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Date: Mon, 13 May 2013 22:22:09 +0400
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: Incremental mode in 1.7.9.14

magnum -

On Mon, May 13, 2013 at 07:30:44PM +0200, magnum wrote:
> I had similar results with two-character candidates and so on. Is there any way short lengths could get more "weight", or some other mitigation for this "regression"?

They get so little weight because they're so rare in the training set
(perhaps non-existent, for these specific characters?)  However, you may
adjust their weight here in charset.c:

			est *= (*cracks)[length][pos][count];
			if (est < 1e-3) /* may adjust this */
				est = 1e-3;

Change the 1e-3 (in both places) to something larger (e.g., 1e-2).
I think the largest value that makes sense is 1.0.  So maybe test these:

0.01
0.1
0.5
0.9
1.0

... and you've already tested 0.001 and are unhappy with it.  In your
testing, also see how this affects efficiency (in terms of successful
guesses per candidates tested) for actual runs (e.g. train on one half
of RockYou, test on the other, or train on RockYou and test on another
real-world data set).  I suspect that as results "improve" in terms of
uncommon short strings being tried sooner, they will be getting worse in
terms of efficiency.  I understand that we do need to be testing really
short strings reasonably early anyway, though.

Let me know which value you think gives the "best" results.

Thanks,

Alexander

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