From: Matt Blaze <mab@research.att.com>
Date: Tue, 19 Dec 95 12:02:14 PST
To: cypherpunks@toad.com
Subject: revised time quantization package (Unix & WIN32) available
Message-ID: <199512192009.PAA17051@nsa.tempo.att.com>
MIME-Version: 1.0
Content-Type: text/plain


A revised version of my simple CPU time quantization package is
now available for most Unix and, thanks to the efforts of Frank
O'Dwyer (Rainbow Diamond Ltd), WIN32 platforms.  The package provides
a simple interface to encapsulate code blocks that must run in a
multiple of a coarse-grained "quantized" amount of CPU time.  It
is useful in building various on-line cryptographic protocols in
which an attacker could otherwise learn key information by observing
the time the target takes to perform calculations that use the
secret (c.f., Paul Kocher's recent attacks).

The basic idea is that you can specify a "quantum" such that at
the end of an encapsulated block the CPU will busy-wait until the
next quantum multiple.  Fine-grained (below the quantum) timing
information is thereby denied to the observer (including unprivileged
processes on the same machine).  The code is quick-and-dirty and
only runs on Unix-centric and WIN32-based platforms.  Test and use
at your own risk.

There are (basically) no restrictions on the use or distribution
of the (very simple) code.

Get it from:
	ftp://research.att.com/dist/mab/quantize.shar

The quantize package is also part of Jack Lacy's cryptolib package
(watch this space for details).

-matt