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From: john@hpcvlo.HP.COM (John Eaton)
Newsgroups: sci.crypt
Subject: Re: Completely Secure Encryption
Message-ID: <1290002@hpcvlo.HP.COM>
Date: Fri, 29-May-87 12:24:38 EDT
Article-I.D.: hpcvlo.1290002
Posted: Fri May 29 12:24:38 1987
Date-Received: Mon, 1-Jun-87 05:38:43 EDT
References: <581@gec-mi-at.co.uk>
Organization: Hewlett-Packard Co., Corvallis, OR, USA
Lines: 15

<<<<
<  For better results you should not always start at the first byte of
< the files -- lseek in a random amount.  Depending on your security needs
< you could select a single file that is unchanging, a spelling dictionary
< might be adequate.  What becomes the secret key is where in the file you
< start from.  Either send that information or have a shared, secret function
< that generates the same start position for sender and receiver.

Better results for who? If you have a 100 Mbyte dictionary then you only have
to search through 100 million keys for an exhaustive search. Thats trivial.
Plus the non random nature of a dictionary can also be used to break it.


John Eaton
!hplabs!hp-pcd!john