.ds RF FORMFEED[Page %]
.ds CF
.ds LH Internet Draft
-.ds RH XXX
+.ds RH 15 May 2002
.ds CH
.na
.hy 0
.nf
Network Working Group P. Riikonen
Internet-Draft
-draft-riikonen-silc-spec-05.txt XXX
-Expires: XXX
+draft-riikonen-silc-spec-05.txt 15 May 2002
+Expires: 15 November 2002
.in 3
3.2.2 Server ID ........................................... 11
3.2.3 SILC Server Ports ................................... 12
3.3 Router .................................................... 12
- 3.3.1 Router's Local ID List .............................. 12
+ 3.3.1 Router's Local ID List .............................. 13
3.3.2 Router's Global ID List ............................. 13
3.3.3 Router's Server ID .................................. 14
3.4 Channels .................................................. 14
- 3.4.1 Channel ID .......................................... 16
+ 3.4.1 Channel ID .......................................... 15
3.5 Operators ................................................. 16
3.6 SILC Commands ............................................. 16
3.7 SILC Packets .............................................. 17
3.8 Packet Encryption ......................................... 17
- 3.8.1 Determination of the Source and the Destination ..... 17
+ 3.8.1 Determination of the Source and the Destination ..... 18
3.8.2 Client To Client .................................... 18
- 3.8.3 Client To Channel ................................... 19
+ 3.8.3 Client To Channel ................................... 20
3.8.4 Server To Server .................................... 20
3.9 Key Exchange And Authentication ........................... 20
- 3.9.1 Authentication Payload .............................. 20
- 3.10 Algorithms ............................................... 22
- 3.10.1 Ciphers ............................................ 22
- 3.10.2 Public Key Algorithms .............................. 23
+ 3.9.1 Authentication Payload .............................. 21
+ 3.10 Algorithms ............................................... 23
+ 3.10.1 Ciphers ............................................ 23
+ 3.10.2 Public Key Algorithms .............................. 24
3.10.3 Hash Functions ..................................... 24
- 3.10.4 MAC Algorithms ..................................... 24
+ 3.10.4 MAC Algorithms ..................................... 25
3.10.5 Compression Algorithms ............................. 25
- 3.11 SILC Public Key .......................................... 25
- 3.12 SILC Version Detection ................................... 27
+ 3.11 SILC Public Key .......................................... 26
+ 3.12 SILC Version Detection ................................... 28
3.13 Backup Routers ........................................... 28
- 3.13.1 Switching to Backup Router ......................... 29
- 3.13.2 Resuming Primary Router ............................ 30
- 3.13.3 Discussion on Backup Router Scheme ................. 32
-4 SILC Procedures ............................................... 33
- 4.1 Creating Client Connection ................................ 33
- 4.2 Creating Server Connection ................................ 34
- 4.2.1 Announcing Clients, Channels and Servers ............ 35
- 4.3 Joining to a Channel ...................................... 36
- 4.4 Channel Key Generation .................................... 37
- 4.5 Private Message Sending and Reception ..................... 38
- 4.6 Private Message Key Generation ............................ 38
- 4.7 Channel Message Sending and Reception ..................... 39
- 4.8 Session Key Regeneration .................................. 39
- 4.9 Command Sending and Reception ............................. 40
- 4.10 Closing Connection ....................................... 41
- 4.11 Detaching and Resuming a Session ......................... XXXXX
-5 Security Considerations ....................................... 41
-6 References .................................................... 42
-7 Author's Address .............................................. 44
+ 3.13.1 Switching to Backup Router ......................... 30
+ 3.13.2 Resuming Primary Router ............................ 31
+ 3.13.3 Discussion on Backup Router Scheme ................. 33
+4 SILC Procedures ............................................... 34
+ 4.1 Creating Client Connection ................................ 34
+ 4.2 Creating Server Connection ................................ 35
+ 4.2.1 Announcing Clients, Channels and Servers ............ 36
+ 4.3 Joining to a Channel ...................................... 37
+ 4.4 Channel Key Generation .................................... 38
+ 4.5 Private Message Sending and Reception ..................... 39
+ 4.6 Private Message Key Generation ............................ 39
+ 4.7 Channel Message Sending and Reception ..................... 40
+ 4.8 Session Key Regeneration .................................. 40
+ 4.9 Command Sending and Reception ............................. 41
+ 4.10 Closing Connection ....................................... 42
+ 4.11 Detaching and Resuming a Session ......................... 42
+5 Security Considerations ....................................... 44
+6 References .................................................... 45
+7 Author's Address .............................................. 47
not equivalent to IRC and does not support IRC. Some of the SILC's
features are not found in IRC but in traditional Instant Message (IM)
protocols. SILC combines features from both of these chat protocol
-styles, and SILC can be implemeneted as either IRC-like system or
+styles, and SILC can be implemented as either IRC-like system or
IM-like system.
Strong cryptographic methods are used to protect SILC packets inside
document and protocol. [SILC2] also describes the packet encryption
and decryption in detail. The SILC Packet Protocol provides secured
and authenticated packets, and the protocol is designed to be compact.
-This makes SILC also suitable in environment of low bandwith
+This makes SILC also suitable in environment of low bandwidth
requirements such as mobile networks. All packet payloads in SILC
can be also compressed.
are in the center of the cell and servers are connected to the router.
-
-
-
-
-
The following diagram represents SILC network topology.
.in 8
represents message sending between cells.
+
+
+
.in 16
.nf
1 --- S1 S4 --- 5 S2 --- 1
must not routers use each other as their primary routes. The router
connections in the network must form a ring.
-
-
-
-
-
-
Example with three routers in the network:
Also, if any other router in the network is using the cell's primary
router as its own primary router, it must also have passive connection
to the cell's backup router. It too is prepared to switch to use the
-backup router as its new primary router as soon as the orignal primary
+backup router as its new primary router as soon as the original primary
router becomes unresponsive.
All of the parties of this protocol knows which one is the backup router
backup router. The backup router usually needs to do local modifications
to its database in order to update all the information needed to maintain
working routes. The backup router must understand that clients that
-were orignated from the primary router are now originated from some of
+were originated from the primary router are now originated from some of
the existing server connections and must update them accordingly. It
must also remove those clients that were owned by the primary router
since those connections were lost when the primary router became
3.13.2 Resuming Primary Router
Usually the primary router is unresponsive only a short period of time
-and it is intended that the original router of the cell will reassume
+and it is intended that the original router of the cell will resume
its position as primary router when it comes back online. The backup
router that is now acting as primary router of the cell must constantly
try to connect to the original primary router of the cell. It is
3.13.3 Discussion on Backup Router Scheme
It is clear that this backup router support is not able to handle all
-possible situations arrising in unreliable network environment. This
+possible situations arising in unreliable network environment. This
scheme for example does not handle situation when the router actually
does not go offline but the network link goes down temporarily. It would
require some intelligence to figure out when it is best time to switch
it should have cached the Client ID from the SILC Packet Header.
If server receives a private message packet which includes invalid
-destionation Client ID the server MUST send SILC_NOTIFY_TYPE_ERROR
+destination Client ID the server MUST send SILC_NOTIFY_TYPE_ERROR
notify to the client with error status indicating that such Client ID
does not exist.
channel message destined explicitly to a client on the channel.
If server receives a channel message packet which includes invalid
-destionation Channel ID the server MUST send SILC_NOTIFY_TYPE_ERROR
+destination Channel ID the server MUST send SILC_NOTIFY_TYPE_ERROR
notify to the sender with error status indicating that such Channel ID
does not exist.
-See the [SILC2] for description of channel messege routing for router
+See the [SILC2] for description of channel message routing for router
servers, and channel message encryption and decryption process.
are running the service. It is recommended that some form of registration
is required by the server and router administrator prior acceptance to
the SILC Network. Even though, the SILC protocol is secure in a network
-of mutual distrust between clients, servers, routers and adminstrators
+of mutual distrust between clients, servers, routers and administrators
of the servers, the client should be able to trust the servers they are
-using if they whish to do so.
+using if they wish to do so.
It however must be noted that if the client requires absolute security
by not trusting any of the servers or routers in the SILC Network, it can
messages, private messages and channel messages.
It is important to note that SILC, like any other security protocol is
-not full proof system and cannot secure from insecure environment; the
-SILC servers and routers could very well be compromised. However, to
-provide acceptable level of security and usability for end user the
-protocol use many times session keys or other keys generated by the
-servers to secure the messages. This is intentional design feature to
-allow ease of use for end user. This way the network is still usable,
-and remains encrypted even if the external means of distributing the
-keys is not working. The implementation, however, may like to not
-follow this design feature, and always negotiate the keys outside SILC
-network. This is acceptable solution and many times recommended. The
-implementation still must be able to work with the server generated keys.
+not full proof system; the SILC servers and routers could very well be
+compromised. However, to provide acceptable level of security and
+usability for end user the protocol use many times session keys or other
+keys generated by the servers to secure the messages. This is
+intentional design feature to allow ease of use for end user. This way
+the network is still usable, and remains encrypted even if the external
+means of distributing the keys is not working. The implementation,
+however, may like to not follow this design feature, and always negotiate
+the keys outside SILC network. This is acceptable solution and many times
+recommended. The implementation still must be able to work with the
+server generated keys.
If this is unacceptable for the client or end user, the private keys
-negotiatied outside the SILC Network should always be used. In the end
+negotiated outside the SILC Network should always be used. In the end
it is always implementor's choice whether to negotiate private keys by
default or whether to use the keys generated by the servers.
.nf
Pekka Riikonen
-Snellmanninkatu 34 A 15
+Snellmaninkatu 34 A 15
70100 Kuopio
Finland
EMail: priikone@iki.fi
-This Internet-Draft expires XXX
+This Internet-Draft expires 15 November 2002
projects / runtime.git / blobdiff