Hitachi, Ltd.

Mitsuru Iwamura

Ryoichi Sasaki

Kunihiko Miyazaki

Tsutomu Matsumoto

Seiichi Susaki

Kazuo Takaragi

Hiroshi Yoshiura

Takeshi Matsuki

Toshiyuki Moritsu

Mizuhiro Sakai

Hisashi Toyoshima

Hirokazu Aoshima

Hideo Noyama

Hisanori Mishima

Kunihito Takeuchi

According to the invention, techniques for authenticating that a digitally signed document is genuine. Specific embodiments according to the present invention can determine whether a digital signature was generated by a digital signature generator, or if the digital signature was generated by a third party posing as the digital signature generator. Specific embodiments can provide independent verification of digital signer identity based upon prior signed messages, time/date stamps, and the like. Techniques according to the present invention can be embodied in methods, apparatus, computer software and systems.

Digital signing method

An electronic document authenticity assurance technique and an information disclosure system both of which can compatibly realize the assurance of the authenticity of disclosure documents and the deletion of information inappropriate for disclosure. An electronic document is divided into constituent elements and an electronic signature is affixed to an arbitrary subset of a set including all the constituent elements. Otherwise, an electronic signature is affixed to data obtained by binding each of the constituent elements to information specifying the relationship between a respective one of the constituent elements and the structure of the electronic document. Otherwise, the hash values of the respective constituent elements are calculated and an electronic signature is affixed to data obtained by binding the calculated hash values together. Otherwise, random numbers generated for the respective constituent elements are bound together, then the hash values of the respective random-numbered constituent elements are calculated, and then an electronic signature is affixed to data obtained by binding the calculated hash values together.

Electronic document authenticity assurance method and electronic document disclosure system

A time stamp generating system has a time distribution server for generating time data depending on time and a user PC for holding time certification objective digital data. The time distribution server generates time data corresponding to a time point and distributes the time data. The user PC calculates time stamp generating data by using the time certification objective data as an input, acquires the time data generated by the time distribution server, and processes the time data on the basis of the time stamp generating data to obtain a time stamp.

Time stamp generating system

Digital signature generating method and digital signature verifying method

An authentication system for authenticating a particular individual using a recording medium containing information for identifying the individual has a recording medium issuing apparatus including, a database for storing a feature value usable for identification of the individual to be authenticated with the recording medium, means for managing the database to store the feature value of the individual to be authenticated with the recording medium and for generating search information to retrieve the feature value of the individual from the database, means for generating cryptographic information by encrypting the thus generated search information using a private key based on public key cryptography, and means for recording the thus generated cryptographic information and certification information concerning the individual onto the recording medium; and a recording medium authenticating apparatus including, means for decrypting the cryptographic information recorded on the recording medium using a public key paired with the private key to decode the search information, and means for searching the database using the thus decoded search information to retrieve the feature value of the individual.

Method of physical individual authentication and system using the same

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Tokyo, Japan

Mitsuru Iwamura