Patent ID: 8140675

Claim:
A content reproduction apparatus which reproduces a digital content, the content reproduction apparatus comprising: a secret information storage unit including a memory operable to store a device key, the device key corresponding to the content reproduction apparatus, and the device key being stored in the secret information storage unit such that the device key cannot be accessed from outside of the content reproduction apparatus; a cryptographic processing unit operable to decrypt an encrypted digital content corresponding to the digital content, the encrypted digital content being encrypted using the device key stored in the secret information storage unit; an index information storage unit operable to store index information, the index information indicating the device key stored in the secret information storage unit, and the index information being stored in the index information storage unit such that the index information is accessed from outside of the content reproduction apparatus; a video output unit operable to connect to a display apparatus that is distinct from the content reproduction apparatus; a user identification information transmission unit operable to transmit user identification information to a user authentication server located outside of the content reproduction apparatus, the user authentication server performing user authentication based on the user identification information received from the user identification information transmission unit, and the user authentication server transmitting an instruction for outputting the index information from the index information storage unit, based on a result of the authentication performed by the user authentication server; an instruction receiving unit operable to receive, from the user authentication server, the instruction for outputting the index information from the index information storage unit; a video processing unit operable to convert the index information stored in the index information storage unit into a data format that is displayable on a screen of the display apparatus; and an index information output unit operable to output, via the video output unit, only the index information converted by the video processing unit to cause the display apparatus to display the index information converted by the video processing unit, the index information converted by the video processing unit being output to the display apparatus based on the instruction received by the instruction receiving unit.