Patent ID: 8296561

Claim:
A requesting device for requesting verification of authenticity of the requesting device itself from a verifying device, comprising: a storage unit storing a plurality of computer programs that are to run on the requesting device, the computer programs being hierarchically related to each other; a measuring unit, each time one of the plurality of computer programs is loaded, measuring an amount of characteristics of the one of the plurality of computer programs; a generation unit which is tamper-resistant and, while a computer program that is one of the plurality of computer programs is loaded, generating certification information reflecting amounts of characteristics of the computer program and other computer programs that have already been loaded and are required to run the computer program; an output unit outputting the generated certification information; a requesting unit sending a request for secret information to the verifying device; a receiving unit receiving either the secret information or an update program, depending on a result of a judgment which is made by the verifying device to confirm whether or not the requesting device is authentic; and an update unit, when the receiving unit has received the update program, updating the computer program stored in the storage unit in accordance with the received update program, wherein the generation unit includes a plurality of platform configuration registers for storing amounts of characteristics, and the generation unit receives a specification of one of the platform configuration registers from the verifying device, and generates the certification information in accordance with an amount of characteristics stored in the register indicated by the specification received, and wherein the secret information is an encrypted device key that was generated by encrypting a device key, the requesting device further comprises an encrypting unit, the receiving unit receives the encrypted device key when the verifying device has confirmed authenticity of the encrypting unit, the encrypting unit generates a double-encrypted device key by encrypting the received encrypted device key, based on the device identifier for identifying the requesting device, and the requesting device further comprises a device key holding unit holding the generated double-encrypted device key.