Settlement system, settlement method, user device, and settlement program

A settlement method in which a first blockchain and a second blockchain are cooperated, the settlement method comprising:

• transmitting, by a service provider device, a template information transaction that includes a template of a transaction to a network of the first blockchain;
• generating, by a user device, an electronic signature by using the template of the transaction registered in the first blockchain;
• and
• transmitting, by the user device, a payment information transaction that includes the electronic signature and a payment amount to the network of the first blockchain,
• wherein a smart contract included in the first blockchain verifies the electronic signature included in the payment information transaction by using the payment amount and the template of the transaction,
• wherein the service provider device generates (i) a settlement transaction by using the template of the transaction registered in the first blockchain, the electronic signature, and the payment amount and (ii) a pre-image at time of generating the template of the transaction, sets a hash of the pre-image, and transmits the settlement transaction to a network of the second blockchain to thereby cause (i) generation of a block including the settlement transaction and (ii) the block to be reflected to terminals connected to second blockchain through loose synchronization among the terminals,
• wherein 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, and
• wherein the plurality of output conditions include a first condition including a time lock by which the settlement transaction becomes usable after an elapse of a second time period and a second condition indicating that the settlement transaction becomes usable based on the hash of the pre-image and the electronic signature of the user device being submitted by the user device,
• wherein the user device:
• transmits a cancellation request of the payment information transaction to the service provider device, and
• transmits, to the network of the first blockchain, another payment information transaction for cancellation that includes another electronic signature generated by the service provider device by using a template of another transaction registered in the first blockchain and another payment amount,
• wherein the service provider device:
• transmits another template information transaction that includes the template of the another transaction to the network of the first blockchain, and
• based on the another payment information transaction registered in the first blockchain being consented within the second time period, transmits, to the network of the first blockchain, a pre-image transaction that includes the pre-image of the hash specified in a hash lock included in the plurality of output conditions, and
• wherein:
• the user device transmits a penalty transaction to the network of the second blockchain using the pre-image transaction, and
• based on the penalty transaction being received within the second time period, the settlement transaction is funded to the user device.

A user device in a settlement system in which a first blockchain and a second blockchain are cooperated, the user device comprising:

• a funding transaction generating unit that transmits, to a network of the second blockchain, a funding transaction for funding a predetermined amount of deposit;
• and
• a payment transaction generation unit generates an electronic signature by using a template of the transaction registered in the first blockchain by a service provider device and transmits a payment information transaction that includes an electronic signature and a payment amount to a network of the first blockchain to thereby cause (i) generation of a block including a settlement transaction and (ii) the block to be reflected to terminals connected to second blockchain through loose synchronization among the terminals,
• wherein a plurality of output conditions are set to the template of the transaction, and a settlement transaction generated by the service provider device by using the template of the transaction, the electronic signature, and the payment amount becomes usable when any one of the plurality of output conditions is satisfied, and
• wherein the plurality of output conditions include a first condition including a time lock by which the settlement transaction becomes usable after an elapse of a second time period and a second condition indicating that the settlement transaction becomes usable based on a hash of a pre-image and the electronic signature of the user device being submitted by the user device, the pre-image to which the hash is set and being generated by the service provider device at time of generating the template of the transaction,
• wherein the user device:
• transmits a cancellation request of the payment information transaction to the service provider device, and
• transmits, to the network of the first blockchain, another payment information transaction for cancellation that includes another electronic signature generated by the service provider device by using a template of another transaction registered in the first blockchain and another payment amount,
• wherein:
• the user device transmits a penalty transaction to the network of the second blockchain using a pre-image transaction that includes the pre-image of the hash specified in a hash lock included in the plurality of output conditions, and
• based on the penalty transaction being received within the second time period, the settlement transaction is funded to the user device.