Re: Wikipedia "Cryptography" reaches Featured Article status

"David Wagner" <daw@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
The claim is that they knew DC at relatively the same level of
sophistication as the public eventually learned in 1990.
Coppersmith never said that. I suspect you're misremembering what was
in his paper. Coppersmith says that the IBM team knew the basic
principles
of DC, but he never claimed that they knew everything the public
eventually
knew about DC. It's clear that other researchers later refined DC beyond
what IBM knew, and I don't think Coppersmith ever disputed that.
Coppersmith didn't claim what you are saying he claimed.

Coppersmith suggests it strongly enough that Levy could have
believed it. Coppersmith says in his paper:

History and discussion
Differential cryptanalysis was not known in the open
literature until quite recently. ... In 1990, Sean Murphy
published the method ... This was soon followed by several
papers of Biham and Shamir, ... Differential cryptanalysis
was well known, however, to the IBM team that designed DES,
as early as 1974.
http://www.research.ibm.com/journal/rd/383/coppersmith.pdf

This suggests that IBM knew in 1974 what Biham-Shamir
published in 1991. I think that Tom is right that IBM did not
know nearly that much.


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