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Date: Thu, 07 Mar 2013 22:50:03 +0400
From: "Sergey V." <>
Subject: Re: [question] How to crack a specific ssh key pass

On 2013-03-07 at 10:44:36, Thomas F├ętiveau <> 
> Hi !

> I've just discovered john and I am trying to retreive a pass for one of
> my ssh private key.
> I've tried the incremental modes but there are limited to 1 to 8 length
> passwords.
> The password I'm searching for has between 10 and 16 chars and is
> composed only of these characters: [a-z][0-1-3-5-6] (actually, even
> less, I'm sure there is no 'w', 'x', 'y' nor 'z' letters).
Since you know possible characters I recommend to use an external mode. See 
"List.External:KnownForce" mode in john.conf (or john.ini) for example. Also 
see doc/EXTERNAL for more info.

But... If I understand your pattern correctly you mean that the password 
contain only characters a-v and digits 0,1,3,5,6. Then keyspace is 
sum(27^i, i, 10, 16) = 82834383187294870546773
and unfortunately it's VERY big for ssh format.

> I've read that searching in incremental modes for more than 8 characters
> doesn't make sense because it would take too long.
> But is it still true with the range of characters I have ? ie: about 28
> different chars
> If it would still make sense, what should I do to make john searching
> for this password ? (I'm running it under windows)
> On a side note: I'm running under a multi-core multi-threaded win 7 64
> bit and the john-opm.exe doesn't use more thread nor core nor CPU usage
> than john.exe (the both use just about 12,5% of my overall CPU capacity).
OMP works fine for me on linux. Which version of jtr you use? Are you see 
something like "... (8xOMP) ..." when run "./john --test --format=ssh"?

> Thanks in advance
> Tom

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