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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: sci.crypt
Subject: Re: VC2000 "Update"
Message-ID: <7507@utzoo.UUCP>
Date: Sat, 10-Jan-87 21:18:04 EST
Article-I.D.: utzoo.7507
Posted: Sat Jan 10 21:18:04 1987
Date-Received: Sat, 10-Jan-87 21:18:04 EST
References: <3806@utcsri.UUCP> <1207@frog.UUCP>, <668@cartan.Berkeley.EDU>
Organization: U of Toronto Zoology
Lines: 19

> >Some time ago, Shamir (I think) demonstrated that
> >DES was untrustworthy by concocting a similar encryption scheme...
> >then he showed ... the trapdoor hidden in the tables.  Thus, the belief that
> >DES _can_ have no trapdoor is undermined.
> 
>    This is, I believe, false.  It is true that many people have tried to do
> this, but no such successful effort has been reported.

The statement is true despite the lack of success in finding a DES trapdoor.
Read the original comment carefully, please:  the question is not whether
DES has a trapdoor -- nobody except, possibly, NSA knows -- but whether it
*could plausibly* have a trapdoor.  The construction of a superficially-
secure DES-like system with a hard-to-find trapdoor demonstrates that such
systems can have trapdoors that are difficult to find.  Combined with the
continuing unwillingness of NSA to permit disclosure of the design principles
underlying parts of DES, it's not proof but it is suspicious.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,decvax,pyramid}!utzoo!henry