Re: [Algorithms] Message signature in token ring

[Dave M. <dm...@od...>]

Space Needle Exchange Program wrote:
> 
[...]
> know. But you can explain more what you meant by "RSA's minimum
> message length is the length of the modulus"?

  Here's a concise description of the algorithm. 
http://www.pvv.ntnu.no/~asgaut/crypto/thesis/node18.html.  In step 4,
you can see that the ciphertext is going to be a number between 0 and
PQ, the modulus.  For secure moduli sizes, (512 bits for security
against a college student with access to a campus full of computers)
this is a pretty large overhead, which is why products like PGP use
public key algorithms only to transport keys for symmetric algorithms. 
256 bits is a really low number for RSA.  It's about an 80 digit number
which could be factored probably in a couple of days by someone who had
access to just a few decent computers.

  Honestly, you should forget about all of this.  You'll get it wrong. 
This is not a statement about your coding skills, because EVERYONE gets
it wrong.  Security is a REALLY hard problem to solve correctly, and
you've got just about the hardest case there is.  (P2P, no authoritative
server, minimal precommunication between peers, full executable
available to hackers, packets explicitly handed to people for
man-in-the-middle attacks.)  Your time is much better spent making a
game that people want to hack... :)

					...dave