Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!henry 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