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Date: Mon, 8 Apr 2013 01:18:49 +0200
From: Frank Dittrich <frank_dittrich@...mail.com>
To: john-users@...ts.openwall.com
Subject: Using incremental mode and markov mode with multiple cores (was:
What am I doing wrong?)
On 04/08/2013 12:37 AM, Sandra Schlichting wrote:
> My other desktop computer is a quad core, so if I want to only try 8
> characters passwords and dedicate 2 cores to Marcow and 2 for
> Incremental.
I wouldn't skip length < 8.
So, I would use 2 incremental mode sessions, one for up to 7 characters,
one for 8 characters:
./john --format=raw-md5 hashes --session=inc_1-7 --incremental
--max-length=7
./john --format=raw-md5 hashes --session=inc_8 --incremental=All8
(This assumes that hashes is the file containing the hashes you want to
crack.)
Once these sessions run, I would read doc/MARKOV for instructions how to
determine what level to use.
(Since you use 2 cores, calculate with twice the time you want to spend
cracking these hashes.)
Say you end up using level 220.
Then, you can start the 2 Markov sessions like this:
./john --format=raw-mdc hashes --session=markov1 --markov=220:0%:50%
./john --format=raw-mdc hashes --session=markov2 --markov=220:50%:100%
If you insist to skip length 1-7 and you want to avoid possible overlaps
for longer incremental mode and markov mode sessions, I would use:
./john --format=raw-md5 hashes --session=inc_8 --incremental=All8
For length 8, splitting incremental mode across 2 cores would only make
sense for salted hash formats, not for raw-md5. (For salted hash
formats, you would split the passwords grouped by salt into 2 different
files, and use these individual files. With saltless hashes, you would
just do the expensive part (computing the hashes) twice, and split the
inexpensive part (comparing hashes to be cracked with the hashes that
have been computed).
./john --format=raw-mdc hashes --session=markov1 --markov=220:0%:33%:9-15
./john --format=raw-mdc hashes --session=markov2 --markov=220:33%:66%:9-15
./john --format=raw-mdc hashes --session=markov3 --markov=220:66%:100%:9-15
The meaning of the parameters used in my Markov mode examples, and more,
should be explained in doc/MARKOV.
If any questions remain, please don't hesitate to ask, so that we can
improve doc/MARKOV.
Frank
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