Money transaction system, computer program, and money transaction method

Abstract

To provide a money transaction system, a computer program, and a money transaction method that enable safe money transactions even offline.SOLUTION: A first information terminal 20 comprises first acquisition means 26 that acquires data on a transaction amount in a money transaction, payment means 26 that decreases a balance of balance data according to the data on the transaction amount, and first display means 26 that displays payment completion image information 42 including security information on a first image display unit 23 when the decreasing of the balance of the balance data is completed. A second information terminal 10 comprises second image reading means 16 that causes a second image reading unit 11 to read the payment completion image information 42, second acquisition means 16 that acquires the security information or information based on the security information from the payment completion image information 42, and receiving means 16 that increases a balance of the balance data. The receiving means 16 determines whether to increase the balance of the balance data based on the security information.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a monetary transaction system, a computer program, and a monetary transaction method that enable secure monetary transactions based on monetary data such as electronic money between two terminals even offline. [Background technology]

[0002] Conventionally, a monetary transaction system has been disclosed in which, in an environment in which an information terminal such as a smartphone carried by a purchaser and an information terminal held by a seller can both connect to a monetary transaction server via a network, the purchaser's information terminal and the seller's information terminal each access the server, thereby enabling monetary payment processing based on monetary data to be performed between the purchaser's information terminal and the seller's information terminal (for example, Patent Document 1). Furthermore, Patent Document 2 discloses that the server stores the expiration date linked to the payment token in a storage unit, and when the expiration date has passed, the payment becomes impossible. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-062125 [Patent Document 2] Patent No. 6928151 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, in an offline environment where network communication is not available, each information terminal cannot access the monetary transaction server on the network, and therefore monetary transactions based on monetary data cannot be carried out, which is a problem. Furthermore, in Patent Document 2, in an offline environment where network communication is not available, the expiration date stored in the server cannot be confirmed, and it is not possible to determine whether or not payment can be made based on the expiration date.

[0005] The present invention aims to provide a monetary transaction system, computer program, and monetary transaction method that can safely perform monetary transactions based on monetary data between two information terminals even in an environment where a network is not available. [Means for solving the problem]

[0006] The monetary transaction system according to the present invention comprises a first information terminal having a first image display unit and a first image reading unit, and a second information terminal having a second image display unit and a second image reading unit, and executes a monetary transaction based on monetary data between the first information terminal and the second information terminal offline, wherein the first information terminal comprises a first storage means for storing balance data held by the first information terminal, a first acquisition means for acquiring data on a transaction amount in the monetary transaction, a payment means for deducting the balance of the balance data stored in the first storage means in accordance with the data on the transaction amount acquired by the first acquisition means, and a payment means for deducting the balance of the balance data stored in the first storage means when the deduction of the balance by the payment means is completed, and The second information terminal has a first display means for displaying payment completion image information including information based on the first security information on the first image display unit, and the second information terminal has a second storage means for storing balance data held by the second information terminal, a second image reading means for causing the second image reading unit to read the payment completion image information displayed by the first information terminal, a second acquisition means for acquiring the first security information or information based on the first security information from the payment completion image information, and a receiving means for increasing the balance of the balance data stored in the second storage means according to the transaction amount when the payment completion image information is read, and the receiving means determines whether to increase the balance of the balance data based on the first security information. In the above offline monetary transaction system, the second information terminal may have a second display means for displaying image information for transaction cancellation on the second image display unit when the receiving means is prohibited from increasing the balance of the balance data based on the first security information, and the first information terminal may have a first image reading means for causing the first image reading unit to read the image information for transaction cancellation displayed by the second information terminal, and a cancellation means for canceling the reduction of the balance of the balance data stored in the first storage means made by the payment means when the image information for transaction cancellation is read. In the above offline monetary transaction system, the first security information is information indicating the expiration date of the payment completion image information, and in the second information terminal, the receiving means can be configured to determine whether the expiration date of the payment completion image information has passed based on the first security information, and if the expiration date of the payment completion image information has passed, prohibit an increase in the balance of the balance data stored in the second storage means. In the above offline monetary transaction system, the information based on the first security information is payment completion information encrypted with the public key of the second information terminal, and in the second information terminal, the second storage means stores a private key corresponding to the public key, and the receiving means decrypts the payment completion information encrypted with the public key with the private key, and when it confirms that payment has been completed at the first information terminal based on the decrypted payment completion information, it allows the balance of the balance data stored in the second storage means to be increased. In the above offline monetary transaction system, the second information terminal has an input means for inputting the transaction amount, and a second display means for generating transaction information including the transaction amount input by the input means and transaction start image information including second security information, and displaying the transaction start image information on the second image display unit of the second information terminal, the first information terminal has a first image reading means for causing the first image reading unit to read the transaction start image information displayed on the second image display unit of the second information terminal, and in the first information terminal, the first acquisition means can be configured to acquire the transaction information and the second security information from the transaction start image information. In the above offline monetary transaction system, the second security information is information indicating the expiration date of the transaction start image information, and in the first information terminal, the payment means can be configured to determine whether the expiration date of the transaction start image information has passed based on the second security information, and if the expiration date of the transaction start image information has passed, prohibit the reduction of the balance of the balance data stored in the first storage means. In the above offline monetary transaction system, the second security information is the public key of the seller, and in the first information terminal, when the payment means has completed deducting the balance of the balance data, the first display means can be configured to encrypt the payment completion information based on the second security information, thereby making the encrypted payment completion information information based on the first security information, and display payment completion image information including the encrypted payment completion information on the first image display unit. In the above offline monetary transaction system, the payment completion image information may be displayed as an information code in which information cells arranged two-dimensionally form information units. A computer program according to a first aspect of the present invention is a computer program executed by a first information terminal in a financial transaction system having a first information terminal having a first image display unit and a first image reading unit, and a second information terminal having a second image display unit and a second image reading unit, and performing financial transactions based on financial data between the first information terminal and the second information terminal offline, the computer program executing: a first storage function that stores balance data held by the first information terminal; a first acquisition function that acquires data on the transaction amount in the financial transaction; a payment function that, when the user of the first information terminal approves payment of the transaction amount, reduces the balance of the stored balance data in accordance with the transaction amount; and a display function that, when the reduction of the balance of the balance data by the payment function is completed, displays first security information or payment completion image information including information based on the first security information on the first image display unit. A computer program according to a second aspect of the present invention is a computer program executed by the second information terminal in a financial transaction system having a first information terminal having a first image display unit and a first image reading unit, and a second information terminal having a second image display unit and a second image reading unit, and performing financial transactions based on financial data between the first information terminal and the second information terminal offline, the computer program having a second storage function for storing balance data held by the second information terminal, a second image reading function for causing the second image reading unit to read the payment completion image information displayed by the first information terminal when payment completion image information indicating that payment has been completed is displayed on the first information terminal, a second acquisition function for acquiring the first security information or information based on the first security information from the payment completion image information, and a receiving function for increasing the balance of the balance data held by the second information terminal according to the transaction amount when the payment completion image information is read, and the receiving function determines whether to increase the balance of the balance data based on the first security information. The offline monetary transaction method according to the present invention is a monetary transaction method for executing a monetary transaction offline based on monetary data between a first information terminal having a first image display unit and a first image reading unit, and a second information terminal having a second image display unit and a second image reading unit, wherein the first information terminal stores balance data held by the first information terminal, acquires data on the transaction amount for the monetary transaction, and, when the user of the first information terminal approves payment of the transaction amount, increases the balance in the balance data held by the first information terminal according to the transaction amount. The second information terminal stores the balance data held by the second information terminal, and when the second image reading unit reads the payment completion image information displayed by the first information terminal, the second information terminal determines based on the first security information whether to increase the balance of the balance data stored in the second information terminal, and when it determines to increase the balance data, the second information terminal increases the balance data according to the transaction amount. [Effects of the Invention]

[0007] According to the present invention, even in an environment where a network is not available, a monetary transaction based on monetary data can be safely carried out between two information terminals. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing the configuration of a monetary transaction system according to an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram illustrating a usage scenario of a monetary transaction system according to an embodiment of the present invention. [Figure 3] FIG. 2 is a block diagram of a seller terminal and a buyer terminal according to the present embodiment. [Figure 4] FIG. 10 is a diagram showing a transaction screen displayed on a seller terminal. [Figure 5] FIG. 10 is a diagram showing a charge screen displayed on a purchaser terminal. [Figure 6] FIG. 10 is a diagram showing a payment screen displayed on a purchaser terminal. [Figure 7] FIG. 10 is a diagram showing a payment completion screen displayed on the purchaser terminal. [Figure 8] FIG. 2 is a diagram for explaining an information code according to the present embodiment. [Figure 9] 1 is a flowchart showing offline monetary transaction processing according to the first embodiment (part 1). [Figure 10] 10 is a flowchart showing offline monetary transaction processing according to the first embodiment (part 2). [Figure 11] 10 is a flowchart showing offline monetary transaction processing according to the second embodiment (part 1). [Figure 12] 10 is a flowchart showing offline monetary transaction processing according to the second embodiment (part 2). DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment An embodiment of a monetary transaction system according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the configuration of a monetary transaction system 1 according to this embodiment, and FIG. 2 is a diagram illustrating a usage scenario of the monetary transaction system 1 according to this embodiment. As shown in FIGS. 1 and 2, the monetary transaction system 1 according to this embodiment includes mobile terminals 10 and 20 carried by two parties conducting a monetary transaction, respectively, and a server 30. As shown in FIG. 1, in an environment where network communication using an Internet line 2 or the like is available, the mobile terminals 10 and 20 can exchange information with the server 30 via wireless or wired communication. On the other hand, in this embodiment, as shown in FIG. 2, even in an environment where network communication is not available, it is possible to conduct a monetary transaction based on electronic money using the two mobile terminals 10 and 20.

[0010] In this embodiment, a scenario will be described in which a buyer purchases a product from a seller in a store and performs a financial transaction associated with the purchase using a seller's mobile terminal 10 (corresponding to a second information terminal in the present invention) and a buyer's mobile terminal 20 (corresponding to a first information terminal in the present invention). Here, the mobile terminal 10 carried by the seller is also referred to as a seller terminal 10, and the mobile terminal 20 carried by the buyer is also referred to as a buyer terminal 20. However, the financial transaction system 1 according to this embodiment is not limited to use when purchasing products. It can also be used for splitting the bill for dining and drinking, settling group travel expenses among members, collecting donations in a lump sum, sending money to family, and paying gifts. Furthermore, while the examples shown in FIGS. 1 and 2 illustrate a one-to-one relationship between a seller receiving electronic money and a buyer paying electronic money, this configuration is not limiting. For example, one person (e.g., the organizer of a dining and drinking bill) can also receive electronic money from multiple people (e.g., multiple participants in a dining and drinking bill).

[0011] FIG. 3 is a block diagram showing the configurations of the seller terminal 10 and the buyer terminal 20. The seller terminal 10 is an information terminal such as a smartphone, tablet, or laptop computer carried by the seller. As shown in FIG. 3, the seller terminal 10 includes a camera 11, a communication unit 12, a display 13, an input unit 14, a memory unit 15, and a calculation unit 16. The camera 11 reads information codes displayed on the buyer terminal 20. The communication unit 12 communicates with the server 30 in an environment where network communication is available. The display 13 displays information codes 41, including transaction information for monetary transactions such as the transaction amount, on the screen. The input unit 14 is used by the seller to input transaction information such as the transaction amount. The display 13 and the input unit 14 can also be integrated into a touch display. The memory unit 15 stores a program for conducting monetary transactions according to this embodiment and stores electronic money balance data used for offline monetary transactions. By executing the programs stored in the memory unit 15, the calculation unit 16 realizes a seller transaction function for performing electronic money transactions offline, and a balance data update function for updating the server balance data stored in the server 30 so that the terminal balance data stored in the seller terminal 10 matches the server balance data of the seller terminal 10 stored in the server 30, in an environment where network communication is available. The above programs can be executed in the seller terminal 10 in the form of an application or app. Each function of the seller terminal 10 is described below.

[0012] The seller transaction function of the seller terminal 10 generates an information code 41 containing transaction information as shown in FIG. 4 when the seller inputs the transaction amount via the input unit 14, and displays the generated information code 41 on the display 13. The information code 41 displayed by the seller transaction function includes transaction information such as a seller code for identifying the seller, a transaction code for identifying the transaction, transaction amount data, the seller's mobile phone number, and the product identification number of the seller terminal 10. In this embodiment, the buyer terminal 20 reads the information code 41 displayed by the seller terminal 10, thereby executing the electronic money payment. The transaction code is a unique code for each transaction, and can be, for example, an epoch second or a sequential number under certain management.

[0013] In this embodiment, the information code 41 includes a first timestamp indicating the transaction expiration date as the second security information. Including the first timestamp as the second security information in the information code 41 ensures transaction security even in offline payments. Conventionally, security information such as a timestamp is stored on a server, and a terminal acquires security information from the server and restricts the transaction using the acquired security information, or the server restricts the transaction using the security information stored on the server. In contrast, in this embodiment, since offline payments are made, the information code 41 indicating the start of the transaction includes the first timestamp as the second security information. The seller terminal 10 displays the information code 41 including the first timestamp, allowing the buyer terminal 20 to capture and read an image of the information code 41 and obtain the first timestamp from the read information code 41. This allows the purchaser terminal 20 to permit monetary transactions only within the validity period of the information code 41 (within a certain period of time from the time indicated by the first timestamp) based on the acquired first timestamp (by prohibiting monetary transactions after the validity period), thereby enabling offline monetary transactions to be carried out safely. The first security information will be described later.

[0014] Furthermore, in this embodiment, when payment is executed at buyer terminal 20, information code 42 (payment completion image information) indicating the completion of payment is displayed on display 23 of buyer terminal 20. In this case, the seller transaction function reads information code 42 displayed on buyer terminal 20 with camera 11, and increases the terminal balance data of electronic money stored in memory 15 according to the transaction amount. In this way, by reading information code 42 displayed on buyer terminal 20 indicating the completion of payment, seller terminal 10 can confirm that payment has been completed at buyer terminal 20, even when a monetary transaction based on electronic money is performed offline, and it becomes possible to properly complete the transaction at seller terminal 10.

[0015] In this embodiment, the information code 42 also includes a second timestamp as the first security information. The second timestamp is information indicating the reference time of the expiration date of the information code 42. The seller-side transaction function reads the information code 42 containing payment completion information, and before incrementing the electronic money terminal balance data stored in the memory unit 15, determines whether the expiration date, which is a certain time period after the time indicated by the second timestamp, has passed. If the expiration date of the information code 42 has passed, the seller-side transaction function prohibits the execution of a process to increment the electronic money terminal balance data stored in the memory unit 15. This prevents the balance data from being incremented using an information code 42 whose expiration date has passed, thereby enhancing the security of the transaction. On the other hand, if the expiration date based on the second timestamp has not passed, the seller-side transaction function can appropriately increment the terminal balance data by executing a process to increment the electronic money terminal balance data stored in the memory unit 15.

[0016] The balance data update function of seller terminal 10 updates server balance data stored in server 30 to match the terminal balance data of electronic money stored in seller terminal 10 in an environment where network communication such as Internet connection 2 is available. That is, in this embodiment, in an environment where seller terminal 10 and buyer terminal 20 are able to use network communication such as Internet connection 2, electronic money transactions can be conducted via server 30 as in the past, and server 30 stores the balance data of the seller carrying seller terminal 10 as server balance data. On the other hand, in an environment where network communication is not available, seller terminal 10 cannot access server 30, and therefore, when an offline monetary transaction according to this embodiment is conducted, the terminal balance data stored in memory unit 15 of seller terminal 10 and the server balance data stored in server 30 will no longer match. Therefore, when an offline monetary transaction is performed and an environment in which network communication is available is established, the balance data update function accesses the server 30 and updates the server balance data stored in the server 30 so that it matches the terminal balance data stored in the seller terminal 10.

[0017] The buyer terminal 20 is an information terminal such as a smartphone, tablet, or laptop computer carried by the buyer. As shown in FIG. 3 , the buyer terminal 20 includes a camera 21, a communication unit 22, a display 23, an input unit 24, a memory unit 25, and a calculation unit 26. The camera 21 reads an information code 41 containing transaction information displayed on the seller terminal 10. The communication unit 22 communicates with the server 30 in a network-enabled environment. The display 23 displays an information code 42 indicating payment completion on the screen. The input unit 24 allows the buyer to input payment information and other information. Note that the display 23 and the input unit 24 may be integrated into a touch display. The memory unit 25 stores a program for conducting monetary transactions according to this embodiment and also stores electronic money balance data. The calculation unit 26 executes the program stored in the memory unit 25 to realize a charging function for charging electronic money in a network-enabled environment and a buyer transaction function for performing electronic money-based monetary transactions offline. The above program can be executed in the form of an application or app on the purchaser terminal 20. Each function of the purchaser terminal 20 will be described below.

[0018] The charge function of the purchaser terminal 20 accesses the server 30 and charges electronic money in an environment where network communication is available. The charge function can be performed by a known method. For example, when charging electronic money by credit card payment, the charge function displays a screen on the display 13 for inputting the amount to be charged, as shown in FIG. 5(A). Then, when the purchaser inputs the charge amount, a charge confirmation screen is displayed, as shown in FIG. 5(B). If the purchaser approves the charge, the server 30 is accessed, and the terminal balance data stored in the purchaser terminal 20 is updated according to the charge amount.

[0019] The buyer's transaction function of the buyer's terminal 20 executes payment for the monetary transaction based on the information code 41 containing the transaction information displayed by the seller's terminal 10. Specifically, when the buyer's transaction function reads the information code 41 containing the transaction information displayed by the seller's terminal 10, it extracts the transaction information from the information code 41 and, based on the extracted transaction information, displays the transaction amount, balance, and balance after payment on the screen of the display 13, as shown in FIG. 6(A), for example. The buyer's transaction function also displays a payment button on the screen and requests approval of the payment for the transaction. When the buyer presses the payment button, the buyer's transaction function displays a payment confirmation as shown in FIG. 6(B). If the buyer approves the payment, the buyer's transaction function deducts the transaction amount from the terminal balance data stored in the memory unit 25 of the buyer's terminal 20 and completes the payment. In addition, if the transaction amount is greater than the balance in the terminal balance data, the purchaser's transaction function will indicate that the transaction cannot be executed and will display an error on the screen of display 13 (or may display such that the payment button cannot be pressed).

[0020] In this embodiment, the buyer's transaction function also has a security function that extracts a first timestamp from the information code 41 and determines whether or not to execute the payment based on the first timestamp. Specifically, if a certain amount of time has passed since the time indicated by the first timestamp, the buyer's transaction function prohibits the process of deducting the transaction amount from the terminal balance data stored in the memory unit 25 of the buyer's terminal 20, even if the buyer approves the payment. In this case, by generating the information code 41 again in the seller terminal 10, an offline monetary transaction can be performed within the deadline based on the newly updated first timestamp.

[0021] Furthermore, when payment is completed, the buyer's transaction function of the buyer's terminal 20 creates an information code 42 indicating the completion of payment, and displays the created information code 42 on the display 23, as shown in FIG. 7. This is because, in conventional online monetary transactions, the completion of payment at the buyer's terminal 20 can be confirmed at the seller's terminal 10 via the server 30, whereas in offline monetary transactions, it is not possible to confirm at the seller's terminal 10 whether payment at the buyer's terminal 20 has been completed. Therefore, by displaying such information code 42 indicating the completion of payment at the buyer's terminal 20 and having the seller's terminal 10 read the information code 42 indicating the completion of payment, it is possible to have the seller's terminal 10 confirm the completion of payment even in offline monetary transactions.

[0022] In particular, in this embodiment, the buyer's transaction function can include, in the information code 42 indicating payment completion, payment completion information indicating that the payment has been completed and a second timestamp indicating the expiration date of the information code 42. This allows the seller terminal 10 to confirm that the payment has been made at the buyer terminal 20 based on the payment completion information, and also determines, based on the second timestamp, whether the expiration date of the information code 42, which is a certain period of time from the time indicated by the second timestamp, has passed, and if the expiration date has passed, prohibits the process of increasing the terminal balance data stored in the memory unit 15 of the seller terminal 10, thereby improving the security of the transaction.

[0023] In this embodiment, the storage units 15 and 25 of the seller terminal 10 and the buyer terminal 20 pre-store personal information such as the seller's and buyer's account numbers, My Number, and biometric authentication information such as facial images. In this embodiment, the storage units 15 and 25 of the seller terminal 10 and the buyer terminal 20 store terminal balance data held by the seller terminal 10 and the buyer terminal 20, respectively. It is preferable to encrypt the terminal balance data stored in the storage units 15 and 25 to ensure security. For example, a key string representing the terminal balance data can be converted using a predetermined function f(x) and then encrypted using RSA encryption. To further enhance security, measures to make program disassembly difficult to understand are also effective (e.g., converting names in source code, such as class names, method names, and variable names, to names that are difficult for humans to read, encrypting strings containing functions, or inserting meaningless loops or goto statements to make the source code difficult to understand). Periodic program revision is also effective.

[0024] Server 30 is installed on Internet line 2 and has the function of exchanging data with seller terminal 10 and buyer terminal 20 and conducting electronic payments when seller terminal 10 and buyer terminal 20 can connect to Internet line 2. As described above, server 30 stores the balance data of seller terminal 10 and buyer terminal 20 as server balance data, and can perform an update process to match the server balance data when the terminal balance data of seller terminal 10 and buyer terminal 20 does not match the server balance data due to an offline financial transaction. When performing the update process, in order to prevent fraud, server 30 may refer to a transaction code or the like to check whether the amount increased at seller terminal 10 matches the amount decreased at buyer terminal 20 in a financial transaction between seller terminal 10 and buyer terminal 20.

[0025] Next, an information code 40 according to this embodiment will be described. The information code 40 includes the information code 41 and information code 42 described above, as well as the information code 43 described later, and the information codes 41 to 43 have the following common features of the information code 40. FIG. 8 is a diagram showing an example of the information code 40 according to this embodiment. In this embodiment, the information code 40 is a matrix-type two-dimensional code, and an example is shown in which the information code 40 is configured using a color QR code composed of information cells of three or more colors, but the information code 40 is not limited to this configuration and may be a QR code (registered trademark) composed of white and black information cells arranged in a grid pattern.

[0026] As shown in Figure 8, the information code 40 of this embodiment is a rectangular two-dimensional code having an information code area 401 consisting of two or more colored information cells 402 which serve as units for displaying information, a teacher code area 403 having teacher cells 404 which are the same color as the information cells 402 and have the same number of colors as the information cells 402 in order to identify the color of the information cells 402, and an extraction symbol 405.

[0027] In particular, the information code 40 according to this embodiment has multiple teacher cells 404 in the teacher code region 403 to improve the accuracy of identifying the colors of the information cells 402. The color types of the teacher cells 404 and the information cells 402 match, and by comparing the colors of the teacher cells 404 and the information cells 402, it is possible to identify the colors of the information cells 402 with high accuracy. In particular, in a color QR code, the more the color types, the closer the hues of the colors become. Therefore, it may be difficult to properly identify the colors of the information cells 402 depending on the lighting environment, the printing environment of the information code 40, the display environment of the information code 40 on a display, fading of the printed information code 40 over time, and other factors. Even in such cases, the information in the information cells 402 can be properly understood by identifying the colors of the information cells 402 with reference to the teacher cells 404. For example, if the color information of an information cell 402 is purplish and it is difficult to distinguish whether it is similar to red or blue, and the color information is closer to red than the color information of the purple teacher cell 404, it can be determined that the color of the information cell 402 is red. Note that the color information can be quantified as RGB values ​​or CMY values.

[0028] The information code area 401 can record specific information consisting of a certain amount of character information and / or binary information by changing the display pattern of the information cells 402, which are information units. The content of the specific information recorded in the information code area 401 is not particularly limited, but in this embodiment, personal information including biometric authentication information for biometric authentication can be stored. In addition to biometric authentication information, personal information can include information such as a mobile phone number, My Number, passport number, account number, driver's license number, name, social insurance number, date of birth, place of birth, and maiden name. Furthermore, biometric authentication information can include a face image, fingerprint information, iris information, palm shape, retina, blood vessels, voice, ear shape, and the like.

[0029] In the information code 40 according to this embodiment, the information code area 401 in which specific information is recorded is composed of information cells 402 of three or more colors, and can record a larger amount of information than an information code composed of two colors, white and black. However, the data capacity that can be stored in the information code 40 is smaller than that of other recording media, so when recording an image of the entire face with a resolution sufficient for face recognition, even the information code area 401 composed of information cells 402 of four colors may not have enough storage capacity. Therefore, in the information code 40 according to this embodiment, only parts of the face that are characteristic points for face recognition, such as the user's eyes and mouth, are stored as the face image for face recognition, rather than the entire face, so that the face image for face recognition can be recorded in the information code 40.

[0030] Next, an offline monetary transaction process according to the first embodiment will be described. FIGS. 9 and 10 are flowcharts illustrating the offline monetary transaction process according to the first embodiment. In the offline monetary transaction process illustrated in FIGS. 9 and 10, the buyer terminal 20 is assumed to have a sufficient amount of electronic money charged to cover the transaction amount in an environment where network communication such as the Internet is available. In the following description, the seller terminal 10 is assumed to be a mobile terminal with a telephone function, such as a smartphone, and to have a mobile phone number or a product identification number stored in the storage unit 15 as information for identifying the seller terminal 10 itself. Examples of the product identification number for identifying the seller terminal 10 include a MAC address and an IMEI number. While both the mobile phone number and the product identification number can be used as information for identifying the seller terminal 10 itself, one of the seller's mobile phone number and the product identification number of the seller terminal 10 can also be used. In the following description, the seller's mobile phone number is assumed to be used as information for identifying the seller terminal 10.

[0031] In step S101, identity authentication is performed at each of the seller terminal 10 and the buyer terminal 20. For example, in this embodiment, when the seller terminal 10 and the buyer terminal 20 launch an application or app, first, a facial image is read using the cameras 11 and 21, and facial authentication is performed. Note that the facial authentication method is not particularly limited, and any known method can be used. Furthermore, facial information required for facial authentication can be captured in advance using the cameras 11 and 21 and stored in the storage units 15 and 25. Then, in step S102, it is determined whether facial authentication has been performed at each of the seller terminal 10 and the buyer terminal 20. If facial authentication is successful at both the seller terminal 10 and the buyer terminal 20, the process proceeds to step S103. On the other hand, if facial authentication is not successful at either the seller terminal 10 or the buyer terminal 20, the offline monetary transaction process shown in FIG. 9 cannot be continued. Therefore, in step S121, an error message is displayed, and the offline monetary transaction process ends.

[0032] In step S103, data on the transaction amount of the monetary transaction is acquired by seller terminal 10. For example, seller terminal 10 can be configured to display a screen on display 13 prompting the seller to input the transaction amount, to have the seller input the transaction amount via input unit 14, and to acquire data on the transaction amount input by the seller.

[0033] In step S104, the seller terminal 10 generates an information code 41 including the transaction information and the first timestamp, and displays the generated information code 41 on the display 13. Specifically, the seller transaction function of the seller terminal 10 first generates a new transaction code and a first timestamp and stores the generated transaction code in the memory unit 15. The seller transaction function also generates an information code 41 (transaction start image information) that includes, as transaction information, the generated transaction code, the seller code and the seller's mobile phone number stored in the memory unit 15, and the transaction amount data acquired in step S103, and that also includes, as second security information, the first timestamp indicating the time when the transaction started. The seller transaction function then displays the generated information code 41 on the display 13, as shown in FIG. 4.

[0034] In this embodiment, a color QR code is generated and displayed as the information code 41 as shown in Fig. 8, but any known method can be used to generate the color QR code. Preferably, the transaction code is unique at least within the seller terminal 10, and a completely unique code can be created by combining the transaction code with the seller code, the seller's mobile phone number, or the product identification number of the seller terminal 10.

[0035] In step S105, the buyer terminal 20 reads the information code 41 displayed on the seller terminal 10 in step S104. Specifically, the buyer transaction function of the buyer terminal 20 activates the camera 21 and prompts the buyer to read the information code 41 displayed on the seller terminal 10. When the buyer then captures an image of the information code 41 displayed on the seller terminal 10 with the camera 21, the buyer transaction function obtains, from the image data of the read information code 41, transaction information such as the seller code, transaction code, transaction amount, and seller's mobile phone number, as well as information on the first timestamp, as second security information.

[0036] In step S106, the purchaser-side transaction function of the purchaser-side terminal 20 approves the payment. For example, in step S103, the purchaser-side transaction function reads out transaction information from the information code 41, and displays on the display 23 a screen showing the transaction amount included in the read out transaction information, the terminal balance data stored in the purchaser-side terminal 20, the balance after payment, and other information, as well as a payment button, as shown in FIG. 6(A). When the purchaser presses the payment button displayed on the display 23, the purchaser-side transaction function displays on the screen a message requesting approval of the payment, as shown in FIG. 6(B). In response, if the purchaser gives an instruction to approve the payment via the input unit 24, the purchaser-side transaction function approves the payment at the purchaser-side terminal 20.

[0037] In step S107, the buyer-side transaction function of the buyer-side terminal 20 determines whether the expiration date of the information code 41 has passed. Specifically, the buyer-side transaction function determines whether a predetermined time (expiration date) has passed since the first timestamp, based on the first timestamp included in the information code 41 read in step S105. If the expiration date has passed, to ensure safety, the process proceeds to step S121, where an error message is displayed and the offline monetary transaction process ends. On the other hand, if the predetermined time (expiration date) has not passed since the first timestamp, the process proceeds to step S108.

[0038] In step S108, because the payment has been approved and is within the expiration date based on the first timestamp, the purchaser transaction function of the purchaser terminal 20 deducts the electronic money balance data. For example, as shown in Figures 6(A) and 6(B), if the electronic money terminal balance data is 10,000 yen and the price (transaction amount) is 2,800 yen, the purchaser transaction function deducts 2,800 yen from the electronic money terminal balance data of 10,000 yen and updates the terminal balance data to 7,200 yen.

[0039] In step S109, the buyer-side transaction function of the buyer-side terminal 20 displays an information code 42 (payment completion image information) indicating payment completion on the display 23. Specifically, the buyer-side transaction function generates the information code 42 including authentication information such as the seller code, the transaction code, the transaction amount, and the seller's mobile phone number, payment completion information indicating payment completion, and a second timestamp, which is the first security information, and displays the generated information code 42 as payment completion image information indicating payment completion on the display 23, as shown in Fig. 7. Also, in the following step S110, the seller-side transaction function of the seller terminal 10 reads the information code 42 indicating payment completion that was displayed on the display 23 of the buyer-side terminal 20 in step S109, as shown in Fig. 10.

[0040] If it is determined in step S107 that the expiration date based on the first timestamp has passed, the purchaser terminal 20 can automatically or manually update the information code 42 to display the information code 42 again. When the information code 42 is updated, the timestamp is updated, but the seller code, transaction code, transaction amount, and seller's mobile phone number remain unchanged and are included in the information code 42.

[0041] In step S111, the seller transaction function of the seller terminal 10 compares the mobile phone numbers. Specifically, the seller transaction function determines whether the seller's mobile phone number stored in the memory unit 15 of the seller terminal 10 matches the seller's mobile phone number included in the information code 42 read in step S110.

[0042] In step S112, the seller's transaction function compares the transaction codes. Specifically, the seller's transaction function determines whether a valid transaction code (a transaction code that has not been deleted in step S116, which will be described later; hereinafter, also referred to as a valid transaction code) stored in the memory unit 15 of the seller terminal 10 matches the transaction code included in the information code 42 read in step S110.

[0043] Then, in step S113, the seller's transaction function determines whether both the mobile phone number and the transaction code match. If either the mobile phone number or the transaction code does not match, it is assumed that there is a possibility of an error or fraud by a third party (details will be described later), and the process proceeds to step S121, where the seller's transaction function displays an error message indicating that the transaction cannot be completed, and the offline monetary transaction process ends. On the other hand, if both the mobile phone number and the transaction code match, the process proceeds to step S114.

[0044] In step S114, the seller transaction function of the seller terminal 10 determines whether the expiration date of the information code 42 has passed. Specifically, the seller transaction function determines whether a predetermined time (expiration date) has passed since the second timestamp, based on the second timestamp included in the information code 42 read in step S110. If the expiration date has passed, the process proceeds to step S118. On the other hand, if the predetermined time (expiration date) has not passed since the second timestamp, the process proceeds to step S115.

[0045] In step S115, because both the mobile phone number and the transaction code match and the expiration date based on the second timestamp is within the period, the seller transaction function of the seller terminal 10 increments the terminal balance data of the seller terminal 10 based on the information code 42 indicating payment completion read in step S110. Specifically, the seller transaction function confirms that payment has been completed at the buyer terminal 20 based on the payment completion information included in the information code 42, and increments the terminal balance data of the electronic money of the seller terminal 10 by the amount of the transaction.

[0046] In the following step S116, the seller terminal 10 deletes the transaction code stored in the memory unit 15. Then, in step S117, the seller terminal 10 turns off (e.g., grays out) the display (a button such as an icon) for reading the information code 42 on the buyer terminal 20. In this manner, in this embodiment, when the seller terminal 10 completes the increase in the terminal balance data, the transaction code is deleted from the seller terminal 10 and made unreadable. This allows the same seller terminal 10 to read the information code 42 displayed on the buyer terminal 20 again, preventing the terminal balance data from being increased more than once for the same transaction. Even if step S117 is not performed and the information code 42 remains readable at the seller terminal 10, if the transaction code is deleted at step S116, when the information code 42 displayed at the buyer terminal 20 is read again (step S109), it will be determined at step 112 that the transaction codes do not match, making it impossible to increase the terminal balance data again at the seller terminal 10. Furthermore, in this embodiment, even if the expiration date based on the second timestamp has passed, it is impossible to increase the terminal balance data again, enabling more secure transactions.

[0047] In this way, by determining in step S113 whether the transaction code and the mobile phone number match, it is possible to prevent fraudulent increases in the terminal balance data when another mobile terminal unrelated to the transaction (a mobile terminal that did not display information code 41 in step S104, hereinafter referred to as an unrelated terminal) reads information code 42 displayed on buyer terminal 20. In other words, an unrelated terminal other than seller terminal 10 that presented information code 41 does not generate a transaction code for the current transaction in step S104, and is unable to transmit the mobile phone number of the unrelated terminal to buyer terminal 20. Therefore, in step S113, the transaction code and mobile phone number contained in information code 42 displayed on buyer terminal 20 cannot be matched, and an error message such as "This is a different transaction. Please confirm the transaction item and the purchaser and photograph the information code again" is displayed in step S121.

[0048] Also, if the expiration date of the information code 42 has passed in step S114, the process proceeds to step S118. In step S118, the seller transaction function of the seller terminal 10 generates a cancellation information code 43 at the seller terminal 10 without increasing the terminal balance data of the seller terminal 10, and the cancellation information code 43 is displayed on the display 13. Here, the cancellation information code 43 is an information code for canceling the deduction of the terminal balance data stored in the memory unit 25 of the buyer terminal 20, and includes cancellation instruction information. When step S114 is executed, the buyer terminal 20 has already performed the process of deducting the terminal balance data stored in the memory unit 25 (step S108). Therefore, in order to cancel the transaction, it is necessary to cancel the deduction of the terminal balance data of the buyer terminal 20. In this embodiment, the cancellation instruction included in the cancellation information code 43 is used as a trigger to execute the process of canceling the deduction of the terminal balance data of the buyer terminal 20.

[0049] In step S119, the buyer terminal 20 reads the cancellation information code 43 displayed on the seller terminal 10 in step S118. Then, in step S120, the buyer transaction function of the buyer terminal 20 cancels the deduction from the terminal balance data of the buyer terminal 20, triggered by the information code 43 read in step S119. This returns the terminal balance data of the buyer terminal 20 to the state before the transaction. Then, the process proceeds to step S121, where a message is displayed indicating that the balance data of the buyer terminal 20 has been deducted and that the monetary transaction was not completed successfully.

[0050] 9 and 10 is performed as described above. Note that when the offline monetary transaction process is completed, the terminal balance data of the seller terminal 10 and the server balance data of the seller terminal 10 stored in the server 30 will no longer match. Therefore, when a network communication environment is established after the offline monetary transaction process, the data update function of the seller terminal 10 accesses the server 30 and updates the server balance data stored in the server 30 so that it matches the terminal balance data stored in the seller terminal 10.

[0051] 9 and 10 illustrate an example in which an offline monetary transaction is initiated by a seller entering a transaction amount into seller terminal 10, but the present invention is not limited to this configuration. For example, an offline monetary transaction can be initiated by a buyer entering a transaction amount into buyer terminal 20. For example, a QR code containing the seller's identification information can be placed in a store, and the buyer can read the QR code using buyer terminal 20 and then enter the transaction amount, thereby completing step S105 of the offline monetary transaction processing described above. In this case, since the QR code placed in the store does not include a first timestamp, the buyer terminal 20 can also be configured to obtain the time when the QR code is read as the first timestamp.

[0052] As described above, in the first embodiment, the first timestamp and the second timestamp are used to determine whether the expiration date of the information code has passed, and if the expiration date of the information code 41 indicating the start of the transaction has passed, the deduction of the balance data at the buyer's terminal 20 is prohibited, and if the expiration date of the information code 42 indicating the completion of payment has passed, the deduction of the balance data at the seller's terminal 10 is prohibited, and the deduction of the balance data executed at the buyer's terminal is canceled, thereby increasing the security of the transaction.

[0053] Second Embodiment Next, a second embodiment of the present invention will be described. The monetary transaction system 1 according to the second embodiment is a system for securely conducting offline monetary transactions by using an information code 41 containing the public key of the merchant terminal 10 (hereinafter also referred to as the merchant's public key) as second security information and an information code 42 containing payment completion information encrypted with the public key as first security information, thereby permitting only authorized merchants (merchants who have provided the public key) to conduct monetary transactions. The monetary transaction system 1 according to the second embodiment has the same configuration as the monetary transaction system 1 according to the first embodiment, and operates in the same manner as the monetary transaction system 1 according to the first embodiment, except for the operation described below.

[0054] In the second embodiment, the seller terminal 10 generates a public key and a private key in advance and stores them in the storage unit 15. The seller transaction function of the seller terminal 10 displays an information code 41 containing the public key on the display 13, causing the buyer terminal 20 to capture an image showing the information code 41 and acquire the seller's public key. The seller transaction function decrypts payment completion information encrypted by the buyer terminal 20 using the seller's public key using the seller's private key, confirms the payment completion information, and thereby increases the balance data. This prevents anyone other than the legitimate seller (the seller who provided the public key) from posing as the seller to acquire payment completion information and fraudulently increase the balance data. In this embodiment, the encryption process using the public key and the decryption process using the private key can be performed using known methods.

[0055] Furthermore, in the second embodiment, the purchaser terminal 20 can capture and read an image showing the information code 41 including the seller's public key, thereby obtaining the seller's public key from the read information code 41. Furthermore, when the purchaser terminal 20 reduces the balance data according to the transaction amount, it can encrypt payment completion information indicating the completion of payment using the obtained public key.

[0056] 11 and 12 are flowcharts showing offline monetary transaction processing according to the second embodiment. The offline monetary transaction processing according to the second embodiment will be described below with reference to FIGS.

[0057] In steps S201 to S203, similar to steps S101 to S103 in the first embodiment, personal authentication is performed at each of the seller terminal 10 and the buyer terminal 20, and it is determined whether or not facial authentication has been successful. If facial authentication is successful at both the seller terminal 10 and the buyer terminal 20, the process proceeds to step S203, where data on the transaction amount of the monetary transaction is acquired by the seller terminal 10. On the other hand, if facial authentication has not been successful, the process proceeds to step S216, where an error message is displayed, and the offline monetary transaction process ends.

[0058] In step S204, the seller terminal 10 generates an information code 41 (transaction start image information) including the seller's public key, which is the second security information, and the transaction information, and displays the generated information code 41 on the display 13. Specifically, the seller transaction function of the seller terminal 10 first generates an information code 41 including the transaction amount data acquired in step S203 as the transaction information and the seller's public key stored in the memory unit 15 as the second security information. Then, the seller transaction function displays the generated information code 41 on the display 13, as shown in FIG.

[0059] In step S205, the buyer terminal 20 reads the information code 41 displayed on the seller terminal 10 in step S204. As a result, the buyer transaction function obtains the sales amount data, which is transaction information, and the seller's public key, which is second security information, from the image data of the read information code 41.

[0060] In steps S206 and S207, similar to steps S106 and S108 in the first embodiment, the payment is approved by the buyer-side transaction function of the buyer-side terminal 20, and as a result, the electronic money balance data is deducted by the buyer-side transaction function of the buyer-side terminal 20.

[0061] In step S208, the buyer-side transaction function of the buyer terminal 20 encrypts information indicating payment completion with the seller's public key. Specifically, the buyer-side transaction function encrypts payment completion information indicating that payment of the transaction amount has been completed at the buyer terminal 20 with the seller's public key acquired in step S205. In step S209, the buyer-side transaction function displays on the display 23 an information code 42 containing the payment completion information encrypted in step S208 as first security information. Specifically, the buyer-side transaction function generates an information code 42 containing the encrypted payment completion information and displays the generated information code 42 on the display 23, as shown in FIG. 7. In the following step S210, the seller-side transaction function of the seller terminal 10 reads the information code 42 indicating payment completion that was displayed on the display 23 of the buyer terminal 20 in step S209.

[0062] In step S211, the seller transaction function of the seller terminal 10 decrypts the encrypted payment completion information acquired in step S210. Specifically, the seller terminal 10 stores the seller's private key in the storage unit 15, and can use this private key to decrypt the payment completion information encrypted in step S208. Then, in step S212, the seller transaction function determines whether payment completion has been confirmed. Here, the payment completion information included in the information code 42 is encrypted with the seller's public key. The seller's seller terminal 10 can decrypt the encrypted payment completion information using the private key, thereby confirming payment completion. On the other hand, if, for example, a person other than the seller secretly photographs the information code 42 displayed by the buyer terminal 20 using that person's terminal in order to increase the balance data, the encrypted payment completion information cannot be decrypted, and payment completion cannot be confirmed. Therefore, the process proceeds to step S216, where an error message is displayed.

[0063] In steps S213 to S215, similar to steps S115 to S117 in the first embodiment, the seller-side transaction function of the seller terminal 10 increases the terminal balance data of the seller terminal 10, and the display (button such as an icon) for reading the information code 42 of the buyer terminal 20 is turned off (for example, grayed out), after which the offline monetary transaction processing in the second embodiment ends.

[0064] 11 and 12 also illustrate a configuration in which an offline monetary transaction is initiated by the seller entering the transaction amount into seller terminal 10, but the configuration is not limited to this. For example, a QR code containing the seller's identification information may be placed in the store, and the buyer may read the QR code using buyer terminal 20 and then enter the transaction amount. In this case, the seller's public key may be included in the QR code placed in the store as the seller's identification information, and the process proceeds to step S205.

[0065] As described above, in the second embodiment, the buyer terminal 20 encrypts the payment completion information with the seller's public key generated by the seller terminal 10, and the seller terminal 10 decrypts the payment completion information encrypted by the buyer terminal 20 with the seller's private key, thereby confirming whether the buyer has completed the payment and increasing the seller's balance data. As a result, in the second embodiment, only the legitimate seller who possesses the private key corresponding to the public key can confirm the buyer's payment. Therefore, even if a malicious third party steals the information code 42 containing the payment completion information displayed by the buyer terminal 20, the third party's terminal cannot decrypt the payment completion information encrypted with the seller's public key, so the payment completion information cannot be confirmed and the seller's balance data cannot be unfairly increased, thereby ensuring the security of heartstring transactions.

[0066] Although the preferred embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the above-described embodiments. Various modifications and improvements can be made to the above-described embodiments, and such modifications and improvements are also included in the technical scope of the present invention.

[0067] For example, in the above-described embodiment, from the viewpoint of privacy protection, seller terminal 10 and buyer terminal 20 may be configured not to exchange data that could identify seller terminal 10 and buyer terminal 20. For example, seller terminal 10 and buyer terminal 20 may display information codes 41 and 42 containing only data on the transaction code and transaction amount as transaction information, thereby preventing the system from tracking information such as who the transaction was with and what the transaction was, just as in monetary transactions using only actual currency.

[0068] In addition, in the above-described embodiment, electronic money was used as an example of monetary data used by the seller terminal 10 and the buyer terminal 20, but this configuration is not limited to this, and it is also possible to use, for example, digital currency, points, virtual currency, etc. as monetary data.

[0069] In addition, in the above-described embodiment, as shown in FIG. 8, the information code 40 has been configured such that the teacher code area 403 is located on the lower left side of the information code area 401. However, the location of the teacher code area 403 is not particularly limited, and the teacher code area 403 may be located, for example, above or below the information code area 401. In the example shown in FIG. 8, the teacher code area 403 is located adjacent to the information code area 401, but it may also be located away from the information code area 401. Furthermore, in the example shown in FIG. 8, the information code 40 has only one teacher code area 403. However, this is not limited to this configuration, and the information code 40 may have multiple teacher code areas 403, such as one teacher code area 403 located above and one teacher code area 403 located below the information code area 401. In addition, the information code 40 may have one or more teacher code areas 403 located inside the information code area 401. [Explanation of symbols]

[0070] 1. Monetary transaction system 10...Seller terminal 11...Camera 12. Communications Department 13...Display 14...Input section 15...Storage section 16...Arithmetic section 20...Purchaser's terminal 21...Camera 22…Communications Department 23...Display 24...Input section 25...Storage section 26...Arithmetic section 30...Server 40~42...Information code 401...Information code area 402...Information cell 403...Teacher code area 404...Teacher cell 405...Cut-out symbol 2. Internet connection

Claims

1. A monetary transaction system comprising: a first information terminal having a first image display unit and a first image reading unit; and a second information terminal having a second image display unit and a second image reading unit, wherein monetary transactions based on monetary data are executed offline between the first information terminal and the second information terminal, The first information terminal a first storage means for storing balance data held by the first information terminal; a first acquisition means for acquiring data on the transaction amount of the monetary transaction; a payment means for deducting the balance of the balance data stored in the first storage means in accordance with the transaction amount data acquired by the first acquisition means; a first display means for displaying, on the first image display unit, first security information or payment completion image information including information based on the first security information when the deduction of the balance in the balance data by the payment means is completed; The second information terminal a second storage means for storing balance data held by the second information terminal; a second image reading means for causing the second image reading unit to read the payment completion image information displayed by the first information terminal; a second acquiring means for acquiring the first security information or information based on the first security information from the payment completion image information; a receiving means for increasing the balance of the balance data stored in the second storage means in accordance with the transaction amount when the payment completion image information is read, The receiving means determines whether to increase the balance in the balance data based on the first security information.

2. the second information terminal has second display means for displaying image information for canceling a transaction on the second image display unit when the receiving means is prohibited from increasing the balance of the balance data based on the first security information, The first information terminal a first image reading means for causing the first image reading unit to read the transaction cancellation image information displayed by the second information terminal; 2. The monetary transaction system according to claim 1, further comprising a cancellation means for canceling a deduction made by said payment means to the balance of the balance data stored in said first storage means when said transaction cancellation image information is read.

3. the first security information is information indicating an expiration date of the payment completion image information, The monetary transaction system described in claim 1, wherein in the second information terminal, the receiving means determines whether the expiration date of the payment completion image information has passed based on the first security information, and if the expiration date of the payment completion image information has passed, prohibits an increase in the balance of the balance data stored in the second storage means.

4. the information based on the first security information is payment completion information encrypted with the public key of the second information terminal, In the second information terminal, the second storage means stores a private key corresponding to the public key; 2. The monetary transaction system of claim 1, wherein the receiving means decrypts payment completion information encrypted with the public key with the private key, and when it confirms that payment has been completed at the first information terminal based on the decrypted payment completion information, it allows an increase in the balance of the balance data stored in the second storage means.

5. The second information terminal an input means for inputting the transaction amount; a second display means for generating transaction start image information including transaction information including the transaction amount input by the input means and second security information, and displaying the transaction start image information on the second image display unit of the second information terminal; the first information terminal has a first image reading means for causing the first image reading unit to read the transaction start image information displayed on the second image display unit of the second information terminal; 2. The monetary transaction system according to claim 1, wherein in the first information terminal, the first acquisition means acquires the transaction information and the second security information from the transaction start image information.

6. the second security information is information indicating an expiration date of the transaction start image information, The monetary transaction system described in claim 5, wherein in the first information terminal, the payment means determines whether the expiration date of the transaction start image information has passed based on the second security information, and if the expiration date of the transaction start image information has passed, prohibits the reduction of the balance of the balance data stored in the first storage means.

7. the second security information is a public key of the merchant; The monetary transaction system described in claim 5, wherein in the first information terminal, when the payment means has completed reducing the balance of the balance data, the first display means encrypts payment completion information based on the second security information, thereby converting the encrypted payment completion information into information based on the first security information, and displays payment completion image information including the encrypted payment completion information on the first image display unit.

8. 2. The monetary transaction system according to claim 1, wherein the payment completion image information is displayed as an information code having information cells arranged two-dimensionally as information units.

9. A financial transaction system includes a first information terminal having a first image display unit and a first image reading unit, and a second information terminal having a second image display unit and a second image reading unit, and executes financial transactions based on financial data between the first information terminal and the second information terminal offline, the system comprising: a computer program executed by the first information terminal, a first storage function for storing balance data held by the first information terminal; a first acquisition function for acquiring data on the transaction amount of the monetary transaction; a payment function of deducting the balance of the stored balance data in accordance with the transaction amount when the user of the first information terminal approves the payment of the transaction amount; A computer program that executes a display function that displays first security information or payment completion image information including information based on the first security information on the first image display unit when the balance reduction of the balance data by the payment function is completed.

10. A financial transaction system includes a first information terminal having a first image display unit and a first image reading unit, and a second information terminal having a second image display unit and a second image reading unit, and executes financial transactions based on financial data between the first information terminal and the second information terminal offline, the system comprising: a computer program executed by the second information terminal, a second storage function for storing balance data held by the second information terminal; a second image reading function that, when payment completion image information indicating that payment has been completed is displayed on the first information terminal, causes the second image reading unit to read the payment completion image information displayed on the first information terminal; a second acquisition function for acquiring first security information or information based on the first security information from the payment completion image information; a receiving function of increasing the balance of the balance data stored in the second information terminal in accordance with the transaction amount when the payment completion image information is read; The receiving function determines whether to increase the balance of the balance data based on the first security information.

11. A monetary transaction method for executing a monetary transaction offline based on monetary data between a first information terminal having a first image display unit and a first image reading unit, and a second information terminal having a second image display unit and a second image reading unit, the method comprising: the first information terminal stores balance data held by the first information terminal, acquires data on the transaction amount for the monetary transaction, and when the user of the first information terminal approves payment of the transaction amount, reduces the balance of the balance data held by the first information terminal according to the transaction amount, and when the reduction of the balance of the balance data is completed, displays first security information or payment completion image information including information based on the first security information on the first image display unit; An offline monetary transaction method in which the second information terminal stores balance data held by the second information terminal, and when the second image reading unit reads the payment completion image information displayed by the first information terminal, determines based on the first security information whether to increase the balance of the balance data stored in the second information terminal, and if it determines to increase the balance data, increases the balance data according to the transaction amount.

Images