From: "geeman@best.com" <geeman@best.com>
Date: Sat, 5 Oct 1996 05:09:22 +0800
To: "'Gary Howland'" <gary@systemics.com>
Subject: RE: DESCrack keyspace partitioning
Message-ID: <01BBB1D1.92DA93A0@geeman.vip.best.com>
MIME-Version: 1.0
Content-Type: text/plain


Re: DESCrack keyspace partitioning

geeman@best.com wrote:
> 
> What about the heuristics of partitioning the keyspace?
> 
> Seems to me that a _subset_ of all possible keys is much more likely
> to appear than a random selection from an equidistributed population 0..2^56.
> 
> (P)RNG's just aren't that likely to produce a key of 010101010.....
> nor 001100110011...

Why?  They seem just as likely as any other sequence.

I left out a piece: again heuristically speaking, most DES keys are derived from pasword hash, or
similar technique.  In such a case the statistics of the generated keys are (it looks like) _highly_
skewed.

 etc etc and I have been thinking about how one might formalize
> and exploit this randomness property to increase the probability of finding the key sooner.

Again, which randomness property?

The property that essentially _no_ predictability is found in a hash-derived key.

Gary
--
"Of course the US Constitution isn't perfect; but it's a lot better
than what we have now."  -- Unknown.

pub  1024/C001D00D 1996/01/22  Gary Howland <gary@systemics.com>
Key fingerprint =  0C FB 60 61 4D 3B 24 7D  1C 89 1D BE 1F EE 09 06