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From: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.org.eff.talk,sci.crypt
Subject: Re: Vendor's Responsibilities on seized equipments
Keywords: what to do, authorities, etc..
Message-ID: <20254:Jan1017:19:1891@kramden.acf.nyu.edu>
Date: 10 Jan 91 17:19:18 GMT
References: <13899@uudell.dell.com> <1991Jan10.041906.27901@ddsw1.MCS.COM>
Organization: IR
Lines: 12

In article <1991Jan10.041906.27901@ddsw1.MCS.COM> karl@ddsw1.MCS.COM (Karl Denninger) writes:
> A key is used to encipher each byte.  After each byte is ciphered, the key 
> is permuted, and depending on the results of that permutation a random number
> of bytes of "garbage" (random data) from 0-n is added to the output file.

I assume you do this after compression so that the original data doesn't
have any immediately noticeable redundancy. Then this system is secure
if and only if the ``random number'' is cryptographically secure and the
``garbage'' is both random and independent of the key. I find the first
assumption exceedingly unlikely.

---Dan