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Re: Whatever happend to compression?
>>>>> "Perry" == Perry E Metzger <perry@piermont.com> writes:
Perry> Matt Holdrege/Ascend/US writes:
>> A few thoughts.
>>
>> In general, compression is nice in that it randomizes the data
>> first, then encryption further scrambles the bits making it
>> harder for anyone to make sense of it. It's another roadblock
>> to the bad guy.
Perry> Any compression scheme you can reverse doesn't randomize
Perry> the data in any meaningful sense. The reason to want
Perry> compression is to reduce bandwidth, not for security.
Compression reduces the redundancy of the plaintext and increases the
unicity distance of the cypher [1, p. 12]. This makes the cryptogram
both smaller and stronger.
[1] "Contemporary Cryptography: An Introduction" by James L. Massey
(reprinted from "Contemporary Cryptography: the Science of Information
Integrity" G.J. Simmons, editor. IEEE Press, 1991), in "Cryptography
and Data Protection" J.H. van Lint and R. Tijdeman, editors,
Konninklijke Nederlandse Akademie van Wetenshappen Verhandelingen,
1992.
--
Joe Konczal <joseph.konczal@nist.gov>
National Institute of Standards and Technology
Building 820, Room 410 Phone: (301) 975-3285
Gaithersburg, MD 20899 USA Fax: (301) 948-0279
References: