phc-discussions - Re: [PHC] "Attack on the iterative compression function"

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Date: Fri, 17 Apr 2015 10:05:47 -0700
From: Bill Cox <waywardgeek@...il.com>
To: "discussions@...sword-hashing.net" <discussions@...sword-hashing.net>
Subject: Re: [PHC] "Attack on the iterative compression function"

On Tue, Apr 14, 2015 at 3:29 PM, Solar Designer <solar@...nwall.com> wrote:

> This is another great contribution by the Argon team, which I think
> hasn't received its due attention in here yet.
>
> Please see the Argon2 paper, page 13 (in current revision).
>

The Argon team does great work, but they continually warp there conclusions
to favor their incorrect world-view that the original Argon algorithm is
better than all the rest.  They use outlandish definitions for common
things like "time*memory" defense, and wafer-sized ASICs holding zero
latency multi-gigabyte nearly-zero power cache RAM.

Other than that, this paper is a great analysis...

Here's the outrageous claim they make against Yescrypt:

  for 1/4 memory, Yescrypt has a 1/2 "Time-memory product"

In their previous table, they say that at a 1/4 memory attack, the attacker
must do 1135 times more computation.  The time*memory defense as used by
the whole world other than the Argon team is therefore 283.75.  This paper
is off by a factor of 567.5!

I do not consider this a weakness of Yescrypt.  I wish the Argon team would
start using proper terminology.

Bill

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