phc-discussions - Re: [PHC] Re: Proposed changes to author's code

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Date: Tue, 8 Apr 2014 08:08:44 -0400
From: Bill Cox <waywardgeek@...il.com>
To: discussions@...sword-hashing.net
Subject: Re: [PHC] Re: Proposed changes to author's code

On Tue, Apr 8, 2014 at 7:07 AM, Dmitry Khovratovich
<khovratovich@...il.com> wrote:
> Hi Bill,
>
> thank you for the efforts!
>
> The legal input ranges for Argon are
> 1 <= t_cost <= 2^24
> 1 <= m_cost <=2^24
>
> We prefer t_cost = 3 for all m_cost starting from 128, and t_cost  = 256 -
> 2*m_cost for those smaller.
>
> The total memory size in bytes is m_cost*1024.
>
> I do not quite understand what you mean by average memory*time profile.
> Argon always does ((6t_cost + 5)*m_cost*64) memory accesses and performs
> f(t_cost,m_cost) operations, where f is a bilinear function (see Section 6.4
> of the specification for details).
>
> We do not recommend using the reference implementation for benchmarking
> though. An optimized implementation will appear soon.
>
> Best regards,
> Dmitry

Thanks!  I set the minimum t_cost to 3 for now, since I see in the PHS
function it will do this for me if I specify lower.  The test vectors
wrapper tries to increase m_cost for any given t_cost until the
runtime is > 0.1 seconds.  I was only going to use the longer runtime
values for benchmarking.

I agree that the reference implementations are not very useful for
benchmarking.  It's worse for those algorithms that are optimized for
SSE/AVX2 (like mine) or use AESENC (even worse!).  I'll go ahead and
build the auto-testing wrappers, but if authors prefer, I'll only post
numbers for optimized versions.  Alternatively, I have have separate
tables for optimized vs unoptimized.

Bill