phc-discussions - Argon2 modulo division

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20150421032631.GA18820@openwall.com>
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