Abstract: A rating browser may easily confirm the validity or invalidity of an evaluation result of a rating target disclosed over a WWW system, as to whether the evaluation result is truly based on the evaluation conducted by a rating performer.

Abstract: In a signature generating method where not necessarily all of a plurality of signature generating devices work together each time to generate signatures, the present invention seeks to correctly and securely reflect data relating to previous signatures.

Abstract: 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.

Abstract: In an access control method for use with a system including a client, a www server, and a ticket granting server, the www server has a server policy defining an access allowance condition and sends a server policy to the client having requested an access. The ticket granting server obtains, in response to a request and the server policy sent from the client, personal information from a personal information database, authenticates the personal information, and sends it as a ticket to the client. The client sends an access request with the ticket to the www server. The www server allows the client the access when the ticket matches the server policy.

Abstract: 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.

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

Abstract: 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.

Abstract: 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 2 executes a log-in processing by using a user identifier and password transmitted from the client terminal 2, and a user control file 202. Next, the server 2 executes a service control by using a service supply request transmitted from the client terminal 1 and a service control file 42 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 1 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.

Abstract: 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.

Abstract: 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.

Abstract: Method and system which permit, among a plurality of terminals, group cipher communication from a desired terminal to a number of desired terminals while ensuring safety of security. A plurality of secret values called master keys which are common to a predetermined subset of IC cards are stored in an IC card. A terminal initially starting communication generates a destination indicator to transmit it to other terminals, selects one of a plurality of master keys stored in an IC card on the basis of the destination indicator, generates a group key by using the selected master key, and performs encipherment and decipherment of a communication message by using the generated group key to carry out broadcast.