Date: Fri, 9 Mar 2012 00:23:17 +0200 From: Milen Rangelov <gat3way@...il.com> To: john-dev@...ts.openwall.com Subject: Re: Re: [JtR PATCH] Support rar's -p mode by spawning external unrar process. Not a good idea to decrypt on GPU with -hp, not at least on AMD hardware with OpenCL (yes, I tried it ). This increases the GPR pressure and that impacts the whole kernel performance, it's not worth it. What I did not try is separate AES kernel post the setcryptkeys one, but I suspect kernel launch latency and memory transfers would make the whole excercise worthless. I also had a look at crark's CUDA code and I don't think it's quite optimal. Not quite glad with the speeds on my AMD hardware too. Porting that to OpenCL would be a disaster, at least on AMD hardware, it's like a quick port from CPU to GPU :) Too much loops, too much branches, byte addressable stores, the SHA1 implementation is like taken from OpenSSL too :) Anyway I am working on 7z now, things are even more fun here. On Thu, Mar 8, 2012 at 10:31 PM, magnum <john.magnum@...hmail.com> wrote: > On 02/29/2012 03:28 PM, Samuele Giovanni Tonon wrote: > > btw > > for those interested there's the cuda source available > > for crark . > > > > http://www.crark.net/Cuda-OpenSrc.rar > > I wonder if that code is what is used today (timestamps say 2009). The > code seems to be almost pristine OpenSSL C code. Nothing special except > he skips update() and inlines that functionality in the loop. Looks like > a good idea. Our current sha1 kernel could easily be modified to keep a > context. > > He decrypts in GPU too. For -hp mode that might be a good idea but for > -p mode I suspect AES-NI is they key to success if your CPU supports it. > > I have tried crark but not igrargpu, are they about the same in speed on > a specific card? > > magnum > > Content of type "text/html" skipped
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