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Date: Fri, 25 May 2012 01:59:43 +0200
From: magnum <john.magnum@...hmail.com>
To: john-dev@...ts.openwall.com
Subject: OpenCL crypt-sha512 (was: john-users: Can Excessive Rounds make Password
 cracking Infeasable)

On 05/25/2012 12:25 AM, magnum wrote:
> On 05/24/2012 11:03 PM, Solar Designer wrote:
>> On Thu, May 24, 2012 at 10:49:41PM +0200, magnum wrote:
>>> FWIW, some very quick tests on Solar's test gear with the hash above:
>>>
>>> CPU (8 cores): 4.75 c/s
>>> GTX580: 4300 c/s
>>> HD7970: 6000 c/s
>>>
>> These GPU speeds are not realistic.  There must be a bug or just lack of
>> support for non-default numbers of iterations for this hash type (this
>> is something for us to correct if so!)

Claudio,

Your format has some problems with cracking real hashes, even though it
passes self-tests.

Here's a way to make any number of test hashes:

$ for i in `../run/john -inc -stdout | head -10000 | shuf | head -20`;
do echo $i | mkpasswd -m sha-512 -P 0 ; done > testhashes

All should be cracked quickly using incremental mode. You can also add
-R <rounds> to mkpasswd, but the problem is not really with rounds but
with salts (it seems). You can set a fixed salt with -S, I tried
attacking only one or a few salts and 100% was cracked.

magnum

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