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Message-ID: <20150819183534.GA18563@openwall.com>
Date: Wed, 19 Aug 2015 21:35:34 +0300
From: Solar Designer <solar@...nwall.com>
To: discussions@...sword-hashing.net
Subject: Re: [PHC] Argon2 CPU/GPU benchmarks
On Wed, Aug 19, 2015 at 07:27:30PM +0200, Dmitry Khovratovich wrote:
> > What do you mean by GPU portability here? Simplifying OpenCL
> > implementations for testing, or for actual defensive use of GPUs?
>
> Simplifying implementations for testing, in order to realize all the
> possible advantages of GPU cracking earlier than the attacker does so.
Makes sense. We don't have such suggestions currently (that wouldn't
have significant drawbacks).
> What is the parallelism parameter BTW? p=1 for all schemes?
Yes. Agnieszka also ran some tests with 5, but I am not considering
those yet.
> > Combined, these result in Titan X being 3072/640*1000/1096 = 4.38 times
> > faster. In case memory bandwidth ever becomes the limiting factor (as
> > we optimize the code more), it's similar too: 336/80 = 4.2 times faster.
>
> I understand, but why do you get 37x advantage of yescrypt from there?
> Don't these properties speed up yescrypt as well?
Oh. You're absolutely right. It's totally flawed logic on my part.
Please disregard those 37x and 27x figures.
The expectation is that original Argon2 will run on Titan X maybe 2 or 3
times faster than on i7-4770K at these settings:
1861/2480*3072/640*1000/1096 = 3.29
4227/7808*3072/640*1000/1096 = 2.37
whereas yescrypt will run maybe 2 or 3 times slower on Titan X than on
the CPU:
419/4736*3072/640*1000/1096 = 0.39
That's obviously the same difference we see between Argon2 and yescrypt
on 960M vs. the CPU.
Alexander
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