From: tcmay@sensemedia.net (Timothy C. May)
Date: Wed, 19 Jul 95 09:14:53 PDT
To: "Douglas B. Renner" <cypherpunks@toad.com
Subject: Re: Stego-Rants ?
Message-ID: <ac327d250c021004491e@[205.199.118.202]>
MIME-Version: 1.0
Content-Type: text/plain


At 7:57 AM 7/19/95, Douglas B. Renner wrote:
>Just a few thoughts:
>
>1. Use the randomness in a computer generated piece of English text to
>hold your real message, encrypted, and obscured.
>
>2. Even more entertaining would be if the foreground text could somehow
>be contrived to be meaningful. I know this would be a "good trick" but
>I'd conjecture that it's possible.  Imagine fractal compression of a text
>file, with the decompression routine adding some "randomness" which would
>be your message, obscured at a very abstract level.  Depending on how
>much "randomness" was added, I'm wondering if the resulting text might
>possibly retain some of its original legibility (?)  I am assuming that
>a companion fractal re-compressing routine would be required to retrieve
>the cypher.
>
>(I am looking at an ad for a graphics program, "Images Incorporated" by
>Iterated Systems which with fractal techniques can achieve 100:1
>compression -- and then -- decompress to 8 times the original bitmap size
>with minimal added distortion.)

But fractal compression schemes are usually _lossy_, that is, some of the
original bits are irretrievably lost. (This should be clear also from the
amount of compression achieved....multiple files/images compress to the
"same" smaller file--by the "pigeonhold principle.")

Lossy compression is often OK for visual images and audible files, a la
music, but would be pretty bad for any scheme dependent on encryption.

(Not totally out of the question, as error correction could be used to
maybe  construct the critical bits, but then there's a messy battle going
on between lossy compresssion to get more bit density and adding bits for
error correction...)

--Tim May

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