METHOD AND DEVICE FOR SCRAMBLE CONTROL

摘要

PURPOSE:To improve the convenience of use by providing a means deleting forcibly key information in a receiver with a control signal from a transmission station to the device so that descrambling of the receiver once enabling descrambling of a transmission signal is disabled. CONSTITUTION:When it is required to cancel the permission by a transmitter to a receiver which receives descramble enable information 10 including a destination code 9, key information 6, a key identifier 7, and a key valid period 8, a key control information generating means 14 receiving a device identifier 1 and a key identifier 7 generates key control information 16 including the destination code 9 being the device identifier 1 and information 15 representing invalid key information indicated by the key identifier 7 and sends the information 16 to a receiver via a multiplexer means 4. The receiver uses a destination collation means 20 to input the information 16 to a key collation means 25 when the destination code 9 in the key control information 16 is its own device identifier 1. The collation means 25 uses a key information delete means 26 to delete the relevant key identifier 7 and the key information 6 in pairs from a key storage buffer 21 when the same key identifier as the key identifier 7 sent in the key control information 16 is in existence in the key storage buffer 21.