Date: Fri, 1 Aug 2014 22:36:04 -0500 From: Dylan Staley <staley.dylan@...il.com> To: john-users@...ts.openwall.com Subject: PKZIP and GPU acceleration Hello, I've been playing around with John, compiled from the bleeding-edge branch (without modifying the Makefile), and I've noticed that a lot of the formats that have CUDA or OpenCL support are listed as such under the format option. Now, I've read countless articles about using John on CUDA-enabled EC2 instances, but seeing as how PKZIP *doesn't* have a CUDA or OpenCL version listed in the format option, does it even matter? I wanted to try and figure this out myself, so I ran john --format=PKZIP --test on two EC2 instances: * g2.2xlarge: 26 ECUs, 8 vCPUs, 2.6 GHz, Intel Xeon E5-2670, 15 GiB memory, NVIDIA GRID K520 GPU * c3.8xlarge: 108 ECUs, 32 vCPUs, 2.8 GHz, Intel Xeon E5-2680v2, 60 GiB memory The results were as follows: g2.2xlarge $ ./john --format=PKZIP --test Will run 8 OpenMP threads Benchmarking: PKZIP [32/64]... (8xOMP) DONE Many salts: 50288K c/s real, 6301K c/s virtual Only one salt: 22616K c/s real, 2837K c/s virtual c3.8xlarge $ ./john --format=PKZIP --test Will run 32 OpenMP threads Benchmarking: PKZIP [32/64]... (32xOMP) DONE Many salts: 144437K c/s real, 4519K c/s virtual Only one salt: 33959K c/s real, 1061K c/s virtual At this point, I was completely convinced that john is using the CPU for PKZIP, but I wanted to see just how much its performance could be increased in the real world. I used zip2john to get the hash for a zip file with a fairly simple password ("mi12345"). It took the g2 instance (the one with the GPU) 21 minutes to find the password, and the more powerful c3 instance 15 minutes to find the password. If I'm correct in assuming that John doesn't support using a GPU on PKZIP, what would be needed to enable this? Does anyone know of anything that is able to use the GPU with better performance than a CPU? Best, Dylan Staley
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