DECODING AND DECRYPTION OF PARTIALLY ENCRYPTED INFORMATION

摘要

An encryption arrangement for multiple encryption of television programs (100). A system according to embodiments of the present invention multiple encrypts only a portion of data (118, 124) 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. By only encrypting a portion of the program (118, 124), 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 same bandwidth while permitting coexistence of multiple conditional access systems (36, 136) in a single cable television system.