[12515] in cryptography@c2.net mail archive
Re: Columbia crypto box
daemon@ATHENA.MIT.EDU (Bill Frantz)
Wed Feb 12 12:13:15 2003
X-Original-To: cryptography@wasabisystems.com
X-Original-To: cryptography@wasabisystems.com
Date: Tue, 11 Feb 2003 22:43:54 -0800
To: cryptography@wasabisystems.com
From: Bill Frantz <frantz@pwpconsult.com>
I wrote:
>(IIRC, basically what the device did was reveal 16 bits of a DES key.)
It has been pointed out to me that they were even more clever than that.
(This technique could allow a dictionary attack on known/probable plain
text.) What they did instead was, take a 56 bit DES key through a one way function, zero certain bits so only 40 are variable, take the result through another one way function, and use the result as a DES key for encryption.
For details see US patent 5,323,464: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/search-bool.html&r=47&f=G&l=50&co1=AND&d=ptxt&s1=Matyas.INZZ.&OS=IN/Matyas&RS=IN/Matyas
Cheers - Bill
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Bill Frantz | Due process for all | Periwinkle -- Consulting
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