Compression side channel

[Ben Laurie]

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



---------------------------------------------------------------------
The Cryptography Mailing List
Unsubscribe by sending "unsubscribe cryptography" to majordomo at wasabisystems.com