Patent ID: 7275161

Claim:
A data processing system that includes a data processing device and a recording medium that perform mutual authentication, and permits transfer of useful data only when the data processing device and the recording medium authenticate each other as being legitimate, the data processing device comprising: a medium authentication data storage unit operable to store first medium authentication data, and second medium authentication data generated by applying a predetermined encryption to the first medium authentication data; a medium authentication data transmission unit operable to transmit the first medium authentication data to the recording medium; an encrypted data reception unit operable to receive first encrypted data that has been generated by the recording medium by applying an encryption included in the recording medium to the transmitted first medium authentication data; a medium authentication unit operable to judge whether the received first encrypted data and the stored second medium authentication data are identical, and when the judgement is positive, authenticate the recording medium as being legitimate; a first device authentication data reception unit operable to receive first device authentication data from the recording medium; a device authentication data storage unit operable to store second device authentication data generated by applying the predetermined encryption to the first device authentication data; and a second device authentication data transmission unit operable, when the first device authentication data reception unit receives the first device authentication data, to transmit the stored second device authentication data to the recording medium, and the recording medium comprising: a medium authentication data reception unit operable to receive the first medium authentication data from the data processing device; a first encryption unit operable to generate the first encrypted data by applying the encryption included in the recording medium to the received first medium authentication data; an encrypted data transmission unit operable to transmit the generated first encrypted data to the data processing device; a device authentication data output unit operable to output the first device authentication data; a first device authentication data transmission unit operable to transmit the output first device authentication data to the data processing device; a second encryption unit operable to generate second encrypted data by applying the encryption to the output first device authentication data; a second device authentication data reception unit operable to receive the second device authentication data from the data processing device; and a device authentication unit operable to judge whether the received second device authentication data and the generated second encrypted data are identical, and when the judgement is positive, authenticate the data processing device as being legitimate.