From: an41418@anon.penet.fi (wonderer)
Date: Mon, 11 Oct 93 16:16:23 PDT
To: cypherpunks@toad.com
Subject: Re: Breaking DES
Message-ID: <9310112312.AA12510@anon.penet.fi>
MIME-Version: 1.0
Content-Type: text/plain


I am sorry to have asked two questions in my original
post. A few people have made me aware of the reason
for encrypting EDE in triple DES for backward compatability
and the issue of whether or not DES is a group.
So, I'd like to redirect this thread to my other
question:

         My understanding of how an exhaustive search on the key space
         can be used to break DES is that for every key, K, D(K,Cipher)
         is applied until the output matches something legible.

         Say that some random string, to be thrown out, is added
         to the beginning of the plain text, and that DES is applied
         in cbc mode, then how could such an attack work?

         My point, I don't see how DES can be broken if the initial
         block is a grabage block, and cipher block chaining is used.
         Please enlighten me (gently).

Wonderer
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