Columbia crypto box

Bill Frantz frantz at
Wed Feb 12 01:43:54 EST 2003

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:

Cheers - Bill

Bill Frantz           | Due process for all    | Periwinkle -- Consulting
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