phc-discussions - Re: [PHC] Panel: Please require the finalists to help with benchmarks

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Message-ID: <CAOLP8p5pLJ+Gj7esdBTgi_ecVQM8qB8uzjs37Ns2vutTXT0Z4g@mail.gmail.com>
Date: Thu, 2 Apr 2015 18:17:00 -0700
From: Bill Cox <waywardgeek@...il.com>
To: "discussions@...sword-hashing.net" <discussions@...sword-hashing.net>
Subject: Re: [PHC] Panel: Please require the finalists to help with benchmarks

On Thu, Apr 2, 2015 at 1:56 PM, <Stefan.Lucks@...-weimar.de> wrote:

> On Thu, 2 Apr 2015, Dmitry Khovratovich wrote:
>
>  Thus I would insist on hardcoding the number of rounds, hash function
>> type, flags, etc. into the PHS() call. The designers should make a choice.
>>
>
> I kind of agree, there can be too much choice. On the other hand, no
> designer is able to guess how much memory the user (or, more likely, the
> sysadmin) is willing to donate for password hashing, and how much time the
> user (or the sysadmin) is willing to spend for password hashing ... and
> even when the time is fixed, some tool is needed to conveniently fix the
> time parameter. This is what Catena-Axungia is for
>
>   https://github.com/medsec/catena-axungia

I like this approach, though I think for benchmarking we can just have the
authors choose the parameters.  I agree with Dmitry that parameters should
typically not be chosen by the end-user, though I think the number of
rounds, number of lanes, and other tunable parameters could be selected
based on the number of threads the user allows, and the total memory to be
hashed.  For benchmarking, authors should pick a minimum t_cost they feel
is secure, and a number of rounds that give the best memory*time defense
with good compute time hardness.  I still have not heard any reasons we
need more than the current reduced Blake2b round or more than 2 of
Alexander's new hash for any security reasons other than to make memory
indistinguishable from random, and I don't see that as a particularly
important goal.

>
> ... and yes, this is for Catena, but of course, something similar could
> (or, as I would claim, should!) be build for the other candidates as well.
>
> Agreed!  At least for the winner :-)  We should make that a condition of
acceptance of being the winner, IMO.

Bill

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