Abstract:
In order to scramble as effectively as possible pay-television transmissions, the transmitter is made to transmit, at one and the same time, access messages and entitlement messages, all of them crypted and corresponding to a control word periodically loaded into a pseudo-random generator. In each receiver, the decoder comprises a control unit processing the various messages and sending them to a security processor which supplies a control word to the pseudo-random generator controlling the unscrambling.