Money transaction system, information terminal, computer program, and money transaction method

Abstract

To provide a money transaction system, a computer program, and a money transaction method capable of safely carrying out money transactions even offline. [Solution] The first information terminal 20 has an encryption means 26 that encrypts transaction information including transaction amount data with the private key of the first information terminal 20, a monetary processing means 26 that increases or decreases the first balance data based on the transaction amount data, and a first display means 26 that displays image information including the encrypted transaction information and the public key of the first information terminal 20, and the second information terminal 10 has a second image reading means 16 that reads the image information displayed by the first information terminal 20, a second acquisition means 16 that acquires the encrypted transaction information and the public key of the first information terminal 20 from the image information, a decryption means 16 that decrypts the encrypted transaction information using the public key of the first information terminal 20, and a monetary processing means 16 that increases or decreases the first balance data based on the transaction amount data included in the decrypted transaction information.

Description

[Technical field]

[0001] The present invention relates to a monetary transaction system, an information terminal, 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 when offline. [Background technology]

[0002] Conventionally, a monetary transaction system has been disclosed in which an information terminal such as a smartphone carried by a purchaser and an information terminal held by a seller can both be connected to a monetary transaction server via a network, and the purchaser's information terminal and the seller's information terminal each access the server, 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). However, the monetary transaction system of Patent Document 1 executes monetary transactions between two information terminals in an environment where network communication is possible via a server, and cannot perform monetary transactions in an offline environment. Therefore, the applicant has proposed a technology (hereinafter, referred to as an offline monetary transaction system) that enables monetary transactions based on monetary data to be carried out between two information terminals by using an information code even in an offline environment (for example, Patent Document 2). In such offline monetary transaction systems, as in online monetary transaction systems, monetary data is exchanged and security needs to be strengthened. The applicant has filed a patent application for technology that strengthens the security of monetary transactions by comparing the identification information of the two information terminals that carry out monetary transactions and using time stamps, so that a third party not involved in the monetary transaction cannot steal the information code and unjustly seize the monetary data. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-062125 A [Patent Document 2] Patent No. 7486756 Summary of the Invention [Problem to be solved by the invention]

[0004] Security measures in offline monetary transaction systems include measures to prevent a malicious third party from stealing transaction data and obtaining illegal benefits, as well as measures to prevent a malicious transactor (buyer or seller) from falsifying transaction data and obtaining illegal benefits. However, no measures against falsifying transaction data have been proposed in the past for offline monetary transaction systems.

[0005] The present invention aims to provide a monetary transaction system, information terminal, 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 present invention relates to a monetary transaction system as set forth in (1) or (2) below. (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, and which 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 first balance data held by the first information terminal and a private key and a public key of the first information terminal, a first acquisition means for acquiring transaction amount data in the monetary transaction, an encryption means for encrypting transaction information including the transaction amount data acquired by the first acquisition means with the private key of the first information terminal, and a monetary transaction processing means for increasing or decreasing the first balance data based on the transaction amount data acquired by the first acquisition means. and a first display means for displaying image information including the encrypted transaction information and the public key of the first information terminal on the first image display unit, wherein the second information terminal has: second storage means for storing second balance data held by the second information terminal; second image reading means for causing the second image reading unit to read the image information displayed by the first information terminal; second acquisition means for acquiring the encrypted transaction information and the public key of the first information terminal from the image information; decryption means for decrypting the encrypted transaction information using the public key of the first information terminal; and money processing means for increasing or decreasing the second balance data based on transaction amount data included in the transaction information decrypted by the decryption means. (2) The monetary transaction system according to (1) above, wherein the second information terminal stores the transaction information in an encrypted state. (3) The second information terminal stores a private key and a public key of the second information terminal in the second storage means, and the second information terminal further has a second encryption means for encrypting the transaction information acquired from the first information terminal with the private key of the second information terminal, and a second display means for displaying image information including the transaction information encrypted by the second encryption means and the public key of the second information terminal on the second image display unit. The monetary transaction system described in (1) above. The present invention also provides an information terminal as described in (4) below. (4) In a monetary transaction system for offline execution of monetary transactions based on monetary data between a first information terminal and a second information terminal, the first information terminal comprises: a first storage means for storing first balance data held by the first information terminal and a private key and a public key of the first information terminal; a first acquisition means for acquiring transaction amount data in the monetary transaction; an encryption means for encrypting transaction information including the transaction amount data acquired by the first acquisition means with the private key of the first information terminal; a monetary processing means for increasing or decreasing the first balance data based on the transaction amount data acquired by the first acquisition means; and a first display means for displaying image information including the encrypted transaction information and the public key of the first information terminal; The image information displayed by the first display means is read by the second information terminal, and the balance data of the second information terminal is increased or decreased at the second information terminal based on the encrypted transaction information included in the image information and the public key of the first information terminal. Information terminal. Furthermore, the present invention relates to an information terminal as set forth in (5) or (6) below. (5) A second information terminal in a monetary transaction system that executes monetary transactions based on monetary data between a first information terminal and a second information terminal offline, wherein the first information terminal has a means for displaying image information including transaction information including transaction amount data encrypted with a private key of the first information terminal and a public key of the first information terminal for decrypting the encrypted transaction information, and the second information terminal has a second storage means for storing second balance data held by the second information terminal, a second image reading means for reading the image information displayed by the first information terminal, a second acquisition means for acquiring the encrypted transaction information and the public key of the first information terminal from the image information, a decryption means for decrypting the encrypted transaction information using the public key of the first information terminal, and a monetary processing means for increasing or decreasing the first balance data based on the transaction amount data included in the transaction information decrypted by the decryption means. (6) The information terminal according to (5) above, which stores the transaction information in an encrypted state. In addition, the present invention relates to a server as described in (7) below. (7) A server capable of communicating with the information terminal described in (4) above and the information terminal described in (5) or (6) above, The first information terminal has 1Balance data and / or The second information terminal has A server comprising: a server memory unit that stores second balance data as server balance data; and an update unit that acquires the first balance data and / or the second balance data from the first information terminal or the second information terminal as terminal balance data, acquires the transaction information, and updates the server balance data stored in the server memory unit based on the acquired terminal balance data and the transaction information. In addition, the present invention relates to a computer program according to any one of (8) to (10) below. (8) In a monetary 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 a monetary transaction based on monetary data between the first information terminal and the second information terminal offline, a computer program executed by the first information terminal has a function of storing first balance data held by the first information terminal and a private key and a public key of the first information terminal, a function of acquiring transaction amount data in the monetary transaction, a function of encrypting transaction information including the acquired transaction amount data with the private key of the first information terminal, a function of increasing or decreasing the first balance data based on the acquired transaction amount data, and a function of displaying image information including the encrypted transaction information and the public key of the first information terminal. The image information displayed by the display function is read by the second information terminal, and the balance data of the second information terminal is increased or decreased at the second information terminal based on the encrypted transaction information included in the image information and the public key of the first information terminal. Computer program. (9) In a monetary 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 monetary transactions based on monetary data between the first information terminal and the second information terminal offline, a computer program executed by the second information terminal, wherein the first information terminal has a means for displaying image information including transaction information including transaction amount data encrypted with a private key of the first information terminal and a public key of the first information terminal, and the computer program of the second information terminal has a function of storing second balance data held by the second information terminal, a function of causing the second image reading unit to read the image information displayed by the first information terminal, a function of obtaining the encrypted transaction information and the public key of the first information terminal from the image information, a function of decrypting the encrypted transaction information using the public key of the first information terminal, and a function of increasing or decreasing the second balance data based on the transaction amount data included in the decrypted transaction information. (10) The computer program according to (9) above, further having a function of storing the transaction information in an encrypted state. The present invention also provides a monetary transaction method as set forth in (11) or (12) below. (11) A monetary transaction method executed by a first information terminal when performing a monetary transaction based on monetary data between a first information terminal and a second information terminal offline using 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 including storing first balance data held by the first information terminal and a private key and a public key of the first information terminal, acquiring data on a transaction amount in the monetary transaction, encrypting transaction information including the acquired transaction amount data with the private key of the first information terminal, increasing or decreasing the first balance data based on the acquired transaction amount data, and displaying image information including the encrypted transaction information and the public key of the first information terminal. the image information displayed by the first information terminal is read by the second information terminal, and the balance data of the second information terminal is increased or decreased in the second information terminal based on the encrypted transaction information included in the image information and the public key of the first information terminal. . (12) A monetary transaction method executed by a second information terminal when performing a monetary transaction based on monetary data between a first information terminal and a second information terminal offline using 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 first information terminal having a means for displaying image information including transaction information including data of a transaction amount encrypted with a private key of the first information terminal and a public key of the first information terminal, the second information terminal storing second balance data held by the second information terminal, reading the image information displayed by the first information terminal using the second image reading unit, obtaining the encrypted transaction information and the public key of the first information terminal from the image information, decrypting the encrypted transaction information using the public key of the first information terminal, and increasing or decreasing the second balance data based on the transaction amount data included in the decrypted transaction information. Financial transaction methods . Effect 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 executed between two information terminals. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing a configuration of a monetary transaction system according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a diagram for explaining a usage scene of a monetary transaction system according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a block diagram of a seller terminal and a buyer terminal according to the embodiment of the present invention. [Figure 4] FIG. 2 is a diagram for explaining an information code according to the embodiment; [Diagram 5] 10 is a diagram for explaining information contained in an information code stored in a storage unit. FIG. [Figure 6] FIG. 13 is a diagram showing a transaction screen displayed on a seller terminal. [Figure 7]FIG. 13 is a diagram showing a charge screen displayed on a purchaser terminal. [Figure 8] FIG. 13 is a diagram showing a payment screen displayed on a purchaser terminal. [Figure 9] FIG. 13 shows a payment completion screen displayed on the purchaser terminal. [Figure 10] 1 is a flowchart (part 1) showing an offline monetary transaction process according to the present embodiment. [Figure 11] 13 is a flowchart (part 2) showing the offline monetary transaction process according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 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 the present embodiment, and FIG. 2 is a diagram for explaining a usage scene of the monetary transaction system 1 according to the present embodiment. As shown in FIGS. 1 and 2, the monetary transaction system 1 according to the present embodiment has information terminals 10 and 20 carried by two parties who conduct 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 information terminals 10 and 20 and the server 30 can exchange information with each other by wireless communication or wired communication. On the other hand, in the present 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 information terminals 10 and 20.

[0010] In this embodiment, a purchaser purchases a product from a seller, and a monetary transaction resulting from the purchase of the product is carried out at the information terminal 10 (the 1 information terminal) and the purchaser's information terminal 20 (corresponding to the present invention) 2The following describes an example of a scene in which electronic money is exchanged between a seller and a buyer (corresponding to an information terminal). Here, the information terminal 10 carried by the seller is also referred to as the seller terminal 10, and the information terminal 20 carried by the buyer is also referred to as the buyer terminal 20. However, the monetary transaction system 1 according to the present embodiment is not only used when purchasing goods, but can also be used for splitting the bill for eating and drinking, settling the bill among members of a group travel, collecting a lump sum for a donation, sending money to a family, paying a gift, etc. In addition, the example shown in FIG. 1 and FIG. 2 illustrates a one-to-one situation between a seller who receives electronic money and a buyer who pays electronic money, but the present invention is not limited to this configuration. For example, a configuration in which one person (e.g., a person in charge of a meal payment) receives electronic money from multiple people (e.g., multiple participants in a meal payment) can also be used.

[0011] FIG. 3 is a block diagram showing the configuration 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, and as shown in FIG. 3, has a camera 11, a communication unit 12, a display 13, an input unit 14, a storage unit 15, and a calculation unit 16. The camera 11 performs operations such as reading an information code displayed on the buyer terminal 20. The communication unit 12 communicates with a server 30 in an environment where network communication is available. The display 13 displays an information code 40 including transaction information of a monetary transaction such as a transaction amount on a screen. The input unit 14 is used by the seller to input transaction information such as the transaction amount. It is possible to use a configuration in which the display 13 and the input unit 14 are integrated into a touch display.

[0012] Here, the information code 40 according to this embodiment will be described. Fig. 4 is a diagram showing an example of the information code 40 according to this embodiment. In this embodiment, the information code 40 is a two-dimensional matrix code, and a configuration using a color QR code composed of information cells of three or more colors is illustrated as an example, 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.

[0013] As shown in FIG. 4, 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 are 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.

[0014] In particular, the information code 40 according to this embodiment has a plurality of teacher cells 404 in the teacher code area 403 in order to improve the accuracy of identifying the color of the information cell 402. The color type of the teacher cell 404 and the color type of the information cell 402 are the same, and by comparing the color of the teacher cell 404 with the color of the information cell 402, it is possible to identify the color of the information cell 402 with high accuracy. In particular, in a color QR code, the more the types of colors increase, the closer the hues of each color become. Therefore, it may be difficult to properly identify the color of the information cell 402 depending on the light environment such as lighting, the printing environment of the information code 40, the display environment of the information code 40 on a display or the like, and fading of the printed information code 40 due to aging. Even in such a case, the information of the information cell 402 can be properly grasped by identifying the color of the information cell 402 with reference to the teacher cell 404. For example, if the color information of the information cell 402 is purple 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.

[0015] 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 cell 402, which is an information unit. The content of the specific information recorded in the information code area 401 is not particularly limited, but in this embodiment, the specific information includes transaction information required for monetary transactions between a seller and a buyer, such as identification information of the seller terminal 10 (hereinafter also referred to as the seller terminal PID), identification information of the buyer terminal 20 (hereinafter also referred to as the buyer terminal PID), product name, transaction amount, quantity, subject of transaction, and transaction date and time. The seller terminal PID is identification information such as a seller code for identifying the seller, the seller's mobile phone number, and the product identification number (MAC address or IMEI number) of the seller terminal 10, and similarly, the buyer terminal PID is identification information such as a buyer code for identifying the buyer, the buyer's mobile phone number, and the product identification number (MAC address or IMEI number) of the buyer terminal 20. In addition to the above information, information such as a transaction code (for example, a unique number such as an epoch second or a sequential number under a certain management) and a time stamp can be included as transaction information.

[0016] In this embodiment, the information code 40 includes, in accordance with the timing of presenting the information code 40 as described below, any one of information indicating the start of a transaction, information indicating that a monetary payment has been completed, information indicating that the money has been received, and information indicating that the monetary transaction is to be cancelled. In the following, an information code including information indicating the start of a transaction is referred to as a transaction start information code 41, an information code including information indicating that a monetary payment has been completed is referred to as a payment completion information code 42, an information code including information indicating that the money has been received is referred to as a receipt information code 43, and an information code including information indicating that the monetary transaction is to be cancelled is referred to as a cancellation information code 44, and these information codes 41 to 44 are collectively referred to as information code 40.

[0017] Furthermore, the information code 40 may include personal information including biometric authentication information for biometric authentication. In addition to the biometric authentication information, the personal information may include information such as a mobile phone number, a social security number, a passport number, an account number, a driver's license number, a name, a social insurance number, a date of birth, a place of birth, and a maiden name. The biometric authentication information may include a face image, fingerprint information, iris information, a palm shape, a retina, a blood vessel, a voice, an ear shape, and the like.

[0018] In the information code 40 according to the present embodiment, the information code area 401 in which the specific information is recorded is composed of information cells 402 of three or more colors, and the amount of information that can be recorded is larger than that of 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 that when an image of the entire face is recorded with a resolution that allows 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 the present embodiment, it is possible to record a face image for face recognition in the information code 40 by storing only a part of the face that is a characteristic point in face recognition, such as the user's eyes or mouth, as a face image for face recognition, instead of the entire face of the user.

[0019] The storage unit 15 stores a program for carrying out monetary transactions according to this embodiment, and also stores an information code 40 including balance data of electronic money used in offline monetary transactions and transaction information used in monetary transactions. In this embodiment, the program stored in the storage unit 15 is stored in a state in which reverse engineering or modification of the program itself cannot be performed by using techniques such as obfuscation (for example, measures such as converting names in the source code, such as class names, method names, and variable names, into names that are difficult for humans to read, encrypting character strings including functions, and inserting meaningless loops and Goto statements to make the source code difficult to understand) and encryption. As a result, in this embodiment, it is possible to effectively prevent the seller from illegally modifying the program of the seller terminal 10.

[0020] In this embodiment, the information code 40 stored in the storage unit 15 is also stored in an encrypted state so that data cannot be tampered with. Here, Fig. 5 is a diagram for explaining information contained in the information code 40 stored in the storage unit 15. As shown in Fig. 5, the information code 40 stored in the storage unit 15 includes transaction information such as the seller terminal PID, the purchaser terminal PID, the product name, the transaction amount, the quantity, the subject of the transaction, and the transaction date and time, and this transaction information is encrypted with the private key KS20 of the purchaser terminal 20 (however, the transaction start information code 41 does not include the purchaser terminal PID). As shown in Fig. 5, the information code 40 stored in the memory unit 15 includes the public key KP20 of the purchaser terminal 20 in addition to the encrypted transaction information. The purchaser's public key KP20 is stored in an unencrypted plaintext state. As a result, in this embodiment, the seller terminal 10 can use the purchaser's public key KP20 included in the information code 40 stored in the memory unit 15 to decrypt and use the encrypted transaction information also included in the information code 40. Furthermore, since the transaction information included in the information code 40 stored in the memory unit 15 is encrypted, the stored transaction information itself cannot be tampered with.

[0021] The storage unit 15 can be configured to store the information code 40 as is as image information, or can be configured to store binary data read from the information code 40. When the information code 40 is stored as image information, the encrypted transaction information and the purchaser's public key KP20 contained in the information code 40 can be read from the image information.

[0022] By executing the programs stored in the memory unit 15, the calculation unit 16 realizes a seller transaction function for performing monetary transactions using electronic money 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 will be described below.

[0023] The seller-side transaction function of the seller terminal 10 creates a transaction start information code 41 including transaction information, for example as shown in FIG. 6, by the seller inputting the transaction amount via the input unit 14 or by scanning a barcode printed on a product with the camera 11, and displays the created transaction start information code 41 together with the entered transaction amount on the display 13. In this embodiment, the purchaser terminal 20 reads the transaction start information code 41 displayed by the seller terminal 10, and the payment of electronic money is executed. In this embodiment, the seller-side transaction function can also be configured to create a receipt information code 43 or a cancellation information code 44 including transaction information in a similar manner, and display them on the display 13.

[0024] In this embodiment, when payment is executed at the purchaser terminal 20, a payment completion information code 42 (payment completion image information) indicating the completion of the payment is displayed on the display 23 of the purchaser terminal 20. In this case, the seller transaction function reads the payment completion information code 42 displayed on the purchaser terminal 20 with the camera 11, and increases the terminal balance data of electronic money stored in the storage unit 15 according to the transaction amount. Specifically, in this embodiment, the payment completion information code 42 includes transaction information encrypted with the private key KS20 of the purchaser terminal 20 and the public key KP20 of the purchaser terminal 20. The seller transaction function decrypts the encrypted transaction information included in the payment completion information code 42 using the purchaser's public key KP20 also included in the payment completion information code 42, and can increase the terminal balance data of electronic money stored in the storage unit 15 using the transaction amount data included in the decrypted transaction information. In this way, by reading the payment completion information code 42 displayed on the buyer's terminal 20, the seller terminal 10 can confirm that payment has been completed at the buyer's terminal 20, even when a monetary transaction based on electronic money is conducted offline, making it possible to properly complete the transaction at the seller terminal 10.

[0025] The balance data update function of the seller terminal 10 updates the server balance data stored in the server 30 so that it matches the terminal balance data of electronic money stored in the seller terminal 10 in an environment where network communication such as the Internet line 2 is available. That is, in this embodiment, in an environment where the seller terminal 10 and the buyer terminal 20 can use network communication such as the Internet line 2, monetary transactions based on electronic money can be performed via the server 30 as in the past, and the balance data of the seller carrying the seller terminal 10 is stored in the server 30 as server balance data. On the other hand, in an environment where network communication is not available, the seller terminal 10 cannot access the server 30, so that when an offline monetary transaction according to this embodiment is performed, the terminal balance data stored in the memory unit 15 of the seller terminal 10 and the server balance data stored in the 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.

[0026] The purchaser terminal 20 is an information terminal such as a smartphone, tablet, or laptop computer carried by the purchaser, and as shown in FIG. 3, has a camera 21, a communication unit 22, a display 23, an input unit 24, a storage unit 25, and a calculation unit 26. The camera 21 performs operations such as reading an information code 40 including transaction information displayed on the seller terminal 10. The communication unit 22 communicates with the server 30 in an environment where network communication is available. The display 23 displays a payment completion information code 42 indicating the completion of payment on the screen. The input unit 24 is used by the purchaser to input payment information and the like. It should be noted that a configuration in which the display 23 and the input unit 24 are integrated into a touch display can be used.

[0027] The storage unit 25 also stores a program for carrying out monetary transactions according to this embodiment, as well as an information code 40 including electronic money balance data and transaction information used in monetary transactions. In this embodiment, the program stored in the storage unit 25 is stored in a state in which reverse engineering or modification of the program itself cannot be performed, using techniques such as obfuscation and encryption. This makes it possible to effectively prevent the purchaser from illegally modifying the program of the purchaser terminal 20 in this embodiment.

[0028] In this embodiment, the information code 40 stored in the storage unit 25 is also stored in an encrypted state so that data cannot be tampered with. That is, the information code 40 stored in the storage unit 25, like the information code 40 stored in the storage unit 15 of the seller terminal 10, contains transaction information such as the seller terminal PID, the purchaser terminal PID, the product name, the transaction amount, the quantity, the subject of the transaction, and the transaction date and time in an encrypted state, as shown in Fig. 5, and also contains the seller's public key KP10 in an unencrypted plaintext state. In this embodiment, since the transaction information included in the information code 40 is encrypted, it is possible to effectively prevent the purchaser from illegally altering the transaction information stored in the purchaser terminal 20.

[0029] Furthermore, the calculation unit 26 executes the programs stored in the storage unit 25 to realize a charge function for charging electronic money in an environment where network communication is available, and a purchaser-side transaction function for executing monetary transactions based on electronic money offline. The above programs can be executed in the purchaser-side terminal 20 in the form of an application or app. Each function of the purchaser-side terminal 20 will be described below.

[0030] 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 for inputting the amount to be charged on the display 13, as shown in FIG. 7(A). Then, when the purchaser inputs the charge amount, a charge confirmation screen is displayed, as shown in FIG. 7(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.

[0031] The purchaser's transaction function of the purchaser's terminal 20 executes payment of the monetary transaction based on the transaction start information code 41 including the transaction information displayed by the seller's terminal 10. Specifically, when the purchaser's transaction function reads the transaction start information code 41 including the transaction information displayed by the seller's terminal 10, it extracts the encrypted transaction information and the seller's public key KP10 from the transaction start information code 41. The purchaser's transaction function then decrypts the encrypted transaction information with the seller's public key KP10. The purchaser's transaction function then displays on the screen of the display 13 the balance stored in the memory unit 25 and the balance after payment, in addition to the transaction amount included in the decrypted transaction information, as shown in FIG. 8(A), for example. The purchaser's transaction function also displays a payment button on the screen to request approval of the payment of the transaction. When the purchaser presses the payment button, the purchaser's transaction function displays a confirmation of the payment as shown in Figure 8 (B), and when the purchaser touches "Yes" to approve the payment, the purchaser's transaction function deducts the transaction amount from the terminal balance data stored in the memory unit 25 of the purchaser's terminal 20 and completes the payment. Note that if the transaction amount is greater than the balance in the terminal balance data, the purchaser's transaction function displays an error on the screen of the display 13 as the transaction cannot be executed (or it may display such that the payment button cannot be pressed).

[0032] Furthermore, when the payment is completed, the purchaser's transaction function of the purchaser's terminal 20 creates a payment completion information code 42 indicating the completion of the payment, and displays the created payment completion information code 42 on the display 23, as shown in Fig. 9. The payment completion information code 42 includes transaction information encrypted with the private key KS20 of the purchaser's terminal 20, and the public key KP20 of the purchaser's terminal 20, as shown in Fig. 5. The payment completion information code 42 also includes information indicating that payment of monetary data corresponding to the transaction amount has been completed at the purchaser's terminal 20.

[0033] When the payment is completed at the buyer terminal 20, the payment completion information code 42 is displayed on the display 23, and the seller terminal 10 is made to read the information code 42 indicating the payment completion, so that the seller terminal 10 can confirm the completion of the payment even in an offline monetary transaction. In a conventional online monetary transaction, the seller terminal 10 can confirm the completion of the payment at the buyer terminal 20 via the server 30, but in an offline monetary transaction, the seller terminal 10 cannot access the server 30 and confirm whether the payment is completed at the buyer terminal 20. Therefore, in this embodiment, the payment completion information code 42 indicating the payment completion is displayed on the buyer terminal 20, so that the seller terminal 10 can confirm the completion of the payment even in an offline environment.

[0034] In this embodiment, personal information such as the account numbers, My Number, and biometric authentication information such as face images of the seller and the purchaser are stored in advance in the storage units 15 and 25 of the seller terminal 10 and the purchaser terminal 20. In this embodiment, the storage units 15 and 25 of the seller terminal 10 and the purchaser terminal 20 store terminal balance data held by the seller terminal 10 and the purchaser terminal 20, respectively. It is preferable to encrypt the terminal balance data stored in the storage units 15 and 25 from the viewpoint of ensuring security. For example, a key character string indicating the terminal balance data can be converted by a predetermined function f(x) and further encrypted by RSA encryption. In addition, in order to further increase security, measures to make disassembly of the program difficult to understand are also effective. It is also effective to change the program periodically.

[0035] The server 30 is installed on the Internet line 2, and has a function of exchanging data with the seller terminal 10 and the buyer terminal 20 and making electronic payments when the seller terminal 10 and the buyer terminal 20 can connect to the Internet line 2. As described above, the server 30 stores the balance data of the seller terminal 10 and the buyer terminal 20 as server balance data, and can perform an update process to make the server balance data match the terminal balance data when the terminal balance data of the seller terminal 10 and the buyer terminal 20 do not match the server balance data due to an offline monetary transaction. When performing the update process, in order to prevent fraud, the server 30 can refer to a transaction code or the like and inquire whether the amount increased at the seller terminal 10 matches the amount decreased at the buyer terminal 20 in the monetary transaction between the seller terminal 10 and the buyer terminal 20.

[0036] Next, the offline monetary transaction process according to this embodiment will be described. FIG. 10 and FIG. 11 are flowcharts showing the offline monetary transaction process according to this embodiment. In the offline monetary transaction process shown in FIG. 10 and FIG. 11, it is assumed that the purchaser terminal 20 is charged with and holds electronic money sufficient for the transaction amount in an environment where network communication such as the Internet is available. In the following, it is assumed that the seller terminal 10 is a mobile terminal having a telephone call function such as a smartphone, and that a seller terminal PID for identifying the seller terminal 10 itself is stored in the storage unit 15. Similarly, the purchaser terminal 20 is also a mobile terminal having a telephone call function such as a smartphone, and that a purchaser terminal PID for identifying the purchaser terminal 20 is stored in the storage unit 25 as information for identifying the purchaser terminal 20 itself.

[0037] In step S101, identity authentication is performed in 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 face image is read by the cameras 11, 21 and face authentication is performed. The face authentication method is not particularly limited, and a known method can be used. Furthermore, face information required for face authentication can be captured in advance by the cameras 11, 21 and stored in the storage units 15, 25. Then, in step S102, it is determined whether face authentication has been performed in the seller terminal 10 and the buyer terminal 20. If face authentication has been successful in both the seller terminal 10 and the buyer terminal 20, the process proceeds to step S103. On the other hand, if face authentication has not been performed in either the seller terminal 10 or the buyer terminal 20, the offline monetary transaction process shown in FIG. 10 cannot be continued, so that in step S124, an error message is displayed and the offline monetary transaction process ends.

[0038] In step S103, the seller transaction function of the seller terminal 10 acquires transaction information including the transaction amount of the monetary transaction. For example, the seller can have the purchaser input transaction information such as the product name, transaction amount, quantity, transaction subject, and transaction date and time of the product being sold to the purchaser by scanning the product's barcode or manually inputting the transaction amount, etc., into the input unit 14, and the seller transaction function can acquire this transaction information. Note that the seller transaction function can also be configured to have the seller input transaction information via the input unit 14 by displaying a screen on the display 13 that prompts the seller to input transaction information, and acquire the transaction information entered by the seller.

[0039] In step S104, the seller transaction function of the seller terminal 10 encrypts the transaction information. Specifically, the seller transaction function of the seller terminal 10 encrypts the seller terminal PID stored in the memory unit 15 and the transaction information acquired in step S103 using the seller's private key KS10 also stored in the memory unit 15. The encryption method is not particularly limited, and a publicly known public key encryption method or the like can be used. In addition, in step S104, since the seller transaction function does not acquire the buyer terminal PID, it encrypts the transaction information shown in FIG. 5 except for the buyer terminal PID.

[0040] In step S105, the seller-side transaction function of the seller terminal 10 generates and displays a transaction start information code 41 (transaction start image information) including the encrypted transaction information and the seller's public key KP10. Specifically, the seller-side transaction function acquires the seller's public key KP10 stored in the memory unit 15, and generates a transaction start information code 41 including the transaction information encrypted in step S104, the seller's public key KP10 acquired from the memory unit 15, and information indicating the start of a monetary transaction. Then, the seller-side transaction function displays the generated transaction start information code 41 on the display 13, as shown in FIG. 6. In this embodiment, a color QR code is generated and displayed as the transaction start information code 41, as shown in FIG. 4, but a known method can be used to generate the color QR code.

[0041] In step S106, the purchaser transaction function of the purchaser terminal 20 reads the transaction start information code 41 displayed on the seller terminal 10 in step S105 and stores it in the memory unit 25. Specifically, the purchaser transaction function starts the camera 21 and displays a message urging the purchaser to read the transaction start information code 41 displayed on the seller terminal 10. When the purchaser captures an image of the transaction start information code 41 displayed on the seller terminal 10 with the camera 21, the purchaser transaction function extracts the encrypted transaction information and the seller's public key KP10 from the image data of the read transaction start information code 41. The purchaser transaction function then stores the obtained encrypted transaction information and the seller's public key KP10 in the memory unit 25.

[0042] In step S107, the encrypted transaction information extracted in step S106 is decrypted by the purchaser's transaction function of the purchaser's terminal 20 using the seller's public key KP10 also extracted in step S106. This enables the purchaser's terminal 20 to use the decrypted transaction information for display and balance data calculation.

[0043] In step S108, the purchaser terminal 20 approves the payment. For example, the purchaser transaction function of the purchaser terminal 20 displays on the display 23 a screen showing the transaction amount included in the transaction information decrypted in step S107, the terminal balance data stored in the purchaser terminal 20 and the balance after payment, as well as a payment button, as shown in Fig. 8(A). When the purchaser presses the payment button displayed on the display 23, the purchaser transaction function displays a display requesting approval of the payment on the screen, as shown in Fig. 8(B). In response, when the purchaser gives an instruction to approve the payment via the input unit 24, the purchaser terminal 20 approves the payment.

[0044] In step S109, since the payment has been approved, the electronic money balance data is deducted by the purchaser transaction function of the purchaser terminal 20. For example, as shown in Figures 8(A) and (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.

[0045] In step S110, the transaction information is encrypted by the purchaser-side transaction function of the purchaser-side terminal 20. Specifically, the purchaser-side transaction function adds the identification information of the purchaser-side terminal 20 (purchaser-side terminal PID) stored in the memory unit 25 of the purchaser-side terminal 20 to the transaction information decrypted by the purchaser-side terminal 20 in step S107, and encrypts the transaction information with the purchaser's private key KS20 stored in the memory unit 25. As in step S104, the encryption method is not limited, and a publicly known public key encryption method or the like can be used.

[0046] In step S111, the purchaser-side transaction function of the purchaser-side terminal 20 creates and displays a payment completion information code 42. Specifically, the purchaser-side transaction function acquires the purchaser's public key KP20 stored in the memory unit 25. The purchaser-side transaction function then generates a payment completion information code 42 (payment completion image information) including the transaction information encrypted in step S110, the purchaser's public key KP20 acquired from the memory unit 25, and information indicating that payment has been completed, and displays it on the display 23.

[0047] 11, in step S112, the seller transaction function of the seller terminal 10 determines whether the current monetary transaction has been canceled. For example, the seller terminal 10 can display a button for canceling the current monetary transaction on the display 23 after step S103, and can determine that the current monetary transaction has been canceled when the seller clicks this button. If the current monetary transaction has been canceled, the process proceeds to step S121, whereas if the current monetary transaction has not been canceled, the process proceeds to step S113. The process of step S112 can also be configured to be executed by the buyer transaction function of the buyer terminal 20.

[0048] In step S113, the seller transaction function of the seller terminal 10 reads the payment completion information code 42 displayed on the display 23 of the buyer terminal 20 in step S111, and stores it in the memory unit 15. In addition, in step S114, the seller transaction function of the seller terminal 10 decrypts the encrypted transaction information included in the payment completion information code 42 read in step S113, using the buyer's public key KP20 also included in the payment completion information code 42. This allows the seller terminal 10 to obtain the decrypted transaction information from the payment completion information code 42 displayed on the buyer terminal 20.

[0049] In step S115, the seller transaction function of the seller terminal 10 compares whether the transaction information stored in the seller terminal 10 matches the transaction information included in the payment completion information code 42 displayed on the buyer terminal 20. If it is determined in step S116 that the transaction information matches, the process proceeds to step S117, and if it is determined that the transaction information does not match, the process proceeds to step S124, where an error message such as "This is a different transaction. Please check the item being purchased and the buyer, and then photograph the information code again" is output.

[0050] In step S117, the seller transaction function of the seller terminal 10 increments the terminal balance data of the seller terminal 10 based on the transaction information decrypted in step S114. Specifically, the seller transaction function confirms that the payment has been completed at the buyer terminal 20 based on the information indicating payment completion contained in the payment completion information code 42, and increments the terminal balance data of the electronic money of the seller terminal 10 by the amount of the transaction.

[0051] In step S118, the seller transaction function of the seller terminal 10 encrypts the transaction information for this monetary transaction with the seller's private key KS10, and in the following step S119, the seller transaction function generates a receipt information code 43 including the transaction information encrypted in step S118, the seller's public key KP10 stored in the memory unit 15, and information indicating that it is a receipt, and displays this on the display 13.

[0052] In step S120, the receipt information code 43 displayed on the display 13 of the seller terminal 10 is read by the camera 21 through the buyer's transaction function of the buyer's terminal 20, and stored in the memory unit 25. As a result, evidence that the transaction was properly conducted is stored in the memory unit 25 at the buyer's terminal 20.

[0053] If the current monetary transaction is canceled in step S112, the process proceeds to step S121. In step S121, a cancellation information code 44 for canceling the current monetary transaction is generated and displayed by the seller transaction function of the seller terminal 10. The cancellation information code 44 can be configured to include information indicating that the current monetary transaction is to be canceled, and can also be configured to include transaction information related to the current monetary transaction (for example, the seller terminal PID, the buyer terminal PID, the product name, the transaction amount, the quantity, the subject of the transaction, and the transaction date and time) as shown in FIG.

[0054] In step S122, the purchaser-side transaction function of the purchaser-side terminal 20 reads the cancellation information code 44. The purchaser-side transaction function can read the cancellation information code 44 by capturing an image of the cancellation information code 44 displayed on the display 13 of the seller terminal 10 in step S121 with the camera 11. Then, in step S123, the purchaser-side transaction function of the purchaser-side terminal 20 performs a process of canceling the deduction from the terminal balance data. Specifically, the purchaser-side transaction function obtains information indicating that the current monetary transaction is to be cancelled, which is included in the cancellation information code 44 read in step S122, and performs a process of restoring the terminal balance data deducted in step S109 to its original value. In addition, if the cancellation information code 44 is configured to include, in addition to information indicating that the current monetary transaction is to be canceled, transaction information such as the seller terminal PID, buyer terminal PID, product name, transaction amount, quantity, transaction subject, and transaction date and time for this monetary transaction, the buyer's transaction function can be configured to refer to this transaction information to identify the current transaction record and restore the monetary data that was deducted in the monetary transaction.

[0055] As described above, the offline monetary transaction process shown in Figs. 10 and 11 is performed. At the end of the offline monetary transaction process, the terminal balance data of the seller terminal 10 and the server balance data of the seller terminal 10 stored in the server 30 do not match. Therefore, the data update function of the seller terminal 10 accesses the server 30 when the environment becomes available for network communication after the offline monetary transaction process, and updates the server balance data stored in the server 30 so that the server balance data matches the terminal balance data stored in the seller terminal 10. Similarly, at the end of the offline monetary transaction process, the terminal balance data of the buyer terminal 20 and the server balance data of the buyer terminal 20 stored in the server 30 do not match. Therefore, the data update function of the buyer terminal 20 accesses the server 30 when the environment becomes available for network communication after the offline monetary transaction process, and updates the server balance data stored in the server 30 so that the server balance data matches the terminal balance data stored in the buyer terminal 20.

[0056] For example, in an environment where online communication is possible, the purchaser terminal 20 can transmit the terminal balance data of the purchaser terminal 20 to the server 30 together with the transaction information acquired from the seller terminal 10. Furthermore, when the purchaser terminal 20 has made monetary transactions with multiple seller terminals 10, it can transmit multiple pieces of transaction information acquired from each of the multiple seller terminals 10 to the server 30. In this case, the server 30 can update the server balance data of the purchaser terminal 20 by subtracting the amount of the transaction amount included in the transaction information from the server balance data of the purchaser terminal 20 before the update stored in the server 30 based on the history of the transaction information (or multiple pieces of transaction information) acquired from the purchaser terminal 20. The server 30 can be configured to determine whether the updated server balance data of the purchaser terminal 20 matches the terminal balance data of the purchaser terminal 20 transmitted from the purchaser terminal 20, and output an error to the purchaser terminal 20 if they do not match.

[0057] Similarly, in an environment where online communication is possible, the seller terminal 10 can transmit the terminal balance data of the seller terminal 10 to the server 30 together with the transaction information acquired from the buyer terminal 20. Furthermore, when the seller terminal 10 has performed monetary transactions with a plurality of buyer terminals 20, it can transmit a plurality of pieces of transaction information acquired from the plurality of buyer terminals 20 to the server 30. In this case, the server 30 can update the server balance data of the seller terminal 10 by increasing the amount of the transaction amount included in the transaction information based on the history of the transaction information (or a plurality of pieces of transaction information) acquired from the seller terminal 10, with respect to the server balance data of the seller terminal 10 before the update stored in the server 30. The server 30 can be configured to determine whether the updated server balance data of the seller terminal 10 matches the terminal balance data of the seller terminal 10 transmitted from the seller terminal 10, and output an error to the seller terminal 10 if they do not match.

[0058] In the above-described embodiment, the buyer terminal 20 sends transaction information to the server 30 to update the server balance data of the buyer terminal 20, and the seller terminal 10 sends transaction information to the server 30 to update the server balance data of the seller terminal 10, but the present invention is not limited to this configuration. For example, the server balance data of both the seller terminal 10 and the buyer terminal 20 can be updated by one of the seller terminal 10 or the buyer terminal 20 sending transaction information to the server 30. For example, when the seller terminal 10 sends transaction information to the server 30, the server 30 can update the server balance data of the seller terminal 10 and also update the server balance data of the buyer terminal 20 that has made a monetary transaction with the seller terminal 10.

[0059] 10 and 11, an example is shown in which an offline monetary transaction is initiated by a seller inputting transaction information including a transaction amount into the seller terminal 10, but the present invention is not limited to this configuration, and for example, an offline monetary transaction can be initiated by a buyer inputting transaction information including a transaction amount into the buyer terminal 20. For example, a QR code including the seller's identification information is placed in a store, and the buyer reads the QR code using the buyer terminal 20, and further inputs the product, quantity, transaction amount, transaction subject, etc., and approves the payment, thereby achieving a state in which step S108 of the offline monetary transaction process described above has been performed.

[0060] Next, the effect of preventing data tampering in the monetary transaction system 1 according to this embodiment will be described. In the offline monetary transaction process shown in Figures 10 and 11, for example, if a purchaser tries to fraudulently tamper with the transaction amount of the transaction information included in the transaction start information code 41 stored in the memory unit 25 of the purchaser terminal 20 to zero or an amount less than the original transaction amount before approving the payment at the purchaser terminal 20, in this embodiment, since the transaction information included in the transaction start information code 41 stored in the memory unit 25 of the purchaser terminal 20 is stored in a state encrypted with the seller's private key KS10, the transaction amount of the encrypted transaction information cannot be tampered with, and fraudulent data tampering by the purchaser can be prevented. Similarly, if a seller attempts to tamper with the current transaction amount to make it higher than the actual transaction amount in order to fraudulently increase the terminal balance data of the seller terminal 10, in this embodiment, the transaction information contained in the payment completion information code 42 stored in the memory unit 15 of the seller terminal 10 is stored in an encrypted state with the purchaser's private key KS20, so that the transaction amount of the encrypted transaction information cannot be tampered with, and such fraudulent data tampering by a seller can be prevented.

[0061] As described above, in this embodiment, the first information terminal or the second information terminal is configured to store transaction information encrypted with the private key of the other information terminal, so that the encrypted transaction information stored in the first information terminal or the second information terminal can be effectively prevented from being tampered with. In addition, the first information terminal or the second information terminal can easily use the encrypted transaction information stored in the first information terminal or the second information terminal by obtaining a public key from the other information terminal using the public key. In addition, in the first information terminal or the second information terminal, the money transaction program can be obfuscated or encrypted to prevent the program itself from being tampered with, and the security of the program itself can be improved by performing a tampering check to detect tampering if the program is tampered with.

[0062] Although the preferred embodiment of the present invention has been described above, the technical scope of the present invention is not limited to the description of the above embodiment. Various modifications and improvements can be made to the above embodiment, and such modifications and improvements are also included in the technical scope of the present invention.

[0063] For example, in the above-described embodiment, from the viewpoint of privacy protection, the seller terminal 10 and the buyer terminal 20 can be configured not to exchange data that can identify the seller terminal 10 and the buyer terminal 20. For example, the seller terminal 10 and the buyer terminal 20 can be configured to display, as transaction information, an information code 40 that includes only data on a transaction code and a transaction amount, so that the system cannot track information such as who a transaction was made with and what the transaction was, just as in a monetary transaction using only actual currency.

[0064] In addition, in the above-described embodiment, electronic money is 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.

[0065] In addition, in the above-mentioned embodiment, as shown in FIG. 4, the information code 40 is configured such that the teacher code region 403 is arranged on the lower left side of the information code region 401, but the position of the teacher code region 403 is not particularly limited, and for example, the teacher code region 403 may be arranged on the upper side or the lower right side of the information code region 401. In addition, in the example shown in FIG. 4, the teacher code region 403 is arranged so as to be in contact with the information code region 401, but it may be arranged at a position away from the information code region 401. In addition, in the example shown in FIG. 4, the information code 40 is configured to have only one teacher code region 403, but it is not limited to this configuration, and it may be configured to have a plurality of teacher code regions 403, such as one teacher code region 403 arranged on the upper side and one teacher code region 403 arranged on the lower side of the information code region 401. In addition, the information code 40 may be configured such that one or more teacher code regions 403 are arranged inside the information code region 401. [Explanation of symbols]

[0066] 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 terminal 21. Camera 22…Communications Department 23…Display 24...Input section 25...Storage section 26...Arithmetic section 30…Server 40...Information code 41…Trading start information code 42...Payment completion information code 43...Receipt information code 44…Cancellation 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, the system executing a monetary transaction based on monetary data between the first information terminal and the second information terminal offline, The first information terminal is a first storage means for storing first balance data held by the first information terminal and a private key and a public key of the first information terminal; A first acquisition means for acquiring data on a transaction amount in the monetary transaction; an encryption means for encrypting transaction information including data on a transaction amount acquired by the first acquisition means with a private key of the first information terminal; a money processing means for increasing or decreasing the first balance data based on the transaction amount data acquired by the first acquisition means; a first display means for displaying image information including the encrypted transaction information and a public key of the first information terminal on the first image display unit, The second information terminal is a second storage means for storing second balance data held by the second information terminal; a second image reading means for causing the second image reading unit to read the image information displayed by the first information terminal; a second acquiring means for acquiring the encrypted transaction information and a public key of the first information terminal from the image information; a decryption means for decrypting the encrypted transaction information by using a public key of the first information terminal; and a money processing means for increasing or decreasing the second balance data based on transaction amount data included in the transaction information decrypted by the decryption means.

2. 2. The monetary transaction system according to claim 1, wherein the second information terminal stores the transaction information in an encrypted state.

3. the second information terminal stores a private key and a public key of the second information terminal in the second storage means, The second information terminal is a second encryption means for encrypting the transaction information acquired from the first information terminal with a private key of the second information terminal; The monetary transaction system of claim 1, further comprising a second display means for displaying image information on the second image display unit, the image information including the transaction information encrypted by the second encryption means and the public key of the second information terminal.

4. A first information terminal in a money transaction system for executing a money transaction based on money data between a first information terminal and a second information terminal offline, a first storage means for storing first balance data held by the first information terminal and a private key and a public key of the first information terminal; A first acquisition means for acquiring data on a transaction amount in the monetary transaction; an encryption means for encrypting transaction information including data on a transaction amount acquired by the first acquisition means with a private key of the first information terminal; a money processing means for increasing or decreasing the first balance data based on the transaction amount data acquired by the first acquisition means; a first display means for displaying image information including the encrypted transaction information and the public key of the first information terminal; The image information displayed by the first display means is read by the second information terminal, and in the second information terminal, the balance data of the second information terminal is increased or decreased based on the encrypted transaction information contained in the image information and the public key of the first information terminal.

5. A second information terminal in a money transaction system that executes a money transaction based on money data between a first information terminal and a second information terminal offline, the first information terminal has a means for displaying image information including transaction information including transaction amount data encrypted with a private key of the first information terminal and a public key of the first information terminal for decrypting the encrypted transaction information; The second information terminal is a second storage means for storing second balance data held by the second information terminal; a second image reading means for reading the image information displayed by the first information terminal; a second acquiring means for acquiring the encrypted transaction information and a public key of the first information terminal from the image information; a decryption means for decrypting the encrypted transaction information by using a public key of the first information terminal; and a money processing means for increasing or decreasing the second balance data based on transaction amount data included in the transaction information decrypted by the decryption means.

6. 6. The information terminal according to claim 5, wherein the transaction information is stored in an encrypted state.

7. A server capable of communicating with the information terminal according to claim 4 and the information terminal according to claim 5 or 6, a server storage unit that stores the first balance data held by the first information terminal and / or the second balance data held by the second information terminal as server balance data; A server having an update unit that acquires the first balance data and / or the second balance data as terminal balance data from the first information terminal and / or the second information terminal, acquires the transaction information, and updates the server balance data stored in the server memory unit based on the acquired terminal balance data and the transaction information.

8. A monetary transaction system including 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 a monetary transaction based on monetary data between the first information terminal and the second information terminal offline, comprising: a computer program executed by the first information terminal, a function of storing first balance data held by the first information terminal and a private key and a public key of the first information terminal; A function of acquiring data on the transaction amount of the monetary transaction; a function of encrypting transaction information including the acquired transaction amount data with a private key of the first information terminal; A function of increasing or decreasing the first balance data based on the acquired transaction amount data; a display function for displaying image information including the encrypted transaction information and the public key of the first information terminal; A computer program in which the image information displayed by the display function is read by the second information terminal, and the balance data of the second information terminal is increased or decreased in the second information terminal based on the encrypted transaction information contained in the image information and the public key of the first information terminal.

9. A monetary transaction system including 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 a monetary transaction based on monetary data between the first information terminal and the second information terminal offline, comprising: a computer program executed by the second information terminal, the first information terminal has a means for displaying image information including transaction information including data of a transaction amount encrypted with a private key of the first information terminal and a public key of the first information terminal; The computer program of the second information terminal comprises: a function of storing second balance data held by the second information terminal; a function of causing the second image reading unit to read the image information displayed by the first information terminal; a function of acquiring the encrypted transaction information and a public key of the first information terminal from the image information; a function of decrypting the encrypted transaction information by using a public key of the first information terminal; and increasing or decreasing the second balance data based on transaction amount data included in the decrypted transaction information.

10. The computer program product according to claim 9 , further comprising a function for storing the transaction information in an encrypted state.

11. A monetary transaction method executed by a first information terminal, the 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, when performing a monetary transaction based on monetary data between the first information terminal and the second information terminal offline, the method comprising: a first balance data held by the first information terminal and a private key and a public key of the first information terminal are stored; Acquire data on the transaction amount of the monetary transaction; encrypting transaction information including the acquired transaction amount data with a private key of the first information terminal; Increasing or decreasing the first balance data based on the acquired transaction amount data; displaying image information including the encrypted transaction information and the public key of the first information terminal; A method of monetary transaction, wherein the image information displayed by the first information terminal is read by the second information terminal, and the balance data of the second information terminal is increased or decreased in the second information terminal based on the encrypted transaction information contained in the image information and the public key of the first information terminal.

12. A monetary transaction method executed by 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, when performing a monetary transaction based on monetary data between the first information terminal and the second information terminal offline, the method comprising: the first information terminal has a means for displaying image information including transaction information including data of a transaction amount encrypted with a private key of the first information terminal and a public key of the first information terminal; The second information terminal is The second information terminal stores second balance data held by the second information terminal, reading the image information displayed by the first information terminal by the second image reading unit; obtaining the encrypted transaction information and a public key of the first information terminal from the image information; decrypting the encrypted transaction information using a public key of the first information terminal; A monetary transaction method, comprising:increasing or decreasing the second balance data based on transaction amount data included in the decrypted transaction information.

Images