
+ as the target client and posses sufficient privileges to be able to
+ change the mode.
+
+ When the mode is changed SILC_NOTIFY_TYPE_CUMODE_CHANGE notify
+ type is distributed to the channel.
+
+ The following channel modes are defined:
+
+ 0x00000000 SILC_CUMODE_NONE
+
+ No specific mode. This is the normal situation for client.
+ Also, this is the mode set when removing all modes from
+ the target client.
+
+
+ 0x00000001 SILC_CUMODE_FOUNDER
+
+ The client is channel founder of the channel. Usually this
+ mode is set only by the server when the channel was created.
+ However, if the SILC_CMODE_FOUNDER_AUTH channel mode has
+ been set, the client can claim channel founder privileges
+ by providing the <auth payload> that the server will use
+ to authenticate the client. The public key that server will
+ use to verify the <auth payload> MUST be the same public key
+ that was saved when the SILC_CMODE_FOUNDER_AUTH channel
+ mode was set. The client MAY remove this mode at any time.
+
+
+ 0x00000002 SILC_CUMODE_OPERATOR
+
+ Sets channel operator privileges on the channel for a
+ client on the channel. Channel founder and channel operator
+ MAY set/unset this mode. The client MAY remove this mode
+ at any time.
+
+
+ 0x00000004 SILC_CUMODE_BLOCK_MESSAGES
+
+ Marks that the client wishes not to receive any channel
+ messages sent for the channel. Client MAY set and unset
+ this mode to itself. Client MUST NOT set it to anyone else.
+ When this mode is set server MUST NOT deliver channel
+ messages to this client. Other packets such as channel
+ key packets are still sent to the client.
+
+ A separate service could provide additional filtering
+ features for accepting channel messages from certain
+ sender. However, this document does not specify such
+ service.
+
+
+ 0x00000008 SILC_CUMODE_BLOCK_MESSAGES_USERS
+
+ Marks that the client wishes not to receive any channel
+ messages sent from normal users. Only messages sent by
+ channel founder or channel operator is accepted. Client
+ MAY set and unset this mode to itself. Client MUST NOT
+ set it to anyone else. When this mode is set server MUST
+ NOT deliver channel messages that are sent by normal users
+ to this client.
+
+ A separate service could provide additional filtering
+ features for accepting channel messages from certain
+ sender. However, this document does not specify such
+ service.
+
+
+ 0x00000010 SILC_CUMODE_BLOCK_MESSAGES_ROBOTS
+
+ Marks that the client wishes not to receive any channel
+ messages sent from robots. Messages sent by users with
+ the SILC_UMODE_ROBOT user mode set are not delivered.
+ Client MAY set and unset this mode to itself. Client MUST
+ NOT set it to anyone else. When this mode is set server
+ MUST NOT deliver channel messages that are sent by robots
+ to this client.
+
+
+ 0x00000020 SILC_CUMODE_QUIET
+
+ Marks that the client cannot talk on the channel. This
+ mode can be set by channel operator or channel founder to
+ some other user that is not operator or founder. The
+ target client MUST NOT unset this mode. When this mode
+ is set the server MUST drop messages sent by this client
+ to the channel.
+
+
+ Reply messages to the command:
+
+ Max Arguments: 4
+ Arguments: (1) <Status Payload> (2) <channel user mode mask>
+ (3) <Channel ID> (4) <Client ID>
+
+ This command replies with the changed channel user mode mask that
+ client MUST keep locally. The <Channel ID> is the specified
+ channel. The <Client ID> is the target client.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ON_CHANNEL
+ SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
+ SILC_STATUS_ERR_BAD_CHANNEL_ID
+ SILC_STATUS_ERR_NO_CHANNEL_ID
+ SILC_STATUS_ERR_NO_CHANNEL_PRIV
+ SILC_STATUS_ERR_NO_CHANNEL_FOPRIV
+ SILC_STATUS_ERR_UNKNOWN_MODE
+ SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
+ SILC_STATUS_ERR_AUTH_FAILED
+
+
+ 19 SILC_COMMAND_KICK
+
+ Max Arguments: 3
+ Arguments: (1) <Channel ID> (2) <Client ID>
+ (3) [<comment>]
+
+ This command is used by channel operators to remove a client from
+ channel. The <channel> argument is the channel the client to be
+ removed is on currently. Note that the "kicker" must be on the same
+ channel. If <comment> is provided it will be sent to the removed
+ client.
+
+ After kicking the client the server MUST send the notify type
+ SILC_NOTIFY_TYPE_KICKED to the channel and to its primary router.
+ The kicked client MUST be removed from the invite list of the
+ channel if it is explicitly added in the list. The channel key
+ MUST also be re-generated after kicking, unless the
+ SILC_CMODE_PRIVKEY mode is set.
+
+ Reply messages to the command:
+
+ Max Arguments: 1
+ Arguments: (1) <Status Payload>
+
+ This command replies only with Status Payload.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NO_SUCH_CHANNEL
+ SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
+ SILC_STATUS_ERR_NO_CHANNEL_PRIV
+ SILC_STATUS_ERR_NO_CLIENT_ID
+
+
+
+
+ 20 SILC_COMMAND_BAN
+
+ Max Arguments: 3
+ Arguments: (1) <Channel ID> (2) [<add | del>]
+ (3) [<ban list>]
+
+ This command is used to manage the ban list of the channel
+ indicated by the <Channel ID>. A client that is banned from
+ channel is no longer able to join the channel. The client which
+ is executing this command MUST have at least channel operator
+ privileges on the channel.
+
+ 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>, if present, indicates the
+ information to be added to or removed from the ban list. It
+ may include a string for matching clients, public key of a
+ client or Client ID of a client. The <ban list> format is
+ as follows:
+
+ 2 bytes - Number of arguments in the list
+ variable length - Argument Payloads
+
+ The following Argument Types has been defined for ban list
+ Argument Payloads:
+
+ 0x01 - Argument is an ban string of following format:
+
+ [<nickname>[@<server>]!][<username>]@[<hostname or IP/MASK>]
+
+ The <hostname> may also be in format of IP/MASK to indicate
+ a network.
+
+ 0x02 - Argument is the public key of a client
+ 0x03 - Argument is the Client ID of a client
+
+ If unknown type value is received or there is invalid amount of
+ Argument Payloads present in the list, the command MUST be
+ discarded. When argument that is to be deleted from the ban
+ list does not exist in the list the argument is ignored.
+
+ The server MUST send the notify type SILC_NOTIFY_TYPE_BAN to its
+ primary router after adding to or removing from the ban list.
+ The wildcards MAY be used with this command. If this command
+ is executed without the ban arguments the command merely replies
+ with the current ban list.
+
+ Reply messages to the command:
+
+ Max Arguments: 3
+ Arguments: (1) <Status Payload> (2) <Channel ID>
+ (3) [<ban list>]
+
+ This command replies with the <Channel ID> of the channel and
+ the current <ban list> of the channel if it exists.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
+ SILC_STATUS_ERR_NO_CHANNEL_ID
+ SILC_STATUS_ERR_NOT_ON_CHANNEL
+ SILC_STATUS_ERR_NO_CHANNEL_PRIV
+ SILC_STATUS_ERR_RESOURCE_LIMIT
+
+
+
+
+ 21 SILC_COMMAND_DETACH
+
+ Max Arguments: 0
+ Arguments:
+
+ This command is used to detach from the network. Client can
+ send this command to its server to indicate that it will be
+ detached. By detaching the client remains in the network but
+ the actual network connection to the server is closed. The
+ client may then later resume the old session back.
+
+ When this command is received the server MUST check that the
+ client is locally connected client, and set the user mode
+ SILC_UMODE_DETACHED flag. The SILC_NOTIFY_TYPE_UMODE_CHANGE
+ MUST be also sent to routers. The server then sends command
+ reply to this command and closes the network connection.
+ The server MUST NOT remove the client from its lists, or send
+ any signoff notifications for this client. See the [SILC1]
+ for detailed information about detaching.
+
+ Reply messages to the command:
+
+ Max Arguments: 1
+ Arguments: (1) <Status Payload>
+
+ This command replies only with the status indication.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_REGISTERED
+
+
+ 22 SILC_COMMAND_WATCH
+
+ Max Arguments: 3
+ Arguments: (1) <Client ID> (2) [<add nickname>]
+ (3) [<del nickname>]
+
+ This command is used to set up a watch for <add nickname>
+ nickname. When a user in the network appears with the
+ nickname, or signoffs the network or user's mode is changed
+ the client which set up the watch will be notified about
+ this change. This can be used to watch for certain nicknames
+ in the network and receive notifications when for example a
+ friend appears in the network or leaves the network.
+
+ The <del nickname> is a nickname that has been previously
+ added to watch list and is now removed from it. Notifications
+ for that nickname will not be delivered anymore.
+
+ The <Client ID> is the Client ID of the sender of this command.
+
+ The nickname set to watch MUST NOT include any wildcards.
+ Note also that a nickname may match several users since
+ nicknames are not unique. Implementations MAY set limits
+ for how many nicknames client can watch.
+
+ When normal server receives this command from client it
+ MUST send it to its router. Router will process the command
+ and actually keeps the watch list.
+
+ Reply messages to the command:
+
+ Max Arguments: 1
+ Arguments: (1) <Status Payload>
+
+ This command replies only with the status indication.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_BAD_NICKNAME
+ SILC_STATUS_ERR_WILDCARDS
+ SILC_STATUS_ERR_RESOURCE_LIMIT
+ SILC_STATUS_ERR_NO_SUCH_NICK
+ SILC_STATUS_ERR_NICKNAME_IN_USE
+
+
+ 23 SILC_COMMAND_SILCOPER
+
+ Max Arguments: 2
+ Arguments: (1) <username> (2) <authentication payload>
+
+ This command is used by normal client to obtain router operator
+ privileges (also known as SILC operator) on the router. Note
+ that router operator has privileges that supersedes the server
+ operator privileges.
+
+ The <username> is the username set in the server configurations
+ as operator. The <authentication payload> is the data that the
+ client is authenticated against. It may be passphrase prompted
+ for user on client's screen or it may be public key or certificate
+ authentication data (data signed with private key). The public
+ key that router will use to verify the signature found in the
+ payload should be verified. It is recommended that the public
+ key is saved locally in the router and router would not use
+ any public keys received during the SKE.
+
+ Difference between router operator and server operator is that
+ router operator is able to handle cell level properties while
+ server operator (even on router server) is able to handle only
+ local properties, such as, local connections and normal server
+ administration. The router operator is also able to use the
+ SILC_COMMAND_KILL command.
+
+ After changing the mode server MUST send the notify type
+ SILC_NOTIFY_TYPE_UMODE_CHANGE to its primary router.
+
+ Reply messages to the command:
+
+ Max Arguments: 1
+ Arguments: (1) <Status Payload>
+
+ This command replies only with Status Payload.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_AUTH_FAILED
+
+
+ 24 SILC_COMMAND_LEAVE
+
+ Max Arguments: 1
+ Arguments: (1) <Channel ID>
+
+ This command is used by client to leave a channel the client is
+ joined to.
+
+ When leaving channel the server MUST send the notify type
+ SILC_NOTIFY_TYPE_LEAVE to its primary router and to the channel.
+ The channel key MUST also be re-generated when leaving the channel
+ and distribute it to all clients still currently on the channel.
+ The key MUST NOT be re-generated if the SILC_CMODE_PRIVKEY mode
+ is set.
+
+ Reply messages to the command:
+
+ Max Arguments: 2
+ Arguments: (1) <Status Payload> (2) <Channel ID>
+
+ The <Channel ID> is the ID of left channel.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
+ SILC_STATUS_ERR_BAD_CHANNEL_ID
+ SILC_STATUS_ERR_NO_CHANNEL_ID
+
+
+ 25 SILC_COMMAND_USERS
+
+ Max Arguments: 2
+ Arguments: (1) [<Channel ID>] (2) [<channel name>]
+
+ This command is used to list user names currently on the requested
+ channel; either the argument <Channel ID> or the <channel name>.
+ One of these arguments must be present. The server MUST resolve
+ the joined clients and reply with a lists of users on the channel
+ and with list of user modes on the channel.
+
+ If the requested channel is a private or secret channel, this
+ command MUST NOT send the list of users, except if the sender is
+ on the channel, or the sender is a server. Otherwise, error is
+ returned to the sender.
+
+ Reply messages to the command:
+
+ Max Arguments: 5
+ Arguments: (1) <Status Payload> (2) <Channel ID>
+ (3) <list count> (4) <Client ID list>
+ (5) <client mode list>
+
+ This command replies with the Channel ID of the requested channel
+ Client ID list of the users on the channel and list of their modes.
+ The Client ID list has Client ID's of all users in the list. The
+ <Client ID list> is formed by adding Client ID's one after another.
+ The <client mode list> is formed by adding client's user modes on
+ the channel one after another (4 bytes (32 bits) each). The <list
+ count> of length of 4 bytes (32 bits), tells the number of entries
+ in the lists. Both lists MUST have equal number of entries.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
+ SILC_STATUS_ERR_BAD_CHANNEL_ID
+ SILC_STATUS_ERR_NO_CHANNEL_ID
+ SILC_STATUS_ERR_NOT_ON_CHANNEL
+
+
+ 26 SILC_COMMAND_GETKEY
+
+ Max Arguments: 1
+ Arguments: (1) <ID Payload>
+
+ This command is used to fetch the public key of the client or
+ server indicated by the <ID Payload>. The public key is fetched
+ from the server where to the client is connected.
+
+ Reply messages to the command:
+
+ Max Arguments: 3
+ Arguments: (1) <Status Payload> (2) <ID Payload>
+ (3) [<Public Key Payload>]
+
+ This command replies with the client's or server's ID and with
+ the <Public Key Payload>.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
+ SILC_STATUS_ERR_NO_SUCH_SERVER_ID
+
+
+ 27 SILC_COMMAND_SERVICE
+
+ Max Arguments: 256
+ Arguments: (1) [<service name>] (2) [<auth payload>]
+ (n) [...]
+
+ This command is used to negotiate a service agreement with a
+ remote server. If this command is given without arguments it
+ MAY return the service list, if it is publicly available. The
+ <service name> is a service specific identifier, and the
+ <auth payload> MAY be used to authenticate the requester to the
+ remote service. The authentication to a service may be based
+ on previous agreement with the requester and the service
+ provider. The command MAY also take additional service
+ specific arguments.
+
+ This document does not specify any services. How the services
+ are configured and put available in a server is also out of
+ scope of this document.
+
+ This command MAY be used by client to start using some service
+ in a server, but it also MAY be used by server to negotiate
+ to start using a service in some other server or router.
+
+ After the negotiation is done both of the parties need to know
+ from the service identifier how the service can be used. The
+ service can be considered to be a protocol which both of the
+ parties need to support.
+
+ Reply messages to the command:
+
+ Max Arguments: 256
+ Arguments: (1) <Status Payload> (2) [<service list>]
+ (3) [<service name>] (n) [...]
+
+
+ This command MAY reply with the <service list> when command is
+ given without arguments, and the list is a comma separated list
+ of service identifiers. The <service name> is the service that
+ the sender requested and this is provided when the server has
+ accepted the sender to use the <service name>. The command
+ reply MAY also have additional service specific arguments.
+
+ Status messages:
+
+ SILC_STATUS_OK
+ SILC_STATUS_ERR_NOT_REGISTERED
+ SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+ SILC_STATUS_ERR_TOO_MANY_PARAMS
+ SILC_STATUS_ERR_NO_SUCH_SERVICE
+ SILC_STATUS_ERR_AUTH_FAILED
+ SILC_STATUS_ERR_PERM_DENIED
+
+
+
+
+ 28 - 199
+
+ Currently undefined commands.
+
+
+ 200 - 254
+
+ These commands are reserved for private use and will not be defined
+ in this document.
+
+
+ 255 SILC_COMMAND_MAX
+
+ Reserved command. This must not be sent.
+.in 3
+
+
+.ti 0
+2.4 SILC Command Status Payload
+
+Command Status Payload is sent in command reply messages to indicate
+the status of the command. The payload is one of argument in the
+command thus this is the data area in Command Argument Payload described
+in [SILC2]. The payload is only 2 bytes in length. The following
+diagram represents the Command Status Payload (fields are always in
+MSB first order).
+
+
+.in 21
+.nf
+ 1
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| Status | Error |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+.in 3
+
+.ce
+Figure 6: SILC Command Status Payload
+
+
+.in 6
+o Status (1 byte) - Indicates the status message type,
+ error, start of list, entry of list or end of list.
+
+o Error (1 byte) - Indicates the error if the Status
+ field is some list status, which means there are list
+ of errors.
+.in 3
+
+The values in Status and Error fields are set according
+the following rules:
+
+.in 6
+o If there is single reply and error has not occurred
+ then Status field includes value SILC_STATUS_OK, and
+ the Error field MUST be ignored (and set to zero
+ value).
+
+o If there is single error, then Status field includes
+ one of the error values, and the Error field MUST be
+ ignored (and set to zero value).
+
+o If there will be multiple successful command replies
+ then Status field includes SILC_STATUS_LIST_START,
+ SILC_STATUS_LIST_ITEM or SILC_STATUS_LIST_END value,
+ and Error field is set to SILC_STATUS_OK.
+
+o If there are multiple error replies then Status field
+ includes SILC_STATUS_LIST_START, SILC_STATUS_LIST_ITEM
+ or SILC_STATUS_LIST_END value, and the Error field
+ includes the error value.
+.in 3
+
+This way it is possible to send single successful or
+single error reply, but also multiple successful and
+multiple error replies. Note that it is possible to
+send both list of successful replies and list of error
+replies at the same time, however in this case the
+list of error replies MUST be sent after the successful
+replies. This way the recipient may ignore the multiple
+errors if it wishes to do so. Also note that in this
+case the successful and error replies belong to the
+same list.
+
+All Status messages are described in the next section.
+
+
+.ti 0
+3 SILC Status Types
+
+Status messages are returned in SILC protocol in command reply
+packet and in notify packet. The SILC_PACKET_COMMAND_REPLY is
+the command reply packet and status types are sent inside the
+Status Payload as one of command reply argument, as defined in
+previous sections. For SILC_PACKET_NOTIFY packet they can be sent
+as defined in [SILC2] for SILC_NOTIFY_TYPE_ERROR type. The same
+types defined in this section are used in both cases.
+
+When returning status messages in the command reply message they
+indicate whether the command was executed without errors. If error
+occurred the status indicates which error occurred.
+
+When sending status messages in SILC_NOTIFY_TYPE_ERROR notify type
+they always send some error status. Usually they are sent to
+indicate that error occurred while processing some SILC packet.
+Please see the [SILC1] and [SILC2] for more information sending
+status types in SILC_NOTIFY_TYPE_ERROR notify.
+
+The Status Types are only numeric values and the receiver must
+convert the numeric values into human readable messages if this
+is desired in the application.
+
+List of all defined status types:
+
+.in 0
+ Generic status messages:
+
+ 0 SILC_STATUS_OK
+
+ Ok status. Everything went Ok. The status payload maybe
+ safely ignored in this case.
+
+ 1 SILC_STATUS_LIST_START
+
+ Start of the list. There will be several command replies and
+ this reply is the start of the list.
+
+ 2 SILC_STATUS_LIST_ITEM
+
+ Item in the list. This is one of the item in the list but not the
+ first or last one.
+
+ 3 SILC_STATUS_LIST_END
+
+ End of the list. There were several command replies and this
+ reply is the last of the list. There won't be other replies
+ belonging to this list after this one.
+
+ 4 - 9
+
+ Currently undefined and has been reserved for the future.
+
+
+ Error status message:
+
+
+
+ 10 SILC_STATUS_ERR_NO_SUCH_NICK
+
+ "No such nickname". Requested nickname does not exist.
+
+ 11 SILC_STATUS_ERR_NO_SUCH_CHANNEL
+
+ "No such channel". Requested channel name does not exist.
+
+ 12 SILC_STATUS_ERR_NO_SUCH_SERVER
+
+ "No such server". Requested server name does not exist.
+
+ 13 SILC_STATUS_ERR_INCOMPLETE_INFORMATION
+
+ "Incomplete registration information". Information remote
+ sent was incomplete.
+
+ 14 SILC_STATUS_ERR_NO_RECIPIENT
+
+ "No recipient given". Command required recipient which was
+ not provided.
+
+ 15 SILC_STATUS_ERR_UNKNOWN_COMMAND
+
+ "Unknown command". Command sent to server is unknown by the
+ server.
+
+ 16 SILC_STATUS_ERR_WILDCARDS
+
+ "Wildcards cannot be used". Wildcards were provided but they
+ weren't permitted.
+
+ 17 SILC_STATUS_ERR_NO_CLIENT_ID
+
+ "No Client ID given". Client ID were expected as command
+ parameter but were not found.
+
+ 18 SILC_STATUS_ERR_NO_CHANNEL_ID
+
+ "No Channel ID given". Channel ID were expected as command
+ parameter but were not found.
+
+ 19 SILC_STATUS_ERR_NO_SERVER_ID
+
+ "No Serve ID given". Server ID were expected as command
+ parameter but were not found.
+
+ 20 SILC_STATUS_ERR_BAD_CLIENT_ID
+
+ "Bad Client ID". Client ID provided were erroneous.
+
+ 21 SILC_STATUS_ERR_BAD_CHANNEL_ID
+
+ "Bad Channel ID". Channel ID provided were erroneous.
+
+ 22 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
+
+ "No such Client ID". Client ID provided does not exist.
+ The unknown Client ID MUST be provided as next argument
+ in the reply.
+
+ 23 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
+
+ "No such Channel ID". Channel ID provided does not exist.
+ The unknown Channel ID MUST be provided as next argument
+ in the reply.
+
+ 24 SILC_STATUS_ERR_NICKNAME_IN_USE
+
+ "Nickname already exists". Nickname created could not be
+ registered because number of same nicknames were already set to
+ maximum. This is not expected to happen in real life but is
+ possible to occur.
+
+ 25 SILC_STATUS_ERR_NOT_ON_CHANNEL
+
+ "You are not on that channel". The command were specified for
+ channel user is not currently on.
+
+ 26 SILC_STATUS_ERR_USER_NOT_ON_CHANNEL
+
+ "They are not on channel". The requested target client is not
+ on requested channel.
+
+ 27 SILC_STATUS_ERR_USER_ON_CHANNEL
+
+ "User already on channel". User were invited on channel they
+ already are on.
+
+ 28 SILC_STATUS_ERR_NOT_REGISTERED
+
+ "You have not registered". User executed command that requires
+ the client to be registered on the server before it may be
+ executed.
+
+ 29 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
+
+ "Not enough parameters". Command requires more parameters
+ than provided.
+
+ 30 SILC_STATUS_ERR_TOO_MANY_PARAMS
+
+ "Too many parameters". Too many parameters were provided
+ for the command.
+
+ 31 SILC_STATUS_ERR_PERM_DENIED
+
+ "Permission denied". Generic permission denied error status
+ to indicate disallowed access.
+
+ 32 SILC_STATUS_ERR_BANNED_FROM_SERVER
+
+ "You are banned from this server". The client tried to register
+ on server that has explicitly denied this host to connect.
+
+ 33 SILC_STATUS_ERR_BAD_PASSWORD
+
+ "Cannot join channel. Incorrect password". Password provided for
+ channel were not accepted.
+
+ 34 SILC_STATUS_ERR_CHANNEL_IS_FULL
+
+ "Cannot join channel. Channel is full". The channel is full
+ and client cannot be joined to it.
+
+ 35 SILC_STATUS_ERR_NOT_INVITED
+
+ "Cannot join channel. You have not been invited". The channel
+ is invite only channel and client has not been invited.
+
+ 36 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
+
+ "Cannot join channel. You have been banned". The client has
+ been banned from the channel.
+
+ 37 SILC_STATUS_ERR_UNKNOWN_MODE
+
+ "Unknown mode". Mode provided by the client were unknown to
+ the server.
+
+ 38 SILC_STATUS_ERR_NOT_YOU
+
+ "Cannot change mode for other users". User tried to change
+ someone else's mode.
+
+ 39 SILC_STATUS_ERR_NO_CHANNEL_PRIV
+
+ "Permission denied. You are not channel operator". Command may
+ be executed only by channel operator.
+
+ 40 SILC_STATUS_ERR_NO_CHANNEL_FOPRIV
+
+ "Permission denied. You are not channel founder". Command may
+ be executed only by channel operator.
+
+ 41 SILC_STATUS_ERR_NO_SERVER_PRIV
+
+ "Permission denied. You are not server operator". Command may
+ be executed only by server operator.
+
+ 42 SILC_STATUS_ERR_NO_ROUTER_PRIV
+
+ "Permission denied. You are not SILC operator". Command may be
+ executed only by router (SILC) operator.
+
+ 43 SILC_STATUS_ERR_BAD_NICKNAME
+
+ "Bad nickname". Nickname requested contained illegal characters
+ or were malformed.
+
+ 44 SILC_STATUS_ERR_BAD_CHANNEL
+
+ "Bad channel name". Channel requested contained illegal characters
+ or were malformed.
+
+ 45 SILC_STATUS_ERR_AUTH_FAILED
+
+ "Authentication failed". The authentication data sent as
+ argument were wrong and thus authentication failed.
+
+ 46 SILC_STATUS_ERR_UNKOWN_ALGORITHM
+
+ "The algorithm was not supported." The server does not support the
+ requested algorithm.
+
+ 47 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
+
+ "No such Server ID". Server ID provided does not exist.
+ The unknown Server ID MUST be provided as next argument
+ in the reply.
+
+ 48 SILC_STATUS_ERR_RESOURCE_LIMIT
+
+ "No more resources available". This can mean that server cannot
+ or will not accept something due to resource limitations.
+
+ 49 SILC_STATUS_ERR_NO_SUCH_SERVICE
+
+ "Service does not exist". Requested service identifier is
+ unknown.
+
+ 50 SILC_STATUS_ERR_NOT_AUTHENTICATED
+
+ "You have not been authenticated". Remote connection is not
+ authenticated even though it is supposed to be.
+
+ 51 SILC_STATUS_ERR_BAD_SERVER_ID
+
+ "Server ID is not valid". Provided server ID is not valid.
+
+ 52 SILC_STATUS_ERR_KEY_EXCHANGE_FAILED
+
+ "Key exchange failed". Key Exchange protocol failed.
+
+ 53 SILC_STATUS_ERR_BAD_VERSION
+
+ "Bad version". Protocol or software version mismatch.
+
+ 54 SILC_STATUS_ERR_TIMEDOUT
+
+ "Operation timed out". Operation or service request timed
+ out, and thus was not processed.
+
+ 55 SILC_STATUS_ERR_UNSUPPORTED_PUBLIC_KEY
+
+ "Unsupported public key type". The public key or certificate
+ type is not supported in this implementation.
+
+ 56 SILC_STATUS_ERR_OPERATION_ALLOWED
+
+ "Operation is not allowed". A operation, for example a command,
+ is not allowed or it's execution is not allowed.
+
+.in 3
+
+
+.ti 0
+4 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
+5 References
+
+[SILC1] Riikonen, P., "Secure Internet Live Conferencing (SILC),
+ Protocol Specification", Internet Draft, May 2002.
+
+[SILC2] Riikonen, P., "SILC Packet Protocol", Internet Draft,
+ May 2002.
+
+[SILC3] Riikonen, P., "SILC Key Exchange and Authentication
+ Protocols", 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.
+
+[RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO
+ 10646", RFC 2279, January 1998.
+
+[ATTRS] Riikonen, P., "User Online Presence and Information
+ Attributes", Internet Draft, May 2002.
+
+
+.ti 0
+6 Author's Address
+
+.nf
+Pekka Riikonen
+Snellmaninkatu 34 A 15
+70100 Kuopio
+Finland
+
+EMail: priikone@iki.fi
+
+This Internet-Draft expires XXX
+
+
+.ti 0
+Appendix A
+
+This appendix defines the usage of the <Requested Attributes> argument in
+the SILC_COMMAND_WHOIS command. The attributes are defined in [ATTRS],
+and may be used to request additional information about the user. Since
+the information that may be requested using the attributes is something
+that server cannot deliver to the sender, it is possible to send the WHOIS
+command directly to the destination client whom will then provide the
+requested attributes. This requires the servers to relay the WHOIS
+command to the client, and it requires capability for handling the WHOIS
+command in the client end.
+
+The <Requested Attributes> MAY include several attributes that are
+requested. The format and encoding of the <Requested Attributes> is as
+defined in [ATTRS]. When <Requested Attributes> argument is set the
+server MAY process the attributes to see whether it can narrow down
+the WHOIS search, for example when searching with a nickname. The
+normal servers MUST process the WHOIS command as normal WHOIS command,
+that is to send the command directly to the router. The router MAY
+process the attributes, but it MUST send the command to the server
+that owns the requested client.
+
+The server that owns the client and receives the command MUST check
+whether the client is detached from the network. If it is detached,
+that is the user mode has the SILC_UMODE_DETACHED mode set, it SHOULD
+process the attributes and provide as many of the requested attributes
+as possible and then send reply back to the sender. If the client is
+active in the network it MUST send the command to the client for
+processing.
+
+The client receiving WHOIS command SHOULD check whether the
+<Requested Attributes> argument is set. If it is not set then the
+WHOIS command SHOULD be discarded. The client processes the requested
+attributes and SHOULD reply to each of the requested attribute with
+either valid value, or with an indication that the requested attribute
+is not known or supported. This is to be done as defined in [ATTRS].
+The client always MUST send a reply to the command when some attributes
+were requested. The client MAY also add additional attributes to the
+reply even if they were not requested. The client MAY also digitally
+sign the attributes with ATTRIBUTE_USER_DIGITAL_SIGNATURE as defined
+in [ATTRS]. Then the client sends the reply back to the sender of
+the command. The command reply that client assembles does not need
+to include any other argument but the <Status Payload> (1), and the
+<Attributes> (11). The server receiving reply from client MUST allow
+this sort of command reply for WHOIS command.
+
+The information received from the client MAY be cached in the
+server's end. The caching may be desired for example if the client
+can be detached from the network. This way the server is then able
+to provide at least partial information for a requester. The
+server MAY also process the command reply and verify whether the
+attributes provided in the reply are actually valid. If it can do
+this, and verify that they indeed are valid values it MAY append
+a digital signature at the end of the attributes with the
+ATTRIBUTE_SERVER_DIGITAL_SIGNATURE as defined in [ATTRS]. The
+server then MUST provide valid WHOIS command reply to the sender
+of the command. Other servers and routers that receive the command
+reply en route to the original sender MAY also cache the information.
+
+The client which receives the command reply to the WHOIS command
+SHOULD verify the ATTRIBUTE_USER_DIGITAL_SIGNATURE and the
+ATTRIBUTE_SERVER_DIGITAL_SIGNATURE if they are provided.
--- /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 XXX
+.ds CH
+.na
+.hy 0
+.in 0
+.nf
+Network Working Group P. Riikonen
+Internet-Draft
+draft-riikonen-silc-ke-auth-07.txt XXX
+Expires: XXX
+
+.in 3
+
+.ce 2
+SILC Key Exchange and Authentication Protocols
+<draft-riikonen-silc-ke-auth-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 two protocols used in the Secure Internet Live
+Conferencing (SILC) protocol, specified in the Secure Internet Live
+Conferencing, Protocol Specification [SILC1]. The SILC Key Exchange
+(SKE) protocol provides secure key exchange between two parties
+resulting into shared secret key material. The protocol is based
+on Diffie-Hellman key exchange algorithm and its functionality is
+derived from several key exchange protocols. SKE use best parts
+of the SSH2 Key Exchange protocol, Station-To-Station (STS) protocol
+and the OAKLEY Key Determination protocol [OAKLEY].
+
+The second protocol, SILC Connection Authentication protocol provides
+user level authentication used when creating connections in SILC
+network. The protocol is transparent to the authentication data
+which means that it can be used to authenticate the user with, for
+example, passphrase (pre-shared secret) or public key (and certificate)
+based on digital signatures.
+
+
+
+.ti 0
+Table of Contents
+
+.nf
+1 Introduction .................................................. 2
+ 1.1 Requirements Terminology .................................. 3
+2 SILC Key Exchange Protocol .................................... 3
+ 2.1 Key Exchange Payloads ..................................... 4
+ 2.1.1 Key Exchange Start Payload .......................... 4
+ 2.1.2 Key Exchange Payload ................................ 8
+ 2.2 Key Exchange Procedure .................................... 11
+ 2.3 Processing the Key Material ............................... 12
+ 2.4 SILC Key Exchange Groups .................................. 14
+ 2.4.1 diffie-hellman-group1 ............................... 14
+ 2.4.2 diffie-hellman-group2 ............................... 15
+ 2.4.3 diffie-hellman-group3 ............................... 15
+ 2.5 Key Exchange Status Types ................................. 16
+3 SILC Connection Authentication Protocol ....................... 17
+ 3.1 Connection Auth Payload ................................... 18
+ 3.2 Connection Authentication Types ........................... 19
+ 3.2.1 Passphrase Authentication ........................... 19
+ 3.2.2 Public Key Authentication ........................... 20
+ 3.3 Connection Authentication Status Types .................... 21
+4 Security Considerations ....................................... 21
+5 References .................................................... 21
+6 Author's Address .............................................. 23
+
+
+.ti 0
+List of Figures
+
+.nf
+Figure 1: Key Exchange Start Payload
+Figure 2: Key Exchange Payload
+Figure 3: Connection Auth Payload
+
+
+.ti 0
+1 Introduction
+
+This memo describes two protocols used in the Secure Internet Live
+Conferencing (SILC) protocol specified in the Secure Internet Live
+Conferencing, Protocol Specification [SILC1]. The SILC Key Exchange
+(SKE) protocol provides secure key exchange between two parties
+resulting into shared secret key material. The protocol is based on
+Diffie-Hellman key exchange algorithm and its functionality is derived
+from several key exchange protocols. SKE use best parts of the SSH2
+Key Exchange protocol, Station-To-Station (STS) protocol and the
+OAKLEY Key Determination protocol [OAKLEY].
+
+The second protocol, SILC Connection Authentication protocol provides
+user level authentication used when creating connections in SILC
+network. The protocol is transparent to the authentication data which
+means that it can be used to authenticate the user with, for example,
+passphrase (pre-shared secret) or public key (and certificate) based
+on digital signatures.
+
+The basis of secure SILC session requires strong and secure key exchange
+protocol and authentication. The authentication protocol is secured and
+no authentication data is ever sent in the network without encrypting
+and authenticating it first. Thus, authentication protocol may be used
+only after the key exchange protocol has been successfully completed.
+
+This document constantly refers to other SILC protocol specifications
+that should be read to be able to fully understand the functionality
+and purpose of these protocols. The most important references are
+the Secure Internet Live Conferencing, Protocol Specification [SILC1]
+and the SILC Packet Protocol [SILC2].
+
+The protocol is intended to be used with the SILC protocol thus it
+does not define own framework that could be used. The framework is
+provided by the SILC protocol.
+
+
+.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 Key Exchange Protocol
+
+SILC Key Exchange Protocol (SKE) is used to exchange shared secret
+between connecting entities. The result of this protocol is a key
+material used to secure the communication channel. The protocol use
+Diffie-Hellman key exchange algorithm and its functionality is derived
+from several key exchange protocols. SKE use best parts of the SSH2
+Key Exchange protocol, Station-To-Station (STS) protocol and the OAKLEY
+Key Determination protocol. The protocol does not claim any conformance
+to any of these protocols, they were only used as a reference when
+designing this protocol.
+
+The purpose of SILC Key Exchange protocol is to create session keys to
+be used in current SILC session. The keys are valid only for some period
+of time (usually an hour) or at most until the session ends. These keys
+are used to protect packets traveling between the two entities.
+Usually all traffic is secured with the key material derived from this
+protocol.
+
+The Diffie-Hellman implementation used in the SILC SHOULD be compliant
+to the PKCS #3.
+
+
+.ti 0
+2.1 Key Exchange Payloads
+
+During the key exchange procedure public data is sent between initiator
+and responder. This data is later used in the key exchange procedure.
+There are several payloads used in the key exchange. As for all SILC
+packets, SILC Packet Header, described in [SILC2], is at the start of
+all packets sent in during this protocol. All the fields in the
+following payloads are in MSB (most significant byte first) order.
+Following descriptions of these payloads.
+
+
+.ti 0
+2.1.1 Key Exchange Start Payload
+
+The key exchange between two entities MUST be started by sending the
+SILC_PACKET_KEY_EXCHANGE packet containing Key Exchange Start Payload.
+Initiator sends the Key Exchange Start Payload to the responder filled
+with all security properties it supports. The responder then checks
+whether it supports the security properties.
+
+It then sends a Key Exchange Start Payload to the initiator filled with
+security properties it selected from the original payload. The payload
+sent by responder MUST include only one chosen property per list. The
+character encoding for the security property values as defined in [SILC1]
+SHOULD be UTF-8 [RFC2279] in Key Exchange Start Payload.
+
+The Key Exchange Start Payload is used to tell connecting entities what
+security properties and algorithms should be used in the communication.
+The Key Exchange Start Payload is sent only once per session. Even if
+the PFS (Perfect Forward Secrecy) flag is set the Key Exchange Start
+Payload is not re-sent. When PFS is desired the Key Exchange Payloads
+are sent to negotiate new key material. The procedure is equivalent to
+the very first negotiation except that the Key Exchange Start Payload
+is not sent.
+
+As this payload is used only with the very first key exchange the payload
+is never encrypted, as there are no keys to encrypt it with.
+
+A cookie is also sent in this payload. A cookie is used to randomize the
+payload so that none of the key exchange parties can determine this
+payload before the key exchange procedure starts. The cookie MUST be
+returned to the original sender unmodified by the responder.
+
+Following diagram represents the Key Exchange Start Payload. The lists
+mentioned below are always comma (`,') separated and the list MUST NOT
+include white spaces (` ').
+
+
+.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
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| RESERVED | Flags | Payload Length |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| |
++ +
+| |
++ Cookie +
+| |
++ +
+| |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| Version String Length | |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
+| |
+~ Version String ~
+| |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| Key Exchange Grp Length | |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
+| |
+~ Key Exchange Groups ~
+| |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| PKCS Alg Length | |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
+| |
+~ PKCS Algorithms ~
+| |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| Encryption Alg Length | |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
+| |
+~ Encryption Algorithms ~
+| |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| Hash Alg Length | |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
+| |
+~ Hash Algorithms ~
+| |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| HMAC Length | |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
+| |
+~ HMACs ~
+| |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| Compression Alg Length | |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
+| |
+~ Compression Algorithms ~
+| |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+.in 3
+
+.ce
+Figure 1: Key Exchange Start Payload
+
+
+
+.in 6
+o RESERVED (1 byte) - Reserved field. Sender fills this with
+ zero (0) value.
+
+o Flags (1 byte) - Indicates flags to be used in the key
+ exchange. Several flags can be set at once by ORing the
+ flags together. The following flags are reserved for this
+ field:
+
+ No flags 0x00
+
+ In this case the field is ignored.
+
+ IV Included 0x01
+
+ This flag is used to indicate that Initial Vector (IV)
+ in encryption will be included in the ciphertext
+ which the recipient must use in decryption. The IV
+ MUST be set after the last ciphertext block. With
+ this flag it is possible to use SILC protocol on
+ unreliable transport such as UDP/IP which may cause
+ packet reordering and packet losses. By default,
+ this flag is not set and thus IV is not included
+ in the ciphertext. Setting this flag increases the
+ ciphertext size by one ciphertext block. Responder
+ MAY override this flag for the initiator.
+
+ PFS 0x02
+
+ Perfect Forward Secrecy (PFS) to be used in the
+ key exchange protocol. If not set, re-keying
+ is performed using the old key. See the [SILC1]
+ for more information on this issue. When PFS is
+ used, re-keying and creating new keys for any
+ particular purpose MUST cause new key exchange.
+ In this key exchange only the Key Exchange Payload
+ is sent and the Key Exchange Start Payload MUST
+ NOT be sent. When doing PFS the Key Exchange
+ Payloads are encrypted with the old keys.
+
+ Mutual Authentication 0x04
+
+ Both of the parties will perform authentication
+ by providing signed data for the other party to
+ verify. By default, only responder will provide
+ the signature data. If this is set then the
+ initiator must also provide it. Initiator MAY
+ set this but also responder MAY set this even if
+ initiator did not set it.
+
+ Rest of the flags are reserved for the future and
+ MUST NOT be set.
+
+o Payload Length (2 bytes) - Length of the entire Key Exchange
+ Start payload, not including any other field.
+
+o Cookie (16 bytes) - Cookie that randomize this payload so
+ that each of the party cannot determine the payload before
+ hand. This field MUST be present.
+
+o Version String Length (2 bytes) - The length of the Version
+ String field, not including any other field.
+
+o Version String (variable length) - Indicates the version of
+ the sender of this payload. Initiator sets this when sending
+ the payload and responder sets this when it replies by sending
+ this payload. See [SILC1] for definition for the version
+ string format. This field MUST be present and include valid
+ version string.
+
+o Key Exchange Grp Length (2 bytes) - The length of the
+ key exchange group list, not including any other field.
+
+o Key Exchange Group (variable length) - The list of
+ key exchange groups. See the section 2.4 SILC Key Exchange
+ Groups for definitions of these groups. This field MUST
+ be present.
+
+o PKCS Alg Length (2 bytes) - The length of the PKCS algorithms
+ list, not including any other field.
+
+o PKCS Algorithms (variable length) - The list of PKCS
+ algorithms. This field MUST be present.
+
+o Encryption Alg Length (2 bytes) - The length of the encryption
+ algorithms list, not including any other field.
+
+o Encryption Algorithms (variable length) - The list of
+ encryption algorithms. This field MUST be present.
+
+o Hash Alg Length (2 bytes) - The length of the Hash algorithm
+ list, not including any other field.
+
+o Hash Algorithms (variable length) - The list of Hash
+ algorithms. The hash algorithms are mainly used in the
+ SKE protocol. This field MUST be present.
+
+o HMAC Length (2 bytes) - The length of the HMAC list, not
+ including any other field.
+
+o HMACs (variable length) - The list of HMACs. The HMAC's
+ are used to compute the Message Authentication Code (MAC)
+ of the SILC packets. This field MUST be present.
+
+o Compression Alg Length (2 bytes) - The length of the
+ compression algorithms list, not including any other field.
+
+o Compression Algorithms (variable length) - The list of
+ compression algorithms. This field MAY be omitted.
+.in 3
+
+
+.ti 0
+2.1.2 Key Exchange Payload
+
+Key Exchange payload is used to deliver the public key (or certificate),
+the computed Diffie-Hellman public value and possibly signature data
+from one party to the other. When initiator is using this payload
+and the Mutual Authentication flag is not set then the initiator MUST
+NOT provide the signature data. If the flag is set then the initiator
+MUST provide the signature data so that the responder can verify it.
+
+The Mutual Authentication flag is usually used when a separate
+authentication protocol will not be executed for the initiator of the
+protocol. This is case for example when the SKE is performed between
+two SILC clients. In normal case, where client is connecting to a
+server, or server is connecting to a router the Mutual Authentication
+flag MAY be omitted. However, if the connection authentication protocol
+for the connecting entity is not based on digital signatures (it is
+based on pre-shared key) then the Mutual Authentication flag SHOULD be
+enabled. This way the connecting entity has to provide proof of
+possession of the private key for the public key it will provide in
+this protocol.
+
+When performing re-key with PFS selected this is the only payload that
+is sent in the SKE protocol. The Key Exchange Start Payload MUST NOT
+be sent at all. However, this payload does not have all the fields
+present. In the re-key with PFS the public key and a possible signature
+data SHOULD NOT be present. If they are present they MUST be ignored.
+The only field that is present is the Public Data that is used to create
+the new key material. In the re-key the Mutual Authentication flag, that
+may be set in the initial negotiation, MUST also be ignored.
+
+This payload is sent inside SILC_PACKET_KEY_EXCHANGE_1 and inside
+SILC_PACKET_KEY_EXCHANGE_2 packet types. The initiator uses the
+SILC_PACKET_KEY_EXCHANGE_1 and the responder the latter.
+
+The following diagram represent the Key Exchange 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 of the party (or certificate) ~
+| |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| Public Data Length | |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
+| |
+~ Public Data ~
+| |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| Signature Length | |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
+| |
+~ Signature Data ~
+| |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+.in 3
+
+.ce
+Figure 2: Key Exchange 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. Following types are defined:
+
+ 1 SILC style public key (mandatory)
+ 2 SSH2 style public key (optional)
+ 3 X.509 Version 3 certificate (optional)
+ 4 OpenPGP certificate (optional)
+ 5 SPKI certificate (optional)
+
+ The only required type to support is type number 1. See
+ [SILC1] for the SILC public key specification. See
+ SSH2 public key specification in [SSH-TRANS]. See X.509v3
+ certificate specification in [PKIX-Part1]. See OpenPGP
+ certificate specification in [PGP]. See SPKI certificate
+ specification in [SPKI]. If this field includes zero (0)
+ or unsupported type number the protocol MUST be aborted
+ sending SILC_PACKET_FAILURE message and the connection SHOULD
+ be closed immediately.
+
+o Public Key (or certificate) (variable length) - The
+ public key or certificate of the party. This public key
+ is used to verify the digital signature. The public key
+ or certificate in this field is encoded in the manner as
+ defined in their respective definitions; see previous field.
+
+o Public Data Length (2 bytes) - The length of the Public Data
+ field, not including any other field.
+
+o Public Data (variable length) - The public data to be
+ sent to the receiver (Diffie-Hellman public values). See
+ section 2.2 Key Exchange Procedure for detailed description
+ how this field is computed. This value is binary encoded.
+
+o Signature Length (2 bytes) - The length of the signature,
+ not including any other field.
+
+o Signature Data (variable length) - The signature signed
+ by the sender. The receiver of this signature MUST
+ verify it. The verification is done using the sender's
+ public key. See section 2.2 Key Exchange Procedure for
+ detailed description how to produce the signature. If
+ the Mutual Authentication flag is not set then initiator
+ MUST NOT provide this field and the Signature Length field
+ MUST be set to zero (0) value. If the flag is set then
+ also the initiator MUST provide this field. The responder
+ always MUST provide this field.
+.in 3
+
+
+.ti 0
+2.2 Key Exchange Procedure
+
+The key exchange begins by sending SILC_PACKET_KEY_EXCHANGE packet with
+Key Exchange Start Payload to select the security properties to be used
+in the key exchange and later in the communication.
+
+After Key Exchange Start Payload has been processed by both of the
+parties the protocol proceeds as follows:
+
+
+Setup: p is a large and public safe prime. This is one of the
+ Diffie Hellman groups. q is order of subgroup (largest
+ prime factor of p). g is a generator and is defined
+ along with the Diffie Hellman group.
+
+ 1. Initiator generates a random number x, where 1 < x < q,
+ and computes e = g ^ x mod p. The result e is then
+ encoded into Key Exchange Payload, with the public key
+ (or certificate) and sent to the responder.
+
+ If the Mutual Authentication flag is set then initiator
+ MUST also produce signature data SIGN_i which the responder
+ will verify. The initiator MUST compute a hash value
+ HASH_i = hash(Initiator's Key Exchange Start Payload |
+ public key (or certificate) | e). The '|' stands for
+ concatenation. It then signs the HASH_i value with its
+ private key resulting a signature SIGN_i.
+
+ 2. Responder generates a random number y, where 1 < y < q,
+ and computes f = g ^ y mod p. It then computes the
+ shared secret KEY = e ^ y mod p, and, a hash value
+ HASH = hash(Initiator's Key Exchange Start Payload |
+ public key (or certificate) | Initiator's public key
+ (or certificate) | e | f | KEY). It then signs
+ the HASH value with its private key resulting a signature
+ SIGN.
+
+ It then encodes its public key (or certificate), f and
+ SIGN into Key Exchange Payload and sends it to the
+ initiator.
+
+ If the Mutual Authentication flag is set then the responder
+ SHOULD verify that the public key provided in the payload
+ is authentic, or if certificates are used it verifies the
+ certificate. The responder MAY accept the public key without
+ verifying it, however, doing so may result to insecure key
+ exchange (accepting the public key without verifying may be
+ desirable for practical reasons on many environments. For
+ long term use this is never desirable, in which case
+ certificates would be the preferred method to use). It then
+ computes the HASH_i value the same way initiator did in the
+ phase 1. It then verifies the signature SIGN_i from the
+ payload with the hash value HASH_i using the received public
+ key.
+
+ 3. Initiator verifies that the public key provided in
+ the payload is authentic, or if certificates are used
+ it verifies the certificate. The initiator MAY accept
+ the public key without verifying it, however, doing
+ so may result to insecure key exchange (accepting the
+ public key without verifying may be desirable for
+ practical reasons on many environments. For long term
+ use this is never desirable, in which case certificates
+ would be the preferred method to use).
+
+ Initiator then computes the shared secret KEY =
+ f ^ x mod p, and, a hash value HASH in the same way as
+ responder did in phase 2. It then verifies the
+ signature SIGN from the payload with the hash value
+ HASH using the received public key.
+
+
+If any of these phases is to fail the SILC_PACKET_FAILURE MUST be sent
+to indicate that the key exchange protocol has failed, and the connection
+SHOULD be closed immediately. Any other packets MUST NOT be sent or
+accepted during the key exchange except the SILC_PACKET_KEY_EXCHANGE_*,
+SILC_PACKET_FAILURE and SILC_PACKET_SUCCESS packets.
+
+The result of this protocol is a shared secret key material KEY and
+a hash value HASH. The key material itself is not fit to be used as
+a key, it needs to be processed further to derive the actual keys to be
+used. The key material is also used to produce other security parameters
+later used in the communication. See section 2.3 Processing the Key
+Material for detailed description how to process the key material.
+
+If the Mutual Authentication flag was set the protocol produces also
+a hash value HASH_i. This value, however, must be discarded.
+
+After the keys are processed the protocol is ended by sending the
+SILC_PACKET_SUCCESS packet. Both entities send this packet to
+each other. After this both parties will start using the new keys.
+
+
+.ti 0
+2.3 Processing the Key Material
+
+Key Exchange protocol produces secret shared key material KEY. This
+key material is used to derive the actual keys used in the encryption
+of the communication channel. The key material is also used to derive
+other security parameters used in the communication. Key Exchange
+protocol produces a hash value HASH as well.
+
+The keys MUST be derived from the key material as follows:
+
+.in 6
+Sending Initial Vector (IV) = hash(0x0 | KEY | HASH)
+Receiving Initial Vector (IV) = hash(0x1 | KEY | HASH)
+Sending Encryption Key = hash(0x2 | KEY | HASH)
+Receiving Encryption Key = hash(0x3 | KEY | HASH)
+Sending HMAC Key = hash(0x4 | KEY | HASH)
+Receiving HMAC Key = hash(0x5 | KEY | HASH)
+.in 3
+
+
+The Initial Vector (IV) is used in the encryption when doing for
+example CBC mode. As many bytes as needed are taken from the start of
+the hash output for IV. Sending IV is for sending key and receiving IV
+is for receiving key. For receiving party, the receiving IV is actually
+sender's sending IV, and, the sending IV is actually sender's receiving
+IV. Initiator uses IV's as they are (sending IV for sending and
+receiving IV for receiving).
+
+The Encryption Keys are derived as well from the hash(). If the hash()
+output is too short for the encryption algorithm more key material MUST
+be produced in the following manner:
+
+.in 6
+K1 = hash(0x2 | KEY | HASH)
+K2 = hash(KEY | HASH | K1)
+K3 = hash(KEY | HASH | K1 | K2) ...
+
+Sending Encryption Key = K1 | K2 | K3 ...
+
+
+K1 = hash(0x3 | KEY | HASH)
+K2 = hash(KEY | HASH | K1)
+K3 = hash(KEY | HASH | K1 | K2) ...
+
+Receiving Encryption Key = K1 | K2 | K3 ...
+.in 3
+
+
+The key is distributed by hashing the previous hash with the original
+key material. The final key is a concatenation of the hash values.
+For Receiving Encryption Key the procedure is equivalent. Sending key
+is used only for encrypting data to be sent. The receiving key is used
+only to decrypt received data. For receiving party, the receive key is
+actually sender's sending key, and, the sending key is actually sender's
+receiving key. Initiator uses generated keys as they are (sending key
+for sending and receiving key for receiving).
+
+The HMAC keys are used to create MAC values to packets in the
+communication channel. As many bytes as needed are taken from the start
+of the hash output to generate the MAC keys.
+
+These procedures are performed by all parties of the key exchange
+protocol. This MUST be done before the protocol has been ended by
+sending the SILC_PACKET_SUCCESS packet, to assure that parties can
+successfully process the key material.
+
+This same key processing procedure MAY be used in the SILC in some
+other circumstances as well. Any changes to this procedure is defined
+separately when this procedure is needed. See the [SILC1] and the
+[SILC2] for these circumstances.
+
+
+.ti 0
+2.4 SILC Key Exchange Groups
+
+The Following groups may be used in the SILC Key Exchange protocol.
+The first group diffie-hellman-group1 is REQUIRED, other groups MAY be
+negotiated to be used in the connection with Key Exchange Start Payload
+and SILC_PACKET_KEY_EXCHANGE packet. However, the first group MUST be
+proposed in the Key Exchange Start Payload regardless of any other
+requested group (however, it does not have to be the first in the list).
+
+
+.ti 0
+2.4.1 diffie-hellman-group1
+
+The length of this group is 1024 bits. This is REQUIRED group.
+The prime is 2^1024 - 2^960 - 1 + 2^64 * { [2^894 pi] + 129093 }.
+
+Its hexadecimal value is
+
+.in 6
+FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
+29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
+EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
+E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED
+EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE65381
+FFFFFFFF FFFFFFFF
+.in 3
+
+
+The generator used with this prime is g = 2. The group order q is
+(p - 1) / 2.
+
+This group was taken from the OAKLEY specification.
+
+
+.ti 0
+2.4.2 diffie-hellman-group2
+
+The length of this group is 1536 bits. This is OPTIONAL group.
+The prime is 2^1536 - 2^1472 - 1 + 2^64 * { [2^1406 pi] + 741804 }.
+
+Its hexadecimal value is
+
+.in 6
+FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
+29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
+EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
+E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED
+EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE45B3D
+C2007CB8 A163BF05 98DA4836 1C55D39A 69163FA8 FD24CF5F
+83655D23 DCA3AD96 1C62F356 208552BB 9ED52907 7096966D
+670C354E 4ABC9804 F1746C08 CA237327 FFFFFFFF FFFFFFFF
+.in 3
+
+The generator used with this prime is g = 2. The group order q is
+(p - 1) / 2.
+
+This group was taken from the OAKLEY specification.
+
+
+.ti 0
+2.4.3 diffie-hellman-group3
+
+The length of this group is 2048 bits. This is OPTIONAL group.
+This prime is: 2^2048 - 2^1984 - 1 + 2^64 * { [2^1918 pi] + 124476 }.
+
+Its hexadecimal value is
+
+.in 6
+FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
+29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
+EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
+E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED
+EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE45B3D
+C2007CB8 A163BF05 98DA4836 1C55D39A 69163FA8 FD24CF5F
+83655D23 DCA3AD96 1C62F356 208552BB 9ED52907 7096966D
+670C354E 4ABC9804 F1746C08 CA18217C 32905E46 2E36CE3B
+E39E772C 180E8603 9B2783A2 EC07A28F B5C55DF0 6F4C52C9
+DE2BCBF6 95581718 3995497C EA956AE5 15D22618 98FA0510
+15728E5A 8AACAA68 FFFFFFFF FFFFFFFF
+.in 3
+
+The generator used with this prime is g = 2. The group order q is
+(p - 1) / 2.
+
+
+
+
+
+.ti 0
+2.5 Key Exchange Status Types
+
+This section defines all key exchange protocol status types that may
+be returned in the SILC_PACKET_SUCCESS or SILC_PACKET_FAILURE packets
+to indicate the status of the protocol. Implementations may map the
+status types to human readable error message. All types except the
+SILC_SKE_STATUS_OK type MUST be sent in SILC_PACKET_FAILURE packet.
+The length of status is 32 bits (4 bytes). The following status types
+are defined:
+
+.in 6
+0 SILC_SKE_STATUS_OK
+
+ Protocol were executed successfully.
+
+
+1 SILC_SKE_STATUS_ERROR
+
+ Unknown error occurred. No specific error type is defined.
+
+
+2 SILC_SKE_STATUS_BAD_PAYLOAD
+
+ Provided KE payload were malformed or included bad fields.
+
+
+3 SILC_SKE_STATUS_UNSUPPORTED_GROUP
+
+ None of the provided groups were supported.
+
+
+4 SILC_SKE_STATUS_UNSUPPORTED_CIPHER
+
+ None of the provided ciphers were supported.
+
+
+5 SILC_SKE_STATUS_UNSUPPORTED_PKCS
+
+ None of the provided public key algorithms were supported.
+
+
+6 SILC_SKE_STATUS_UNSUPPORTED_HASH_FUNCTION
+
+ None of the provided hash functions were supported.
+
+
+7 SILC_SKE_STATUS_UNSUPPORTED_HMAC
+
+ None of the provided HMACs were supported.
+
+
+8 SILC_SKE_STATUS_UNSUPPORTED_PUBLIC_KEY
+
+ Provided public key type is not supported.
+
+
+9 SILC_SKE_STATUS_INCORRECT_SIGNATURE
+
+ Provided signature was incorrect.
+
+
+10 SILC_SKE_STATUS_BAD_VERSION
+
+ Provided version string was not acceptable.
+
+
+11 SILC_SKE_STATUS_INVALID_COOKIE
+
+ The cookie in the Key Exchange Start Payload was malformed,
+ because responder modified the cookie.
+.in 3
+
+
+.ti 0
+3 SILC Connection Authentication Protocol
+
+Purpose of Connection Authentication protocol is to authenticate the
+connecting party with server. Usually connecting party is client but
+server may connect to router server as well. Its other purpose is to
+provide information for the server about which type of connection this
+is. The type defines whether this is client, server or router
+connection. Server use this information to create the ID for the
+connection.
+
+Server MUST verify the authentication data received and if it is to fail
+the authentication MUST be failed by sending SILC_PACKET_FAILURE packet.
+If authentication is successful the protocol is ended by server by sending
+SILC_PACKET_SUCCESS packet.
+
+The protocol is executed after the SILC Key Exchange protocol. It MUST
+NOT be executed in any other time. As it is performed after key exchange
+protocol all traffic in the connection authentication protocol is
+encrypted with the exchanged keys.
+
+The protocol MUST be started by the connecting party by sending the
+SILC_PACKET_CONNECTION_AUTH packet with Connection Auth Payload,
+described in the next section. This payload MUST include the
+authentication data. The authentication data is set according
+authentication method that MUST be known by both parties. If connecting
+party does not know what is the mandatory authentication method it MAY
+request it from the server by sending SILC_PACKET_CONNECTION_AUTH_REQUEST
+packet. This packet is not part of this protocol and is described in
+section Connection Auth Request Payload in [SILC2]. However, if
+connecting party already knows the mandatory authentication method
+sending the request is not necessary.
+
+See [SILC1] and section Connection Auth Request Payload in [SILC2] also
+for the list of different authentication methods. Authentication method
+MAY also be NONE, in which case the server does not require
+authentication. However, in this case the protocol still MUST be
+executed; the authentication data is empty indicating no authentication
+is required.
+
+If authentication method is passphrase the authentication data is
+plaintext passphrase. As the payload is encrypted it is safe to have
+plaintext passphrase. It is also provided as plaintext passphrase
+because the receiver may need to pass the entire passphrase into a
+passphrase verifier, and a message digest of the passphrase would
+prevent this. See the section 3.2.1 Passphrase Authentication for
+more information.
+
+If authentication method is public key authentication the authentication
+data is a digital signature of the hash value of hash HASH and Key
+Exchange Start Payload, established by the SILC Key Exchange protocol.
+This signature MUST then be verified by the server. See the section
+3.2.2 Public Key Authentication for more information.
+
+See the section 4 SILC Procedures in [SILC1] for more information about
+client creating connection to server, and server creating connection
+to router, and how to register the session in the SILC Network after
+successful Connection Authentication protocol.
+
+
+.ti 0
+3.1 Connection Auth Payload
+
+Client sends this payload to authenticate itself to the server. Server
+connecting to another server also sends this payload. Server receiving
+this payload MUST verify all the data in it and if something is to fail
+the authentication MUST be failed by sending SILC_PACKET_FAILURE packet.
+
+The payload may only be sent with SILC_PACKET_CONNECTION_AUTH packet.
+It MUST NOT be sent in any other packet type. The following diagram
+represent the Connection Auth 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 | Connection Type |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| |
+~ Authentication Data ~
+| |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+.in 3
+
+.ce
+Figure 3: Connection Auth Payload
+
+
+.in 6
+o Payload Length (2 bytes) - Length of the entire Connection
+ Auth Payload.
+
+o Connection Type (2 bytes) - Indicates the type of the
+ connection. See section Connection Auth Request Payload
+ in [SILC2] for the list of connection types. This field MUST
+ include valid connection type or the packet MUST be discarded
+ and authentication MUST be failed.
+
+o Authentication Data (variable length) - The actual
+ authentication data. Contents of this depends on the
+ authentication method known by both parties. If no
+ authentication is required this field does not exist.
+.in 3
+
+
+.ti 0
+3.2 Connection Authentication Types
+
+SILC supports two authentication types to be used in the connection
+authentication protocol; passphrase authentication or public key
+authentication based on digital signatures. The following sections
+defines the authentication methods. See [SILC2] for defined numerical
+authentication method types.
+
+
+.ti 0
+3.2.1 Passphrase Authentication
+
+Passphrase authentication or pre-shared key based authentication is
+simply an authentication where the party that wants to authenticate
+itself to the other end sends the passphrase that is required by
+the other end, for example server. The plaintext passphrase is put
+to the payload, that is then encrypted. The plaintext passphrase
+MUST be in UTF-8 [RFC2279] encoding. If the passphrase is in the
+sender's system in some other encoding it MUST be UTF-8 encoded
+before transmitted. The receiver MAY change the encoding of the
+passphrase to its system's default character encoding before verifying
+the passphrase.
+
+If the passphrase matches with the one in the server's end the
+authentication is successful. Otherwise SILC_PACKET_FAILURE MUST be
+sent to the sender and the protocol execution fails.
+
+This is REQUIRED authentication method to be supported by all SILC
+implementations.
+
+When password authentication is used it is RECOMMENDED that maximum
+amount of padding is applied to the SILC packet. This way it is not
+possible to approximate the length of the password from the encrypted
+packet.
+
+
+
+.ti 0
+3.2.2 Public Key Authentication
+
+Public key authentication may be used if passphrase based authentication
+is not desired. The public key authentication works by sending a
+digital signature as authentication data to the other end, say, server.
+The server MUST then verify the signature by the public key of the sender,
+which the server has received earlier in SKE protocol.
+
+The signature is computed using the private key of the sender by signing
+the HASH value provided by the SKE protocol previously, and the Key
+Exchange Start Payload from SKE protocol that was sent to the server.
+These are concatenated and hash function is used to compute a hash value
+which is then signed.
+
+ auth_hash = hash(HASH | Key Exchange Start Payload);
+ signature = sign(auth_hash);
+
+The hash() function used to compute the value is the hash function
+negotiated in the SKE protocol. The server MUST verify the data, thus
+it must keep the HASH and the Key Exchange Start Payload saved during
+SKE and authentication protocols. These values can be discarded after
+Connection Authentication protocol is completed.
+
+If the verified signature matches the sent signature, the authentication
+were successful and SILC_PACKET_SUCCESS is sent. If it failed the
+protocol execution is stopped and SILC_PACKET_FAILURE is sent.
+
+This is REQUIRED authentication method to be supported by all SILC
+implementations.
+
+
+
+.ti 0
+3.3 Connection Authentication Status Types
+
+This section defines all connection authentication status types that
+may be returned in the SILC_PACKET_SUCCESS or SILC_PACKET_FAILURE packets
+to indicate the status of the protocol. Implementations may map the
+status types to human readable error message. All types except the
+SILC_AUTH_STATUS_OK type MUST be sent in SILC_PACKET_FAILURE packet.
+The length of status is 32 bits (4 bytes). The following status types
+are defined:
+
+0 SILC_AUTH_OK
+
+ Protocol was executed successfully.
+
+
+1 SILC_AUTH_FAILED
+
+ Authentication failed.
+
+
+.ti 0
+4 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
+5 References
+
+[SILC1] Riikonen, P., "Secure Internet Live Conferencing (SILC),
+ Protocol Specification", Internet Draft, May 2002.
+
+[SILC2] Riikonen, P., "SILC Packet Protocol", 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.
+
+[RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO
+ 10646", RFC 2279, January 1998.
+
+
+.ti 0
+6 Author's Address
+
+.nf
+Pekka Riikonen
+Snellmaninkatu 34 A 15
+70100 Kuopio
+Finland
+
+EMail: priikone@iki.fi
+
+This Internet-Draft expires XXX
--- /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 XXX
+.ds CH
+.na
+.hy 0
+.in 0
+.nf
+Network Working Group P. Riikonen
+Internet-Draft
+draft-riikonen-silc-pp-07.txt XXX
+Expires: XXX
+
+.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 Internet Draft [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 ......................................... 8
+ 2.3.1 SILC Packet Payloads ................................ 15
+ 2.3.2 Generic payloads .................................... 16
+ 2.3.2.1 ID Payload .................................. 16
+ 2.3.2.2 Argument Payload ............................ 16
+ 2.3.2.3 Channel Payload ............................. 17
+ 2.3.2.4 Public Key Payload .......................... 18
+ 2.3.2.5 Message Payload ............................. 19
+ 2.3.3 Disconnect Payload .................................. 22
+ 2.3.4 Success Payload ..................................... 23
+ 2.3.5 Failure Payload ..................................... 23
+ 2.3.6 Reject Payload ...................................... 24
+ 2.3.7 Notify Payload ...................................... 25
+ 2.3.8 Error Payload ....................................... 32
+ 2.3.9 Channel Message Payload ............................. 33
+ 2.3.10 Channel Key Payload ................................ 34
+ 2.3.11 Private Message Payload ............................ 35
+ 2.3.12 Private Message Key Payload ........................ 36
+ 2.3.13 Command Payload .................................... 38
+ 2.3.14 Command Reply Payload .............................. 39
+ 2.3.15 Connection Auth Request Payload .................... 39
+ 2.3.16 New ID Payload ..................................... 40
+ 2.3.17 New Client Payload ................................. 41
+ 2.3.18 New Server Payload ................................. 42
+ 2.3.19 New Channel Payload ................................ 43
+ 2.3.20 Key Agreement Payload .............................. 43
+ 2.3.21 Resume Router Payload .............................. 44
+ 2.3.22 File Transfer Payload .............................. 45
+ 2.3.23 Resume Client Payload .............................. 46
+ 2.4 SILC ID Types ............................................. 47
+ 2.5 Packet Encryption And Decryption .......................... 48
+ 2.5.1 Normal Packet Encryption And Decryption ............. 48
+ 2.5.2 Channel Message Encryption And Decryption ........... 49
+ 2.5.3 Private Message Encryption And Decryption ........... 50
+ 2.6 Packet MAC Generation ..................................... 50
+ 2.7 Packet Padding Generation ................................. 51
+ 2.8 Packet Compression ........................................ 52
+ 2.9 Packet Sending ............................................ 52
+ 2.10 Packet Reception ......................................... 52
+ 2.11 Packet Routing ........................................... 53
+ 2.12 Packet Broadcasting ...................................... 54
+3 Security Considerations ....................................... 55
+4 References .................................................... 55
+5 Author's Address .............................................. 56
+
+.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: Channel Payload
+Figure 6: Public Key Payload
+Figure 7: Message Payload
+Figure 8: Disconnect Payload
+Figure 9: Success Payload
+Figure 10: Failure Payload
+Figure 11: Reject Payload
+Figure 12: Notify Payload
+Figure 13: Error Payload
+Figure 14: Channel Key Payload
+Figure 15: Private Message Key Payload
+Figure 16: Command Payload
+Figure 17: Connection Auth Request Payload
+Figure 18: New Client Payload
+Figure 19: New Server Payload
+Figure 20: Key Agreement Payload
+Figure 21: Resume Router Payload
+Figure 22: File Transfer Payload
+Figure 23: 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 Internet Draft [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 of the packet and 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) - Is 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 must include private
+ message that is encrypted using private key set by
+ client. Servers does not know anything about this
+ key and this causes that the private message is
+ not handled by the server at all, it is just
+ passed 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 cannot
+ send broadcast packet and normal server cannot send
+ broadcast packet. 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) - Is 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, as a one
+byte, 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 of these 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 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 packet
+description below. 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 below. 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. Client
+ usually does not send this packet.
+
+ Payload of the packet: See section 2.3.3 Disconnect Payload
+
+
+ 2 SILC_PACKET_SUCCESS
+
+ This packet is sent upon successful execution of some protocol.
+ The status of the success is sent in the packet.
+
+ Payload of the packet: See section 2.3.4 Success Payload
+
+
+ 3 SILC_PACKET_FAILURE
+
+ This packet is sent upon failure of some protocol. The status
+ of the failure is sent in the packet.
+
+ Payload of the packet: See section 2.3.5 Failure Payload
+
+
+ 4 SILC_PACKET_REJECT
+
+ This packet MAY be sent upon rejection of some protocol.
+ The status of the rejection is sent in the packet.
+
+ 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 send 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. Channel Keys are distributed by
+ SILC_PACKET_CHANNEL_KEY packet. 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. Each channel has their own independent keys that
+ is used to protect the traffic on the channel. Only server
+ may 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.
+
+ 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.
+
+ 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.
+
+Payloads described in this section are common payloads that MUST be
+accepted anytime during SILC session. Most of the payloads may only
+be sent with specific packet type which is defined in the description
+of the payload.
+
+There are many 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 MUST be 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 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 5: 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 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
+2.3.2.4 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 6: 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
+ public key or certificate data.
+.in 3
+
+
+.ti 0
+2.3.2.5 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 7: 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.
+.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 8: 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 9: 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 10: 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 11: 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. If client
+receives this payload it MAY ignore the contents of the payload, however,
+notify message SHOULD be audited. 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 12: 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 send 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. 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: 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.
+
+ 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.
+
+ 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 must be
+ sent only to the clients which are joined on the channel which
+ topic was set or changed.
+
+ 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.
+
+ 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.
+
+ Max Arguments: 6
+ Arguments: (1) <ID Payload> (2) <mode mask>
+ (3) [<cipher>] (4) <[hmac>]
+ (5) [<passphrase>] (6) [<founder 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.
+
+
+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.
+
+ 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 is sent only
+ when first 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 is
+ joined on the channel.
+
+ 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.
+
+ 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 is
+ sent also 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 notify
+ type is always 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 is sent
+ also to the client which was killed from the network. The client
+ which was killed from the network MUST be removed from the network.
+ This notify type is destined directly to the client which was
+ killed and to channel if the client is on any channel. 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.
+
+ 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 client in case has the SILC_UMODE_REJECT_WATCHING
+user mode 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 totally 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 13: 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
+to make it multiple by eight (8) or multiple by the block size
+of the cipher, which ever is larger.
+
+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 starts 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.
+
+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 14: 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 this key is meant for.
+
+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 private key is used to protect the message, servers between
+the sender and the receiver needs not to decrypt/re-encrypt the
+packet. Section Client To Client in [SILC1] gives example of this
+scheme as well.
+
+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 at any time. 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 15: 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 16: 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. Value zero (0) in this field means that
+ no specific value is set.
+.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 17: 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.
+
+However, 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 18: 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 19: 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 actual Server ID
+ data.
+
+o Server Name Length (2 bytes) - Length of the server name
+ field.
+
+o Server Name (variable length) - The server name.
+.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 key agreement
+is performed outside the SILC network. 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 20: 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 21: 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 22: 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 23: 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.
+
+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, who ever that might
+be. 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. 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 above. 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.
+
+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
+
+This Internet-Draft expires XXX
.nf
Network Working Group P. Riikonen
Internet-Draft
-draft-riikonen-silc-spec-06.txt XXX
+draft-riikonen-silc-spec-07.txt XXX
Expires: XXX
.in 3
3.10.1.2 CTR Mode .................................. 24
3.10.1.3 Randomized CBC Mode ....................... 25
3.10.2 Public Key Algorithms .............................. 26
+ 3.10.2.1 Multi-Precision Integers .................. XXX
3.10.3 Hash Functions ..................................... 26
3.10.4 MAC Algorithms ..................................... 27
3.10.5 Compression Algorithms ............................. 27
computed as described in [PGP].
+.ti 0
+3.10.2.1 Multi-Precision Integers
+
+Multi-Precision (MP) integers in SILC are encoded and decoded as defined
+in PKCS #1 [PKCS1]. MP integers are unsigned, encoded with desired octet
+length. This means that if the octet length is more than the actual
+length of the integer one or more leading zero octets will appear at the
+start of the encoding. The actual length of the integer is the bit size
+of the integer not counting any leading zero bits.
+
+
.ti 0
3.10.3 Hash Functions
projects / silc.git / commitdiff