theoretical results in watermarking

[R. A. Hettinga]

--- begin forwarded text


Status:  U
Date: Tue, 19 Feb 2002 14:06:58 -0500
From: Richard Lethin <lethin at reservoir.com>
Organization: Reservoir Labs, Inc.
To: dcsb at reservoir.com
Subject: theoretical results in watermarking
Sender: bounce-dcsb at reservoir.com
Reply-To: Richard Lethin <lethin at reservoir.com>

YALE UNIVERSITY
DEPARTMENT OF ELECTRICAL ENGINEERING SEMINAR
Dr. Aaron S. Cohen
Research Laboratory for Electronics
Massachusetts Institute of Technology
will give a talk on
Communication with Side Information:
Watermarking and Writing on Dirty Paper
Wednesday, February 27
at
11:00 am
in
Room 500, Watson
Abstract
We consider two communication scenarios in which a transmitter must make
the input to a noisy
channel similar to some exogenous side information sequence. The first
such scenario is watermark-ing
for copyright protection. In watermarking, an original data sequence
(the side information) is
modified slightly in order to embed some extra information (e.g., the ID
number of the owner of
the data). The embedded information must be recoverable even if an
attacker has further modified
the data in order to make an illegal copy. Watermarking has become
increasingly important due to
the ease with which data can now be reproduced and transmitted around
the world. In this talk,
we answer some fundamental questions about watermarking system
performance. We first show
how much information a watermarking system can embed and how to design
good watermarking
systems. We also investigate whether it is better to have noisier data.
We finally compare the
optimal attack with lossy compression.
In the second scenario, the communication system has to be robust
against independent additive
noise instead of an attacker as in watermarking. Such a model is useful
when digitally enhancing
analog systems or when designing broadcast codes. Costa considered the
case where both the
side information and the additive noise are Gaussian, and dubbed it
“writing on dirty paper”.
Costa’s surprising result is that the maximum rate of information that
can be transmitted does not
depend on the variance of the side information. We extend Costa’s result
by considering general
distributions and showing that the maximum rate does not depend on the
statistics of the side
information if and only if (under certain conditions) the additive noise
is Gaussian. That is, the
side information need not be Gaussian but the additive noise must be
Gaussian in order for Costa’s
result to hold.
---------------------------------------------------------------------
The Cryptography Mailing List
Unsubscribe by sending "unsubscribe cryptography" to majordomo at wasabisystems.com