Re: Any truth to rumor that NSA had Public Key Crypto first?

From: Bernie Cosell (bernie_at_fantasyfarm.com)
Date: 09/29/04 

Date: Wed, 29 Sep 2004 10:52:30 -0400

unruh@string.physics.ubc.ca (Bill Unruh) wrote:

} No, that is not what he says. He says that NIST asked for a public
} encryption standard. NSA probably did not want to give them a private one
} precisely because they did not want to reveal their state. They weakened
} DES by making the key short, and strengthened it with the Sbox design.
} Basically this meant only they had a chance of breaking it. (good Sbox so
} only exhaustive search works, short key so that they but not others could
} actually carry out exhaustive search.)

Perhaps I'm not understanding, quite, but I thought that shortening the key
*did*not* weaken DES. Giving DES a much longer key than they actually did
would have been *false*security*, since there are brute-force techniques
[that I assume NSA knew even if we civilians didn't at the time] for
cracking it that ran only at what, 2^52 or the like..

I guess what I'm saying is that if there are two paths of attack on a
ciphersystem and one is of a particular difficulty it adds NO security to
the ciphersystem to make the _other_ one extremely strong. If your back
door is a screen door, it doesn't make any difference how many locks you
put on the front door...

  /Bernie\ 

-- 
Bernie Cosell                     Fantasy Farm Fibers
bernie@fantasyfarm.com            Pearisburg, VA
    -->  Too many people, too few sheep  <--

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