A method and apparatus for distributing proprietary material employs multiple
watermarks
embedded in the proprietary material for enhanced copy protection. A first watermark
is to be processed by programmable and non-programmable devices configured to process
the first watermark for copy protection of the proprietary material. If a programmable
device eliminates the first watermark so that unauthorized copies of the proprietary
material can be made, then non-programmable devices configured to process a second
watermark as well as the first watermark look for and process the second watermark
for copy protection of the proprietary material upon their failure to detect the
first watermark.