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Date: Thu, 22 Jan 2009 10:42:40 +0100
From: Samuele Giovanni Tonon <samu@...uxasylum.net>
To: john-users@...ts.openwall.com
Subject: Re: keyspace, mask password and dumb bruteforce

On Wed, 2009-01-21 at 17:37 +0300, Solar Designer wrote:
> On Fri, Jan 16, 2009 at 03:49:28PM +0100, Samuele Giovanni Tonon wrote:
> > A "collision free" algorithm is to simply scan through the keyspace by
> > going incremental (i.e. 0000 0000, 0000 0001, 0000 0002 and so on...) 
> > and splitting our work in to "chunks" for each client. 
> > These chunks must be big enough to make the client work for some time
> > (some hours/some minutes) and then give back a feedback to the server.
> > 
> > Then there's Jtr and his incremental mode which, for what i've
> > understand, will go to search the same keyspace as above but going to
> > test some "most likely to be" passwords first; This way, unfortunately,
> > is not higly distributed tough
> 
> Actually, it is not very hard to split the workload across multiple
> nodes in a collision free way and without consuming much bandwidth while
> still using JtR's incremental mode.  Please see:
> 
> 	http://www.openwall.com/lists/john-users/2005/11/21/2
> 
> (especially the last paragraph).
> 
solar you are a living search engine, i looked in to the list archives
for almost three days and never read that mesg :-)

> > even the wiki has a list of jtr distributed attempt;
> 
> This doesn't mean much.  People were implementing whatever they could
> think of and whatever they wanted to.

that conclusion came since there were many attempt to make a distributed
password cracker from john and none of them ever reached version 2.0 or
something stable which doesn't core dump in the next 3 hours, but i
guess my conclusions were wrong.
Also i don't wanna sound lame, i truly respect all the effort that has
been made in those distributed version of john, in fact they helped me a
lot by looking to their source code. 


> > As a quick solution to this problem i thought that maybe a solution is
> > to use "mask passwords list", which is not an innovative idea but could
> > work; with a mask password the user has the ability to restrict the
> > keyspace and it is still easy to split up chunks across the clients.
> > Basically it's making a bruteforce less dumb by using human brain other
> > than using heuristics and each client can easily self-produce the
> > keyspace to crunch, therefore saving network bandwith. 
> 
> If I understood you correctly, you're essentially suggesting to split
> the keyspace manually.  Yes, this is what I recommend most of the time -
> especially when the number of CPU cores to distribute the workload
> across is relatively small.  You might want to take a look at these
> older postings:
> 
> 	http://www.openwall.com/lists/john-users/2008/04/08/4
> 	http://www.openwall.com/lists/john-users/2005/08/24/4

yes, that idea came from reading exactly these two posts and extending
it to, why do i have to manually launch (or set up a script to do that) 
a cracker on each core or each pc when i could do a program to do that ?
however at the moment you made me look to new ways that i never thought
of due to lack of knowledge in this field, so i'm going back to the
bench and do some homework before saying stupid things :-)

Cheers
Samuele


-- 
While various networks have become deeply rooted, and thoughts have been
sent out as light and electrons in a singular direction, this era has
yet to digitize/computerize to the degree necessary for individuals to
become a singular complex entity.
  KOUKAKU KIDOUTAI Stand Alone Complex


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