| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a system capable of reproducing backup data even when a main storage medium is fatally destroyed and data cannot be read and written. <P>SOLUTION: Contents enciphered by a first title key and a second title key enciphered by the first title key by using a first device key are stored in a main storage medium 19. The contents and the second title key are stored in a storage medium 64 for backup. When moving/deleting the contents from the main storage medium 19, a second device key is formed. A third title key is formed by the second device key and the content of the storage medium 64 for backup is rewritten. In this constitution, the contents can be returned to the original main storage medium from the storage medium for backup and the contents can be reproduced. <P>COPYRIGHT: (C)2004,JPO |
