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:
Apr. 27, 2010
Filed:
Dec. 11, 2001
Masaaki Yamamoto, Yokohama, JP;
Yoshiaki Hiramatsu, Yokosuka, JP;
Tatsuaki Wakabayashi, Yokohama, JP;
Kazuhiro Takagi, Tokyo, JP;
Masaaki Yamamoto, Yokohama, JP;
Yoshiaki Hiramatsu, Yokosuka, JP;
Tatsuaki Wakabayashi, Yokohama, JP;
Kazuhiro Takagi, Tokyo, JP;
NTT DoCoMo, Inc., Tokyo, JP;
Abstract
Included are Gateway server GWS which clocks the precise present time, and portable phone MS which performs a packet communication through gateway server GWS and IP server W. Portable phone MS acquires the time information from gateway server GWS, at the time of starting communication with IP server W and corrects, on the basis of this time information, the clocking present time of its own portable phone MS so that it is more precise. In addition, portable phone MS decodes a public key certificate (an electronic certificate issued by Certificate Office C for the public key certificate of IP server W) using the public key of Certificate Office C. Then the portable phone MS judges whether it is within the validity period specified in the public key certificate, using the corrected present time of its own portable phone MS.