1994-03-29 - Re: Ames/ clipper compromised?

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From: Adam Shostack <adam@bwh.harvard.edu>
To: talon57@well.sf.ca.us (Brian D Williams)
Message Hash: 4c5ec608e9419fd2122b46ef1fbad9d18d1522709ac64a2f389a00e541d76051
Message ID: <199403292157.QAA18896@freud.bwh.harvard.edu>
Reply To: <199403291855.KAA29477@well.sf.ca.us>
UTC Datetime: 1994-03-29 21:58:10 UTC
Raw Date: Tue, 29 Mar 94 13:58:10 PST

Raw message

From: Adam Shostack <adam@bwh.harvard.edu>
Date: Tue, 29 Mar 94 13:58:10 PST
To: talon57@well.sf.ca.us (Brian D Williams)
Subject: Re: Ames/ clipper compromised?
In-Reply-To: <199403291855.KAA29477@well.sf.ca.us>
Message-ID: <199403292157.QAA18896@freud.bwh.harvard.edu>
MIME-Version: 1.0
Content-Type: text/plain

The skipjack review committe wrote:

| 3.  Susceptibility to Brute Force Attack by Exhaustive Search
| An implementation of  SKIPJACK optimized for a single processor on
| the 8-processor Cray YMP performs about 89,000 encryptions per
| second.  At that rate, it would take more than 400 billion years to
| try all keys. Assuming the use of all 8 processors and aggressive
| vectorization, the time would be reduced to about a billion years

	Could someone explain why jumping to 8 processors knocks the
time down by a factor of 400, instead of a factor of 8?  Is the 400
billion years a load of crap, intended to sound more impressive than


Adam Shostack 				       adam@bwh.harvard.edu

Politics.  From the greek "poly," meaning many, and ticks, a small,
annoying bloodsucker.

Have you signed the anti-Clipper petition?