From: Adam Shostack <adam@lighthouse.homeport.org>
Date: Sun, 25 Feb 1996 05:23:05 +0800
To: nobody@REPLAY.COM (Anonymous)
Subject: Re: Digital Watermark
In-Reply-To: <199602240347.EAA05595@utopia.hacktic.nl>
Message-ID: <199602242040.PAA19841@homeport.org>
MIME-Version: 1.0
Content-Type: text


	Creating watermarks that can't be removed without degrading
image quality is not especially difficult.  The two tricky bits are
durability and collusion protection.

	Durability involves ensuring enough of a watermark remains
after the image is converted to a JPEG.  Colusion protection is making
sure that users can't compare images and remove the watermark without
a large number of users being involved.

Adam


| Financial Times, 22 Feb 96

| Attempts to remove the watermark would be virtually
| impossible without degrading the image quality. Moreover,
| counterfeiting would be almost impossible, says NEC. the
| Japanese electronics company.

-- 
"It is seldom that liberty of any kind is lost all at once."
					               -Hume