Server device, trading system, trading method, and program

Abstract

The present invention involves: a generation unit that, on the basis of details of content to be traded, generates first information of the content that does not have color information, and second information corresponding to the color information; a first response unit that transmits the first information and a registration request to request registration of a viewing terminal device for viewing the content to a terminal device of a purchaser who has completed a procedure for purchasing the content, and stores, in a storage unit, identification information of the viewing terminal device notified of in response to the registration request; and a second response unit that, upon receiving a transmission request to request transmission of the second information, determines whether or not the terminal device identification information included in the transmission request matches the identification information of the viewing terminal device stored in the storage unit, and transmits the second information to the viewing terminal device when it is determined that the terminal device identification information included in the transmission request matches the identification information of the viewing terminal device stored in the storage unit.

Description

Server device, trading system, trading method, and program

[0001] The present invention relates to a server device, a trading system, a trading method, and a program.

[0002] There is non-fungible token (NFT) art (see, for example, Patent Document 1). NFT art is digital content that can verify its uniqueness and ownership by embedding individual information (tokens) using blockchain. Marketplaces that handle NFT art (NFT marketplaces) allow transactions to be made to buy and sell NFT art.

[0003] Patent No. 7058898

[0004] However, while the use of blockchain can prevent transaction tampering in NFT marketplaces, it has been difficult to prevent third parties from duplicating NFT art. The technology described in Patent Literature 1 does not disclose how to prevent data duplication of NFT art. For example, it is possible for a third party to duplicate original NFT art and put it up for sale. For this reason, a mechanism that makes it difficult to duplicate NFT art has been sought.

[0005] In view of the above-mentioned problems, the present invention aims to make it difficult to reproduce NFT art.

[0006] One aspect of the present invention is a server device comprising: a generation unit that generates first information that does not have color information of the content and second information that corresponds to the color information based on the content of the content that is the subject of a transaction; a first response unit that sends the first information and a registration request requesting registration of a viewing terminal device for viewing the content to a terminal device of a purchaser who has completed the purchase procedure for the content, and stores in a memory unit the identification information of the viewing terminal device notified in response to the registration request; and a second response unit that, when receiving a transmission request requesting the transmission of the second information, determines whether the identification information of the terminal device included in the transmission request matches the identification information of the viewing terminal device stored in the memory unit, and sends the second information to the viewing terminal device when it is determined that they match.

[0007] Another aspect of the present invention is a trading system including the server device described above and the viewing device.

[0008] Another aspect of the present invention is a transaction method performed by a server device that is a computer, in which an acquisition unit generates first information that does not have color information of the content and second information that corresponds to the color information based on the content of the content that is the subject of the transaction, a first response unit transmits the first information and a registration request to the terminal device of the purchaser who has completed the purchase procedure for the content, requesting registration of a viewing terminal device for viewing the content, and stores in a memory unit the identification information of the viewing terminal device notified in response to the registration request, and when a second response unit receives a transmission request requesting the transmission of the second information, determines whether the identification information of the terminal device included in the transmission request matches the identification information of the viewing terminal device stored in the memory unit, and if it determines that they match, transmits the second information to the viewing terminal device.

[0009] Another aspect of the present invention is a program that causes a server device, which is a computer, to generate first information that does not have color information of the content and second information that corresponds to the color information based on the content of the content that is the subject of a transaction, transmits the first information and a registration request to a terminal device of a purchaser who has completed the purchase procedure for the content, requesting registration of a viewing terminal device for viewing the content, stores identification information of the viewing terminal device notified in response to the registration request in a memory unit, and, when a transmission request requesting transmission of the second information is received, determines whether the identification information of the terminal device included in the transmission request matches the identification information of the viewing terminal device stored in the memory unit, and, when it is determined that they match, transmits the second information to the viewing terminal device.

[0010] The present invention makes NFT art difficult to copy.

[0011] FIG. 1 is a block diagram illustrating the configuration of a trading system in an embodiment. FIG. 2 is a block diagram illustrating the configuration of a server device in an embodiment. FIG. 3 is a diagram illustrating an example of distribution management information in an embodiment. FIG. 4 is a sequence diagram illustrating the flow of processing performed by a trading system in an embodiment. FIG. 5 is a sequence diagram illustrating the flow of processing performed by a trading system in an embodiment. FIG. 6 is a diagram illustrating the basic configuration of a trading system in an embodiment. FIG. 7 is a sequence diagram illustrating the flow of processing performed by a conventional trading system.

[0012] An embodiment of the present invention will be described below. FIG. 1 is a block diagram illustrating the configuration of a trading system according to the embodiment. The trading system 1 includes an NFT marketplace 10 and multiple user terminals. These multiple user terminals are terminal devices operated by each of multiple users who use the NFT marketplace 10, such as smartphones, personal computers (PCs), and tablet terminals. In this diagram, the multiple user terminals are shown as an original copyright holder terminal 50, a buyer 1 terminal 70, a buyer 1 display 71, and a buyer 2 terminal 80. The buyer 1 terminal 70 is a terminal device operated by buyer 1, who purchases NFT art. The buyer 1 display 71 is a display terminal that displays the NFT art purchased by buyer 1. The buyer 1 terminal 70 and the buyer 1 display 71 may be the same device or different devices. The buyer 2 terminal 80 is a terminal device operated by a buyer (buyer 2) different from buyer 1.

[0013] In the trading system 1, the NFT marketplace 10 and each of the user terminals are communicatively connected. The means of communication between the NFT marketplace 10 and each of the user terminals is not limited to a specific means, and may be any means that allows communication, such as the Internet, a wired LAN, a wireless LAN, or a combination thereof.

[0014] The NFT Marketplace 10 is a marketplace that deals in NFT art. NFT art is digital content associated with an NFT. The digital content here includes still images and moving images containing two-dimensional or three-dimensional objects, such as digital paintings, illustrations, animations, trading cards, and game items. The NFT Marketplace 10 uses a blockchain to manage attribute information, such as the owner, of digital content associated with an NFT (non-fungible token). By using a blockchain to manage attribute information of digital content associated with an NFT, the uniqueness and owner of the digital content associated with the NFT can be verified. Users can purchase and sell NFT art using the NFT Marketplace 10.

[0015] The NFT marketplace 10 has functions related to trading of NFT art, such as issuing, purchasing, and selling NFTs. For example, the NFT marketplace 10 issues NFTs in response to requests for issuing NFTs, sells or buys NFTs in response to requests for purchasing or selling NFTs, and settles the price of NFTs.

[0016] 7 is a sequence diagram illustrating the flow of processing performed by a conventional trading system. The original copyright holder terminal 50 requests the server device 200, which handles transactions in a conventional NFT marketplace, to issue an NFT corresponding to digital content created by the original author, thereby carrying out the listing procedure (step S1). The server device 200, for example, executes information processing in response to the NFT issuance request from the original author of the digital content (step 2). As information processing in response to the NFT issuance request, the server device 200 issues an NFT associated with the digital content requested by the original author, and records information about the original author who requested the NFT issuance on the blockchain as information about the holder of the issued NFT.

[0017] Once an NFT is issued and attribute information such as its owner is recorded on the blockchain, users can view the digital content corresponding to the NFT in the NFT marketplace. In this way, digital content is distributed in the market as an object of sale and purchase. After executing information processing in response to the NFT issuance request, the server device 200 transmits a registration completion notice indicating that the listing registration has been completed to the original copyright holder terminal 50 (step S3). Meanwhile, the buyer 1 terminal 70 performs the purchase procedure by transmitting a purchase request for the NFT associated with the NFT art to the server device 200 (step S4). The server device 200 then executes information processing in response to the NFT purchase request from the buyer 1 (step S5). As part of the information processing in response to the NFT purchase request, the server device 200 sells the NFT associated with the digital content created by the original copyright holder to the buyer 1 and records the information of the buyer 1 who requested the NFT purchase on the blockchain as the owner of the sold NFT. After executing the information processing in response to the NFT purchase request, the server device 200 transmits the digital content corresponding to the purchased NFT to the buyer 1 terminal 70 (step S6).

[0018] Here, the NFT Marketplace records transaction history on the blockchain, but does not use the blockchain to check whether the digital art being put up for sale is an original or a replica. As a result, copied NFT art (replica art) can be put up for sale on the NFT Marketplace, which could lead to the circulation of replica art (step S700).

[0019] The processing flow performed in step S700 will be specifically described. The buyer 1 terminal 70 performs the procedure to list a copy of the purchased digital content (step S7). If the buyer 1 correctly completes the NFT issuance request procedure in step S7, the server device 200 issues an NFT associated with the copy art and records information about the buyer 1 as the owner of the issued NFT in the blockchain. This prevents copy art that has the same appearance as the original but has a different NFT embedded in it from being listed on the NFT marketplace. After executing information processing in response to the NFT issuance request, the server device 200 sends a registration completion notification to the buyer 1 terminal 70 (step S8). The buyer 2 terminal 80 performs the purchase procedure by sending a purchase request for the NFT associated with the copy art to the server device 200 (step S9). If the procedure for requesting the purchase of an NFT has been correctly carried out by the purchaser 2, the server device 200 executes information processing in accordance with the NFT purchase request and transmits digital content (replicated art) corresponding to the purchased NFT to the purchaser 2 terminal 80 (step S10).

[0020] In this way, Buyer 2 may purchase a copy of art without realizing that it is a copy. If Buyer 2 purchases digital art thinking it is an original, but it turns out to be a copy, it will undermine the trust in transactions on the NFT marketplace. Because different NFTs are associated with originals and copies, it is conceivable to detect copy art based on the similarity of the digital content's appearance, differences in the NFTs, and transaction history. However, there are limitations to detecting copy art in real time in an NFT marketplace where a large amount of NFT art is circulating.

[0021] To address this issue, the NFT marketplace of this embodiment makes it difficult to copy NFT art. Specifically, content information for digital content offered on the NFT marketplace 10 is divided into two pieces of information, which are managed separately, allowing only the purchaser to reproduce the digital content using the two pieces of information. For example, if the digital content is a still image or a moving image, the digital content can be reproduced by displaying the digital content on a display. The NFT marketplace 10 of this embodiment will now be described.

[0022] As shown in FIG. 1, the NFT marketplace 10 includes a server device 20 and two blockchains (a first blockchain 30 and a second blockchain 40).

[0023] The server device 20 is a computer that executes transactions of NFT art. For example, a server device, a cloud, a PC, or the like can be used as the server device 20. The server device 20 uses two blockchains (a first blockchain 30 and a second blockchain 40) to manage content information for digital content offered on the NFT marketplace 10.

[0024] Specifically, the server device 20 generates two pieces of information (first information and second information) from the content information. The first information is the content information excluding the second information. The second information is a part of the content information. The content information can be generated by combining the first information and the second information.

[0025] The server device 20 manages the content information in the first blockchain 30. Specifically, the server device 20 issues an NFT associated with the content information, and records information about the original author who requested the issuance of the NFT in the first blockchain 30 as attribute information (e.g., owner information) of the issued NFT.

[0026] Meanwhile, the server device 20 manages the second information using a means separate from the first blockchain 30. Possible means separate from the first blockchain 30 include a means of management using a blockchain different from the first blockchain 30, or a means of storing the information in a secure database. In this embodiment, an example will be described in which the second information is managed using a second blockchain 40 (a blockchain different from the first blockchain 30). The server device 20 issues an NFT associated with the second information and records information about the original author who requested the issuance of the NFT in the blockchain as information about the holder of the issued NFT.

[0027] Here, not only information about the holder of the NFT but also identification information of the viewing device as attribute information of the second information is recorded in the second blockchain 40. The viewing device will be described later.

[0028] The server device 20 allows users to view the content information in the NFT marketplace and accepts purchase requests for NFTs associated with the content information. By distributing the content information in the NFT marketplace, users can view the digital content put up for sale on the market, allowing them to consider purchasing the digital content.

[0029] If the digital content includes color, the second information may be information corresponding to the color information of the content. In this case, the second information is a lookup table in which information indicating the color (e.g., RGB values) as pixel values ​​for each pixel is associated. The second information may be identification information (e.g., a color ID or a color ID) that uniquely identifies the lookup table, together with or instead of the lookup table. The color information may include all of hue, saturation, and brightness, or may not include all of them. The first information is information that does not include color information of the content. For example, the first information is information obtained by excluding regular color information (second color information) from the content information. Alternatively, the first information may be information obtained by adding dummy color information indicating an irregular dummy color instead of the color information excluded from the content information. The dummy color information is, for example, binarized information obtained by converting regular color information into two values ​​(e.g., white and black). The first information may be information obtained by removing at least some information from the content information, and may be information that makes it impossible to completely reproduce the digital content due to the removal of some information. When dummy information is added to the first information, the first information may include information indicating that the dummy information is not regular information (second information). Furthermore, the first information may include information (incomplete information) indicating that the first information is regular content with some information (second information) removed. The following description will be given taking as an example a case where the digital content is content that includes color and the second information is regular color information in the content information.

[0030] As information processing in response to a purchase request for an NFT associated with content information, the server device 20 records information about the purchaser of the NFT (the holder of the next NFT) in the first blockchain 30. Examples of information about the purchaser of the NFT (the holder of the next NFT) include a purchaser ID and a purchase number.

[0031] Here, as information processing in response to the purchase request for the NFT associated with the content information, the server device 20 of this embodiment further transmits a registration request to the terminal (e.g., purchaser 1 terminal 70) that notified the purchase request for the NFT associated with the content information. The registration request is a notification requesting registration of an appreciation device. The appreciation device is a device on which the purchaser who purchased the NFT enjoys the digital content corresponding to the purchased NFT, and in the example of this figure, it is purchaser 1 display 71. The purchaser 1 terminal 70 and the purchaser 1 display 71 may be the same device or may be different devices. The server device 20 records the device identification information of the appreciation device registered by the purchaser (e.g., purchaser 1 display 71) in the second blockchain 40 in association with the second information of the digital content purchased by the purchaser.

[0032] The server device 20 transmits first information and second information corresponding to the purchased NFT to the viewing device registered by the purchaser (e.g., purchaser 1 display 71). After transmitting the first information, the server device 20 transmits second information in response to a request from the viewing device. The server device 20 performs device authentication to determine whether the device requesting the transmission of the second information is a device registered as a viewing device. Only when the device authentication determines that the device requesting the second information is a viewing device, does the server device 20 transmit the second information to that device (viewing device). Specific details of the process by which the server device 20 performs device authentication will be described in detail later.

[0033] In this way, in the trading system 1 of this embodiment, when a purchaser purchases an NFT associated with content information, the purchaser is sent first information and prompted to register a viewing device, and second information is sent only to the registered viewing device. This allows authentic digital content to be reproduced using the second information (e.g., authentic color information) only on the viewing device. Because the purchaser is notified of the first information, which excludes some of the content information, any attempt to copy the content would result in a copy of the first information. This makes it difficult to copy NFT art. Therefore, the trading system 1 of this embodiment makes it possible to make copying NFT art difficult.

[0034] 2 is a block diagram illustrating the configuration of a server device according to an embodiment. As shown in FIG. 2, the server device 20 includes an acquisition unit 21, a generation unit 22, a first management unit 23, a second management unit 24, a first correspondence unit 25, a second correspondence unit 26, and a storage unit 27.

[0035] The acquisition unit 21 acquires various types of information. For example, when an NFT issuance request is made from a terminal device (e.g., the original copyright holder terminal 50) of a user who wishes to list digital content on the NFT marketplace 10, the NFT marketplace 10 issues an NFT in response to the NFT issuance request. When an NFT is issued on the NFT marketplace 10, the acquisition unit 21 acquires content information of the digital content corresponding to the issued NFT. This content information is notified to the NFT marketplace 10, for example, from the terminal device (e.g., the original copyright holder terminal 50) of the user who made the NFT issuance request, along with the NFT issuance request. The acquisition unit 21 outputs the acquired content information to the generation unit 22. The acquisition unit 21 stores the acquired content information in the storage unit 27 as distribution management information 270.

[0036] The generation unit 22 generates first information and second information from the content information. The generation unit 22 generates the first information by removing color information (second information) indicating the color of the digital content from the content information. The generation unit 22 may generate first information including incomplete information. The generation unit 22 generates color information indicating the correct color of the digital content as the second information. The generation unit 22 stores the generated first information and second information in the storage unit 27 as distribution management information 270.

[0037] The first management unit 23 distributes NFTs (non-fungible tokens) associated with the content information in the NFT marketplace 10. The NFT marketplace 10 is a market where holders of NFTs (non-fungible tokens) are managed using a blockchain. The first management unit 23 issues NFTs associated with the content information and records information about the original author who requested the issuance of the NFT in the first blockchain 30 as information about the holder of the issued NFT. As a result, the first management unit 23 lists digital content by distributing the NFTs (non-fungible tokens) associated with the content information in the NFT marketplace 10 as a subject of trading in the NFT marketplace 10. Here, the first management unit 23 may list content consisting only of first information in the NFT marketplace 10. In this case, the first management unit 23 makes the non-fungible token associated with the first information the subject of trading in the NFT marketplace 10, and distributes the digital content corresponding to the first information in the NFT marketplace 10, that is, in a market managed by holders of the non-fungible token using blockchain.

[0038] The second management unit 24 manages the second information in association with the first information. The second management unit 24 manages the second information, for example, by managing an NFT (non-fungible token) associated with the second information using a blockchain. The second management unit 24 issues an NFT associated with the second information and records information about the original author who requested the issuance of the NFT in the second blockchain 40 as information about the holder of the issued NFT. In this way, the second management unit 24 manages the second information. Alternatively, the second management unit 24 may manage the second information by storing information (circulation management information 270) that associates the first information with the second information in the memory unit 27.

[0039] The first response unit 25 performs processing corresponding to the transaction (purchase) of NFT art (digital content) that has been put up for sale on the NFT marketplace 10. When the buyer 1 purchases an NFT (non-fungible token) associated with content information, an NFT purchase request is notified to the NFT marketplace 10 from the buyer 1 terminal 70. The first response unit 25 acquires the NFT purchase request notified to the NFT marketplace 10 via the acquisition unit 21 of the server device 20. As information processing in response to the NFT purchase request, the first response unit 25 sells the NFT associated with the content information to the buyer 1 and records information about the buyer 1 who made the NFT purchase request in the first blockchain 30 as information about the holder of the sold NFT. As a result, the holder of the NFT becomes the buyer 1, and a sale and purchase of the digital content is established on the NFT marketplace 10.

[0040] When a sale of digital content is completed, the first response unit 25 transmits a registration request to the purchaser 1 terminal 70, which is the terminal device of the purchaser 1. The registration request is a notification requesting registration of the device (viewing device) on which the purchaser 1 will view the digital content purchased. This registration request, for example, requests notification of the identification information of the viewing device. The identification information of the viewing device may be, for example, the model name of the viewing device, a serial number unique to the viewing device, or the like. This identification information of the viewing device is used as signature information used to verify whether or not to comply with the request notification for second information, which will be described later.

[0041] In response to the registration request, the purchaser 1 terminal 70 notifies the purchaser 1 display 71, for example, as identification information of the viewing device. The first correspondence unit 25 stores the identification information of the viewing device notified in response to the registration request in the storage unit 27 as information associated with the content (distribution management information 270). The first correspondence unit 25 records the device identification information of the viewing device in the second blockchain 40 as attribute information of the second information, in association with the NFT corresponding to the second information.

[0042] The second correspondence unit 26 transmits second information corresponding to the digital content purchased by the purchaser to the viewing device based on the identification information of the viewing device stored in the storage unit 27. For example, in the trading system 1, a program (hereinafter referred to as a display program) for displaying digital content using the first information and the second information is prepared in advance for users of the NFT marketplace 10. Here, the server device 20 transmits the first information to the purchaser 1 terminal 70 along with a guide message such as, "Please copy the first information to your viewing device and display the digital content on the viewing device." Alternatively, the server device 20 may transmit the first information directly to the viewing device. Furthermore, the server device 20 transmits the display program to the terminal device (e.g., the purchaser 1 terminal 70) of the user who registered the viewing device along with a guide message such as, "You can display the digital content by installing the display program on your viewing device." The purchaser installs the display program on the viewing device in accordance with the guide message and stores an electronic file corresponding to the first information on the viewing device.

[0043] When a purchaser operates the viewing device to start the display program and display the digital content, the viewing device executes a function to acquire the second information via the display program. Specifically, the viewing device notifies the server device 20 of its own device identification information and transmits a request for the second information to the server device 20. Here, a third-party device masquerading as the viewing device may notify the server device 20 of its own device identification information and transmit a request for the second information to the server device 20.

[0044] The second response unit 26 acquires a request notification from a device (including a viewing device and a third-party device) via the acquisition unit 21 of the server device 20. Upon acquiring the request notification, the second response unit 26 determines, based on the device identification information included in the request notification, whether the device (terminal device) that notified the request notification is a viewing device registered by the purchaser. For example, upon acquiring the request notification, the second response unit 26 refers to the storage unit 27 based on the device identification information included in the request notification and determines whether the device corresponding to the device identification information is registered as a viewing device. If the device identification information included in the request notification is stored as the identification information of a viewing device in the distribution management information 270 of the storage unit 27, the second response unit 26 determines that the device corresponding to the device identification information is registered as a viewing device. On the other hand, if the device identification information included in the request notification is not stored as the identification information of a viewing device in the distribution management information 270 of the storage unit 27, the second response unit 26 determines that the device corresponding to the device identification information is not registered as a viewing device. If the second response unit 26 determines that the device (terminal device) that sent the request notification is a viewing device, the second response unit 26 transmits the second information of the digital content associated with the viewing device to the device (viewing device) that sent the request notification. As a result, the second information is transmitted from the server device 20 to the viewing device.

[0045] The viewing device receives the second information from the server device 20. Upon receiving the second information, the viewing device displays the authentic digital content using the received second information via the display program. This allows the authentic digital content to be reproduced only on the viewing device (e.g., the buyer 1 display 71) registered by the buyer 1 who purchased the NFT.

[0046] The storage unit 27 is configured by a storage medium, such as a hard disk drive (HDD), flash memory, electrically erasable programmable read-only memory (EEPROM), random access read / write memory (RAM), read-only memory (ROM), or any combination of these storage media. The storage unit 27 stores distribution management information 270. The distribution management information 270 can be, for example, a nonvolatile memory.

[0047] FIG. 3 is a diagram illustrating an example of distribution management information 270 in an embodiment. The distribution management information 270 is information related to digital content that is put up for sale on the NFT marketplace 10 and distributed in the market as a trading subject. The distribution management information 270 stores information corresponding to items such as a content ID, content information, first information, second information, NFT holder, and identification information of the viewing device. The content ID is identification information that uniquely identifies digital content put up for sale on the NFT marketplace 10. The content information is information about the digital content put up for sale on the NFT marketplace 10. If the digital content is a still image or a moving image, for example, the content information is an image file representing the still image or the moving image. The first information is information obtained by excluding a portion of the content information (second information). For example, the first information is image information of a binary image obtained by excluding color information (information indicating the RGB values ​​for each pixel) included in the content information as second information and assigning binary information, in which the RGB values ​​are binarized to either white or black, as dummy color information instead of the color information. The second information is information removed from the content information when the first information is generated. The NFT holder is information indicating the holder who holds the NFT associated with the first information. This information indicating the NFT holder is information managed using a blockchain. For example, each time an NFT is bought and sold and the holder of the NFT changes, information indicating the NFT holder is recorded in the first blockchain 30. The identification information of the viewing device is identification information of a device registered by a purchaser of an NFT as an viewing device for viewing digital content corresponding to the purchased NFT. The identification information may be any information that can identify the device, and for example, a serial number may be used. The identification information of the viewing device is information managed using a blockchain. For example, each time an NFT is bought and sold and the viewing device is registered by the purchaser of the NFT, the identification information of the viewing device is recorded in the second blockchain 40.

[0048] 4 and 5 are sequence diagrams illustrating the flow of processing performed by the trading system 1 of this embodiment. Fig. 4 shows a series of steps from when digital art is put up for sale on the NFT marketplace 10 to when the put up digital art is purchased and the purchased digital art becomes available for viewing (steps S100 to S113). Fig. 4 also shows the flow of processing when replicated art is put up for sale on the NFT marketplace (step S1140). Fig. 5 shows the flow of processing when digital art put up for sale on the NFT marketplace 10 is resold.

[0049] 4, original copyright holder terminal 50 performs the listing procedure by requesting server device 20 to issue an NFT corresponding to the digital content created by the original copyright holder (step S100). Original copyright holder terminal 50 requests the issuance of an NFT corresponding to the digital content by transmitting to server device 20, for example, an original copyright holder ID that identifies the original copyright holder, content information of the digital content to be listed, and the like.

[0050] The server device 20 executes information processing in response to the NFT issuance request (step 101). The server device 20 assigns a content ID to the put-upon digital content and records the original copyright holder, registration number, content information, seller, and the date and time of putting up, in association with each other. The server device 20 generates first information and second information from the content information of the digital content for which the NFT issuance request has been received. The server device 20 issues an NFT associated with the content information and records information about the original copyright holder as the owner of the issued NFT in the first blockchain 30 (not shown in FIG. 4). The first blockchain 30 corresponds to a blockchain in a conventional trading system. Once an NFT associated with the content information is issued and its owner is recorded in the blockchain, the listing on the NFT marketplace 10 is completed, and the digital content is circulated as a trading subject. Note that the server device 20 may also record information such as the digital content ID of the put-upon digital content and the original copyright holder associated with the content ID in association with the NFT for the digital content in the first blockchain 30.

[0051] The server device 20 also makes a registration request to the second blockchain 40 to register the second information (step S102). For example, the NFT marketplace 10 issues an NFT associated with the second information and requests the second blockchain 40 to record information about the original author as the owner of the issued NFT in the second blockchain 40. In response to the registration request notified by the server device 20, the second blockchain 40 records information about the original author as the owner of the NFT included in the registration request (step S103). Once the recording of the NFT owner is complete, the second blockchain 40 transmits a registration completion notice to the server device 20 indicating that the registration of the second information has been completed (step S104). Upon receiving the registration completion notice from the second blockchain 40 indicating that the registration of the second information has been completed, the server device 20 transmits a registration completion notice to the original copyright holder terminal 50 indicating that the registration of the item has been completed (step S105).

[0052] Meanwhile, the purchaser 1 terminal 70 performs the purchase procedure by transmitting a purchase request for the NFT associated with the NFT art to the server device 20 (step S106). The server device 20 executes information processing in response to the NFT purchase request from the purchaser 1 (step S107). The server device 20 records the purchaser, purchase number, etc. in association with the content ID of the purchased digital content. The server device 20 sells the NFT that is the subject of the NFT purchase request (the NFT associated with the first information) to the purchaser 1, and records information about the purchaser 1 who made the NFT purchase request in the first blockchain 30 as information about the owner of the sold NFT. The server device 20 may also record the purchase number, etc. in the first blockchain 30.

[0053] The server device 20 transmits a registration request to the purchaser 1 terminal 70 to prompt the purchaser 1 to register the viewing device. Upon receiving a response to the registration request from the purchaser 1 terminal 70, the server device 20 registers the viewing device by storing the identification information of the viewing device included in the response in the storage unit 27 as distribution management information 270. Once the viewing device is registered, the server device 20 transmits first information corresponding to the NFT purchased by the purchaser 1 to the purchaser 1 terminal 70 (step S108). The server device 20 also transmits a display program to the purchaser 1 terminal 70.

[0054] The purchaser 1 terminal 70 performs processing to display (reproduce) the digital content on the viewing device (purchaser 1 display 71) (step S109). In response to an operation by the purchaser 1, the purchaser 1 terminal 70 installs a display program on the purchaser 1 display 71 and stores the first information in the purchaser 1 display 71.

[0055] The purchaser 1 display 71 displays (reproduces) the digital content (step S110). When a display program is started in response to an operation by purchaser 1 and an operation to display the digital content is performed, the purchaser 1 display 71 transmits its own (purchaser 1 display 71's) device identification information to the server device 20, thereby issuing a request to send the second information (step S111). The server device 20 receives the request transmitted from the purchaser 1 display 71.

[0056] The server device 20 performs processing to transmit the second information (step S112). Based on the device identification information included in the request notification received from the purchaser 1 display 71, the server device 20 determines whether the device (terminal device) that sent the request notification is a registered viewing device. If the device that sent the request notification is a registered viewing device, the server device 20 transmits the second information to the device that sent the request notification, i.e., the viewing device, purchaser 1 display 71 in this figure (step S113). The purchaser 1 display 71 displays the digital content using the first information and the second information. This reproduces the legitimate digital content on the purchaser 1 display 71.

[0057] Here, we will explain the processing when reproduced art is put up for sale, as shown in step S1140. Assume that buyer 1 terminal 70 has reproduced digital content purchased from NFT marketplace 10 and gone through the process of putting up the reproduced art (step S114). Buyer 1 has no way of knowing that the first information, among the content information of the digital content, is circulating on NFT marketplace 10, or that the second information is acquired by the viewing device when displaying the digital content. Therefore, buyer 1 recognizes that the first information circulating on NFT marketplace 10 is the content information of the digital content itself. Therefore, in step S114, buyer 1 terminal 70 reproduces the first information as content information of the digital content and goes through the process of putting up the reproduced art.

[0058] The server device 20 attempts to generate first information and second information from content information (first information as content information) corresponding to the NFT issuance request in step S114. For ease of explanation, the first information as content information corresponding to the NFT issuance request in step S114 is referred to as existing first information. Furthermore, first information generated from the existing first information is referred to as new first information. Second information generated from the existing first information is referred to as new second information. Here, it is assumed that the existing first information contains incomplete information. In this case, the server device 20 can determine whether the listed digital content is reproduced art based on whether the content information (existing first information) of the listed digital content contains incomplete information. For example, before generating the first information and the second information from the content information, the generation unit 22 determines whether the content information contains incomplete information. If the content information contains incomplete information, the generation unit 22 determines that the content is a reproduced product. In this case, the put-upon digital content is determined to be copied art, and measures such as refusing to allow it to be put up for sale on the NFT marketplace 10 are taken. On the other hand, if the content information does not include incomplete information, the generation unit 22 determines that the content is genuine. In this case, the generation unit 22 generates first information and second information from the content information.

[0059] However, if the marketplace does not have a function for checking whether or not the digital art put up for sale is a copy at the time of listing, as in conventional NFT marketplaces, the listing of existing first information (copy art) as a copy of legitimate digital content may be accepted, and (new first information of) the copy art may end up in circulation. The trading system 1 of the present embodiment is designed to make it easy to detect copy art, even when copy art is put up for sale on the market using such a conventional acceptance function.

[0060] When the reproduced art (or new first information thereof) is circulated in the market, new first information and new second information are generated from the existing first information (reproduced art), NFTs corresponding to the reproduced art and the second information thereof are issued, and information about their owners is recorded in the blockchain. Specifically, information about the owner of the NFT associated with the reproduced art is stored in the first blockchain 30, and information about the owner of the NFT associated with the new second information is stored in the second blockchain 40. The server device 20 sends a registration completion notice to the buyer 1 terminal 70 (step S115). The buyer 2 terminal 80 performs the purchase procedure by sending a purchase request for the NFT associated with the reproduced art (or new first information thereof) to the server device 20 (step S116). Here, the server device 20 executes the same processes as steps S107 and S108, and, as a process corresponding to step S108, sends the new first information and a display program to the buyer 2 terminal 80 (step S117). The purchaser 2 terminal 80 executes the processes shown in steps S109 to S110. Specifically, the purchaser 2 terminal 80 installs a display program on the viewing device (purchaser 2 display 81) registered when the purchaser 2 purchased the NFT, and stores new first information in the purchaser 2 display 81. The purchaser 2 display 81 transmits a request notice to the server device 20 via the display program, requesting transmission of new second information, and receives the new second information from the server device 20 in response to the request notice. Here, the display program determines whether the content information based on the new first information and the new second information (i.e., the existing first information) contains incomplete information. If incomplete information is contained, the purchaser 2 display 81 notifies the server device 20 via the display program (step S118). This notification notifies that the digital content purchased by purchaser 2 is copied art. When the server device 20 receives the notification, it identifies the seller (here, buyer 1) who listed the target digital content (digital content purchased by buyer 2) and takes measures against the seller (buyer 1), such as suspending their use of the market (step S119).With this configuration, even if a copy of art is put up for sale, it becomes easy to detect the copy of art.

[0061] The processing shown in steps S200 to S213 of Figure 5 is similar to steps S100 to S113 of Figure 4, and therefore a description thereof will be omitted. The buyer 1 terminal 70 performs procedures to resell the digital art purchased from the NFT marketplace 10 (step S214). As in step S114, the buyer 1 has no way of knowing that the first information, among the content information of the digital content, is circulating in the NFT marketplace 10, or that the second information is acquired by the viewing device when the digital content is displayed. Therefore, the buyer 1 recognizes that the first information circulating in the NFT marketplace 10 is the content information of the digital content itself. Therefore, in step S214, the buyer 1 terminal 70 performs resale procedures to resell the first information as content information of the legitimate digital content.

[0062] When the server device 20 accepts the resale procedure, it references the distribution management information 270 of the digital content to be resold, reads the identification information of the viewing device registered by the purchaser 1 at the time of purchase, and identifies the viewing device. The server device 20 updates the owner of the NFT associated with the first information to be resold, and records information that changes the owner from the purchaser 1 to the market administrator in the first blockchain 30. The server device 20 issues a return request to the viewing device (the purchaser 1 display 71 in this figure) requesting the return of the second information (step S215). This return request includes, for example, content instructing the second information to be returned to the second blockchain 40. In response to the return request, the purchaser 1 display 71 transmits the second information to the second blockchain 40 via a display program (step S216). The second blockchain 40 updates the owner of the NFT associated with the second information, and records information that changes the owner from the purchaser 1 to the market administrator in the second blockchain 40. The second blockchain 40 transmits a registration completion notice to the buyer 1 terminal 70 indicating that the registration of the second information has been completed (step S217). Upon receiving the registration completion notice from the second blockchain 40, the server device 20 transmits a registration completion notice to the buyer 1 terminal 70 indicating that the resale procedure has been completed (step S218).

[0063] The purchaser 2 terminal 80 completes the purchase procedure by sending a purchase request for the NFT of the digital content put up for resale to the server device 20 (step S219). The subsequent processes shown in steps S220 to S226 are the same as the processes shown in steps S207 to S213, and therefore their explanation will be omitted.

[0064] As described above, the server device 20 of the embodiment includes a generation unit 22, a first response unit 25, and a second response unit 26. The generation unit 22 generates first information, which does not include color information of the content, and second information, which corresponds to color information, based on the digital content (an example of content) to be traded. The first response unit 25 transmits the first information and a registration request requesting registration of a viewing device (viewing terminal device) for viewing the content to a terminal device of a purchaser who has completed the content purchase procedure. The first response unit 25 stores the identification information of the viewing device notified in response to the registration request in the storage unit 27. When the second response unit 26 receives a transmission request requesting transmission of the second information, the second response unit 26 determines whether the identification information of the terminal device included in the transmission request matches the identification information of the viewing device stored in the storage unit 27. If the second response unit 26 determines that the identification information matches, the second response unit 26 transmits the second information to the viewing device. As a result, the server device 20 of the embodiment separates the content information into two pieces of information, the first information and the second information, and manages them separately. Authentic content based on the first information and the second information is displayed only on the viewing device of the purchaser who purchased the first information. Because the purchaser has purchased the first information, if they attempt to sell a replica, they will be selling a replica that replicates the first information. Because some information has been deleted from the first information, it is difficult to imitate an authentic product. Therefore, it is possible to make it difficult to copy NFT art. Furthermore, the server device 20 of the embodiment transmits the second information to the terminal device that notified the request notification only if the terminal device that notified the request notification is a viewing device (registered in the storage unit 27). Therefore, the second information can be notified only to viewing devices that have been registered in advance, thereby preventing fraud such as an unregistered terminal device masquerading as a viewing device and requesting the second information.

[0065] The server device 20 of the embodiment further includes a first management unit 23. The first management unit 23 uses a blockchain to list content on a market managed by holders of non-fungible tokens associated with the content. This allows the buying and selling history of content listed on the market to be managed so that it is not tampered with. The server device 20 of the embodiment further includes a first management unit 23. The first management unit 23 may use a blockchain to list content consisting only of first information on a market managed by holders of non-fungible tokens. This allows the first information of content listed on the market to be traded, and the buying and selling history of the first information to be managed so that it is not tampered with. In the server device 20 of the embodiment, the first correspondence unit stores identification information of the viewing device in the listing management information 270 (information in which the first information and second information are associated with each other). This allows the server device 20 of the embodiment to store the first information of content, the second information, and the viewing device information in association with each other.

[0066] The server device 20 of the embodiment also includes a second management unit 24. The second management unit 24 manages the second information by managing NFTs (non-fungible tokens) associated with the second information using the second blockchain 40. This allows the server device 20 of the embodiment to manage the history of attribute information (e.g., holders) of the second information in association with the NFTs managed by the blockchain. Therefore, the history of attribute information (e.g., holders) of the second information can be managed in a manner that makes it difficult to tamper with the history.

[0067] In addition, in the server device 20 of the embodiment, the first response unit 25 transmits a display program for displaying content on the viewing device based on the first information and the second information. The display program executes a request notification for requesting the second information by causing the viewing device to transmit identification information of the viewing device in response to an operation to display content on the viewing device. The display program displays the content on the viewing device using the second information notified to the viewing device in response to the request notification. This allows the server device 20 of the embodiment to display legitimate content only on the viewing device.

[0068] Furthermore, in the server device 20 of the embodiment, the first information includes incomplete information indicating that the information is information in which some information has been removed from the content. The display program determines whether the content to be displayed on the viewing device is a copy depending on whether the content information based on the first information and the second information includes incomplete information. In the server device 20 of the embodiment, when reproduced art made by reproducing the digital content purchased by purchaser 1 is put up for sale, a copy of the first information is put up for sale. The first information includes incomplete information. When displaying the content on the viewing device, the display program determines whether the content information includes incomplete information, thereby making it easy to determine whether the content purchased by purchaser 2 is a copy.

[0069] Furthermore, in the server device 20 of the embodiment, the first information includes incomplete information indicating that the information is information in which some information has been removed from the content. The generation unit 22 determines whether the content is a copy depending on whether the content information includes the incomplete information. As a result, in the server device 20 of the embodiment, the first information includes the incomplete information, making it easy to determine whether the content is a copy depending on whether the content information includes the incomplete information.

[0070] Here, the basic configuration of the server device of the trading system will be described using FIG. 7. FIG. 7 is a block diagram showing the basic configuration of the server device 2 in an embodiment. The server device 2 includes a generation unit 3, a first management unit 4, a second management unit 5, a first correspondence unit 6, and a second correspondence unit 7. The generation unit 3 generates first information, which is content information of the content to be traded, excluding color information of the content, and second information, which is color information of the content information. The first management unit 4 circulates non-fungible tokens associated with the first information in a market managed by holders of non-fungible tokens using a blockchain. The second management unit 5 manages the second information in association with the first information. The first correspondence unit 6 transmits a registration request to a terminal device of a purchaser who purchased a non-fungible token associated with the first information, requesting registration of a viewing device on which the purchaser will view the content purchased. The first correspondence unit 6 stores the identification information of the viewing device notified in response to the registration request in a memory unit. The second correspondence unit 7 transmits second information corresponding to the content purchased by the purchaser to the viewing device based on the identification information of the viewing device stored in the storage unit.

[0071] 1, a program for realizing each function of the trading system 1, the NFT marketplace 10, and the server device 20 may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed to perform location detection. Note that the term "computer system" here includes hardware such as an OS and peripheral devices.

[0072] Furthermore, if a WWW system is used, the term "computer system" also includes the homepage provision environment (or display environment). Furthermore, "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording medium" also includes devices that retain programs for a certain period of time, such as volatile memory within a computer system that serves as a server or client. The program may be one that realizes part of the aforementioned functions, or it may be one that realizes the aforementioned functions in combination with a program already stored in the computer system. The program may also be stored on a designated server, and distributed (e.g., downloaded) via a communication line in response to requests from other devices.

[0073] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment and includes designs within the scope of the gist of the present invention. For example, in the above-described embodiment, an example in which management is carried out using a blockchain in an NFT marketplace has been described, but this is not limiting. The history of buying and selling in the market may also be managed using a technology other than the blockchain, such as a directed acyclic graph (DAG), which manages data in a distributed manner while ensuring the accuracy of transactions.

[0074] 1 Trading system 10 NFT marketplace 2, 20, 200 Server device 21 Acquisition unit 3, 22 Generation unit 4, 23 First management unit 5, 24 Second management unit 6, 25 First correspondence unit 7, 26 Second correspondence unit 27 Storage unit 270 Distribution management information 30 First blockchain 40 Second blockchain 50 Original copyright holder terminal 70 Purchaser 1 terminal 71 Purchaser 1 display 80 Purchaser 2 terminal 81 Purchaser 2 display

Claims

1. A server device comprising: a generation unit that generates, based on the content of the content that is the subject of a transaction, first information that does not have color information of the content and second information that corresponds to the color information; a first response unit that transmits the first information and a registration request requesting registration of a viewing terminal device that will view the content to a terminal device of a purchaser who has completed the purchase procedure for the content, and stores in a memory unit the identification information of the viewing terminal device notified in response to the registration request; and a second response unit that, when receiving a transmission request requesting the transmission of the second information, determines whether the identification information of the terminal device included in the transmission request matches the identification information of the viewing terminal device stored in the memory unit, and transmits the second information to the viewing terminal device when it is determined that they match.

2. The server device according to claim 1, further comprising a first management unit that uses a blockchain to allow the content to be put up for sale on a market managed by holders of non-fungible tokens associated with the content.

3. The server device according to claim 1, further comprising a first management unit that uses a blockchain to allow content consisting only of the first information to be put up for sale on a market managed by holders of non-fungible tokens associated with the content.

4. The server device according to claim 1, wherein the first correspondence unit stores identification information of the viewing terminal device in commodity management information in which the first information and the second information are associated with each other.

5. The server device according to claim 1, further comprising a second management unit that manages the second information by managing non-fungible tokens associated with the second information using a blockchain.

6. The server device described in claim 1, wherein the first response unit transmits a display program for displaying the content on the viewing terminal device based on the first information and the second information, and the display program executes a request notification requesting the second information by causing the viewing terminal device to transmit identification information of the viewing terminal device in response to an operation to display the content, and causes the viewing terminal device to display the content using the second information notified to the viewing terminal device in response to the request notification.

7. The server device described in claim 6, wherein the first information includes incomplete information indicating that some information has been removed from the content, and the display program determines whether the content to be displayed on the viewing terminal device is a copy depending on whether the incomplete information is included in the content based on the first information and the second information.

8. The server device of claim 1, wherein the first information includes incomplete information indicating that the content has had some information removed, and the generation unit determines whether the content is a copy depending on whether the content includes the incomplete information.

9. A transaction system comprising: a server device according to any one of claims 1 to 8; and the viewing terminal device.

10. A transaction method performed by a server device which is a computer, wherein an acquisition unit generates first information that does not have color information of the content and second information that corresponds to the color information based on the content of the content that is the subject of the transaction; a first response unit transmits the first information and a registration request to the terminal device of the purchaser who has completed the purchase procedure for the content, requesting registration of a viewing terminal device for viewing the content, and stores in a memory unit the identification information of the viewing terminal device notified in response to the registration request; and a second response unit, when receiving a transmission request requesting transmission of the second information, determines whether the identification information of the terminal device included in the transmission request matches the identification information of the viewing terminal device stored in the memory unit, and if it determines that they match, transmits the second information to the viewing terminal device.

11. A program that causes a server device, which is a computer, to generate first information that does not include color information of the content based on the content of the content that is the subject of a transaction, and second information that corresponds to the color information; sends the first information and a registration request requesting registration of a viewing terminal device that will view the content to a terminal device of a purchaser who has completed the purchase procedure for the content, stores in a memory unit the identification information of the viewing terminal device notified in response to the registration request; when a transmission request requesting the transmission of the second information is received, determines whether the identification information of the terminal device included in the transmission request matches the identification information of the viewing terminal device stored in the memory unit, and if it is determined that they match, sends the second information to the viewing terminal device.

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