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Date: Thu, 20 Sep 2007 20:21:41 +0200
From: Michal Luczaj <>
Subject: Re: Markov filter password generation

Simon Marechal wrote:
>> I just "released" an experimental support for Markov filter password
>> generation. (...)
>> I need some feedback on this generator effectiveness, especially with
>> non french passwords. If it turns out it works well, I will release a
>> clean patch for JtR.

Hello there,

Congratulations, Simon. I gave it a short test and I must say I was very
positively surprised.

I've ran your patched John twice (about 3,5h each run) against a list of
946 unique raw-MD5 hashes (of mixed Polish, English and few
Japanese/romaji passwords) with the fallowing results:

incremental=all, guesses: 365
incremental=alnum, guesses: 398
markov=266:0:0:8, guesses: 469

(At first I've ran only incremental=all, but realized that would be
unfair in comparison with this Markov level.)

It looks like your Markov filter, just as you wrote before, "is more
effective /during a certain amount of time/". And, of course,
incremental mode found some passwords that Markov didn't.

Strengths and weaknesses of both modes are quite obvious, but it would
be really good to have such an addition to John, so I'll be waiting for
a clean patch. Great job!


P.S. Just for fun, with john.pot already filled after those
incremental/markov passes, I've run markov=250:0:0:16 - 17 new guesses,
~4h. And then markov=257:0:0:30 - 2 more (9 chars long) guesses, ~8h.
And that's really really nice. But I've noticed that 250:0:0:16 found
some additional short (6-7 chars long) passwords that 266:0:0:8 didn't.
Is it correct behavior?

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