| 摘要 |
PROBLEM TO BE SOLVED: To provide a secret information changing system, a secret information changing 1st device, a secret information changing 2nd device, and a medium in which demerit caused by eliminating an illegal device can be made less than a conventional device. SOLUTION: A STB converting a received broadcasting radio wave to AV data and the like is provided with a receiving means 121, a change indication information detecting means 125 detecting only change indication information from a received signal, a secret function selecting means 128 adding contents of a secret function history information storing means 127 by indication of the change indication information detecting means 125, selecting a new secret function from a secret function storing means 126, and changing a secret function being used now to the other secret function, an authentication means 123 using the selected secret function, and the like, and a VTR device 140 connected with a transmitting line 160 is provided with a secret function indication information extracting means 146 detecting discrimination number information out of transmitted signals, extracting a corresponding secret function from a secret function storing means 145 and outputting it to an authentication means 142, a decoding means 143, and the like. |
