Biometric authentication system

Abstract

A wearable device (1) comprises: an amplification unit (101) that differentially amplifies a biometric signal detected by an electrode (100) and a biometric signal transmitted from an authentication device (2) through human body communication; and a transmission unit (102) that transmits an output signal of the amplification unit (101) to the authentication device (2) through human body communication. The authentication device (2) comprises: an amplification unit (202) [GW1.1]that differentially amplifies a biometric signal detected by an electrode (200) and the biometric signal transmitted from the device (1) through human body communication; a transmission unit (202) that transmits an output signal of the amplification unit (202) to the device (1) through human body communication; and an authentication unit (22) that performs user authentication on the basis of the output signal of the amplification unit (201).

Description

Biometric authentication system

[0001] The present invention relates to a biometric authentication system.

[0002] The human body serves as a good communication medium for wireless signals. For this reason, methods for performing wireless communication through the human body have been studied (Non-Patent Document 1). According to the method disclosed in Non-Patent Document 1, power consumption can be reduced compared to general wireless methods in which wireless signals propagate through space. Also, information transmission is possible when people touch each other.

[0003] As a system using human body communication, a system that transmits user authentication information by human body communication and performs user authentication can be considered. In the technology disclosed in Non-Patent Document 1, an electric field is applied to a part of the human body surface, and human body communication is performed by detecting the electric field induced in a part of the human body different from this part. In an authentication system using human body communication, authentication is performed by a receiver at the propagation destination of the authentication information.

[0004] However, signals used for human body communication propagate if they are dielectrics. For this reason, there is a possibility that signals propagate via dielectrics other than the human body or between multiple human bodies, and communication may be established unintentionally. In an authentication system using human body communication, authentication by human body communication may be performed unintentionally, and there was a possibility that security could not be ensured.

[0005] Ai-ichiro Sasaki, et al., “Modeling of Human-body Near-field Communication and Evaluation of Communication Quality”, NTT Technical Review, Vol.8, No.3, pp.1-6, Mar.2010

[0006] The present invention has been made to solve the above problems, and an object thereof is to realize a system with high security in a biometric authentication system using human body communication.

[0007] The biometric authentication system of the present invention comprises a wearable device that acquires a user's biometric signal, and an authentication device that acquires the user's biometric signal and performs user authentication. The wearable device includes a first electrode provided at a position where the user touches the wearable device, a first receiving unit that receives a biometric signal transmitted from the authentication device by human body communication that occurs when the user touches the wearable device and the authentication device, a first amplification unit that differentially amplifies the biometric signal detected by the first electrode and the biometric signal received by the first receiving unit, and the biometric signal output from the first amplification unit is transmitted by human body communication. The authentication device comprises a first transmitting unit that transmits a signal to the authentication device, the authentication device being characterized by comprising a second electrode provided at a position where the user touches the authentication device, a second receiving unit that receives a biosignal transmitted from the wearable device by the human body communication, a second amplification unit that differentially amplifies the biosignal detected by the second electrode and the biosignal received by the second receiving unit, a second transmitting unit that transmits the biosignal output from the second amplification unit to the wearable device by the human body communication, and a first authentication unit that performs user authentication based on the biosignal output from the second amplification unit.

[0008] According to the present invention, biometric signal measurement is only possible when the user is touching the wearable device and the authentication device. Therefore, if communication is mistakenly established through another person or object, the biometric signal cannot be measured and user authentication will not be successful. As a result, the present invention can realize a highly secure biometric authentication system.

[0009] Figure 1 is a block diagram showing the configuration of a biometric authentication system according to the first embodiment of the present invention. Figures 2A and 2B show specific examples of the biometric authentication system according to the first embodiment of the present invention. Figure 3 is a block diagram showing another configuration of the biometric authentication system according to the first embodiment of the present invention. Figure 4 is an external view of an authentication device according to the second embodiment of the present invention. Figure 5 is an external view of an authentication device according to the third embodiment of the present invention. Figures 6A and 6C show a biometric authentication system according to the fifth embodiment of the present invention. Figure 7 is a block diagram showing the configuration of a biometric authentication system according to the sixth embodiment of the present invention. Figure 8 is a block diagram showing the configuration of a biometric authentication system according to the seventh embodiment of the present invention. Figure 9 is an external view of an authentication device according to the seventh embodiment of the present invention. Figure 10 is a diagram illustrating a fingerprint detection method. Figure 11 is a diagram illustrating another fingerprint detection method. Figure 12 is a block diagram showing another configuration of a biometric authentication system according to the seventh embodiment of the present invention.

[0010] [Principle of the Invention] Conventional electrocardiographs measure the potential difference between two different points on the human body using two or more electrodes. In this invention, the device is divided into two parts, one as a wearable device and the other as an authentication device. Normally, dividing the device would make it impossible to measure the electrocardiogram waveform. In this invention, the electrocardiogram (biosignal) obtained from electrodes provided on the wearable device and the authentication device is transmitted to the other device via human body communication, thereby achieving the same functionality as a normal electrocardiograph. As a result, biosignal measurement is only established when the user is touching the authentication device, and user authentication is performed based on the characteristic quantities of that biosignal. In the event that communication is mistakenly established with a person or object other than the user in between, the biosignal cannot be measured and authentication will not be established, creating a secure state.

[0011] [First Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a block diagram showing the configuration of a biometric authentication system according to the first embodiment of the present invention. The biometric authentication system consists of a wearable device 1 that acquires the user's biometric signals and an authentication device 2 that acquires the user's biometric signals and performs user authentication. Figure 13 shows the user's body.

[0012] The wearable device 1 includes a biosignal measurement unit 10. The biosignal measurement unit 10 consists of electrodes 100 provided at a position where the user touches the wearable device 1, a receiving unit 103 that receives biosignals transmitted from the authentication device 2 via human body communication that occurs when the user touches the wearable device 1 and the authentication device 2, an amplification unit 101 that differentially amplifies the biosignals detected by the electrodes 100 and the biosignals received by the receiving unit 103, and a transmitting unit 102 that transmits the biosignals output from the amplification unit 101 to the authentication device 2 via human body communication.

[0013] The authentication device 2 comprises a biosignal measurement unit 20, an AD conversion unit 21 that converts the biosignal acquired by the biosignal measurement unit 20 into a digital signal, an authentication unit 22 that performs user authentication based on the biosignal output from the AD conversion unit 21, a communication unit 23 for communication with the outside, a CPU (Central Processing Unit) 24, and a storage device 25.

[0014] The biosignal measurement unit 20 consists of an electrode 200 provided at a position where the user touches the authentication device 2, a receiving unit 203 that receives biosignals transmitted from the wearable device 1 via human body communication, an amplification unit 201 that differentially amplifies the biosignals detected by the electrode 200 and the biosignals received by the receiving unit 203, and a transmitting unit 202 that transmits the biosignals output from the amplification unit 201 to the wearable device 1 via human body communication.

[0015] The transmitter 102 of the wearable device 1 modulates the carrier wave according to the output signal of the amplifier 101 and transmits the modulated signal. The modulated signal is transmitted from the electrode 100 through the user's body 3 to the authentication device 2. The receiver 203 of the authentication device 2 demodulates the modulated signal transmitted from the wearable device 1 and received by the electrode 200, and inputs the extracted biosignal to the amplifier 201.

[0016] The transmitting unit 202 of the authentication device 2 modulates the carrier wave according to the output signal of the amplification unit 201 and transmits the modulated signal. The modulated signal is transmitted from the electrode 200 through the user's body 3 to the wearable device 1. The receiving unit 103 of the wearable device 1 demodulates the modulated signal received by the electrode 100 and inputs the extracted signal to the amplification unit 101.

[0017] The amplification unit 101 of the wearable device 1 amplifies the difference between the biosignal detected by the electrode 100 and the biosignal input from the receiving unit 103. The amplification unit 201 of the authentication device 2 amplifies the difference between the biosignal detected by the electrode 200 and the biosignal input from the receiving unit 203.

[0018] In this embodiment, when a user wearing the wearable device 1 on their body touches the authentication device 2, the authentication device 2 can acquire the user's biometric signals. Therefore, even if a communication leak occurs, authentication will not be successful unless the user touches the authentication device 2, thus maintaining security. The user does not need to enter a password or anything similar. Thus, this embodiment can achieve both convenience and high security for the user.

[0019] The specific operation of this embodiment will be explained using an electrocardiogram waveform as an example of a biosignal. The user puts on the wearable device 1 and touches the electrodes 200 of the authentication device 2. This establishes a communication path between the wearable device 1 and the authentication device 2 via the user's body 3.

[0020] The wearable device 1 and the authentication device 2 each acquire weak electrocardiograms of 1 mV or less from electrodes 100 and 200 for biosignal detection. The amplifier unit 101 of the wearable device 1 differentially amplifies the electrocardiogram acquired from electrode 100 and the electrocardiogram received from the authentication device 2. The amplifier unit 201 of the authentication device 2 differentially amplifies the electrocardiogram acquired from electrode 200 and the electrocardiogram received from the wearable device 1. For the amplifier units 101 and 201, it is preferable to use operational amplifier circuits, which are common in instrumentation amplifiers.

[0021] A circuit system capable of mutual signal exchange is constructed by transmitting electrocardiogram (ECG) signals acquired by the wearable device 1 to the authentication device 2, and transmitting ECG signals acquired by the authentication device 2 to the wearable device 1. This allows the function of a differential amplifier circuit to be realized without connecting the wearable device 1 and the authentication device 2 with ground lines or signal lines. The human body is a dielectric and is particularly suitable for signal transmission up to about 100 MHz. Therefore, by performing frequency division in the frequency range of 100 MHz or less, bidirectional signal transmission can be performed simultaneously between the wearable device 1 and the authentication device 2. In other words, the frequency (carrier frequency) of the modulated signal transmitted by the transmitter 102 of the wearable device 1 and the frequency of the modulated signal transmitted by the transmitter 202 of the authentication device 2 should be different.

[0022] In this embodiment, the authentication device 2 includes an AD conversion unit 21, a CPU 24, a communication unit 23, etc., but it does not necessarily have to include all of these. In the example in Figure 1, the authentication unit 22 is shown outside the CPU 24, but the CPU 24 may also implement the functions of the authentication unit 22. Alternatively, the authentication unit 22 may be provided on an external server device.

[0023] Wearable device 1 can take any form, such as a wristwatch, wristband, ankle band, clothing, or necklace. Alternatively, wearable device 1 may be attached to the user's body.

[0024] Authentication device 2 can take the form of PC (Personal Computer) related equipment such as a mouse or keyboard, or a mobile terminal such as a smartphone. Alternatively, various devices used for user authentication in homes, offices, medical institutions, and transportation facilities may also be considered authentication device 2.

[0025] Figures 2A and 2B show specific examples of this embodiment. Figure 2A shows a state in which a user is wearing a wristwatch-type wearable device 1 on their right arm 3a and touching the electrode 200 of the authentication device 2 with their left hand 3b. In Figure 2A, V1 represents the signal transmitted from the wearable device 1 to the authentication device 2, and V2 represents the signal transmitted from the authentication device 2 to the wearable device 1. As shown in Figure 2B, an electrode 100 is provided on the side of the wearable device 1 that is on the user's body.

[0026] As explained above, when the user touches the authentication device 2, signals are sent and received between the wearable device 1 and the authentication device 2, and the biosignal is amplified. In this embodiment, electrocardiograms and electromyograms can be acquired as biosignals, but electrocardiograms are particularly suitable for biometric authentication. Examples of biometric authentication features using electrocardiograms include (I) and (II) below, but the present invention is not limited to these, and any information obtained from electrocardiograms is acceptable.

[0027] (I) PQ interval, QRS interval, QT interval, ST interval, P wave amplitude, Q wave amplitude, R wave amplitude, S wave amplitude, T wave amplitude, angle from Q wave to R wave, angle from Q wave to S wave, angle from R wave to S wave, angle from S wave to T wave, area of ​​P wave, area of ​​Q wave, area of ​​R wave, area of ​​S wave, area of ​​T wave. (II) Frequency distribution of part of the electrocardiogram waveform or the entire electrocardiogram waveform, phase coefficient between the electrocardiogram waveform and the electrocardiogram waveform of the previous beat, wavelet coefficient of the electrocardiogram waveform.

[0028] Multiple elements from (I) and (II) may be extracted as features. In the case of (I), the statistical values ​​of the data obtained multiple times may be used as features. The authentication unit 22 of the authentication device 2 extracts features from the biometric signal output from the AD conversion unit 21 and performs user authentication by comparing the features with verification data. For this reason, the storage device 25 has features of the user's biometric signal acquired in advance registered as verification data. Alternatively, machine learning of the model may be performed using features of multiple users acquired in advance. In this case, the authentication unit 22 obtains a user authentication result (success or failure) by inputting the features extracted from the biometric signal into the trained model.

[0029] When acquiring verification data, the waveform shape obtained changes depending on the approximate position of the electrodes that acquire the electrocardiogram. Therefore, it is desirable to measure the electrocardiogram waveforms of multiple users by adjusting the wearing position of the wearable device 1 and the part of the user's body that touches the authentication device 2 to match the actual usage situation. Furthermore, convenience is enhanced by measuring data with different wearing positions of the wearable device 1 and the parts of the user's body that touch the authentication device 2.

[0030] Human biosignals can change over time. Therefore, instead of always using pre-acquired verification data, the authentication unit 22 may update the verification data using the characteristic features of the user's biosignals at the time of successful authentication. This can reduce authentication errors.

[0031] In the example shown in Figure 1, the authentication unit 22 is located within the authentication device 2, but it may also be located in an external server device. The configuration in this case is shown in Figure 3. The communication unit 23 of the authentication device 2 transmits the biometric signal output from the AD conversion unit 21 to the server device 4. The authentication device 2 and the server device 4 are connected via a network 5.

[0032] The communication unit 41 of the server device 4 receives the biometric signal transmitted from the authentication device 2. The authentication unit 40 of the server device 4 performs user authentication based on the biometric signal received by the communication unit 41, similar to the authentication unit 22. The communication unit 41 transmits the user authentication result to the authentication device 2. The communication unit 23 of the authentication device 2 receives the user authentication result. In this way, the same operation as when the authentication unit 22 is located within the authentication device 2 can be achieved.

[0033] [Second Embodiment] Figure 4 shows an example in which a mouse 6, a PC-related device, is used as the authentication device 2 of the first embodiment. By providing electrodes 200 on the upper surface of the mouse 6, good contact with the user's body can be expected. When the user touches the mouse 6 to operate the PC, the mouse 6 measures biosignals and performs user authentication. If authentication is successful, the user can operate the PC. According to this embodiment, the user does not need to enter a password. Furthermore, even if a communication leak occurs, authentication will not be established unless the user is touching the mouse 6, thus ensuring security.

[0034] [Third Embodiment] Figure 5 shows an example in which a mobile terminal 7, such as a smartphone, is used as the authentication device 2 of the first embodiment. The mobile terminal 7 can also be made to function as an authentication device 2 by providing electrodes 200 on the sides or back that the user touches. In particular, by providing electrodes 200 in areas that the user naturally touches when using the mobile terminal 7, it becomes possible to eliminate the need for fingerprint authentication of the mobile terminal 7 or facial authentication using a mask, glasses, or sunglasses.

[0035] [Fourth Embodiment] If the wearable device 1 is a necklace-type device, biosignals can be measured regardless of which hand the user touches the authentication device 2 with. By making the wearable device 1 a necklace shape, electrodes 100 are positioned on the user's neck and upper chest. Therefore, regardless of whether the user touches the electrodes 200 of the authentication device 2 with their left or right hand, the electrodes 100 and 200 that acquire biosignals are sufficiently far apart, making it possible to acquire biosignals well.

[0036] Furthermore, the present invention is also effective when an implantable device embedded in the user's body is used instead of the wearable device 1. Electrical signals penetrate to some extent not only on the body surface but also into the inside of the human body. Therefore, it is possible to perform user authentication by measuring biosignals with the implantable device and the authentication device 2, respectively, and by sending and receiving signals to and from each other. This allows the user to easily undergo authentication without being aware of wearing a device.

[0037] [Fifth Embodiment] Figure 6A shows an example where the smart key 8 of the automobile is the wearable device 1 of the first embodiment. In this embodiment, the user's automobile functions as the authentication device 2. The smart key system can be unlocked simply by the user bringing the smart key 8 close to the automobile. In this embodiment, for example, electrodes 100 are provided on the side or back of the smart key 8. Also, as shown in Figure 6B, electrodes 200 are provided on the door handle 90 on the outside of the automobile door 9. When a user possessing the smart key 8 touches the automobile door handle 90, the automobile, which is the authentication device 2, performs user authentication, and if authentication is successful, unlocks the door 9. Alternatively, the automobile may be configured to automatically start the engine if authentication is successful.

[0038] Alternatively, as shown in Figure 6C, an electrode 200 may be provided on the door handle 91 on the inside of the door 9. In this case, when a user possessing the smart key 8 touches the door handle 91, the car, which is the authentication device 2, performs user authentication, and if authentication is successful, starts the engine.

[0039] Conventional smart key systems achieve simple unlocking by continuously emitting weak radio waves from the smart key. However, there is a risk of unauthorized unlocking by intercepting the radio waves emitted by the smart key. In this embodiment, human body communication, which emits little external radiation and is difficult to intercept, is used, and user authentication is performed when the user carrying the wearable device 1 touches the door handles 90, 91. This eliminates the unauthorized use of radio waves and dramatically improves security.

[0040] Alternatively, electrodes 200 may be provided on the steering wheel of the automobile. In this case, when a user possessing the smart key 8 touches the steering wheel, the automobile, which is the authentication device 2, performs user authentication, and if authentication is successful, starts the engine. In this way, by ensuring that only pre-registered users can drive the vehicle, theft and unauthorized use of the automobile can be prevented.

[0041] In the first to fifth embodiments, continuous authentication may be performed while the user is touching the electrode 200. By providing the electrode 200 at a portion that the user continuously touches when using some device, multiple authentications can be performed during use. Thereby, it is possible to limit the use of the device by someone else replacing the user after authentication, and enhance security. For example, in the second embodiment, by providing the electrode 200 on the mouse 6, repeated authentication can be performed based on the biological signal continuously measured while the user is operating the PC.

[0042] Continuous authentication may be performed at any interval, such as at intervals of several seconds or several minutes. However, when measuring the user's electrocardiogram waveform as the biological signal, considering the heart rate of about 60 bpm on average at rest, it is desirable to perform authentication at an interval of at least 1 second or more. The human heart rate can be as low as about 30 bpm. Therefore, when it is necessary to perform authentication reliably and frequently for users with a low heart rate, authentication may be performed at an interval of 2 seconds or more.

[0043] [Sixth Embodiment] By using the information of the wearable device as device information in combination with the biological signal, multi-factor authentication can be realized. In order to measure the biological signal, it is necessary not only for the user to touch the electrode 200 of the authentication device 2 but also for the user to possess or wear the wearable device on the body. Therefore, the information unique to the wearable device can be used as device information.

[0044] FIG. 7 is a block diagram showing the configuration of the biometric authentication system according to the sixth embodiment of the present invention. The wearable device 1a is obtained by adding a communication unit 11 for communication with the authentication device 2a to the wearable device 1 of the first to fifth embodiments. The authentication device 2a is obtained by adding a communication unit 26 for communication with the wearable device 1a to the authentication device 2 of the first to fifth embodiments.

[0045] The communication unit 11 of the wearable device 1a wirelessly transmits, for example, an identification number unique to the wearable device 1a as device information to the authentication device 2a. The communication unit 26 of the authentication device 2a receives the device information transmitted from the wearable device 1a.

[0046] The authentication unit 22a of the authentication device 2a performs authentication based on the user's biological signal in the same manner as the authentication unit 22 in the first to fifth embodiments, and at the same time performs device authentication by collating the received device information with the verification device information. For this reason, information of the wearable device 1a is registered in advance in the storage device 25 as verification device information. When the authentication unit 22a succeeds in authentication based on the user's biological signal and the received device information matches the verification device information and device authentication is successful, it determines that user authentication is successful. When at least one of the authentication based on the biological signal and the authentication based on the device information fails, the authentication unit 22a determines that user authentication fails.

[0047] In this embodiment, even if only the measurement circuit of the biological signal is replicated, authentication based on the device information does not hold, and the security can be enhanced. The communication unit 11 may encrypt and transmit the device information, and the communication unit 26 may decrypt the data transmitted from the communication unit 11 and extract the device information.

[0048] Also, in order to prevent communication eavesdropping, the device information may be hashed using a challenge & response method or the like. In this case, the authentication device 2a wirelessly transmits data (challenge) generated from a random number to the wearable device 1a. The wearable device 1a generates a hash value from the received data and its own device information and wirelessly transmits it to the authentication device 2a. The authentication unit 22a of the authentication device 2a generates a hash value from the data (challenge) transmitted to the wearable device 1a and the verification device information registered in advance, and if the generated hash value matches the hash value received from the wearable device 1a, it determines that device authentication is successful.

[0049] As in the third embodiment, when a mobile device 7 such as a smartphone is used as the authentication device 2, the mobile device 7 has locking functions such as password lock, fingerprint authentication, and facial recognition, so an even stronger authentication function can be achieved.

[0050] In this embodiment, if authentication based on the user's biometric signals and authentication based on device information are successful, the wearable device 1a that the user possesses or wears on their body can also be used as an authenticated device. For example, in an environment where only authorized users are allowed to enter, authentication is required each time one enters to move or work. A person who has accessed the premises illegally by some means will be denied entry through authentication each time, but even legitimate users face the inconvenience of having to undergo authentication each time they enter. Therefore, by using the wearable device 1a as an authenticated device, authentication can be skipped, thus resolving this inconvenience issue.

[0051] Specifically, when the communication unit 26 of the authentication device 2a successfully authenticates a device, it wirelessly transmits authenticated certification information to the wearable device 1a, the source of the device information. The communication unit 11 of the wearable device 1a acquires the authenticated certification information transmitted from the authentication device 2a. The transmission unit 102 of the wearable device 1a not only modulates the carrier wave according to the biosignal output from the amplification unit 101 and transmits the modulated signal, but also modulates the carrier wave according to the authenticated certification information and transmits the modulated signal. At this time, it is sufficient to ensure that the frequency of the modulated signal modulated by the biosignal and the frequency of the modulated signal modulated by the authenticated certification information are different.

[0052] The receiving unit 203 of the authentication device 2a demodulates the modulated signal transmitted from the wearable device 1a and received by the electrode 200, and extracts the biosignal and authenticated certification information. The receiving unit 203 is equipped with a filter circuit. The receiving unit 203 separates the modulated signal modulated by the biosignal and the modulated signal modulated by the authenticated certification information, so that only the biosignal obtained by demodulation is input to the amplification unit 201. The authentication unit 22a of the authentication device 2a determines that authentication is successful even if the user's biosignal cannot be obtained, as long as authenticated certification information can be obtained. This makes it possible to substitute for biometric authentication.

[0053] The wearable device 1a can communicate with the authentication device 2a capacitively via the user's clothing or shoes, even when the user cannot directly touch the authentication device 2a. Therefore, the authentication device 2a can be operated even when the user is wearing gloves or carrying luggage and cannot directly touch the authentication device 2a. Within a controlled area, security is maintained as authentication does not occur through an unspecified number of people.

[0054] Furthermore, the present invention is also effective in ensuring the authenticity of the user. The present invention measures biosignals at two points: the body part of the user in contact with the wearable device 1,1a and the body part of the user in contact with the authentication device 2,2a. When an unauthorized user wears the wearable device 1,1a, and a legitimate user touches the authentication device 2,2a and then touches the unauthorized user's body, human body communication is established between the authentication device 2,2a and the wearable device 1,1a via the legitimate user's body. However, in this case, the signal output from the amplification unit 201 of the authentication device 2,2a is the difference between the biosignal of the unauthorized user and the biosignal of the legitimate user. Therefore, authentication will not be successful.

[0055] In this embodiment, the communication unit 11 of the wearable device 1a transmits device information to the authentication device 2a via wireless communication using space as the transmission path. However, it may also transmit the information to the authentication device 2a via human body communication. In this case, the communication unit 11 modulates the carrier wave according to the device information and transmits the modulated signal to the authentication device 2a via the electrode 100 and the user's body 3. When using human body communication, it is desirable to set the frequency (carrier wave frequency) of the modulated signal transmitted by the transmitter unit 102 of the wearable device 1a, the frequency of the modulated signal transmitted by the communication unit 11, and the frequency of the modulated signal transmitted by the transmitter unit 102 of the authentication device 2a to be different values ​​from each other.

[0056] The receiving unit 203 of the authentication device 2a demodulates the modulated signal transmitted from the wearable device 1a and received by the electrode 200 to extract the biosignal. The receiving unit 203 is equipped with a filter circuit. The receiving unit 203 separates the modulated signal modulated by the biosignal from the modulated signal modulated by the device information, so that only the biosignal extracted from the modulated signal modulated by the biosignal is input to the amplification unit 201. The communication unit 26 of the authentication device 2a also demodulates the modulated signal transmitted from the wearable device 1a and received by the electrode 200 to extract the device information. The communication unit 26 is equipped with a filter circuit. The communication unit 26 separates the modulated signal modulated by the biosignal from the modulated signal modulated by the device information, and demodulates the modulated signal modulated by the device information.

[0057] [Seventh Embodiment] The biometric authentication system of the present invention may have other biometric authentication functions. Figure 8 is a block diagram showing the configuration of the biometric authentication system according to the seventh embodiment of the present invention. The authentication device 2b is the authentication device 2 of the first to fifth embodiments with the addition of a fingerprint authentication unit 27. The authentication unit 22b of the authentication device 2b determines that user authentication is successful when it has succeeded in authentication based on the user's biometric signal and the fingerprint authentication unit 27 has succeeded in authenticating the user's fingerprint.

[0058] Figure 9 shows an example where a mobile device 7, such as a smartphone, is used as the authentication device 2b in this embodiment. In Figure 9, 70 indicates the display panel of the mobile device 7, and 71 indicates the fingerprint recognition area on the display panel 70. According to the configuration in Figure 9, multimodal biometric authentication combining biosignal-based authentication and fingerprint authentication can be realized in a compact form. Methods for detecting the user's fingerprint include optical and ultrasonic methods.

[0059] As shown in Figure 10, the optical method obtains fingerprint information by receiving reflected light from the user's finger 3c touching the recognition area 71 with the light receiving sensor 270 of the fingerprint authentication unit 27. As shown in Figure 11, the ultrasonic method obtains fingerprint information by emitting ultrasonic waves from the transducer 271 of the fingerprint authentication unit 27 to the user's finger 3c touching the recognition area 71 and receiving the reflected waves from the finger 3c with the transducer 271.

[0060] By placing a transparent electrode in the recognition area 71 and using the transparent electrode as the electrode 200 of the authentication device 2b, authentication based on the user's biometric signals can be performed simultaneously with fingerprint authentication, enabling multimodal biometric authentication without impairing the display on the mobile terminal 7. Materials for the transparent electrode include indium tin oxide and graphene.

[0061] The fingerprint authentication unit 27 may also be applied to the sixth embodiment. The configuration in this case is shown in Figure 12. In the configuration of Figure 12, the authentication unit 22c of the authentication device 2c determines that user authentication is successful if it succeeds in authentication based on the user's biometric signal, device authentication, and fingerprint authentication. The authentication unit 22c determines that user authentication is unsuccessful if at least one of the biometric signal authentication, device authentication, and fingerprint authentication fails.

[0062] In the examples of Figures 1, 7, 8, and 12, the authentication units 22, 22a to 22c and the fingerprint authentication unit 27 are shown outside the CPU 24. However, the authentication units 22, 22a to 22c and the fingerprint authentication unit 27 can be realized by a computer consisting of a CPU 24 and a storage device 25, and a program that controls these hardware resources. In such a computer, the program for realizing the method of the present invention is stored in the storage device 25. The CPU 24 executes the processes described in the first to seventh embodiments according to the program stored in the storage device 25.

[0063] Some or all of the above examples may also be described as follows, but are not limited to the following:

[0064] (Note 1) The biometric authentication system of the present invention comprises a wearable device that acquires a user's biometric signal, and an authentication device that acquires a user's biometric signal and performs user authentication, wherein the wearable device includes a first electrode provided at a position where the user touches the wearable device, a first receiving unit that receives a biometric signal transmitted from the authentication device by human body communication that occurs when the user touches the wearable device and the authentication device, a first amplification unit that differentially amplifies the biometric signal detected by the first electrode and the biometric signal received by the first receiving unit, and the biometric signal output from the first amplification unit The authentication device comprises a first transmitting unit that transmits a body signal to the authentication device via human body communication, the authentication device comprising a second electrode provided at a position where the user touches the authentication device, a second receiving unit that receives a biosignal transmitted from the wearable device via human body communication, a second amplification unit that differentially amplifies the biosignal detected by the second electrode and the biosignal received by the second receiving unit, a second transmitting unit that transmits the biosignal output from the second amplification unit to the wearable device via human body communication, and a first authentication unit that performs user authentication based on the biosignal output from the second amplification unit.

[0065] (Note 2) In the biometric authentication system described in Note 1, the wearable device further comprises a first communication unit that transmits device information unique to the device to the authentication device via communication using space as a transmission path or via human body communication, the authentication device further comprises a second communication unit that receives the device information, and the first authentication unit performs user authentication based on the authentication result based on the biometric signal output from the second amplification unit and the authentication result based on the device information received by the second receiving unit.

[0066] (Note 3) In the biometric authentication system described in Note 1, the first authentication unit repeatedly performs user authentication based on continuously acquired biometric signals.

[0067] (Note 4) In the biometric authentication system described in Note 1, the authentication device further comprises a second authentication unit that performs user authentication based on the user's biometric information different from the biometric signal, and the first authentication unit performs user authentication based on the authentication result based on the biometric signal output from the second amplification unit and the authentication result by the second authentication unit.

[0068] 1, 1a... Wearable device, 2, 2a to 2c... Authentication device, 4... Server device, 5... Network, 6... Mouse, 7... Mobile terminal, 8... Smart key, 9... Door, 10, 20... Biosignal measurement unit, 11, 23, 26, 41... Communication unit, 21... AD conversion unit, 22, 22a to 22c, 40... Authentication unit, 24... CPU, 25... Storage device, 27... Fingerprint authentication unit, 100, 200... Electrodes, 101, 201... Amplification unit, 102, 202... Transmitter, 103, 203... Receiver.

Claims

1. A wearable device that acquires a user's biosignal, and an authentication device that acquires a user's biosignal and performs user authentication, wherein the wearable device includes a first electrode provided at a position where the user touches the wearable device, a first receiving unit that receives a biosignal transmitted from the authentication device by human body communication that occurs when the user touches the wearable device and the authentication device, a first amplifying unit that differentially amplifies the biosignal detected by the first electrode and the biosignal received by the first receiving unit, and a first transmitting unit that transmits the biosignal output from the first amplifying unit to the authentication device by human body communication, wherein the authentication device includes a second electrode provided at a position where the user touches the authentication device, a second receiving unit that receives a biosignal transmitted from the wearable device by human body communication, and a second amplifying unit that differentially amplifies the biosignal detected by the second electrode and the biosignal received by the second receiving unit, A biometric authentication system comprising: a second transmitting unit that transmits a biometric signal output from the second amplification unit to the wearable device via human body communication; and a first authentication unit that performs user authentication based on the biometric signal output from the second amplification unit.

2. The biometric authentication system according to claim 1, wherein the wearable device further comprises a first communication unit that transmits device information unique to the device to the authentication device by communication using space as a transmission path or by human body communication, the authentication device further comprises a second communication unit that receives the device information, and the first authentication unit performs user authentication based on an authentication result based on a biometric signal output from the second amplification unit and an authentication result based on device information received by the second receiving unit.

3. A biometric authentication system according to claim 1, characterized in that the first authentication unit repeatedly performs user authentication based on continuously acquired biometric signals.

4. The biometric authentication system according to claim 1, wherein the authentication device further comprises a second authentication unit that performs user authentication based on the user's biometric information different from the biometric signal, and the first authentication unit performs user authentication based on the authentication result based on the biometric signal output from the second amplification unit and the authentication result by the second authentication unit.

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