Patent ID: 7912219

Claim:
A method of generating an encrypted transport stream, comprising: encoding at least one program into a compressed video stream; coding random access points (RAPs) into the compressed video stream at which a decoder can begin decoding each said program; detecting the occurrence of RAPs in the video stream; generating encryption keys; upon detecting the occurrence of a RAP in the video stream, triggering an ECM generator to generate an entitlement control message (ECM) based on the current encryption key, said ECM including a message that allows the decoder to derive the current encryption key needed to decrypt the associated video stream; delaying the video stream to insert the ECM into the video stream just ahead of the detected RAP, said pairing of the ECM with the RAP allows the decoder to derive from the ECM the current encryption key needed to decrypt the associated video stream just in time to begin decoding the compressed video stream at the RAP; and encrypting the video stream with a crypto codeword appropriate to the associated ECM to provide an encrypted transport stream.