[9242] in cryptography@c2.net mail archive
Re: Compression side channel
daemon@ATHENA.MIT.EDU (Ben Laurie)
Mon Sep 10 10:54:17 2001
Message-ID: <3B9C8671.B00C4635@algroup.co.uk>
Date: Mon, 10 Sep 2001 10:22:57 +0100
From: Ben Laurie <ben@algroup.co.uk>
MIME-Version: 1.0
To: Greg Rose <ggr@qualcomm.com>
Cc: Sandy Harris <sandy@storm.ca>, cryptography@wasabisystems.com
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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".
Choosing one of a set of tables would be a bad idea - I can then use the
chosen plaintext to force the choice of particular tables, which would
then leak information copiously.
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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