Control method, control device, and program

Abstract

This control method is executed by a first device used by a first user among a plurality of devices sharing a distributed ledger for managing content owners in a distributed ledger system including the plurality of devices. The control method comprises: transmitting, through short-range wireless communication to a second device used by a second user among the plurality of devices, identification information of a smart contract including a process for providing content in accordance with a content provision condition accepted by the first user (S202); receiving, through short-range wireless communication, transaction data including identification information of the second device and instruction information for instructing execution of the smart contract (S205); storing the received transaction data in the distributed ledger (S206); and changing the owner of the content from the first user to the second user by executing the smart contract (S207).

Description

[Technical field]

[0001] The present invention relates to a control method, a control device, and a program. [Background technology]

[0002] A technology has been disclosed for providing content (specifically, exchanging game characters) by utilizing short-range wireless communication (also called passing communication) between terminals that move together with a user (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-139362 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is a problem in that it is difficult to reflect the conditions of provision that the user accepts when providing content.

[0005] Therefore, the present invention provides a control method that can provide content based on Passing Communication while reflecting the conditions for providing content that a user accepts. [Means for solving the problem]

[0006] A control method according to one embodiment of the present invention is a control method executed by a first device used by a first user in a distributed ledger system having a plurality of devices each holding a distributed ledger that manages the owner of content, the control method transmitting, via short-range wireless communication, to a second device used by a second user among the plurality of devices, identification information of a smart contract including a process of providing the content in accordance with conditions for providing the content permitted by the first user, receiving, via short-range wireless communication, transaction data including identification information of the second device and instruction information for instructing execution of the smart contract, storing the received transaction data in the distributed ledger, and executing the smart contract, thereby changing the owner of the content from the first user to the second user.

[0007] These comprehensive or specific aspects may be realized as a system, an apparatus, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be realized as any combination of a system, an apparatus, an integrated circuit, a computer program, and a recording medium. Effect of the Invention

[0008] According to the control method of the present invention, it is possible to provide content based on Passing Communication while reflecting the conditions for providing content that the user accepts. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram illustrating a configuration of a management system according to an embodiment. [Diagram 2] FIG. 2 is an explanatory diagram that illustrates the provision of content in the management system according to the embodiment. [Diagram 3] FIG. 3 is a block diagram illustrating a schematic configuration of a terminal according to the embodiment. [Figure 4] FIG. 4 is a first sequence diagram showing the processing of the management system in the embodiment. [Diagram 5] FIG. 5 is a second sequence diagram showing the processing of the management system in the embodiment. [Figure 6] FIG. 6 is a flow chart showing the processing of the terminal in the embodiment. [Figure 7] FIG. 7 is an explanatory diagram illustrating a first example of transaction data in the embodiment. [Figure 8] FIG. 8 is an explanatory diagram illustrating a second example of transaction data according to the embodiment. [Figure 9] FIG. 9 is an explanatory diagram illustrating a third example of transaction data according to the embodiment. [Figure 10] FIG. 10 is an explanatory diagram illustrating a fourth example of transaction data in the embodiment. [Figure 11] FIG. 11 is an explanatory diagram illustrating a fifth example of transaction data in the embodiment. [Figure 12] FIG. 12 is a flowchart showing processing of a terminal in the modified example of the embodiment. [Figure 13] FIG. 13 is an explanatory diagram of a first example of transaction data in the modified example of the embodiment. [Figure 14] FIG. 14 is an explanatory diagram illustrating a second example of transaction data in the modification of the embodiment. [Figure 15] FIG. 15 is an explanatory diagram illustrating a third example of transaction data in the modification of the embodiment. [Figure 16] FIG. 16 is an explanatory diagram illustrating a fourth example of transaction data in the modification of the embodiment. [Figure 17] FIG. 17 is an explanatory diagram showing the data structure of a blockchain. [Figure 18] FIG. 18 is an explanatory diagram showing the data structure of the transaction data. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Findings on which the present invention is based) The present inventors have found that the content providing technology described in the "Background Art" section has the following problems.

[0011] Conventionally, there is a content providing technology that utilizes short-distance wireless communication (also called "passing communication") between terminals that move with a user. When providing content, the content provided is the content that the provider has prepared in advance with the intention of providing it.

[0012] Conventionally, there is no known technology for setting conditions (also called provision conditions) for the provision of content. Provision conditions are used, for example, to permit the provision of content if the provision conditions are met, or in other words, to not permit the provision of content if the provision conditions are not met. In other words, provision conditions are sufficient conditions for transmitting and receiving content. Provision conditions are, for example, conditions that stipulate the price for the provision of content.

[0013] In other words, there is no known technology for providing content in such a manner that the user provides the content only if the compensation to be obtained for providing the content is equal to or greater than the user's desire.

[0014] If content could be provided in this manner, it would be possible to provide content more flexibly, and this would have the advantage of further promoting content distribution.

[0015] Thus, conventionally, there is a problem in that it is difficult to reflect the conditions of content provision that the user accepts when providing content.

[0016] Therefore, the present invention provides a control method that can reflect the conditions of provision that a user accepts when providing content.

[0017] In order to solve such problems, a control method according to one embodiment of the present invention is a control method executed by a first device used by a first user in a distributed ledger system having a plurality of devices each holding a distributed ledger that manages the owner of content, the control method transmitting, via short-range wireless communication, to a second device used by a second user among the plurality of devices, identification information of a smart contract including a process of providing the content in accordance with the provision conditions of the content permitted by the first user, receiving, via short-range wireless communication, transaction data including the identification information of the second device and instruction information for instructing the execution of the smart contract, storing the received transaction data in the distributed ledger, and executing the smart contract, thereby changing the owner of the content from the first user to the second user.

[0018] According to the above aspect, the distributed ledger system changes the owner of the content from the first user to the second user according to the provision conditions permitted by the first user, using short-range wireless communication between the first device and the second device. Here, since short-range wireless communication between the first device and the second device is used, the content can be provided from the first user to the second user who is located at a distance where short-range wireless communication is possible. In addition, since the owner is changed by executing a smart contract that reflects the provision conditions permitted by the first user, the change in the owner (i.e., the provision of the content) can be made to reflect the provision conditions permitted by the first user. In this way, according to the above control method, the content can be provided based on the StreetPass communication while reflecting the provision conditions permitted by the user.

[0019] For example, the smart contract may further include a process of generating a password, transmitting the generated password to the second device via short-range wireless communication, the received transaction data being the transaction data transmitted by the second device including the password, and comparing the transmitted password with the password contained in the received transaction data, and providing the content if the comparison is successful.

[0020] According to the above aspect, the distributed ledger system checks a password generated by the system itself against a password sent by the second device to confirm that the second device is sending information based on information received from the first device, and then changes the owner of the content from the first user to the second user. This makes it possible to prevent an unauthorized device imitating the second device from receiving content from the first device. Therefore, the above control method can provide content based on StreetPass communication more appropriately while reflecting the provision conditions permitted by the user.

[0021] For example, the smart contract may include a procedure that prohibits the smart contract from being executed a second time.

[0022] According to the above aspect, the distributed ledger system can prevent unauthorized execution of a process for changing the owner of content. For example, when changing the owner of content based on password matching, the password is included in transaction data and stored in the distributed ledger, and can be referenced. In this case, an unauthorized device can use the password to successfully match the password, but the above control method can prevent the password from succeeding. Therefore, the above control method can provide content based on StreetPass communication more appropriately while reflecting the conditions for providing that the user accepts.

[0023] For example, the conditions for providing the content may include value information regarding the price for providing the content.

[0024] According to the above aspect, the provision conditions include conditions that the first user accepts regarding a fee for the provision of the content. Thus, the above control method can provide the content based on the Passing Communication while further reflecting the conditions regarding the fee that the user accepts.

[0025] For example, the distributed ledger may further manage the transfer of value information between users of each of the multiple devices, and the smart contract may include a process of (a) determining whether the second user holds value information equivalent to compensation for the provision of the content, and (b) providing the content and transferring the value information from the second user to the first user when it is determined that the second user holds the value information.

[0026] According to the above aspect, the distributed ledger system can manage the provision of content from the first user to the second user as well as the provision of compensation from the second user to the first user. Therefore, according to the above control method, content and compensation can be provided based on StreetPass Communication while reflecting the provision conditions permitted by the user.

[0027] For example, the content may be a virtual object in a game.

[0028] According to the above aspect, the distributed ledger system can provide virtual objects based on StreetPass communication while reflecting the provision conditions acceptable to the user.

[0029] For example, the value information may be a virtual currency.

[0030] According to the above aspect, the distributed ledger system can provide content based on StreetPass communication and provide virtual currency in exchange for that content, while reflecting the provision conditions acceptable to the user.

[0031] In addition, a control device according to one embodiment of the present invention is a control device that is a first device used by a first user among a plurality of devices in a distributed ledger system having a plurality of devices that hold a distributed ledger that manages owners of content, and that includes a processor and a memory connected to the processor, wherein the processor uses the memory to transmit, via short-range wireless communication, to a second device among the plurality of devices used by a second user, identification information of a smart contract that includes a process of providing the content in accordance with conditions for providing the content permitted by the first user, receive, via short-range wireless communication, transaction data that includes identification information of the second device and instruction information that instructs execution of the smart contract, stores the received transaction data in the distributed ledger, and executes the smart contract, thereby changing the owner of the content from the first user to the second user.

[0032] According to the above aspect, the same effects as those of the above control method are achieved.

[0033] A program according to one aspect of the present invention is a program for causing a computer to execute the above-described control method.

[0034] According to the above aspect, the same effects as those of the above control method are achieved.

[0035] These comprehensive or specific aspects may be realized as a system, an apparatus, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be realized as any combination of a system, an apparatus, an integrated circuit, a computer program, or a recording medium.

[0036] Hereinafter, the embodiment will be specifically described with reference to the drawings.

[0037] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component arrangement and connection forms, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, among the components in the following embodiments, components that are not described in an independent claim showing a top concept are described as optional components.

[0038] (Embodiment) In this embodiment, a control method that can provide content based on the Passing Communication while reflecting the conditions for providing content that the user accepts will be described.

[0039] FIG. 1 is a block diagram showing a schematic configuration of a management system 1 according to the present embodiment.

[0040] 1, the management system 1 includes terminals 10A, 10B, and 10C (also referred to as terminals 10A, etc.). Each of the terminals 10A, etc. is connected to a network N and can communicate with each other through the network N.

[0041] The management system 1 is a distributed ledger system including a plurality of terminals 10A, which are a plurality of devices that hold a distributed ledger. The distributed ledger manages the owner of the content. Transaction data stored in the distributed ledger includes information indicating the owner of the content. An example of the content is a virtual object in a game (more specifically, a character in a game). The content is not particularly limited as long as it is electronic content, and may be software, text, images, music, or the like, or may be information linked to an entity and indicating the ownership of the entity. The content itself may be managed in the distributed ledger, may be managed in a storage unit (not shown) of the terminal of the content owner, or may be managed in a server (not shown). The content may be managed as an NFT (Non-Fungible Token).

[0042] The distributed ledger can also manage the transfer of value information. In this case, the transaction data stored in the distributed ledger includes information indicating the transfer of value information. The value information can be managed as a Fungible Token (FT). An example of value information is virtual currency (also called a coin).

[0043] When the content is a virtual object in a game and the value information is virtual currency, the management system 1 can be said to be a system that manages transactions of virtual objects in a game in exchange for the virtual currency.

[0044] The terminal 10A is one of the multiple terminals 10A etc. that hold a distributed ledger in the management system 1. Transaction data is stored in the distributed ledger held by the terminal 10A. The terminals 10A etc. can process the provision of content and the provision of consideration by storing transaction data in the distributed ledger and executing a smart contract. The user of the terminal 10A is also referred to as user U.

[0045] The terminals 10B and 10C are devices having the same functions as the terminal 10A, and operate independently of the terminal 10A. The user of the terminal 10B is also called a user V, and the user of the terminal 10C is also called a user W.

[0046] Each of the terminals 10A, etc. is one of the nodes that make up the distributed ledger network. In the distributed ledger network, each of the terminals 10A, etc. is uniquely identified by an address. In addition, each of the smart contracts executed by the terminals 10A, etc. is also uniquely identified by an address in the distributed ledger network.

[0047] When terminals 10A, 10B, and 10C, and smart contract A send and receive information on the distributed ledger network, the addresses of terminals 10A, 10B, and 10C, and the address of smart contract A, respectively, are used.

[0048] In the present embodiment, an example will be described in which the management system 1 includes three terminals 10A, but the management system 1 may include more terminals.

[0049] Network N may be composed of any communication line or network, and may include, for example, the Internet, a mobile phone carrier network, an Internet provider's access network, or a public access network.

[0050] FIG. 2 is an explanatory diagram that illustrates the provision of content in the management system 1 according to the present embodiment.

[0051] Here, a case will be described in which a user U has the intention to provide content, and a user V has the intention to receive the content.

[0052] A user U is moving around with a terminal 10A. A user V is moving around with a terminal 10B.

[0053] When terminals 10A and 10B are carried by users U and V and are moving, respectively, and terminals 10A and 10B are located within a distance where short-distance wireless communication is possible, terminals 10A and 10B transmit and receive information related to the provision of content by short-distance wireless communication. In this way, content is provided from user U to user V. At this time, a fee for the provision of the content may be provided from user V to user U.

[0054] Content is provided by storing transaction data for changing the owner of the content in a distributed ledger that manages the owner of the content. In addition, the content itself may be provided from user U to user V. If the content is managed in the terminal of user U, the content itself is provided from the terminal of user U to the terminal of user V. Furthermore, the payment for the content is provided by storing transaction data indicating the transfer of value information in a distributed ledger that manages the transfer of value information.

[0055] In the following, a case will be described as an example in which content is provided from user U to user V based on short-distance wireless communication between terminal 10A and terminal 10B as shown in FIG.

[0056] The terminal 10A is also referred to as a first device, the terminal 10B is also referred to as a second device, the user U is also referred to as a first user, and the user V is also referred to as a second user.

[0057] First, the functions of the terminal 10A will be described in more detail.

[0058] FIG. 3 is a block diagram showing a schematic configuration of terminal 10A in this embodiment.

[0059] As shown in FIG. 3, the terminal 10A includes a communication unit 11, a short-range communication unit 12, a processing unit 13, an execution unit 14, and a ledger storage unit 15.

[0060] The communication unit 11 is a communication interface that is communicatively connected to the network N. The communication unit 11 has a communication interface of a communication standard appropriate for connecting to the network N. The communication unit 11 may include a communication circuit that transmits and receives a communication signal according to the communication standard, and a communication connector or a communication antenna.

[0061] The short-range communication unit 12 is a communication interface that connects with a terminal located at a relatively close physical distance by wireless communication. The communication standard for wireless communication used by the short-range communication unit 12 is, for example, Bluetooth (registered trademark), Wi-Fi (registered trademark), or IrDA (registered trademark) (Infrared Data Association), but is not limited thereto.

[0062] The short-range communication unit 12 repeatedly transmits a predetermined communication signal (for example, a beacon signal) in accordance with a communication standard to surrounding devices.

[0063] When terminal 10A and terminal 10B are located within a distance where short-range wireless communication is possible, short-range communication unit 12 detects that short-range wireless communication between terminal 10A and terminal 10B is possible by receiving a predetermined communication signal (e.g., a beacon signal) corresponding to a communication standard from terminal 10B, and performs short-range wireless communication between terminal 10A and terminal 10B.

[0064] The processing unit 13 is a functional unit that executes processes such as providing content. The processing unit 13 can be realized by a processor (e.g., a CPU (Central Processing Unit)) included in the terminal 10A executing a program using a memory. The processing unit 13 also executes processes related to transaction data and processes related to smart contracts.

[0065] The processing unit 13 generates a contract code of a smart contract (also called smart contract A) including a process of providing content according to the content provision conditions permitted by the user U. The processing unit 13 stores the generated contract code in the distributed ledger of each of the terminals 10A, etc. The content provision conditions may include value information regarding the price for providing the content.

[0066] When short-range wireless communication between terminal 10A and terminal 10B is possible, processing unit 13 transmits identification information of smart contract A (specifically, the contract address of smart contract A) to terminal 10B by short-range wireless communication. When terminal 10B receives the identification information, it transmits transaction data (also referred to as transaction data B) including the identification information of terminal 10B and instruction information for instructing the execution of smart contract A, in order to receive content. Processing unit 13 receives transaction data B.

[0067] The processing unit 13 receives the transaction data B transmitted by the terminal 10B. The processing unit 13 stores the received transaction data B in the distributed ledger, and executes the smart contract A to perform a process of providing the content.

[0068] When storing transaction data in the distributed ledger, the processing unit 13 stores the transaction data in the distributed ledger in a manner according to the type of the distributed ledger. The processing unit 13 also transmits and receives communication data to and from processing units 13 provided in other terminals among the terminals 10A, etc., via the communication unit 11, and stores the transaction data in the ledger storage unit 15 provided in the other terminals. For example, when the distributed ledger is a blockchain, the processing unit 13 generates a block including new transaction data, and stores the block in the ledger storage unit 15 after reaching a consensus on the generated block among the terminals 10A, etc., using a consensus algorithm.

[0069] The execution unit 14 is a functional unit that executes a smart contract. The execution unit 14 can be realized by a processor (for example, a central processing unit (CPU)) included in the terminal 10A executing a program using a memory.

[0070] Specifically, based on the processing unit 13 storing transaction data including instruction information instructing the execution of smart contract A in the distributed ledger, the execution unit 14 reads the contract code of smart contract A from the ledger storage unit 15 and executes smart contract A. By executing smart contract A, the execution unit 14 changes the owner of the content from user U to user V.

[0071] The ledger storage unit 15 is a storage unit that stores the distributed ledger. The distributed ledger stored in the ledger storage unit 15 stores one or more transaction data, and is managed to make tampering difficult using characteristics such as hash values ​​(described later). The ledger storage unit 15 stores the transaction data provided by the processing unit 13 in the distributed ledger. The distributed ledger stores transaction data from the past to the present. Based on the characteristic that information recorded in the distributed ledger is difficult to tamper with, the transaction data is managed to prevent tampering.

[0072] The distributed ledger is, for example, a blockchain, and this case will be described as an example, but other types of distributed ledgers (for example, IOTA or hash graph) can also be adopted. The distributed ledger may or may not execute a consensus algorithm (for example, Practical Byzantine Fault Tolerance (PBFT), Proof of Work (PoW), or Proof of Stake (PoS)) when storing new data. Hyperledger fabric is an example of a distributed ledger technology that does not execute a consensus algorithm.

[0073] Next, the functionality of the terminal 10B will be described in more detail.

[0074] Similar to the terminal 10A, the terminal 10B includes a communication unit 11, a short-range communication unit 12, a processing unit 13, an execution unit 14, and a ledger storage unit 15.

[0075] Among the components included in the terminal 10B, the components other than the processing unit 13 are the same as the components having the same names in the terminal 10A.

[0076] The processing unit 13 is a functional unit that executes processes such as providing content. The processing unit 13 can be realized by a processor (e.g., a CPU) included in the terminal 10B executing a program using a memory. The processing unit 13 also executes processes related to transaction data and processes related to smart contracts.

[0077] The processing unit 13 receives the identification information of smart contract A transmitted from the processing unit 13 of the terminal 10A by short-range wireless communication. The processing unit 13 acquires the content provision conditions indicated in the smart contract A based on the received identification information, and decides whether or not to accept the provision of the content according to the acquired provision conditions. The above decision may be made by the judgment of the user V, or may be made by the processing unit 13 based on predetermined information. The acquired provision conditions may be displayed on the display of the terminal of the user V. The user V inputs whether or not to accept the provision of the content by performing an operation corresponding to whether or not he or she agrees to the provision conditions displayed on the display.

[0078] When it is decided to receive the provision of the content, the processing unit 13 transmits transaction data B including identification information of the terminal 10B and instruction information for instructing the execution of the smart contract A.

[0079] In the above, the functions of terminal 10A and the functions of terminal 10B have been described separately, but each of terminal 10A and terminal 10B may be a terminal having both the functions of terminal 10A and the functions of terminal 10B described above.

[0080] In the management system 1, the terminal 10A may process the provision of content after confirming that the terminal 10B is indeed sending information based on the information received from the terminal 10A. A password may be used for the above confirmation. In this case, the processing unit 13 of the terminal 10A includes a conditional expression used for password matching in the smart contract A. For example, the conditional expression that the password must satisfy may be expressed as f(a)=P, where a is the password. Also, f(a) is a function with a variable a, for example a hash function.

[0081] The processing unit 13 of the terminal 10A generates a password in advance, and calculates P by substituting the generated password into the function f(a). The processing unit 13 of the terminal 10A includes the function f(a) and the calculated P in the smart contract A and stores them in the distributed ledger.

[0082] When short-range wireless communication between terminal 10A and terminal 10B is possible, processing unit 13 of terminal 10A transmits a pre-generated password to terminal 10B via short-range wireless communication. Terminal 10B transmits transaction data B including the received password to terminal 10A. In this case, smart contract A may include a process of comparing the password transmitted by processing unit 13 of terminal 10A with the password included in the received transaction data B, and providing content if the comparison is successful.

[0083] Furthermore, smart contract A may include a process for prohibiting smart contract A from being executed a second time. The above process may be realized, for example, by using a variable (e.g., a flag variable) indicating whether execution of smart contract A is permitted. Specifically, the above variable may be initially set to a value (e.g., 0) corresponding to execution of smart contract A being permitted, and then changed in smart contract A to a value (e.g., 1) corresponding to execution not being permitted (i.e., execution being prohibited).

[0084] The reason why smart contract A is prohibited from being executed a second time is to prevent unauthorized password matching from succeeding. After transaction data including a password is stored in the distributed ledger, all terminals 10A, etc. and all users can refer to the password, and therefore a terminal or user who has referred to the password can successfully match the password. In this way, in the management system 1, smart contract A can be executed only once, and the password can be used only once. For this reason, the password may also be called a one-time password.

[0085] In addition, when the distributed ledger provided in the management system 1 manages the transfer of value information between users of multiple terminals 10A, etc., smart contract A may include a process of (a) determining whether or not user V holds value information equivalent to the compensation for the provision of content, and (b) providing the content and transferring the value information from user V to user U when it is determined that user V holds the value information.

[0086] If a person who wishes to provide content is not the owner of the content, or if a payment is required to receive the content but the person who wishes to receive the content does not have value information equivalent to the payment, a penalty may be imposed on that person. The imposition of a penalty can be performed by storing transaction data for imposing the penalty in the distributed ledger.

[0087] The processing of the management system 1 will be described in more detail below.

[0088] Here, an example will be described in which a password is used when providing content, and a payment must also be provided when providing the content.

[0089] Fig. 4 is a first sequence diagram showing the processing of the management system 1 in this embodiment. Fig. 4 shows processing executed before the terminal 10A performs short-range wireless communication with the terminal 10B, which is processing for storing the contract code of the smart contract A in the distributed ledger (also generally referred to as a deploy processing).

[0090] In step S101, the terminal 10A generates a password.

[0091] In step S102, the terminal 10A generates a contract code for smart contract A.

[0092] In step S103, the terminal 10A generates transaction data A including the contract code generated in step S102, and transmits the generated transaction data A to the other terminals 10B and 10C. The terminals 10B and 10C receive the transaction data.

[0093] In step S104, terminal 10A stores the transaction data generated in step S103 in the distributed ledger. Terminals 10B and 10C also store the transaction data received in step S103 in the distributed ledger. When storing the transaction data in the distributed ledger, terminals 10A and the like may store the transaction data in the distributed ledger on the condition that a consensus has been reached based on a consensus algorithm. The same applies when storing subsequent transaction data (transaction data B to J) in the distributed ledger.

[0094] Through the series of processes shown in Figure 4, the contract code of smart contract A can be stored in the distributed ledger.

[0095] Fig. 5 is a second sequence diagram showing the processing of the management system 1 in this embodiment. Fig. 6 is a flow diagram showing the processing of the terminal 10A in this embodiment.

[0096] 5 and 6, a process in which the terminal 10A etc. executes the smart contract A based on the terminal 10A performing short-range wireless communication with the terminal 10B is shown.

[0097] In step S201, the terminal 10A determines whether short-distance wireless communication with another terminal is possible. If it is determined that short-distance wireless communication with another terminal is possible (Yes in step S201), the process proceeds to step S202, and if not (No in step S201), step S201 is executed again. That is, the terminal 10A waits in step S201 until short-distance wireless communication with another terminal is possible.

[0098] Here, it is assumed that in step S201, terminal 10A is able to perform short-distance wireless communication with terminal 10B, which is an example of another terminal.

[0099] In step S202, the terminal 10A transmits the contract address of the smart contract A to the terminal 10B by short-range wireless communication. The terminal 10B receives the transmitted contract address.

[0100] In step S203, the terminal 10B refers to the content provision conditions indicated in the smart contract A using the received contract address based on the contract address received in step S202. Then, when the terminal 10B decides to receive the content according to the provision conditions, it transmits a content provision request to the terminal 10A. The terminal 10A receives the transmitted provision request.

[0101] In step S204, based on the receipt of the provision request in step S203, the terminal 10A transmits the password to the terminal 10B. The password to be transmitted is the password generated in step S101. The terminal 10B receives the transmitted password.

[0102] In step S205, based on the password received in step S204, the terminal 10B generates transaction data (also referred to as transaction data B) including instruction information for instructing the execution of smart contract A and the received password, and transmits the transaction data to the other terminals 10A and 10C. The other terminals 10A and 10C receive the transmitted transaction data B.

[0103] In step S206, terminal 10B stores transaction data B generated in step S205 in the distributed ledger. Also, terminals 10A and 10C store transaction data B received in step S205 in the distributed ledger.

[0104] In step S207, the execution unit 14 of each of the terminals 10A, etc. executes the smart contract A based on the storage of the transaction data B in the distributed ledger in step S206. The process performed by the execution of the smart contract A will be described in detail with reference to FIG.

[0105] As shown in Fig. 6, in step S301, the execution unit 14 determines whether or not the execution of the smart contract A is permitted. If it is determined that the execution is permitted (Yes in step S301), the process proceeds to step S302, and if not (No in step S301), the series of processes shown in Fig. 6 is terminated. Note that when step S301 is executed for the first time, it is assumed that the execution of the smart contract A is permitted (for example, the flag variable is 0).

[0106] In step S302, the execution unit 14 performs a process of comparing the password transmitted by the terminal 10A in step S204 with the password included in the transaction data B generated in step S205, and determines whether the comparison is successful or not. If it is determined that the comparison is successful (Yes in step S302), the process proceeds to step S303, and if not (No in step S302), the process proceeds to step S321.

[0107] In step S303, the execution unit 14 determines whether the owner of the content is user U. Specifically, the execution unit 14 refers to the distributed ledger and determines whether it is recorded in the distributed ledger that the owner of the content is user U. If it is determined that the owner of the content is user U (Yes in step S303), the process proceeds to step S304, and if not (No in step S303), the process proceeds to step S311.

[0108] In step S304, the execution unit 14 determines whether or not the user V holds an amount of coins equivalent to the compensation for the provision of the content. Specifically, the execution unit 14 refers to the distributed ledger and determines whether or not the amount of coins held by the user V is greater than the amount of coins equivalent to the compensation for the provision of the content. If it is determined that the user V holds an amount of coins equivalent to the compensation for the provision of the content (Yes in step S304), the process proceeds to step S305, and if not (No in step S304), the process proceeds to step S321.

[0109] In step S305, the execution unit 14 generates transaction data (also referred to as transaction data C) for changing the owner of the content from user U to user V, and transmits the generated transaction data C to the other terminals 10B and 10C. The terminals 10B and 10C receive the transmitted transaction data C.

[0110] In step S306, the execution unit 14 stores the transaction data C generated in step S305 in the distributed ledger. Also, the terminals 10B and 10C store the transaction data C received in step S305 in the distributed ledger.

[0111] In step S307, the execution unit 14 generates transaction data (also referred to as transaction data D) for transferring an amount of coins equivalent to the compensation for the provision of the content from user V to user U, and transmits the generated transaction data D to the other terminals 10B and 10C. The terminals 10B and 10C receive the transmitted transaction data D.

[0112] In step S308, the execution unit 14 stores the transaction data D generated in step S307 in the distributed ledger. Also, the terminals 10B and 10C store the transaction data D received in step S307 in the distributed ledger.

[0113] In step S309, the execution unit 14 performs control so that the execution of the smart contract A is not permitted (for example, the flag variable is changed to 1). By the above control, the smart contract A is not permitted to be executed from this point onwards (i.e., execution is prohibited).

[0114] In step S311, the execution unit 14 generates transaction data (also referred to as transaction data E) for assigning a penalty to the user U, and transmits the generated transaction data E to the other terminals 10B and 10C. The terminals 10B and 10C receive the transmitted transaction data E.

[0115] In step S312, the execution unit 14 stores the transaction data E generated in step S311 in the distributed ledger. Also, the terminals 10B and 10C store the transaction data E received in step S311 in the distributed ledger.

[0116] In step S321, the execution unit 14 generates transaction data (also referred to as transaction data F) for assigning a penalty to the user V, and transmits the generated transaction data F to the other terminals 10B and 10C. The terminals 10B and 10C receive the transmitted transaction data F.

[0117] In step S322, the execution unit 14 stores the transaction data F generated in step S321 in the distributed ledger. Also, the terminals 10B and 10C store the transaction data F received in step S321 in the distributed ledger.

[0118] When step S309, S312 or S322 is completed, the series of processes shown in FIG. 6 ends.

[0119] If no password is used, step S204 is not performed, and the transaction data B generated by terminal 10B in step S205 does not include a password.

[0120] Similarly to terminal 10A, terminals 10B and 10C also execute the series of processes shown in FIG. 6 by executing smart contract A.

[0121] Through the series of processes shown in FIGS. 5 and 6, smart contract A can be executed based on short-range wireless communication between terminal 10A and terminal 10B.

[0122] Next, the transaction data used by the management system 1 will be described.

[0123] 7 is an explanatory diagram showing transaction data A, which is a first example of transaction data in this embodiment. The transaction data A is used in the deployment process of smart contract A (see FIG. 4).

[0124] As shown in FIG. 7, transaction data A includes a contract code and a signature.

[0125] The contract code is the contract code of smart contract A, and at least a process for providing content is described. The contract code is written using a language for writing smart contracts (for example, the Solidity language or the Vyper language).

[0126] The signature includes the digital signature (ie, SU) of user U, who is the user of the terminal that generated the transaction data A (ie, terminal 10A).

[0127] 8 is an explanatory diagram showing a second example of transaction data B in this embodiment. The transaction data B includes instruction information for instructing the execution of the smart contract A.

[0128] As shown in FIG. 8, transaction data B includes a source address, a destination address, a password, content identification information, payment information, and a signature.

[0129] The source address is the address of the terminal that is the source of the transaction data B, and specifically includes the address of the terminal 10B.

[0130] The destination address is the address of the smart contract whose execution is instructed by the transaction data B, and specifically, the address of smart contract A is set thereto. The destination address in which the address of smart contract A is set corresponds to instruction information instructing the execution of smart contract A.

[0131] The password is the password that terminal 10B received from terminal 10A (steps S204, S205).

[0132] The content identification information is information that can uniquely identify the content requested by the transaction data B.

[0133] The consideration information is value information to be provided as consideration for the provision of content when the provision of content is requested by the transaction data B, and is, for example, an amount of coins equivalent to the consideration.

[0134] The signature includes the digital signature (ie, SV) of user V, who is the user of the terminal that generated the transaction data B (ie, terminal 10B).

[0135] 9 is an explanatory diagram showing a third example of transaction data C according to the present embodiment. The transaction data C is used as information indicating a change in the owner of the content.

[0136] As shown in FIG. 9, the transaction data C includes the pre-transfer owner, the post-transfer owner, the identification information of the content, and a signature.

[0137] The previous owner is identification information that can uniquely identify the owner of the content before it is transferred, and specifically includes the identification information of the user U.

[0138] The post-transfer owner is identification information that can uniquely identify the owner of the content after the transfer, and specifically includes the identification information of user V.

[0139] The content identification information is information that can uniquely identify the content whose owner is changed by the transaction data C.

[0140] The signature includes the digital signature (ie, SU) of user U, who is the user of the terminal that generated the transaction data C (ie, terminal 10A).

[0141] 10 is an explanatory diagram showing a fourth example of transaction data in this embodiment, that is, transaction data D. Transaction data D is used as information indicating the provision of a consideration.

[0142] As shown in FIG. 10, transaction data D includes a provider, an acquirer, consideration information, and a signature.

[0143] The provider is identification information that can uniquely identify the user who provides the consideration, and specifically includes the identification information of user V.

[0144] The acquirer is identification information that can uniquely identify the user who acquires the consideration, and specifically includes the identification information of the user U.

[0145] The compensation information is information that indicates the amount of compensation for the provision of the content.

[0146] The signature includes the digital signature (ie, SU) of user U, who is the user of the terminal that generated the transaction data D (ie, terminal 10A).

[0147] 11 is an explanatory diagram showing a fifth example of transaction data in this embodiment, that is, transaction data E or F. Transaction data E or F is used as information indicating the imposition of a penalty.

[0148] As shown in FIG. 11, transaction data E or F includes the person to whom the penalty is to be imposed, penalty information, and a signature.

[0149] The person to whom a penalty is given is identification information that can uniquely identify the user to whom a penalty is given. In transaction data E, the person to whom a penalty is given includes identification information of user U. In transaction data F, the person to whom a penalty is given includes identification information of user V.

[0150] The penalty information is information indicating the content of the penalty given to the person who is given the penalty. For example, the penalty information is information indicating the magnitude of the penalty in numerical form. For example, the penalty information is information on the number of coins that the person who is given the penalty must pay.

[0151] The signature includes the digital signature (ie, SU) of user U, who is the user of the terminal that generated the transaction data E or F (ie, terminal 10A).

[0152] As described above, the management system 1 of the present embodiment can provide content based on the Passing Communication while reflecting the conditions for providing content permitted by the user.

[0153] In this embodiment, the terminal 10A, which is a device that provides content, generates the contract code of the smart contract A indicating the provision conditions (see step S102 in FIG. 4), but instead, the terminal 10B, which is a device that receives the provision of content, may generate the contract code of the smart contract indicating the provision conditions for receiving the provision of content. In that case, the terminal 10B generates transaction data including the generated contract code, and stores the generated transaction data in the distributed ledger of each of the terminals 10A, etc.

[0154] (Modification of the embodiment) In this modification, another example of the process (see FIG. 6) performed by the terminal 10A by executing the smart contract A will be described.

[0155] In this modification, the process of changing the owner of the content in the above embodiment and the process of transferring the amount of coins equivalent to the compensation (i.e., the process within the dashed box SA in FIG. 6) are executed by a smart contract.

[0156] 12 is a flow diagram showing the process of the terminal 10A in this modified example. The process shown in FIG. 12 is another example of the process within the dashed line frame SA in FIG.

[0157] In step S401, the execution unit 14 generates a contract code of a smart contract (also called smart contract B) for changing the owner of the content from user U to user V.

[0158] In step S402, the execution unit 14 generates transaction data (also referred to as transaction data G) including the contract code of the smart contract B generated in step S401, and transmits the generated transaction data G to the other terminals 10B and 10C. The terminals 10B and 10C receive the transmitted transaction data G.

[0159] In step S403, the execution unit 14 stores the transaction data G generated in step S402 in the distributed ledger. Also, the terminals 10B and 10C store the transaction data G received in step S402 in the distributed ledger.

[0160] Note that steps S401 to S403 correspond to the deployment process of smart contract B.

[0161] In step S404, the execution unit 14 generates transaction data (also referred to as transaction data H) including instruction information instructing the execution of smart contract B, and transmits the generated transaction data H to the other terminals 10B and 10C. The terminals 10B and 10C receive the transmitted transaction data H.

[0162] In step S405, the execution unit 14 stores the transaction data H generated in step S404 in the distributed ledger. Also, the terminals 10B and 10C store the transaction data H received in step S404 in the distributed ledger.

[0163] In step S406, the execution unit 14 of each of the terminals 10A, etc. executes smart contract B based on storing the transaction data H in the distributed ledger in step S405. Since smart contract B describes a process for changing the owner of the content from user U to user V, the execution unit 14 executes smart contract B to change the owner of the content from user U to user V.

[0164] In step S411, the execution unit 14 generates a contract code of a smart contract (also called smart contract C) for transferring an amount of coins equivalent to the compensation for the provision of the content from user V to user U.

[0165] In step S412, the execution unit 14 generates transaction data (also referred to as transaction data I) including the contract code of the smart contract C generated in step S411, and transmits the generated transaction data I to the other terminals 10B and 10C. The terminals 10B and 10C receive the transmitted transaction data I.

[0166] In step S413, the execution unit 14 stores the transaction data I generated in step S412 in the distributed ledger. Also, the terminals 10B and 10C store the transaction data I received in step S412 in the distributed ledger.

[0167] Note that steps S411 to S413 correspond to the deployment process of smart contract C.

[0168] In step S414, the execution unit 14 generates transaction data (also referred to as transaction data J) including instruction information instructing the execution of the smart contract C, and transmits the generated transaction data J to the other terminals 10B and 10C. The terminals 10B and 10C receive the transmitted transaction data J.

[0169] In step S415, the execution unit 14 stores the transaction data J generated in step S414 in the distributed ledger. Also, the terminals 10B and 10C store the transaction data J received in step S414 in the distributed ledger.

[0170] In step S416, the execution unit 14 of each of the terminals 10A, etc. executes the smart contract C based on storing the transaction data J in the distributed ledger in step S415. Since the smart contract C describes a process for transferring an amount of coins equivalent to the consideration for the provision of the content from user V to user U, the execution unit 14 executes the smart contract C to transfer an amount of coins equivalent to the consideration for the provision of the content from user V to user U.

[0171] Next, the transaction data used by the management system 1 in this modified example will be described.

[0172] 13 is an explanatory diagram showing a first example of transaction data in this modified example, transaction data G. The transaction data G is used in the deployment process of smart contract B (see steps S401 to S403 in FIG. 12).

[0173] As shown in FIG. 13, the transaction data G includes a contract code and a signature.

[0174] The contract code is the contract code of smart contract B, and at least a process for providing content is described. The contract code is written using a language for writing smart contracts (for example, the Solidity language or the Go language).

[0175] The signature includes the digital signature (ie, SU) of user U, who is the user of the terminal that generated the transaction data A (ie, terminal 10A).

[0176] 14 is an explanatory diagram showing a second example of transaction data in this modification, that is, transaction data H. The transaction data H is used as instruction information for instructing the execution of smart contract B.

[0177] As shown in FIG. 14, the transaction data H includes a source address, a destination address, and a signature.

[0178] The source address is the address of the terminal that is the source of the transaction data H, and specifically includes the address of terminal 10A.

[0179] The destination address is the address of the smart contract whose execution is instructed by the transaction data H, and specifically includes the address of smart contract B.

[0180] The signature includes the digital signature (ie, SU) of user U, who is the user of the terminal that generated the transaction data H (ie, terminal 10A).

[0181] 15 is an explanatory diagram showing a third example of transaction data I in this modified example. The transaction data I is used in the deployment process of the smart contract C (see steps S411 to S413 in FIG. 12).

[0182] As shown in FIG. 15, the transaction data I includes a contract code and a signature.

[0183] The contract code is the contract code of the smart contract C, and at least a process for providing content is described. The contract code is written using a language for writing smart contracts (for example, the Solidity language or the Go language).

[0184] The signature includes the digital signature (ie, SU) of user U, who is the user of the terminal that generated the transaction data A (ie, terminal 10A).

[0185] 16 is an explanatory diagram showing a fourth example of transaction data in this modification, that is, transaction data J. The transaction data J is used as instruction information for instructing the execution of smart contract C.

[0186] As shown in FIG. 16, transaction data J includes a source address, a destination address, and a signature.

[0187] The source address is the address of the terminal that is the source of the transaction data I, and specifically includes the address of terminal 10A.

[0188] The destination address is the address of the smart contract whose execution is instructed by the transaction data J, and specifically includes the address of smart contract C.

[0189] The signature includes the digital signature (ie, SU) of user U, who is the user of the terminal that generated the transaction data J (ie, terminal 10A).

[0190] (supplement) The following provides a supplementary explanation of the distributed ledger in the above embodiment or the modified example. Here, a blockchain will be explained as an example of a distributed ledger, but the same applies to other distributed ledgers.

[0191] FIG. 17 is an explanatory diagram showing the data structure of a blockchain.

[0192] A blockchain is a set of blocks, which are units of recording, connected in a chain. Each block contains multiple transaction data and the hash value of the immediately preceding block. Specifically, block B2 contains the hash value of the previous block B1. A hash value calculated from the multiple transaction data contained in block B2 and the hash value of block B1 is included in block B3 as the hash value of block B2. In this way, by connecting blocks in a chain while including the contents of the previous block as a hash value, tampering with the recorded transaction data is effectively prevented.

[0193] If past transaction data is changed, the hash value of the block will be different from the value before the change, and in order to make the altered block appear correct, all blocks after it would have to be recreated, which is practically very difficult. This property is used to ensure that the blockchain is tamper-resistant.

[0194] FIG. 18 is an explanatory diagram showing the data structure of the transaction data.

[0195] 18 includes a transaction body P1 and a digital signature P2. The transaction body P1 is the main data included in the transaction data. The digital signature P2 is generated by signing the hash value of the transaction body P1 with the signature key of the creator of the transaction data, or more specifically, by encrypting it with the private key of the creator.

[0196] The transaction data is virtually impossible to tamper with because it has the digital signature P2, which prevents tampering with the transaction body.

[0197] As described above, according to the control method of the above embodiment or the above modification, the distributed ledger system changes the owner of the content from the first user to the second user according to the provision conditions permitted by the first user using short-range wireless communication between the first device and the second device. Here, since short-range wireless communication between the first device and the second device is used, the content can be provided from the first user to the second user located at a distance where short-range wireless communication is possible. In addition, since the owner is changed by executing a smart contract that reflects the provision conditions permitted by the first user, the change in the owner (i.e., the provision of the content) can be made to reflect the provision conditions permitted by the first user. In this way, according to the above control method, the content can be provided based on the StreetPass communication while reflecting the provision conditions permitted by the user.

[0198] In addition, the distributed ledger system checks a password generated by the device itself against a password sent by the second device to confirm that the second device is sending information based on information received from the first device, and then changes the owner of the content from the first user to the second user. This makes it possible to prevent an unauthorized device imitating the second device from receiving content from the first device. Therefore, the above control method can provide content based on StreetPass communication more appropriately while reflecting the provision conditions permitted by the user.

[0199] Furthermore, the distributed ledger system can prevent unauthorized execution of a process for changing the owner of content. When changing the owner of content based on password matching, the password is included in transaction data and stored in the distributed ledger, and can be referenced. In this case, an unauthorized device can use the password to successfully match the password, but the above control method can prevent the password from succeeding. Therefore, the above control method can provide content based on StreetPass communication more appropriately while reflecting the conditions for providing that the user accepts.

[0200] In addition, the provision conditions include conditions that the first user accepts regarding a fee for the provision of the content. Thus, the control method can provide the content based on the Passing Communication while further reflecting the conditions regarding the fee that the user accepts.

[0201] In addition, the distributed ledger system can manage the provision of content from the first user to the second user as well as the provision of compensation from the second user to the first user. Therefore, according to the above control method, content and compensation can be provided based on StreetPass communication while reflecting the conditions of provision accepted by the user.

[0202] In addition, the distributed ledger system can provide virtual objects based on StreetPass communication while reflecting the conditions of provision acceptable to the user.

[0203] In addition, the distributed ledger system can provide content based on StreetPass communication and provide virtual currency in return, while reflecting the terms of provision acceptable to the user.

[0204] In the above-described embodiments, each component may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory. Here, the software for realizing the content management system of the above-described embodiments is a program such as the following.

[0205] In other words, this program causes a computer to execute a control method in a distributed ledger system having a plurality of devices that hold a distributed ledger that manages the owners of content, the control method being executed by a first device used by a first user among the plurality of devices, the control method transmitting, via short-range wireless communication, to a second device used by a second user among the plurality of devices, identification information of a smart contract that includes a process of providing the content in accordance with the provision conditions of the content permitted by the first user, receiving, via short-range wireless communication, transaction data that includes the identification information of the second device and instruction information that instructs the execution of the smart contract, storing the received transaction data in the distributed ledger, and executing the smart contract, thereby changing the owner of the content from the first user to the second user.

[0206] Although the management system according to one or more aspects has been described based on the embodiment, the present invention is not limited to this embodiment. As long as it does not deviate from the spirit of the present invention, various modifications conceived by a person skilled in the art to this embodiment and forms constructed by combining components in different embodiments may also be included within the scope of one or more aspects. [Industrial Applicability]

[0207] The present invention can be used in a management system that manages the provision of content based on passing communication. [Explanation of symbols]

[0208] 1 Management System 10A, 10B, 10C terminals 11 Communications Department 12 Near Field Communication Department 13 Processing section 14 Executive Department 15 Ledger storage unit B1, B2, B3 Blocks N Network P1 Transaction Body P2 Digital Signature U, V, W Users

Claims

1. A control method for a distributed ledger system having a plurality of devices that holds a distributed ledger that manages owners of content, the method being executed by a first device used by a first user among the plurality of devices, the method comprising: Transmitting, via short-range wireless communication, to a second device used by a second user among the plurality of devices, identification information of a smart contract including a process of providing the content in accordance with a provision condition of the content permitted by the first user; Receiving transaction data via short-range wireless communication, the transaction data including identification information of the second device and instruction information for instructing execution of the smart contract; storing the received transaction data in the distributed ledger and executing the smart contract to change the owner of the content from the first user to the second user; Control methods.

2. Furthermore, a password is generated, and the generated password is transmitted to the second device by short-range wireless communication; the received transaction data is the transaction data transmitted by the second device including a password, The smart contract includes a process of comparing the transmitted password with the password included in the received transaction data, and providing the content if the comparison is successful. The control method according to claim 1 .

3. The smart contract includes a process for prohibiting the smart contract from being executed a second time. The control method according to claim 1 or 2.

4. The conditions for providing the content include value information regarding the price for providing the content. The control method according to any one of claims 1 to 3.

5. The distributed ledger further manages transfer of value information between users of each of the plurality of devices; The smart contract comprises: (a) determining whether the second user has value information corresponding to the compensation for the provision of the content; (b) providing the content and transferring the value information from the second user to the first user when it is determined that the second user holds the value information. The control method according to claim 4.

6. The content is a virtual object in a game. The control method according to any one of claims 1 to 5.

7. The value information is a virtual currency. The control method according to claim 5.

8. A control device is a first device used by a first user among a plurality of devices in a distributed ledger system having a distributed ledger that manages owners of content, A processor and a memory coupled to the processor, The processor uses the memory to: Transmitting, via short-range wireless communication, to a second device used by a second user among the plurality of devices, identification information of a smart contract including a process of providing the content in accordance with a provision condition of the content permitted by the first user; Receiving transaction data via short-range wireless communication, the transaction data including identification information of the second device and instruction information for instructing execution of the smart contract; storing the received transaction data in the distributed ledger and executing the smart contract to change the owner of the content from the first user to the second user; Control device.

9. A program for causing a computer to execute the control method according to any one of claims 1 to 7.

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