Patents by Inventor Tadashi Kaji

Tadashi Kaji has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20050226424
    Abstract: Both a management server and a validation server are installed. Both a terminal and a terminal register setting information which is usable in an encrypted communication in the management server. When carrying out the encrypted communication, the management server searches the registered setting information for coincident setting information. The management server generates keys for the encrypted communications which can be used by the terminals, and delivers these generated keys in combination with the coincident setting information. The management server authenticates both the terminals in conjunction with the validation server. Since the terminals trust such results that the management server has authenticated the terminals respectively, these terminals need not authenticate the respective communication counter terminals.
    Type: Application
    Filed: September 1, 2004
    Publication date: October 13, 2005
    Inventors: Osamu Takata, Takahiro Fujishiro, Tadashi Kaji, Kazuyoshi Hoshino
  • Publication number: 20050081037
    Abstract: A validation authority for certificates searches for and verifies paths and certificate revocation lists periodically, and classifies the paths into valid paths and invalid paths in accordance with the results of the validations, so as to register the paths in databases beforehand. Besides, in a case where a request for authenticating the validity of a certificate has been received from an end entity, the validation authority judges the validity of the public key certificate by checking in which of the valid-path database and the invalid-path database a path corresponding to the request is registered. On the other hand, in a case where the path corresponding to the validity authentication request is not registered in either of the databases, the validity of the public key certificate is authenticated by performing path search and validation anew.
    Type: Application
    Filed: March 1, 2004
    Publication date: April 14, 2005
    Inventors: Yoko Kumagai, Takahiro Fujishiro, Tadashi Kaji, Shingo Hane, Hitoshi Shimonosono
  • Publication number: 20040255116
    Abstract: The present invention provides a technology for verifying the validity of an electronic document by using a signature affixed to the electronic document at the time of its creation even if the electronic document is partially rendered private at the time of its disclosure. An target electronic document is divided into two or more partial documents having an arbitrary or fixed length. This division is effected by using a tag of XML or other markup language so as to provide versatility or by adding a dedicated delimiter for division. The system has a signature function. The signature function uses a signature technique for generating the information for verifying the validity of each of the partial documents, and validating a signature affixed to the electronic document to confirm the validity of the whole electronic document by affixing a signature to the aggregate of the generated validity confirmation information.
    Type: Application
    Filed: August 20, 2003
    Publication date: December 16, 2004
    Inventors: Shingo Hane, Takahiro Fujishiro, Tadashi Kaji, Yoko Kumagai, Junichi Takeuchi
  • Publication number: 20040111609
    Abstract: If a CRL is cached for an increased speed of a certificate validation process, when a certification authority issues a CRL in an urgent situation, the accuracy of the certificate validation result cannot be secured because the cached CRL is not the latest one. This problem is solved as follows. When it issues a CRL, the certification authority sends a CRL issuance notification to certificate validation servers. The certificate validation servers that received the CRL issuance notification cache the latest CRL. Thus, the accuracy of the certificate validation result can be secured.
    Type: Application
    Filed: June 9, 2003
    Publication date: June 10, 2004
    Inventors: Tadashi Kaji, Takahiro Fujishiro, Yoko Kumagai, Shingo Hane, Hiromi Nagano
  • Publication number: 20030084294
    Abstract: A system that can reduce possibility of outflow of private information in authentication of a user of an information terminal. A management apparatus has a user certificate DB in which a user certificate is registered in association with certificate identification information. Further, the management apparatus reads the user certificate associated with the certificate identification information sent from a service providing apparatus, from the user certificate DB, and judges whether the user certificate satisfies certain Web browsing conditions, to determine approval or denial of browsing the Web page concerned. Then, the management apparatus sends the service providing apparatus approval or denial information indicating the determination result.
    Type: Application
    Filed: August 30, 2002
    Publication date: May 1, 2003
    Inventors: Hirokazu Aoshima, Tadashi Kaji, Katsuyuki Umezawa, Hitoshi Matsushima, Hiroshi Yoshiura, Hisashi Toyoshima
  • Publication number: 20020138322
    Abstract: Subjects data indicating the names and positions of personnel and position hierarchy data indicating the hierarchical relations between positions are defined beforehand. When an activity status changes, activity status data is updated. When an activity is completed, history data is updated. Also, rules data is defined to indicate rules based on combinations of this data that specify personnel that cannot carry out activities (denied users), positions that cannot carry out activities (denied positions), personnel that must carry out activities (required users), and positions that must carry out activities (required positions). When a workflow server assigns personnel to activities, a security server is used to provide access control. The security server uses history data, activity status data, subjects data, position hierarchy data, and rules data to determine denied users, denied positions, required users, and required positions, and evaluates access permissions and determines assignment candidates.
    Type: Application
    Filed: March 23, 2001
    Publication date: September 26, 2002
    Inventors: Katsuyuki Umezawa, Tadashi Kaji
  • Patent number: 6327658
    Abstract: A distributed object system comprising at least one object distributing server, at least one client terminal and at least one server object execution server according to the present invention, including: an object distributing server for storing an object program to which an electronic signature is affixed; a client terminal including means for down-loading the object program from the object distributing server, means for verifying the electronic signature affixed to the object program, means for executing the client object program when the completeness of the object program is confirmed and the user of the client terminal beforehand permits execution of the client object program which is electronically signed by a signatory, and means for transmitting the electronic signature affixed to the object program to a server object execution server; and a server object execution server including means for verifying the signature received, and means for supplying services to the user of the client terminal when the c
    Type: Grant
    Filed: November 4, 1998
    Date of Patent: December 4, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Seiichi Susaki, Katsuyuki Umezawa, Tadashi Kaji, Satoru Tezuka, Ryoichi Sasaki, Kuniaki Tabata, Takashi Akaosugi, Akira Kito