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Message-ID: <4F8893BE.1020002@banquise.net>
Date: Fri, 13 Apr 2012 22:59:42 +0200
From: Simon Marechal <simon@...quise.net>
To: john-users@...ts.openwall.com
Subject: Re: .chr files (Was: automation equipped working place
of hash cracker, proposal)
Le 13/04/2012 22:46, Aleksey Cherepanov a écrit :
> Assume that we have mixed passwords of two patterns. We build .chr and
> enumerate each password with a number according to its positions in a list of
> candidates this .chr file provides. We drop one password from our set and redo
> the steps and numbers are changed: if ratio between the biggest group of
> password and the smallest group is higher than before then it was a password
> from the smallest group else it was a password from the biggest group. I am
> not sure how to measure numbers right.
You assume that incremental mode will be a good tool to model password
patterns. I do not believe this is the case for most, even if it worked
reasonably well during the constest.
> Though I think there could other statistical methods to find groups of
> passwords. Something like cluster analysis is going onto mind.
I a tried to find ideas on the topic of identifying mangling rules
patterns. When one of them exists (and is plain enough, a simple
mutation rule combined with some append/prepend), it is easy to
recognize it. When it gets more complex, you need more rules, and my
stuff obviously doesn't run in polynomial time (but linear space I believe).
Other methods I could think of would be even slower. Is there somebody
on this list who is knowledgeable about linguistics and/or statistics ?
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