Information processing method

Abstract

To provide an information processing method capable of selectively deleting ledgers by node.SOLUTION: A ledger management device processes information relating to multiple nodes 70 by using a blockchain technique. In the information processing method, a delete trigger is set to a ledger 80 that is provided to each node 70. The ledger 80 stores data to be stored, which is associated with each node 70. When the delete trigger is activated, a ledger 80 corresponding to the delete trigger is deleted based on the delete trigger.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] TECHNICAL FIELD This disclosure relates to a method for processing information. [Background technology]

[0002] Patent Document 1 discloses a management device that uses a blockchain, which is an example of a distributed ledger. If such a blockchain is operated for a long period of time, the amount of storage used will be enormous. Therefore, in the management device of Patent Document 1, the distributed ledger is managed in association with the ledger status, and unnecessary distributed ledgers that have reached the ledger status of being no longer in operation are deleted. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-190102 Summary of the Invention [Problem to be solved by the invention]

[0004] The management device of Patent Document 1 only performs centralized ledger management associated with the ledger status. In other words, if a ledger network includes multiple nodes, the ledger status cannot be changed for each node. Therefore, even if one of the multiple nodes wants to continue holding the ledger, it has no choice but to follow the ledger status change made by the management device, and there is a problem in that deletion cannot be avoided.

[0005] The present disclosure aims to provide an information processing method that enables selective deletion of ledgers on a node-by-node basis. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, one aspect disclosed is an information processing method for processing information related to a plurality of nodes (70) using blockchain technology, the information processing method including, in processing executed by at least one processor (11), the steps of setting a deletion trigger (S31) for a ledger (80) that is provided for each node and stores data to be stored linked to each node, activating the deletion trigger (S32), and deleting the ledger corresponding to the deletion trigger based on the activation of the deletion trigger (S33).

[0007] In this embodiment, instead of centralized ledger management, an individual deletion trigger is set for the ledger provided for each node. In this way, by managing the ledger individually for each node, it becomes possible to selectively delete the ledger for each node based on the activation of the deletion trigger.

[0008] In addition, the reference numbers in parentheses in the above and claims merely show an example of the correspondence with the specific configurations in the embodiments described below, and do not limit the technical scope in any way. In addition, claims that are not explicitly stated in the claims can be combined together as long as there is no particular problem with the combination. [Brief description of the drawings]

[0009] [Figure 1] A block diagram showing a ledger management device in which an information processing method according to one embodiment of the present disclosure is executed, together with a ledger network. [Diagram 2] FIG. 13 is a diagram showing details of a ledger generated in a ledger network. [Diagram 3] 10 is a flowchart showing details of a ledger generation process performed by the ledger management device. [Figure 4] 13A and 13B are diagrams illustrating examples of time conditions that are set in a generation trigger and a deletion trigger. [Diagram 5] FIG. 13 illustrates a process for deleting a specific ledger from a ledger network. [Figure 6]13 is a flowchart showing details of a ledger deletion process performed by the ledger management device. [Figure 7] FIG. 13 is a diagram showing a ledger management device etc. of modified example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A ledger management device 100 according to an embodiment of the present disclosure shown in FIG. 1 is applied to a blockchain platform that uses blockchain technology to store information in a manner that makes it difficult to tamper with. A general-purpose blockchain framework such as Hyperledger Fabric is used for the blockchain platform. The ledger management device 100 manages at least one ledger network 60 constructed in the blockchain platform.

[0011] [Overall configuration] First, the details of the ledger network 60 and the ledger management device 100 will be described with reference to FIG.

[0012] The ledger network 60 is interconnected with the ledger management device 100 via a network NW. The network NW may be a public network open to the public, or a private network (such as an intranet) with restricted access from outside, or a combination of these. The ledger network 60 includes one or more nodes 70. When the ledger network 60 includes multiple nodes 70, the nodes 70 are interconnected with each other via the network NW.

[0013] The node 70 is constructed, for example, by a server (virtual machine) on the cloud. The node 70 is mainly configured with a control circuit equipped with a processor, RAM, a storage unit, an input / output interface, and a bus connecting these. The node 70 functions as a high-performance computer that performs calculation processing at high speed. The node 70 is linked to a client system of a participant of the ledger network 60 (hereinafter, a node operator). The client system includes a user terminal connected to the network NW. The node operator or an operator belonging to the node operator can access the ledger network 60 using the user terminal.

[0014] At least one distributed ledger 80 is provided in the node 70. The distributed ledger 80 is a technology for sharing the same data among multiple nodes 70. The distributed ledger 80 is an example of a blockchain. A blockchain is configured by linking multiple blocks in chronological order. In the blockchain, a certain number of transaction data are organized into blocks. Each block holds information that uniquely represents the previous block. The blockchain is recorded in the distributed ledger 80 and is shared by multiple nodes 70 as described above.

[0015] The node 70 can operate multiple ledgers 80. The ledger 80 is generated for each node 70, and stores electronic data linked to the node 70 as data to be stored. Some of the multiple nodes 70 may not have a ledger 80. Data to be stored that is managed by a node operator, for example, transaction records of the node operator, are recorded in the ledger 80.

[0016] The data to be stored and recorded in the ledger 80 includes a data body 81 and auxiliary data 82 (see FIG. 2). The data body 81 is the main data (ledger data) of the ledger 80. The data body 81 is registered as block data (transaction) in one block of the blockchain. The auxiliary data 82 is data related to the data body 81. The auxiliary data 82 is, for example, backup data of the data body 81 or original data used to generate the data body 81.

[0017] In the ledger network 60, information recorded in the ledger 80 is managed in a distributed manner by multiple nodes 70. That is, information stored in the ledger 80 of one node 70 is shared with other nodes 70 belonging to the same ledger network 60. When multiple nodes 70 hold the same information, the reliability and transparency of the information are improved.

[0018] The ledger management device 100 is connected to a terminal used by a system administrator (hereinafter referred to as an administrator terminal) and a user terminal of a node operator via a network NW. The system administrator is an administrator who manages multiple nodes 70 included in the ledger network 60. The system administrator may be different for each ledger network 60, or may be common to all ledger networks 60.

[0019] The ledger management device 100 manages access from the administrator terminal and the user terminal to the ledger network 60. The ledger management device 100 performs authentication and authorization for connections from the administrator terminal and the user terminal to the ledger network 60. Specifically, the ledger management device 100 accepts various operation requests related to the ledger network 60.

[0020] Ledger management device 100 is constructed, for example, by a server on the cloud, similar to node 70. Ledger management device 100 is mainly composed of a processor 11, RAM 12, storage unit 13, input / output interface 14, and a control circuit equipped with a bus connecting these. Ledger management device 100 functions as a high-performance computer that performs calculation processing at high speed.

[0021] The processor 11 is hardware for arithmetic processing coupled to the RAM 12. The processor 11 executes various processes (instructions) related to the management and provision of data by accessing the RAM 12. The memory unit 13 stores an information processing program that realizes functions related to the management of the ledger network 60. The information processing program is a program for causing the ledger management device 100 to carry out the information processing method of the present disclosure. The input / output interface 14 is connected to a communication device or the like that enables communication with the network NW.

[0022] The ledger management device 100 is provided with functional units such as a generation trigger setting unit 21 and a deletion trigger setting unit 22 by executing an information processing program on the processor 11. The generation trigger setting unit 21 and the deletion trigger setting unit 22 realize individual management of each ledger 80 included in each node 70, instead of centralized management of multiple nodes 70. Details of the generation trigger setting unit 21 and the deletion trigger setting unit 22 will be described below with reference to Figs. 1 to 6.

[0023] [Details of the generation trigger setting section] The generation trigger setting unit 21 continuously executes the ledger generation process (see FIG. 3). In the ledger generation process, the generation trigger setting unit 21 sets a generation trigger for the ledger 80 for each node 70 included in the ledger network 60 (see FIG. 3, S11). The generation trigger may be a trigger for generating the ledger 80 for an existing node 70, or may be a trigger for newly generating a node 70 that includes the ledger 80. The system administrator sets the generation trigger for all nodes 70. On the other hand, the node operator is not given the authority to set a generation trigger. The generation trigger setting unit 21 sets a generation trigger for all nodes 70 based on a trigger setting request obtained from the administrator terminal. The set generation trigger is stored in the memory unit 13 of the ledger management device 100.

[0024] The specific contents of the generation trigger set in each node 70 are determined by the system administrator. The generation trigger setting unit 21 sets time conditions related to time, capacity conditions related to data volume, status conditions related to changes in the state of the ledger 80, etc. as activation conditions in the generation trigger. The generation trigger setting unit 21 may set activation of a deletion trigger, which will be described later, as an activation condition for the generation trigger. The generation trigger setting unit 21 may set multiple activation conditions in the generation trigger. Multiple activation conditions can be set as AND conditions or OR conditions. In addition, activation conditions once set may be changed as appropriate.

[0025] The time condition is, for example, a new year, a new fiscal year, etc. According to such a time condition, a ledger 80 for each calendar year or fiscal year is generated in each node 70 (see CY and FY in FIG. 4). In addition, when the ledger network 60 is used to store information related to a product, the time of updating the model year of the product is set as the time condition (see MY in FIG. 4). Also, one ledger 80 may be set in association with a contract unit. In this case, the time of conclusion or renewal of the contract is set as the time condition (see the bottom of FIG. 4). Furthermore, the start of a year in which a specific event is held (e.g., an Olympic year, etc.) may be set as the time condition.

[0026] Capacity conditions include when the number of blocks in the ledger 80 exceeds a certain number, or when the data size of the ledger 80 exceeds a certain amount. Status conditions include when a new ledger network 60 is created, when another ledger 80 is deleted, when another ledger 80 is generated, etc. More specifically, the deletion of an old ledger 80 can be set as a status condition. Also, in a form in which a main ledger and a sub-ledger are provided, the generation of a main ledger can be set as a status condition for the sub-ledger.

[0027] After setting the generation trigger, the generation trigger setting unit 21 continues a trigger waiting state in which it waits for the activation conditions set in the generation trigger to be satisfied. The generation trigger setting unit 21 activates the generation trigger based on the satisfaction of preset activation conditions such as time conditions, capacity conditions, and status conditions (see FIG. 3, S12). When multiple activation conditions are set, the generation trigger setting unit 21 refers to preset AND conditions or OR conditions, and activates the generation trigger when the minimum required activation conditions are satisfied. Based on the activation of the generation trigger, the generation trigger setting unit 21 generates a new ledger 80 in the node 70 to be generated (see FIG. 3, S13).

[0028] As an example, a ledger generation process will be described for a ledger network 60 (see FIG. 2) in which companies A, B, and C participate as node operators. This ledger network 60 includes at least a company A node 70a linked to company A, a company B node 70b linked to company B, and a company C node 70c linked to company C.

[0029] The generation trigger setting unit 21 sets a generation trigger whose activation condition is a change in the calendar year, according to the decision of the system administrator. The generation trigger setting unit 21 activates the generation trigger at the timing of the change in the calendar year, and generates a new ledger 80 in each node 70. For example, when the calendar year switches from 2021 to 2022, the generation trigger setting unit 21 generates a new ledger 80 in each of the company A node 70a, the company B node 70b, and the company C node 70c.

[0030] The generation trigger is set in common for all nodes 70. However, a certain node 70 may not have a ledger 80 for a certain channel 90. For example, in channel 90b in 2023, company B node 70b does not have a ledger 80 and is not participating in channel 90b (see FIG. 2).

[0031] Each ledger 80 generated in the nodes 70a to 70c forms one blockchain channel 90 that shares the data to be stored. The channel 90 may be a private channel accessible only to the system administrator and the node operator, or a public channel open to anyone other than the system administrator and the node operator. Ledgers 80 generated in 2022 belong to the 2022 channel 90a. Furthermore, ledgers 80 generated in 2023 belong to the 2023 channel 90b. As described above, when a ledger 80 is generated in each node 70 using a time condition, a channel 90 is formed for each calendar year.

[0032] In another example, the nodes 70a to 70c of each company are divided by calendar year. The generation trigger setting unit 21 also generates a node 70 including the ledger 80 at the timing of generating the ledger 80 for each calendar year based on the generation trigger. Specifically, the generation trigger setting unit 21 generates the company A node 70a for 2022, the company B node 70b for 2022, and the company C node 70c for 2022 by the activation of the generation trigger, and starts the operation of the ledger 80 for 2022 by each node 70a to 70c. Furthermore, for 2023, the generation trigger setting unit 21 generates the nodes 70a to 70c of each company that are different from those for 2022 by the activation of the generation trigger, in a state including the ledger 80 for 2023. As a result, a company A node 70a for 2023, a company B node 70b for 2023, and a company C node 70c for 2023 will be established, and operation of each of the ledgers 80 for 2023 will begin.

[0033] As yet another example, the generation trigger setting unit 21 sets a generation trigger whose activation condition is that the number of blocks in the latest ledger 80 set in each node 70 exceeds a certain number (e.g., 10,000). When the number of blocks in the latest ledger 80 in one node 70 exceeds a certain number, the generation trigger setting unit 21 activates the generation trigger and generates a new ledger 80 in this node 70.

[0034] The generation trigger setting unit 21 generates a new ledger 80 by manual operation of the system administrator, separately from the activation of the generation trigger as described above. The administrator terminal is provided with an operation (hereinafter, generation instruction operation) for selecting a node 70 to be generated and instructing the selected node 70 to generate a new ledger 80. When the system administrator or an operator belonging to the system administrator inputs a generation instruction operation to the administrator terminal, a generation request for the ledger 80 is sent from the administrator terminal to the generation trigger setting unit 21. The generation trigger setting unit 21 acquires the generation request by the system administrator from the administrator terminal. Based on the generation request, the generation trigger setting unit 21 generates a new ledger 80 for at least one node 70 specified in the generation request, without depending on the activation of the generation trigger.

[0035] [Details of the deletion trigger setting section] The deletion trigger setting unit 22 continuously executes the ledger deletion process (see FIG. 6). In the ledger deletion process, the deletion trigger setting unit 22 sets a deletion trigger for each ledger 80 provided for each node 70 (see FIG. 6, S31). The system administrator has the authority to set a deletion trigger for each ledger 80 linked to multiple (all) nodes 70. A node operator has the authority to set a deletion trigger only for ledgers 80 related to the node operator, in other words, only for ledgers 80 linked to the node operator. One node operator cannot set a deletion trigger for ledgers 80 of nodes 70 linked to another node operator.

[0036] The deletion trigger setting unit 22 sets a deletion trigger for the ledger 80 specified in the trigger setting request based on a trigger setting request obtained from an administrator terminal. The deletion trigger setting unit 22 sets a deletion trigger for the ledger 80 of the node 70 linked to the user terminal that issued the request based on a trigger setting request obtained from a user terminal. The set deletion trigger is stored in the memory unit 13 of the ledger management device 100.

[0037] The specific contents of the deletion trigger set in each ledger 80 are determined by a system administrator or a node operator who owns each ledger 80. The deletion trigger setting unit 22 sets, as the deletion trigger, a time condition related to time (see FIG. 4), a capacity condition related to the amount of data, a status condition related to a change in the state of the ledger 80, and the like as activation conditions, similar to the generation trigger set by the generation trigger setting unit 21. The deletion trigger setting unit 22 can set, in the deletion trigger, a plurality of activation conditions as AND conditions or OR conditions. The deletion trigger setting unit 22 can set, in the deletion trigger, time conditions, capacity conditions, and status conditions that are substantially the same as the generation conditions set in the generation trigger. The deletion trigger setting unit 22 can appropriately change the activation conditions once set until the deletion trigger is activated, in other words, until the ledger 80 to be deleted is deleted.

[0038] The time condition is when a certain period of time has passed since the creation date and time of the ledger 80, the last update date and time, and the last reference date and time. The capacity condition is similar to the creation condition, such as when the number of blocks in the ledger 80 exceeds a certain number, or when the data size of the ledger 80 exceeds a certain amount. The status condition is similar to the creation condition, such as when a new ledger network 60 is created, when another ledger 80 is deleted, when another ledger 80 is created, etc.

[0039] The deletion trigger setting unit 22 initially sets the deletion trigger of each ledger 80 to the deletion trigger activation condition (hereinafter, common activation condition) determined by the system administrator. As an example, the system administrator sets the common activation condition to be a predetermined period of time has passed since creation. In addition, the system administrator sets an allowable change range for the common activation condition. The allowable change range is the range within which changes to the common activation condition are permitted. For example, the system administrator restricts (prohibits) changes that shorten the time condition set as the common activation condition, while permitting changes that lengthen the time condition.

[0040] The deletion trigger setting unit 22 changes the common operating condition that is initially set in the deletion trigger to an individual operating condition determined by the node operator of each node 70. When the individual operating condition fits within the change tolerance range, the deletion trigger setting unit 22 changes it from the common operating condition to the individual operating condition. On the other hand, when the individual operating condition falls outside the change tolerance range, the deletion trigger setting unit 22 cancels the change from the common operating condition to the individual operating condition.

[0041] After setting the deletion trigger, the deletion trigger setting unit 22 continues a trigger waiting state in which it waits for the activation condition set in the deletion trigger to be satisfied. The deletion trigger setting unit 22 activates the deletion trigger based on the satisfaction of preset activation conditions such as time conditions, capacity conditions, and status conditions (see S32 in FIG. 6). When multiple activation conditions are set, the deletion trigger setting unit 22 refers to preset AND conditions or OR conditions and activates the deletion trigger based on the satisfaction of the minimum required activation conditions.

[0042] The deletion trigger setting unit 22 deletes the ledger 80 to be deleted that corresponds to the deletion trigger based on the activation of the deletion trigger (see S33 in FIG. 6). When deleting the ledger 80, the deletion trigger setting unit 22 may execute a process to delete the ledger 80 itself, or may execute an initialization process to delete only the data recorded in the ledger 80 while leaving the framework of the ledger 80 intact, and return it to its initial state.

[0043] As an example, a ledger deletion process in a ledger network 60 (see FIG. 5) in which companies A, B, and C participate as node operators will be described. The deletion trigger setting unit 22, in accordance with the decision of the system administrator, initially sets, as a common operating condition, the deletion trigger of the ledger 80 of each node 70a to 70c, that a predetermined period of time, for example, 10 years, has passed since the creation date and time. In addition, the deletion trigger setting unit 22 sets a period of time of at least a predetermined period (10 years or more) as the allowable change range.

[0044] The deletion trigger setting unit 22 changes the deletion trigger activation condition from the common activation condition to the individual activation condition, in accordance with the decision of each node operator, provided that the change does not deviate from the allowable change range. This makes it possible to extend the specified period until the deletion trigger is activated. Specifically, the ledger 80 of company A node 70a maintains the initially set common activation condition. Meanwhile, in each of the ledgers 80 of company B node 70b and company C node 70c, a time condition such as 20 years from the creation date and time or an unlimited period is newly set for the deletion trigger, in accordance with the decision of each node operator.

[0045] The deletion trigger setting unit 22 deletes the ledger 80 whose operation period determined by the system administrator has ended. The deletion trigger setting unit 22 activates the deletion trigger for the ledger 80 included in the 2022 channel 90a of the A company node 70a at the timing when the calendar year switches to 2032. On the other hand, the deletion trigger setting unit 22 suspends the activation of the deletion trigger for the ledger 80 of the B company node 70b and the ledger 80 of the C company node 70c in the 2022 channel 90a ...

[0046] As another example, the deletion trigger setting unit 22 sets a deletion trigger whose activation condition is that the number of blocks in the latest ledger 80 set in each node 70 exceeds a certain number (e.g., 10,000). When the number of blocks in the latest ledger 80 in one node 70 exceeds a certain number, the deletion trigger setting unit 22 activates the deletion trigger and generates a new ledger 80 in this node 70. In this case, the generation trigger setting unit 21 may activate a generation trigger in association with the activation of the deletion trigger.

[0047] Based on the activation of the deletion trigger, the deletion trigger setting unit 22 deletes the ledger 80 corresponding to the deletion trigger, as well as the node 70 itself that includes this ledger 80. For example, if the termination of a contract is set as the activation condition of the deletion trigger, the deletion trigger setting unit 22 activates the deletion trigger based on the termination of a contract with the node operator. In this case, the deletion trigger setting unit 22 deletes not only one or more ledgers 80 of a node 70 linked to the node operator (e.g., the Company A node 70a, see FIG. 5 ), but also the entire Company A node 70a that includes the ledger 80 from the ledger network 60.

[0048] When the activation conditions set for the multiple ledgers 80 are the same, the deletion trigger setting unit 22 activates the multiple deletion triggers and deletes the multiple ledgers 80 collectively. For example, when the deletion triggers for each ledgers 80 of the 2022 channel 90a (see FIG. 5) all remain at the common activation condition, the deletion trigger setting unit 22 deletes the entire 2022 channel 90a based on the activation of the deletion trigger. As described above, even if the deletion trigger setting unit 22 does not perform centralized management and gives the authority to select to each node operator, if the selection of each node operator is the same, it can execute a batch deletion process for the multiple ledgers 80.

[0049] The deletion trigger setting unit 22 deletes the ledger 80 by manual operation of the system administrator or node operator, separately from the operation of the deletion trigger as described above. The administrator terminal is provided with an operation (hereinafter, a deletion instruction operation) for selecting the node 70 and ledger 80 to be deleted and instructing the deletion of the ledger 80. Similarly, each user terminal is provided with a deletion instruction operation for instructing the ledger 80 to be deleted among the multiple ledgers 80 included in the own node 70. When the system administrator, the node operator, or an operator belonging to them inputs the deletion instruction operation to the administrator terminal or the user terminal, a deletion request for the ledger 80 is transmitted from each terminal to the deletion trigger setting unit 22. The deletion trigger setting unit 22 acquires the deletion request by the system administrator or the node operator from the administrator terminal or the user terminal. Based on the deletion request, the deletion trigger setting unit 22 deletes at least one ledger 80 specified in the deletion request, without depending on the operation of the deletion trigger.

[0050] (Summary of embodiments) In the embodiment described so far, instead of centralized ledger management, an individual deletion trigger is set for the ledger 80 provided for each node 70. In this way, by managing the ledger 80 individually for each node 70, it becomes possible to selectively delete the ledger 80 for each node 70 based on the activation of the deletion trigger.

[0051] More specifically, in a blockchain that is made up of many blocks strung together, if the contents of a block are changed, the consistency between the blocks before and after the block is lost. This mechanism makes it difficult to tamper with the data to be stored that is stored in the block. On the other hand, since the loss of consistency makes it difficult to delete the data to be stored that is recorded in the ledger 80, it is necessary to hold all past data to be stored. As a result, if the ledger 80 is operated for a long period of time, the storage capacity for storing the ledger 80 becomes enormous.

[0052] Therefore, a method of deleting a ledger that has been discontinued may be considered. However, as described above, it is impossible to partially delete a ledger. Furthermore, a ledger network generally has many node operators participating. Therefore, if a ledger that has been discontinued is deleted, all the data in the ledger that a particular node operator wants to keep will also be deleted.

[0053] In order to solve the above problems, in this embodiment, the ledger 80 of all the nodes 70 is not centrally managed, and each node operator can set a deletion trigger for the ledger 80 of his / her own node 70. This allows the ledger 80 to be deleted at any time. As a result, flexible management according to the needs of the node operator is realized. For example, if the ledger 80 needs to be kept for 10 years to comply with regulations, it is legally possible to delete it after 10 years. However, some node operators have a need to keep the ledger 80 for 10 years or more to refer to past data. The information processing method according to the present disclosure can appropriately meet the needs of such node operators while enabling a reduction in the storage capacity required for storing the ledger 80.

[0054] Additionally, in this embodiment, in step S31 of setting a deletion trigger, a common operating condition determined by a system administrator is initially set as the deletion trigger of each ledger 80 linked to multiple nodes 70. This allows the operating condition of the deletion trigger of each ledger 80 for nodes 70 for which the node operator has no intention of changing the deletion trigger to be unified to the common operating condition. As a result, the deletion trigger setting unit 22 can suppress variation in the operating conditions of the deletion trigger set in each ledger 80, and execute data deletion at a desired timing.

[0055] In this embodiment, in step S31 for setting the deletion trigger, the common operating condition initially set in the deletion trigger is changed to an individual operating condition corresponding to the node 70 including the ledger 80. Therefore, if the node operator intends to change the deletion trigger, the operating condition desired by the node operator is set as the operating condition. As a result, flexible deadline management for each node 70 becomes possible.

[0056] Furthermore, in this embodiment, in step S31 of setting the deletion trigger, if the individual operating conditions fall outside the change tolerance range set by the system administrator, the change from the common operating conditions to the individual operating conditions is stopped. This prevents an inappropriate deletion trigger from being set due to an erroneous decision by the node operator. For example, it is possible to prevent a storage period of less than 10 years being set even though a storage period of 10 years is stipulated by law. As a result of the above, it becomes possible to set an appropriate deletion trigger for each ledger 80 while giving each node 70 the authority to make a selection.

[0057] Additionally, in this embodiment, the node operator linked to the node 70 has the authority to set a deletion trigger only for the ledger 80 related to him / her. On the other hand, the system administrator has the authority to set a deletion trigger for each ledger 80 linked to multiple nodes 70. By setting the authorities as described above, it is possible to prevent the structure of the ledger network 60 from becoming complicated.

[0058] Furthermore, in this embodiment, in step S33 of deleting the ledger 80, in addition to the ledger 80 corresponding to the deletion trigger, the node 70 itself that includes this ledger 80 is deleted based on the activation of the deletion trigger. In this way, by deleting not only ledgers 80 that have been discontinued but also nodes 70 that are no longer needed, the storage capacity used by the ledger network 60 can be effectively reduced.

[0059] Furthermore, in this embodiment, in step S31 of setting the deletion trigger, a time condition related to time is set in the deletion trigger. Then, in step S32 of activating the deletion trigger, the deletion trigger is activated based on the establishment of the time condition. According to the above, a predetermined period for holding the ledger 80 can be selected for each node 70. In general, storage rules defined by laws and regulations are set using conditions related to time. Therefore, by setting a time condition in the deletion trigger, it is possible to easily realize the operation of the ledger 80 that complies with the storage rules defined by laws and regulations. Specifically, a specific node operator can decide to delete the ledger 80 of the first year at the timing of the 12th year. This allows selective deletion of the ledger 80 by each node 70, rather than centralized ledger management.

[0060] In addition, the deletion trigger setting unit 22 of this embodiment acquires a deletion request from a node operator or system administrator linked to the node 70 that includes the ledger 80. Then, based on the deletion request, the deletion trigger setting unit 22 deletes the ledger 80 specified in the deletion request. As described above, by providing a means for manually deleting the ledger 80 that is not dependent on the activation of a deletion trigger, more flexible operation of the ledger network 60 is realized.

[0061] Furthermore, in this embodiment, a generation trigger for the ledger 80 is set, which is determined by the system administrator. Then, based on the activation of the generation trigger, a new ledger 80 is generated for each node 70. As described above, if a ledger 80 is generated individually for each node 70, it is possible to reliably set a deletion trigger for each ledger 80 and delete each ledger 80 individually by activating the deletion trigger. In other words, it becomes possible to build a ledger network 60 that is suitable for ledger management for each node 70.

[0062] Furthermore, in this embodiment, in step S11 of setting a generation trigger, a time condition related to time is set in the generation trigger. Then, in step S12 of activating the generation trigger, the generation trigger is activated based on the establishment of the time condition. As described above, storage rules are generally set using conditions related to time. Therefore, for example, by generating a new ledger 80 for each calendar year and writing the data to be stored for that year in the ledger 80, storage of the ledger 80 in accordance with the storage rules stipulated by laws and regulations can be reliably achieved.

[0063] In addition, the generation trigger setting unit 21 of this embodiment acquires a generation request from a system administrator. Then, based on the generation request, the generation trigger setting unit 21 generates the ledger 80 specified in the generation request. As described above, by providing a means for manually generating the ledger 80 that does not depend on the activation of a generation trigger, more flexible operation of the ledger network 60 is realized.

[0064] (Other embodiments) Although one embodiment of the present disclosure has been described above, the present disclosure should not be construed as being limited to the above embodiment, and can be applied to various embodiments and combinations within the scope not departing from the gist of the present disclosure.

[0065] The ledger management device 100 of the first variant of the above embodiment shown in Fig. 7 includes a status storage unit 23 as a functional unit based on an information processing program. The status storage unit 23 stores ledger status information. The ledger status information is managed by a system administrator. The ledger status information records the state of each ledger 80 generated in the ledger network 60. As an example, the ledger status information records whether or not operation is continuing for each channel 90 as the ledger status.

[0066] In step S31 (see FIG. 6) of setting a deletion trigger, the deletion trigger setting unit 22 sets a status condition related to ledger status information as the deletion trigger. Specifically, the deletion trigger setting unit 22 sets the ledger status information becoming a status of "end of operation" as the activation condition of the deletion trigger. For example, the ledger 80 of company A node 70a (see FIG. 5) uses the above-mentioned status condition as the activation condition. On the other hand, in each of the ledgers 80 of company B node 70b and company C node 70c (see FIG. 5), other time conditions not related to ledger status information are used as the activation condition.

[0067] With the above settings, in step S32 (see FIG. 6) of activating the deletion trigger, the deletion trigger setting unit 22 establishes the status condition when the ledger status of the 2022 channel 90a becomes "end of operation". Based on the establishment of the status condition, the deletion trigger setting unit 22 activates the deletion trigger of the ledger 80 of the A company node 70a. As a result, of the multiple ledgers 80 included in the 2022 channel 90a, only the ledger 80 of the A company node 70a is selectively deleted (see FIG. 5).

[0068] As in Variation 1, by linking ledger status information to a deletion trigger, it is possible to activate the deletion triggers of many ledgers 80 collectively, and efficiently reduce the storage capacity used by the ledger network 60. Also in Variation 1, the node operator can, at his / her own discretion, separate the operation of the ledger 80 of his / her own node 70 from the ledger status information operated by the system administrator. As a result, the same effect as in the above embodiment is achieved, and selective deletion of the ledger 80 for each node 70 becomes possible.

[0069] In the second modification of the above embodiment, the function of initially setting a common operating condition in the deletion trigger is omitted. Also, in the third modification of the above embodiment, the function of setting the allowable change range is omitted. As in the second and third modifications, the process in the step of setting the deletion trigger may be modified as appropriate.

[0070] In variant 4 of the above embodiment, the authority to set deletion triggers is granted only to the node operators who own each node 70. The system administrator does not have the authority to set deletion triggers. Furthermore, in variant 5 of the above embodiment, in addition to the system administrator, a specific node operator has the authority to set generation triggers common to all nodes 70. As in variants 4 and 5 above, the authority to set deletion triggers and generation triggers may be changed as appropriate.

[0071] In the sixth modification of the above embodiment, the function of collectively deleting a plurality of ledgers 80 for each channel 90 is omitted. Also, in the seventh modification of the above embodiment, the function of collectively deleting a plurality of ledgers 80 for each node 70 is omitted. As described above, the range of the deletion targets may be changed as appropriate.

[0072] In the eighth variant of the above embodiment, the function of manually generating a new ledger 80 based on a generation request from the system administrator, regardless of the generation trigger, is omitted. Also, in the ninth variant of the above embodiment, the function of manually deleting the ledger 80 based on a deletion request from the system administrator or node operator, regardless of the deletion trigger, is omitted. As in the ninth and tenth variants above, the manual generation means and manual deletion means may be omitted as appropriate.

[0073] In the above embodiment, data to be stored can be added to the latest ledger 80 in the node 70. On the other hand, adding data to an old ledger 80 that is not the latest may be permitted or prohibited. That is, the old ledger 80 may be in a status where both addition and reference are possible, or may be in a status where only reference is possible.

[0074] The blockchain platform of the above embodiment is used, for example, for managing a supply chain. In this case, the system administrator is a finished product manufacturer that manages the supply chain, or a supervisory agency that has supervisory authority over the final products supplied by the supply chain. The node operators are the individual suppliers, transporters, and recyclers that make up the supply chain. Furthermore, the products supplied by the supply chain may be various goods, such as automobiles, batteries, semiconductors, fresh food, seafood, food, flowers, medicines, and chemicals.

[0075] The form of the ledger network 60 in the above embodiment may be modified as appropriate. For example, the ledger network 60 may be configured such that the channel 90 does not span multiple nodes 70. Furthermore, the data recorded in the ledger 80 does not need to be separated into the data body 81 and the auxiliary data 82. The auxiliary data 82 may be stored in a storage area different from the ledger 80, specifically, in an object storage provided on a cloud.

[0076] The processor of the above embodiment may be configured to include at least one arithmetic core such as a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit). The processor may further include an FPGA (Field-Programmable Gate Array), an NPU (Neural network Processing Unit), and an IP core having other dedicated functions. The processor is not limited to a chip configuration individually mounted on a printed circuit board. The processor may be implemented in an ASIC (Application Specific Integrated Circuit), an SoC (System on Chip), an FPGA, or the like.

[0077] The form of the recording medium (non-transitory tangible storage medium) employed as the storage unit in the above embodiment and storing each program may be changed as appropriate. For example, the recording medium is not limited to a configuration provided on a circuit board, and may be provided in the form of a memory card or the like, inserted into a slot, and electrically connected to a bus of a computer. Furthermore, the recording medium may be an optical disk, a hard disk drive, a solid state drive, or the like used as a source from which a program is copied or distributed to a computer.

[0078] The control unit and the method described herein may be implemented by a special-purpose computer having a processor programmed to execute one or more functions embodied in a computer program. Alternatively, the device and the method described herein may be implemented by a special-purpose hardware logic circuit. Alternatively, the device and the method described herein may be implemented by one or more special-purpose computers configured by a combination of a processor that executes a computer program and one or more hardware logic circuits. The computer program may also be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by the computer.

[0079] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple dependent claims. Some of the claims may be described in a multiple dependent form, where the subsequent claim alternatively refers to the preceding claim. Furthermore, some of the claims may be described in a multiple dependent form, where the subsequent claim alternatively refers to the preceding claim. The claims described in these multiple dependent forms define multiple technical ideas.

[0080] (Technical thought 1) An information processing method for processing information related to a plurality of nodes (70) using blockchain technology, comprising: A deletion trigger is set for a ledger (80) provided for each node and storing data to be stored that is linked to each node (S31); Activating the deletion trigger (S32); Based on the activation of the deletion trigger, the ledger corresponding to the deletion trigger is deleted (S33); The information processing method includes the steps of: (Technical thought 2) An information processing method according to technical idea 1, in which in the step of setting the deletion trigger, a common operating condition determined by a system administrator who manages the multiple nodes is initially set as the deletion trigger of each ledger linked to the multiple nodes. (Technical Thought 3) An information processing method described in Technical Idea 2, in which in the step of setting the deletion trigger, the common operating condition initially set in the deletion trigger is changed to an individual operating condition corresponding to the node that includes the ledger. (Technical Thought 4) An information processing method according to technical idea 3, in which in the step of setting the deletion trigger, if the individual operating conditions fall outside the allowable change range set by the system administrator, the change from the common operating conditions to the individual operating conditions is stopped. (Technical Thought 5) In the step of setting the deletion trigger, A node operator associated with the node has the authority to set the deletion trigger only for the ledger related to that node, An information processing method described in any one of technical ideas 1 to 4, in which a system administrator who manages multiple nodes has the authority to set the deletion trigger for each ledger linked to multiple nodes. (Technical Thought 6) An information processing method described in any one of Technical Ideas 1 to 5, in which, in the step of deleting the ledger, in addition to the ledger corresponding to the deletion trigger, the node itself containing the ledger is deleted based on the activation of the deletion trigger. (Technical Thought 7) In the step of setting the deletion trigger, a time condition related to time is set as the deletion trigger; The information processing method according to any one of Technical Ideas 1 to 6, wherein in the step of activating the deletion trigger, the deletion trigger is activated based on the establishment of the time condition. (Technical Thought 8) Obtaining a deletion request from a node operator associated with the node that includes the ledger or a system administrator that manages multiple nodes; Based on the deletion request, delete the ledger specified in the deletion request. The information processing method according to any one of Technical Ideas 1 to 7, further comprising the step of: (Technical Thought 9) Ledger status information that records the state of each ledger is managed by a system administrator that manages multiple nodes; In the step of setting the deletion trigger, a status condition related to the ledger status information is set as the deletion trigger; The information processing method according to any one of Technical Ideas 1 to 8, wherein in the step of activating the deletion trigger, the deletion trigger is activated based on establishment of the status condition. (Technical Thought 10) Setting a generation trigger for the ledger determined by a system administrator who manages the plurality of nodes (S11); Activating the generation trigger (S12); Based on the activation of the generation trigger, a new ledger is generated for each of the nodes that stores the data to be stored (S13); The information processing method according to any one of Technical Ideas 1 to 9, further comprising the step of: (Technical Thought 11) In the step of setting the generation trigger, a time condition related to time is set in the generation trigger; The information processing method according to Technical Idea 10, in which in the step of activating the generation trigger, the generation trigger is activated based on the establishment of the time condition. (Technical Thought 12) Obtaining a generation request from the system administrator; Based on the generation request, generate the ledger specified in the generation request. The information processing method according to Technical Idea 10 or 11, further comprising the step of:

[0081] (Technical Thought 1A) An information processing device that processes information related to a plurality of nodes (70) using blockchain technology, a deletion trigger setting unit (22) that sets a deletion trigger for a ledger (80) that is provided for each of the nodes and that stores data to be stored that is linked to each of the nodes; The deletion trigger setting unit is activating the deletion trigger; An information processing device that deletes the ledger corresponding to the deletion trigger based on the activation of the deletion trigger. (Technical Thought 1B) An information processing program for processing information related to a plurality of nodes (70) using blockchain technology, A deletion trigger is set for a ledger (80) provided for each node and storing data to be stored that is linked to each node (S31); Activating the deletion trigger (S32); Based on the activation of the deletion trigger, the ledger corresponding to the deletion trigger is deleted (S33); An information processing program that causes at least one processor (11) to execute a process including the steps of: (Technical Thought 1C) A storage medium that stores an information processing program for processing information related to a plurality of nodes (70) using blockchain technology and is readable by a computer (100), The information processing program includes: A deletion trigger is set for a ledger (80) provided for each node and storing data to be stored that is linked to each node (S31); Activating the deletion trigger (S32); Based on the activation of the deletion trigger, the ledger corresponding to the deletion trigger is deleted (S33); A storage medium configured to cause at least one processor (11) to perform processes including: [Explanation of symbols]

[0082] 11 processors, 70 nodes, 80 ledgers

Claims

1. An information processing method for processing information related to a plurality of nodes (70) using blockchain technology, comprising: A deletion trigger is set for a ledger (80) provided for each node and storing data to be stored that is linked to each node (S31); Activating the deletion trigger (S32); Based on the activation of the deletion trigger, the ledger corresponding to the deletion trigger is deleted (S33). The information processing method includes the steps of:

2. The information processing method according to claim 1 , wherein in the step of setting the deletion trigger, a common operating condition determined by a system administrator who manages the multiple nodes is initially set as the deletion trigger for each ledger linked to the multiple nodes.

3. 3. The information processing method according to claim 2, wherein in the step of setting the deletion trigger, the common operating condition initially set in the deletion trigger is changed to an individual operating condition corresponding to the node that includes the ledger.

4. 4. The information processing method according to claim 3, wherein in the step of setting the deletion trigger, if the individual operating condition falls outside a permissible change range set by the system administrator, the change from the common operating condition to the individual operating condition is cancelled.

5. In the step of setting the deletion trigger, A node operator associated with the node has the authority to set the deletion trigger only for the ledger related to that node, The information processing method according to claim 1 , wherein a system administrator who manages the plurality of nodes has authority to set the deletion trigger for each of the ledgers linked to the plurality of nodes.

6. 2 . The information processing method according to claim 1 , wherein in the ledger deleting step, in addition to deleting the ledger corresponding to the deletion trigger, the node itself including the ledger is deleted based on the activation of the deletion trigger.

7. In the step of setting the deletion trigger, a time condition related to time is set as the deletion trigger; The information processing method according to claim 1 , wherein in the step of activating the deletion trigger, the deletion trigger is activated based on the establishment of the time condition.

8. Obtaining a deletion request from a node operator associated with the node that includes the ledger or a system administrator that manages multiple nodes; Based on the deletion request, delete the ledger specified in the deletion request. The information processing method according to claim 1 , further comprising the step of:

9. Ledger status information that records the state of each ledger is managed by a system administrator that manages multiple nodes; In the step of setting the deletion trigger, a status condition related to the ledger status information is set as the deletion trigger; The information processing method according to claim 1 , wherein in the step of activating the deletion trigger, the deletion trigger is activated based on the establishment of the status condition.

10. A trigger for generating the ledger is set, the trigger being determined by a system administrator who manages the plurality of nodes (S11); Activating the generation trigger (S12); Based on the activation of the generation trigger, a new ledger is generated for each of the nodes that stores the data to be stored (S13). The information processing method according to claim 1 , further comprising the step of:

11. In the step of setting the generation trigger, a time condition related to time is set in the generation trigger; The information processing method according to claim 10 , wherein in the step of activating the generation trigger, the generation trigger is activated based on the establishment of the time condition.

12. Obtaining a generation request from the system administrator; Based on the generation request, generate the ledger specified in the generation request. The information processing method according to claim 10 or 11, further comprising the step of:

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