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:
Dec. 03, 2002
Filed:
Dec. 04, 1998
Yasuhiro Nakamura, Tokyo, JP;
Tokyo Electron Device Limited, Yokohama, JP;
Abstract
A flash memory includes an encoded cryptographic key “k” stored therein. A protected ROM, an external access to which is inhibited, includes a decoding program stored therein to decode the cryptographic key “k”. The cryptographic key “k” is decoded by using the decoding program. With the cryptographic key “k” as decoded, data is encrypted and stored in the flash memory. Data read out from the flash memory is output after decrypted with the cryptographic key “k.” In order to check an area having the decoding program stored therein, data which forms the decoding program is processed by using a hash function stored in the ROM, and a processing result and an expected value are compared with each other. When the processing result and the expected value matches with each other, the aforementioned area is determined as being in a normal condition.