john-users - Re: Re-ordered 'Single Mode' Ruleset

Openwall GNU/*/Linux 3.0 - a small security-enhanced Linux distro for servers

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Date: Sat, 24 Apr 2010 01:30:54 +0400
From: Solar Designer <solar@...nwall.com>
To: john-users@...ts.openwall.com
Subject: Re: Re-ordered 'Single Mode' Ruleset

Matt,

Here's an additional comment:

It is not clear whether you have full (or any) separation between your
training and test sets when you re-order the rules.  (You do say that
you have such separation for your "UnLock" test, but that's another one.)

In other words, the improvement from "Original Single Rules" to "Edited
Single Version 2" that you've demonstrated might be partially
attributable to you training (re-ordering) the rules on the same set
that you later test them on.

FYI, the original rules were similarly trained (re-ordered) on Unix
crypt(3) hashes in 1990s, although they have since been revised in many
ways.  (The revision with JtR 1.7.4, while appearing like a major one,
was actually mostly limited to making use of the new preprocessor
capabilities, which allowed for a 30% reduction in the number of ruleset
lines while producing essentially the same candidate passwords.)

On Thu, Apr 22, 2010 at 11:32:24PM -0400, Matt Weir wrote:
> http://reusablesec.blogspot.com/2010/04/optimizing-john-rippers-single-mode-for.html

Thanks again,

Alexander