Question: OTP

paul at fatmans.demon.co.uk paul at fatmans.demon.co.uk
Mon Oct 21 09:48:39 PDT 1996



> This whole thing seems crazier each time I think about it.
> basically my question is: given that he picks his key securly does he have
> an OTP if the plaintext is shorter than the key?
> Bob

Yes, if he were just to modular add the key to the plaintext (or XOR 
them) he would have an OTP if AND ONLY IF the key were real random, 
however, he doesn`t do this, he uses the key to seed an array or 
linear congruential generators, which have been cryptanalysed to hell 
and back.

Basically, ALWAYS, and I mean ALWAYS dismiss anyone trying to sell an 
OTP, they are totally impractical, he`s just using technobabble to 
get around the fact that his system is actually a stream cipher and 
is of no value because it has been broken within days of being 
announced.



 

  Datacomms Technologies web authoring and data security
       Paul Bradley, Paul at fatmans.demon.co.uk
  Paul at crypto.uk.eu.org, Paul at cryptography.uk.eu.org    
       Http://www.cryptography.home.ml.org/
      Email for PGP public key, ID: 5BBFAEB1
     "Don`t forget to mount a scratch monkey"






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