[9241] in cryptography@c2.net mail archive
Re: Compression side channel
daemon@ATHENA.MIT.EDU (Ben Laurie)
Mon Sep 10 10:52:43 2001
Message-ID: <3B9C860F.DDB7FD95@algroup.co.uk>
Date: Mon, 10 Sep 2001 10:21:19 +0100
From: Ben Laurie <ben@algroup.co.uk>
MIME-Version: 1.0
To: Bill Stewart <bill.stewart@pobox.com>
Cc: Greg Rose <ggr@qualcomm.com>, Sandy Harris <sandy@storm.ca>,
cryptography@wasabisystems.com
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Bill Stewart wrote:
>
> At 11:11 AM 09/10/2001 +1000, Greg Rose wrote:
> >At 12:44 AM 9/9/2001 -0400, Sandy Harris wrote:
> >>Does using non-adaptive compression save the day?
> >
> >Huffman coding using a fixed code table is not a bad way to go. You can
> >even peek at the characteristics of the input and choose a table based on
> >that... having standardised tables for English text, intel machine code,
> >MS-word documents, C code, other languages, etc. Fax machines do something
> >like this, with a huffman code table conditioned on a set of standard
> >documents, but I'm not sure whether it is just a single table or a set of
> >"choose one of these".
>
> G3 is a single table - it's the standard used for most fax machines,
> with 100x200 or 200x200 resolution.
> Not sure about G4, which has higher resolution,
> but I think that's the case for it also.
G4 includes ways to repeat the previous line with minor modifications,
but still uses Huffman encoding.
Cheers,
Ben.
--
http://www.apache-ssl.org/ben.html
"There is no limit to what a man can do or how far he can go if he
doesn't mind who gets the credit." - Robert Woodruff
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