COMPOSITE SYSTEM, TARGET KEY SUPPLYING SYSTEM, AND BROADCAST RECEIVING DEVICE

摘要

PROBLEM TO BE SOLVED: To shorten time till viewing becomes possible in a broadcast area after move in the case where a receiving device for digital television broadcasting has been moved across broadcast areas where receivable broadcast stations are different.SOLUTION: In a target key supplying system 200, a target key collection device 210 collects the latest target key (work key or device key) of each broadcast station. A target key distribution device 250 distributes the latest target key of each broadcast station collected by the target key collection device 210 to at least receiving devices situated outside the receivable area of the broadcast station via a communication network 190 different from a broadcast network. When the target key received from the target key distribution device 250 is newer than the target key held by themselves, receivers 1-9 update the target key held by themselves with the target key received from the target key distribution device 250.