Transaction system and transaction method

Abstract

To perform transaction guarantee between a block chain for NFT and a block chain for settlement with a combination of both block chains made dynamically settable.SOLUTION: A cross chain escrow 5 for performing transaction guarantee about NFT transfer and settlement of a cryptographic asset is provided, the cross chain escrow 5 receives an exhibition request for NFT to a market 4 from an exhibitor 2, the NFT is deposited to an escrow operator in a block chain for NFT 6, a purchase request for NFT is received from a purchaser 3, a cryptographic asset corresponding to a counter value of NFT is deposited to the escrow operator on a block chain for settlement 7, the deposited NFT is transferred to the purchaser 3 on the block chain for NFT 6, and the deposited cryptographic asset is transferred to the exhibitor 2 on the block chain for settlement 7.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a technology for transactions on a blockchain, and in particular to a technology that is effective when applied to a trading system and trading method for settling NFT (Non-Fungible Token) transactions with crypto assets. [Background technology]

[0002] In online marketplace transactions for NFTs that use blockchain, such as OpenSea (registered trademark, the same below), transactions are guaranteed only within a single blockchain. In this case, settlement is made with the native cryptocurrency (virtual currency) of the blockchain on which the NFT is being traded, for example, ETH if the target blockchain is Ethereum (registered trademark, the same below), PolygonETH and Matic if the target blockchain is Polygon.

[0003] Therefore, buyers are burdened with having to prepare crypto assets to purchase the NFTs they are trading for. In addition, sellers of NFTs are also required to receive payment in crypto assets corresponding to the blockchain on which they are selling. This means that, for example, when a buyer selects a blockchain to sell NFTs on based on various conditions such as the volume of transactions, the specialty of the NFTs they handle, or the level of so-called "gas fees," they are unable to meet the needs of buyers who wish to make payments in crypto assets that are compatible with a different blockchain, such as a crypto asset that they regularly use or a crypto asset with a large amount of coins in circulation.

[0004] In response to the above-mentioned constraints due to the fact that NFT transfers and payments with crypto assets are processed on the same blockchain, for example, Patent Gazette No. 7169420 (Patent Document 1) describes an information processing device operated by an operating company that manages tokens, which comprises an acceptance means for accepting payment instructions by transferring coins (crypto assets) associated with cash currency, and a transmission means for transmitting a transfer instruction for the tokens associated with the coins in response to the payment instruction to an electronic currency management system, and the electronic currency management system comprises a coin blockchain that manages the coins, a token blockchain that manages the tokens, and a transfer means for transferring coins associated with the tokens in the coin blockchain in response to the transfer of the token in the token blockchain. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7169420 Summary of the Invention [Problem to be solved by the invention]

[0006] According to the conventional technology described in Patent Document 1, a blockchain for NFTs (tokens) and a blockchain for settlement with crypto assets are separate blockchains, and it is possible to synchronize and link the transfer of NFTs and the transfer of crypto assets between them. In other words, it is possible to settle the consideration without using the native crypto assets in the blockchain where the NFT to be traded exists.

[0007] However, the combination of the blockchain for NFTs and the blockchain for payments is preset and fixed, and it is not possible to transfer NFTs and settle crypto assets in any combination according to user needs, etc.

[0008] Therefore, the object of the present invention is to provide a trading system and trading method that allows the combination of a blockchain for NFTs and a blockchain for payment to be dynamically configured and guarantees transactions between the two.

[0009] The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0010] Among the inventions disclosed in this application, a brief summary of representative inventions is as follows.

[0011] A trading system that is a representative embodiment of the present invention is a trading system that transfers an NFT from a seller to a buyer on a blockchain in an online market and settles the consideration with crypto assets, and has an escrow processing unit that guarantees the transaction for the transfer of the NFT and the settlement of the crypto assets. The escrow processing unit, upon receiving a request from the seller to list the NFT on the online market, deposits the NFT with a specified person on a first blockchain where the NFT is located, and upon receiving a request from the buyer to purchase the NFT, deposits the crypto assets equivalent to the consideration for the NFT with the specified person on a second blockchain where the crypto assets are located, transfers the NFT deposited on the first blockchain to the buyer, and transfers the crypto assets deposited on the second blockchain to the seller.

[0012] The present invention can also be applied to a method executed in such a trading system. Effect of the Invention

[0013] The effects obtained by the representative inventions disclosed in this application can be briefly explained as follows.

[0014] In other words, according to a representative embodiment of the present invention, it is possible to dynamically set up a combination of a blockchain for NFTs and a blockchain for payment, and to guarantee transactions between the two. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram showing an overview of an example of the configuration of a trading system according to an embodiment of the present invention. [Diagram 2] 13(a) to 13(c) are diagrams outlining example configurations of a blockchain for transferring NFTs and a blockchain for transferring crypto assets. [Diagram 3] FIG. 2 is a diagram showing an overview of how each part cooperates in an escrow format in one embodiment of the present invention. [Figure 4] A diagram outlining an example of the processing flow when listing an NFT in one embodiment of the present invention. [Diagram 5] A diagram outlining an example of the processing flow when preparing to purchase an NFT in one embodiment of the present invention. [Figure 6] FIG. 1 is a diagram outlining an example of the processing flow when purchasing an NFT in one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiment, the same parts are generally given the same reference numerals, and the repeated explanations will be omitted. On the other hand, a part that has been described with a reference numeral in a certain drawing may be referred to with the same reference numeral in the explanation of another drawing, although it will not be shown again.

[0017] <Summary> The trading system, which is one embodiment of the present invention, is an information processing system that realizes an online marketplace for NFTs using blockchain, and is configured to guarantee transactions in an escrow format between the blockchain for the transfer of NFTs to be put up for sale and the blockchain for the transfer of crypto assets (coins) used to settle the consideration.

[0018] This makes it possible to dynamically set the combination of blockchains for NFTs and blockchains for payments according to user needs, enabling transaction guarantees for the transfer of NFTs and crypto assets on different blockchains.

[0019] <System configuration> 1 is a diagram showing an overview of an example of the configuration of a trading system according to an embodiment of the present invention. The trading system 1 includes, for example, a market 4, which is an online marketplace that provides NFT trading services to NFT sellers 2 and buyers 3, an NFT blockchain 6 that performs processing related to the transfer of NFTs, and a payment blockchain 7 that performs processing related to the transfer of crypto assets. This embodiment further includes a cross-chain escrow 5, which is a subsystem that guarantees transactions in an escrow format between the NFT blockchain 6 and the payment blockchain 7.

[0020] The market 4 can use a publicly available NFT marketplace service such as OpenSea, so long as it has a configuration, function, interface, etc. that can incorporate or link with the cross-chain escrow 5 subsystem. It is also possible to implement and build a new marketplace service and use it. In addition, the seller 2 and the buyer 3 access the market 4 via a network such as the Internet (not shown) using a seller terminal 21 and a buyer terminal 31, which are information processing terminals such as PCs and smartphones, respectively, and use the marketplace service using a web browser, dedicated application, etc. (not shown).

[0021] The cross-chain escrow 5 is a device (escrow processing unit) that is configured, for example, by a server device, a virtual server constructed on a cloud computing service, a PC, etc., and that realizes various functions related to transaction guarantee in an escrow format between the NFT blockchain 6 and the settlement blockchain 7 by executing an OS (Operating System), a DBMS (DataBase Management System), middleware such as a web server program, and software running thereon, which are expanded on memory from a recording device such as an HDD (Hard Disk Drive) or SSD (Solid State Drive) by a CPU (Central Processing Unit) not shown.

[0022] This cross-chain escrow 5 has various parts, such as an auction acceptance unit 51, a purchase acceptance unit 52, and a transaction assurance unit 53, which are implemented as software, for example.

[0023] The listing reception unit 51 has the function of accepting requests to list NFTs from the seller 2 (seller terminal 21) via the market 4, and performing processing related to the connection between the seller 2, the market 4, and the NFT blockchain 6 when listing NFTs, such as depositing the NFT to be listed on the NFT blockchain 6 with an escrow operator (an operator that operates the cross-chain escrow 5).

[0024] The purchase reception unit 52 has the function of accepting requests to purchase NFTs from the purchaser 3 (purchaser terminal 31) via the market 4 and performing processing related to the connection between the purchaser 3, the market 4, and the payment blockchain 7 when purchasing NFTs, such as depositing crypto assets to pay the price with an escrow operator.

[0025] The escrow guarantee section 53 has a function of providing transaction guarantee in an escrow format that coordinates the transfer process of NFTs held by the escrow operator to the NFT purchaser 3 on the NFT blockchain 6 and the transfer process of cryptocurrency (coins) held by the escrow operator to the seller 2 on the payment blockchain 7.

[0026] The NFT blockchain 6 and the payment blockchain 7 can each appropriately use multiple types of generally available commercial services, etc., as long as they are blockchain services that the market 4 can support. Note that the expressions "for NFT" and "for payment" are expressions from the perspective of the functions assumed in this embodiment, and it is not necessarily a dedicated blockchain specialized for such functions. It goes without saying that a blockchain that functions as the NFT blockchain 6 in a certain transaction may function as the payment blockchain 7 in another transaction, or vice versa.

[0027] <Separation of the NFT Blockchain and the Payment Blockchain> FIG. 2 is a diagram showing an overview of a configuration example of a blockchain for NFT transfer and a blockchain for cryptocurrency transfer. FIG. 2(a) is a configuration example in the prior art, FIG. 2(b) is a configuration example when using the technology described in Patent Document 1, and FIG. 2(c) is a configuration example in the transaction system 1 of this embodiment. Each shows an overview of the case where the seller 2 and the purchaser 3 each access the market 4 and conduct NFT trading and payment with cryptocurrency on the blockchain.

[0028] The example in Figure 2(a) shows that the transfer of the NFT and the transfer of the cryptocurrency take place on the same blockchain. As shown in the diagram on the left, if seller 2 puts up an NFT on blockchain 8a, buyer 3 will also prepare cryptocurrency on the same blockchain 8a to make payment. On the other hand, as shown in the diagram on the right, if seller 2 puts up an NFT on another blockchain 8b, buyer 3 will also prepare cryptocurrency on the same blockchain 8b to make payment. In this way, buyer 3 needs to prepare cryptocurrency that is native to the blockchain on which seller 2 put up the NFT.

[0029] The example of FIG. 2(b) shows that the transfer of NFTs and the transfer of crypto assets can be performed on different blockchains. As shown in the diagram on the left, when the seller 2 puts up an NFT on the NFT blockchain 6a, the buyer 3 can make payment with crypto assets on a different payment blockchain 7a. However, as shown in the diagram on the right, when the seller 2 puts up an NFT on another NFT blockchain 6b, the buyer 3 needs to prepare crypto assets on yet another payment blockchain 7b to make payment. In other words, although the NFT blockchain 6 and the payment blockchain 7 can be separated, the combination is preset and fixed, and the buyer 3 still needs to prepare crypto assets corresponding to the payment blockchain 7 that is combined with the NFT blockchain 6 on which the seller 2 put up the NFT.

[0030] On the other hand, the example of FIG. 2(c) shows that the transfer of NFTs and crypto assets can be carried out on different blockchains, and the combination of these can be changed as desired. As shown in the diagram on the left, if the seller 2 puts up an NFT on the NFT blockchain 6a, the buyer 3 can make payment with crypto assets on a different payment blockchain 7a, as in the example of FIG. 2(b). On the other hand, as shown in the diagram on the right, even if the seller 2 puts up an NFT on a different NFT blockchain 6b, the buyer 3 can make payment with crypto assets held on the same payment blockchain 7a as in the diagram on the left.

[0031] This allows, for example, seller 2 to select an NFT blockchain 6 based on various conditions such as the volume of transactions, the specialty of the NFTs handled, and the level of "gas fees," while purchaser 3 can independently select a payment blockchain 7 that corresponds to the desired cryptocurrency, such as a cryptocurrency that the purchaser uses frequently or a cryptocurrency with a large circulation, and use that to make payment.

[0032] <Image of collaboration> FIG. 3 is a diagram showing an overview of the cooperation image of each part in an escrow format in one embodiment of the present invention. First, (1) the seller 2 exhibits an NFT via the market 4 (deposits the NFT to an escrow business operator on the NFT blockchain 6) and cooperates with the market 4 and the cross-chain escrow 5 with an address on the settlement blockchain 7 for receiving the cryptocurrency as a consideration. (2) The purchaser 3 requests the purchase of an NFT via the market 4 and deposits the cryptocurrency (coins) as a consideration with the escrow business operator on the settlement blockchain 7. (3) The market 4 and the cross-chain escrow 5 transfer the NFT to the purchaser 3 on the NFT blockchain 6, and as a result, (4) the purchaser 3 receives the NFT. Then, (5) the market 4 and the cross-chain escrow 5 transfer the cryptocurrency to the seller 2 on the settlement blockchain 7, and as a result, (6) the seller 2 receives the cryptocurrency as a consideration.

[0033] In this way, the purchaser 3 deposits crypto assets with an escrow operator on the payment blockchain 7, and once the transfer of the NFT has been made on the NFT blockchain 6, the crypto assets on the payment blockchain 7 are sent to the seller 2, and this escrow-style transaction processing is controlled and realized by the cross-chain escrow 5. This makes it possible to avoid complex processing such as rolling back the transfer of the NFT in the event of a payment failure, while guaranteeing the transaction for the transfer of the NFT and the transfer of the crypto assets in return.

[0034] <Processing flow> 4 is a diagram outlining an example of the flow of processing when listing an NFT in one embodiment of the present invention. First, the seller 2 (seller terminal 21) requests, via his / her wallet 22 (which may be an application on the seller terminal 21 or a service on the Internet), the payment blockchain 7 corresponding to the crypto asset to be received as payment for the NFT to issue an address to which the crypto asset will be paid (S01, S02), and the payment blockchain 7 issues the address (S03). The issued address is recorded in the wallet 22 of the seller 2.

[0035] In addition, it is desirable to receive addresses from the payment blockchain 7 for multiple types of crypto-assets (payment blockchain 7) that are expected to be used for payment by the purchaser 3, so as to broaden the options of crypto-assets to be used for payment of the consideration. If an address to which the consideration is paid has already been issued from the target payment blockchain 7, this can be used continuously, and therefore the above steps S01 to S03 are not necessary.

[0036] Thereafter, the seller 2 (seller terminal 2) accesses the market 4 and requests to put up the NFT (S04). This putting up request includes address information acquired by the above processes of S01 to S03 as the address of the payment destination of the consideration when the target NFT is purchased. The market 4 that receives the putting up request requests the cross-chain escrow 5 to put up the item (S05). The putting up acceptance unit 51 of the cross-chain escrow 5 requests confirmation and permission from the seller 2 for the putting up via the wallet 22 of the seller 2 (S06, S07). This request also includes information on the address of the escrow operator in the blockchain 6 for NFTs to which the item will be put up, and an instruction to deposit the NFT with the escrow operator.

[0037] The seller 2, who has been asked to confirm and approve the listing, performs consent processing (digital signature) in the wallet 22 and approves the listing (S08). In response to this, the wallet 22 deposits the NFT to the address of the escrow operator in the NFT blockchain 6 based on the above instructions from the cross-chain escrow 5 (S09, S10). Although it is expressed as "depositing," specifically, in the case of Ethereum, for example, the wallet 22 performs processing (approve) to grant the authority to transfer the NFT to the escrow operator in the NFT blockchain 6.

[0038] The wallet 22 notifies the cross-chain escrow 5 that the NFT has been deposited (S11). This notification also includes the address of the NFT on the NFT blockchain 6, the address of the payment destination of the cryptocurrency to the seller 2 on the payment blockchain 7, and the signature of the seller 2 granting permission to sell the cryptocurrency.

[0039] Having received the notification, the listing acceptance unit 51 of the cross-chain escrow 5 requests the NFT blockchain 6 to confirm whether the NFT deposit (approve transaction) in step S10 was completed normally (S12), and the NFT blockchain 6 responds with the transaction processing result (S13). Since the approve transaction is an asynchronous process, it is necessary to check the processing result separately. If the approve transaction is being processed, it will wait for a certain period of time and then check again. If the transaction ended abnormally, the listing process will end. If it ended normally, the market 4 will be notified that the listing has been completed (S14), and the market 4 will carry out listing completion processing, such as notifying the seller 2 (seller terminal 21) by displaying the screen (S15).

[0040] 5 is a diagram outlining an example of a process flow when preparing to purchase an NFT in one embodiment of the present invention. The purchaser 3 (purchaser terminal 31) requests, via his / her wallet 32, the issuance of an address from the payment blockchain 7 corresponding to the crypto asset to be used for payment of the consideration for the NFT purchase (the crypto asset selected by the purchaser 3 from among the crypto assets that the seller 2 of the target NFT has decided to use for payment of the consideration in steps S01 to S03 of FIG. 4 described above) (S21, S22), and the payment blockchain 7 issues an address (S23). The issued address is recorded in the wallet 32 ​​of the purchaser 3.

[0041] Thereafter, the purchaser 3 requests the purchase of crypto assets (coins) to pay for the NFT purchase through a predetermined procedure such as via the wallet 32 ​​at any time (S24, S25), and deposits the purchased crypto assets in the address issued in step S23 in the settlement blockchain 7. For example, the purchaser deposits crypto assets purchased from a crypto asset (virtual currency) exchange business such as Coincheck (registered trademark) by transferring the crypto assets to his / her own address. Note that the process contents of steps S24 and S25 related to the purchase of crypto assets may differ depending on the target crypto assets, and therefore the purchase will actually be made through a predetermined procedure corresponding to each target crypto asset.

[0042] FIG. 6 is a diagram outlining an example of a process flow when purchasing an NFT in one embodiment of the present invention. First, the purchaser 3 (purchaser terminal 31) accesses the market 4 and requests the purchase of an NFT (S31). The market 4 that receives the purchase request requests the cross-chain escrow 5 to make a purchase (S32). The purchase acceptance unit 52 of the cross-chain escrow 5 requests the purchaser 3's confirmation and permission for the purchase via the purchaser 3's wallet 32 ​​(S33, S34). This request also includes information on the address of the escrow operator in the settlement blockchain 7 related to the cryptocurrency used by the purchaser 3 for payment, and an instruction to deposit the cryptocurrency with the escrow operator.

[0043] The purchaser 3, who is asked to confirm and approve the purchase, performs consent processing (electronic signature) in the wallet 32 ​​and approves the purchase (S35). In response to this, the wallet 32 ​​deposits crypto assets (coins) in the amount equivalent to the payment to the address of the escrow operator in the settlement blockchain 7 based on the above instruction from the cross-chain escrow 5 (S36, S37). Specifically, the wallet 32 ​​performs processing (transfer) for the settlement blockchain 7 to transfer the crypto assets in the amount equivalent to the payment to the escrow operator.

[0044] The wallet 32 ​​notifies the cross-chain escrow 5 that the cryptocurrency has been deposited (S38). This notification also includes the address for receiving the NFT of the purchaser 3 on the NFT blockchain 6, the sender address of the purchaser 3 on the settlement blockchain 7 (the address of the deposited cryptocurrency), and the signature of the purchase permission by the purchaser 3.

[0045] Upon receiving the notification, the purchase acceptance unit 52 of the cross-chain escrow 5 requests the payment blockchain 7 to confirm whether the deposit of the cryptocurrency (transfer transaction) in step S37 was completed normally (S39), and the payment blockchain 7 responds with the transaction processing result (S40). Since the transfer transaction is also an asynchronous process, it is necessary to check the processing result separately. If the transfer transaction is being processed, it will wait for a certain period of time and then check again. If the transaction ended abnormally, the purchase process will be terminated.

[0046] If the transaction has been completed successfully, the transaction assurance unit 53 of the cross-chain escrow 5 requests the NFT blockchain 6 to transfer the target NFT from the seller 2 to the buyer 3 (S41), and the NFT blockchain 6 transfers the NFT (S42). After that, the transaction assurance unit 53 of the cross-chain escrow 5 requests the NFT blockchain 6 to confirm whether the NFT transfer (transfer transaction) has been completed successfully (S42), and the NFT blockchain 6 responds with the transaction processing result (S44). If the transaction related to the transfer of the NFT is abnormally terminated, the purchase process is terminated. At this time, the crypto assets deposited in the address of the escrow company in the settlement blockchain 7 may be returned to the wallet 32 ​​of the purchaser 3, in response to instructions from the transaction assurance unit 53 or the escrow company.

[0047] If the transfer of the NFT has been completed successfully, the only thing that remains to be done is to make a separate payment. Therefore, as shown in the figure, the transaction assurance unit 53 of the cross-chain escrow 5 notifies the market 4 of the purchase completion at this stage (S45), and the market 4 may perform a process of completing the purchase by notifying the purchaser 3 (purchaser terminal 31) by displaying a screen (S46). Meanwhile, in parallel with this, the transaction assurance unit 53 of the cross-chain escrow 5 requests the payment blockchain 7 to transfer (remit) crypto assets (coins) in an amount equivalent to the payment from the purchaser 3 to the seller 2 (S47), and the payment blockchain 7 transfers the crypto assets to make a payment (S48). At this time, the cross-chain escrow 5 may collect crypto assets equivalent to a transaction fee from the seller 2 and / or the purchaser 3.

[0048] As described above, according to the trading system 1 which is one embodiment of the present invention, by setting up a cross-chain escrow 5 for the market 4, it is possible to guarantee transactions in an escrow format between the NFT blockchain 6 where NFTs are listed and the payment blockchain 7 where payment is made in crypto assets.

[0049] This makes it possible to dynamically set the combination of the NFT blockchain 6 and the payment blockchain 7 according to the needs of the seller 2 and the buyer 3, and to realize transaction guarantees for the transfer of NFTs and crypto assets on different blockchains. In other words, the seller 2 selects the NFT blockchain 6 based on various conditions and puts up an NFT, while the buyer 3 can independently select the payment blockchain 7 corresponding to the crypto asset they desire and make payment.

[0050] The invention made by the present inventor has been specifically described above based on the embodiment, but it goes without saying that the present invention is not limited to the above embodiment and can be modified in various ways without departing from the gist of the invention. Furthermore, the above embodiment has been described in detail to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to having all of the configurations described. Furthermore, it is possible to add, delete, or replace part of the configuration of the above embodiment with other configurations.

[0051] In addition, the above-mentioned configurations, functions, processing units, processing means, etc. may be realized in part or in whole by hardware, for example, by designing them as integrated circuits. In addition, the above-mentioned configurations, functions, etc. may be realized in software by a processor interpreting and executing a program that realizes each function. Information such as the program, table, file, etc. that realizes each function can be stored in a recording device such as a memory, a hard disk, or an SSD, or in a recording medium such as an IC card, an SD card, or a DVD.

[0052] In addition, in each of the above figures, the control lines and information lines are shown as those considered necessary for explanation, and do not necessarily show all the control lines and information lines in the actual implementation. In reality, it can be considered that almost all the components are connected to each other. [Industrial Applicability]

[0053] The present invention can be used in a trading system and trading method for settling NFT transactions with crypto assets. [Explanation of symbols]

[0054] 1... Trading system, 2... Seller, 3... Buyer, 4... Market, 5... Cross-chain escrow, 6... Blockchain for NFT, 7... Blockchain for payment, 8... Blockchain, 21... seller terminal, 31... buyer terminal, 51…Production reception department, 52…Purchase reception department, 53…Transaction assurance department

Claims

1. A trading system that transfers Non-Fungible Tokens (NFTs) from sellers to buyers on a blockchain in an online market and settles the payment in crypto assets, An escrow processing unit that performs transaction guarantee for the transfer of the NFT and the settlement of the crypto asset, The escrow processing unit: Upon receiving a request from the seller to put the NFT on the online market, depositing the NFT with a predetermined person in a first blockchain where the NFT is located; A trading system that, upon receiving a purchase request for the NFT from the purchaser, deposits the crypto asset equivalent to the value of the NFT with the specified person on the second blockchain where the crypto asset is located, transfers the NFT deposited on the first blockchain to the purchaser, and transfers the crypto asset deposited on the second blockchain to the seller.

2. 2. The trading system according to claim 1, The escrow processing unit: When depositing the NFT in the first blockchain to the specified person, instruct the seller to deposit the NFT by providing the address of the specified person in the first blockchain to the seller's first wallet; A trading system that obtains from the first wallet the address of the NFT deposited in the first blockchain and the address of the seller in the second blockchain.

3. 2. The trading system according to claim 1, The escrow processing unit: When depositing the crypto asset in the second blockchain to the specified person, the address of the specified person in the second blockchain is provided to the second wallet of the purchaser to instruct the deposit; A trading system that obtains from the second wallet the address of the purchaser in the first blockchain and the address of the deposited cryptocurrency in the second blockchain.

4. A transaction method in a transaction system for transferring Non-Fungible Tokens (NFTs) from sellers to buyers on a blockchain in an online market and settling the payment in crypto assets, comprising: The transaction system has an escrow processing unit that performs transaction guarantee for the transfer of the NFT and the settlement of the crypto asset, The escrow processing unit: receiving a request from the seller to put the NFT on the online market, depositing the NFT with a predetermined person in a first blockchain where the NFT is located; receiving a purchase request for the NFT from the purchaser, depositing the crypto asset equivalent to the value of the NFT to the specified person on a second blockchain where the crypto asset is located; transferring the NFT deposited on the first blockchain to the purchaser; A trading method comprising the steps of: transferring the crypto asset deposited on the second blockchain to the seller.

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