Patent ID: 7403618
Filing Date: 2008-07-22
Classification: H04N

Abstract:
1. A transmission system for providing conditional access to transmitted data; the system including a transmitter and a plurality of receivers coupled via a network; the transmitter including means for transmitting: each of the receivers being associated with a corresponding set of a plurality of device keys, wherein at least two of the receivers are associated with sets that comprise at least one corresponding device key, each of the receivers including: wherein the transmitter is operative to renew a set of device keys of a specific receiver by transmitting to the receiver a new set of device keys encrypted under control of a fixed device key that is unique for the receiver, and wherein the receiver is operative to receive a set of encrypted device keys, and the receiver includes a third decryptor for decrypting the set of encrypted device keys under control of a fixed device key that is unique for the receiver.