Patent ID: 7603566

Claim:
A microprocessor executing a program including a plurality of processes, the microprocessor comprising: a first information acquiring unit which acquires, from outside the microprocessor, second process identification information for identifying a second process to be executed by a first process and first authentication information for authenticating the second process; a first information holding unit which holds the second process identification information, the first authentication information and a program key so that the second process identification information, the first authentication information and the program key are associated with each other; a second information acquiring unit which acquires the second process identification information from the first information holding unit, and which acquires the first authentication information as second authentication information for authenticating the second process, which is associated with the program key or is calculated by using the program key, from the first information holding unit, when the first process is executed; a second information holding unit which denies access from outside the microprocessor, and holds the second process identification information and the second authentication information so that the second process identification information and the second authentication information are associated with each other; and a switching authorization unit which compares, upon issuance of an instruction for switching from the first process to the second process, the first authentication information held on the first information holding unit at the time when the instruction is issued with the second authentication information, and allows, when the first authentication information and the second authentication information match, switching from the first process to the second process.