Patent ID: 7506376

Claim:
A copy protection method for digital media, the method comprising the steps of: (a) encrypting an original media data set with a media key having a symmetric algorithm and encrypting said media key with a public key of a compliant device; (b) delivering said encrypted media data set and said encrypted media key to a compliant playing device, wherein said original media data set includes an owner watermark containing an owner identification and owner copy-control information for the media data set; (c) decrypting said delivered media key with a private key of said playing device; (d) decrypting said delivered media data set with said decrypted media key; (e) adding a player watermark to said decrypted media data set if said decrypted data set is not marked with at least “free copy”, said player watermark containing a player identification of said playing device and player copy-control information, wherein said player copy-control information is derived from said owner copy-control information; and (f) if passing said watermark-added media set to a recording device. encrypting said watermark-added media data set with said decrypted media key, encrypting said decrypted media key with said public key of said compliant device, and passing said encrypted watermark added media data set and said encrypted media key to said recording device without a compliance test, and (e) if passing said-watermark-added media data to a displaying device, performing a compliance test with said displaying device and if said compliance test is successful, passing said watermark-added media data set and said decrypted media key to said displaying device without encrypting.