Patent ID: 7599495

Claim:
A content delivery service terminal unit comprising: a user access content selecting unit which logs in to a user management control unit on the basis of authentication information and makes a content select request on the basis of a delivery content list; a medium linking content acquiring unit which acquires information about an information storage medium as medium information from the information storage medium at the content select request and sends the information to a content delivery service providing unit, receives an encrypted content key and encrypted content from the content delivery service providing unit, and writes them together into the writable area of the information storage medium in which the medium information has been written, or separately into the writable area of the information storage medium in which the medium information has been written and of another information medium; and a content presentation control unit which reads an arbitrary encrypted content and the corresponding encrypted content key from the information storage medium, decrypts the encrypted content key on the basis of the medium information or the medium information and a terminal device unique key information, and decrypts the encrypted content on the basis of the decrypted content key.