Abstract: 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. PID mapping techniques are used to distinguish between multiple encryptions. 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.

Abstract: A computing system includes data encryption in the data path between a data source and data storage devices. The data encryption may utilize a key which is derived at least in part from an identification code stored in a non-volatile memory. The key may also be derived at least in part from user input to the computer.