[45186] in Cypherpunks
Re: Timing Cryptanalysis Attack
daemon@ATHENA.MIT.EDU (Perry E. Metzger)
Mon Dec 11 16:36:43 1995
To: Matt Blaze <mab@crypto.com>
Cc: cypherpunks@toad.com
In-Reply-To: Your message of "Mon, 11 Dec 1995 14:06:55 EST."
<199512111906.OAA01139@crypto.com>
Reply-To: perry@piermont.com
Date: Mon, 11 Dec 1995 14:44:14 -0500
From: "Perry E. Metzger" <perry@piermont.com>
Matt Blaze writes:
> >The trivial way to handle this is simply to check user time with the
> >right system calls and make sure it always comes out the same with an
> >apropriate number of sleeps.
>
> Of course, this works against a remote adversary, but not against one
> on the same machine who can look at actual CPU consumption (which doesn't
> increase when the target is blocked).
True enough, but using busy loops could handle that. However, I must
admit to being far more interested in handling the remote case
efficiently, especially given concerns people have about using
Photuris like systems on heavily pounded servers.
Perry
