| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To increase the capacity of a storage device by automatically deleting content that cannot be reproduced. <P>SOLUTION: With reference to use conditions of a content key, when the encrypted content is unable to be decrypted by using the content key. because of, for example, expiration of a playback period, the content key and the content are deleted from the storage device to increase available storage capacity. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
