phc-discussions - Re: [PHC] Memory performance and ASIC attacks

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Message-ID: <53FF5B21.1090801@ciphershed.org>
Date: Thu, 28 Aug 2014 12:38:57 -0400
From: Bill Cox <waywardgeek@...hershed.org>
To: discussions@...sword-hashing.net
Subject: Re: [PHC] Memory performance and ASIC attacks

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On 08/28/2014 12:28 PM, Marcos Simplicio wrote:
> Hi,
> 
> On the matter of parallelizability: our code does not allow 
> multithreading basically because we did not have time to implement
> and test the "p" parameter discussed in the "extensions" part of
> the documentation. :(
> 
> This is about to change, though, since we have been focusing on
> the "extensions" discussed in the algorithm's proposal (mainly on
> how to control the memory bandwidth up/down while adding
> parallelism). AFAIU, the approach adopted in different from those
> of Yescript and Twocats, as the parallelism is on the memory matrix
> level rather than on the level of cells. There may be some
> (dis)advantages when compared to those two, but we will only be
> able to tell after we finish our tests :)
> 
> BR,
> 
> Marcos.

Sweet!  Actually, both TwoCats and Yescrypt multi-threading have some
defense against running threads sequentially rather than in parallel,
in that there is some hashing between the memory used by different
threads.  Both make use of SIMD level parallelism and thread level.
Lyra2 is very efficient for a PHC entry, and your team is doing great
work so far.  I'm confident you will get this part right :-)

Bill
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