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From: amolitor@nmsu.edu (Andrew Molitor)
Newsgroups: sci.crypt,alt.security.pgp
Subject: Re: Off the shelf cheap DES keyseach machine (Was: Re: Corporate acceptance of the wiretap chip)
Date: 20 Apr 1993 21:11:26 GMT
Organization: Department of Mathematics
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References: <1993Apr19.093227.1093@jarvis.csri.toronto.edu> <1993Apr20.150531.2059@magnus.acs.ohio-state.edu> <1993Apr20.192105.11751@ulysses.att.com>
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In article <1993Apr20.192105.11751@ulysses.att.com>
	smb@research.att.com (Steven Bellovin) writes:
>
> [ responding to claims about Skipjack cracking engines ]
>
>Thousands?  Tens of thousands?  Do some arithmetic, please...  Skipjack
>has 2^80 possible keys.  Let's assume a brute-force engine like that
>hypothesized for DES:  1 microsecond per trial, 1 million chips.  That's
>10^12 trials per second, or about 38,000 years for 2^80 trials.  Well,
>maybe they can get chips running at one trial per nanosecond, and build
>a machine with 10 million chips.  Sure -- only 3.8 years for each solution.
>

	I think I should also point out that the mystical DES engines
are known plaintext engines (unless you add a ton of really smart
hardware?)

	The 'plaintext' is digitized voice, and exists for a very short
time, probably in a couple inches of copper, tops. It's flatly not
available -- your bug in my office can hear my voice, and even digitize
it, but it's going to get a different bitstream.

	It is horribly naive to suppose that regular folks can figure
out how to crack skipjack, or clipper based telephones. I'm certainly
not devoting a great deal of thought to it.

	Andrew Molitor

