Patent ID: 8171566

Claim:
A content playback device for playing back a digital content, the content playback device comprising: a processor device; an information acquisition unit operable to acquire a content playback program and a digital signature generated for the content playback program from a recording medium in which the digital content, the content playback program, and the digital signature are recorded, the content playback program being a computer program to be used for playing back the digital content, and the digital signature having an official release type or a test release type as a signature type; a medium type judgment unit operable to judge whether the recording medium is read-only; a signature verification unit operable to perform verification of the digital signature acquired by the information acquisition unit; a signature type judgment unit operable to judge, using the processor device, whether the digital signature has the official release type or the test release type; and a playback permission determination unit operable to: (i) prohibit performing processing relating to playback of the digital content by execution of the content playback program if the verification of the digital signature is successful, if the signature type of the digital signature is the official release type, and if the recording medium is judged not to be read-only; and (ii) permit performing the processing relating to playback of the digital content by execution of the content playback program if the verification of the digital signature is successful, if the signature type of the digital signature is the test release type, and if the recording medium is judged not to be read-only.