The inventive data processing apparatus initially generates verifying values for verifying integrity of contents data stored in a memory device, then stores the verifying values in correspondence with contents data, and then, using the verifying values, the data processing apparatus proves the act of tampering with the relevant contents data, where the verifying values are generated and stored in a memory device per category of contents data. Each of the categories is preset based on a controlling entity of enabling key blocks (EKB) which encipher and provide a contents key (Kcon) provided as a key for enciphering the kinds of categories or contents data. Because of this arrangement, it is possible to effectively and independently executes the process for probing the act of tampering with contents data per controlling entity of the enabling key blocks (EKB) for example.