Columbia crypto box

Trei, Peter ptrei at
Thu Feb 13 11:08:45 EST 2003

> Pete Chown[SMTP:Pete.Chown at]
> Arnold G. Reinhold wrote:
> > Indeed, but it is important to remember just how thickheaded the 
> > anti-crypto effort of the '80s and '90s was and how much damage it did.
> As a footnote to those times, 2 ** 40 is 1,099,511,627,776.  My PC can 
> do 3,400,000 DES encryptions per second (according to openssl).  I 
> believe DES key setup is around the same cost as one encryption, so we 
> should halve this if a different key is being used each time.  Brute 
> force of a 40-bit DES key will therefore take about a week.  In other 
> words 40-bit DES encryption is virtually useless, as brute force would 
> be available to anyone with a modern PC.
> -- 
> Pete
You can actually do much better that that for key set up. To toot my own
horn, one of the critical events in getting software DES crackers running 
at high speed was my realization that single-bit-set key schedules can
be OR'd together to produce any key's schedule. Combining this with
the use of Grey Codes to choose the order in which keys were tested
(Perry's idea) led to key scheduling taking about 5% of the time budget.


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