Patent ID: 7835993

Claim:
A license management device which manages a license, the license being information which indicates a right to use a content under a predetermined usage rule, said license management device comprising: a license type identifying unit programmed to identify a license type which represents whether or not a license includes a usage rule which requires updating each time a content is used; a license accumulation unit programmed to perform different accumulation processing, depending on whether or not the license includes a usage rule which requires updating each time a content is used; a unique information managing unit programmed to hold a unique key which is unique to said license management device; a domain information managing unit programmed to hold a domain key held in common with said device and another license management device within a domain that consists of a plurality of predetermined license management devices; a content decrypting/reproducing unit programmed to use the content in accordance with the usage rule included in the license; and a license-type change determining unit programmed to determine whether or not the license type identified by said license type identifying unit has changed due to the use of a content by said content decrypting/reproducing unit, wherein said license accumulation unit includes a license accumulation control unit programmed to encrypt the license, as the accumulation processing: by using the unique key, which is held by said unique information managing unit, in a case where the license includes the usage rule which requires updating each time a content is used; and by using the domain key, which is held by said domain information managing unit, in a case where the license does not include the usage rule which requires updating each time a content is used, the different accumulation processing is processing for accumulating the license encrypted by said license accumulation control unit, and said license accumulation control unit is programmed to; determine that the license type has changed due to updating the usage rule included in the license, and in response to the determined license type change, decrypt the license by using a key conforming to the type before the change, and then encrypt the license by using a key conforming to the type after the change.