| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve the following problem: when a converted content is created by converting compression formats and the like of the content, an original content is deleted to prevent copyright infringement, and the original content cannot be restored from the converted content, the original content cannot be used again. <P>SOLUTION: The original content and the converted content obtained by converting the original content are encoded with an identical content key. A license including the content key and conditions of use, such as a use period, is recorded in an access-limited area. When the converted content is used by an external storage medium, a copy of the original license is created, a period of use of the copy is changed into a period of use of the converted content designated by the user, and output to the external storage as a converted content license. At the same time, the period of use of the original content is rewritten so that it may not overlap the period of use defined by the conversion license. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
