Copyright protection system, recording device, and reproduction device

A reproduction device for reproducing encrypted content recorded on a recording medium removable from said reproduction device, the removable recording medium having an unrewritable area in which a media number for identifying the removable recording medium is recorded,

• wherein the encrypted content, an encrypted content key, and license information have been recorded on the removable recording medium by a recording device storing a content key, the content key to be used to decrypt the encrypted content,
• wherein the encrypted content key recorded on the removable recording medium is the content key encrypted by the recording device based on a first master key assigned to the recording device, and the license information recorded on the removable recording medium is based on the media number and the content key,
• said reproduction device comprising:
• a second master key storing unit configured to store a second master key assigned to said reproduction device;
• a computing unit configured to obtain the media number from the unrewritable area and the encrypted content key that are recorded on the removable recording medium loaded to said reproduction device, and generate reference license information based on the media number and the encrypted content key;
• a comparing unit configured to (i) obtain the license information from the removable recording medium and the reference license information from said computing unit, and (ii) compare the license information and the reference license information to determine whether or not the license information and the reference license information match each other, thereby determining whether or not at least one of (a) the removable recording medium loaded to said reproduction device is a copied medium, the copied medium having a different media number from the removable recording medium on which the encrypted content is recorded originally, and having recorded thereon copies of the license information, the encrypted content key, and the encrypted content, and (b) the content key has been tampered with;
• a decrypting unit configured to obtain the encrypted content and the encrypted content key from the removable recording medium, obtain the second master key stored in said master key storing unit, decrypt the encrypted content key by using the second master key, and decrypt the encrypted content by using the content key to generate decrypted content;
• a reproduction unit configured to reproduce the decrypted content;
• and
• a suppressing unit configured to suppress the reproduction of the decrypted content when said comparing unit determines that the license information does not match the reference license information.

A copyright protection method for use in a copyright protection system including a recording device for recording encrypted content on a recording medium loaded to the recording device, the recording medium being removable from the recording device, and a reproduction device for reproducing the encrypted content recorded on the removable recording medium, the removable recording medium having an unrewritable area in which a media number for identifying the removable recording medium is recorded, the recording device storing a first master key assigned to the recording device, and the reproduction device storing a second master key assigned to the reproduction device,

• wherein, in the recording device, the method comprises:
• encrypting a content key stored in the recording device based on the first master key stored in the recording device, the content key to be used to decrypt the encrypted content;
• obtaining the media number from the removable recording medium, and generating license information based on the media number and the content key;
• recording the license information, the encrypted content key, and the encrypted content on the removable recording medium;
• and
• wherein, in the reproduction device, the method comprises:
• obtaining a media number from an unrewritable area and an encrypted content key that are recorded on a removable recording medium loaded to the reproduction device, and generating reference license information based on the media number and the encrypted content key;
• obtaining the license information from the removable recording medium loaded to the reproduction device and the generated reference license information, and comparing the obtained license information and the generated reference license information to determine whether or not the obtained license information and the generated reference license information match each other, thereby determining whether or not at least one of (a) the removable recording medium loaded to the reproduction device is a copied medium, the copied medium having a different media number from the removable recording medium loaded to the recording device and having recorded therein copies of the license information, the encrypted content key, and the encrypted content, and (b) the content key has been tampered with;
• obtaining the encrypted content and the encrypted content key from the removable recording medium loaded to the reproduction device, decrypting the encrypted content key by using the stored second master key, and decrypting the encrypted content by using the content key to generate decrypted content;
• reproducing the decrypted content;
• and
• suppressing said reproducing of the decrypted content when said comparing determines that the obtained license information does not match the generated reference license information.

A reproduction method for reproducing encrypted content recorded on a recording medium removable from a reproduction device, the removable recording medium having an unrewritable area in which a media number for identifying the removable recording medium is recorded,

• wherein the encrypted content, an encrypted content key, and license information have been recorded on the removable recording medium by a recording device storing a content key, the content key to be used to decrypt the encrypted content,
• wherein the encrypted content key recorded on the removable recording medium is the content key encrypted by the recording device based on a first master key assigned to the recording device, and the license information recorded on the removable recording medium is based on the media number and the content key, and
• wherein said method comprises:
• storing a second master key;
• obtaining the media number from the unrewritable area and the encrypted content key from the removable recording medium loaded to the reproduction device, and generating reference license information based on the media number and the encrypted content key;
• obtaining the license information from the removable recording medium loaded to the reproduction device and the generated reference license information, and comparing the obtained license information and the generated reference license information to determine whether or not the obtained license information and the generated reference license information match each other, thereby determining whether or not at least one of (a) the removable recording medium loaded to the reproduction device is a copied medium, the copied medium having a different media number from the removable recording medium loaded to the recording device and having recorded therein copies of the license information, the encrypted content key, and the encrypted content, and (b) the content key has been tampered with;
• obtaining the encrypted content and the encrypted content key from the removable recording medium loaded to the reproduction device, decrypting the encrypted content key by using the second master key, and decrypting the encrypted content by using the content key to generate decrypted content;
• reproducing the decrypted content;
• and
• suppressing said reproducing of the decrypted content when said comparing determines that the obtained license information does not match the generated reference license information.

A reproduction program, stored on a computer-readable medium, for use in a reproduction device for reproducing encrypted content recorded on a recording medium removable from the reproduction device, the removable recording medium having an unrewritable area in which a media number that is for identifying the removable recording medium is recorded,

• wherein the encrypted content, an encrypted content key, and license information have been recorded on the removable recording medium by a recording device storing a content key, the content key to be used to decrypt the encrypted content,
• wherein the encrypted content key recorded on the removable recording medium is the content key encrypted by the recording device based on a first master key assigned to the recording device, and the license information recorded on the removable recording medium is based on the media number and the content key, and
• wherein the reproduction program causes the reproduction device to execute operations comprising:
• storing a second master key assigned to the reproduction device;
• obtaining the media number from the unrewritable area and the encrypted content key from the removable recording medium loaded into the reproduction device, and generating reference license information based on the media number and the encrypted content key;
• obtaining the license information from the removable recording medium loaded to the reproduction device and the generated reference license information, and comparing the obtained license information and the generated reference license information to determine whether or not the obtained license information and the generated reference license information match each other, thereby determining whether or not at least one of (a) the removable recording medium loaded to the reproduction device is a copied medium, the copied medium having a different media number from the removable recording medium loaded to the recording device and having recorded therein copies of the license information, the encrypted content key, and the encrypted content, and (b) the content key has been tampered with;
• obtaining the encrypted content and the encrypted content key from the removable recording medium loaded to the reproduction device, decrypting the encrypted content key by using the stored second master key, and decrypting the encrypted content by using the content key to generate decrypted content;
• reproducing the decrypted content;
• and
• suppressing said reproducing of the decrypted content when said comparing determines that the obtained license information does not match the generated reference license information.