| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent unauthorized use of a digital content in a distribution system for a digital content with a utilization time limit. <P>SOLUTION: A token device 104 authenticating a user includes an encryption key to decrypt an encrypted digital content, a utilization time limit determining function 402, and a built-in clock 403. The determining function 402 determines the propriety of the use of the encryption on the basis of the time indicated by the clock 403. Before the digital content is reproduced, the encrypted digital content is decrypted inside the token device 104 to be transmitted to a terminal device 102. After the digital content is reproduced, it is erased. According to the configuration described above, the system can prevent the unauthorized use of the digital content. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
