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Date: Wed, 31 May 2006 22:53:07 +0200
From: "Otheus (aka Timothy J. Shelling)" <otheus@...il.com>
To: john-users@...ts.openwall.com
Subject: Re: Parallalizing John the Ripper

It occured to me, just before I looked at the "Pippin" MPI project, that in
both Ryan's implementation and in mine, once a particular hash is cracked by
a particular task, the other tasks are *still* comparing against the cracked
passwords. They are also generating hashes from salts that may be no longer
needed.

It looks like Pippin aimed to solve this, but they used a jackhammer to
remove this splinter. They re-wrote several *files* in C++.  But from their
power-point presentation (which has several errors, by the way), they solve
this by distributing the passwords so that salts are clumped together on one
task.  That wouldn't scale well in a number of scenarios, and from what you
(Solar) has mentioned in the past, distributing the salts would undermine
many oh John's optimizations.

So perhaps Solar or someone can point me the way.  After a task cracks a
password, it should broadcast the cracked hash (or perhaps index) to all
other tasks.
Question: Where/how should the other tasks handle this event?  I'm somewhat
lost on this, but my current guess is that for each cracked ciphertext
received via MPI, the task must find the right salt list and pw entry can
call crk_process_guess(). If there's a cleaner way, I'd love to know.


Question: Where/how should the cracking task broadcast this event? It seems
pretty clear that this should be in crk_process_guess(). Of course, if my
guess above is true, the crk_process_guess must be called for every cracked
password received from the other tasks, then this would be split into two
functions right after the log() call. Alternatively, I could add a boolean
parameter to the function which would be use to skip re-broadcasting and
re-logging the cracked password.

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