Date: Mon, 24 Mar 2014 00:19:41 +0100
From: Jean-Philippe Aumasson <jeanphilippe.aumasson@...il.com>
To: discussions@...sword-hashing.net
Subject: Re: [PHC] Can I have two entries?

Regarding SAMS (Single-Author Multiple-Submissions), I agree with
Thomas' analysis.

We will accept all submissions that match the requirements, so in
theory one could submit 42 different functions. We'll just hate you
for that ;-)

On tweaks: submitters will be allowed to discuss/propose/announce
tweaks whenever they want, however it is planned that tweaks will only
be frozen and officially part of the submission after the finalists'
selection (as noted on https://password-hashing.net/timeline.html).

Fixes to bugs/typos/inconsistencies will of course be accepted
anytime. But I don't expect those to be major reworks of the
submission. In this kind of competition, too many design iterations
tends to be counterproductive.

On Sun, Mar 23, 2014 at 6:26 PM, Solar Designer <solar@...nwall.com> wrote:
> On Sun, Mar 23, 2014 at 05:53:19PM +0100, Kriszti?n Pint?r wrote:
>>
>> Solar Designer (at Sunday, March 23, 2014, 5:35:55 PM):
>> > For non-trivial algorithms, good pseudo-code is not any easier to produce
>> > than a machine-readable implementation.
>>
>> how about trivial algorithms? btw any algorithm is easier to write in
>> pseudocode, especially compared to low level languages like c. i don't
>> think there is a real debate about writing pseudocode is significantly
>> less error prone than writing actual code. it is pretty much the
>> rationale behind using them.
>
> To me, pseudo-code is something half way between "human friendly yet
> imprecise" and "machine-readable and more precise".  I'm not sure
> regarding these being more or less error prone.  I guess it depends.
>
>> they are also easier to read.
>
> Sometimes.  And yes, I said "human friendly" above, which is about this
> "easier to read" aspect.  However, this is not always true.
>
> For example, I find scrypt's crypto_scrypt-ref.c more specific and in
> some ways easier to read than the scrypt paper, which contains pieces of
> pseudo-code.  Yet the paper is valuable to have in addition to the code,
> because it clarifies other things that are not included or not explained
> in the one implementation (even the reference implementation).  We need
> both.  As to which to require for initial PHC submissions, if I were the
> only one to decide, I'd require only the code, accepting specification
> documents by a later date (although of course it'd be great if they're
> submitted along with the code).
>
>> > It's sort of OK if initial PHC submissions have bugs;
>>
>> so what good a buggy reference implementation is? what is the added
>> value?
>
> I feel I'd be repeating.  It confirms that the algorithm exists and is
> implementable, it allows to test its properties (to the extent the
> hopefully minor bugs don't interfere with that), it allows us to better
> evaluate complexity and efficiency of possible implementations.
>
> Efficiency is crucial.  We can't compare PHC submissions against each
> other without considering their efficiency.
>
> For example, escrypt tries to ensure it's no weaker than bcrypt in terms
> of attacks with GPUs, even at low memory settings.  The only way for me
> to be reasonably confident of this claim I'm making is to actually run
> an optimized implementation of escrypt on current machines and measure
> the achieved frequency of random memory accesses and parallel groups of
> accesses (two separate metrics) vs. those of bcrypt, and normalize for
> the difference in S-box sizes where appropriate.  And guess what, this
> goal was not fully achieved initially.  I had to go back and revise the
> way escrypt is defined, a few times, until I finally achieved this goal
> only a couple of days ago.  I produced several revisions of the
> implementation in the process, but this wasn't even a substantial
> portion of the effort involved.  Without the implementations, I would
> end up making a false claim, or I'd need to give up on this desirable
> property (not claim it and probably not achieve it).
>
> Maybe for your PHC submission it's different.  Maybe it has different
> goals and claims, where efficiency is somehow not as crucial (e.g., it
> might be sufficiently unique in other aspects that it's not directly
> competing with any other schemes in terms of attack/defense speed ratio).
>
> Can we end this discussion, please?  You've stated your opinion.  I've
> stated mine.  Let's move on.  We got real work to do.  Thanks!
>
> Alexander

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