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EP-3996024-B1 - ELECTRONIC TRADING SYSTEM AND DATA CONCEALMENT METHOD FOR ELECTRONIC TRADING SYSTEM

EP3996024B1EP 3996024 B1EP3996024 B1EP 3996024B1EP-3996024-B1

Inventors

  • FUKUNAKA, Katsuhiro

Dates

Publication Date
20260506
Application Date
20210915

Claims (10)

  1. An electronic trading system in which a blockchain managing an electronic trading of a first trading target is managed by a plurality of nodes, wherein each of the plurality of nodes includes: a client unit configured to transmit an electronic trading request for a trading target; a smart contract management unit configured to automatically perform confirmation or fulfillment of contract conditions; a blockchain management unit configured to manage a distributed ledger of the blockchain; a first storage unit configured to store the distributed ledger of the blockchain; and a second storage unit configured to store content of the trading target to be concealed as actual data if the node is granted an access right to access the actual data of the trading target, wherein: the distributed ledger stored in the first storage unit is stored in all of the plurality of nodes managing the blockchain and is shared by all of the plurality of nodes; a first node among the plurality of nodes is configured to transmit the electronic trading request for a first trading target to a second node configured to manage the first trading target; the smart contract management unit of the second node is configured to, upon receipt of the electronic trading request by the second node, by referring to the first trading target, decide whether to grant to the first node an access right to access the actual data of the first trading target stored in the second storage unit of the second node and store the access right in the distributed ledger; and the first node is configured to store the actual data of the first trading target in the second storage unit of the first node if the access right is granted to the first node by the second node, with the actual data of the first trading target not being stored in the second storage units of the other nodes constituting the blockchain.
  2. The electronic trading system according to claim 1, wherein, when receiving an electronic trading request related to the first trading target from the client unit of a third node among the plurality of nodes, the smart contract management unit of the second node is configured to determine whether or not the first trading target is a product developed by a user of the second node, and in a case in which the first trading target is not the developed product, the smart contract management unit of the second node grants to the third node the access right to the actual data of the first trading target stored in the second storage unit of the second node.
  3. The electronic trading system according to claim 2, wherein, when receiving the electronic trading request related to the first trading target from the client unit of the third node, the smart contract management unit of the second node is configured to determine whether or not the first trading target is a product developed by the user of the second node, and in a case in which the first trading target is the developed product, the smart contract management unit of the second node further determines whether or not the first trading target includes an introduced product, and in a case in which the first trading target includes the introduced product, the smart contract management unit of the second node grants to a provider of the introduced product the access right to the actual data of the first trading target stored in the second storage unit of the second node.
  4. The electronic trading system according to claim 3, wherein, in a case in which the first trading target does not include the introduced product, the smart contract management unit of the second node is configured to store the actual data of the first trading target in the second storage unit of the second node.
  5. The electronic trading system according to claim 4, wherein the client unit of the third node is configured to transmit a request to refer to the actual data of the first trading target to the smart contract management unit of the third node, and the smart contract management unit of the third node is configured to determine whether or not the third node has the access right to the actual data of the first trading target, return information related to other nodes having the access right to the client unit of the third node in a case in which the third node has the access right, and return information indicating that the third node does not have the access right to the client unit of the third node in a case in which the third node does not have the access right.
  6. The electronic trading system according to claim 5, wherein the client unit of the third node is configured to transmit the request to refer to the actual data of the first trading target to the smart contract management units of other nodes having the access right, and the smart contract management units of other nodes having the access right are configured to determine whether or not the third node has the access right to the actual data of the first trading target, return an error to the third node in a case in which the third node does not have the access right, determine whether or not the actual data of the first trading target is stored in the second storage units of the host nodes in a case in which the third node has the access right, return the actual data of the first trading target to the third node in a case in which the actual data of the first trading target is stored, and return an error to the third node in a case in which the actual data of the first trading target is not stored.
  7. The electronic trading system according to claim 1, wherein the actual data of the first trading target is stored in a third-party organization in addition to the second storage units of the first node and the second node.
  8. A data concealment method for an electronic trading system in which a blockchain managing an electronic trading of a first trading target is managed by a plurality of nodes, wherein each of the plurality of nodes includes: a client unit configured to transmit an electronic trading request for a trading target; a smart contract management unit configured to automatically perform confirmation or fulfillment of contract conditions; a blockchain management unit configured to manage a distributed ledger of the blockchain; a first storage unit configured to store the distributed ledger of the blockchain; and a second storage unit configured to store content of the trading target to be concealed as actual data if the node is granted an access right to access the actual data of the trading target, wherein the distributed ledger stored in the first storage unit is stored in all of the plurality of nodes managing the blockchain and is shared by all of the plurality of nodes, the method comprising: transmitting, by a first node among the plurality of nodes, an electronic trading request for a first trading target to a second node configured to manage the first trading target; receiving, by the second node, the electronic trading request and deciding, by the smart contract management unit of the second node, by referring to the first trading target, whether to grant to the first node an access right to access the actual data of the first trading target stored in the second storage unit of the second node and store the access right in the distributed ledger; and storing, by the first node, the actual data of the first trading target in the second storage unit of the first node if the access right is granted to the first node by the second node, with the actual data of the first trading target not being stored in the second storage units of the other nodes constituting the blockchain.
  9. The data concealment method for an electronic trading system according to claim 8, wherein, when receiving an electronic trading request related to the first trading target from a third node among the plurality of nodes, the smart contract management unit of the second node determines whether or not the first trading target is a product developed by a user of the second node, in a case in which the first trading target is not the developed product, the smart contract management unit of the second node grants to the third node the access right to the actual data of the first trading target stored in the second storage unit of the second node, in a case in which the first trading target is the developed product, the smart contract management unit of the second node further determines whether or not the first trading target includes an introduced product, and in a case in which the first trading target includes the introduced product, the smart contract management unit of the second node grants to a provider of the introduced product the access right to the actual data of the first trading target stored in the second storage unit of the second node.
  10. The data concealment method for an electronic trading system according to claim 8, wherein, in a case in which the first trading target does not include the introduced product, the smart contract management unit of the second node stores the actual data of the first trading target in the second storage unit of the second node.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique that conceals a portion of electronic trading data shared by a large number of participants. 2. Description of the Related Art In recent years, a "blockchain" has been attracting attention as a technology to support Bitcoin. Trading data (history) is referred to as a "transaction". In the "blockchain", a group of a plurality of transactions is referred to as a "block", and the blocks are stored so as to be continuous. The "blockchain" has the feature that anyone can check all of the trading histories recorded on the blockchain, such as the buying and selling of Bitcoin, from a distributed ledger. That is, the blockchain has the feature that, since the fairness of trading is guaranteed by each node constituting the blockchain, the content of the trading is basically disclosed. Therefore, it is difficult to carry out trading and payment related to sensitive data desired to be concealed from a third party in the blockchain. For example, JP 2019-106639 A discloses a technique that guarantees the confidentiality of transactions and the fairness of trading in a blockchain. JP 2019-106639 A discloses an electronic trading device that constitutes a node of a blockchain related to the trading of electronic data. The electronic trading device includes: a receiving unit that receives a first transaction including electronic data encrypted by an encryption key in a terminal for transmitting the electronic data to be traded and a second transaction including the encryption key encrypted by a public key related to a terminal for receiving the electronic data; and a verification unit that, when receiving an electronic data verification request which is transmitted from the receiving terminal and includes a private key corresponding to the public key, decrypts the encryption key using the private key, decrypts the electronic data using the decrypted encryption key, and verifies the decrypted electronic data. As described above, in JP 2019-106639 A, the fairness of the trading is guaranteed without disclosing the content of the data traded by the encryption technology to all of the nodes constituting the blockchain. However, in JP 2019-106639 A, it is necessary to manage the correspondence relationship (combination) among the encryption key, the public key, and the private key for each transaction. When the number of transactions or trading participants increases, the number of combinations of the encryption keys, the public keys, and the private keys increases explosively, which makes it difficult to manage them. In other words, it is necessary to manage the correspondence relationship among the encryption key used by the transmitting terminal to encrypt the electronic data (trading data), the public key which is related to the receiving terminal and is used by the receiving terminal to encrypt the encryption key, and the private key which corresponds to the public key related to the receiving terminal and is transmitted from the receiving terminal for each transaction in order to ensure the confidentiality of trading. In addition, it is considered that the number of transactions increases as the number of trading participants increases. Therefore, it is considered that it becomes more difficult to manage the correspondence relationship among the encryption key, the public key, and the private key. Further, the trading data encrypted by the encryption key is transmitted as a transaction to the blockchain and is then stored in each node. Therefore, when a cryptanalysis technology is improved in the future, there is a concern that the content of the trading data will be seen by each node. US 2019/354967 A1 discloses a method and apparatus for management of a blockchain-based subject data, the method including creating subject data in accordance with a request of a user device; creating first metadata related to the subject data; creating a first block including the first metadata to store the first block in a blockchain included in the apparatus; creating first code information based on information included in the first block; and storing the first code information and the subject data in a database. US 2020/028688 A1 discloses a computing device associated with a first blockchain node which receives a transaction request along with related data for storage in an off-chain storage. SUMMARY OF THE INVENTION Accordingly, an object of the invention is to provide an electronic trading system and a data concealment method for an electronic trading system that can manage the confidentiality of trading data using a blockchain with a small amount of information. In addition, another object of the invention is to provide an electronic trading system and a data concealment method for an electronic trading system that can reduce a storage capacity for storing transactions without concern that the trading data will be decrypted. In order t