Patents by Inventor Youichi Takashima

Youichi Takashima 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).

  • Method and system for digital information protection
    Patent number: 5701343
    Abstract: A digital information protection scheme using an improved security protocol. In a system in which a user makes an access to a digital information provided by an information center by connecting a computer card owned by the user to an information terminal device connected with the information center, a work key for encrypting a desired digital information is delivered from the information center to the computer card through the information terminal device, and the work key is registered in the computer card; the desired digital information encrypted by the work key is delivered from the information center to the information terminal device; and an encrypted digital information delivered from the information center is decrypted at the information terminal device by using the work key registered in the computer card, and a decrypted digital information is provided to the user at the information terminal device.
    Type: Grant
    Filed: November 29, 1995
    Date of Patent: December 23, 1997
    Assignee: Nippon Telegraph & Telephone Corporation
    Inventors: Youichi Takashima, Shinji Ishii, Kiyoshi Yamanaka