An encryption arrangement for multiple encryption of television programs.
A system according to embodiments 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. 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 same bandwidth while permitting
coexistence of multiple conditional access systems in a single cable
television system.