| 摘要 |
A system for providing or playing back a copy of scrambled content with a unique watermark comprises a storage device containing a scrambled copy watermarked with first pre-determined bits, a scrambled copy watermarked with second pre-determined bits and a processing unit programmed to provide at a request received from a user a copy of the complete scrambled content by combining parts of the scrambled copy watermarked with first predetermined bits and parts the scrambled copy watermarked with second predetermined bits in a manner unique to the user. In a system for providing scrambled content in particular by broadcasting, the scrambler for scrambling a clear content to provide scrambled content uses a first key(KF) to scramble the clear content. A processing device is programmed to provide clear content comprising a plurality of double parts, one part watermarked with first predetermined bits and one part watermarked with second predetermined bits, wherein the scrambler scrambles the parts watermarked with first predetermined bits with a second key(KZ) and the parts watermarked with second predetermined bits with a third key(KO). A key management program enforces receivers adapted to descramble the scrambled content with a combination of descrambled parts watermarked with first predetermined bits and parts watermarked with second predetermined bits unique to the respective receivers. <IMAGE> |
