| 摘要 |
PROBLEM TO BE SOLVED: To provide a pay broadcast service of high security that can prevent unauthorized viewing which will not bear down a broadcast band, even if the number of subscribers is increased. SOLUTION: The information distributor of this invention broadcasts and distributes key information to the receiver, that receives broadcast and distributed and encrypted contents information to decode decodable contents information, on the basis of decoding control information including specific information to the receiver required for decoding the contents information and on the basis of the key information required for decoding the contents information, independently of the receiver, distributes individual control information for updating a part or all of the decoding control information stored in the receiver to the receiver in two-way communication, and broadcasts and distributes the individual control information, in the case the reception of the individual control information by the receiver is not confirmed. |
