TIME DIVISION PARTIAL ENCRYPTION

摘要

An encryption arrangement for multiple encryption of television programs. A system according to embodiments of the present invention multiple encrypts only a proition fo 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 iwthin a single system. In one embodiment, a time slicing technique is used to encrypt portions of a program on a time allocated basis. By onlty encrypting a porition of the program, dramatically less bandwidth is consumed than the laternative of multiple encryption of all program data, thus permitting a larger number of progreams to be carried over the same bandwidth while permitting coexistence of multiple conditional access systems in a single cable television system.