| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide restriction when content data is actually used for such as reproduction and to prevent unauthorized use of content data in a device which is not registered on an information providing side. <P>SOLUTION: When an operation request for playing back content data recorded in a user device 2 itself is outputted, the device 2 transmits present time information, device ID, content information and operation information to a service center 1 (steps S31 and S32), and generates a one-time password being valid only within limited time by using these information (step S33). The service center 1 generates the one-time password and an operation permission command from the information sent from the user device 2 and the present time information obtained in a self-clock part, and transmits them to the user device 2 (steps S34 and S35). The user device 2 compares the two one-time passwords. When they coincide, an operation (play-back) requested by the user is performed (steps S36 and S37). <P>COPYRIGHT: (C)2004,JPO&NCIPI |
