Columbia crypto box

[Bill Frantz]

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
(408)356-8506         | used to be the Ameican | 16345 Englewood Ave.
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