Hitachi, Ltd.

Hitachi Chubu Software, Ltd.

Seiichi Susaki

Kazuo Takaragi

Ryoichi Sasaki

Kunihiko Miyazaki

Hiroshi Yoshiura

Tsutomu Matsumoto

Takeshi Matsuki

Hisashi Toyoshima

Mitsuru Iwamura

Katsuyuki Umezawa

Hiroki Uchiyama

Hiroshi Matsumoto

Tsukasa Saito

Toshiyuki Moritsu

Mizuhiro Sakai

Tsutomu Nakamura

Tadashi Kaji

Kuniaki Tabata

Satoru Tezuka

Hiroyuki Maezawa

Hirokazu Aoshima

Makoto Kitagawa

Shinobu Koizumi

Yasuhiko Mizuno

Akira Kito

Hideo Noyama

Seiji Miyazaki

Hisashi Umeki

Kunihito Takeuchi

Takashi Akaosugi

Kazuo Matsunaga

Hisanori Mishima

Kenzi Matsumoto

Toshiomi Kodama

Miwa Takahashi

Satoshi Mitsunaga

Shoji Moriyama

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

According to the present invention, techniques, including a method and system, for restoring and/or validating data and/or associated signature log entries are provided. One embodiment of the present invention provides a method for validating a restored message, having an entry generated in a signature log for a message, where the entry includes cryptographic information associated with the message. Next, when said message is lost, the restored message is generated responsive to a request; and the restored message is validated using the signature log. In another embodiment a method for validating a selected log entry by using a signature log having a plurality of recorded log entries is provided. The method includes: computing a cryptographic value for the selected log entry; and determining if the cryptographic value is part of another recorded log entry.

Method and system for recovering the validity of cryptographically signed digital data

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 certificate management method is provided whereby a plurality of service providers have different reliable certificate authorities and, when certificates issued from the certificate authorities are implemented into a smart card, merely by revoking the certificate issued from the certificate authority on which the first service provider relies, all other implemented certificates can be revoked, and the certificates can be individually revoked. A system for implementing the method is provided. The certificate authorities n (n&#x2267;2) issue a certificate n by using a private key n' corresponding to certificate n&#x2032; generated by using a certificateissued from a certificate authoritywhich has previously been installed in the smart card and a corresponding private key. Thus, the issued certificates have a hierarchical chain relation. When the user wants to revoke all certificates, the certificateissued from the certificate authorityis revoked.

Certificate management system and method

A Smart card-based service providing system and method, in which a service application uses resources of a common application and which can easily cope with an addition of a service application into the Smart card and thereby efficiently utilize valuable resources of the Smart card, is provided. A management application specially designed for access control is installed in the Smart card to solely manage access management information. A management of or a decision on an access right is not performed by the service application or the common application but by the management application. When a new application is added to the Smart card, the service provider device receives a permission to update access management information beforehand from the card issuer device and, based on the permission, updates the access management information.

Information processor-based service providing system and method

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

According to the present invention, techniques, including a method and system, for restoring and/or validating data and/or associated signature log entries are provided. One embodiment of the present invention provides a method for validating a restored message, having an entry generated in a signature log for a message, where the entry includes cryptographic information associated with the message; Next, when said message is lost, the restored message is generated responsive to a request; and the restored message is validated using the signature log. In another embodiment a method for validating a selected log entry by using a signature log having a plurality of recorded log entries is provided. The method includes: computing a cryptographic value for the selected log entry; and determining if the cryptographic value is part of another recorded log entry.

Digital signature generating method and digital signature verifying method

This invention provides a method for identifying a purchaser who purchased content from which an illegal copy was produced. A provider system encrypts purchased by the purchaser using a public key of a purchaser system and sends the encrypted content to the purchaser system. The purchaser system creates a digital signature of the content with the use of a private key of its own and embeds the created digital signature into the received content. When an illegal copy is found, the provider system verifies the digital signature, embedded in the illegal copy as a digital watermark, to identify the purchaser who purchased the content from which the illegal copy was produced.

Digital data authentication method

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 completeness of the object program is confirmed and the user and the object program permit use of the services in advance, which makes it possible to prevent a client object which is down-loaded to a client terminal through a network and executed therein from carrying out unjustified processing (not intended by a user using the client terminal) by using authority of the user.

Distributed object system and service supply method therein

Certification and authentication services (electronic information signing and archiving services) are given when electronic commerce is carried out in an open network such as Internet. A system has a service supplying unit and service receiving units which are connected to one another through a communication network. In the system, the service supplying unit transmits contract information including a content of a contract to the service receiving units of the service receivers. Each of the service receiving units having received the contract information prepares one party-signed contract information in which the contract information is digitally signed by the service receiver and transmits the one party-signed contract information to the service supplying unit. The service supplying unit receives the one party-signed contract information transmitted from each of the service receiving units, synthesizes a plurality of received copies of one party-signed contract information into a single document, prepares contract information signed by the service supplier in which the document is digitally signed by the service supplier, and archives the prepared service supplier-signed contract information and transmits such contract information to each of the service receiving units.

Electronic certification authentication method and system

A client-server system is provided in which access to a service by a user can properly be controlled, even if an approval by another user is required for receiving the service. First, the server,executes a log-in processing by using a user identifier and password transmitted from the client terminal,, and a user control file,. Next, the server,executes a service control by using a service supply request transmitted from the client terminal,and a service control file,provided with the server. When the server determines that an approval by another user is required for providing the service, the server executes the approval request to the client terminal,that the concerned user uses. When the reply to the approval request is affirmative, the server executes the processing in accordance with the foregoing service supply request. When the reply is negative, the server informs to the user who made the foregoing service supply request that the approval is rejected.

Client-server system for controlling access rights to certain services by a user of a client terminal

This invention provides a method for identifying a purchaser who purchased content from which an illegal copy was produced. A provider system encrypts a content purchased by the purchaser using a public key of a purchaser system and sends the encrypted content to the purchaser system. The purchaser system creates a digital signature of the content with the use of a private key of its own and embeds the created digital signature into the received content. When an illegal copy is found, the provider system verifies the digital signature, embedded in the illegal copy as a digital watermark, to identify the purchaser who purchased the content from which the illegal copy was produced.

In a terminal which received an electronic document with at leastone digital signature, when a user changes the contents of the received electronic document, a new digital signature is produced by enciphering signature data by using a secret key of the user, the signature data including a hash total of the document of a new version, personal information of the user (signatory), and version management information necessary to restore an electronic document of a former version from the electronic document of the new version. The new digital signature and the new version electronic document version are transmitted together with the received digital signature to a next person on a document circulating route.

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Yokohama, Japan

Seiichi Susaki