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:
Aug. 23, 2016
Filed:
Mar. 19, 2014
Kabushiki Kaisha Toshiba, Minato-ku, JP;
Toshiba Solutions Corporation, Kawasaki-shi, JP;
Ryotaro Hayashi, Kawasaki, JP;
Tatsuyuki Matsushita, Kawasaki, JP;
Yoshihiro Fujii, Tokyo, JP;
Takuya Yoshida, Inagi, JP;
Koji Okada, Tokyo, JP;
KABUSHIKI KAISHA TOSHIBA, Minato-ku, JP;
TOSHIBA SOLUTIONS CORPORATION, Kawasaki-shi, JP;
Abstract
A server apparatus according to an embodiment generates a random number on receiving from a user apparatus a notification showing that a re-encryption key should be updated, and calculates re-encryption key data on the basis of the re-encryption key stored and the random number generated. The server apparatus transmits the re-encryption key to the user apparatus and receives, from the user apparatus, the user private key not updated yet and re-encryption key updating data calculated from the re-encryption key data on the basis of the user private key updated. The server apparatus calculates the re-encryption key updated, on the basis of the re-encryption key updating data and the random number, and replaces the re-encryption key stored in the storage device with the updated re-encryption key.