JP7677619B2 - Workflow Management System - Google Patents

Description

The present invention relates to a workflow management system.

In recent years, technologies for realizing distributed public ledgers such as blockchain have been developing rapidly. For example, Patent Literature 1 discloses a technology in which information such as orders, shipments, contract requests, changes, and approvals are reflected in a blockchain, and approvals are made on a group basis of multiple companies involved in a supply chain.

JP 2020-86478 A

The inventors of the present application have focused on the robustness of blockchain and its characteristics as a public ledger, and have come to recognize the possibility of using blockchain to manage the process from application to issuance of any certificate (such as a certificate of possession of an official qualification or a certificate of bank balance), thereby increasing the transparency of the certificate issuance process and achieving traceability, and ultimately increasing the reliability of the certificate.

The present invention was made in consideration of these points, and aims to provide technology that increases the reliability of certificates.

The first aspect of the present invention is a workflow management system. This system includes a requester terminal used by a requester who requests a worker to perform a task, a worker terminal used by a worker who performs the task, a referrer terminal used by a referrer who refers to the results of the task, a blockchain that stores the processing contents of each stage in a workflow between the requester terminal, the worker terminal, and the referrer terminal, a workflow control device that is connected to the requester terminal, the worker terminal, the referrer terminal, and the blockchain in a communicable manner via a communication network and manages the workflow by referring to the blockchain, and (1) a requester public key that is the public key of the requester. The system includes a signature management device that manages (1) signed requester information in which information including an open key and requester identification information for identifying the requester is signed with a requester private key that is a private key corresponding to the requester public key, (2) signed worker information in which information including a worker public key that is a public key of the worker and worker identification information for identifying the worker is signed with a worker private key that is a private key corresponding to the worker public key, and (3) signed referrer information in which information including a referrer public key that is a public key of the referrer and referrer identification information for identifying the referrer is signed with a referrer private key that is a private key corresponding to the referrer public key.

The system may further include an auditor terminal used by an auditor who audits the content of the work, and the blockchain may store the processing content of each stage in the workflow between the client terminal, the worker terminal, and the viewer terminal, and the workflow control device may be connected in a communicable manner to the client terminal, the worker terminal, the auditor terminal, the viewer terminal, and the blockchain via a network, and the signature management device may further manage signed auditor information in which information including an auditor public key, which is the public key of the auditor, and auditor identification information for identifying the auditor, is signed with an auditor private key, which is the private key corresponding to the auditor public key.

The client terminal may include a work request information generation unit that generates signed work request information by signing information including the content of the work, the client identification information, the worker identification information, and the viewer identification information, including the identification information of a person who is authorized to access the information, with the client private key, and a communication unit that transmits the signed work request information to the workflow control device, and the workflow control device may include a communication unit that receives the signed work request information from the client terminal, and a blockchain management unit that registers the received signed work request information in the blockchain.

The communication unit of the workflow control device may notify the worker terminal of a message indicating that the work has been requested, and the worker terminal may include a work request information acquisition unit that acquires the signed work request information from the blockchain via the workflow control device upon receiving the notification regarding the work request, and a signature verification unit that uses the client public key acquired from the signature management device to verify whether the signature on the signed work request information is a signature affixed with the client private key.

The worker terminal may further include a result information generation unit that generates signed result information by signing, with the worker private key, information indicating the results of the work included in the signed work request information, including the identification information of the person who is authorizing access to the information; an audit request information generation unit that generates signed audit request information by signing, with the worker private key, information including the worker identification information and the auditor identification information, including the identification information of the person who is authorizing access to the information; and a communication unit that transmits the signed result information and the signed audit request information to the workflow control device, and a blockchain management unit of the workflow control device may register the signed result information and the signed audit request information in the blockchain.

The communication unit of the workflow control device may notify the auditor terminal of a message indicating that a request for an audit of the results of the work has been received, and the auditor terminal may include an audit information acquisition unit that, upon receiving the notification regarding the audit request, acquires the signed result information and the signed audit request information from the blockchain via the workflow control device, and a signature verification unit that uses the worker public key acquired from the signature management device to verify whether the signatures of the signed result information and the signed audit request information are signatures affixed with the worker private key.

The auditor terminal may further include an audit information generation unit that generates signed audit information by signing, with the auditor private key, information indicating the audit results of the work included in the signed result information, the information including the identification information of the person who grants access to the information; a confirmation request information generation unit that generates signed confirmation request information by signing, with the auditor private key, information including the auditor identification information and the viewer identification information, the information including the identification information of the person who grants access to the information; and a communication unit that transmits the signed audit information and the signed confirmation request information to the workflow control device, and a blockchain management unit of the workflow control device may register the signed audit information and the signed confirmation request information in the blockchain.

The communication unit of the workflow control device may notify the viewer terminal of a message indicating that a request for confirmation of the audit results has been received, and the viewer terminal may include a confirmation information acquisition unit that acquires the signed audit information and the signed confirmation request information from the blockchain via the workflow control device upon receiving the notification regarding the confirmation request, and a signature verification unit that uses the auditor public key acquired from the signature management device to verify whether the signatures of the signed audit information and the signed confirmation request information are signatures affixed with the auditor private key.

The viewer terminal may further include a confirmed information generation unit that generates signed confirmed information by signing information indicating the audit confirmation result included in the signed audit information, the information including the identification information of the person who is authorized to access the information, with the viewer private key, and a communication unit that transmits the signed confirmed information to the workflow control device, and the blockchain management unit of the workflow control device may register the signed confirmation information in the blockchain.

The viewer terminal may further include an access right setting unit that generates signed access permission information by signing information including identification information of a person who is permitted to access each of the signed result information and the signed audit information with the viewer private key, a communication unit of the viewer terminal may transmit the signed access permission information to the workflow control device, and a blockchain management unit of the workflow control device may register the signed access permission information in the blockchain.

In addition, any combination of the above components, and any conversion of the present invention into a method, device, system, computer program, data structure, recording medium, etc., are also valid aspects of the present invention.

The present invention provides technology that increases the reliability of certificates.

FIG. 1 is a diagram for explaining an overview of a workflow management system according to an embodiment. 2 is a diagram illustrating a schematic functional configuration of a client terminal, an operator terminal, a reference terminal, and an inspector terminal according to an embodiment; FIG. 2 is a diagram illustrating a data structure of a signature database managed by a signature management device according to an embodiment. FIG. 11 is a sequence diagram illustrating the flow of a task request process and a signature verification process executed in the workflow management system according to the embodiment. FIG. 11 is a sequence diagram illustrating a flow of a registration process of a work result and an audit request executed in the workflow management system according to the embodiment. FIG. 11 is a sequence diagram illustrating a flow of processing for executing an audit and requesting confirmation of the audit result, which is executed in the workflow management system according to the embodiment. FIG. A sequence diagram for explaining the flow of a notification process for a request to confirm supervision results and audit results, which is executed in a workflow management system according to an embodiment. 11 is a sequence diagram for explaining the flow of a result confirmation process and an access right setting process executed in the workflow management system according to the embodiment. FIG. FIG. 2 is a diagram illustrating an example of a data structure of a blockchain according to an embodiment.

<Overview of the embodiment>
1 is a diagram for explaining an overview of a workflow management system S according to an embodiment of the present invention. The overview of the workflow management system S according to the embodiment of the present invention will be described below with reference to FIG.

The workflow management system S according to an embodiment of the present invention is a system for managing and visualizing the flow of certificate issuance requests, issuance work, and sending of the certificate to those who refer to the certificate using a blockchain B. The workflow management system S according to an embodiment also manages audit work by third parties on issued certificates as necessary. For this reason, as shown in FIG. 1, the workflow management system S has a requester terminal 1, a worker terminal 2, a referrer terminal 3, an auditor terminal 4, a workflow control device 5, a signature management device 6, and a blockchain B connected in a manner that allows communication via a communication network N.

The requester terminal 1 is a terminal used by a requester who requests the issuance of a certificate. The worker terminal 2 is a terminal used by a worker who carries out the issuance work of the certificate requested by the requester. The referrer terminal 3 is a terminal used by a referrer who refers to the certificate issued as a result of the issuance work by the worker. The auditor terminal 4 is a terminal used by an auditor who audits the content of the issuance work by the worker. The blockchain B functions as a public ledger that stores the processing content of each stage in the workflow between the requester terminal, the worker terminal, and the referrer terminal. Note that if the requester of the issuance of the certificate and the referrer who uses the certificate are the same person, the requester terminal 1 and the referrer terminal 3 are the same terminal.

The workflow control device 5 is a terminal used by an administrator of the workflow management service provided by the workflow management system S according to the embodiment. The workflow control device 5 is connected in a communicable manner to the client terminal 1, the worker terminal 2, the referrer terminal 3, the auditor terminal 4, and the blockchain B via the communication network N, and manages the workflow by referring to the blockchain B.

In the workflow management system S according to the embodiment, the above-mentioned requesters, workers, viewers, and auditors are so-called members of the workflow management service provided by the workflow management system S, and the requesters, workers, viewers, and auditors are each registered as members of the workflow management service in advance. As will be described in detail later, the signature management device 6 registers and manages information on the requesters, workers, viewers, and auditors. In the sense that the signature management device 6 manages information on the requesters, workers, viewers, and auditors, the requesters, workers, viewers, and auditors are known to the administrator of the workflow management service (Know Your Customer; KYC).

In this way, in the workflow management system S according to the embodiment, the workflow control device 5 manages the certificate issuance process using the blockchain B. The blockchain B functions as a public ledger, and can be referenced by any member of the workflow management service provided by the workflow management system S who is permitted to access it. Therefore, the workflow management system S according to the embodiment can increase the transparency of the certificate issuance process and achieve traceability, thereby increasing the reliability of the certificate.

<Functional configuration of client terminal 1 according to the embodiment>
2 is a diagram illustrating a schematic functional configuration of each of a client terminal 1, a worker terminal 2, a referrer terminal 3, an auditor terminal 4, and a workflow control device 5 according to an embodiment. The client terminal 1 includes a memory unit 10, a communication unit 11, and a control unit 12. The worker terminal 2 includes a memory unit 20, a communication unit 21, and a control unit 22. The referrer terminal 3 includes a memory unit 30, a communication unit 31, and a control unit 32. The auditor terminal 4 includes a memory unit 40, a communication unit 41, and a control unit 42. The workflow control device 5 includes a memory unit 50, a communication unit 51, and a control unit 52.

In FIG. 2, the arrows indicate the main data flows, and there may be data flows not shown in FIG. 2. In FIG. 2, each functional block indicates a functional configuration, not a hardware (device) configuration. Therefore, each functional block of the requester terminal 1, worker terminal 2, referrer terminal 3, and auditor terminal 4 shown in FIG. 2 may be implemented in a single device, or may be implemented separately in multiple devices. Data may be exchanged between functional blocks via any means, such as a data bus, a network, or a portable storage medium.

The storage unit 10 is a large-capacity storage device such as a ROM (Read Only Memory) that stores the BIOS (Basic Input Output System) of the computer that realizes the requester terminal 1, a RAM (Random Access Memory) that serves as the working area of the requester terminal 1, an HDD (Hard Disk Drive) or an SSD (Solid State Drive) that stores the OS (Operating System), application programs, and various information referenced when the application programs are executed.

The communication unit 11 is a communication interface that enables the client terminal 1 to exchange information with external devices, and is realized, for example, by a known Wi-Fi (registered trademark) module, a mobile communication module, a LAN (Local Area Network) module, etc.

The control unit 12 is a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit) of the client terminal 1, and functions as a work request information generation unit 120 by executing a program stored in the memory unit 10.

The storage unit 20 is a large-capacity storage device such as a ROM that stores the BIOS of the computer that realizes the worker terminal 2, a RAM that serves as the working area of the worker terminal 2, an OS, application programs, and a variety of information referenced when the application programs are executed, such as an HDD or SSD.

The communication unit 21 is a communication interface that enables the worker terminal 2 to exchange information with external devices, and is realized, for example, by a known Wi-Fi module, mobile communication module, LAN module, etc. The control unit 22 is a processor such as a CPU or GPU of the worker terminal 2, and functions as a work request information acquisition unit 220, a signature verification unit 221, a result information generation unit 222, and an audit request information generation unit 223 by executing programs stored in the storage unit 20.

The storage unit 30 is a large-capacity storage device such as a ROM that stores the BIOS of the computer that realizes the user terminal 3, a RAM that serves as the working area of the user terminal 3, an OS, application programs, and a HDD or SSD that stores various information referenced when the application programs are executed.

The communication unit 31 is a communication interface that enables the referrer terminal 3 to exchange information with external devices, and is realized, for example, by a known Wi-Fi module, mobile communication module, LAN module, etc. The control unit 32 is a processor such as a CPU or GPU of the referrer terminal 3, and functions as a confirmation information acquisition unit 320, a signature confirmation unit 321, a confirmed information generation unit 322, and an access right setting unit 323 by executing a program stored in the storage unit 30.

The storage unit 40 is a large-capacity storage device such as a ROM that stores the BIOS of the computer that realizes the auditor terminal 4, a RAM that serves as the working area of the auditor terminal 4, an HDD or SSD that stores the OS, application programs, and various information referenced when the application programs are executed.

The communication unit 41 is a communication interface that enables the auditor terminal 4 to exchange information with external devices, and is realized, for example, by a known Wi-Fi module, mobile communication module, LAN module, etc. The control unit 42 is a processor such as a CPU or GPU of the auditor terminal 4, and functions as an audit information acquisition unit 420, a signature verification unit 421, an audit information generation unit 422, and a confirmation request information generation unit 423 by executing programs stored in the storage unit 40.

The storage unit 50 is a large-capacity storage device such as a ROM that stores the BIOS of the computer that realizes the workflow control device 5, a RAM that serves as the working area of the workflow control device 5, an OS, application programs, and a variety of information referenced when the application programs are executed, such as an HDD or SSD.

The communication unit 51 is a communication interface that enables the workflow control device 5 to exchange information with external devices, and is realized, for example, by a known Wi-Fi module, mobile communication module, LAN module, etc. The control unit 52 is a processor such as a CPU or GPU of the workflow control device 5, and functions as the blockchain management unit 520 by executing programs stored in the memory unit 50.

Figure 3 is a diagram showing a schematic data structure of a signature database managed by a signature management device 6 according to an embodiment. The signature management device 6 is a device that manages users who are members of the workflow management service provided by the workflow management system S, independent of the workflow control device 5. As shown in Figure 3, the signature management device 6 assigns unique identification information to each user, and registers and manages information about each user in the signature database.

Specifically, in the example of the signature database shown in FIG. 3, the requester identification information for identifying the requester is ID000001, and the worker identification information for identifying the worker is ID000002. Similarly, the auditor identification information for identifying the auditor is ID000003, and the viewer identification information for identifying the viewer is ID000004.

In the example shown in FIG. 3, the signature management device 6 associates the client identification information with a client public key, which is the public key of the client, and stores them in the signature database. Here, the client public key is a public key of a known public key cryptography system, and is generated by the client terminal 1 together with a client private key, which is a private key corresponding to the client public key. The signature management device 6 stores information including the client public key and the client identification information in the signature database as signed client information signed with the client private key. Although not shown in FIG. 3, the signature management device 6 may also store the client's name, address, etc., in addition to the client public key and client identification information, as signed request information in the signature database.

Similarly, the signature management device 6 stores in the signature database signed worker information, which is information including the worker public key, which is the public key of the worker, and worker identification information, signed with the worker private key, which is the private key corresponding to the worker public key. The signature management device 6 also stores in the signature database signed referrer information, which is information including the referrer public key, which is the public key of the referrer, and referrer identification information, signed with the referrer private key, which is the private key corresponding to the referrer public key. Furthermore, the signature management device 6 further stores and manages in the signature database signed auditor information, which is information including the auditor public key, which is the public key of the auditor, and auditor identification information, signed with the auditor private key, which is the private key corresponding to the auditor public key.

In this way, in the workflow management system S according to the embodiment, by having the signature management device 6 manage information including the public keys of the requester, worker, auditor, and viewer in advance, it is possible to guarantee the KYC of the workflow management service provided by the workflow management system S.

<Process flow of workflow management executed in the workflow management system S>
Next, a process flow of workflow management executed in the workflow management system S according to the embodiment will be described with reference to FIG. 2 and FIG. 4 to FIG.

(Work request and signature confirmation)
FIG. 4 is a sequence diagram for explaining the flow of a work request process and a signature verification process executed in the workflow management system S according to the embodiment.

The work request information generating unit 120 of the client terminal 1 generates signed work request information signed with the client's private key, which information includes the work content, client identification information, worker identification information, and referrer identification information (S2). Here, the "work" refers to the content that the client requests a different worker to carry out, and one example is the creation of a certificate of the deposit balance. In this case, the client designates the financial institution that manages the client's account as the worker, and includes worker identification information that identifies the financial institution in the work request information.

The content of the work that the client terminal 1 requests of the worker may be highly confidential, and in such cases it is desirable to place restrictions on access to the work request information, such as reading and writing. For this reason, the work request information generation unit 120 of the client terminal 1 generates work request information by including identification information of the person who is authorized to access the work request information. Optionally, the client terminal 1 may link identification information of persons other than the financial institution with access rights and include them in the work request information. This allows the client to set the persons who are authorized to access the work request information and the scope of access (read only, writing also permitted, etc.).

The communication unit 11 of the client terminal 1 transmits the signed work request information generated by the work request information generation unit 120 to the workflow control device 5 (S4). The communication unit 51 of the workflow control device 5 receives the signed work request information from the client terminal 1 (S6). The blockchain management unit 520 of the workflow control device 5 registers the signed work request information received by the communication unit 51 in the blockchain B (S8).

The communication unit 51 of the workflow control device 5 notifies the worker terminal 2 of a message indicating that a work request has been received from the client terminal 1 (S10). The communication unit 21 of the worker terminal 2 receives the notification regarding the work request from the workflow control device 5 (S12). When the communication unit 21 receives the notification regarding the work request, the work request information acquisition unit 220 of the worker terminal 2 acquires signed work request information from the blockchain B via the workflow control device 5 (S14).

The signature verification unit 221 of the worker terminal 2 references the client identification information included in the signed work request information and obtains the client public key from the signature management device 6 (S16). In this case, the signed work request information contains the worker identification information as identification information of the person permitted to access the information. The signature verification unit 221 of the worker terminal 2 uses the client public key obtained from the signature management device 6 to verify whether the signature on the signed work request information is a signature affixed with the client's private key (S18). By verifying that the client's signature is affixed to the signed work request information, the worker terminal 2 can verify that the work request is a legitimate work request from the client.

(Registration of work results and audit requests)
FIG. 5 is a sequence diagram illustrating the flow of a process for registering work results and an audit request executed in the workflow management system S according to the embodiment.

The result information generating unit 222 of the worker terminal 2 acquires from the worker the results of the work performed by the worker that is included in the signed work request information (S20). The result information generating unit 222 of the worker terminal 2 signs the result information indicating the results of the work that is included in the signed work request information with the worker's private key to generate signed result information (S22). Note that, similar to the work request information described above, the result information generating unit 222 generates signed result information that includes identification information of the person who is authorized to access the result information.

The audit request information generating unit 223 of the worker terminal 2 generates signed audit request information by signing information including the worker identification information and the auditor identification information with the worker private key (S24). The audit request information generating unit 223 generates signed audit request information by including identification information of the person who is authorized to access the audit request information.

The communication unit 21 of the worker terminal 2 transmits the signed result information and the signed audit request information to the workflow control device 5 (S26). The communication unit 51 of the workflow control device 5 receives the signed result information and the signed audit request information from the worker terminal 2 (S28).

The blockchain management unit 520 of the workflow control device 5 registers the signed result information and the signed audit request information in the blockchain B (S30). This allows a person who is permitted to access the signed result information to refer to the result information via the workflow control device 5.

(Performing an audit and requesting confirmation of the audit results)
FIG. 6 is a sequence diagram for explaining the flow of processing for executing an audit and requesting confirmation of the audit result, which is executed in the workflow management system S according to the embodiment.

The communication unit 51 of the workflow control device 5 notifies the auditor terminal 4 of a message indicating that a request for an audit of the work results has been made (S32). The communication unit 41 of the auditor terminal 4 receives a message indicating that a request for an audit of the work results has been made from the workflow control device 5 (S34).

When the communication unit 41 receives a notification regarding an audit request from the workflow control device 5, the audit information acquisition unit 420 of the auditor terminal 4 acquires signed result information from the blockchain B via the workflow control device 5 (S36), and also acquires signed audit request information (S38).

The signature verification unit 421 of the auditor terminal 4 references the worker identification information included in the signed audit request information and obtains the worker public key from the signature management device 6 (S40). In this case, the signed audit request information contains the auditor identification information as the identification information of the person who is permitted to access the information.

The signature verification unit 421 of the auditor terminal 4 uses the worker public key obtained from the signature management device 6 to verify whether the signatures on the signed result information and the signed audit request information are both signed with the worker's private key (S42). By verifying that the signed result information and the signed audit request information are both signed with the worker's signature, the auditor terminal 4 can verify that the work was performed by the worker and that the audit request is a legitimate request from the worker himself/herself.

The audit information generating unit 422 of the auditor terminal 4 obtains from the auditor the results of the audit performed by the auditor that is included in the signed audit request information (S44). The audit information generating unit 422 of the auditor terminal 4 signs the audit information indicating the results of the audit that is included in the signed audit request information with the auditor's private key to generate signed audit information (S46). The audit information generating unit 422 generates the signed audit information by including identification information of the person who is authorized to access the audit information.

The confirmation request information generation unit 423 of the auditor terminal 4 signs the information, including the auditor identification information and the viewer identification information, including the identification information of the person who is authorized to access the information, with the auditor private key to generate signed confirmation request information (S48).

(Notification of request for confirmation of work results and audit results)
FIG. 7 is a sequence diagram for explaining the flow of a process for notifying a request for confirmation of supervision results and audit results, which is executed in the workflow management system S according to the embodiment.

The communication unit 41 of the auditor terminal 4 transmits the signed audit information and the signed confirmation request information to the workflow control device 5 (S50). The communication unit 51 of the workflow control device 5 receives the signed audit information and the signed confirmation request information from the workflow control device 5 (S52). The blockchain management unit 520 of the workflow control device 5 registers the signed audit information and the signed confirmation request information in the blockchain B (S54). This allows a person who is permitted to access the signed audit information to refer to the result information via the workflow control device 5. Similarly, a person who is permitted to access the signed confirmation request information can refer to the result information via the workflow control device 5.

The communication unit 51 of the workflow control device 5 notifies the referrer terminal 3 of a message indicating that a request for confirmation of the audit results has been made (S56). The communication unit 31 of the referrer terminal 3 receives a message indicating that a request for confirmation of the audit results has been made from the workflow control device 5 (S58).

When the communication unit 31 receives a notification regarding a confirmation request, the confirmation information acquisition unit 320 of the viewer terminal 3 acquires the signed audit information and the signed confirmation request information from the blockchain B via the workflow control device 5 (S60).

(Processing for confirming work results and setting access rights)
FIG. 8 is a sequence diagram for explaining the flow of the result confirmation process and the access right setting process executed in the workflow management system S according to the embodiment.

The signature verification unit 321 of the access terminal 3 references the auditor identification information obtained from either the signed audit information or the signed verification request information, and obtains the auditor public key from the signature management device 6 (S62). In this case, the signed audit information and the signed verification request information contain accessor identification information as identification information of the person who is permitted to access those pieces of information.

The confirmed information generating unit 322 of the referrer terminal 3 uses the auditor public key obtained from the signature management device 6 to confirm whether the signatures of the signed audit information and the signed confirmation request information are signed with the auditor private key (S64). By confirming that the auditor's signature is attached to each of the signed audit information and the signed confirmation request information, the referrer terminal 3 can confirm that the audit was performed by the auditor and that the confirmation request is a request from the auditor himself.

The confirmed information generation unit 322 of the referrer terminal 3 generates signed confirmed information by signing, with the referrer private key, information indicating the audit confirmation results included in the signed audit information, including the identification information of the person who is authorized to access the information (S66). The communication unit 31 of the referrer terminal 3 transmits the signed confirmed information to the workflow control device 5 (S68).

The communication unit 51 of the workflow control device 5 receives the signed confirmation information from the workflow control device 5 (S70). The blockchain management unit 520 of the workflow control device 5 registers the signed confirmation information in the blockchain B (S72). This allows a person who is permitted to access the signed confirmation information to refer to the result information via the workflow control device 5.

As mentioned above, an example of a task that a client may request a worker to prepare is a certificate of the bank balance at which the client has an account. In addition to the client himself, other people who may view such a balance certificate may include, for example, an heir. For this reason, the viewer may wish to disclose the results of the work or the audit to third parties other than the client or the viewer.

The access permission setting unit 323 of the referrer terminal 3 then generates signed access permission information by signing information including the identification information of the person who is permitted to access each of the signed result information and the signed audit information with the referrer's private key (S74). The communication unit 31 of the referrer terminal 3 transmits the signed access permission information to the workflow control device 5 (S76).

The communication unit 51 of the workflow control device 5 receives the signed access permission information from the referrer terminal 3 (S78). The blockchain management unit 520 of the workflow control device 5 registers the signed access permission information in the blockchain B (S80). This allows the referrer terminal 3 to disclose the results of work and audits to third parties.

Figure 9 is a diagram showing a schematic example of a data structure of a blockchain B according to an embodiment. As shown in Figure 9, the blockchain B stores a number of data blocks D called blocks in a linked manner. In Figure 7, a first block D1 and a second block D2 are shown. Each data block D stores the hash value of the previous data block D and one or more pieces of flow information.

Each flow information stores a series of information from the request to the granting of access rights. Specifically, each flow information stores signed work request information, signed result information, signed audit request information, signed audit information, signed confirmation request information, signed confirmation information, and signed access permission information. The blockchain management unit 520 of the workflow control device 5 collects a predetermined number of flow information into one data block D and attaches it to the end of the blockchain B. Because the blockchain is highly resistant to tampering, the blockchain B functions as a public ledger in which the history of past flows is accurately recorded.

<Scenes in which the workflow management system S according to the embodiment is used>
The workflow management service provided by the workflow management system S according to the embodiment is used to visualize the process from application to issuance of some kind of certificate, such as a certificate of possession of an official qualification or a certificate of bank balance, thereby increasing the reliability of the certificate.

As an example, we will explain the case where a requester wishes to issue a balance certificate for his or her own account. In this case, the requester specifies the identification information of the bank that will issue the balance certificate as the worker identification information, and the identification information of the person to whom the balance certificate will be given as the referrer identification information, and sets access rights for them.

The worker who issued the balance certificate sets the access rights by specifying the identification information of the auditor who will audit the balance certificate as the auditor identification information. The auditor audits the contents of the balance certificate created by the worker as a third party. The workflow control device 5 registers these work details and access rights together with the registration date and time in the blockchain B. In this way, the seal management system S of the embodiment can achieve transparency and traceability of the workflow and improve the reliability of the certificate.

<Effects of the client terminal 1 according to the embodiment>
As described above, the client terminal 1 according to the embodiment can provide a technique for improving the reliability of a certificate.

Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the invention. For example, all or part of the device can be configured by distributing or integrating functionally or physically in any unit. In addition, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the present embodiments.

<First Modification>
In the above, a case has been described where the workflow of the workflow management service provided by the workflow management system S is processed in the order of requesting certificate issuance, issuing the certificate, auditing the issued certificate, and referencing the certificate. However, the workflow of the workflow management service provided by the workflow management system S is not necessarily processed in the above order, and for example, there may be no audit flow. In this case, after the blockchain management unit 520 of the workflow control device 5 registers the signed result information received from the worker terminal 2 in the blockchain B, the communication unit 51 of the workflow control device 5 notifies the referrer terminal 3 of a message indicating that a request for confirmation of the work result has been made.

<Second Modification>
In the above, the client terminal 1, the worker terminal 2, the referrer terminal 3, and the auditor terminal 4 have been mainly described on the assumption that they are operated by a client, a worker, a referrer, and an auditor, respectively. However, at least one operation of at least one of these terminals may be automatically operated by the system without human intervention. For example, in the case of a simple task such as the worker terminal 2 acquiring the contents of a work request from the blockchain B, the worker terminal 2 may be automated by executing an acquisition program. This can reduce the operator's operations.

<Third Modification>
In the above, a case has been described in which a requester requests a task to one requestee (for example, a bank where the requester has an account). However, a worker may request tasks to multiple requestees. For example, a worker may specify a group consisting of multiple workers and request tasks from each member of the group. In this case, the task requested by the requester may be carried out by any one of the members of the group.

As another example, consider the case where the workflow management service provided by the workflow management system according to the embodiment is a grade management service that manages the grades of students at a cram school or school. In this case, the client is the student at the cram school or school, and the workers are teachers in charge of each subject, such as Japanese, mathematics, and English. The students request each teacher to grade the tests they take at home and record the grades according to the subject of the test. In such a case, the student who requests the work will request multiple workers who are teachers for each subject.

1...Client terminal 10...Memory unit 11...Communication unit 12...Control unit 120...Work request information generation unit 2...Worker terminal 20...Memory unit 21...Communication unit 22...Control unit 220...Work request information acquisition unit 221...Signature confirmation unit 222...Result information generation unit 223...Audit request information generation unit 3...Reference terminal 30...Memory unit 31...Communication unit 32...Control unit 320...Confirmation information acquisition unit 321...Signature confirmation unit 322...Confirmed information generation unit 323...Access right setting unit 4...Auditor terminal 40...Memory unit 41...Communication unit 42...Control unit 420...Audit information acquisition unit 421...Signature confirmation unit 422...Audit information generation unit 423...Confirmation request information generation unit 5...Workflow control device 50...Memory unit 51...Communication unit 52...Control unit 520...Blockchain management unit 6...Signature management device B...Blockchain N...Communication network S...Workflow management system

Claims (8)

A requester terminal used by a requester who requests a task to a worker;
A worker terminal used by a worker who performs the work; and
A referrer terminal used by a referrer who refers to the result of the work;
A blockchain that stores processing details of each stage in a workflow between the client terminal, the worker terminal, and the reference terminal;
A workflow control device that is connected to the client terminal, the worker terminal, the reference terminal, and the blockchain in a communicable manner via a communication network and manages the workflow by referring to the blockchain;
(1) signed requester information in which information including a requester public key, which is a public key of the requester, and requester identification information for identifying the requester is signed with a requester private key, which is a private key corresponding to the requester public key; (2) signed worker information in which information including a worker public key, which is a public key of the worker, and worker identification information for identifying the worker is signed with a worker private key, which is a private key corresponding to the worker public key; and (3) signed referrer information in which information including a referrer public key, which is a public key of the referrer, and referrer identification information for identifying the referrer is signed with a referrer private key, which is a private key corresponding to the referrer public key;
Equipped with
The requester terminal,
a work request information generating unit that generates signed work request information by signing information including the content of the work, the requester identification information, the worker identification information, and the access person identification information, the information including the identification information of a person who is authorized to access the information, with the requester private key;
a communication unit that transmits the signed work request information to the workflow control device,
The workflow control device includes:
a communication unit that receives the signed work request information from the client terminal and notifies the worker terminal of a message indicating that the work has been requested;
a blockchain management unit that registers the received signed work request information in the blockchain;
The worker terminal includes:
a work request information acquisition unit that acquires the signed work request information from the blockchain via the workflow control device upon receiving a notification regarding the work request;
a signature verification unit that uses the client public key acquired from the signature management device to verify whether or not the signature of the signed work request information is a signature affixed with the client private key;
a result information generating unit that generates signed result information by signing information indicating a result of the work included in the signed work request information, the information including identification information of a person who is authorized to access the information, with the worker private key;
a communication unit that transmits the signed result information to the workflow control device;
A block chain management unit of the workflow control device registers the signed result information in the block chain,
The reference terminal is
an access right setting unit that generates signed access permission information by signing information including identification information of a person who is permitted to access the signed result information with the access right private key;
a communication unit that transmits the signed access permission information to the workflow control device,
A blockchain management unit of the workflow control device registers the signed access permission information in the blockchain.
Workflow management system. An auditor terminal used by an auditor who audits the contents of the work is further provided,
The blockchain stores the processing contents of each stage in a workflow between the client terminal, the worker terminal, the auditor terminal, and the reference terminal,
The workflow control device is connected to the client terminal, the worker terminal, the auditor terminal, the reference terminal, and the blockchain via a network in a communicable manner,
the signature management device further manages signed auditor information, which is information including an auditor public key that is a public key of the auditor and auditor identification information for identifying the auditor, signed with an auditor private key that is a private key corresponding to the auditor public key.
The workflow management system of claim 1 . the worker terminal further includes an audit request information generating unit that generates signed audit request information by signing information including the worker identification information and the auditor identification information, the information including identification information of a person who is authorized to access the information, with the worker private key;
The communication unit further transmits the signed audit request information to the workflow control device;
The blockchain management unit of the workflow control device further registers the signed audit request information in the blockchain.
The workflow management system of claim 2 . a communication unit of the workflow control device notifies the auditor terminal of a message indicating that an audit of the result of the work has been requested;
The inspector terminal includes:
an audit information acquisition unit that acquires the signed result information and the signed audit request information from the blockchain via the workflow control device upon receiving a notification regarding the audit request;
a signature verification unit that uses the worker public key acquired from the signature management device to verify whether or not the signatures of the signed result information and the signed audit request information are signatures affixed with the worker private key.
The workflow management system of claim 3 . The inspector terminal includes:
an audit information generating unit that generates signed audit information by signing information indicating an audit result of the work included in the signed result information, the information including identification information of a person who is authorized to access the information, with the auditor private key;
a confirmation request information generating unit that generates signed confirmation request information by signing information including the auditor identification information and the accessor identification information, the information including identification information of a person who is permitted to access the information, with the auditor private key; and
a communication unit that transmits the signed audit information and the signed verification request information to the workflow control device,
a blockchain management unit of the workflow control device registers the signed audit information and the signed verification request information in the blockchain;
The workflow management system of claim 4 . a communication unit of the workflow control device notifying the user terminal of a message indicating that a request for confirmation of the audit result has been received;
The reference terminal is
a confirmation information acquisition unit that acquires the signed audit information and the signed confirmation request information from the blockchain via the workflow control device upon receiving a notification regarding the confirmation request;
a signature verification unit that uses the auditor public key acquired from the signature management device to verify whether or not the signatures of the signed audit information and the signed verification request information are signatures affixed with the auditor private key.
The workflow management system of claim 5 . The reference terminal is
a confirmed information generating unit that generates signed confirmed information by signing information indicating a confirmation result of an audit, the information being included in the signed audit information and including identification information of a person who is authorized to access the information, with the accessor private key;
a communication unit that transmits the signed confirmed information to the workflow control device,
The blockchain management unit of the workflow control device registers the signed confirmation information in the blockchain.
The workflow management system of claim 6 . an access right setting unit of the access user terminal generates signed access permission information by signing information including identification information of a person who is permitted to access each of the signed result information and the signed audit information with the access user private key ;
The workflow management system of claim 7 .

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