A method for creating a multiplexed data stream composed of encrypted multimedia data (310), decryption information, and stream key data. The process of creating the multiplexed data stream (320) usesa multiplexing pattern that is determined in view of a stream key data and an instrument identification number preferably corresponding to the receiver of such multiplexed data stream. Stream key datathat is transmitted as part of the multiplexed data stream is placed in predetermined locations, for the benefit of a decoder that extracts such stream key data from the predetermined locations. Them ultiplexed data stream is then processed for transport (330). A method and apparatus for demultiplexing the multiplexed data stream is also disclosed.