Patent ID: 7353404
Filing Date: 2008-04-01
Classification: G06F

Abstract:
1. A microprocessor having a unique secret key and a unique public key corresponding to the unique secret key that cannot be read out to external, comprising: a reading unit configured to read out a plurality of programs encrypted by using different execution code encryption keys from an external memory; a decryption unit configured to decrypt the plurality of programs read out by the reading unit by using respective decryption keys; an execution unit configured to execute the plurality of programs decrypted by the decryption unit; a context information saving unit configured to save a context information for one program whose execution is to be interrupted, into a context information memory provided inside the microprocessor, or encrypt the context information by using the public key and save the encrypted context information into the external memory, the context information containing information indicating an execution state of the one program and the execution code encryption key by which the one program was encrypted when the one program was read out by the reading unit; and a restart unit configured to restart an execution of the one program by reading out the context information from the context information memory, and recovering the execution state of the one program by using the context information including the execution code encryption key, or reading out the encrypted context information from the external memory, decrypting the encrypted context information by using the secret key, and recovering the execution state of the one program from the decrypted context information, wherein the restart unit restarts the execution of the one program only when a decrypted execution code encryption key contained in the decrypted context information coincides with the execution code encryption key of the one program.