ELEMENTARY STREAM PARTIAL ENCRYPTION

摘要

An encryption arrangement for multiple encryption of television programs. A system according toembodiments of the present invention multiple encrypts only a portion of the data required for full presentation of a television program to permit coexistence of multiple conditional access encryption systems associated with multiple manufacturer's set-top boxes within a single system. In one embodiment, only audio data are encrypted leaving video in the clear. By only encrypting a portion of the program, dramatically less bandwidth is consumed than the alternative of multiple encryption of all program data, thus permitting a larger number of programs to be carried over the samebandwidth while permitting coexistence of multiple conditional access systems in a single cable television system.