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1996-10-04 - Re: DESCrack keyspace partitioning

Header Data

From: “Vladimir Z. Nuri” <vznuri@netcom.com>
To: Gary Howland <gary@systemics.com>
Message Hash: 1245a1dcfffddefe6664dd1792ea34371ba2bca11daa83454dda8c7c3e512dda
Message ID: <199610042021.NAA29619@netcom7.netcom.com>
Reply To: <325501C5.167EB0E7@systemics.com>
UTC Datetime: 1996-10-04 23:11:25 UTC
Raw Date: Sat, 5 Oct 1996 07:11:25 +0800

Raw message

From: "Vladimir Z. Nuri" <vznuri@netcom.com>
Date: Sat, 5 Oct 1996 07:11:25 +0800
To: Gary Howland <gary@systemics.com>
Subject: Re: DESCrack keyspace partitioning
In-Reply-To: <325501C5.167EB0E7@systemics.com>
Message-ID: <199610042021.NAA29619@netcom7.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


of course, any number in the range of a random number
generator is theoretically as likely/unlikely to appear.

however, consider the case in which DES keys are generated
from ascii sequences or words that people enter in at
password prompts, which is in fact how the unix passwd file
word. these obviously have far less randomness
and Gary's attempt to narrow the keyspace is highly 
relevant.

also, I took his post as suggesting that some parts of the
keyspace ought to be searched at higher priority than
others. in the above example, keys that correspond to 
ascii sequences typable on a keyboard should be searched
first in the keyspace.

a lot of systems use DES only in conjuction with a one-time-key
generated for a particular message. (similar to the way
PGP uses IDEA for the session key, and transmits this encoded
key using RSA). in general I would say these could be considered
random in a way that the previous "less-than-random" property
doesn't hold.

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