Re: well braid

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Article #791

#791

From: Ross Anderson
Date: Tue, 18 Aug 1992 10:54

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In <13989@elevia.uniforum.qc.ca>, alain@elevia.uniforum.qc.ca (W.A.Simon)
writes:

> The proposed system works by multiplexing (braiding) two or more bit
> streams.  Depending on the value of key bits, the next bit of output
> is taken from one or the other input.

Something similar has been around in the world of stream ciphers since
about 1980. It was demolished in

`Solving a class of stream ciphers', Cryptologia vol XIV no 3 (July 1990)
pp 285 - 288. 

As far as I can see, your system will have to be modified to withstand 
this kind of attack.

Hope this helps

Ross

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Path: arc1-ca.pugleaf.net!sparky!uunet!mcsun!uknet!cam-cl!cam-cl!rja14
From: rja14@cl.cam.ac.uk (Ross Anderson)
Newsgroups: sci.crypt
Subject: Re: well braid
Message-ID: <1992Aug18.105437.4617@cl.cam.ac.uk>
Date: 18 Aug 92 10:54:37 GMT
References: <13989@elevia.uniforum.qc.ca>
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Organization: U of Cambridge Computer Lab, UK
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