Patent ID: 7395429

Claim:
A mutually authenticating method for mutually authenticating a reproducing apparatus and an information processing apparatus, the reproducing apparatus including a reproducing portion for reading content information from a recording medium including revocation information and information unique to the recording medium, the revocation information used to determine whether or not an electronic device is illegal, the reproducing apparatus configured to transmit and receive the content information to and from the information processing apparatus for processing the content information, the mutually authenticating method comprising: causing the reproducing apparatus to determine whether or not the reproducing apparatus itself should be invalidated using information that represents the reproducing apparatus and the revocation information; causing the information processing apparatus to determine whether or not the information processing apparatus itself should be invalidated using the information that represents the information processing apparatus and the revocation information; and causing the reproducing apparatus and the information processing apparatus to mutually authenticate each other using both first key information generated when a determined result of the reproducing apparatus does not represent that the reproducing apparatus should be invalidated and second key information generated when a determined result of the information processing apparatus does not represent that information processing apparatus should be invalidated.