| 摘要 |
A user terminal has a file exchanging capability provided with a transmission control unit, a reception control unit, and an entry unit. As the transmitting capability by the transmission control unit, the entry unit makes an entry in an external specific server. Unless a digital certificate can be obtained for an individual public key through the server, contents is unavailable. When contents are transmitted or enabled for transmission, the transmission control unit assumes that a signature has been placed without fail. The reception control unit checks the signature of the received contents, and controls the contents to be unavailable unless a correct signature has been placed. |
