Patent ID: 7298845

Claim:
A digital content protection system that enables a digital content to be used and includes a recording medium apparatus having a storage area for holding digital content information and an access apparatus that reads information from and writes information into the storage area, the digital content protection system operating according to the following phases: an authentication phase where the recording medium apparatus secretly transmits an inherent key to the access apparatus, and the recording medium apparatus and the access apparatus perform mutual authentication using the inherent key, the inherent key being information that is unique to the recording medium apparatus; and a content transfer phase, performed only when the recording medium apparatus and the access apparatus have successfully authenticated each other, where the access apparatus either (a) encrypts a digital content using the secretly transmitted inherent key and sends the encrypted digital content to the recording medium apparatus or (b) receives an encrypted digital content from the recording medium apparatus and decrypts the encrypted digital content using the secretly transmitted inherent key, wherein the recording medium apparatus includes a first calculation means, and the access apparatus includes a first authentication information generating means and a first authentication means, wherein while the access apparatus judges whether the recording medium apparatus is legitimate in the authentication phase, the first authentication information generating means generates first authentication information and outputs the first authentication information to the recording medium apparatus, the first calculation means receives the first authentication information, generates first calculated authentication information by performing a first calculation on the received first authentication information using the inherent key, and outputs the first calculated authentication information to the access apparatus, and the first authentication means judges whether the recording medium apparatus is legitimate from the first authentication information and the first calculated authentication information using the secretly transmitted inherent key.