External authentication circuit board for smartphone

Abstract

[Problem] To mount an authentication circuit board equipped with an NFC chip on a smartphone, and enable usage as a hardware token of an authentication means for multi-factor authentication in order to prevent SIM swap fraud or the like. To provide an authentication circuit board, in which an NFC card with fingerprint authentication functions can be used by a smartphone as an additional fingerprint authentication means for further multi-factor authentication. [Solution] According to the present invention, necessary electric power can be supplied by bending a part of an authentication circuit board so as to cover a part of a side face of a smartphone, and allowing a magnetic flux of an alternating magnetic field, generated at a non-contact IC card reader, to pass through a coil in the authentication circuit board. An NFC chip in the authentication circuit board is recognized by initial response of NFC communication with the non-contact IC card reader, whereby continuous power feed to an NFC card with fingerprint authentication functions is performed, and the fingerprint authentication functions can be used by the smartphone.

Description

External authentication circuit board for smartphones

[0001] The present invention relates to an external authentication circuit board that can be attached to a smartphone with a built-in contactless IC card reader as a hardware token, and that has an NFC chip, which is an IC chip with a function to communicate via NFC (Near Field Communication), in order to prevent SIM swap fraud and the like, and can be used as one of the authentication means for multi-factor authentication, and also to an NFC card with a fingerprint authentication function that can be used on the smartphone as an additional fingerprint authentication means for multi-factor authentication.

[0002] Smartphones are used in a variety of fields in recent years. To prevent unauthorized use of smartphones by others, smartphones are equipped with several identity verification functions. For example, they can be locked to prevent operation after a certain period of time has passed since the start of operation, preventing others from using the smartphone. In addition to password authentication, such as entering a four-digit number to unlock the smartphone, it has become commonplace for smartphones to be equipped with more secure biometric authentication functions such as fingerprint authentication and facial recognition. In addition to unlocking the smartphone, these biometric authentication functions are increasingly being used for identity verification when paying for online shopping.

[0003] Damages caused by cyber attacks have been increasing rapidly in recent years. The most significant damages to individuals are phishing scams, and to corporations are ransomware attacks. Phishing scams involve sending emails from spoofed senders, leading victims to fake websites in order to steal personal information such as passwords and credit card information.

[0004] Ransomware is a type of malware that infiltrates a target's system by using passwords obtained through phishing scams, etc., then encrypts the data and demands a ransom. Increasingly, the method of intrusion is to exploit vulnerabilities in network devices to infiltrate internal networks, but even in this case, security is breached by using passwords that have been leaked in the past or by using a brute force attack to find out the password.

[0005] As such, traditional authentication methods using IDs and passwords alone cannot be considered secure against cyberattacks, and there is a growing opinion that we should switch to passwordless authentication, which does not require passwords, or multi-factor authentication, which combines several authentication methods. FIDO2 and Passkey are becoming standardized passwordless authentication methods, and since biometric authentication functions such as fingerprint and facial recognition built into smartphones can be used as authenticators, there is no need to purchase new hardware. Furthermore, with FIDO2, in addition to authentication via smartphone, authentication can also be performed on the PC by connecting the PC and smartphone via Bluetooth (registered trademark), using the biometric authentication functions built into the smartphone.

[0006] One-time passwords used for online banking and other purposes have traditionally been provided by hardware tokens, but these have had to be replaced every few years due to the battery life that runs the internal clock, and it is inconvenient to carry a hardware token to each bank when using online banking on a smartphone.As a result, many authentication functions are now being built into smartphones, such as providing one-time password functions as authentication apps that can be installed on smartphones as software.

[0007] Currently, as a countermeasure against phishing scams, the switch to passwordless authentication and multi-factor authentication is progressing rapidly. This has had a deterrent effect against phishing scams. However, a new cyber attack method called SIM swap fraud is beginning to cause damage. In SIM swap fraud, the perpetrator first obtains the target victim's personal information through phishing scams or other methods, and then prepares a counterfeit driver's license or other document. Then, the perpetrator impersonates the victim and reports the loss of the smartphone to the mobile phone carrier, and takes over the victim's phone number by having the SIM reissued or other methods.

[0008] By hijacking a phone number, the perpetrator can receive all SMS messages and calls sent to the victim. This allows them to circumvent SMS authentication, which is widely used for two-step authentication. Even for social media accounts that do not use SMS authentication, the perpetrator can change the password by resetting it using SMS authentication. Some people argue that SMS authentication is risky for SIM swap scams, so they should switch to authentication apps. However, the reality is that very few people realize that this type of opinion is a mistaken one derived from a naive understanding of SIM swap scams.

[0009] When changing the model of an authentication app installed on a smartphone, it is common to reinstall the authentication app and authenticate using the registered phone number, etc. This allows the app to be used in the same way as before the model change. In other words, the current security system is built on the assumption that "the person who owns the phone number is the person in question." SIM swap perpetrators can exploit this to easily reinstall the authentication app on a new device and perform authentication. As can be easily understood from the above explanation, authentication using an authentication app cannot prevent SIM swap fraud.

[0010] Similarly, with biometric authentication such as fingerprint or face recognition built into smartphones, if you change your phone model, you can still authenticate using your registered phone number by reinstalling the application software. It's important to remember that a SIM swapper can easily register their own biometric information on a new device. This means they can successfully authenticate using their own biometric information. The scary thing is that biometric authentication built into smartphones cannot prevent SIM swap fraud.

[0011] Therefore, when a SIM swap occurs, most authentication methods, such as smartphone biometric authentication and authentication apps, can be invalidated. In other words, the current situation is extremely dangerous. This is because, as mentioned above, existing authentication methods are built on the assumption that "it is the person who owns the phone number" and security cannot be ensured based on the assumption that "it is the person who owns the phone number." Therefore, it is urgent to correctly understand this naivety and fundamentally rebuild security based on the perspective that SIM swaps allow "a malicious third party to obtain a phone number." Unfortunately, a correct understanding of SIM swaps is not widely known, and the only countermeasures currently proposed are stricter identity verification by mobile phone carriers when reissuing SIM cards.

[0012] Furthermore, until now, SIM swap fraud has mostly involved the theft of personal bank deposits and virtual currencies, and has been thought to have little relevance to the security of large corporate networks. In August 2023, the U.S. Department of Homeland Security reportedly released a report summarizing the results of its Cybersecurity Review Board's investigation into the threat actor "Lapsus$." According to the report, "Lapsus$" has successfully infiltrated dozens of organizations, including Microsoft, using SIM swapping and other attack methods. As this report shows, SIM swapping is not only being used for "SIM swap fraud" targeting personal assets, but is also beginning to be used as a "SIM swap attack" to bypass multi-factor authentication when infiltrating large corporate networks. It is necessary to quickly popularize multi-factor authentication methods that can counter SIM swap attacks.

[0013] SIM swap attacks primarily disable biometric authentication built into smartphones and authentication apps installed on smartphones. If the authentication function is provided by hardware separate from the smartphone, even if the victim's phone number is transferred from one smartphone to another via a SIM swap, the perpetrator will not be able to successfully authenticate because the hardware with the authentication function remains in the victim's possession. Therefore, SIM swap attacks can be prevented by using authentication using hardware with authentication functions, i.e., a hardware token, as part of multi-factor authentication.

[0014] There are several types of hardware tokens. However, none are user-friendly for use with smartphones for multi-factor authentication. Types that use one-time passwords require users to enter numbers or other information displayed on the hardware token into their smartphone. USB-connected types eliminate the need for manual entry, and some even incorporate biometric authentication features such as fingerprint authentication. However, they require a wired connection between the smartphone and the hardware token. Smartphones are equipped with a wired connector that also serves as a charger. Using this connector to connect a hardware token via a wired connection requires a cable or direct connection each time authentication is required. As can be seen from the above explanation, a cabled connection is inconvenient, and a direct connection increases the risk of damaging the hardware token or the smartphone if the smartphone is dropped. Therefore, USB-connected hardware tokens are not practical for smartphone multi-factor authentication.

[0015] The inventors of this application determined that the best way to connect to a hardware token is through NFC communication using the contactless IC card reader built into most smartphones. NFC communication allows power to be supplied from the smartphone's contactless IC card reader. This eliminates the need for a battery in the hardware token, eliminating the need to replace the hardware token every few years and eliminating the need for maintenance such as charging. NFC has a shorter communication distance than Bluetooth, reducing the risk of communication interception. Furthermore, NFC cards with fingerprint authentication functionality using ultra-thin capacitive fingerprint sensors are commercially available, making it possible to use fingerprint authentication as a multi-factor authentication method.

[0016] When using an NFC-connected hardware token as possession information for authentication, it is sufficient to simply fix it in a position on the smartphone where NFC communication is possible. Therefore, usability is not an issue as long as it can be used in a permanently attached state, either directly to the smartphone or via a smartphone case. The inventors of the present application, for example, used an iPhone (registered trademark) from Apple Inc. in the United States, and verified the operable position using a commercially available FeliCa (registered trademark) card as an NFC-connected hardware token. Herein, the side of the iPhone (i.e., smartphone) on which the display screen is located is referred to as the "display side," and the side opposite the display screen, i.e., the side where the camera lens is located, is referred to as the "display back." On some types of iPhones, the FeliCa card did not work when placed within the frame of the iPhone's display back, but only worked when it protruded significantly beyond the display back of the iPhone. If the FeliCa card protrudes significantly from the smartphone, it is difficult to use the smartphone with the FeliCa card permanently attached.

[0017] Furthermore, contactless IC card readers built into smartphones are also used to read NFC cards, make cashless payments, etc. For this reason, it is necessary to ensure that NFC-connected hardware tokens do not interfere with NFC communication when used to read other NFC cards, make cashless payments, etc. From this perspective, there is a problem in that the types of NFC chips that can be used as hardware tokens are limited.

[0018] If commercially available NFC cards with fingerprint authentication functions could be connected to smartphones via NFC and used as hardware tokens, authentication would be possible using not only possession information but also biometric information. For this reason, even if the authentication operation is time-consuming, it would be preferable to use them in situations where high security is required, such as when transferring money via online banking. There are mainly two types of commercially available NFC cards with fingerprint authentication functions. One is designed for security purposes, and the other is designed for credit card use.

[0019] The former, i.e., NFC cards with fingerprint authentication functionality designed for security purposes, only function as an NFC card if fingerprint authentication is successful, and has the advantage of being immune to skimming if fingerprint authentication is unsuccessful. Furthermore, because they do not have a built-in battery, a contactless IC card reader that can provide continuous power is required. However, fingerprint authentication functionality can be added to electronic locks, access control systems, attendance management systems, and other systems that use NFC cards without any system modifications. However, despite attempting to establish an NFC connection on an iPhone by changing various application software parameters, the built-in contactless IC card reader could not be set to a continuous power state, and an NFC connection with an NFC card with fingerprint authentication functionality designed for security purposes was not possible.

[0020] The latter, that is, NFC cards with fingerprint authentication functions designed for credit cards, have NFC chips that can operate even without fingerprint authentication. This not only poses a risk of skimming, but also outputs the same UID (fixed ID number) both before and after fingerprint authentication is successful. This means that systems that use NFC cards, such as electronic locks, access control systems, and attendance management systems, require system changes. Furthermore, on iPhones, it is difficult to confirm that fingerprint authentication has been successful due to iOS limitations.

[0021] The purpose of this invention is to provide a multi-factor authentication method that is effective even when the SIM card is swapped, as an external authentication circuit board for smartphones, at a low cost, to protect smartphone users from cyber attacks without compromising the usability of the smartphone. Furthermore, in situations where higher security is required, fingerprint authentication using an NFC card with fingerprint authentication function can be used.

[0022] According to one aspect of the present invention, the above-mentioned object is achieved by providing an external authentication circuit board for a smartphone that can be attached to a smartphone with a built-in contactless IC card reader and that can operate the smartphone while the board is attached, the external authentication circuit board for a smartphone comprising: a first NFC chip that has the function of performing NFC communication with the contactless IC card reader; and a first coil that receives power from the contactless IC card reader, wherein a portion of the first coil covers a portion of a side surface of the smartphone so that the magnetic flux of an alternating magnetic field generated by the contactless IC card reader passes through the first coil, thereby enabling the first NFC chip to supply the power necessary for NFC communication with the contactless IC card reader, thereby enabling the authentication circuit board to be used as one of the multi-factor authentication means on the smartphone.

[0023] According to a preferred embodiment of the present invention, the authentication circuit board has a function of adding fingerprint authentication in addition to the multi-factor authentication means using the first NFC chip in the authentication circuit board by attaching the authentication circuit board to a smartphone with a built-in contactless IC card reader and enabling the use of an NFC card with fingerprint authentication function, and the NFC card with fingerprint authentication function comprises fingerprint authentication means including a fingerprint sensor, a fingerprint authentication unit, a memory for storing fingerprint data for comparison, a second coil for receiving power from the contactless IC card reader, and a second NFC chip for performing NFC communication with the contactless IC card reader, and the fingerprint authentication means has a fingerprint data reading function for starting to read fingerprint data using the fingerprint sensor when the second coil receives power from the contactless IC card reader, and a fingerprint data matching function for matching the read fingerprint data with the fingerprint data for comparison stored in the memory by the fingerprint authentication unit, the smartphone has a built-in fingerprint authentication function having a fingerprint authentication notification function that performs the NFC communication from the second NFC chip to the contactless IC card reader only when the fingerprint authentication unit authenticates the fingerprint as the same, and notifies the reader that the fingerprint has been authenticated as the same; the fingerprint sensor, the fingerprint authentication unit, the memory, and the second NFC chip operate only with the power received by the second coil; the smartphone is a model in which continuous power supply from the contactless IC card reader to the second coil cannot be performed by application software installed thereon alone; when power is received from the contactless IC card reader by a first coil in an authentication circuit board, the first NFC chip is recognized in an initial response to the NFC communication, thereby continuous power supply from the contactless IC card reader to the second coil; the fingerprint authentication unit completes the fingerprint authentication; and if the fingerprint authentication is successful, the fingerprint authentication notification is sent.

[0024] The external authentication circuit board for a smartphone according to the present invention preferably further includes a control circuit for controlling the operation timing of the first NFC chip, and enables the first NFC chip when the first coil receives power. This stops the operation of the first NFC chip after a sufficient time has passed for it to be used as one of the multi-factor authentication means. This makes it possible to prevent the contactless IC card reader from interfering with NFC communication with other NFC chips.

[0025] The external authentication circuit board for smartphones according to the present invention can be constructed using a very thin circuit board, so it can be incorporated into a smartphone case without increasing its thickness. Furthermore, it can be manufactured using the same inexpensive manufacturing processes as commercially available NFC labels, enabling it to be mass-produced at low cost.

[0026] FIG. 5 is an explanatory diagram for explaining the arrangement of a first coil with respect to a smartphone. FIG. 6 is a cross-sectional view for explaining the relative position of a smartphone and an NFC card. FIG. 7 is a cross-sectional view for explaining the relative position of a smartphone and an NFC card. FIG. 8 is a block diagram of a fingerprint authentication system related to the present invention. FIG. 9 is a flowchart for explaining an example of the operation of application software installed on a smartphone for controlling the fingerprint authentication system related to the present invention on the smartphone side. FIG. 10 is a timing chart of a first example for explaining the state of power supply to the coil. FIG. 11 is a timing chart of a second example for explaining the state of power supply to the coil. FIG. 12 is a timing chart of a third example for explaining the state of power supply to the coil. FIG. 13 is a cross-sectional view for explaining the fingerprint authentication system of FIG. 4.

[0027] FIG. 1 is a diagram relating to an embodiment of the present invention, and is an explanatory diagram illustrating the arrangement of coils of an authentication circuit board relative to a smartphone and a contactless IC card reader. In the figure, reference symbol 1 denotes an authentication circuit board. Reference symbol 2 denotes a first NFC chip having an NFC communication function, typically a FeliCa (registered trademark) chip. Reference symbol 3 denotes a control circuit that controls the operation timing of the first NFC chip 2. Reference symbol 4 denotes a first coil that receives power from the contactless IC card reader of the smartphone. The first coil 4 supplies power to electronic components mounted on the authentication circuit board. Reference symbol 5 denotes a smartphone. Reference symbol 6 denotes a contactless IC card reader built into the smartphone 5. Reference symbol CL denotes a camera lens, which is located on the back of the display of the smartphone 5.

[0028] Figures 2 and 3 are cross-sectional views illustrating the relative positions of the smartphone 5 and the coil. In Figures 2 and 3, the same reference numerals are used for elements that are the same as those shown in Figure 1. Reference numeral 7 denotes a FeliCa card, etc., such as a commercially available FeliCa card as an authentication circuit board, or a FeliCa card or the like equipped with a FeliCa chip as an NFC chip, such as a sticker or flexible substrate module with equivalent functionality (hereinafter referred to as "FeliCa card, etc. 7"). The inventors of the present application verified the position where NFC communication is possible, i.e., the placement position of the FeliCa card, etc. 7, when the FeliCa card, etc. 7 is applied to an iPhone from Apple Inc. In these FeliCa cards, etc. 7, power is supplied to the NFC chip installed in the FeliCa card, etc. 7 when the built-in first coil 4 receives wireless power from the contactless IC card reader 6. The NFC chip operates continuously during the power supply period. There are no significant differences between types of FeliCa cards, etc. 7, except for the size of the coil.

[0029] When the FeliCa card 7 was used as an authentication circuit board on some iPhones and placed within the frame on the back of the iPhone display as shown in Figure 2, the FeliCa card 7 did not work. On the other hand, when the FeliCa card 7 was placed near the non-contact IC card reader 6 in a manner that it significantly protruded from the frame on the back of the iPhone display as shown in Figure 3, it did work.

[0030] The present inventors investigated the reason why the FeliCa card 7 worked when placed so that it extended significantly beyond the bounds of the iPhone's back display, as shown in Figure 3, but did not work when placed so that it fit within the bounds of the iPhone's back display, as shown in Figure 2. The present inventors came to the following conclusion: The alternating magnetic field generated by the non-contact IC card reader 6 built into the iPhone mainly emanates from the side of the iPhone, and unless the FeliCa card 7 is placed so that the magnetic flux of this alternating magnetic field passes through the first coil 4, sufficient power cannot be supplied to operate the NFC chip. However, if the authentication circuit board 1 is flat, as shown in Figure 3, the authentication circuit board 1 will extend significantly beyond the bounds of the iPhone's back display.

[0031] In FIG. 1 , the authentication circuit board 1 is partially or entirely made of a flexible printed circuit board or the like. This allows the authentication circuit board 1 to be shaped in any desired bent form. In the embodiment, a portion of the authentication circuit board 1 is bent to cover the back and side surfaces of the smartphone 5. This allows the magnetic flux of the alternating magnetic field generated by the non-contact IC card reader 6 to pass through the first coil 4. Furthermore, the authentication circuit board 1 can be installed without significantly protruding from the outer contour of the smartphone 5, and the authentication circuit board 1 becomes operational. For testing purposes, the inventors carefully bent a commercially available FeliCa card into the shape shown in FIG. 1 to prevent the internal wiring from breaking, creating a prototype. This prototype was then attached to an iPhone as shown in FIG. 1 . The inventors then used this prototype to confirm its operation. The results confirmed that the FeliCa chip (first NFC chip 2) in the FeliCa card (authentication circuit board 1) was activated by power supplied from the contactless IC card reader 6 built into the iPhone, enabling NFC communication.

[0032] In the authentication circuit board 1 arranged as shown in FIG. 1, a FeliCa chip was used as the first NFC chip 2 that performs NFC communication with the contactless IC card reader 6 to confirm its operation. The purpose of this operation check was to confirm that sufficient power could be supplied from the contactless IC card reader 6 to the first coil 4. As a result, operation was successfully confirmed. The following can be said from the results of this operation check: As long as the NFC chip supports wireless communication according to the NFC standard, other NFC chips such as Mifare (registered trademark) can also be used and operate without any problems.

[0033] When the authentication circuit board 1 shown in Fig. 1 is attached to a smartphone 5, it is desirable that it can be used without any problems for various purposes using the contactless IC card reader 6 built into the smartphone 5. The NFC standard specifies how to read multiple cards of the same type when there are multiple cards of the same type, such as Type A MyFair Card, Type B Japanese driver's licenses, and Type F FeliCa cards. When multiple cards of different types exist, for example, if an attempt is made to read a MyFair Card and a FeliCa Card simultaneously with an iPhone contactless IC card reader, the MyFair Card will be read and the FeliCa Card will not be read.

[0034] Typically, the contactless IC card reader can specify the type of NFC card to be read and perform the reading. If the contactless IC card reader is set to read only Type F, the FeliCa card can be read even if a MyFair card and a FeliCa card are held up at the same time. However, the type of card to be read is determined by the application software installed on the smartphone. Therefore, for example, if a MyFair chip is installed on the authentication circuit board 1, it may not be possible to properly read a FeliCa card with the smartphone 5 or use the contactless IC card reader 6 installed on the smartphone 5 as a Mobile FeliCa card for payment.

[0035] If it is absolutely necessary to mount a MiFair chip on the authentication circuit board 1, a control circuit 3 that controls the operation timing can be added to the authentication circuit board 1. For example, after the first coil 4 receives power from the contactless IC card reader 6, the first NFC chip 2 can be activated for a short time (e.g., 0.3 seconds) sufficient for authentication, and then the operation of the first NFC chip 2 can be stopped, thereby enabling reading and writing of other types of NFC chips. The control circuit 3 that performs such control can be realized with a simple microcomputer. It is technically easy to design an NFC chip that incorporates the functions of the control circuit 3 into the first NFC chip 2. Therefore, when mass-producing the authentication circuit board 1, the operation timing can be controlled within the first NFC chip.

[0036] However, it is not easy to verify operation with all application software, including those used overseas. Furthermore, when using the contactless IC card reader 6 for electronic money payments, it is not easy to verify operation with all electronic money reading devices, including those used overseas. Of course, if the authentication circuit board 1 is attached to the smartphone 5 via a smartphone case, problems can be avoided by removing the smartphone case.

[0037] In a FeliCa chip, it is possible to use a system code to selectively read and write multiple FeliCa cards. In this case, a FeliCa chip assigned a unique system code can be used as the first NFC chip 2. This makes it possible to avoid interference with reading and writing of different types of MyFare cards, etc., without using a control circuit 3 that controls operation timing. Furthermore, there is no interference with reading and writing of FeliCa cards or Mobile FeliCa cards assigned a system code for electronic money.

[0038] The present inventors verified the operation of an iPhone manufactured by Apple Inc. in the United States in combination with an NFC card with a fingerprint authentication function designed for security purposes. During this verification, they attempted NFC connections by changing various application software parameters on the iPhone, but unfortunately found that the built-in contactless IC card reader could not be set to a continuous power supply state and was therefore unusable. However, the present inventors discovered that when an authentication circuit board 1 of the type shown in FIG. 1 is attached to an iPhone in the configuration shown in FIG. 1, once the contactless IC card reader 6 recognizes the first NFC chip 2 mounted on the authentication circuit board 1, the power supply timing can be controlled according to the application software parameters, and the device can also be set to a continuous power supply state. In other words, an iPhone equipped with the authentication circuit board 1 can be used for fingerprint authentication using an NFC card with a fingerprint authentication function designed for security purposes.

[0039] Figure 4 is a block diagram of a fingerprint authentication system included in an embodiment of the present invention. Elements that are the same as those shown in Figure 1 are assigned the same reference numerals. In the figure, reference numeral 8 is an NFC card with a fingerprint authentication function. Reference numeral 9 is a thin, capacitive fingerprint sensor. Reference numeral 10 is a fingerprint authentication unit. Reference numeral 11 is a memory that stores fingerprint data for verification. Reference numeral 12 is a second coil that receives power from a contactless IC card reader. Reference numeral 13 is a second NFC chip with an NFC communication function, typically a FeliCa chip. Reference numeral 14 is a user's finger whose fingerprint has been registered.

[0040] 4 , in the illustrated fingerprint authentication system, a fingerprint authentication means Fp is configured by devices mounted on an NFC card 8 with a fingerprint authentication function, namely, a fingerprint sensor 9, a fingerprint authentication unit 10, a memory 11 that stores fingerprint data for matching, a second coil 12, and a second NFC chip 13. In the fingerprint authentication means Fp, on the condition that power is supplied to the second coil 12 from a non-contact IC card reader 6 built into the smartphone 5, the powered second coil 12 supplies power to the fingerprint sensor 9, the fingerprint authentication unit 10, the memory 11, etc., and fingerprint authentication is then started. At this time, the fingerprint authentication unit 10 controls the second NFC chip 13 so that the second NFC chip 13 does not operate, for example, by stopping power supply to the second NFC chip 13.

[0041] After fingerprint authentication begins, when a finger 14 whose fingerprint has been registered in advance touches the fingerprint sensor 9, the fingerprint authentication unit 10 compares the fingerprint data of the finger 14 read from the fingerprint sensor 9 with the comparison fingerprint data stored in the memory 11. If the comparison identifies the same fingerprint, the fingerprint authentication unit 10 controls the second NFC chip 13 to operate. This enables the contactless IC card reader 6 to read the IDm2 data from the second NFC chip 13. This state is maintained until power supply to the second coil 12 is stopped.

[0042] On the other hand, before fingerprint authentication or when the fingerprint is not authenticated as the same, the fingerprint authentication unit 10 controls the second NFC chip 13 not to operate, and a state in which the IDm2 data cannot be read is maintained. By the above-mentioned control, the IDm2 data in the second NFC chip 13 can be read by the contactless IC card reader 6 only when the fingerprint is authenticated as the same. In other words, when the fingerprint is not authenticated as the same, the IDm2 data in the second NFC chip 13 cannot be read by the contactless IC card reader 6.

[0043] The IDm data is a unique ID number recorded when the FeliCa chip is manufactured. The IDm data cannot be rewritten. Therefore, no other FeliCa chip has the same IDm data. The smartphone 5 is configured to recognize that "fingerprint authentication with the NFC card 8 with fingerprint authentication function was successful" only when two conditions are met: first, the IDm2 data in the second NFC chip 13 can be read by the contactless IC card reader 6; and second, the IDm2 data pre-registered in the smartphone 5 matches the IDm2 data in the second NFC chip 13. In this case, the smartphone 5 performs authentication using two factors: the fingerprint and the FeliCa IDm data, providing higher security than simple fingerprint authentication.

[0044] 4, a FeliCa chip is used as the NFC chip that performs NFC communication with the contactless IC card reader 6. For example, since the contactless IC card reader 6 supports wireless communication according to the NFC standard, an NFC chip according to another NFC standard, such as MyFair, may be used as long as it is an NFC chip that can perform NFC communication.

[0045] In the fingerprint authentication system shown in Fig. 4, when the fingerprint authentication unit 10 has "authenticated the same fingerprint," it notifies the non-contact IC card reader 6 by making the IDm2 data readable. As a variation, other data or a combination of IDm and other data may be made readable. Various methods have been proposed and put into practical use as authentication methods for this notification, and the method can be selected taking into consideration the required level of security.

[0046] The notification method can also be realized by performing the following process. That is, when the fingerprint authentication unit 10 authenticates the same fingerprint simply by sending a predetermined command from the contactless IC card reader 6, the second NFC chip 13 transmits predetermined data, and the contactless IC card reader 6 receives this data, thereby realizing the notification method. However, even if the fingerprint authentication unit 10 does not authenticate the same fingerprint, it can be authenticated as "authenticated as the same fingerprint" by sending the same data as the predetermined data to the contactless IC card reader 6 by some other means. There is a risk of security being breached by misuse of this. It is necessary to be careful of this misuse.

[0047] Regarding this misuse, for example, when another NFC card with fingerprint authentication function on which a different fingerprint is registered is linked to the smartphone 5, it is preferable to have unique data on the NFC card with fingerprint authentication function in order to prevent the smartphone 5 from operating as if the fingerprint has been authenticated. It is also preferable to adopt a countermeasure such as making it a prerequisite for successful fingerprint authentication that this unique data matches the data registered on the smartphone 5.

[0048] In the fingerprint authentication system shown in Fig. 4, the notification method is realized by transmitting IDm2 data from the second NFC chip 13. As mentioned above, there is no FeliCa chip with the same IDm data, so it is difficult to breach security without performing fingerprint authentication as described above. In other words, it is practically difficult to breach security by using some means to make the smartphone 5 recognize that "the fingerprint has been authenticated as the same."

[0049] IDm is used for authentication in general security cards, and no major problems have arisen to date. However, some argue that IDm can be forged because its communication method and other details are disclosed. Another problem with general FeliCa cards is that IDm data can easily be read by skimming. The fingerprint authentication system shown in Figure 4 controls IDm2 data so that it can only be read if the fingerprint authentication unit 10 in the NFC card 8 with fingerprint authentication function authenticates the same fingerprint. This makes skimming impossible on the NFC card 8 with fingerprint authentication function unless it is authenticated as the same fingerprint. This significantly reduces the risk of skimming.

[0050] As a countermeasure against IDm counterfeiting of FeliCa cards, methods have been proposed, such as MAC authentication using a secret key for FeliCa Lite-S chips and using a secure area for FeliCa Standard chips. These methods can be applied as appropriate to the notification method of the fingerprint authentication system shown in Figure 4.

[0051] An example of a control method in which the smartphone 5 controls the electronic circuit built into the NFC card 8 with fingerprint authentication function in the fingerprint authentication system shown in FIG. 4 will be described with reference to the flowchart shown in FIG.

[0052] When the application software installed on the smartphone 5 is started, in the first step S1, a message "Please touch the fingerprint sensor" is displayed on the display of the smartphone 5 shown in Fig. 4, and an internal timer is started (S2). In this software, a command to turn on polling is sent to the contactless IC card reader 6 (S3), and the contactless IC card reader 6 starts polling and supplies power to the first coil 4 and the second coil 12.

[0053] The second coil 12 that has received power supplies power to the fingerprint sensor 9, fingerprint authentication unit 10, memory 11, etc. This starts fingerprint authentication. In the next step S4, the software proceeds to step S5 until the timer has counted down to 10 seconds, and proceeds to step S9 if 10 seconds have elapsed.

[0054] In step S5, this software sends a command to read the IDm data to the contactless IC card reader 6. The contactless IC card reader 6 replies to this software indicating whether reading the IDm data was successful or unsuccessful. If reading the IDm data fails, or if the IDm data read in the next step S6 matches the IDm1 data of the first NFC chip 2, the process returns to step S3 and polling is repeated.

[0055] An important thing to note when polling is repeated is that the fingerprint authentication unit 10 requires 0.5 to 2 seconds of calculation time to complete fingerprint authentication. During this loop, the second coil 12 must always be able to receive power continuously. For this reason, it is necessary to set the time for supplying power with one polling command to the non-contact IC card reader 6 to a certain length using command parameters, etc., so that the second coil 12 can always receive power continuously.

[0056] In step S6, if the read IDm data does not match the IDm1 data of the first NFC chip 2, the process proceeds to step S7. The IDm2 data of the second NFC chip 13 can be read by the contactless IC card reader 6 only if the fingerprint authentication unit 10 has authenticated the same fingerprint. Therefore, if the IDm data read in step S7 matches the IDm2 data previously registered in the smartphone 5, the system in the smartphone 5 is notified that "fingerprint authentication was successful using the NFC card 8 with fingerprint authentication function" (S8).

[0057] On the other hand, if the IDm data do not match in step S7, it is assumed that the contactless IC card reader 6 has read the IDm data of another FeliCa card. As a result, the system in the smartphone 5 is notified that "fingerprint authentication failed in the NFC card 8 with fingerprint authentication function" (S9). After notifying the system of the fingerprint authentication result, polling is turned off (S10), and the application software is terminated.

[0058] When the system in the smartphone 5 recognizes that fingerprint authentication has been successful using the NFC card 8 with fingerprint authentication function, it unlocks the smartphone 5 or permits connection to a specific network. In other words, according to the fingerprint authentication system shown in Fig. 4, the NFC card 8 with fingerprint authentication function can be used as a fingerprint authentication device in the smartphone 5.

[0059] The inventors of the present application created application software that conforms to the flowchart shown in FIG. 5 and is compatible with Apple's iPhone, and verified its actual operation. Recent iPhones have a built-in contactless IC card reader. The application software was created using CoreNFC, an NFC-standard communication framework, to be compatible with iOS 13 and later operating systems. The inventors then verified the operation of NFC-standard cards, such as common FeliCa cards, and NFC cards with fingerprint authentication functionality, using the contactless IC card reader built into the iPhone.

[0060] It was confirmed that the IDm and UID of NFC standard cards such as general FeliCa cards and MyFair cards could be read without any problems. During reading, it was possible to set the device to a continuous power supply state using command parameters, etc. However, it was discovered that continuous power supply was not possible when simply combining an NFC card with fingerprint authentication function with an iPhone, and fingerprint authentication and IDm reading were also not possible.

[0061] FIG. 6 shows the power supply state to the second coil 12 when the iPhone application software is launched based on the flowchart shown in FIG. 5 in the fingerprint authentication system shown in FIG. 4 with the authentication circuit board 1 removed, i.e., with only the combination of the NFC card 8 with fingerprint authentication function and the iPhone (smartphone 5). FIG. 6 is a timing chart for a first example. After examining the aforementioned problem of inability to supply continuous power, the inventors of the present application discovered that the cause was the short period of time for each polling command set by the initial setting. Even when attempting to address this issue by changing the time slot value of parameters such as the CoreNFC Polling command to extend the period for each polling, the actual power supply period remained unchanged. For this reason, as shown in FIG. 6, power is supplied to the second coil 12 for a short period of time repeatedly at regular intervals. Therefore, it was found that application software alone cannot achieve a continuous power supply state for the fingerprint authentication system shown in FIG. 4 to operate on an iPhone.

[0062] When an NFC-compliant card, such as a standard FeliCa card or MyFair card, is held close to the contactless IC card reader 6 built into the iPhone, i.e., when NFC communication is actually taking place, the change in the time slot value is effective, the power supply period is adjustable, and continuous power supply is possible. However, when the authentication circuit board 1 is removed from the fingerprint authentication system shown in FIG. 4, the second NFC chip 13 is only able to communicate via NFC after fingerprint authentication is successful. Furthermore, fingerprint authentication is not complete unless continuous power supply is achieved. Therefore, the change in the time slot value cannot be effective, and continuous power supply is not possible.

[0063] With this application software running, when the authentication circuit board 1 is brought close to the built-in contactless IC card reader 6, the first NFC chip 2 is recognized, the change in the time slot value becomes effective, the actual polling period becomes longer, and a state in which continuous power supply is possible. By entering a continuous power supply state, the fingerprint authentication system shown in Figure 4 becomes capable of fingerprint authentication, and it was confirmed that after fingerprint authentication is successful, the second NFC chip 13 enters a state in which it can operate.

[0064] However, when the first NFC chip 2 of the authentication circuit board 1 that is brought close to the contactless IC card reader 6 in order to change the timeSlot value is a MiFair chip, even after successful fingerprint authentication in the fingerprint authentication system shown in Fig. 4, the contactless IC card reader 6 reads the UID, which is the unique data of the first NFC chip 2, and is unable to read the IDm data of the second NFC chip 13. The inventors of the present application believe that this is because the built-in contactless IC card reader 6 first performs NFC communication with the MiFair chip and then tries to maintain communication with the MiFair chip, preventing communication with the second NFC chip 13.

[0065] To solve this problem, it is necessary to make the non-contact IC card reader 6 in FIG. 4 enter a continuous power supply state by having the NFC chip recognized after power supply to the second coil 12 starts so that the change in the timeSlot value becomes effective, and also to make it possible for the non-contact IC card reader 6 to actually read the IDm of the second NFC chip 13 in a continuous power supply state.

[0066] Furthermore, in recent years, contactless IC card readers 6 of smartphones are required not only to read cards but also to perform NFC communication with various external devices for electronic money payments, etc. When the authentication circuit board 1 included in the fingerprint authentication system shown in Fig. 4 is attached to a smartphone 5, and the contactless IC card reader 6 performs NFC communication with another IC card using other application software, or when performing NFC communication with various external devices including an external contactless IC card reader, the embodiment of the present invention must be usable without interference.

[0067] According to the NFC communication standard, the communication sequence between a contactless IC card reader and an NFC chip consists of, first, an "initial response" that establishes a communication path between the contactless IC card reader and the target NFC chip, and, second, an "active state" that exchanges information according to the application.

[0068] First, when power supply from the contactless IC card reader begins in an initial response, the NFC chip enters a state of waiting for a communication path establishment request (request command) from the contactless IC card reader. Next, the contactless IC card reader sends a request command, and the NFC chip returns a response. This recognizes an NFC chip present in the communication area of ​​the contactless IC card reader. The contactless IC card reader then exchanges parameters with the recognized NFC chip, and mutually confirms conditions such as communication speed. After this, the contactless IC card reader transitions from the initial response to the active state. In the active state, the NFC chip recognized in the initial response is selected, and NFC communication is performed by repeatedly receiving responses from the NFC chip in response to commands from the contactless IC card reader.

[0069] There are various types of NFC chips, such as Type A MyFair chips, Type B MyFair chips used in Japanese driver's licenses, and Type F FeliCa chips. Each type of chip has its own processing method for when multiple NFC chips of the same type are present simultaneously in the initial response. When multiple NFC types of chips are present, only the NFC chips of the specified type can be recognized by specifying the type of NFC chip to be read. When multiple types are specified, multiple specified types of cards can be recognized. However, there are limitations not specified in the NFC communication standards, such as when a MyFair card and a FeliCa card are recognized simultaneously, the UID of the MyFair card is read with priority over the IDm of the FeliCa card.

[0070] Type A NFC chips such as the MiFair chip (i) use a method called the bit collision method to read the UIDs of all recognized MiFair chips when multiple MiFair chips are recognized during the initial response, then (ii) the contactless IC card reader designates one of the read UIDs, and (iii) the MiFair chip with the matching UID responds, thereby selecting one from the multiple MiFair chips. Therefore, MiFair chips that do not respond during the initial response cannot be recognized.

[0071] When multiple FeliCa chips are present, if the IDm is known, the IDm can be specified and the FeliCa chip with the matching IDm will respond. Alternatively, if the system codes of the multiple FeliCa chips are different, it is possible to specify the system code and read the IDm data of the corresponding FeliCa chip even if the chips are stacked. In order to change the time slot value during the initial response, if the FeliCa chip recognized by the contactless IC card reader 6 is changed to one with a different system code from the second NFC chip 13 included in the fingerprint authentication system shown in Figure 4, even if the FeliCa chip recognized during the initial response remains in an operating state after successful fingerprint authentication, it was confirmed that the built-in contactless IC card reader 6 can read the IDm data of the second NFC chip 13 by specifying the system code of the second NFC chip 13. Since the FeliCa chip that initially responded had a different system code from the second NFC chip 13, its IDm could not be read, but it was confirmed that it entered a continuous power supply state.

[0072] In the contactless IC card reader 6 built into the iPhone, if any NFC chip is recognized in the initial response, the change in the timeSlot value becomes effective. However, in order to maintain a continuous power supply state and, after fingerprint authentication is successful, to enable the second NFC chip 13 in the NFC card 8 with fingerprint authentication function to notify the contactless IC card reader 6 that fingerprint authentication has been successful, it is necessary to skillfully combine the control timing and type of the NFC chip recognized in the initial response and the type of the second NFC chip 13 in the NFC card 8 with fingerprint authentication function.

[0073] FIG. 7 shows the power supply state to the second coil 12 when starting up the iPhone application software based on the flowchart shown in FIG. 5 in the fingerprint authentication system shown in FIG. 4 . FIG. 7 is a timing chart of a second example. Referring to FIG. 7 , when power is supplied to the second coil 12 to validate the change in the time slot value, power is simultaneously supplied to the first coil 4 in the authentication circuit board 1. A short time after the start of power supply, the first NFC chip 2 is enabled for a short period of time by the control circuit 3. As a result, an initial response for NFC communication is made between the built-in contactless IC card reader 6 and the first NFC chip 2 within the initial short polling period, and the change in the time slot value becomes valid. Therefore, the actual polling period is lengthened, resulting in a continuous power supply state. Even if the operation of the first NFC chip 2 is stopped after the continuous power supply state is established, the continuous power supply state is maintained for a certain period of time.

[0074] 7 , the first NFC chip 2 is activated by the control circuit 3 a little while after power is supplied to the second coil 12, but they may be activated simultaneously. The delay time is provided to delay the order of recognition so that the first NFC chip 2 does not interfere with the following cases: (i) when application software other than this software is launched to read an NFC card with the contactless IC card reader 6, or (ii) when the contactless IC card reader 6 built into the smartphone 5 performs NFC communication with an external device for electronic money payment, etc.

[0075] Since fingerprint authentication by an NFC card 8 with fingerprint authentication function takes at least 0.5 to 1 second, if the first NFC chip 2 is made operational by starting power supply and then stopped in about 0.3 seconds, the first NFC chip 2 and the second NFC chip 13 will not be in an operational state at the same time, and there will be no problem even if different types of NFC chips are combined.

[0076] Furthermore, if the first NFC chip 2 and the second NFC chip 13 are both FeliCa chips, once the FeliCa chip is recognized in the initial response, NFC communication is possible after transitioning to the active state not only when the system codes of the two FeliCa chips are different, but also when there is only one FeliCa chip operating simultaneously, even if the system code of the first NFC chip 2 is the same as the system code of the second NFC chip 13. Therefore, even if two low-cost FeliCa Lite-S chips are used, operation can be performed without problems as long as the two NFC chips are controlled not to operate simultaneously.

[0077] The FeliCa Lite-S chip has a different system code than the FeliCa Standard chip used for electronic money, etc. Therefore, it will not interfere with NFC communication between the contactless IC card reader 6 built into the smartphone 5 and an external device for electronic money payments, etc.

[0078] In the fingerprint authentication system shown in FIG. 4, the state of power supply to the second coil 12 when iPhone application software based on the flowchart shown in FIG. 5 is started is shown in FIG. 8. FIG. 8 is a timing chart of a third example. Note that in the timing chart of the third example, the control circuit 3 shown in FIG. 4 is omitted, and the operating state of the first NFC chip 2 is determined only by the state of power supply to the first coil 4. Referring to FIG. 8, when power is supplied to the second coil 12 to validate the change in the time slot value, power is also supplied to the first coil 4 in the authentication circuit board 1 at the same time. This puts the first NFC chip 2 into an operable state and maintains the operable state until power supply is stopped.

[0079] 8, after successful fingerprint authentication, not only the second NFC chip 13 but also the first NFC chip 2 remain in an operable state at the same time. In this state, it is necessary to select the type of NFC chip that can read IDm2 of the second NFC chip 13 that has not sent an initial response.

[0080] As mentioned above, if one Felica chip responds at the time of initial response, multiple Felica chips can be read. To read multiple Felica chips, the corresponding Felica chips will respond by specifying IDm or by specifying a system code. However, CoreNFC does not have a way to specify IDm. Therefore, it is necessary to specify a system code and read the corresponding Felica chip. In this case, if multiple system codes are specified, the corresponding Felica chips can be read simultaneously.

[0081] If there are multiple FeliCa chips with the same system code, they cannot be read simultaneously, so the first NFC chip 2 should have a FeliCa chip with a system code different from that of the second NFC chip 13. Here, in order to avoid interfering with communication with FeliCa chips with specific system codes when making electronic money payments on an iPhone, it is better to select a FeliCa chip with a system code different from those system codes as the first NFC chip 2.

[0082] As described above, according to the embodiment described based on the timing charts shown in FIGS. 6 , 7 , and 8 , even in a smartphone such as an iPhone that cannot continuously supply power from the contactless IC card reader 6 built into the smartphone 5 using only its original application software, (i) the authentication circuit board 1 is attached to the smartphone 5, (ii) the first NFC chip 2 in the authentication circuit board 1 is recognized in the initial response, thereby enabling continuous power supply, (iii) the fingerprint authentication unit 10 in the NFC card 8 with fingerprint authentication function starts fingerprint authentication upon receiving power supply from the contactless IC card reader 6 built into the smartphone 5, and (iv) if the fingerprint authentication is successful, the contactless IC card reader 6 receives a fingerprint authentication notification from the second NFC chip 13 in the NFC card 8 with fingerprint authentication function, thereby notifying the smartphone 5 that “the fingerprint has been authenticated as the same.”

[0083] Furthermore, if the first NFC chip 2 recognized in the initial response is a FeliCa chip, by appropriately selecting the system code, it is possible to prevent the embodiment of the present invention from interfering in cases such as (i) when application software other than this application software is launched and an NFC card is read using a contactless IC card reader 6, or (ii) when a contactless IC card reader 6 built into a smartphone 5 performs NFC communication with an external device for electronic money payments, etc.

[0084] In Figures 7 and 8, for smartphones such as iPhones, which cannot normally maintain continuous power supply from the built-in contactless IC card reader using application software alone, the application software can achieve continuous power supply by having the NFC chip recognized in the initial response.

[0085] 9 and 10 are cross-sectional views for explaining the fingerprint authentication system of Fig. 4. In Fig. 9 and 10, the same elements as those shown in Fig. 4 are given the same reference numerals. Reference numeral 15 shown in Fig. 9 and 10 denotes a smartphone case that is attached to the smartphone 5. Reference numeral 16 denotes an LED. The LED 16 is mounted on the NFC card 8 with fingerprint authentication function. The LED 16 constitutes a display unit that displays the power supply status of the NFC card with fingerprint authentication function, the success or failure of fingerprint authentication, etc.

[0086] 9 and 10 , the authentication circuit board 1 can be partially bent by partially or entirely using a flexible printed circuit board or the like, as shown in FIG. 1 . The authentication circuit board 1 is disposed behind the display of the smartphone 5, and the bent portion covers a portion of the side of the smartphone 5 with the authentication circuit board 1. This allows the magnetic flux of the alternating magnetic field generated by the non-contact IC card reader 6 to pass through the first coil 4 in the authentication circuit board 1. As a result, the authentication circuit board 1 can operate with wireless power supply from the non-contact IC card reader 6. The authentication circuit board 1 is fixed to the smartphone case 15 with double-sided tape or the like. While the authentication circuit board 1 may be fixed directly to the smartphone 5 with double-sided tape or the like, it is preferable to fix it so that it can be easily attached and detached from the smartphone 5 for maintenance purposes such as repairs. Furthermore, by separating the authentication circuit board 1 from the smartphone 5 by the thickness of the case, the effective area of ​​the first coil 4, through which the alternating magnetic field from the non-contact IC card reader 6 passes, can be increased. This allows the authentication circuit board 1 to receive a more stable power supply.

[0087] Referring to FIG. 9 , the authentication circuit board 1 is attached to the smartphone 5 via the smartphone case 15, and the NFC card 8 with fingerprint authentication function is accessed near the contactless IC card reader 6. When power supply from the contactless IC card reader 6 begins in this state, the first NFC chip 2 in the authentication circuit board 1 is activated, and the first NFC chip 2 is recognized by the contactless IC card reader 6 as an initial response. As a result, power is continuously supplied to the NFC card 8 with fingerprint authentication function, enabling fingerprint authentication. In FIG. 9 , we verified the operation of the authentication circuit board 1 by bending FeliCa cards of different sizes, stickers with equivalent functions, and flexible printed circuit modules. We found that a larger area for the first coil 4 located along the back of the display of the smartphone 5 broadens the range over which sufficient power can be supplied to the NFC card 8 with fingerprint authentication function for operation. These verification results confirmed that the range of relative positions between the contactless IC card reader 6 and the NFC card 8 with fingerprint authentication function is expanded. In other words, it was confirmed that power can be supplied from the non-contact IC card reader 6 to a wider range via the first coil 4.

[0088] Referring to FIG. 10 , in the illustrated embodiment, a mechanism for holding an NFC card 8 with fingerprint authentication function is added to the smartphone case 15. By adding this card holding mechanism to the smartphone case 15, the NFC card 8 with fingerprint authentication function can be stored in the smartphone case 15 when not in use. To perform fingerprint authentication, the NFC card 8 with fingerprint authentication function is removed from the smartphone case 15 and fingerprint authentication is performed in the state shown in FIG. 10 . In both cases shown in FIGS. 9 and 10 , the fingerprint sensor 9 is located on the display side of the smartphone 5, allowing the user to touch the fingerprint sensor 9 with their finger 14 while visually confirming the position of the fingerprint sensor 9. This ensures reliable fingerprint authentication. Furthermore, the LED 16 on the NFC card 8 with fingerprint authentication function allows the user to check the power supply status, the success or failure of fingerprint authentication, and other information while performing fingerprint authentication. The use shown in FIG. 10 can also be achieved by attaching a commercially available card holder for holding credit card-sized cards to the smartphone case 15 shown in FIG. 9 .

[0089] 9 and 10, by using multiple NFC cards 8 with fingerprint authentication function, it is possible to perform fingerprint authentication with separate cards for corporate and personal use, thereby achieving higher security. Also, with one NFC card 8 with fingerprint authentication function, it is possible to use the fingerprint authentication function not only with the smartphone 5 but also with other devices, thereby increasing convenience.

[0090] The fingerprint authentication systems shown in Figures 4, 9, and 10 can provide usability equivalent to that of a fingerprint authentication device built into a smartphone. Furthermore, they can ensure security against attacks such as SIM swap attacks, in which a criminal registers his or her biometric information on a new smartphone to which the criminal has transferred his or her phone number, thereby disabling the smartphone's built-in facial authentication and fingerprint authentication. In other words, a SIM swap attack alone cannot allow a criminal to obtain an NFC card 8 with a fingerprint authentication function that has a registered fingerprint. Even if a criminal obtains a new NFC card 8 with a fingerprint authentication function that has no registered fingerprint and registers his or her own fingerprint, the unique data in the NFC card 8 with a fingerprint authentication function will be different, so fingerprint authentication will not be recognized as successful in a SIM swap attack. Even if a criminal obtains an NFC card 8 with a registered fingerprint and registers his or her own fingerprint, fingerprint authentication will not be successful with the criminal's fingerprint. Thus, the fingerprint authentication system of the present invention can be said to be a fingerprint authentication device that is effective against SIM swap attacks. The fingerprint authentication system of the present invention can provide higher security than fingerprint authentication devices built into smartphones.

[0091] The authentication circuit board 1 shown in Figures 1, 4, 9, and 10 is attached to a smartphone 5 to enable continuous power supply, even for models such as the iPhone, which cannot achieve continuous power supply from the built-in contactless IC card reader using application software alone. Furthermore, when the authentication circuit board 1 is attached, the first NFC chip 2 of the authentication circuit board 1 can be accessed at any time from the smartphone 5 to confirm unique numbers such as IDm1, making it usable as a form of multi-factor authentication. Because authentication using the authentication circuit board 1 is not fingerprint authentication, it is ineffective against SIM swap attacks if the authentication circuit board 1 is stolen. However, if the authentication circuit board 1 is not stolen, it serves as an effective authentication device against SIM swap attacks. Since touching the fingerprint sensor is not required, authentication using an NFC card 8 with fingerprint authentication function is required for large remittances in online banking, while authentication using the authentication circuit board 1 can be used for logging in to online banking and checking balances, ensuring smooth operation.

[0092] As mentioned above, the authentication circuit board 1 does not have a fingerprint authentication function, so if the authentication circuit board 1 is stolen, it is basically ineffective against SIM swap attacks. However, by adding an electronic circuit for an NFC card 8 with fingerprint authentication function to the authentication circuit board 1 and configuring it as a single circuit board, it becomes possible to prevent SIM swap attacks even in the event of theft. Note that when configuring it as a single circuit board, it is easy for those skilled in the art to design a circuit board in which a single coil serves as both the first coil 4 and the second coil 12.

[0093] REFERENCE SIGNS LIST 1 authentication circuit board 2 first NFC chip 3 control circuit 4 first coil 5 smartphone 6 contactless IC card reader 7 FeliCa card, etc. 8 NFC card with fingerprint authentication function Fp fingerprint authentication means 9 fingerprint sensor 10 fingerprint authentication unit 11 memory 12 second coil 13 second NFC chip 15 smartphone case 16 LED

Claims

1. An external authentication circuit board for a smartphone that is attached to a smartphone with a built-in contactless IC card reader and allows the smartphone to be operated while attached, comprising: a first NFC chip that has the function of communicating with the contactless IC card reader via NFC; and a first coil that receives power from the contactless IC card reader, wherein a portion of the first coil covers a portion of the side of the smartphone so that the magnetic flux of the alternating magnetic field generated by the contactless IC card reader passes through the first coil, thereby enabling the first NFC chip to supply the power necessary for NFC communication with the contactless IC card reader, thereby allowing the authentication circuit board to be used on the smartphone as one of the multi-factor authentication means.

2. The external authentication circuit board for a smartphone as described in claim 1, further comprising a control circuit that controls the operation timing of the first NFC chip, wherein the control circuit renders the first NFC chip operable when the first coil receives power, and stops the operation of the first NFC chip after a sufficient amount of time has elapsed for it to be used as one of the multi-factor authentication means, thereby not preventing the contactless IC card reader from communicating with other NFC chips via NFC.

3. The external authentication circuit board for a smartphone according to claim 1, wherein the first NFC chip is a FeliCa chip.

4. The external authentication circuit board for a smartphone according to claim 1, characterized in that the authentication circuit board is attached to the smartphone via a smartphone case.

5. The external authentication circuit board for a smartphone according to claim 2, characterized in that the authentication circuit board is attached to the smartphone via a smartphone case.

6. The external authentication circuit board for a smartphone according to claim 3, characterized in that the authentication circuit board is attached to the smartphone via a smartphone case.

7. The authentication circuit board has a function of adding authentication by fingerprint authentication in addition to the multi-factor authentication means by enabling an NFC card with a fingerprint authentication function to be used with the smartphone, and the NFC card with fingerprint authentication function is equipped with fingerprint authentication means including a fingerprint sensor, a fingerprint authentication unit, a memory for storing fingerprint data for comparison, a second coil for receiving power from the non-contact IC card reader, and a second NFC chip having a function of NFC communication with the non-contact IC card reader, the fingerprint authentication means has a built-in fingerprint authentication function including a fingerprint data reading function for starting to read fingerprint data using the fingerprint sensor when the second coil receives power from the non-contact IC card reader, a fingerprint data matching function for matching the read fingerprint data with the fingerprint data for comparison stored in the memory by the fingerprint authentication unit, and a fingerprint authentication notification function for performing the NFC communication from the second NFC chip to the non-contact IC card reader and notifying the non-contact IC card reader that the fingerprints have been authenticated as the same only when the fingerprint authentication unit recognizes the same fingerprint; The external authentication circuit board for a smartphone according to any one of claims 1 to 6, characterized in that: the fingerprint sensor, the fingerprint authentication unit, the memory, and the second NFC chip operate only with the power received by the second coil; the smartphone is a model in which continuous power supply from the contactless IC card reader to the second coil cannot be performed by application software installed on the smartphone alone; when power is received from the contactless IC card reader by the first coil, the first NFC chip is recognized in an initial response to the NFC communication, thereby continuously supplying power from the contactless IC card reader to the second coil; the fingerprint authentication is completed by the fingerprint authentication unit; and if the fingerprint authentication is successful, a fingerprint authentication notification is sent.

8. The external authentication circuit board for a smartphone as described in claim 7, characterized in that the fingerprint authentication notification, which notifies that fingerprint authentication has been successful when the fingerprint authentication unit recognizes the same fingerprint, is data using unique data stored in the second NFC chip and transmitted to the contactless IC card reader via NFC communication.

9. The external authentication circuit board for a smartphone as described in claim 8, characterized in that the smartphone compares data using the unique data transmitted from the second NFC chip to the contactless IC card reader via NFC communication with data pre-registered in the smartphone, and when the data match, the smartphone recognizes that the fingerprints have been authenticated as the same fingerprint by the fingerprint authentication unit.

10. The external authentication circuit board for a smartphone according to claim 7, characterized in that the fingerprint authentication function is implemented on the same board as the authentication circuit board.

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