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Date: Tue, 3 Dec 2013 05:25:44 +0400
From: Solar Designer <>
Subject: [openwall-announce] Energy-efficient bcrypt cracking (Passwords^13 slides)


Continuing (beyond) her GSoC project with Openwall, Katja Malvoni has
presented a comparison of bcrypt cracking efficiency achieved on chips
based on Epiphany many-core architecture and on an FPGA vs. common CPUs,
GPUs, and Intel MIC (Xeon Phi).  Katja has delivered the talk (including
a live demo) at PasswordsCon Bergen, and we've placed the slides online:

To summarize, bcrypt cracking is still very slow, but Epiphany and FPGAs
achieve much higher speeds per Watt, which enables higher density (more
chips per board, more boards per system).  While Katja's implementation
of bcrypt cracking on Epiphany is nearly optimal, there's still a lot of
room for optimization for FPGAs, so we expect to continue this project.

While this is primarily Katja's project and talk, I ended up joining as
a co-author for the presentation, to provide baseline performance and
power usage figures for CPUs, GPUs, and MIC.  While working on this, I
optimized JtR's bcrypt code for x86-64 some further, implementing 3x
interleaving, which helped some CPUs achieve higher speeds.  I also
produced and tried out revisions of Steve Thomas' bcrypt/AVX2 code on
Haswell and, with further changes to move to MIC intrinsics, on Knights
Corner (results: no luck getting any speedup over optimized scalar
implementations).  The 3x interleaving will likely get into an upcoming
JtR release, although it might not be enabled by default (unfortunately,
there are also CPUs where this change hurts performance a little bit).


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