Abstract: A tamper resistant microprocessor has a task state table for assigning a task identifier to a task that can take a plurality of states, and storing a state of the task in correspondence to the task identifier; a task register for storing the task identifier of a currently executed task; an interface for reading a program stored in a form encrypted by using a program key at an external memory, in units of cache lines, when a request for the task is made; an encryption processing unit for generating decryption keys that are different for different cache lines, according to the program key, and decrypt a content read by the interface; a cache memory formed by a plurality of cache lines each having a tag, for storing the task identifier corresponding to a decryption key used in decrypting each cache line in the tag of each cache line; and an access check unit for comparing the task identifier stored in the tag of each cache line with a value of the task register, and discarding a content of each cache line when t

Abstract: In a tamper resistant microprocessor, a processor temporary key in a form of an encryption key of a secret key cryptosystem is generated at every occasion of an initialization of the microprocessor, according to a random number that is generated according to parameters used inside the microprocessor and that is different for different microprocessors. Then, the context is encrypted by using the processor temporary key and saved into the external memory, and recovered from the external memory and decrypted by using the processor temporary key.

Abstract: In a microprocessor that internally has a microprocessor specific secret key, a key management unit is provided to carry out a key registration for reading out from an external memory a distribution key that is obtained in advance by encrypting the instruction key by using a public key corresponding to the secret key, decrypting the distribution key by using the secret key to obtain the instruction key, and registering the instruction key in correspondence to a specific program identifier for identifying the program into a key table, and to notify a completion of the key registration to the processor core asynchronously by interruption when the key registration is completed.

Abstract: In a microprocessor, a program key for decrypting a program and a data key for encrypting/decrypting data processed by the program are handled as cryptographically inseparable pair inside the microprocessor, so that it becomes possible for the microprocessor to protect processes that actually execute the program, without an intervention of the operating system, and it becomes possible to conceal secret information of the program not only from the other user program but also from the operating system.

Abstract: In a program distribution system including a source file sending device, an encrypted program distribution device and an execution file receiving device, which are interconnected through a network, the encrypted program distribution device examines the source file received from the source file sending device, and when the source file passes an examination, an execution file of the program is generated from the source file, a public key which is either unique to an execution file receiving device or unique to a processor of the execution file receiving device is received from the execution file receiving device through the network, at least a part of the execution file is encrypted by using the public key, and the execution file is sent to the execution file receiving device.

Abstract: Under a multi-task environment, a tamper resistant microprocessor saves a context information for one program whose execution is to be interrupted, where the context information contains information indicating an execution state of that one program and the execution code encryption key of that one program. An execution of that one program can be restarted by recovering the execution state of that one program from the saved context information. The context information can be encrypted by using the public key of the microprocessor, and then decrypted by using the secret key of the microprocessor.

Abstract: A scheme for distributing executable programs through a network from a program distribution device to a client device having a tamper resistant processor which is provided with a unique secret key and a unique public key corresponding to the unique secret key in advance is disclosed. In this scheme, a first communication path is set up between the program distribution device and the client device, and a second communication path directly connecting the program distribution device and the tamper resistant processor is set up on the first communication path. Then, the encrypted program is transmitted from the program distribution device to the tamper resistant processor through the second communication path.

Abstract: A radio terminal or gateway capable of executing the AV/C protocol on the datalink protocol which starts communications after setting up a logical channel on a radio network is disclosed. The radio terminal or gateway transfers data packets according to the stored correspondence information among the protocol identifier, the channel identifier that is set up for the radio terminal or gateway, and the channel identifier that is set up for a correspondent radio terminal or gateway, where the correspondence information is obtained through an exchange of signaling packets containing the channel identifier indicating a logical channel that is set up for transferring the data packets and the protocol identifier indicating the AV control protocol.