Patent ID: 7219369

Claim:
An inner memory type tamper resistant microprocessor, comprising: a decryption unit configured to decrypt each one of a plurality of programs encrypted by different encryption keys; an internal memory configured to store the plurality of programs decrypted by the decryption unit, in plaintext in memory page units, resources thereof being managed by an operating system; a requested secret protection attribute maintaining unit configured to set and store a requested secret protection attribute requested for each access target memory page by a task, exclusively from other tasks, at a time of reading a program into memory pages and executing the program as the task; a memory secret protection attribute maintaining unit configured to store a memory secret protection attribute for each memory page, the memory secret protection attribute being reset by the operating system as occasion demands; a secret protection management unit configured to set the memory secret protection attribute in the memory secret protection attribute maintaining unit, for each access target memory page by the task, at a time of executing the task; and a memory protection unit configured to compare the requested secret protection attribute for each access target memory page stored in the requested secret protection attribute maintaining unit and the memory secret protection attribute for each access target memory page stored in the memory secret protection attribute maintaining unit, and refuse an access to each access target memory page when the requested secret protection attribute for each access target memory page and the memory secret protection attribute for each access target memory page do not coincide.