phc-discussions - Argon2 modulo division

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Date: Tue, 21 Apr 2015 06:26:31 +0300
From: Solar Designer <solar@...nwall.com>
To: discussions@...sword-hashing.net
Subject: Argon2 modulo division

Dmitry, all -

It appears that Argon2 uses modulo division with arbitrary (and
changing) divisors (usually not powers of 2).  Argon2d applies this to
secret-dependent integers.  This is an extra source of timing leaks, on
top of secret-dependent lookup addresses.

Do we consider this a drawback?

TwoCats had this too, but I avoided this maybe-drawback in yescrypt.

Alexander