Frequently Asked Questions


Q: What is SILC?
A: SILC (Secure Internet Live Conferencing) is a protocol which provides
   secure conferencing services in the Internet over insecure channel.
   SILC is IRC like although internally they are very different.  Biggest
   similiarity between SILC and IRC is that they both provide conferencing
   services and that SILC has almost same commands as IRC.  Other than
   that they are nothing alike.

   Biggest differences are that SILC is secure what IRC is not in any
   way.  The network model is also entirely different compared to IRC.


Q: Can I use SILC with IRC client?  What about can I use IRC with SILC
   client?
A: Answer for both question is no.  IRC client is in no way compatible
   with SILC server.  SILC client cannot currenly use IRC but this may
   change in the future if IRC support is added to the SILC client.  
   After that one could use both SILC and IRC with the same client.
   Although, even then one cannot talk from SILC network to IRC network.
   That just is not possible.


Q: How secure SILC really is?
A: A good question which I don't have a answer.  SILC has been tried to
   make as secure as possible.  However, there is no security protocol
   or security software that has not been vulnerable to some sort of
   attacks.  SILC is in no means different from this.  So, it is suspected 
   that there are security holes in the SILC.  These holes just needs to 
   be found so that they can be fixed.

   But to give you some parameters of security SILC uses the most secure
   crytographic algorithms such as Blowfish, RC5, Twofish, etc.  SILC
   does not have DES or 3DES as DES is insecure and 3DES is just too
   slow.  SILC also uses cryptographically strong random number generator
   when it needs random numbers.  Public key cryptography uses RSA
   and Diffie Hellman algorithms.  Key lengths for ciphers are initially
   set to 128 bits but many algorithm supports longer keys.  For public
   key algorithms the starting key length is 1024 bits.

   But the best answer for this question is that SILC is as secure as
   its weakest link.  SILC is open and the protocol is open and in public
   thus open for security analyzes.

   To give a list of attacks that are ineffective against SILC:

      o Man-in-the-middle attacks are ineffective if proper public key
        infrastructure is used.  SILC is vulnerable to this attack if
        the public keys used in the SILC are not verified to be trusted.

      o IP spoofing is ineffective (because of encryption and trusted 
        server keys).

      o Attacks that change the contents of the data or add extra
        data to the packets are ineffective (because of encryption and
        integrity checks).

      o Passive attacks (listenning network traffic) are ineffective
        (because of encryption).  Everything is encrypted including
        authentication data such as passwords when they are needed.

      o Any sort of cryptanalytic attacks are tried to make ineffective
        by using the best cryptographic algorithms out there.


Q: Why SILC? Why not IRC3?
A: Question that is justified no doubt of that.  I didn't start doing SILC
   to be replacement for IRC.  SILC was something that didn't exist in
   1996 or even today except that SILC is now released.  However, I did
   check out the IRC3 project in 1997 when I started coding and planning
   the SILC protocol.

   But, IRC3 is problematic. Why? Because it still doesn't exist.  The
   project is at the same spot where it was in 1997 when I checked it out.
   And it was old project back then as well.  Couple of months ago I 
   checked it again and nothing were happening.  That's the problem of IRC3
   project.  The same almost to happened to SILC as well as I wasn't making
   real progress over the years.  I talked to the original author of IRC,
   Jarkko Oikarinen, in 1997 and he directed me to the IRC3 project, 
   although he said that IRC3 is a lot of talking and not that much of 
   anything else.  I am not trying to put down the IRC3 project but its
   problem is that no one in the project is able to make a decision what
   is the best way to go about making the IRC3 and I wasn't going to be
   part of that.  The fact is that if I would've gone to IRC3 project,
   nor IRC3 or SILC would exist today.  I think IRC3 could be something
   really great if they just would get their act together and start
   coding the thing.  I hope that the release of SILC gives a boost to
   the IRC3 project as well.