Re: AES MAC security question

From: Rein Anders Apeland (apeland_at_mivu.no)
Date: 07/03/05


Date: Sun, 03 Jul 2005 10:24:21 +0200


On Sat, 2005-07-02 at 23:55 +0000, Colin Andrew Percival wrote:
> Kristian Gj?steen <kristiag+news@item.ntnu.no> wrote:
> > If the adversary has say 3600 attempts per hour, an adversary that
> > keeps at it for a year has probability roughly 0.007 of winning.
> > I could live with that.
>
> As long as each attempt only applies to a single car, yes. If someone
> can drive into a large parking lot and start broadcasting "unlock
> yourself and flash your lights" (encrypted with a series of keys) to a
> large number of cars, it might become more problematic.
>
> Colin Percival

The attacker then needs to get at least one transmitter ID and
the associated transmitter's key right at the same time. I believe
that would reduce the problem, right?

However, with each ID-hit, you run the risk of making some car
reject that fob. That could be a problem.

-- 
Mvh / Regards
Rein Anders Apeland
MIVU Solutions