Abstract: A key exchange system method safely conceal secret information recorded on a blockchain. A first terminal includes a license issuing unit that generates a first transaction including a first public key, a first key storage region that retains a first secret key, and a first encrypting and decrypting unit that generates a common key using deal-specific information, a second public key, and the first secret key, and a second terminal includes a license requesting unit that generates a second transaction including the second public key, a second key storage region that retains a second secret key, and a second encrypting and decrypting unit that generates the common key using deal-specific information, the first public key, and the second secret key. The first encrypting and decrypting unit encrypts secret information using the common key. The second encrypting and decrypting unit decrypts the encrypted secret information using the common key.

Abstract: A data registration system of the present embodiment includes a control device 20 and a cooperating device 30. The control device 20 includes a communication unit 21 that receives a data registration request to which an electronic signature of a user is added, a verification unit 22 that verifies identity of the user, a transaction generation unit 23 that, if identity of the user is verified, takes out data included in the data registration request, transmits the data to the cooperating device 30 to store the data in the cooperating device 30, generates a transaction based on the data registration request, and adds an electronic signature to the transaction, the transaction including information for accessing the data stored in the cooperating device 30, and a blockchain control unit 24 that issues the transaction to a blockchain network. The cooperating device 30 includes a communication unit 31 that receives the data and a storage unit 33 that stores the data in association with the transaction.

Abstract: When an updated file that is an updated version of an original file is registered in a distributed file management system 100, a difference creation unit 222 creates a difference file between the original file and the updated file, a route object creation unit 223 creates a route object that includes an ID of the original file and an ID of the difference file, and a distributed file management client 11 causes the difference file and the route object to be registered in the distributed file management system 100.

Abstract: A permission terminal 4 includes a generation unit 423 that generates access information for content using a content public key of the content and a user public key of a browser of the content, and a registration unit 424 that registers the access information in a blockchain. The access information includes an aggregate public key in which the content public key and the user public key are aggregated, a message for the content, and a content signature in which the message is signed with a content private key corresponding to the content public key.

Abstract: A consensus is formed for a private database shared within a group. A block verification device includes: a private database shared within a group; a communication unit receiving a list of transactions from an overall leader device; a transaction processing unit executing the transactions identified based on the list and outputting the execution results; and a block processing unit generating a proposal including a list, a digest of the private database after execution of the transactions, and a private dataset included in the transactions. The communication unit transmits the proposal to another block verification device belonging to the same group, and transmits the list, the digest of the private database, and the digest of the private dataset to all the other block verification devices when it is determined that a consensus for the proposal is formed.

Abstract: Pieces of information on multiple file management systems are managed by one contract in a distributed ledger. An administrator terminal (1) includes: a file management system generation unit (122) that issues a contract generation transaction for generating, in blockchain data (B), a contract in which a network identifier that identifies a file management system (9) is associated with an identifier of a participant terminal (10) in a blockchain system (6), and notifying the participant terminal (10) of the network identifier and an identifier of the contract; and a file management control unit (123) that issues a registration transaction for registering, in the contract, connection information of the administrator terminal (1) in the file management system (9), acquires connection information of the participant terminal (10) in the file management system (9) from the contract, and establishes a P2P connection with the participant terminal (10) based on the acquired connection information.

Abstract: A history of data can be tracked easily on a blockchain. In a blockchain system, a distributed ledger 11 includes a state database that stores a state of a smart contract for each token. A user terminal 1 includes a transaction issue unit 13 that issues a transaction that updates a token. An approval terminal 2 includes an update unit 154 that updates the token in the state database, and a block generation unit 153 that generates the block including the transaction and causes the block and the updated state database to be reflected in the distributed ledger 11. The update unit 154 sets tracking data in the token in the state database, the tracking data including an update block number and token information on the token.

Abstract: A contribution degree of content according to a purchase situation of a content is calculated. A blockchain system includes a registration apparatus 1 and a contribution degree calculation apparatus 2. The registration apparatus 1 includes an acquisition unit 15 configured to acquire content purchase information and a transaction issuance unit 13 configured to issue a transaction including a purchaser ID and a content ID based on the content purchase information. The contribution degree calculation apparatus 2 includes a history acquisition unit 24 configured to acquire history information indicating that a purchaser with the purchaser ID purchases a different type of content associated with the content ID from a distributed ledger in which the transaction is reflected and a contribution degree calculation unit 25 configured to calculate a contribution degree of the content according to a purchase sequence of the content associated with the content ID by using the history information.

Abstract: A settlement system includes a service provider device 2 which transmits a template information transaction including a template of a transaction to a network 4 of a first blockchain, a user device which transmits, to the network 4 of the first blockchain, a payment information transaction that includes an electronic signature generated by using the template of the transaction and a payment amount, and a smart contract 41, wherein the smart contract 41 verifies the electronic signature by using the payment amount and the template of the transaction, the service provider device 2 generates a settlement transaction by using the template of the transaction, the electronic signature and the payment amount, and transmits the settlement transaction to a network 3 of a second blockchain, a plurality of output conditions are set to the template of the transaction, and the settlement transaction becomes usable when any one of the plurality of output conditions is satisfied.

Abstract: A history of data can be easily traced on a blockchain. A blockchain system includes a user terminal 1 and an approval terminal 2. The user terminal 1 includes a transaction issuing unit 13 that issues a transaction for updating a value of a variable of a smart contract. The approval terminal 2 includes a block generation unit 153 that generates a block including the transaction and updates the value of the variable, and reflects the block and an update block number of the block in which the value of the variable is updated to a distributed ledger 11 of a terminal of the blockchain system.

Abstract: Content data is registered in a file management system 8, an identifier of a user in the file management system 8 is registered in blockchain data B, and a right-holder terminal 1 includes a permission request receiving unit 122 that receives, from the file management system 8, permission request data for the content including an identifier of the user, a verification unit 123 that verifies that the identifier of the user registered in the blockchain data B corresponds to the identifier of the user included in the permission request data, and an permission issuing unit 124 that transmits, to the file management system 8, permission data for permitting a use of the content by the user.

Abstract: A proprietor terminal 1 stores state data Bs in which an identifier of a contract executed in a blockchain system 6, a hash value of control target file data that specifies content data managed by the contract, and an identifier of a proprietor and an identifier of a user of the content data in the file management system 9 are associated with one another, and includes a route object generation unit 123 that generates reference destination data R having the identifier of the contract and generates route object data Obj having the reference destination data R and a link name and the hash value of the control target file data.

Abstract: A blockchain is used to distribute a right to content data. A right holder terminal, an assignee terminal, and a blockchain control terminal stores a blockchain that is synchronized among the right holder terminal, the assignee terminal, and the blockchain control terminal. The blockchain includes a transaction set with a smart contract program for distributing the right. The blockchain control terminal includes a token issuance unit generating token data that includes match information for the content data and a type of right to be distributed, is set with an address of a right holder as owner information, and is identified by a token identifier, and registering the token data corresponding to the token identifier with the blockchain.

Abstract: A digital watermark is applied to a video to be distributed without re-encoding. A content distribution device 1 receives a content acquisition request to request video content, distributes the video content based on the content acquisition request, generates and distributes a watermark video with a watermark ID embedded, and causes watermark-video-related information including the watermark ID to be recorded, and a content playback device 2 transmits the content acquisition request, receives the video content and the watermark video, plays back and displays the video content, and superimposes the watermark video on the video content for playback and display.

Abstract: The present invention efficiently coordinates a plurality of blockchains. A settlement system, including: a service provider device 2 that transmits a template information transaction including a template of a transaction to a network 4 of a first blockchain; a user device that transmits a payment information transaction including a payment amount and an electronic signature which is generated by using the template of the transaction registered in the first blockchain; and a smart contract 41 included in the first blockchain, in which the smart contract 41 uses the payment amount and the template of the transaction to verify the electronic signature included in the payment information transaction, and the service provider device 2 uses the template of the transaction, the electronic signature, and the payment amount registered in the first blockchain to generate a settlement transaction and transmits the settlement transaction to a network 3 of a second blockchain.

Abstract: The purpose of the present invention is to enable managing contract data, which is to be registered in a distributed ledger, such that a part of the contract data is flexibly concealed without the need to install a centralized concealment server while freeing a user from complicated procedures or key management. Provided is a data registration method to be performed by a computer, comprising: a step for generating a common key for encrypting and decrypting an item included in data to be registered in a distributed ledger; a step for acquiring a public key for each of accounts of users having access authority to the item; a step for encrypting the common key with the public key for each of the accounts; and a step for registering the common key encrypted for each of the accounts in the distributed ledger via transactions.

Abstract: A right holder terminal 1 includes a registration unit that registers an identifier of a right holder in blockchain data registered with an identifier of a user, an electronic signature issuing unit that receives permission request data for content and transmits, to the user terminal, right holder electronic signature data generated by electronically signing a client random number issued by the user terminal by using a right holder secret key, a verification unit that receives user electronic signature data generated by electronically signing a server random number issued by the right holder terminal by using a user secret key and verifies that the user electronic signature data corresponds to the identifier of the user registered in the blockchain data, and a permission issuing unit that, if the user electronic signature data corresponds to the identifier of the user registered in the blockchain data, transmits the permission data.

Abstract: The present invention prevents falsification of ABI information and makes it possible for the users to safely read data on a blockchain. A registration terminal 1 includes an extraction unit 142 that extracts from a smart contract, ABI information used to access the smart contract and a transaction issuing unit 13 that issues a transaction including bytecode generated by compiling the smart contract and the ABI information, and an approval terminal 2 includes a verification unit 152 that verifies whether it is possible to access the bytecode included in the transaction by using the ABI information included in the transaction and a block generation unit 154 that, if it is possible to access the bytecode, generates a block including the transaction and makes the block and the ABI information reflected on a distributed ledger 11 of each terminal in the blockchain system.

Abstract: A consensus is formed for a private database shared within a group. A block verification device includes: a private database shared within a group; a communication unit receiving a list of transactions from an overall leader device; a transaction processing unit executing the transactions identified based on the list and outputting the execution results; and a block processing unit generating a proposal including a list, a digest of the private database after execution of the transactions, and a private dataset included in the transactions. The communication unit transmits the proposal to another block verification device belonging to the same group, and transmits the list, the digest of the private database, and the digest of the private dataset to all the other block verification devices when it is determined that a consensus for the proposal is formed.

Abstract: A key exchange system method safely conceal secret information recorded on a blockchain. A first terminal includes a license issuing unit that generates a first transaction including a first public key, a first key storage region that retains a first secret key, and a first encrypting and decrypting unit that generates a common key using deal-specific information, a second public key, and the first secret key, and a second terminal includes a license requesting unit that generates a second transaction including the second public key, a second key storage region that retains a second secret key, and a second encrypting and decrypting unit that generates the common key using deal-specific information, the first public key, and the second secret key. The first encrypting and decrypting unit encrypts secret information using the common key. The second encrypting and decrypting unit decrypts the encrypted secret information using the common key.