Information communication system and information communication device

Abstract

To provide an information communication system, device, and program capable of identifying an account of a user who is a SPAMer and suppressing a SPAM email by evaluating a user's accounts based on a deposit and withdrawal status of a virtual currency associated with sending and receiving the email.SOLUTION: When sending an email, the information communication system generates a remittance transaction that sends a predetermined amount of virtual currency to the recipient's account, broadcasts it on a blockchain 12. When receiving an email, if it is determined to be a legitimate email, the information communication system generates a refund transaction that restores the virtual currency deposited to the sender's account and broadcasts it on the blockchain 12. The information communication system includes a MARA platform 50 that evaluates the target account based on score values calculated by analyzing the deposit and withdrawal status of the virtual currencies stored on blockchain 12 for each user account of the information communication system.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an information and communication system that prevents spam attacks in e-mails. [Background technology]

[0002] Email received from unwanted recipients (hereafter referred to as "SPAM email") and the mail servers / mail accounts that send this SPAM email (hereafter referred to as "SPAMers") are a nuisance to most email users. According to a survey on SPAM email conducted by Symantec in March 2009 ("The State of Spam A Monthly Report - March 2009"), approximately 86% of emails distributed worldwide are SPAM emails. To prevent spam emails from spammers, methods include blacklisting email sending servers with specific IP addresses to restrict emails (Christian J. Dietrich, Christian Rossow, Empirical research of IP blacklists, ISSE 2008 Securing Electronic Business Processes, pp.163-171), (“SPAM DATABASE LOOKUP” DNSBL.info “https: / / www.dnsbl.info / ” (reference: 2023-12-25).), blacklisting specific email sending accounts (email addresses) to restrict email reception, and Yahoo! Mail and other services have their own spam filtering capabilities (“Yahoo!'s spam countermeasures”, YAHOO! JAPAN Mail. https: / / mail.yahoo.co.jp / antispam / (reference: 2023-12-25).).

[0003] However, these methods have the risk of false positives, making it difficult to prevent spam. The reason for this is a problem with the algorithms used to identify the above-mentioned mail sending servers and mail accounts as spammers. Generally, mail sending servers and mail accounts that send a large volume of e-mails that are determined to be spam are identified as spammers, but because they are only identified as spammers after sending a large volume of spam, they are unable to prevent spam before it occurs. In other words, there is a need for an algorithm that can identify spammers before sending a large volume of spam, or when they have sent less than a certain number of e-mails.

[0004] Furthermore, taking the above background into consideration, Patent Document 1 and Non-Patent Document 1 disclose technologies relating to measures against SPAM emails. The technologies disclosed in Patent Document 1 and Non-Patent Document 1 include an email sending unit that sends electronic data to other computers, and a remittance control unit that generates a remittance transaction for accessing a digital currency blockchain and broadcasts it to the blockchain, and as the email sending unit sends the electronic data, the remittance control unit generates a digital currency remittance transaction related to the electronic data and broadcasts it to the blockchain.

[0005] In Patent Document 1 and Non-Patent Document 1, email accounts are associated with blockchain accounts, and spam emails are suppressed by requiring all email senders, including spammers who send emails to an unspecified number of people, to remit virtual currency to the email recipient's blockchain account. This prevents spam emails on an email account basis, so even if general users and spammers use the same sending server, spam emails from spammers can be suppressed.

[0006] Furthermore, in conventional methods, after a spam email is generated, incoming messages from that sending server are rejected, so by changing the sending server, it is possible to send further spam emails. In Patent Document 1 and Non-Patent Document 1, unless virtual currency is obtained by some means, changing the sending server does not allow spam emails to be sent. Furthermore, from the virtual currency transaction history, which shows which blockchain account sent the money to which blockchain account, it is possible to obtain the sending and receiving history, which shows which email account sent the email to which email account. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6583841 [Non-patent literature]

[0008] [Non-Patent Document 1] K. Nakayama, Yutaka Moriyama, C. Oshima, An Algorithm that Prevents SPAM Attacks using Blockchain, 2018. Summary of the Invention [Problem to be solved by the invention]

[0009] As mentioned above, various proposals have been made to eliminate spam emails, which can be broadly categorized into three types: the first is a method that judges spam by inspecting the email content, the second is a method that judges spam based on the communication session, and the third is forcing costs on SMTP connections. As such, while there has been much progress in spam countermeasures, traditional methods still have some problems and issues, such as false positives and omissions.

[0010] The present invention has been made to solve the above-mentioned problems, and aims to provide an information and communications system that can identify user accounts that are spammers and suppress SPAM emails by evaluating the user's account based on the deposit and withdrawal status of virtual currency associated with sending and receiving emails. [Means for solving the problem]

[0011] The information and communication system of the present invention generates, when sending an email, a remittance transaction to send a specified virtual currency to a destination account in conjunction with the sending of the email, and broadcasts this to the blockchain; when receiving the email, if the email is determined to be a legitimate email, generates a refund transaction to refund the virtual currency that was deposited in conjunction with receiving the email to the sender's account as is, and broadcasts this to the blockchain; and is equipped with an evaluation means that analyzes the deposit and withdrawal status of the virtual currency stored in the blockchain for each target account of a user of the information and communication system, calculates a score value, and evaluates the target account based on the score value.

[0012] In this way, in the information and communications device of the present invention, when sending an email, a remittance transaction is generated to transfer a specified virtual currency to the recipient's account in conjunction with the sending of the email, and this is broadcast to the blockchain; when receiving the email, if the email is determined to be a legitimate email, a refund transaction is generated to refund the virtual currency that was deposited in conjunction with the receipt of the email directly to the sender's account, and this is broadcast to the blockchain.In this information and communications system, the deposit and withdrawal status of the virtual currency stored in the blockchain is analyzed for each target account of a user of the information and communications system to calculate a score value, and the target account is evaluated based on this score value, thereby evaluating the accounts of system users based on the deposit and withdrawal status of virtual currency, and as a result, it is possible to identify user accounts that are spammers and suppress SPAM emails. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a system overview diagram of an information communication system according to a first embodiment of the present invention. [Figure 2] FIG. 10 is an image diagram of a network graph created from email transmission information. [Figure 3] This is an image diagram of a network graph created from nodes and edges based on virtual currency deposit and withdrawal information. [Figure 4] FIG. 2 is an image diagram of a network graph that is actually generated in the information communication system according to the first embodiment of the present invention. [Figure 5] 1 is a functional block diagram showing a configuration of an information communication device in an information communication system according to a first embodiment of the present invention. [Figure 6] 6 is a diagram showing an example of information stored in a correspondence information storage unit appearing in FIG. 5. FIG. [Figure 7] FIG. 6 is a diagram illustrating the processing of a reception control unit in FIG. 5. [Figure 8]FIG. 6 is a diagram illustrating a process in which the MARA calculation unit in FIG. 5 creates a network graph and executes an algorithm. [Figure 9] FIG. 6 is a diagram illustrating a process in which the MARA calculation unit in FIG. 5 creates a network graph. [Figure 10] 4 is a flowchart showing a process performed when sending an e-mail in the information communication device according to the first embodiment of the present invention. [Figure 11] 5 is a flowchart showing a process performed when an email is received in the information communication device according to the first embodiment of the present invention. [Figure 12] 5 is a flowchart showing a refund process in the information communication device according to the first embodiment of the present invention. [Figure 13] 5 is a flowchart showing an evaluation process in the information communication device according to the first embodiment of the present invention. [Figure 14] FIG. 10 is a diagram showing parameters used in a simulation in an example. [Figure 15] 10 is an NS chart showing the main routine of a simulation for verifying the accuracy of spammer determination in an embodiment. [Figure 16] FIG. 10 is a diagram showing the results of a simulation for verifying the accuracy of spammer detection in an embodiment. [Figure 17] 10 is an NS chart showing the main routine of a simulation for verifying the suppression of SPAM mail in an embodiment. [Figure 18] FIG. 10 is a first diagram showing the results of a simulation for verifying the suppression of SPAM mail in the embodiment. [Figure 19] FIG. 10 is a second diagram showing the results of a simulation for verifying the suppression of SPAM mail in the embodiment. [Figure 20] FIG. 10 is a third diagram showing the results of a simulation for verifying the suppression of SPAM mail in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] (First embodiment of the present invention) An information communication system according to this embodiment will be described with reference to Figs. 1 to 13. The information communication system 1 according to this embodiment uses the SPAM Attack Guard Algorithm using Block Chain (hereinafter referred to as SAGA) developed by the inventors. BC This system uses the SAGA BC The basic concept and system configuration are as described in Patent Document 1 and Non-Patent Document 1 above.

[0015] SAGA BC In the system 100, the cost of sending emails is mutually paid using virtual currency (digital currency) to prevent spam attacks. Generally, when legitimate emails are sent to legitimate email addresses, the emails are legitimately received, so the number of emails sent matches the number of emails received. On the other hand, many of the emails sent in large quantities by spammers to random addresses are not legitimately received. Therefore, the number of emails sent by spammers does not match the number of emails received.

[0016] SAGA BC System 100 focuses on the difference between the number of emails sent and the number of emails received, and uses blockchain technology to pay the cost of sending emails with virtual currency, which is returned if the email is received properly. In other words, normal users who send emails that are received properly do not incur any virtual currency costs under this system, but users such as spammers who send large volumes of emails that are not received properly must pay the cost of replenishing their virtual currency. As a result, it is possible to prevent spam attacks by spammers.

[0017] Here, definitions of terms used in this embodiment are provided below. A "blockchain" is a type of distributed database that stores data sequentially in units called blocks. Each block records hash values ​​up to the block immediately preceding it. This makes it difficult to tamper with data in a blockchain, since in order to tamper with data midway, it is necessary to calculate hash values ​​for all data following the block to be tampered with.

[0018] "Virtual currency" is a digital currency realized by blockchain technology. Commonly known virtual currencies include Bitcoin (Reference: S. Nakamoto, Bitcoin: A Peer-to-peer Electronic Cash System. 2008.) and Ethereum (Reference: GJ Wood, Ethereum: A Secure Decentralized Generalized Transaction Ledger, Ethereum project yellow paper, 151, pp. 1-32, 2014.), which have actual monetary value, but there are also many virtual currencies that have no value. Blockchain technology has made it possible to create virtual currencies that are difficult to counterfeit or replicate.

[0019] "Wallet" is a general term for a mechanism for managing virtual currencies. There are various types, from web wallets that store virtual currencies online to cold wallets that store virtual currencies on devices that are isolated from the computer network. Virtual currency users manage their virtual currencies in wallets, and sending and receiving virtual currencies is carried out between wallets (Reference: A. Hayes, What factors give cryptocurrencies their value: An empirical analysis. 2015.).

[0020] A "wallet account" is an ID that identifies a blockchain wallet. Each user manages virtual currency through a unique wallet account. In Bitcoin and Ethereum, wallet accounts are created based on the public key used in public key cryptography. Virtual currency users manage their remaining virtual currency balances on a per-wallet account basis.

[0021] A "transaction" is cryptocurrency transaction data recorded on the blockchain. Generally, it is data that records a transfer from one wallet account to another. A transaction is issued when a wallet account sending cryptocurrency signs a transaction that lists its own wallet account and the destination wallet account with its own private key and sends it.

[0022] "Mining" is the process of compiling multiple issued transactions into a single block that can be recorded on the blockchain and recording it at the beginning of the blockchain (Reference: M. Omri, A conceptual framework for the regulation of cryptocurrencies, U. Chi. L. Rev. Dialogue, Vol. 82, pp. 53-68, 2015.). By recording the transaction on the blockchain, the transaction history is confirmed in an irreversible form. It takes several minutes from the issuance of a transaction to its confirmation.

[0023] Next, SAGA BC The configuration of the information communication system 1 of this embodiment based on the system 100 will be described. FIG. 1 is a system overview diagram of the information communication system of this embodiment. The information communication system 1 is a SAGA BCThe system configuration is based on system 100 and includes information communication devices 10 (10a, 10b) used by users to send and receive e-mails via the Internet 13, a mail server 11 (mail sending server 11a, mail receiving server 11b) that manages the sending and receiving of e-mails used by each user, and a blockchain 12 of virtual currency exchanged between each user of information communication devices 10a, 10b.

[0024] For example, when an email is sent from an email address set in one email account used by one user as a sender to an email address set in another email account used by another user as a recipient, i.e., when an email is sent from information communication device 10a to information communication device 10b as shown in FIG. 1, the email created by information communication device 10a is sent to information communication device 10b via email sending server 11a for the sender and email receiving server 11b for the recipient. This series of email transmissions is performed using a typical method, for example, via an SMTP server or a POP3 server. At the same time as sending the email, information communication device 10a generates a virtual currency remittance transaction and broadcasts it to the blockchain 12. The remittance transaction generated at this time indicates the transfer of a predetermined amount of virtual currency from the wallet of the sender, who is the user of information communication device 10a, to the wallet of the recipient, who is the user of information communication device 10b.

[0025] The information communication device 10b receives the email (provisionally received at this stage) and accesses the blockchain 12 to check the deposit status of the email, such as whether the virtual currency has been deposited into the recipient's wallet or whether the deposit amount is equal to or greater than a predetermined amount. Only when the deposit status is appropriate, such as when the deposit is confirmed or when a deposit of a predetermined amount or more is confirmed, is the email received as a legitimate email and displayed in the inbox or sorted as a legitimate email. If the deposit status is inappropriate, such as when the deposit is not confirmed or when the deposit is less than a predetermined amount, the email may be unconditionally discarded or moved to the trash, or it may be displayed in the inbox once and then displayed in a way that the recipient can recognize that the email does not contain any virtual currency (for example, by displaying an alert, highlighting, or displaying in a different color).

[0026] For ease of understanding, the above description is of one-way information communication in which an email is sent and virtual currency is transferred from information communication device 10a, on which one account (one email account and one wallet account) used by one user is set as the sender, to information communication device 10b, on which another account (another email account and another wallet account) used by another user is set as the receiver, and email is received and the deposit of virtual currency is confirmed on information communication device 10b used by the other user. However, both information communication device 10a used by one user and information communication device 10b used by the other user have the function of sending and receiving emails in both directions, as well as the function of transferring virtual currency and confirming the deposit, etc.

[0027] In the information and communication system 1 shown in Fig. 1, an email account for sending and receiving emails is linked to a wallet account for accessing the blockchain 12. In the information and communication system 1, a wallet account is assigned to each email account held by an email client. In other words, the email client links a virtual currency wallet account to the email address set in the email account.

[0028] MSC (Mail Send Coin) is created and used as the virtual currency implemented in the information and communication system 1. This MSC is not intended to have monetary value, but is a virtual currency that is added when sending email (transferred when sending email or refunded when receiving legitimate email). Note that existing virtual currencies such as Bitcoin and Ethereum may also be used as MSC.

[0029] The main functions of the information communication system 1 are implemented in a mailer installed in the information communication devices 10a and 10b. A typical mailer is software for sending and receiving e-mails, and manages sending and receiving from one or more e-mail addresses. In the information communication system 1, the functions required for the information communication system 1 are implemented as extended functions in the typical mailer. The main contents of the extended functions are specifically described below.

[0030] (1) Account management function It has the function of managing wallet accounts corresponding to users' email accounts. (2) Account registration function It has the function of associating the hash value of an email address with a wallet account and registering it on the blockchain. (3) Account verification function When sending an email, it has the function of checking the wallet account corresponding to the destination email address. (4) Incoming mail and deposit MSC support function It has the function of matching received emails with deposited MSCs, and the function of storing that data. (5) Spam filtering function Depending on the amount of MSC deposit for each received email, the email can be displayed, sorted into a spam folder, or deleted. (6) Money transfer function It has the function to send MSC from a Weret account corresponding to one's own email account, and the function to determine the amount to send (hereinafter referred to as the amount of MSC to be sent). (7) Mining function When there is a shortage of MSC to transfer when sending an email, MSC is replenished by mining MSC transactions issued by many users. SPAMers can also replenish MSC using this function, but this requires a large amount of computational cost.

[0031] Information and Communication System 1 is SAGA BC By using the system 100, it is possible to obtain the history of email transmissions, such as which email account sent which email, from which email account, based on the transaction history of MSC, such as which wallet account sent MSC to which wallet account. In other words, even in an open system environment where centralized management was previously impossible, such as email exchanges, SAGA BC It is possible to manage the sending and receiving of such emails by using the system 100. Furthermore, in this embodiment, it is possible to suppress spam emails by evaluating accounts based on the PageRank algorithm described below from the history data of email sending and receiving, and by identifying accounts that are spammers based on the evaluation.

[0032] The PageRank algorithm is used to rank web pages, for example, in search engine search results. This algorithm considers the number and quality of links to a page to roughly estimate the importance of a website. Initially, all pages are given a uniform rank score. Each page's rank score is then recalculated based on its link structure, and this process continues until the rank score shows little change. PageRank is calculated using matrix operations. Each page's final rank is determined by calculating the recurrence formula until it converges. The PageRank algorithm also introduces a damping factor to account for the probability of randomly selecting a page and following its links. This algorithm is important for effectively organizing information on the web and allowing users to access more important content. More accurate rankings can be achieved by calculating PageRank based not only on the number of links but also on the trustworthiness and quality of those links.

[0033] The account evaluation algorithm in this embodiment, which applies this PageRank algorithm, is called MARA (Mail Account Rank Algorithm). The PageRank algorithm calculates a score value representing the evaluation of a node using nodes that indicate web pages or their URLs and edges that indicate links between web pages, whereas MARA, shown in the following formula (1), uses accounts as nodes and generates a network graph in which edges connect MSC transactions between one sender's account and another receiver's account. The PageRank algorithm is applied to this network graph to calculate the score value of the node.

[0034]

number

[0035] In equation (1), PR(A) is a score indicating the evaluation of the target account, d is a coefficient representing the probability that a user of an information and communication system will randomly transfer the virtual currency, PR(T1) to PR(Tn) are score values ​​indicating the evaluation of other accounts T1 to Tn that are the senders of the virtual currency that transferred the virtual currency to the target account, and C(Tn) is the number of recipient accounts to which the other accounts T1 to Tn transferred the virtual currency.

[0036] Since spammers send large amounts of spam emails unilaterally to many accounts (with almost no replies), MARA inevitably gives spammers a low score and a low rating. By setting the cost required to send email for each account according to the rating, spammers incur high sending costs when sending emails to an unspecified number of people, and if the recipient determines that the email is spam, the MSC they sent to the recipient will not be refunded. As a result, spammers are unable to send spam emails. In contrast, the general SAGA BC The user's account in the system 100 is expected to be able to send and receive e-mails as usual, since the MSC amount of e-mails sent is more likely to be returned as is than for spammers.

[0037] SAGA BC System 100 uses a method of suppressing spam mail by requiring a predetermined amount of MSC (hereinafter referred to as the sending MSC amount) as a cost when sending e-mail.Therefore, by varying and setting the sending MSC amount required to legitimately receive e-mail according to the score value and rank of the sending account, based on the account evaluation obtained by MARA, spam mail can be suppressed in a shorter period of time.

[0038] In this embodiment, account information, which serves as nodes, and deposit and withdrawal information, which serves as edges, are extracted from the blockchain 12 to generate a network graph. Here, accounts are defined as nodes, and N nodes corresponding to all N accounts of users using the information and communication system 1 are created. Each node has a node ID (account ID) and information on the amount of MSC it holds. In addition, the node may have information on its type (general account / spamer) and rank. Furthermore, in the information and communication system 1, when an email is sent, MSC is transferred from a wallet account corresponding to the sender to a wallet account corresponding to the recipient. This MSC transfer information is used as an edge to connect to the above-mentioned nodes to create a directed graph. If the recipient determines that the received email is legitimate and not spam, the recipient refunds the amount of MSC received at the time of receipt to the sender. Therefore, two edges, one for the time of sending and one for the time of refund, are created for each email. If the recipient determines that the received email is spam, the MSC is not refunded, and only one edge is created for each email.

[0039] Figure 2 is an image of a network graph created from email transmission information, and Figure 3 is an image of a network graph created from nodes and edges based on MSC deposit and withdrawal information. As shown in Figures 2 and 3, there are cases where there is one edge or two edges for email transmission.

[0040] 4 is an image diagram of a network graph actually generated by MARA in the information communication system according to this embodiment. In the above formula (1), for one account to be evaluated (e.g., account B in FIG. 4), the other remittance source accounts that have sent MSC remittances are T1 to Tn (e.g., corresponding to accounts C, D, E, F, and Z1 to Z3 in FIG. 4). The score value PR(B) of one account is calculated based on the score values ​​of the other accounts (numbers shown as % in FIG. 4, corresponding to PR(C), PR(D), PR(E), PR(F), and PR(Z1) to PR(Z3)). Each score value of the other accounts that affect the score value PR(B) of the one account is calculated by dividing C(Tn), which is the number of remittance destination accounts to which Tn has sent money (e.g., corresponding to C(C), C(D), C(E), C(F), and C(Z1) to C(Z3) in the example of FIG. 4).

[0041] That is, if Tn is a spammer (Z1 to Z3 in Figure 4) and is sending money to one account B as one of a huge number of recipients, the impact of Tn on the score value of one account B will be minimal. On the other hand, if Tn is a regular user (C, D, E, F in Figure 4), the impact of Tn on the score value of one account B will be large, since Tn is sending money to one account B as one of a normal number of recipients.

[0042] If an account only sends e-mails unilaterally, like a spammer, the score value will gradually decrease, as shown by Z1 to Z5 in Figure 4, and the account will be given a low rating. This makes it possible to distinguish between spammers and normal users. MARA calculates and evaluates the score value of each node for the generated graph of nodes and edges in Figure 3 using the algorithm shown in formula (1).

[0043] The MARA processing unit can also calculate different scores using multiple different algorithms, in which case each user can freely decide which algorithm to use for the calculated score.

[0044] In the information and communication system 1, users with low-rated accounts are required to pay higher transmission costs when sending emails, thereby preventing spammers from sending spam emails. Therefore, in this embodiment, the MSC amount required for sending emails is set according to the score value calculated above. That is, in the example of FIG. 4, when an email is sent from account Z1 with a low rating, the email will not be received as legitimate unless a large MSC amount is set according to the score value (low) or score rank (low). On the other hand, when an email is sent from account B with a high rating, the email will be received as legitimate if a small MSC amount is set according to the score value (high) or score rank (high). In the case of a normal user who sends and receives normal emails, such as account B, the sending MSC amount is refunded as is, so even if a large MSC amount is required when sending emails, there is almost no impact. However, in the case of a spammer-like user, such as account Z1, the sending MSC amount is not refunded, so mining or the like is required to obtain the sending MSC amount, which ultimately makes it possible to eliminate spammers.

[0045] In this embodiment, the MARA processing is executed on the MARA platform. The score results and score ranking information are also managed on the MARA platform. The MARA platform may be incorporated as an add-on function of a mailer, for example, to enable individual calculations for each user, or may operate based on an autonomous program whose source code is published on the blockchain 12, or a dedicated device for MARA may be provided separately and the MARA platform may be implemented on that device. The evaluations (scores) calculated by MARA may be accessible from the accounts of all users of the information and communication system 1.

[0046] The following describes a configuration in which the MARA platform is incorporated as an add-on function of a mailer installed in the information communication device 10. FIG. 5 is a functional block diagram showing the configuration of an information communication device in an information communication system according to this embodiment. First, the processing when sending an email will be described. In FIG. 5, the information communication device 10 includes an input / output unit 21 that inputs and outputs information in response to operations by the sender of the email, an outgoing email creation unit 22 that creates an email to be sent in response to the input operation, an email sending unit 23 that sends the created outgoing email to the email sending server 11a, a correspondence information storage unit 24 that stores the email addresses of the sender and recipient (the email address of the sender and the email address of the recipient) in association with wallet accounts, a private key storage unit 25 that stores a private key required as a signature when accessing the blockchain 12, and a remittance control unit 27 that generates a remittance transaction for sending an MSC and signs the generated remittance transaction using the private key information stored in the private key storage unit 25 and broadcasts it to the blockchain 12. These components function in the processing when sending an email.

[0047] The remittance control unit 27 performs a remittance process of the MSC from the sender's wallet to the receiver's wallet. FIG. 6 is a diagram showing an example of information stored in the correspondence information storage unit 24. The correspondence information storage unit 24 stores email addresses, which are identification information for identifying each sender and receiver of an email, and wallet accounts, which are identification information required to access the blockchain 12, in one-to-one correspondence. The remittance control unit 27 extracts the corresponding wallet account from its own email address, which is the sender of the outgoing email created by the outgoing email creation unit 22. It also extracts the corresponding wallet account from the destination email address, which is the recipient of the outgoing email. Using these wallet accounts, the remitter's wallet account and the remitter's wallet account are identified, and a remittance transaction is created by setting the amount of the sending MSC, which is the amount to be remitted.

[0048] The sending MSC amount set here is the remittance amount required for the email to be sent to be received as a legitimate email, and is set based on the rank information stored in the rank memory unit 52 in the MARA platform 50. The MARA calculation unit 51 and rank memory unit 52 in the MARA platform 50 will be described in detail later, but for example, the remittance control unit 27 calculates the sending MSC amount using a function f (rank order) that takes as an argument its own rank order stored in the rank memory unit 52. Note that, as a general rule, the sending MSC amount is the amount calculated by the function f, but it may also be variable by the sender as needed.

[0049] Returning to Figure 6, when the remittance control unit 27 creates a remittance transaction for the above-mentioned transmission MSC amount, it can broadcast the created remittance transaction to the blockchain 12 by signing it with the private key information stored in the private key storage unit 25, and write the remittance information (remittance history) to the blockchain 12. Since it is extremely difficult to tamper with the blockchain 12, the remittance information written here is highly reliable and can function as the value of the sent email.

[0050] Next, the processing when receiving an email will be described. In Fig. 5, the information communication device 10 includes a mail receiving unit 28 that receives an email addressed to the recipient from the mail receiving server 11b, a reception control unit 29 that reads from the correspondence information storage unit 24 the wallet account corresponding to the sender's email address from the email received by the mail receiving unit 28 and queries the blockchain 12 to confirm whether or not an MSC remittance has been made by the sender and / or the remittance amount, and a received email processing unit 30 that displays the received email as a legitimate email if an MSC remittance has been made by the sender or if the remittance amount is equal to or exceeds a preset threshold (hereinafter referred to as the received MSC threshold), and otherwise performs processing such as discarding the received email as an invalid email. These components function in the processing when receiving an email.

[0051] Each processing unit will be described in more detail. FIG. 7 is a diagram showing the processing of the reception control unit 29. As shown in FIG. 7, the reception control unit 29 extracts the corresponding wallet account from the email address of the sender, who is the sender of the email received by the email reception unit 28. At the same time, it extracts the wallet account from the recipient's own email address, which is the destination, who is the recipient. From these extracted wallet accounts, an inquiry is made to the blockchain 12 to confirm the deposit status of the MSC from the sender's wallet account to the recipient's own wallet account. Information on the confirmed deposit status is passed to the received email processing unit 30 together with information on the received email.

[0052] The received email processing unit 30, which receives the email information and the information regarding the deposit status, performs predefined processing on the received email depending on the deposit status (whether or not a deposit has been made or whether or not a deposit of a predetermined amount has been made) (for example, displaying it in the inbox normally, displaying it in the inbox together with information regarding whether or not a deposit has been made or the amount of the deposit, discarding it in the trash, discarding it completely, processing it as spam, etc.).

[0053] The processing of the received mail processing unit 30 may be specified according to the amount of the deposited MSC. For example, received e-mails may be sorted into different folders according to the amount of the deposit, or if a predetermined amount or more has been deposited, the e-mail may be highlighted, and if the amount is less than the predetermined amount, the e-mail may be displayed normally. In this way, if there is an urgent matter, a larger amount of MSC may be transferred to encourage the user to check e-mails as a priority.

[0054] Furthermore, information from the rank storage unit 52 of the MARA platform 50 may be read, and the processing of the received mail processing unit 30 may be specified according to the evaluation of the sender's account. For example, emails may be sorted into folders according to the score value or score ranking of the account, or emails may be highlighted when the score value is equal to or greater than a predetermined value or when the score ranking is higher than a predetermined rank, and displayed normally when the score value is less than the predetermined value or when the score ranking is lower than the predetermined rank.

[0055] As described above, the reception control unit 29 determines whether the amount of MSC sent from the sender is equal to or greater than the reception MSC threshold and passes the determination result to the received email processing unit 30. This reception MSC threshold is calculated, for example, by a function f (rank order) that takes as an argument the rank order of the sender's account stored in the rank storage unit 52. The reception MSC threshold is generally determined using a threshold calculated by the function f, but may be variable by the receiver as needed. As described above, if the transmission MSC amount and the reception MSC threshold are calculated using the same function f, the transmission MSC amount and the reception MSC threshold will have the same value. Therefore, if the transmission MSC amount is deposited from the sender's wallet account to the receiver's wallet account at the time of sending the email, the email will be received as a legitimate email.

[0056] Next, the processing for refunding when an email is received will be described. In Fig. 5, the information communication device 10 is equipped with a refund control unit 31 that generates a remittance transaction for sending the MSC from the wallet account of the destination (receiver) to the wallet account of the sender (sender) in order to refund the MSC deposited when the email was received, depending on the processing content of the received email executed by the received email processing unit 30 and the operation content performed by the recipient at the input / output unit 21, and that signs the generated remittance transaction using private key information stored in the private key storage unit 25 and broadcasts it to the blockchain 12.

[0057] The refund control unit 31 performs a process to refund the MSC deposited when the email was received, depending on the processing performed by the received email processing unit 30 on the received email and the operation performed by the recipient on the input / output unit 21. Specifically, for example, if the received email is determined to be SPAM email (illegal email) by the standard functions of the mail server or mailer and discarded by the received email processing unit 30, no refund process will be performed. Furthermore, if the email is received as legitimate and displayed in the inbox, but the recipient does not operate the input / output unit 21 and does not refer to the contents, or if the recipient refers to the contents but ultimately discards them, no MSC will be refunded. If the recipient ultimately refers to and saves the contents of the received email, or creates and sends a reply email to the received email, all of the MSC deposited at the time of receipt will be refunded. In addition, the refund control unit 31 determines not to perform a refund process for emails sent from accounts whose score value calculated by the MARA platform 50 is below a predetermined value or whose score ranking is below a predetermined rank.

[0058] The refund process by the refund control unit 31 is similar to the remittance process performed when sending an email, and the refund control unit 31 accesses the correspondence information storage unit 24 and extracts the wallet account from the email address of the sender who is the sender of the received email. A remittance transaction (hereinafter referred to as a refund transaction) for the refund amount determined above is generated from the recipient's own wallet account, which is the destination, to the sender's wallet account, and signed with the private key information stored in the private key storage unit 25. The generated refund transaction is broadcast to the blockchain 12 to execute the refund process.

[0059] When a refund process occurs, the sender may be notified of this. Furthermore, if certain conditions are met, the refund amount may be set to any amount less than the deposited amount, and if other conditions are met, the refund amount may be set to any amount equal to or greater than the deposited amount. For example, if it is determined that the email received this time is not spam but that it will not be received in the future (does not want to receive it or does not need to receive it), the refund amount may be set to a portion of the deposited amount (e.g., half the amount). Furthermore, if it is determined that the received email is more useful than expected, the refund amount may be set to a value higher than the deposited amount (e.g., a surcharge according to the usefulness).

[0060] Next, the evaluation process executed at any timing will be described. In Fig. 5, the information communication device 10 is equipped with a MARA platform 50 that evaluates and manages accounts based on MSC deposit and withdrawal information (transactions) managed on the blockchain 12. The MARA platform 50 is equipped with a MARA calculation unit 51 that creates a network graph and performs calculations using MARA as described in Figs. 2 to 4, and a rank storage unit 52 that stores the results of calculations performed by the MARA calculation unit 51.

[0061] 8 and 9 are diagrams showing the processing of the MARA calculation unit 51, where FIG. 8 is a diagram showing the processing of creating a network graph and executing MARA, and FIG. 9 is a diagram showing the processing of creating a network graph. In FIG. 8, the MARA calculation unit 51 acquires transaction information managed on the blockchain 12 for each user's wallet account. As shown in FIG. 8(A), each transaction 1 to N consecutively lists information on the MSC's sender wallet account and recipient wallet account. The transactions acquired here may be all transactions on the blockchain 12, transactions falling within a period arbitrarily set by the user, or transactions of an account arbitrarily set by the user and accounts related to that account. In other words, the objects of calculation by the MARA calculation unit 51 can be arbitrarily set.

[0062] When the MARA calculation unit 51 acquires information on any transaction such as that shown in FIG. 8(A), it then extracts the wallet account of the MSC sender and the wallet account of the recipient as nodes from the information on each transaction, as shown in FIG. 9(A). The extracted nodes are shown as circles in FIG. 9(A). The MARA calculation unit 51 also extracts the flow of MSC remittance as edges. The extracted edges are shown as arrows in FIG. 9(A). This makes it possible to graphically recognize the relationship between which wallet account the MSC moved to and from. By performing this process on all acquired transactions, a network graph showing a network structure such as that shown in FIG. 9(B) is generated using nodes and edges.

[0063] Returning to Fig. 8, when a network graph such as that shown in Fig. 9(B) is generated (corresponding to Fig. 8(B)), the MARA calculation unit 51 executes the MARA shown in equation (1) (Fig. 8(C)). By the MARA calculation of equation (1), a score value for each node is calculated, and a score ranking is created in which accounts with higher score values ​​are ranked higher, as shown in Fig. 8(D). The generated network graph, as well as information on the score values ​​and score ranking, are stored in the rank storage unit 52.

[0064] The MARA calculation processing by the MARA calculation unit 51 may be performed at any timing in accordance with the user's instructions, at a preset timing, or each time an e-mail is sent and / or an e-mail is received.

[0065] Next, the operation of the information communication device according to this embodiment will be described. FIG. 10 is a flowchart showing the processing performed when an email is sent (when an MSC remittance is performed) in the information communication device according to this embodiment. In FIG. 10, first, the outgoing email creation unit 22 creates an outgoing email in response to an operation of the input / output unit 21 performed by the sender (S1). The email sending unit 23 sends the created outgoing email to the email sending server 11a (S2). At the same time that the outgoing email is handed over to the email sending unit 23 in S2, the remittance control unit 27 receives the email address of the destination, which is the recipient of the outgoing email (S3). The remittance control unit 27 accesses the correspondence information storage unit 24 and extracts wallet accounts corresponding to the email addresses of the destination, which is the recipient, and the sender's own email address (S4). The remittance control unit 27 queries the MARA platform 50 and, based on its own rank, calculates the amount of outgoing MSC that can be received by the recipient as a legitimate email (S5), and compares the amount of outgoing MSC with the amount of MSC held in the sender's wallet account (S6). If the amount of MSC held is less than the amount of MSC to be sent, the process ends without sending the email. If the amount of MSC held in S6 is equal to or greater than the amount of MSC to be sent, a remittance transaction is generated to send the MSC from the sender's wallet account to the recipient's wallet account (S7). The private key information is read from the private key storage unit 25, and the generated remittance transaction is signed (S8). The generated remittance transaction is then broadcast to the blockchain 12 (S9), completing the email sending process.

[0066] As described above, in S6, if the amount of MSCs held is less than the amount of MSCs to be sent, the e-mail may not be sent, or the amount of MSCs to be sent may be changed to fall within the range of the amount of MSCs held. In this case, depending on the response of the recipient, the sent e-mail may be received as a legitimate e-mail, or may be treated as spam and thus be treated as an invalid e-mail.

[0067] FIG. 11 is a flowchart showing the process of receiving an email in the information communication device according to this embodiment. In FIG. 11, first, the email receiving unit 28 receives an email from the email receiving server 11b (S1). The reception control unit 29 receives the email address of the sender of the received email (S2). The reception control unit 29 accesses the correspondence information storage unit 24 and extracts wallet accounts corresponding to the respective email addresses from the email address of the sender (the sender) and the user's own email address (the recipient) (S3). The reception control unit 29 queries the blockchain 12 regarding the status of MSC deposits from the sender's wallet account (the sender) to the user's own wallet account (the recipient) (S4). The reception control unit 29 queries the MARA platform 50 and determines whether the deposited MSC is equal to or greater than the received MSC threshold calculated based on the rank of the sender's account (S5), and passes the determination result to the received email processing unit 30. If the received email processing unit 30 receives a determination result indicating that the amount of the deposited MSC is equal to or greater than the received MSC threshold, the received email processing unit 30 executes processing to display the received email as a legitimate email (S6). If the determination result is that the amount of the deposited MSC is less than the received MSC threshold, the received email is treated as an invalid email and processing is executed to prevent the email from being displayed (S7), and the email reception processing is completed.

[0068] 12 is a flowchart showing a refund process in the information communication device according to this embodiment. In FIG. 12, first, the refund control unit 31 receives the processing mode of the received email processing unit 30 in the process of receiving an email, the processing mode of the input / output unit 21, and / or evaluation information such as the score value and score ranking of the sender's account managed by the MARA platform 50 (S1). The refund control unit 31 determines whether the received processing mode corresponds to the processing mode when a legitimate email is received, or whether the evaluation information is equal to or higher than a predetermined evaluation (S2). If the refund control unit 31 determines in S2 that the received processing mode corresponds to the processing mode when a legitimate email is received and that the evaluation satisfies the predetermined evaluation, it sets the refund amount to an amount equal to the MSC deposited when the email was received (S3). On the other hand, if the refund control unit 31 determines in S2 that the received processing mode does not correspond to the processing mode when a legitimate email is received, or if it determines that the evaluation does not satisfy the predetermined evaluation, it sets the refund amount to 0 (S4).

[0069] The refund control unit 31 accesses the correspondence information storage unit 24 and extracts the wallet accounts corresponding to the respective email addresses from the email address of the sender (the sender) and the user's own email address as the destination (the recipient) (S5). It generates a refund transaction for sending the MSC from the user's own wallet account as the destination (the recipient) of the received email to the wallet account of the sender (the sender) (S6). It reads private key information from the private key storage unit 25 and signs the generated refund transaction (S7). The generated refund transaction is then broadcast to the blockchain 12 (S8), completing the refund process.

[0070] Fig. 13 is a flowchart showing the evaluation process in the information communication device according to this embodiment. In Fig. 13, the MARA calculation unit 51 of the MARA platform 50 accesses the blockchain 12 to acquire any transaction (S1). A network graph is generated with the accounts in the acquired transaction as nodes and remittance information as edges (S2). The generated network graph is evaluated using MARA in formula (1) (S3). A score ranking is calculated based on the score value of the evaluation result (S4), and the calculation result is stored in the rank storage unit 52 (S5), terminating the process.

[0071] As mentioned above, the MARA platform 50 may be implemented on the blockchain 12, or may be implemented on a dedicated device for the MARA platform 50 accessible from the information communication device 10, or may be implemented on a web server, mail server, etc. In this case, each processing unit of the remittance control unit 27, the reception control unit 29, and the refund control unit 31 will access the device on which the MARA platform 50 is implemented and refer to the rank information.

[0072] In addition, although the above description has been given with one email account associated with one wallet account, one wallet account may be associated with multiple email accounts, or multiple wallet accounts may be associated with one email account.

[0073] In this way, in the information and communication system of this embodiment, when sending an email, a remittance transaction is generated to transfer a specified MSC to the destination account in conjunction with the sending of the email, and this is broadcast to the blockchain 12. When receiving an email, if the email is determined to be a legitimate email, a refund transaction is generated to refund the MSC deposited in conjunction with the receipt of the email directly to the sender's account, and this is broadcast to the blockchain 12. The information and communication system 1 analyzes the deposit and withdrawal status of the MSC stored in the blockchain 12 for each target account of a user of the information and communication system 1 to calculate a score value, and evaluates the target account based on this score value.Therefore, the accounts of system users are evaluated based on the deposit and withdrawal status of the MSC, and as a result, it is possible to identify user accounts that are spammers and suppress SPAM emails.

[0074] In addition, when an account is evaluated on the MARA platform 50, the MARA calculation unit 51 calculates the score value and score ranking based on the formula (1), and therefore applies the page rank algorithm for ranking web pages in search results of a search engine to the SAGA BC The system 100 can properly evaluate the accounts of users of the system 100, and based on the evaluation results, can appropriately vary the cost required to send e-mail, thereby eliminating spammers and suppressing SAPM e-mails.

[0075] Furthermore, the sending MSC amount required for an email to be sent to be received as legitimate, and the receiving MSC threshold, which is the standard for receiving an email as legitimate, are calculated based on the score value of the sender's (sender's) account, so the appropriate sending and receiving amounts for a normal user can be calculated individually based on the account evaluation. [Example]

[0076] A simulation experiment was conducted using the information and communication system 1 according to the present invention. First, the accuracy of spammer detection when using the information and communication system according to the present invention was verified. In this example, the simulation experiment was conducted using the Python language. FIG. 14 is a diagram showing parameters used in the simulation in the example. In the simulation, multiple patterns of refund probability when receiving email were prepared for each normal account and spammer account, as shown in FIG. 14(A). In addition, for each normal account and spammer account, the initial MSC amount and the number of emails sent were set as shown in FIG. 14(B). Furthermore, the cost of sending email (sent MSC amount) was set as shown in FIG. 14(C) when using the MARA of the present invention and when not using the conventional MARA. MARA's range of 1 to 100 means that it fluctuates depending on the score ranking.

[0077] FIG. 15 is an NS chart showing the main routine of a simulation for verifying the accuracy of spammer detection in this embodiment. (1) Initial settings SAGA in virtual space BC Create accounts for 1,000 people who will use System 100. The initial MSC value possessed by all accounts is set to 100,000. Of the 1,000 people, 10 are spammers and 990 are general accounts. (2) Sending and Remittance Loop A regular account will send an email to 15 randomly selected regular accounts, excluding themselves and spammers, and simultaneously transfer 1 MSC. (3) Refund The email receiver refunds the MSC to the email sender based on the arbitrary refund probability shown in FIG. 14(A). (4) General Account Loop Repeat steps (2) and (3) until 990 general accounts have sent emails to 15 people. Note that general accounts will not engage in mining. (5) Sending and Remittance Loop At the same time as sending the email, the spammer transfers 1 MSC to the general accounts of 30 randomly selected people. (6) Refunds The general account that receives the email will refund the MSC sent by the spammer based on the arbitrary refund probability shown in Figure 14(A). (7) SPAMer Loop Repeat this process until 10 spammers have sent emails to 30 randomly selected public accounts. Note that the spammers are not mining. (8) Rank calculation Calculate the rank of all accounts based on the data obtained in steps (1) to (7).

[0078] The above simulation experiment was conducted with 1,000 accounts, using a total of 64 patterns of combinations of the refund probability for normal accounts and the refund probability for spammers, as shown in Figure 14. According to a survey on actual business emails, the average number of business emails sent per day is 15.24. Therefore, the number of emails sent per day by normal accounts was set to 15. Furthermore, since the number of emails sent by spammers is unknown, the number of emails sent per day was set to 30. The number of accounts was set to 1,000, and 10 accounts, or 1% of those, were considered spammers.

[0079] First, all accounts send and receive email for one day. From the results for that day, a network graph is generated, with accounts as nodes and MSC transfers and refunds as edges. Using Python's networkX, MARA calculates the rank scores for all accounts on that graph. Based on the calculated scores, the accounts are ranked in descending order of rank score, and the rank ranking information is assigned to the nodes. The assigned rank ranking information then changes the amount of MSC that must be paid when sending email. We then verify whether spammers are ranked lower.

[0080] 16 shows the results of a simulation performed to verify the accuracy of spammer detection in this embodiment. As shown in FIG. 16, the simulation results show that spammers are ranked low in 60% of all 64 patterns. Furthermore, considering that the probability of a spammer receiving a refund of 80% or more is extremely low in a real environment, this embodiment shows that 92% of spammers are ranked low. Furthermore, when the probability of a spammer receiving a refund is 80% or more, the spammer sends 30 emails and the accompanying MSCs and receives a refund, resulting in a higher ranking than a general account.

[0081] From the above, in the MARA system, the more edges connected to a node, that is, the higher the probability of refunds, the higher the rank. Spammers do not receive emails from general accounts. However, if the probability of refunds to a spammer is high, the number of edges connected to the spammer increases, exceeding the number of edges connecting general accounts, and the average rank of the spammer may only occasionally be higher than 100th place. However, since the probability of refunds to general accounts is usually 60% or higher and the probability of refunds to spammers is 60% or lower, the information and communication system 1 according to the present invention can be used to identify spammers with high accuracy.

[0082] Next, we verified to what extent the information communication system according to the present invention can suppress spam mail from spammers.

[0083] FIG. 17 is an NS chart showing the main routine of a simulation for verifying the suppression of spam mail in this embodiment. (1) Rank setting Create accounts for 1,000 people who use MARA in the virtual space. The initial MSC value possessed by all accounts is set to 100,000. Of the 1,000 people, 10 are spammers and 990 are general accounts. Set the amount of MSC to be sent based on the account rank information obtained in advance. (2) Sending and Remittance Loop Two cases will be conducted simultaneously: one with MARA and one without. A regular account will send emails to 15 randomly selected accounts, excluding the account itself and spammers, and will also transfer MSC. For those using MARA, the amount of MSC sent will vary depending on the rank. If the user does not have the MSC required for the transfer, the email will not be sent. (3) Refund For emails sent by 990 general accounts, MSC refunds are made based on the arbitrary refund probabilities shown in Figure 14(A). (4) General Account Loop Repeat steps (2) and (3) until emails are sent to 15 of the 990 general accounts. Note that general accounts will not be used for mining. (5) Sending and Remittance Loop Two cases are performed simultaneously: one using MARA and one not. The spammer sends an email to a randomly selected general account and simultaneously transfers MSC. For those using MARA, the amount of MSC required to send varies depending on the rank. If the spammer does not have the MSC required to transfer the money, the email will not be sent. (6) Refunds The general account will refund the virtual currency of the MSC sent by the spammer based on the refund probability shown in Figure 14(A). (7) SPAMer Loop The spammer will repeat this process until they have sent 30 emails to each randomly selected general account. Note that the spammer will not mine. (8) 10-day loop (2) to (7) count as one day, and repeat from day 1 to day 10. (9) 10-time loop Repeat (8) 10 times. (10) Output the average of 10 times The average of the results of 10 runs of data from the 10th day of one pattern will be output to a CSV file. (11) 64 pattern loops

[0084] We repeated 64 patterns of combinations of the general account and spammer refund probability shown in Figure 14(A). Higher-ranked accounts require less MSC to send email, while lower-ranked accounts require more. Here, we assumed that the amount of MSC sent equals rank. Because the rank score output by MARA depends on the direction and number of edges, the account's rank score changes depending on the percentage of MSC refunded. Therefore, we set the MSC refund probability from general accounts to other general accounts and from general accounts to spammers to 0, 1, 20, 40, 60, 80, 99, and 100%, respectively. We also assumed that general accounts send 15 emails per day and spammers send 30 emails per day for 10 days. We performed all 64 patterns 10 times for 10 days, and output the average results of the 10 runs to a CSV file. We also conducted a similar experiment without MARA as a comparison to verify the effectiveness of MARA.

[0085] As simulation results using MARA, Figure 18(A) shows the average amount of virtual currency held by spammers, and Figure 18(B) shows the average number of emails sent by spammers. Figure 18(A) confirms that the average amount of virtual currency held by spammers drops sharply when the probability of refunding money to spammers is 99% to 80%, and that when the probability is 60% or less, the amount of virtual currency held falls below 100. We also found that when the probability of refunding money to general accounts is 0-1%, and the probability of refunding money to spammers is 80%, the average amount of virtual currency held by spammers is approximately three times the amount held when the probability of refunding money to other general accounts is high. This is thought to be because the number of edges to spammers exceeds the number of edges to other general accounts, causing spammers to be ranked higher.

[0086] Figure 18(B) also confirms that the average number of emails sent by a spammer also drops sharply from 99% to 80%. These results show that when using MARA, if the probability of refunding a spammer's funds is 80% or less, the amount of virtual currency held by the spammer will decrease, and if it is 60% or less, the amount of virtual currency held by the spammer will fall below 100, making it impossible to pay the sending MSC amount required for sending and making it almost impossible to send spam emails. It also becomes clear that the probability of refunds between regular accounts does not have a significant impact on the number of emails sent by a spammer.

[0087] Simulation results without MARA are shown in Figure 19(A) and Figure 19(B), respectively, showing the average amount of virtual currency held by spammers and the average number of emails sent by spammers. Figure 19(A) shows that spammers were unable to send emails regardless of the spammer refund probability. Figure 19(B) shows that spammers sent an average of 30 emails at all refund probabilities. These results demonstrate that without MARA, even a small spammer refund probability, such as 0% to 1%, cannot reduce spam emails in a short period of time, and that suppressing spam requires a long period of time. Furthermore, the refund probability between regular accounts has almost no effect on the number of emails sent by spammers. Comparing the results with and without MARA, we found that using MARA reduces spammers' average amount of virtual currency held and significantly reduces the average number of emails sent.

[0088] Figure 20(A) shows the average number of emails sent by general accounts when MARA is used, and Figure 20(B) shows the average number of emails sent by general accounts when MARA is not used. Figure 20(A) shows that when MARA is used, the number of emails sent increases as the probability of refunds to general accounts increases. Figure 20(B) shows that the number of emails sent by general accounts does not decrease when MARA is not used.

[0089] Simulation results confirmed that by using MARA, it is possible to set an appropriate amount of MSC to be sent to spammers, and that spam mail can be significantly reduced when the probability of a refund to the spammer is 60% or less. The reason for this is thought to be largely related to the amount of MSC to be sent according to rank. Because MARA forces spammers to pay large amounts of MSC to be sent, it is thought that even if there is a certain probability of a refund, the amount of virtual currency held by the spammer decreases more. By using MARA, it is possible to reduce spam in a short period of time. [Explanation of symbols]

[0090] 1. Information and Communication Systems 10(10a, 10b) Information and communication equipment 11 Mail Server 11a Mail sending server 11b Mail receiving server 12 Blockchain 13. Internet 21 Input / output section 22 Sending email creation section 23 Email sending section 24 Correspondence information storage unit 25 Private key storage 26 Remittance amount confirmation section 27 Remittance Control Unit 28 Mail Receiving Section 29 Reception control section 30 Incoming mail processing section 31 Refund Control Unit 50 MARA Platform 51 MARA Processing Department 52 Rank memory section

Claims

1. An information and communication system that, when sending an email, generates a remittance transaction for sending a predetermined virtual currency to a destination account in association with the sending of the email, broadcasts the transaction to a blockchain, and, when receiving the email, if the email is determined to be a legitimate email, generates a refund transaction for refunding the virtual currency deposited in association with the receiving of the email to the sender account as is, and broadcasts the refund transaction to the blockchain; An information and communication system characterized by comprising an evaluation means for analyzing the deposit and withdrawal status of the virtual currency stored in the blockchain for each target account of a user of the information and communication system, calculating a score value, and evaluating the target account based on the score value.

2. 2. The information communication system according to claim 1, An information and communication system characterized in that, when the evaluation means evaluates the target account, it calculates the score value based on the number of remittance accounts from which the virtual currency has been transferred to the target account from accounts other than the target account.

3. 3. The information communication system according to claim 2, An information and communication system characterized in that when the evaluation means evaluates the target account, it calculates the score value based on the number of recipient accounts to which the other account has transferred the virtual currency.

4. 3. The information communication system according to claim 1, An information communication system characterized in that when the evaluation means evaluates the target account, it evaluates based on the score values ​​of accounts other than the target account.

5. 5. The information communication system according to claim 4, An information and communication system characterized in that the evaluation means, when evaluating the target account, has a function calculation means that uses the score value of the other account as an argument and calculates the score value of the target account as a return value.

6. 5. The information communication system according to claim 4, When the evaluation means evaluates the target account, In formula (1), PR(A) is a score value indicating the evaluation of the target account, d is a coefficient representing the probability that a user of an information and communication system will randomly remit the virtual currency, PR(T1) to PR(Tn) are score values ​​indicating the evaluation of other accounts T1 to Tn that are remitters that remitted the virtual currency to the target account, and C(Tn) is the number of remittance destination accounts to which other accounts T1 to Tn remitted the virtual currency. An information communication system characterized by performing calculations based on the above formula (1).

7. 3. The information communication system according to claim 1, An information and communication system characterized by comprising a remittance control means that, when sending the email, calculates the amount of virtual currency to be remitted that is required for the email to be received as a legitimate email, based on the score value of the account of the sender of the email.

8. 3. The information communication system according to claim 1, An information and communication system characterized by having a reception control means that, when the email is received, calculates the amount of virtual currency deposited, which serves as the standard for receiving the email as a legitimate email, based on the score value of the account of the sender of the email.

9. an email sending means for sending email from one account to another; remittance control means for generating a remittance transaction for remitting the virtual currency from the one account to the other account when the email sending means sends the email and broadcasting the transaction to a blockchain; an email receiving means for receiving emails sent from another account to one account; a reception control means for, when the email receiving means receives the email, accessing the blockchain to confirm the deposit status of the virtual currency from the other account to the one account, and receiving the email as a legitimate email according to the confirmed deposit status; a refund control means for, when the reception control means receives the legitimate email, generating a remittance transaction for remitting the virtual currency in an amount equal to the amount of the remittance transaction from the one account to the other account in accordance with the virtual currency remittance transaction generated when the email was sent, and broadcasting the generated transaction to the blockchain; An information communication device characterized by comprising an evaluation means for analyzing the deposit and withdrawal status of the virtual currency stored in the blockchain for each user account, calculating a score value, and evaluating the account based on the score value.

10. An email sending means for sending email from one account to another; a remittance control means for generating a remittance transaction for remitting the virtual currency from the one account to the other account when the email is sent by the email sending means, and broadcasting the transaction to a blockchain; An email receiving means for receiving emails sent to one account from another account; a reception control means for, when the email receiving means receives the email, accessing the blockchain to confirm the deposit status of the virtual currency from the other account to the one account, and receiving the email as a legitimate email according to the confirmed deposit status; a refund control means that, when the reception control means receives the legitimate email, generates a remittance transaction for remitting the virtual currency associated with the email from the one account to the other account, and broadcasts the transaction to the blockchain; An information and communications program that causes a computer to function as an evaluation means that analyzes the deposit and withdrawal status of the virtual currency stored in the blockchain for each email account, calculates a score value, and evaluates the account based on the score value.

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