phc-discussions - integer multiply was not always constant-time

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Date: Wed, 5 Mar 2014 02:41:49 +0400
From: Solar Designer <solar@...nwall.com>
To: discussions@...sword-hashing.net
Subject: integer multiply was not always constant-time

BTW, let's not forget that even MUL/IMUL were not constant time on 486
and prior (and it's similar on similarly old non-x86 archs).  So if we
care about being timing-safe even on CPUs this old, we should probably
avoid multiplication in the portion where we avoid cache timing leaks.

Alexander