From: Linn Stanton <lstanton@sten.lehman.com>
Date: Wed, 27 Jul 94 07:05:39 PDT
To: cypherpunks@toad.com
Subject: Re: CYPHERPUNKS TO THE RESCUE
In-Reply-To: <9407261944.AA04628@smds.com>
Message-ID: <9407271406.AA00426@sten.lehman.com>
MIME-Version: 1.0
Content-Type: text/plain


In message <9407261944.AA04628@smds.com> FutureNerd Steve Witham writes:
  > But this raises an idle question: how much easier is it to break 
  > a DES key given a sequence of (n, DES(n)) where the n's are 
  > successive numbers, than it is if the n's are random (but still
  > known)?  I doubt this is a practical threat for garage doors.

This would be a known plaintext attack, well suited to differential
cryptanalysis.

Though the lifetime of the average garage door opener is probably small
enough that it would die before you had enough plaintext/ciphertext
pairs for a good attack