Information and communication system and information and communication device

Abstract

To provide an information and communications system, device, and program that identifies a user's account as a spammer and suppresses SPAM mail by evaluating the user's account from the deposit and withdrawal status of virtual currency associated with sending and receiving e-mail. [Solution] When sending an e-mail, a remittance transaction is generated to transfer a specified virtual currency to a destination account and broadcast it to the blockchain 12. When receiving an e-mail, if the e-mail is determined to be legitimate, a refund transaction is generated to refund the deposited virtual currency directly to the sending account and broadcast it to the blockchain 12. The information and communications system is equipped with a MARA platform 50 that analyzes the deposit and withdrawal status of the virtual currency stored in the blockchain 12 for each target account of a user of the information and communications system and evaluates the target account based on a score value calculated.

Description

[Technical field]

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

[0002] Emails received from unwanted recipients (hereafter referred to as SPAM emails) and the mail servers / mail accounts that send these SPAM emails (hereafter referred to as SPAMers) are a nuisance to most email users. According to a survey on SPAM emails conducted by Symantec in March 2009 ("The State of Spam A Monthly Report - March 2009"), it was found that approximately 86% of emails distributed worldwide are SPAM emails. In order to prevent spam mail from spammers, there are known methods to restrict mail by registering mail sending servers with specific IP addresses on a blacklist (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 / " (accessed: 2023-12-25).), and methods to restrict receiving mail by registering specific mail sending accounts (email addresses) on a blacklist, and Yahoo! Mail, for example, has its own spam filtering ("Yahoo!'s spam countermeasures", YAHOO! JAPAN Mail. https: / / mail.yahoo.co.jp / antispam / (accessed: 2023-12-25).).

[0003] However, these methods have a risk of misjudging, making it difficult to prevent spam mail. The reason for this is a problem with the algorithm that distinguishes the above-mentioned mail sending servers and mail accounts as spammers. Generally, mail sending servers and mail accounts that have sent a large amount of e-mails that are judged to be spam mail are judged to be spammers, but because they are only judged to be spammers after sending a large amount of spam mail, it is not possible to prevent spam mail in advance. In other words, there is a need for an algorithm that can distinguish spammers before sending a large amount of spam mail, or when they have sent a certain number of e-mails or less.

[0004] In addition, taking the above background into consideration, Patent Document 1 and Non-Patent Document 1 have been disclosed as technologies related to measures against SPAM mail. The technologies disclosed in Patent Document 1 and Non-Patent Document 1 include a mail 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 mail sending unit sends 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 and blockchain accounts are associated, 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 makes it possible to prevent 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] In addition, in the conventional method, after a spam mail is generated, incoming mail from the sending server is rejected, so by changing the sending server, it is possible to send further spam mail. In Patent Document 1 and Non-Patent Document 1, unless virtual currency is obtained by some means, it is not possible to send spam mail even if the sending server is changed. Furthermore, from the transaction history of virtual currency, which is the transaction history of which blockchain account remitted money to which blockchain account, it is possible to obtain the transmission and reception history, which is the history of which email account sent 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 mail, which can be roughly categorized into three types. The first is a method that judges by inspecting the contents of the mail, the second is a method that judges by the communication session, and the third is forcing costs on the SMTP connection. Thus, although there has been a lot of progress in spam mail countermeasures, conventional 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 mail by evaluating the user's account based on the deposit and withdrawal status of virtual currency associated with the sending and receiving of e-mail. [Means for solving the problem]

[0011] The information and communications system of the present invention generates, when sending an email, a remittance transaction for transferring a specified virtual currency to a destination account in conjunction with the sending of the email, and broadcasts this to a blockchain; 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 conjunction with the receipt of the email to the sender's account as is, and broadcasts this to the blockchain; and is equipped with 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 communications system, calculating a score value, and evaluating 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 a destination 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 deposited in conjunction with the receipt of the email to the sender's account as is, and this transaction 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 the score value, thereby evaluating the accounts of system users from the deposit and withdrawal status of the virtual currency, and as a result, it is possible to identify accounts of users that are spammers and suppress SPAM emails. [Brief description of the drawings]

[0013] [Figure 1] 1 is a system outline diagram of an information communication system according to a first embodiment of the present invention. [Diagram 2] FIG. 13 is an image diagram of a network graph created from email transmission information. [Diagram 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 actually generated in the information communication system according to the first embodiment of the present invention. [Diagram 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 corresponding information storage unit appearing in FIG. 5; FIG. [Figure 7] FIG. 6 is a diagram illustrating the process of a reception control unit in FIG. 5. [Figure 8]FIG. 6 is a diagram showing 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 showing 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] 4 is a flowchart showing a process performed when an e-mail 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] 4 is a flowchart showing an evaluation process in the information communication device according to the first embodiment of the present invention. [Figure 14] FIG. 11 is a diagram showing parameters used in a simulation in an example. [Figure 15] 1 is a NS chart showing a main routine of a simulation for verifying the accuracy of spammer determination in an embodiment. [Figure 16] FIG. 13 is a diagram showing the results of a simulation for verifying the accuracy of spammer determination in the embodiment. [Figure 17] 1 is an NS chart showing a main routine of a simulation for verifying suppression of SPAM mail in an embodiment. [Figure 18] FIG. 11 is a first diagram showing the results of a simulation for verifying the suppression of SPAM mail in the embodiment. [Figure 19] FIG. 2 is a second diagram showing the results of a simulation for verifying the suppression of SPAM mail in the embodiment. [Figure 20] FIG. 3 is a third diagram showing the results of a simulation for verifying the suppression of SPAM mail in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (First embodiment of the present invention) An information and communication system according to the present embodiment will be described with reference to Figs. 1 to 13. The information and communication system 1 according to the present 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 described in Patent Document 1 and Non-Patent Document 1 above.

[0015] SAGA BC In system 100, the cost of sending e-mails is mutually paid with virtual currency (digital currency) to prevent spam attacks. Generally, when a legitimate e-mail is sent to a legitimate e-mail address, the e-mail is legitimately received, so the number of e-mails sent matches the number of e-mails received. On the other hand, many of the e-mails sent in large quantities to random addresses by spammers are not legitimately received. As a result, the number of e-mails sent by spammers does not match the number of e-mails 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 incur the cost of replenishing their virtual currency. As a result, it is possible to prevent spam attacks by spammers.

[0017] Here, the definitions of terms used in this embodiment are shown below. A "blockchain" is a type of distributed database, and data is stored in units called blocks in sequence. Each block records a hash value up to the previous block. 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 Decentralised Generalised 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 of wallets, from web wallets that are stored online to cold wallets that are stored on a device that is isolated from the computer network. Virtual currency users manage 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 that transfers cryptocurrency signs a transaction that describes 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 one block that can be recorded on the blockchain and recording it at the top 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 it on the blockchain, the transaction history is confirmed in an irreversible manner. It takes several minutes from the issuance of a transaction to its confirmation.

[0023] Next, SAGA BC The configuration of an information communication system 1 of the present embodiment based on the system 100 will be described. FIG. 1 is a system outline diagram of the information communication system of the present embodiment. The information communication system 1 is a SAGA BCThe system configuration is based on system 100 and includes information and communication devices 10 (10a, 10b) that are 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 the information and communication devices 10a, 10b.

[0024] For example, when an e-mail is sent from an e-mail address set in one e-mail account used by one user as a sender to an e-mail address set in another e-mail account used by another user as a receiver, that is, when an e-mail is sent from the information communication device 10a to the information communication device 10b as shown in FIG. 1, the outgoing e-mail created by the information communication device 10a is sent to the information communication device 10b via the e-mail sending server 11a for the sender and the e-mail receiving server 11b for the receiver. This series of e-mail transmissions is performed by a general method, for example, via an SMTP server or a POP3 server. In the information communication device 10a, a remittance transaction of virtual currency is generated at the same time as the e-mail is sent, and is broadcast to the blockchain 12. The remittance transaction generated at this time indicates the remittance of a predetermined amount of virtual currency from the wallet of the sender, who is the user of the information communication device 10a, to the wallet of the receiver, who is the user of the information communication device 10b.

[0025] The information communication device 10b receives the e-mail (temporarily received at this stage) and accesses the blockchain 12 to check the deposit status of the e-mail, such as whether the virtual currency has been deposited in the user's wallet or whether the deposit amount is a predetermined amount or more. Only when the deposit status is appropriate, such as when the deposit is confirmed or when the deposit is more than a predetermined amount, the e-mail is received as a legitimate e-mail and displayed in the inbox or displayed in a state of being sorted as a legitimate e-mail. Note that when the deposit status is inappropriate, such as when the deposit is not confirmed or the deposit is less than a predetermined amount, the e-mail may be unconditionally discarded or moved to the trash, or may be displayed in the inbox once and then displayed in a manner that the recipient can understand that the e-mail does not contain any deposit of virtual currency (for example, an alert display, a highlight display, a display in a different color, etc.).

[0026] In the above, for the sake of clarity, one-way information communication has been described in which an information communication device 10a in which one account (one mail account and one wallet account) used by one user is set as the sender sends e-mail and transfers virtual currency to an information communication device 10b in which another account (another mail account and another wallet account) used by another user is set as the receiver, and e-mail is received and the deposit of virtual currency is confirmed by the information communication device 10b used by the other user. However, both the information communication device 10a used by the one user and the information communication device 10b used by the other user have the function of sending and receiving e-mail in both directions, and also have the function of transferring virtual currency and confirming the deposit, etc.

[0027] In the information and communication system 1 shown in Fig. 1, a mail account for sending and receiving e-mails 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 mail account held by a mail client. In other words, the mail client links a virtual currency wallet account to the email address set in the mail account.

[0028] A unique virtual currency called 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 an e-mail (transferred when sending an e-mail, or refunded when receiving a legitimate e-mail). Note that existing virtual currencies such as Bitcoin and Ethereum may be used as the MSC.

[0029] The main functions of the information and communication system 1 are implemented in a mailer installed in the information and communication devices 10a and 10b. A typical mailer is software for sending and receiving e-mail, and manages sending and receiving from one or more e-mail addresses. In the information and communication system 1, the functions required for the information and 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 e-mail, it has the function of verifying the wallet account corresponding to the destination e-mail address. (4) Incoming mail / deposit MSC support function It has the function of matching received e-mails with deposited MSCs, and the function of storing that data. (5) Spam filtering function Depending on the amount of the MSC deposit corresponding to each received email, the email can be displayed, sorted into the spam folder, or deleted. (6) Money transfer function It has the function of sending MSC from a wallet account corresponding to one's own email account, and the function of determining the amount to be sent (hereinafter, the amount of MSC to be sent). (7)Mining function When there is a shortage of MSC to send when sending an email, the MSC is replenished by mining transactions of MSC issued by many users. SPAMers can also replenish their MSC using this function, but this requires a lot 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 sending and receiving e-mails, that is, which e-mail account sent e-mail to which e-mail account, from the transaction history of MSC, that is, which wallet account sent MSC to which wallet account. In other words, even in an open system environment where centralized management was not possible in the past, such as e-mail 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 page rank algorithm described below from the history data of sending and receiving emails, and by determining which accounts are spammers based on the evaluation.

[0032] The PageRank algorithm is used to rank web pages, for example in search engine search results. The algorithm considers the number and quality of links to a page to roughly estimate the importance of a website. Initially, all pages are given an equal rank score. Then, the rank score of each page is recalculated based on the link structure, and this process continues until there is little change in the rank score. The PageRank calculation is done using matrix operations. The final rank of each page is obtained 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 the links. This algorithm is important for effectively organizing information on the web and allowing users to access more important content. In calculating PageRank, more accurate rankings can be achieved by considering not only the number of links but also how reliable and high-quality those links are.

[0033] The account evaluation algorithm in this embodiment, which applies this PageRank algorithm, is called MARA (Mail Account Rank Algorithm). The PageRank algorithm finds a score value that represents 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), creates a network graph in which accounts are nodes and 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 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 transfer the virtual currency, PR(T1) to PR(Tn) are score values ​​indicating the evaluations 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 destination accounts to which the other accounts T1 to Tn transferred the virtual currency.

[0036] Since spammers send large volumes of spam emails unilaterally (with almost no replies) to many accounts, they inevitably get a low score in MARA, resulting in 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 email to an unspecified number of people, and if the email is judged to be spam by the recipient, the MSC sent to the recipient is not refunded. As a result, the spammer is unable to send spam emails. In contrast, with 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 there is a high possibility that the MSC amount of e-mails sent will be returned as is, compared to spammers.

[0037] SAGA BC System 100 employs a method of suppressing spam mail by requiring a specified 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 as nodes and deposit / withdrawal information as edges are extracted from the blockchain 12 to generate a network graph. Here, accounts are regarded as nodes, and N nodes corresponding to all of the number N of accounts of users who use the information and communication system 1 are created. Each node has a node ID (account ID) and information on the amount of MSC held. In addition to this, the node may have information on the type of node (general account / SPAMer) and rank order. In addition, in the information and communication system 1, when an e-mail is sent, MSC is transferred from a wallet account corresponding to the sender to a wallet account corresponding to the recipient of the e-mail, and this MSC transfer information is treated as an edge and combined with the above-mentioned node to create a directed graph. If the recipient of the e-mail determines that the received e-mail is not a spam e-mail but a legitimate e-mail, the recipient refunds the amount of MSC received at the time of receiving the e-mail to the sender of the e-mail, so two edges are created for one e-mail, one at the time of sending and one at the time of refund. If the recipient of the e-mail determines that the received e-mail is a spam e-mail, the MSC is not refunded, so only one edge is created for one e-mail.

[0039] Figure 2 is an image of a network graph created from e-mail 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 e-mail transmission.

[0040] FIG. 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), other remittance source accounts that have made remittances of MSC are T1 to Tn (e.g., accounts C, D, E, F, and Z1 to Z3 in FIG. 4). Based on the score values ​​of the other accounts (numbers shown as % in FIG. 4, and corresponding to PR(C), PR(D), PR(E), PR(F), and PR(Z1) to PR(Z3)), the score value PR(B) of the one account is calculated, and each score value of the other accounts that affect the score value PR(B) of the one account is divided by C(Tn), which is the number of remittance destination accounts to which Tn has remitted (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-Z3 in Fig. 4) who is sending money to Account B as one of a huge number of recipients, the impact of Tn on the score of Account B will be minimal. On the other hand, if Tn is a regular user (C, D, E, F in Fig. 4), then Tn will be sending money to Account B as one of a normal number of recipients, and so the impact of Tn on the score of Account B will be large.

[0042] If an account only sends e-mails unilaterally, like a spammer, the score 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 of each node for the graph of nodes and edges in Figure 3 using the algorithm shown in formula (1).

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

[0044] In the information and communication system 1, a user with a low evaluation account is required to pay a higher transmission cost when sending an e-mail, so that a spammer cannot send spam e-mail. Therefore, in this embodiment, the MSC amount corresponding to the score value obtained above is set as the transmission MSC amount required when sending. That is, for example, in the example of FIG. 4, when an account Z1 with a low evaluation sends an e-mail, the e-mail cannot be received as a legitimate e-mail unless a large transmission MSC amount is set according to the score value (low) or score rank (low). On the other hand, when an account B with a high evaluation sends an e-mail, the e-mail can be received as a legitimate e-mail if a small transmission 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 e-mails, such as account B, the transmission MSC amount is refunded as it is, so even if a large MSC is required when sending an e-mail, there is almost no impact, but in the case of a user who is a spammer, such as account Z1, the transmission MSC amount is not refunded, so mining or the like is required to obtain the transmission MSC amount, and as a result, it becomes possible to eliminate spammers.

[0045] In this embodiment, the MARA process is executed on the MARA platform. The score value results and score ranking information at this time are also managed on the MARA platform. The MARA platform may be incorporated, for example, as an add-on function of a mailer, so that calculations can be performed individually 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 evaluation (score value) calculated by MARA may be made available for reference from the accounts of all users who use the information and communication system 1.

[0046] The following describes the configuration when 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 the information communication device in the information communication system according to this embodiment. First, the process when sending an e-mail 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 the operation of the sender of the e-mail, a sending e-mail creation unit 22 that creates an e-mail for sending in response to the input operation, an e-mail sending unit 23 that sends the created e-mail for sending to the e-mail sending server 11a, a correspondence information storage unit 24 that stores the respective e-mail addresses of the sender and the recipient (the e-mail address of the sender who is the sender and the e-mail address of the destination who is the recipient) in association with a wallet account, 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 MSC, and signs the generated remittance transaction using private key information stored in the private key storage unit 25 and broadcasts it to the blockchain 12. These configurations function in the process when sending an e-mail.

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

[0048] The sending MSC amount set here is the remittance amount required to have the email to be sent 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 be made variable by the sender as necessary.

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

[0050] Next, the process when receiving an e-mail will be described. In FIG. 5, the information communication device 10 includes a mail receiving unit 28 that receives an e-mail addressed to the recipient from the mail receiving server 11b, a reception control unit 29 that reads out the wallet account corresponding to the sender's e-mail address from the corresponding information storage unit 24 from the e-mail received by the mail receiving unit 28 and queries the blockchain 12 to confirm the presence or absence of an MSC remittance from the sender and / or the remittance amount, and a received e-mail processing unit 30 that displays the received e-mail as a legitimate e-mail if there is an MSC remittance from the sender or if the remittance amount is equal to or exceeds a preset threshold (hereinafter referred to as a received MSC threshold), and otherwise performs a process such as discarding the received e-mail as an unauthorized e-mail. These configurations function in the process when receiving an e-mail.

[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 receiving unit 28. At the same time, it extracts the wallet account from the recipient's own email address which is the destination of the email. 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 incoming mail processing unit 30, which receives the information about the e-mail and the information about the deposit status, performs predefined processing on the received e-mail depending on the deposit status (whether or not a deposit has been made, or whether or not a deposit above a predetermined amount has been made) (for example, displaying it in the inbox normally, displaying it in the inbox together with information about 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 regulated according to the amount of the deposited MSC. For example, the received e-mail may be sorted into different folders according to the amount of the deposit, or if a predetermined amount or more has been deposited, it may be highlighted, and if the amount is less than the predetermined amount, it may be displayed normally. In this way, if there is an urgent matter, it is possible to send a larger amount of MSC to encourage the user to check the e-mail as a priority.

[0054] Furthermore, information from the rank storage unit 52 of the MARA platform 50 may be read to specify the processing of the received mail processing unit 30 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 an email may be highlighted when the score value is equal to or greater than a predetermined value or the score ranking is higher than a predetermined rank, and displayed normally when the score value is less than the predetermined value or the score ranking is lower than a predetermined rank.

[0055] Here, as described above, the reception control unit 29 judges whether the amount of MSC remitted from the sender is equal to or greater than the reception MSC threshold and passes the judgment result to the reception mail processing unit 30. The reception MSC threshold is calculated, for example, by a function f (rank order) that uses the rank order of the sender's account stored in the rank storage unit 52 as an argument. The reception MSC threshold is generally determined by the threshold calculated by the function f, but may be arbitrarily variable by the receiver as necessary. As described above, if the transmission MSC amount and the reception MSC threshold are calculated by the same function f, the transmission MSC amount and the reception MSC threshold will be the same value, so that if the transmission MSC amount is deposited from the sender's wallet account to the receiver's wallet account when the email is sent, the email will be received as a legitimate email.

[0056] Next, the process of refunding when an e-mail is received will be described. In Fig. 5, the information communication device 10 has a refund control unit 31 that generates a remittance transaction for sending the MSC from the wallet account of the destination (recipient) to the wallet account of the sender (sender) in order to refund the MSC deposited when the e-mail is received, according to the process contents of the received e-mail executed by the received e-mail processing unit 30 and the operation contents performed by the recipient at the input / output unit 21, 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.

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

[0058] The refund process by the refund control unit 31 is similar to the remittance process performed when sending an e-mail, and the refund control unit 31 accesses the correspondence information storage unit 24 and extracts a wallet account from the email address of the sender who is the sender of the received e-mail. A remittance transaction (hereinafter referred to as a refund transaction) of the refund amount determined above is generated from the recipient's own wallet account, which is the destination of the e-mail, to the sender's wallet account, and is 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 the fact. If certain conditions are met, the refund amount may be set to any amount less than the deposited amount, and if another condition is 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 currently received e-mail is not spam but 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 less than the deposited amount (e.g., half the amount). If it is determined that the received e-mail 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 provided 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 provided with a MARA calculation unit 51 that creates a network graph as described in Figs. 2 to 4 and performs calculations using MARA, 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, 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 information on transactions managed on the blockchain 12 for each wallet account of the user. As shown in FIG. 8(A), information on the wallet account of the sender of the MSC and the wallet account of the recipient are consecutively described in each transaction 1 to N. The transactions acquired here may be all transactions on the blockchain 12, transactions corresponding to a period arbitrarily set by the user, or transactions of an account arbitrarily set by the user and accounts related to the 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 sender of the MSC and the wallet account of the recipient of the MSC 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 the MSC remittance as edges. The extracted edges are shown as arrows in FIG. 9(A). This makes it possible to recognize the relationship between which wallet account the MSC moved from and to as a graphic. By performing this process on all acquired transactions, a network graph showing a network structure as shown in FIG. 9(B) is generated using the nodes and edges.

[0063] Returning to Fig. 8, when a network graph as shown in Fig. 9(B) is generated (corresponding to Fig. 8(B)), the MARA calculation unit 51 executes MARA shown in formula (1) (Fig. 8(C)). By the MARA calculation of formula (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] In addition, the MARA calculation processing by the MARA calculation unit 51 may be performed at any timing in accordance with the user's instructions, or may be performed at a preset timing, or may be performed 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 flow chart showing the process of sending an e-mail (MSC remittance) in the information communication device according to this embodiment. In FIG. 10, first, the sending e-mail creation unit 22 creates a sending e-mail in response to the operation of the input / output unit 21 performed by the sender (S1). The e-mail sending unit 23 sends the created sending e-mail to the e-mail sending server 11a (S2). At the same time that the sending e-mail is handed over to the e-mail sending unit 23 in S2, the remittance control unit 27 receives the e-mail address of the destination, which is the recipient of the sending e-mail (S3). The remittance control unit 27 accesses the correspondence information storage unit 24, and extracts wallet accounts corresponding to the respective e-mail addresses from the e-mail address of the destination, which is the recipient, and the sender's own e-mail address, which is the sender (S4). The remittance control unit 27 queries the MARA platform 50, calculates the amount of sending MSC that can be received as a legitimate e-mail by the recipient based on its own rank (S5), and compares the amount of sending MSC with the amount of MSC held in the wallet account of the sender (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 (the sender) to the destination wallet account (the receiver) (S7). 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 process of sending the email.

[0066] As described above, in S6, if the amount of MSC held is less than the amount of MSC sent, the e-mail may not be sent, or the amount of MSC sent may be changed to within the range of the amount of MSC 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 a spam e-mail and thus be treated as an invalid e-mail.

[0067] FIG. 11 is a flowchart showing a process when an e-mail is received in the information communication device according to the present embodiment. In FIG. 11, first, the e-mail receiving unit 28 receives an e-mail from the e-mail receiving server 11b (S1). The reception control unit 29 receives the e-mail address of the sender of the received e-mail (S2). The reception control unit 29 accesses the correspondence information storage unit 24 and extracts wallet accounts corresponding to the respective e-mail addresses from the e-mail address of the sender as the sender and the e-mail address of the recipient as the destination (S3). The reception control unit 29 queries the blockchain 12 about the deposit status of the MSC from the wallet account of the sender as the sender to the wallet account of the recipient as the destination (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 e-mail processing unit 30. When the received e-mail processing unit 30 receives a determination result that the amount of the deposited MSC is equal to or greater than the received MSC threshold, the received e-mail processing unit 30 executes a process to display the received e-mail as a legitimate e-mail (S6). If a determination result is received that the amount of the deposited MSC is less than the received MSC threshold, the received e-mail is treated as an unauthorized e-mail and processing is executed so that the e-mail is not displayed (S7), and the e-mail reception processing is completed.

[0068] FIG. 12 is a flowchart showing the refund process in the information communication device according to the present embodiment. In FIG. 12, first, the refund control unit 31 receives the processing mode of the received mail processing unit 30 in the process of receiving an e-mail, 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 judges whether the received processing mode is the processing mode when a legitimate e-mail is received, or whether the evaluation information is a predetermined evaluation or higher (S2). If it is determined in S2 that the received processing mode is the processing mode when a legitimate e-mail is received and the evaluation satisfies the predetermined evaluation, the refund control unit 31 sets the refund amount to an amount equal to the MSC deposited when the e-mail is received (S3). On the other hand, if it is determined in S2 that the received processing mode is not the processing mode when a legitimate e-mail is received, or the evaluation does not satisfy the predetermined evaluation, the refund control unit 31 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 as the sender and the user's email address as the destination of the recipient (S5). A refund transaction is generated for sending the MSC from the user's wallet account as the destination of the received email to the wallet account of the sender as the sender (S6). The private key information is read from the private key storage unit 25 and the generated refund transaction is signed (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 by MARA of 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 described above, the MARA platform 50 may be implemented on the blockchain 12, or on a dedicated device for the MARA platform 50 accessible from the information communication device 10, or on a web server, mail server, etc. In this case, each of the processing units 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 to refer to the rank information.

[0072] In the above, one email account is associated with one wallet account, but 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 e-mail, a remittance transaction is generated in which a specified MSC is transferred to the destination account in conjunction with the sending of the e-mail, and this is broadcast to the blockchain 12. When receiving an e-mail, if the e-mail is determined to be a legitimate e-mail, a refund transaction is generated in which the MSC deposited in conjunction with the receipt of the e-mail is returned 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 the score value, so that the accounts of system users are evaluated from the deposit and withdrawal status of the MSC, and as a result, it is possible to identify accounts of users 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 applies the page rank algorithm for ranking web pages in search results of a search engine to the SAGA BC The accounts of users of the system 100 can be properly evaluated, and based on the evaluation results, the costs required for sending e-mail can be appropriately changed, thereby eliminating spammers and suppressing SPAM mail.

[0075] In addition, the sending MSC amount required to have an email sent 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 that the appropriate sending and receiving amounts for a normal user can be calculated individually based on the account evaluation. EXAMPLES

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

[0077] FIG. 15 is a NS chart showing the main routine of a simulation for verifying the spammer discrimination accuracy 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, there are 10 spammers and 990 general accounts. (2) Transmission and remittance loop A regular account will send an email to 15 randomly selected regular accounts using an account other than itself and spammers, and will simultaneously transfer 1 MSC. (3) Refunds The email receiver refunds the MSC to the email sender based on an arbitrary refund probability 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) Transmission and remittance loop At the same time as sending the email, the SPAMer will transfer 1 MSC to the general accounts of 30 randomly selected people. (6) Refunds The general account that receives the email refunds the MSC sent by the spammer based on an arbitrary refund probability in FIG. 14(A). (7) SPAMer Loop Repeat this process until 10 spammers have sent emails to 30 randomly selected public accounts. Note that the spammers will not mine. (8) Rank calculation Calculate the rank of all accounts based on the data obtained in steps (1) through (7).

[0078] The above simulation experiment was conducted with 1000 accounts, combining the refund probability of normal accounts and the refund probability of spammers as shown in Figure 14 for a total of 64 patterns. 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 is set to 15. Also, since the number of emails sent by spammers is unknown, this time the number of emails sent per day was set to 30. The number of accounts was set to 1000, and 1% of those, or 10 accounts, were set to spammers.

[0079] First, all accounts send and receive emails for one day. From the results for that day, a network graph is output with accounts as nodes and MSC transfers and refunds as edges. For that graph, MARA calculates the rank scores of all accounts using python's networkX. Based on the calculated scores, the accounts are ranked in order of highest rank score, and rank ranking information is assigned to the nodes. Then, based on the assigned rank ranking information, the amount of MSC sent that needs to be paid when sending email changes. We verify whether SPAMers are ranked lower.

[0080] Fig. 16 is a diagram showing the results of a simulation verifying the accuracy of spammer determination 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 refunding money to spammers is extremely low at 80% or more in an actual environment, this embodiment shows that 92% of spammers are ranked low. Also, when the probability of refunding money to spammers is 80% or more, the spammer sends 30 e-mails and the associated MSCs and receives a refund, so that the spammer is ranked higher than a general account.

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

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

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

[0084] 64 combinations of the general account and the probability of refunding to the spammer in Fig. 14(A) are repeated. A higher-ranked account requires less amount of MSC to send when sending an e-mail, and a lower-ranked account requires more amount of MSC to send when sending an e-mail. Here, the amount of MSC sent is set to rank. Since the rank score output by MARA depends on the direction and number of edges, the rank score of an account changes depending on the percentage of MSC refunded. Therefore, the probability of MSC refund from a general account to another general account and from a general account to a spammer is set to 0, 1, 20, 40, 60, 80, 99, and 100%, respectively. In addition, a general account sends 15 e-mails and a spammer sends 30 e-mails in a day, and this is done for 10 days. A total of 64 patterns are performed 10 times for 10 days, and the average results of the 10 times are output to a csv file. In addition, a similar experiment is performed without MARA as a comparison to verify the effectiveness of MARA.

[0085] As a result of the simulation using MARA, Fig. 18(A) shows the average amount of virtual currency held by spammers, and Fig. 18(B) shows the average number of emails sent by spammers. Fig. 18(A) shows that the average amount of virtual currency held by spammers drops sharply when the probability of refunding to spammers is 99% to 80%, and when it is 60% or less, the amount of virtual currency held is less than 100. In addition, it was found that the average amount of virtual currency held by spammers when the probability of refunding to general accounts is 0-1% and the probability of refunding to spammers is 80% is about three times the amount held when the probability of refunding 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, and spammers are 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 to a spammer is 80% or less, the amount of virtual currency held by the spammer decreases, and if it is 60% or less, the amount of virtual currency held by the spammer falls below 100, making it impossible to pay the amount of MSC required for sending and making it impossible to send spam emails. It also becomes clear that the probability of refunds between regular accounts does not have a significant effect on the number of emails sent by a spammer.

[0087] As a result of the simulation without MARA, Fig. 19(A) shows the average amount of virtual currency held by spammers, and Fig. 19(B) shows the average number of emails sent by spammers. Fig. 19(A) shows that the average amount of virtual currency held by spammers was not such that spammers were unable to send emails, regardless of the probability of refunding to spammers. Fig. 19(B) shows that the average number of emails sent by spammers was 30 emails sent at all refund probabilities. These results show that when MARA is not used, even small values ​​of the probability of refunding to spammers, such as 0-1%, cannot reduce the number of spam emails in a short period of time, and a long period of time is required to suppress spam. It also shows that the probability of refunding between general accounts has almost no effect on the number of emails sent by spammers. Comparing when MARA is used and when it is not used, it is shown that using MARA reduces the average amount of virtual currency held by spammers 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 refund to a general account increases. Figure 20(B) shows that the number of emails sent by general accounts does not decrease when MARA is not used.

[0089] The simulation results confirmed that by using MARA, it is possible to set an appropriate MSC amount for spammers, and that spam mail can be significantly reduced when the probability of refunding the payment to the spammer is 60% or less. The reason for this is thought to be largely related to the MSC amount sent according to rank. This is thought to be because MARA forces spammers to pay large amounts of MSC amount sent, and therefore reduces the amount of virtual currency held by the spammer more, even if there is a certain probability of refund. By using MARA, it is possible to suppress 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 Corresponding 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 Section 50 MARA Platform 51 MARA Processing Department 52 Rank Memory Unit

Claims

1. The computer a mail sending unit for sending email from one account to another account; a remittance control unit that generates a remittance transaction for remitting virtual currency from the one account to the other account when the email sending unit sends the email and broadcasts the transaction to a blockchain; a mail receiving unit for receiving emails sent to one account from another account; a reception control unit that, when the email receiving unit receives the email, accesses the blockchain to confirm the deposit status of the virtual currency from the other account to the one account, and receives the email as a legitimate email if the confirmed deposit amount is equal to or greater than a predetermined threshold; In an information and communication system including at least an information and communication device that functions as a refund control unit that, when the reception control unit receives the legitimate email, generates a refund transaction for refunding the virtual currency from the one account to the other account in accordance with the virtual currency remittance transaction generated when the email was sent, and broadcasts the refund transaction to the blockchain, an evaluation unit 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 to calculate a score value and evaluates the target account based on the score value; The information and communication system is characterized in that the evaluation unit has a function calculation means for calculating the score value of the target account that is the subject of the calculation using at least the number of remittance accounts from which the virtual currency was transferred from accounts other than the target account that is the subject of the calculation to the target account that is the subject of the calculation, and the score value of the remittance source from which the virtual currency was transferred from accounts other than the target account that is the subject of the calculation to the target account that is the subject of the calculation, and performs the calculation of the evaluation based on the score value of the target account calculated by the calculation means.

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

3. 3. The information and communication system according to claim 1, An information and communication system characterized in that the function of the calculation means in the evaluation unit is a function that, when evaluating the target account, uses the score value of the other account as an argument and calculates the score value of the target account as a return value.

4. 3. The information and communication system according to claim 2, When the evaluation unit evaluates the target account, [0010] 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 remittance sources that remitted the virtual currency to the target account, and C(Tn) is the number of remittance destination accounts to which the other accounts T1 to Tn remitted the virtual currency. An information and communication system, comprising: a score value calculated based on the formula (1).

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

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

7. The computer a mail sending unit for sending email from one account to another account; a remittance control unit that generates a remittance transaction for remitting virtual currency from the one account to the other account when the email sending unit sends the email and broadcasts the transaction to a blockchain; a mail receiving unit for receiving emails sent to one account from another account; a reception control unit that, when the email receiving unit receives the email, accesses the blockchain to confirm the deposit status of the virtual currency from the other account to the one account, and receives the email as a legitimate email if the confirmed deposit amount is equal to or greater than a predetermined threshold; an information communication device that functions as a refund control unit that, when the reception control unit receives the legitimate email, generates a refund transaction for refunding the virtual currency from the one account to the other account in accordance with the virtual currency remittance transaction generated when the email was sent, and broadcasts the refund transaction to the blockchain; an evaluation unit that analyzes the deposit and withdrawal status of the virtual currency stored in the blockchain for each target account of a user to calculate a score value and evaluates the target account based on the score value; The information and communications device is characterized in that the evaluation unit has a function calculation means for calculating the score value of the target account that is the subject of the calculation using at least the number of remittance accounts from which the virtual currency was transferred from accounts other than the target account that is the subject of the calculation to the target account that is the subject of the calculation, and the score value of the remittance source from which the virtual currency was transferred from accounts other than the target account that is the subject of the calculation to the target account that is the subject of the calculation, and performs the calculation of the evaluation based on the score value of the target account calculated by the calculation means.

8. Computer, A mail sending unit for sending email from one account to another; a remittance control unit that generates a remittance transaction for remitting virtual currency from the one account to the other account when the email sending unit sends the email, and broadcasts the transaction to a blockchain; an email receiving unit for receiving emails sent to one account from another account; a reception control unit that, when the email receiving unit receives the email, accesses the blockchain to confirm the deposit status of the virtual currency from the other account to the one account, and receives the email as a legitimate email if the confirmed deposit amount is equal to or greater than a predetermined threshold; a refund control unit that, when the reception control unit receives the legitimate email, generates a refund transaction for refunding the virtual currency from the one account to the other account in accordance with the virtual currency remittance transaction generated when the email was sent, and broadcasts the refund transaction to the blockchain, Analyzing the deposit and withdrawal status of the virtual currency stored in the blockchain for each target account of a user, calculating a score value, and making a computer function as an evaluation unit that evaluates the target account based on the score value; The information and communications program, characterized in that the evaluation unit has a function calculation means for calculating the score value of the target account that is the subject of the calculation using at least the number of remittance accounts from which the virtual currency was transferred from accounts other than the target account that is the subject of the calculation to the target account that is the subject of the calculation, and the score value of the remittance source from which the virtual currency was transferred from accounts other than the target account that is the subject of the calculation to the target account that is the subject of the calculation, and performs a calculation of the evaluation based on the score value of the target account calculated by the calculation means.

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