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Date: Sun, 21 Aug 2011 02:05:57 -0500
From: Richard Miles <>
Subject: Re: John with Radeon graphical card supports?

Hi Solar

> This is unrealistic.  First, John the Ripper with -jumbo supports so
> many hash and cipher types that reimplementing them e.g. in OpenCL
> would be a lot of work.  So there would need to be specific demand for
> each individual hash/cipher type in order for it to be reimplemented.
> Second, a few of them are not even implementable on GPUs efficiently.

I believe it's really a huge amount of work, I just talked about it
because appears that GPU is the new toy to speed up password cracking.
I was not aware that some implementations were not efficient in GPU.

>> If you allow me I want to do 2 suggestions for you consider on this development:
>> - If doesn't exist, add support for multiple cards on the same computer,
> This is definitely being considered.


>> for example, someone with 2 graphical cards could have an
>> enormous benefits instead of just one.
> Not enormous, but at most a 2x speedup, which would translate into maybe
> a few percent of extra passwords cracked.

I'm far away to be a specialist, but I see people saying that some GPU
cards may speed up 20 times password cracking in comparison with a
normal computer CPU. So, if we use 2 GPU cards it will be the double
(40 times), not?

There is a very great article I wrote sometime ago about this:

> I am not saying we shouldn't support multiple GPUs - we definitely
> should.  I am merely saying that you're over-estimating the effect.
> A mere 2x speedup (or even slightly less) does not give "enormous
> benefits" in terms of actual cracking results.

I agree with you, maybe I misunderstood the article...

>> - Consider add support for WPA/WPA2 handshake.
> Yes, this is also being considered.  Specifically, we will likely have
> PBKDF2 with SHA-1 implemented on GPUs, which will be used for MSCash2
> hashes as well as for WPA/WPA2.


> Thanks for voting for these features.
> Alexander

It's a pleasure.


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