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. 19, 2023
Filed:
Dec. 06, 2017
Nippon Telegraph and Telephone Corporation, Chiyoda-ku, JP;
NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Chiyoda-ku, JP;
Abstract
The present invention makes it possible to improve confidentiality. A communication terminal stores a session key shared with other communication terminals (S). The communication terminal makes a pair of an index generated by using the session key for a character string relating to a message and a message identifier, and transmits it to a server apparatus (S). The server apparatus stores the pair of the index and the message identifier (S). The communication terminal generates, when the session key is updated, a re-encryption key with a session key before update and a session key after update (S). The server apparatus updates, by using the re-encryption key, the stored index to an index generated by using the session key after update (S). The communication terminal encrypts a search keyword with the session key to generate a search query (S). The server apparatus extracts a message identifier of which the index matches the search query (S).