From: "geeman@best.com" <geeman@best.com>
Date: Sat, 5 Oct 1996 05:29:16 +0800
To: "'m5@tivoli.com>
Subject: RE: DESCrack keyspace partitioning
Message-ID: <01BBB1D1.94D09740@geeman.vip.best.com>
MIME-Version: 1.0
Content-Type: text/plain


Another thinking step: most real-world DES keys are derived from hashes.
Not (P)RNGs.
The distributions are **not** uniform.
I am talking about FAMILIES of predictable bit patterns in keys, not any specific pattern.
I'm doing the stats.

The goal is to search the most likely keys first, and 
not all keys are created equally.

Your reasoning is thin.


----------
From: 	Mike McNally[SMTP:m5@tivoli.com]
Sent: 	Friday, October 04, 1996 6:10 AM
To: 	geeman@best.com
Cc: 	'cypherpunks@toad.com'
Subject: 	Re: DESCrack keyspace partitioning

geeman@best.com wrote:
>
> (P)RNG's just aren't that likely to produce a key of 010101010.....
> nor 001100110011... etc etc 

Right.  A good CSPRNG is ulikely to produce the pattern 010101010101.
It's also unlikely to produce the pattern 0011001100110011.  Oh, and
it's also unlikely to produce 01100100101001011.  In fact, a good
32-bit CSPRNG has only a 1/2^32 chance of producing any particular
bit pattern.  Of course, another way of saying that is that it's just
as likely to get an "obvious" bit pattern as it is to get any other
one.  You can't just throw away part of the keyspace based on such
bogus reasoning.  (There may be other reasons to throw away part of
the keyspace, of course.)

______c_________________________________________________________________
Mike M Nally * IBM % Tivoli * Austin TX  * How quickly we forget that
mailto:m5@tivoli.com mailto:m101@io.com  * "deer processing" and "data
http://www.io.com/~m101/                 * processing" are different!