Information and communication equipment and information and communication programs

Abstract

We provide information and communication devices that enable information sharing using blockchain technology on a peer-to-peer network. [Solution] The system includes a group information storage unit 12 that stores group information shared among members, a transaction issuing unit 18 that issues a transaction to the blockchain 4 indicating that a group information has been modified when one member performs a predetermined operation to change the content of a group information, a transmission unit 14 that sends the modified group information to other members, a transaction confirmation unit 20 that, upon detecting the receipt of other group information from other members, accesses the blockchain 4 and checks for the presence of other transactions indicating that other group information has been modified, and an update processing unit 22 that, if other transactions exist, reflects the other group information as valid information.

Description

Technical Field

[0001] The present invention relates to an information communication system and the like that realizes highly reliable groupware using blockchain.

Background Art

[0002] A technique for synchronizing data via the Internet is disclosed in Patent Document 1. In the technique shown in Patent Document 1, accounting data input by an accounting processing device is used as a primary accounting file. When a transmission instruction is given, the primary accounting file is used as an attached file and is attached to a transmission notification email and stored in a primary accounting file for each consulting destination of the accounting processing device via the Internet. After the correction is completed on the accounting processing device that displays the screen, when a synchronization instruction operation is performed, synchronization processing is performed between the received data of the primary accounting file and the official accounting file. After the synchronization processing is completed, the synchronized primary file is used as an attached file and is attached to a transmission notification email and stored in the primary accounting file of the accounting processing device via the Internet. After receiving the email, synchronization processing is performed between the received data of the primary accounting file and the official accounting file.

[0003] [[ID=第十五]] In addition, the inventor has developed a technique shown in Patent Document 2 as a technique for securing the legitimate transmission and reception of electronic data using blockchain. The technique shown in Patent Document 2 includes a mail transmission unit that transmits electronic data to another computer, and a remittance control unit that generates a remittance transaction for accessing the blockchain of digital currency and broadcasts it to the blockchain. As the mail transmission unit transmits electronic data, the remittance control unit generates a remittance transaction of digital currency related to the electronic data and broadcasts it to the blockchain. It also includes a mail reception unit that receives electronic data from another computer, and a reception control unit that accesses the blockchain to confirm the incoming status of digital currency from the sender of the electronic data and determines the reception of the electronic data according to the incoming status.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Patent No. 4817404 [Patent Document 2] Patent No. 6583841 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the technology shown in Patent Document 1 has a security vulnerability because it cannot authenticate the files that have been sent or received. Furthermore, while the technology shown in Patent Document 2 significantly reduces security risks through authentication, it cannot synchronize shared electronic data, making it insufficient as groupware.

[0006] Therefore, the present invention has been made to solve the above problems, and aims to provide an information communication device and information communication program that can function as groupware that can share information using blockchain on a peer-to-peer network without having a shared server. [Means for solving the problem]

[0007] The information communication device according to the present invention is an information communication device that is constructed by connecting peer to peer and constitutes an information communication system that functions a groupware using blockchain for managing group information shared among multiple members in a shareable state without having a shared server, wherein the information communication device is used individually by each of the members forming the group, and each member has a storage area reserved for storing the group information shared among those members, and when one member performs a predetermined operation to change the content of one group information in one storage area from one information communication device used by that member, a transaction indicating that the predetermined operation has been performed on the one group information is recorded. The system comprises: a transaction issuance means for issuing a transaction to the blockchain; a transmission means for sending the group information of one after the predetermined operation to other members; a transaction confirmation means for accessing the blockchain and checking for the existence of other transactions indicating that a predetermined operation has been performed by the other member to change the content of the group information of another storage area from another information communication device; and an update means for reflecting the group information of the other transmitted from the other information communication device as valid information in the group information of the one storage area corresponding to the other group information, when it is confirmed that there is a newly issued other transaction.

[0008] Thus, in the information communication device according to the present invention, when a predetermined operation is performed to change the content of group information stored in a storage area secured in the storage means, the change in the group information is authenticated by accessing the blockchain, and the received group information is reflected as legitimate group information on the condition that authentication is performed. In this way, the device has the effect of reliably sharing and managing group information while accurately determining whether the received group information is legitimate by accessing the blockchain. [Brief explanation of the drawing]

[0009] [Figure 1] This is a system configuration diagram of an information communication system using an information communication device according to the first embodiment of the present invention. [Figure 2] This is a functional block diagram showing the configuration that functions during information transmission in an information communication device according to the first embodiment of the present invention. [Figure 3] This figure shows the processing of the transaction issuing unit in an information communication device according to the first embodiment of the present invention. [Figure 4] This is a functional block diagram showing the configuration that functions when information is received in an information communication device according to the first embodiment of the present invention. [Figure 5] This figure shows the processing of the transaction confirmation unit in an information communication device according to the first embodiment of the present invention. [Figure 6] This flowchart illustrates the process of sending a shared file when a user edits a shared file located locally in an information communication device according to the first embodiment of the present invention. [Figure 7] This flowchart illustrates the process of receiving a shared file when a shared file located locally on another member's device is edited in an information communication device according to the first embodiment of the present invention. [Figure 8] This is a flowchart illustrating the transmission process when sharing an attachment to an email in an information communication device according to the first embodiment of the present invention. [Figure 9] This is a flowchart illustrating the receiving process when sharing an attachment sent via email in an information communication device according to the first embodiment of the present invention. [Figure 10] This is a flowchart illustrating the transmission process when an attachment to an email is shared on a shared server in an information communication device according to the first embodiment of the present invention. [Figure 11] This flowchart illustrates the receiving process when an attached file sent via email is shared on a shared server in an information communication device according to the first embodiment of the present invention. [Modes for carrying out the invention]

[0010] (First embodiment of the present invention) The information communication device according to this embodiment will be described with reference to Figures 1 to 11. The information communication device according to this embodiment is a device that operates groupware on a network constructed by peer-to-peer connections, enabling the sharing of group information among multiple members without the need for a shared server, and ensures the security of the shared group information by using blockchain.

[0011] In the following embodiments, shared servers include file sharing servers and authentication servers for implementing login functionality, while mail servers are not included as shared servers. Furthermore, a configuration without a shared server includes not only configurations without both a file sharing server and an authentication server, but also configurations without either a file sharing server or an authentication server. In addition, group information shared among multiple members includes, for example, shared files, shared messages, shared schedules, shared links, shared images (still and moving images), shared tasks, and shared meeting minutes.

[0012] Furthermore, the terms used in the following embodiments are defined as follows. (1) Blockchain It is a type of distributed database. Data is stored sequentially in units called blocks. Each block records the hash values ​​up to the previous block. This means that in order to tamper with the data midway through, it is necessary to calculate the hash values ​​for all the data following the block being tampered with. For this reason, tampering with blockchain data is difficult. (2) Digital Currency It is a virtual currency realized by blockchain technology. There are digital currencies with real monetary value in reality, such as the well-known Bitcoin and Ethereum, but there are also many digital currencies without monetary value. Due to blockchain technology, it is extremely difficult to counterfeit or replicate digital currencies. (3) Wallet It is a mechanism for storing or managing digital currencies. There are various forms, from web wallets stored online to cold wallets stored on terminals disconnected from the network. Users of digital currencies own digital currencies on the wallet, and the transfer and receipt of digital currencies are carried out between wallets. (4) Wallet Account It is an ID for identifying a wallet. Each user manages digital currencies with a unique wallet account. In the above-mentioned Bitcoin and Ethereum, the hash value of the public key is used as the wallet account. (5) Transaction It is the transaction data of digital currencies recorded on the blockchain. Generally, it is the data recording the transfer from one wallet account to another. The wallet account sending the digital currency signs and sends the transaction describing its own wallet account and the recipient's wallet account using its own private key, and then the transaction is issued. (6) Mining It is the work of summarizing a plurality of issued transactions into one block that can be recorded on the blockchain and recording it at the beginning of the blockchain. The wallet account performing this work is called a miner. By being recorded on the blockchain by the miner, the transaction history is determined in an unforgeable form. It takes several minutes from the issuance to the confirmation of the transaction. (7) Mail Send Coin (hereinafter referred to as MSC) A digital currency implemented in the present invention as a type of virtual currency, which is a type of digital currency that does not aim to have a monetary value and can be transferred together when sending an email.

[0013] FIG. 1 is a system configuration diagram of an information communication system using the information communication device according to the present embodiment. In FIG. 1, the information communication system 1 includes a communication network 3 constructed by a plurality of information communication devices 10 that are individually used by each member forming a group and are connected peer-to-peer, and a blockchain 4 that accumulates transactions broadcast from each of the information communication devices 10 and functions as a distributed database.

[0014] For example, assume that one information communication device 10 (hereinafter referred to as the first information communication device 10a) and another information communication device 10 (hereinafter referred to as the second information communication device 10b) are connected peer-to-peer and both hold the same file that one has previously sent to the other (hereinafter, this file is referred to as a shared file). In the information communication system 1 of FIG. 1, since it does not have a shared server, the shared file is held as the same file in the local storage areas of the first information communication device 10a and the second information communication device 10b, respectively. At this time, when the first member using the first information communication device 10a changes the shared file, the changed file is sent to the second information communication device 10b. At the same time, the first information communication device 10a broadcasts a transaction (hereinafter referred to as a change transaction) indicating that the shared file has been changed from the shared account of the first member of the first information communication device 10a to the shared account of the second member using the second information communication device 10b to the blockchain 4. Here, the shared account is identification information for identifying each member of the same group in groupware, and for example, a mail address, an ID of SNS, etc. may be used.

[0015] In addition, in a change transaction, the information indicating that MSC was sent from the first member's wallet account to the second member's wallet account may serve as proof that the shared file has been changed, or the information indicating that the first member made changes to the shared file may be recorded. In other words, it is sufficient to record the fact that the first member made changes to the shared file, the time, or the content of the changes in a way that can identify them (such as a change ID that uniquely identifies the changes). Specifically, for example, by sending the hash value of the shared file after the changes to Blockchain 4, it becomes possible to prove that the changes received via peer-to-peer transfer were indeed made by the first member.

[0016] The second information communication device 10b provisionally receives the shared file transmitted from the first information communication device 10a. Provisional reception here refers to a state where, for example, the information has been received but is not displayed to the receiving member (i.e., the changes to the group information, as described later, have not been reflected), or a state where only a notification that the shared file has been changed (or sent after the change operation) has been received, but the shared file itself has not yet been received. When the second information communication device 10b provisionally receives the shared file, it accesses blockchain 4 and checks for the existence of the above change transaction. If it is confirmed that the above change transaction exists on blockchain 4, it receives the provisionally received shared file as the legitimate latest shared file (if only a notification has been received, it sends information to the first information communication device 10a indicating that it is possible to receive it as a legitimate shared file, and receives the changed shared file transmitted from the first information communication device 10a), and overwrites the shared file stored in the local storage area of ​​the second information communication device 10b.

[0017] Furthermore, when the first information communication device 10a transmits the shared file, it transmits it in an encrypted state using the public key of the second member using the second information communication device 10b, which is the recipient, i.e., the wallet account used as the public key as described above. When the second information communication device 10b receives the encrypted shared file as a legitimate shared file, it decrypts it using the private key of the second member that corresponds to the public key of the second member. This makes it possible to authenticate the source of the shared file using blockchain 4, and to ensure the confidentiality and security of the transmitted shared file.

[0018] Figure 2 is a functional block diagram showing the configuration that functions when transmitting information in the information communication device according to this embodiment. In Figure 2, the information communication device 10 includes an operation unit 11 that performs processing on group information stored in the group information storage unit 12 in accordance with the operation performed by the member, an encryption processing unit 13 that encrypts the target data that has been operated on by the operation unit 11 using a public key (wallet account) stored in the public key information storage unit 16, a transmission unit 14 that transmits the encrypted target data to an account stored in the shared account information storage unit 17 using the communication network 3, and a transaction issuing unit 18 that, upon receiving the operation performed by the operation unit 11, reads the wallet account information of the member who shares the target data from the public key information storage unit 16, generates a change transaction indicating that the member has changed the group information, and signs the generated change transaction using the private key information stored in the private key information storage unit 15 and broadcasts it to the BC (blockchain) 4.

[0019] Each component will be explained in detail. The group information storage unit 12 stores group information shared among members of the same group in the groupware. This group information stores various shared information such as shared files and shared schedules as described above. When a member who is a user of the information communication device 10 performs an operation to modify the group information stored in the group information storage unit 12, such as adding, updating, and / or deleting, using an input device such as a keyboard, mouse, touch panel, or microphone, the operation unit 11 executes the group information modification process (including processing associated with the modification of the group information, such as the operation to send the modified group information) based on the input signal. In addition, upon receiving the group information modification process from the operation unit 11, the transaction issuance unit 18 performs the modification transaction issuance process.

[0020] Here, the processing of the transaction issuing unit 18 will be explained. Figure 3 is a diagram showing the processing of the transaction issuing unit in the information communication device according to this embodiment. The public key information storage unit 16 stores a wallet account, which is identification information necessary for accessing the blockchain 4, for each member of the same group in the groupware. Since this wallet account information is the hash value of each member's public key, it has the function of identifying the public key. The shared account information storage unit 17 stores a shared account, which is identification information for each member of the same group in the groupware. These wallet accounts and shared accounts are stored in a one-to-one correspondence. The transaction issuing unit 18 extracts the corresponding wallet account from its own shared account, and also extracts all corresponding wallet accounts from the shared accounts of all shared members who share the target data that has been modified. Using these wallet accounts, a transaction is created as a modification transaction that indicates that MSC will be sent from the member who performed the modification processing from the operation unit 11 to other shared members.

[0021] In addition, users may register their shared accounts and corresponding wallet accounts in advance in the public key information storage unit 16 and the shared account information storage unit 17, or they may provide a separate dedicated storage means.

[0022] Furthermore, if the wallet account of a shared member is unknown, the system may first request the shared member's public key from blockchain 4 and obtain the public key information. The obtained public key information is stored in the public key information storage unit 16, and subsequent processing does not require requests to blockchain 4.

[0023] Once a modification transaction is created, the user signs the modification transaction with their private key stored in the private key information storage unit 15, broadcasting the created modification transaction to blockchain 4 and writing MSC remittance information (i.e., information indicating that the member who performed the modification has modified the target data of the group information) to blockchain 4. Since tampering with blockchain 4 is extremely difficult, the remittance information written here is highly reliable and can therefore function as highly reliable information that proves that a modification has been performed on the target data.

[0024] Returning to Figure 2, while the transaction issuing unit 18 creates the modification transaction, (or before or after), the encryption processing unit 13 encrypts the modified data using the public keys of the shared members stored in the public key information storage unit 16. That is, if there are multiple shared members, each member's data is encrypted individually with their corresponding public key. Then, each of these encrypted target data is sent by the transmission unit 14 to the account of the respective shared member.

[0025] Figure 4 is a functional block diagram showing the configuration that functions when information is received in the information communication device according to this embodiment. In Figure 4, the information communication device 10 includes a temporary receiving unit 19 that receives the modified target data (the target data received here is encrypted with its own public key as described above) when another shared member modifies the group information stored in the group information storage unit 12 and sends it to each shared member; a transaction confirmation unit 20 that, upon receiving the target data from the temporary receiving unit 19, reads the wallet account corresponding to the account of the other shared member who sent the data from the public key information storage unit 16, queries the blockchain 4 to confirm whether or not there is a modification transaction issued by the wallet account; a decryption processing unit 21 that, if it is confirmed that there is a modification transaction on the blockchain 4, decrypts the target data received by the temporary receiving unit 19 with its own private key stored in the private key information storage unit 15; and an update processing unit 22 that updates the target data in the group information storage unit 12 with the decrypted target data.

[0026] Each configuration will be explained in detail. The temporary receiving unit 19 receives the target data after other shared members have made changes to the group information, but at this stage it has not been confirmed that it is legitimate target data (target data whose sender is guaranteed), so it is in a state of temporary reception. This temporary reception includes, for example, a state in which the target data itself has been received but is temporarily stored in a memory area that cannot be accessed by the member's operations, or a state in which only a prior notification that the target data will be sent (for example, a message such as "Target data has been changed by member XX") has been received but the target data itself has not yet been sent, or, in the case of the target data being an email, a state in which it remains on the email receiving server.

[0027] When the temporary receiving unit 19 receives data as described above, the transaction confirmation unit 20 confirms the change transaction. Figure 5 shows the processing of the transaction confirmation unit in the information communication device according to this embodiment. In Figure 5, the transaction confirmation unit 20 extracts the corresponding wallet account from the account of another shared member that sent the target data temporarily received by the temporary receiving unit 19, based on the public key information storage unit 16 and the shared account information storage unit 17. It also extracts the corresponding wallet account from its own shared account. From these extracted wallet accounts, it queries the blockchain 4 to check whether there are any change transactions from the wallet accounts of other shared members to its own wallet account. If it is confirmed that there are change transactions, it proceeds to the decryption processing unit 21 based on that confirmation information. If there are no change transactions, the temporary receiving unit 19 either ignores the temporary reception, deletes the temporarily received target data, or queries the sender based on that confirmation information.

[0028] In this case as well, the user's shared account and corresponding wallet account may be registered in advance in the public key information storage unit 16 and the shared account information storage unit 17, or a separate dedicated storage means may be provided.

[0029] Furthermore, if the wallet account of a shared member is unknown, the system may first request the shared member's public key from blockchain 4 and obtain the public key information. The obtained public key information is stored in the public key information storage unit 16, and subsequent processing does not require requests to blockchain 4.

[0030] Returning to Figure 4, once the transaction confirmation unit 20 confirms that there is a modification transaction, the temporary receiving unit 19 determines that the temporarily received target data is legitimate target data modified by another shared member, and the decryption processing unit 21 decrypts the temporarily received target data using its own private key stored in the private key information storage unit 15. In other words, as explained in the block diagram of Figure 2, the target data sent from other shared members is encrypted using one's own public key (wallet account information), and can be decrypted using the corresponding private key.

[0031] The update processing unit 22, having confirmed by the transaction verification unit 20 that the decrypted target data is reliable and that it has been modified by other shared members, overwrites the target data in the group information storage unit 12 as valid group information. This allows members to share synchronized group information.

[0032] Next, the processing of the information communication device 10 in the above configuration will be described. Figure 6 is a flowchart showing the process of sending a shared file when a shared file located locally on the user's local machine is edited in the information communication device according to this embodiment, and Figure 7 is a flowchart showing the process of receiving a shared file when a shared file located locally on another member's local machine is edited in the information communication device according to this embodiment. Figures 6 and 7 show the processing flow of operations that take place between a general groupware installed on the information communication device 10, an add-in that extends the functionality of the groupware (the add-in contains a shared area), the blockchain 4, and the user.

[0033] First, in Figure 6, the user specifies a file they want to share (hereinafter referred to as a shared file) to the groupware using the functions of the operation unit 11. Alternatively, if the file is already shared, the user specifies that shared file (S1). When the target shared file is specified, the add-in retrieves the shared file (S2), saves (adds) the shared file to the group information storage unit 12, which is the file sharing area within the add-in, or overwrites an existing shared file with an edited version (S3). The add-in's transaction issuing unit 18 detects that a predetermined operation (for example, an operation to change group information by adding or editing a shared file) has been performed on the shared file by the operation unit 11, and issues a change transaction to the blockchain 4 using the process described above in Figure 3 (S4). The add-in's encryption processing unit 13 also encrypts the retrieved shared file using the public keys of other members who plan to share (or have already shared) the shared file (S5). The add-in returns the encrypted shared file to the groupware (S6), and the groupware's transmission unit 14 sends the encrypted shared file to other members who share the file (S7), and then terminates the transmission process.

[0034] If an encrypted shared file is sent from another member, the flow shown in Figure 7 below is executed. In Figure 7, the temporary receiving unit 19 of the groupware receives the shared file (temporarily receives) (S1) depending on whether the user operates the groupware or the method of acquiring shared information pre-configured in the groupware. When the add-in acquires the shared file received by the temporary receiving unit 19 (S2), the transaction confirmation unit 20 checks for the presence of a change transaction against the blockchain 4 using the process described above in Figure 5 (S3). If it is confirmed that there is a change transaction, the decryption processing unit 21 decrypts the shared file encrypted with its public key using its private key (S4), and the update processing unit 22 saves (adds) or overwrites the decrypted shared file in the group information storage unit 12, which is the file sharing area within the add-in (S5). At the same time, the decrypted shared file is returned to the groupware (S6), the groupware displays the shared file (S7), and the receiving process ends.

[0035] As shown in the flowcharts in Figures 6 and 7, in this case, it becomes possible to share local group information (shared files) among group members securely and confidentially without having both a file sharing server and an authentication server.

[0036] Figure 8 is a flowchart showing the transmission process when sharing an attachment attached to an email in the information communication device according to this embodiment, and Figure 9 is a flowchart showing the reception process when sharing an attachment sent via email in the information communication device according to this embodiment. In Figures 8 and 9, a general email sending and receiving software (hereinafter referred to as "mailer") installed on the information communication device 10 is used as groupware, and the processing flow of the process that takes place between an add-in that extends the functionality of the mailer, the blockchain 4, and the user.

[0037] First, in Figure 8, the user performs a send operation using the functions of the operation unit 11 to send an email and attachments to that email using the mailer (S1). The add-in temporarily stops the sent process (S2) and retrieves the email and attachments (S3). At this time, the email body and attachments may be saved in the group information storage unit 12, which is a file sharing area within the add-in, as shown in Figure 6, or the user may save them in a local area of ​​their choice. The transaction issuing unit 18 of the add-in, upon receiving confirmation from the operation unit 11 that an email with attachments has been sent, issues a change transaction to the blockchain 4 using the process described above in Figure 3 (S4). The encryption processing unit 13 of the add-in then encrypts the retrieved email and attachments using the public key of the recipient member to whom the email is being sent (S5). The add-in returns the encrypted email and attachments to the mailer's sending unit 14 (S6). The sending unit 14 sends the encrypted email and attachments to the mail server (S7) and terminates the process.

[0038] In Figure 8, we explained the case where both the email and the attachment are encrypted. However, if confidentiality is not required for the email body, only the attachment may be encrypted, and if confidentiality is not required for the attachment, only the email body may be encrypted.

[0039] If encrypted emails and attachments are sent from other members, the flow shown in Figure 9 below is executed. In Figure 9, depending on whether the user operates the mailer or the automatic email retrieval setting configured in the mailer, the mailer's temporary receiving unit 19 checks the mail server for the presence of received emails and attachments and performs temporary retrieval (S1). This temporary retrieval may involve downloading the temporarily received emails and attachments into the add-in, or leaving them on the mail server. When the add-in detects the temporary retrieval of emails by the temporary receiving unit 19 (S2), it retrieves the emails and attachments (S3). Once the add-in retrieves the emails and attachments, the transaction confirmation unit 20 checks the blockchain for the presence of modification transactions using the process described above in Figure 5 (S4). Once it is confirmed that there is a change transaction, the decryption processing unit 21 decrypts the email and attachments encrypted with its public key, which were temporarily received by the temporary receiving unit 19 or the mail server, using its private key (S5). The update processing unit 22 returns the decrypted email and attachments to the mailer and saves the attachments to the group information storage unit 12 (S6). The mailer displays the email and attachments (S7) and terminates the receiving process.

[0040] As shown in the flowcharts in Figures 8 and 9, in this case as well, it is possible to share emails and attachments as group information without having both a file sharing server and an authentication server. In other words, it becomes possible to share group information (sending and receiving emails and attachments) among members in a secure and confidential manner without sharing passwords or performing authentication such as login in advance.

[0041] Figure 10 is a flowchart showing the transmission process when an attachment to an email is shared on a shared server in the information communication device according to this embodiment, and Figure 11 is a flowchart showing the reception process when an attachment sent by email is shared on a shared server in the information communication device according to this embodiment. Figures 10 and 11 show the processing flow of operations that take place between the mailer installed on the information communication device 10, an add-in that extends the functionality of the mailer, a blockchain, a file sharing server that is generally provided as an external storage service, and the user.

[0042] First, in Figure 10, the user performs a send operation using the functions of the operation unit 11 to send an email and the attachments to that email via a mailer (S1). The add-in temporarily stops the sent process (S2) and retrieves the email and attachments (S3). At this time, the email body and attachments may be saved in the group information storage unit 12, which is a file sharing area within the add-in, as in the case of Figure 8, or the user may save them in a local area of ​​their choice. The transaction issuing unit 18 of the add-in, upon receiving confirmation from the operation unit 11 that an email with attachments has been sent, issues a change transaction to the blockchain 4 using the process described above in Figure 3 (S4). The encryption processing unit 13 of the add-in then encrypts the retrieved attachments using the public keys of the members to whom the email is being sent (S5). The upload unit (not shown in Figure 2) of the add-in uploads the encrypted attachments to the file sharing server (S6) and retrieves the link information of the upload destination (S7). The upload unit returns the acquired link information and email to the mailer's sending unit 14 (S8). The sending unit 14 sends an email containing the link information for uploading the attachment to the mail server (S9), and then terminates the process.

[0043] If another member sends an email containing a link to an attachment, the flow shown in Figure 11 below is executed. In Figure 11, the temporary receiving unit 19 of the mailer checks with the mail server for the presence of an email, either by the user operating the mailer or according to the automatic email retrieval setting configured in the mailer, and receives the email containing the link to the attachment (S1). When the add-in detects the temporary reception of the email by the temporary receiving unit 19 (S2), it retrieves the email containing the link to the attachment (S3). The transaction confirmation unit 20 checks with the blockchain for the presence of a change transaction using the process described above (S4). If it is confirmed that there is a change transaction, the download unit of the add-in (not shown in Figure 4) accesses the link in the email (S5) and downloads the attachment (S6). The download unit returns the downloaded attachment to the decryption processing unit 21, which decrypts the attachment, which is encrypted with its public key, using its private key (S7). The update processing unit 22 returns the decrypted attachment to the mailer and saves the attachment to the group information storage unit 12 (S8). The mailer displays the email and attachment (S9) and terminates the reception process.

[0044] Although the upload and download sections are add-in functions, the mailer's sending section 14 and temporary receiving section 19 may also perform these functions. In other words, since the mailer and the add-in function as a single unit, there is no need to clearly distinguish them in terms of configuration, and the sending section 14 may function as the upload section, or the temporary receiving section 19 may function as the download section.

[0045] As shown in the flows in Figures 10 and 11, in this case, it is possible to share group information on a file sharing server without having an authentication server. In other words, since there is no need to perform authentication such as logging in, there is no need to share passwords in advance, and it is possible to share group information (sending and receiving attachments) with security and confidentiality guaranteed on a file sharing server that can be accessed by an unspecified number of people.

[0046] Thus, in the information communication device 10 according to this embodiment, the information communication device 10 is configured to function as an information communication system 1 that uses blockchain 4 to operate groupware for managing group information shared among multiple members in a shareable state without having a shared server, which is constructed by connecting peer to peer, and the information communication device 10 is used individually by each member forming a group, and includes a group information storage unit 12 for which a storage area is secured for storing group information shared among members, a transaction issuing unit 18 that issues a transaction to blockchain 4 indicating that a predetermined operation has been performed on a group information when a member performs a predetermined operation to change the content of a group information in a storage area from an information communication device 10 used by that member, a transmission unit 14 that transmits the group information after the predetermined operation to other members, and when it detects the receipt of other group information from other members, The system includes a transaction confirmation unit 20 that accesses blockchain 4 and checks for the presence of other transactions indicating that a predetermined operation has been performed by another member to change the content of other group information in another storage area from another information communication device 10, and an update processing unit 22 that, if it is confirmed that there is a newly issued other transaction, reflects the other group information transmitted from the other information communication device 10 as valid information in the group information in one storage area corresponding to the other group information. Therefore, when a predetermined operation to change the content of group information is performed, the system authenticates that the group information has been changed by accessing blockchain 4, and, conditional on authentication, reflects the received group information as valid group information. Thus, without having both a file sharing server and an authentication server, the system can reliably share and manage group information peer-to-peer, and accurately determine whether the received group information is valid by accessing blockchain 4.

[0047] Furthermore, if necessary, the information communication device 10 includes an encryption processing unit 13 that encrypts the group information of one member after a predetermined operation with a public key corresponding to the blockchain account of another member who shares the group information, and a decryption processing unit 21 that decrypts the received group information with a private key held by that member and corresponding to the blockchain account of that member. Thus, by utilizing the mechanism of blockchain 4, the sending and receiving of group information can be performed while maintaining confidentiality using public-key cryptography.

[0048] Furthermore, if necessary, the group information is information about an email and / or information about an attachment attached to that email. The transaction issuing unit 18 issues a transaction to the blockchain 4 indicating that a sending operation has been performed when one member sends an email and / or attachment, which is group information, to another member. The sending unit 14 sends the email and / or attachment, which is group information, to the other member's email address. The transaction confirmation unit 20, upon confirmation that an email and / or attachment has been sent by another member, accesses the blockchain 4 to check for the existence of other transactions indicating that another member has performed a sending operation to send an email and / or attachment, which is other group information, to one member. The update processing unit 22, upon confirmation that there are other newly issued transactions, stores the email and / or attachment, which is other group information, as valid information in a storage area and reflects it. Thus, emails and attachments can be sent and received while maintaining confidentiality, and the sender and recipient can be authenticated by the blockchain 4.

[0049] Furthermore, if necessary, the group information is the information of an attachment attached to an email, and the transaction issuing unit 18 issues a transaction to the blockchain 4 indicating that a sending operation has been performed when one member sends an attachment containing group information to another member, the sending unit 14 uploads the attachment containing group information to an external storage shared with other members and sends a link information indicating the location of the attachment in the external storage to the email address of the other member via email, and the transaction confirmation unit 20, upon receiving the link information from the other member via email, confirms the transaction on the blockchain 4. The system checks for other transactions indicating that other members have performed a sending operation to send an attached file containing other group information to one member. If the update processing unit 22 confirms that there are other newly issued transactions, it accesses the external storage indicated by the link information received via email, downloads the attached file as legitimate information to the storage area, and reflects it there. This makes it possible to share group information on a file sharing server peer-to-peer without an authentication server, and since there is no need to perform authentication such as logging into the file sharing server, it becomes possible to share group information with security and confidentiality guaranteed on a file sharing server that can be accessed by an unspecified number of people.

[0050] Furthermore, if necessary, the group information is shared information stored in a storage area reserved in a local group information storage unit 12 within the information communication device 10 used individually by each member. The transaction issuing unit 18 issues a transaction to the blockchain 4 indicating that a change operation has been performed when a member changes the content of a group information stored in a storage area. The transmission unit 14 sends the changed group information to other members. The transaction confirmation unit 20 accesses the blockchain 4 when it is confirmed that another member has changed the content of another group information stored in another storage area, and checks for the existence of other transactions indicating that the other member has changed the other group information. The update processing unit 22, when it is confirmed that there is a newly issued other transaction, reflects the other group information transmitted from another information communication device 10 as valid information in the group information in the storage area corresponding to that other group information. Thus, it becomes possible to share locally stored group information among members securely and confidentially in a peer-to-peer manner without having both a file sharing server and an authentication server. [Explanation of symbols]

[0051] 1. Information and communication systems 3. Communication Network 4. Blockchain (BC) 10. Information and communication equipment 11 Control section 12 Group Information Storage Unit 13. Encryption Processing Unit 14. Transmitter 15 Private key information storage unit 16. Public Key Information Storage Unit 17. Shared Account Storage 18 Transaction Issuance Department 19 Temporary receiving unit 20 Transaction Verification Section 21 Decoding Processing Unit 22 Update Processing Unit

Claims

1. An information and communication device that constitutes an information and communication system that uses blockchain to enable the functioning of groupware for managing group information shared among multiple members, which is built using peer-to-peer connections, without the need for a shared server. The aforementioned information and communication devices are to be used individually by each of the members forming the group. A storage means is provided in which a storage area is secured for each of the members to store the group information shared among those members, A transaction issuing means that issues a transaction to the blockchain indicating that a predetermined operation has been performed on a group of information in a storage area when a member performs a predetermined operation to change the contents of a group of information in a storage area from an information communication device used by that member. A transmission means for transmitting the group information after the predetermined operation to other members, Transaction confirmation means that, upon detecting the receipt of other group information from the other member, accesses the blockchain and checks for the presence of other transactions indicating that a predetermined operation has been performed by the other member to modify the contents of other group information in another storage area from another information communication device, An information communication device characterized by comprising an update means for reflecting, when it is confirmed that there is a newly issued other transaction, the other group information transmitted from the other information communication device as valid information in the group information in the one storage area corresponding to the other group information.

2. In the information communication device described in claim 1, The aforementioned information and communication device An encryption means for encrypting the group information after the predetermined operation using a public key corresponding to the blockchain account of another member who shares the group information, An information communication device characterized by comprising a decryption means for decrypting the received other group information with a private key corresponding to the blockchain account of the member held by that member.

3. In the information communication device according to claim 1 or 2, The group information is information about an email and / or information about an attachment to that email. The transaction issuing means issues a transaction to the blockchain indicating that a transmission operation has been performed when one member performs a transmission operation to send the email and / or attachment, which are the group information of the first member, to the other members. The transmission means sends the email and / or attachment, which is the group information, to the email address of the other member. When the transaction confirmation means confirms that the email and / or attachment has been sent by the other member, it accesses the blockchain and checks for the existence of other transactions indicating that the other member performed the sending operation to send the email and / or attachment, which is other group information, to the one member. The update means is characterized in that, when it is confirmed that there is another newly issued transaction, it stores and reflects the other group information, which is the email and / or the attached file, in the one storage area as valid information.

4. In the information communication device according to claim 1 or 2, The aforementioned group information is the information of an attachment to an email, The transaction issuing means issues a transaction to the blockchain indicating that a transmission operation has been performed when one member performs a transmission operation to send the attached file, which is the group information of one, to the other members. The transmission means uploads the attached file, which is the group information, to an external storage shared with the other members, and sends a link information indicating the location of the attached file in the external storage to the email address of the other members via email. When the transaction confirmation means receives the link information from the other member via email, it accesses the blockchain and checks for the existence of other transactions indicating that the other member performed the sending operation to send the attachment, which is the other group information, to the one member. The update means is characterized in that, when it is confirmed that there is another newly issued transaction, it accesses the external storage indicated by the link information received in the email, and downloads the attached file as valid information to the first storage area and reflects it there.

5. In the information communication device according to claim 1 or 2, The group information is shared information stored in the storage area reserved in the local storage means within the information communication device used individually by each member. The transaction issuing means issues a transaction to the blockchain indicating that a modification operation has been performed when a member modifies the contents of the group information stored in the storage area. The transmission means transmits the modified group information to the other members. The transaction confirmation means, upon confirmation that the content of the other group information stored in the other storage area has been changed by the other member, accesses the blockchain and checks for the existence of other transactions indicating that the other member has changed the other group information. The update means is characterized in that, when it is confirmed that there is a newly issued other transaction, it reflects the other group information transmitted from the other information communication device as valid information in the group information in the one storage area corresponding to the other group information.

6. An information and communication program installed on an information and communication device that constitutes an information and communication system that uses blockchain to enable the management of group information shared among multiple members, built through peer-to-peer connections, without the need for a shared server. A transaction issuing means that issues a transaction to the blockchain indicating that a predetermined operation has been performed on a group of information when a member performs a predetermined operation to change the content of a group of information in a storage area of ​​a storage means that has a storage area reserved for storing the group of information. A transmission means for transmitting the group information of one member after the predetermined operation to other members. Transaction confirmation means that, upon detecting the receipt of other group information from the other member, accesses the blockchain and checks for the presence of other transactions indicating that a predetermined operation has been performed by the other member to modify the contents of other group information in another storage area from another information communication device. An information communication program characterized in that, when it is confirmed that there is a newly issued other transaction, the computer functions as an update means for reflecting the other group information transmitted from the other information communication device as valid information in the group information in the one storage area that stores the other group information.

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