METHOD AND APPARATUS FOR ENCRYPTED DATA STREAM TRANSMISSION

摘要

A method of transmission and reception of scrambled data in which the scrambled data is transmitted to a decoder (2020), the scrambled data being passed to and descrambled by a security module or smart card (3020) inserted in the decoder (2020) and characterised in that the scrambled data stream is passed from the smart card (2020) back to the decoder (3020) in an encrypted form. The encryption of the data stream may be carried out on the card (2020) or as a secondary encryption step at transmission. The data stream may correspond directly to audiovisual data descrambled in the security module or to a stream of control word data subsequently used by the decoder to descramble a transmission.