The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 09, 2008
Filed:
Sep. 30, 2002
Mikio Hashimoto, Kanagawa, JP;
Kensaku Fujimoto, Kanagawa, JP;
Kenji Shirakawa, Kanagawa, JP;
Kabushiki Kaisha Toshiba, Tokyo, JP;
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 the task identifier in the tag and the value of the task register do not coincide.