The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 09, 2011
Filed:
Jun. 30, 2008
Takehisa Kato, Fuchu, JP;
Takehisa Kato, Fuchu, JP;
Kabushiki Kaisha Toshiba, Tokyo, JP;
Toshiba Solutions Corporation, Tokyo, JP;
Abstract
A user apparatus cannot acquire as many distribution keys K, . . . as a threshold value, to restore a content encryption key K, unless it decrypts as many encrypted sub-content items as the threshold value after it has played back a sub-content item SC. The user apparatus monitors the state in which the sub-content is being played back. It outputs a warning when the sub-content is in fast-forwarding state or skipping state. If the playback state is not returned to one before the fast forwarding or skipping, in spite of the warning, the user apparatus will erase the distribution keys acquired in the fast-forwarding state or skipping state.