Smart entry system, central device, smart entry program, and smart entry method

Abstract

This smart entry system comprises: a central device; and peripheral devices that transmit radio waves to the central device. The central device includes: a communication unit that receives the radio waves; a measurement unit that measures values relating to the radio waves; and a determination unit that, on the basis of a plurality of types of measurement results by the measurement unit and a determination standard based on the distribution of previously acquired measurement results, assesses validity of the radio waves and determines permission for entry on the basis of the assessment result.

Description

[Technical field]

[0001] The present disclosure relates to a smart entry system, a central device, a smart entry program, and a smart entry method. This application claims priority based on Japanese Patent Application No. 2020-205465, filed on December 11, 2020, the disclosure of which is incorporated herein in its entirety. [Background technology]

[0002] Patent Document 1 (Japanese Patent No. 6653986) discloses the following relay attack determination device. That is, the relay attack determination device is a relay attack determination device that determines a relay attack in which wireless communication between an in-vehicle device and a portable device is relayed by a repeater, and includes a transmitter provided in the in-vehicle device and that transmits a first signal and a second signal having output conditions different from those of the first signal, a receiver provided in the portable device and that receives the first signal and the second signal, an intensity measurement unit provided in the portable device and that measures the reception intensity of each of the first signal and the second signal received by the receiver multiple times, and a signal strength measurement unit that measures the reception intensity of each of the first signal and the second signal received by the receiver multiple times. a comparison unit that performs a comparison process of the first signal and the second signal using the average value of the reception strength measured by a reception strength measurement unit; a judgment unit that judges the relay attack based on the result of the comparison process; and a variation calculation unit that calculates the variation of the reception strength measured multiple times by the strength measurement unit for the signal with low reception strength among the first signal and the second signal, wherein the judgment unit judges the relay attack regardless of the result of the comparison process when the variation of the reception strength exceeds a threshold value indicating a communication abnormality.

[0003] Moreover, Patent Document 2 (Japanese Patent No. 6653985) discloses the following relay attack determination device. That is, the relay attack determination device is a relay attack determination device that determines a relay attack in which wireless communication between an in-vehicle unit and a portable unit is relayed by a repeater, and includes a transmitting unit provided in the in-vehicle unit that transmits a first signal and a second signal having output conditions different from those of the first signal, a receiving unit provided in the portable unit that has multiple axis antennas each facing in a different direction and receives the first signal and the second signal on each of the multiple axes, a strength measuring unit provided in the portable unit that measures the receiving strength on each of the multiple axes for the first signal and the second signal received by the receiving unit, a comparison unit that performs a comparison process of the receiving strength ratio of the first signal and the second signal based on the measured value of the receiving strength, and a determination unit that determines a relay attack based on the result of the comparison process of the comparison unit, and if there is an invalid axis among the multiple axes where the measured value of the receiving strength of the first signal or the second signal falls outside the usable range, the comparison unit performs the comparison process by excluding the invalid axis.

[0004] Also, Patent Document 3 (JP Patent Publication No. 2020-521073) discloses a BLE (Bluetooth Low Energy) passive vehicle access control system as follows. That is, the BLE passive vehicle access control system includes a vehicle, an external device communicatively coupled to the vehicle, a position receiver assembly configured to identify coordinates of at least one of the vehicle and the external device, and a processor communicatively coupled to the position receiver assembly, which disables communication between the vehicle and the external device when the coordinates of the vehicle and the coordinates of the external device do not match. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6653986 [Patent Document 2] Patent No. 6653985 [Patent Document 3] Special Publication No. 2020-521073 Summary of the Invention

[0006] The smart entry system of the present disclosure comprises a central device and a peripheral device that transmits radio waves to the central device, and the central device includes a communication unit that receives the radio waves transmitted from the peripheral device, a measurement unit that measures values ​​related to the radio waves, and a judgment unit that evaluates the legitimacy of the radio waves based on multiple types of measurement results by the measurement unit and judgment criteria based on the distribution of each of the measurement results obtained in advance, and judges whether to allow entry based on the evaluation result.

[0007] The central device of the present disclosure includes a communication unit that receives radio waves, a measurement unit that measures values ​​related to the radio waves, and a judgment unit that evaluates the legitimacy of the radio waves based on multiple types of measurement results by the measurement unit and judgment criteria based on the distribution of each of the measurement results obtained in advance, and judges whether to allow entry based on the evaluation results.

[0008] The smart entry program disclosed herein is a smart entry program used in a central device that receives radio waves from a peripheral device, and is a program for causing a computer to function as a measurement unit that measures values ​​related to the radio waves, and a judgment unit that evaluates the legitimacy of the radio waves based on multiple types of measurement results by the measurement unit and judgment criteria based on the distribution of each of the measurement results obtained in advance, and determines whether to allow entry based on the evaluation results.

[0009] The smart entry method disclosed herein is a smart entry method in a central device, and includes the steps of receiving radio waves from a peripheral device, measuring values ​​related to the radio waves, evaluating the legitimacy of the radio waves based on multiple types of measurement results of the radio waves and a judgment criterion based on the distribution of each of the measurement results obtained in advance, and determining whether to allow entry based on the evaluation results.

[0010] An aspect of the present disclosure may be realized as a semiconductor integrated circuit that realizes part or all of a central device, or as a system that includes a central device. Also, an aspect of the present disclosure may be realized as a semiconductor integrated circuit that realizes part or all of a system that includes a central device, or as a program that causes a computer to execute processing steps in a system that includes a central device. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a configuration of a smart entry system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing a configuration of a peripheral device in the smart entry system according to the embodiment of the present disclosure. [Diagram 3] FIG. 3 is a diagram showing a configuration of a central device in a smart entry system according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a diagram showing an example of an operation procedure when permitting entry in the smart entry system according to the embodiment of the present disclosure. [Diagram 5] FIG. 5 is a diagram showing an example of an operation procedure when permitting entry in the smart entry system according to the embodiment of the present disclosure. [Figure 6] FIG. 6 is a diagram illustrating an example of a parameter group stored in a storage unit in the smart entry system according to the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Conventionally, techniques have been developed to improve security in smart entry systems.

[0013] [Problem that this disclosure aims to solve] There is a demand for a technology that goes beyond the technologies described in Patent Documents 1 to 3 and is capable of more accurately detecting unauthorized entries, such as relay attacks, against a smart entry system.

[0014] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a smart entry system, a central device, a smart entry program, and a smart entry method that are capable of more accurately detecting fraudulent entries in a smart entry system.

[0015] [Effects of this disclosure] According to the present disclosure, fraudulent entries in a smart entry system can be detected more accurately.

[0016] [Description of the embodiments of the present disclosure] First, the contents of the embodiments of the present disclosure will be listed and described.

[0017] (1) A smart entry system according to an embodiment of the present disclosure includes a central device and a peripheral device that transmits radio waves to the central device. The central device includes a communication unit that receives the radio waves transmitted from the peripheral device, a measurement unit that measures values ​​related to the radio waves, and a judgment unit that evaluates the legitimacy of the radio waves based on multiple types of measurement results by the measurement unit and a judgment criterion based on a distribution of each of the measurement results obtained in advance, and judges whether to allow entry based on the evaluation result.

[0018] In this manner, the validity of radio waves transmitted from the peripheral device to the central device is evaluated based on a plurality of types of measurement results and a criterion based on the distribution of each measurement result obtained in advance, and entry permission is determined based on the evaluation result, thereby making it possible to improve the accuracy of the evaluation compared to when the validity of radio waves is evaluated based on a single measurement result, and also to prevent the evaluation accuracy from decreasing even when there is a change in signal strength due to, for example, the peripheral device being placed in a case, etc. Therefore, unauthorized entries in the smart entry system can be detected more accurately.

[0019] (2) The radio waves may include encrypted information, and the determination unit may be configured to evaluate the legitimacy of the radio waves further based on whether or not the encrypted information can be decrypted.

[0020] With this configuration, the method of evaluating the validity of radio waves is multiplexed, making it possible to more accurately detect fraudulent entries in the smart entry system.

[0021] (3) The smart entry system may include a plurality of the peripheral devices, and the judgment unit may be configured to evaluate the legitimacy of the radio waves transmitted from the corresponding peripheral device based on the judgment criteria for each of the peripheral devices.

[0022] With this configuration, even if there are performance differences between peripheral devices in terms of electric field strength, encryption processing speed, and the like, it is possible to prevent a decrease in evaluation accuracy.

[0023] (4) The multiple types of measurement results may include a round trip time (RTT) of the radio waves and a received signal strength indication (RSSI) of the radio waves.

[0024] With this configuration, the central device can have a simple configuration using a simple measurement system.

[0025] (5) The determination unit may be configured to evaluate the validity of the radio waves based on a Mahalanobis distance calculated from a distribution of the multiple types of measurement results by the measurement unit and the determination criterion.

[0026] With this configuration, unauthorized entries can be detected more accurately using software processing.

[0027] (6) The smart entry system may further include a locking mechanism controlled by the central device, and the determination unit may be configured to determine whether the locking mechanism is opened or closed based on the evaluation result.

[0028] Such a configuration can improve security in, for example, homes, vehicles, etc.

[0029] (7) The locking mechanism may be an electronic lock provided on a door, and the determination unit may be configured to switch between unlocking and locking the door using the locking mechanism based on the evaluation result.

[0030] Such an arrangement can improve security for doors of homes, vehicles, etc., for example.

[0031] (8) A central device according to an embodiment of the present disclosure includes a communication unit that receives radio waves, a measurement unit that measures values ​​related to the radio waves, and a judgment unit that evaluates the legitimacy of the radio waves based on multiple types of measurement results by the measurement unit and a judgment criterion based on a distribution of each of the measurement results obtained in advance, and judges whether to allow entry based on the evaluation result.

[0032] In this way, the central device evaluates the validity of the radio waves received based on multiple types of measurement results and a criterion based on the distribution of each measurement result obtained in advance, and determines whether entry is permitted based on the evaluation result. This configuration makes it possible to improve the accuracy of the evaluation compared to when the validity of the radio waves is evaluated based on a single measurement result, and also makes it possible to prevent the evaluation accuracy from decreasing even when, for example, there is a change in signal strength. Therefore, unauthorized entries in the smart entry system can be detected more accurately.

[0033] (9) A smart entry program according to an embodiment of the present disclosure is a smart entry program used in a central device that receives radio waves from a peripheral device, and is a program for causing a computer to function as a measurement unit that measures values ​​related to the radio waves and a judgment unit that evaluates the legitimacy of the radio waves based on multiple types of measurement results by the measurement unit and judgment criteria based on the distribution of each of the measurement results obtained in advance, and determines whether to allow entry based on the evaluation results.

[0034] In this manner, the validity of radio waves transmitted from the peripheral device to the central device is evaluated based on a plurality of types of measurement results and a criterion based on the distribution of each measurement result obtained in advance, and entry permission is determined based on the evaluation result, thereby making it possible to improve the accuracy of the evaluation compared to when the validity of radio waves is evaluated based on a single measurement result, and also to prevent the evaluation accuracy from decreasing even when there is a change in signal strength due to, for example, the peripheral device being placed in a case, etc. Therefore, unauthorized entries in the smart entry system can be detected more accurately.

[0035] (10) A smart entry method according to an embodiment of the present disclosure is a smart entry method in a central device, and includes the steps of receiving radio waves from a peripheral device, measuring values ​​related to the radio waves, evaluating the legitimacy of the radio waves based on multiple types of measurement results of the radio waves and a judgment criterion based on a distribution of each of the measurement results obtained in advance, and determining whether to allow entry based on the evaluation results.

[0036] In this manner, the validity of radio waves transmitted from the peripheral device to the central device is evaluated based on a plurality of types of measurement results and a criterion based on the distribution of each measurement result obtained in advance, and entry permission is determined based on the evaluation result, thereby making it possible to improve the accuracy of the evaluation compared to when the validity of radio waves is evaluated based on a single measurement result, and also to prevent the evaluation accuracy from decreasing even when there is a change in signal strength due to, for example, the peripheral device being placed in a case, etc. Therefore, unauthorized entries in the smart entry system can be detected more accurately.

[0037] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated. In addition, at least some of the embodiments described below may be arbitrarily combined.

[0038] [Configuration and basic operation] FIG. 1 is a diagram showing a configuration of a smart entry system according to an embodiment of the present disclosure.

[0039] With reference to FIG. 1, a smart entry system 1 includes a peripheral device 11, a central device 12, and a locking mechanism 13.

[0040] The peripheral device 11 is, for example, an electronic key that can be carried by the user 80 and has a wireless communication function. The peripheral device 11 transmits to the central device 12, for example, radio waves including an advertisement signal adopted in Bluetooth Low Energy (Bluetooth is a registered trademark) conforming to the IEEE802.15.1 standard.

[0041] The central device 12 includes, for example, an electronic lock, and is provided on a door 90 of the house. The central device 12 is capable of wireless communication with the peripheral device 11. The central device 12 has, for example, a scanning function, and receives radio waves transmitted from the peripheral device 11 when the peripheral device 11 enters the communication range. Note that the wireless communication between the peripheral device 11 and the central device 12 may be by a broadcast method or a connection method.

[0042] When the central device 12 receives an advertising signal from the peripheral device 11, it performs a process of connecting with the peripheral device 11. More specifically, the central device 12 transmits a scan request to the peripheral device 11 in response to the received advertising signal. When the peripheral device 11 receives the scan request, it transmits a scan response to the central device 12. This establishes a communication connection between the central device 12 and the peripheral device 11. The process of connecting between the central device 12 and the peripheral device 11 is well known, and therefore will not be described in detail.

[0043] When the central device 12 establishes a communication connection with the peripheral device 11, it evaluates whether the peripheral device 11 is authentic. If the central device 12 evaluates that the peripheral device 11 is authentic, it permits the entry of the peripheral device 11, and if it evaluates that the peripheral device 11 is not authentic, it denies the entry of the peripheral device 11. Specifically, the central device 12 permits or denies the entry of the peripheral device 11 by determining whether the lock mechanism 13 is open or closed based on the evaluation result.

[0044] The locking mechanism 13 is, for example, an electronic lock provided on the door 90, and is controlled by the central device 12. More specifically, the central device 12 switches between unlocking and locking the door 90 by the locking mechanism 13 based on the evaluation result. Specifically, when the central device 12 permits the entry of the peripheral device 11, the locking mechanism 13 unlocks or locks the door 90, and when the central device 12 denies the entry of the peripheral device 11, the locking mechanism 13 maintains the locked or unlocked state of the door 90.

[0045] FIG. 2 is a diagram showing a configuration of a peripheral device in the smart entry system according to the embodiment of the present disclosure.

[0046] With reference to FIG. 2, the peripheral device 11 includes a communication unit 111, a processing unit 112, and a storage unit 113.

[0047] The communication unit 111 receives, for example, radio waves in the LF (Low Frequency) band from the central unit 12 and transmits radio waves in the RF (Radio Frequency) band to the central unit 12. The communication unit 111 is realized by a communication circuit such as a communication IC (Integrated Circuit).

[0048] The processing unit 112 performs encryption and decryption of data. For example, the processing unit 112 performs encryption of data to be transmitted to the central device 12, and decrypts encrypted data received from the central device 12. The processing unit 112 is realized by a processor such as a CPU (Central Processor Unit) or a DSP (Digital Signal Processing). The storage unit 113 is, for example, a non-volatile memory.

[0049] FIG. 3 is a diagram showing a configuration of a central device in a smart entry system according to an embodiment of the present disclosure.

[0050] 3, the central device 12 includes a communication unit 121, a processing unit 122, an RTT measurement unit 1231, a determination unit 124, and a storage unit 125. The communication unit 121 includes an RSSI measurement unit 1232. The communication unit 121 is realized by a communication circuit such as a communication IC. The processing unit 122, the RTT measurement unit 1231, and the determination unit 124 are realized by a processor such as a CPU or a DSP. The storage unit 125 is, for example, a non-volatile memory.

[0051] The communication unit 121 performs wireless communication with the communication unit 111 in the peripheral device 11. The communication unit 121 receives radio waves in the RF band transmitted from the peripheral device 11, and transmits radio waves in the LF band to the peripheral device 11, for example.

[0052] The processing unit 122 performs data encryption and decryption, etc. For example, the processing unit 122 performs encryption of data to be transmitted to the peripheral device 11, and decrypts encrypted data received from the peripheral device 11.

[0053] The RTT measurement unit 1231 and the RSSI measurement unit 1232, which are examples of measurement units, measure values ​​related to radio waves transmitted from the peripheral device 11. More specifically, the RTT measurement unit 1231 measures an RTT (Round Trip Time) in wireless communication between the central device 12 and the peripheral device 11. The RSSI measurement unit 1232 measures an RSSI (Received Signal Strength Indicator) of the radio waves transmitted from the peripheral device 11.

[0054] The determination unit 124 evaluates the validity of the peripheral device 11 and determines whether or not to permit the entry of the peripheral device 11.

[0055] [Operation flow] Each device in the smart entry system according to the embodiment of the present disclosure includes a computer including a memory, and a processor such as a CPU in the computer reads out from the memory and executes a program including some or all of the steps of the following sequence. Each of the programs for the multiple devices can be installed from the outside. Each of the programs for the multiple devices is distributed in a state stored in a recording medium or via a communication line.

[0056] Figures 4 and 5 are diagrams showing an example of an operation procedure when permitting entry in the smart entry system according to the embodiment of the present disclosure. Figure 4 shows the first half of the operation procedure, and Figure 5 shows the second half of the operation procedure. Note that Figures 4 and 5 show the operation procedure after the connection process between the peripheral device 11 and the central device 12 is completed.

[0057] 4, first, when the connection process between the central device 12 and the peripheral device 11 is completed, the user 80 selects the calibration mode or the evaluation mode in the central device 12. In the calibration mode, a calibration process is performed for various parameters used when evaluating the validity of the radio waves from the peripheral device 11. In the evaluation mode, the validity of the radio waves is evaluated, and permission for entry is determined based on the evaluation result. The user 80 operates, for example, a switch or the like provided in the central device 12 to select the mode (step S101).

[0058] Next, in the central device 12, the processing unit 122 creates an encryption key. More specifically, the processing unit 122 creates, for example, a pair of a public key and a private key. The processing unit 122 also creates a digital certificate for the created public key (step S102).

[0059] Next, the processing unit 122 transmits the created public key and electronic certificate together with a key exchange request to the peripheral device 11 via the communication unit 121 (step S103).

[0060] Furthermore, in the peripheral device 11, the processing unit 112 creates an encryption key when the connection process between the central device 12 and the peripheral device 11 is completed. More specifically, the processing unit 112 creates, for example, a pair of a public key and a private key. The processing unit 112 also creates a digital certificate for the created public key (step S104).

[0061] Next, processing unit 112 checks whether or not a key exchange request has been received from central device 12 via communication unit 111. More specifically, if processing unit 112 has not received a key exchange request (NO in step S105), it waits for a key exchange request from central device 12. On the other hand, if processing unit 112 receives a public key, electronic certificate, and key exchange request from central device 12 via communication unit 111 (YES in step S105), it verifies the electronic certificate.

[0062] Next, when the processing unit 112 confirms that the received public key was not created by the central device 12 (NO in step S106), it terminates the communication connection with the central device 12 (step S107). On the other hand, when the processing unit 112 confirms that the received public key was created by the central device 12 (YES in step S106), it transmits the created public key and electronic certificate together with a key exchange response to the central device 12 via the communication unit 111 (step S108), and creates a common key using the created private key and the received public key (step S109).

[0063] Furthermore, in central device 12, processing unit 122 checks whether or not a key exchange response has been received from peripheral device 11 via communication unit 121. More specifically, processing unit 122 waits for the key exchange response (NO in step S110), and upon receiving a public key, a digital certificate, and the key exchange response from peripheral device 11 via communication unit 121 (YES in step S110), verifies the digital certificate.

[0064] Next, if the processing unit 122 confirms that the received public key was not created in the peripheral device 11 (NO in step S111), it rejects the entry of the peripheral device 11 (step S112). On the other hand, if the processing unit 122 confirms that the received public key was created in the peripheral device 11 (YES in step S111), it creates a common key using the created private key and the received public key (step S113).

[0065] 5, next, processing unit 122 encrypts data using the created common key. The data is, for example, a signal (hereinafter referred to as a heartbeat) that peripheral device 11 periodically transmits to confirm that it is in an active state (step S114).

[0066] Next, the processing unit 122 periodically transmits the encrypted heartbeat to the peripheral device 11 via the communication unit 121, and stores the transmission time of the heartbeat in the storage unit 125 (step S115).

[0067] Next, in the peripheral device 11, the processing unit 112 checks whether or not a heartbeat has been received from the central device 12 via the communication unit 111. More specifically, the processing unit 112 waits for a heartbeat (NO in step S116), and when a heartbeat has been received from the central device 12 via the communication unit 111 (YES in step S116), the processing unit 112 performs a process of decoding the heartbeat.

[0068] Next, if the processing unit 112 cannot decrypt the heartbeat (NO in step S117), it terminates the communication connection with the central device 12 (step S118). On the other hand, if the processing unit 112 can decrypt the heartbeat (YES in step S117), it encrypts a response message using the created common key (step S119) and transmits radio waves including the response message, which is encrypted information, to the central device 12 via the communication unit 111 (step S120).

[0069] Next, in the central device 12, the communication unit 121 checks whether or not a response message has been received from the peripheral device 11. More specifically, if the communication unit 121 has not received a response message (NO in step S121), it waits for a response message from the peripheral device 11. On the other hand, if the communication unit 121 has received a response message from the peripheral device 11 (YES in step S121), the RSSI measurement unit 1232 in the communication unit 121 measures RSSI indicating the reception strength of the radio wave including the response message, and outputs it to the judgment unit 124. In addition, the communication unit 121 outputs a reception notification indicating that the response message has been received to the RTT measurement unit 1231.

[0070] Next, upon receiving the reception notification from the communication unit 121, the RTT measurement unit 1231 calculates the RTT from the difference between the transmission time of the heartbeat and the reception time of the response message, and outputs the RTT to the determination unit 124 (step S122).

[0071] Furthermore, when the processing unit 122 receives a response message from the peripheral device 11 via the communication unit 121, the processing unit 122 performs a process of decrypting the response message using the created common key. If the processing unit 122 cannot decrypt the response message (NO in step S123), it rejects the entry of the peripheral device 11 (step S124). On the other hand, if the processing unit 122 can decrypt the response message (YES in step S123), it outputs a decryption completion notification indicating that to the judgment unit 124. Note that the processes of steps S122 and S123 may be performed in reverse order or in parallel.

[0072] Next, the determination unit 124 determines whether the central unit 12 is in the calibration mode or the evaluation mode based on the RTT and RSSI from the RTT measurement unit 1231 and the RSSI measurement unit 1232, and the decoding completion notification from the processing unit 122. If the central unit 12 is in the calibration mode (YES in step S124), the determination unit 124 performs a calibration process of various parameters used when evaluating the validity of the radio waves from the peripheral device 11.

[0073] More specifically, the determination unit 124 repeats sending a heartbeat to the peripheral device 11 and receiving a response message from the peripheral device 11 for a predetermined period of time, and acquires a plurality of RTTs and a plurality of RSSIs. The determination unit 124 calculates the standard deviation of the acquired plurality of RTTs, the standard deviation of the acquired plurality of RSSIs, and the covariance of each set of RTT and RSSI.

[0074] Specifically, the standard deviation of RTT, SD-RTT, is expressed by the following formula (1).

number

[0075] The standard deviation of RSSI, SD-RSSI, is expressed by the following equation (2).

number

[0076] The covariance COV of the pair of RTT and RSSI is expressed by the following equation (3).

number

[0077] The determination unit 124 calculates three parameters expressed by the following formulas (4) to (6) based on the calculated standard deviation of the RTT, and the standard deviation and covariance of the RSSI.

number

number

number

[0078] The determination unit 124 sets the calculated three parameters as reference values, stores them in the storage unit 125 as a parameter group matrix expressed by the following equation (7) (step S125), and determines whether the calibration mode is to be continued. If, for example, the peripheral device 11 is moved to a new location and the calibration mode is to be continued (YES in step S126), the determination unit 124 repeats the processes of steps S114 to S125. If the calibration mode is not to be continued (NO in step S126), the determination unit 124 ends the calibration process (step S127).

number

[0079] FIG. 6 is a diagram illustrating an example of a parameter group stored in a storage unit in the smart entry system according to the embodiment of the present disclosure.

[0080] 6, when the smart entry system 1 includes a plurality of peripheral devices 11, the determination unit 124 calculates the above-mentioned parameter group matrix for each peripheral device 11, and stores the calculated parameter group matrix in the storage unit 125 in association with the ID of each peripheral device 11.

[0081] Referring again to FIG. 5, when the evaluation mode is selected in step S101 (NO in step S124), the judgment unit 124 evaluates the legitimacy of the radio waves based on multiple types of measurement results by the measurement unit and a judgment criterion based on the distribution of each measurement result acquired in advance, and judges whether to allow entry based on the evaluation result.

[0082] More specifically, the determination unit 124 evaluates the validity of the radio wave based on the Mahalanobis distance calculated from the distribution of RTT and RSSI, which are the results of multiple types of measurements by the measurement unit, and the determination criterion. Specifically, the determination unit 124 receives the RTT and RSSI from the RTT measurement unit 1231 and the RSSI measurement unit 1232, respectively, acquires each parameter of the formula (7) representing the above-mentioned reference value from the storage unit 125, and calculates the Mahalanobis distance from the RTT and RSSI, which are the results of measurements, by the formula expressed on the left side of the following formula (8) (step S128).

number

[0083] Next, the determination unit 124 obtains a threshold value thr, which is a determination criterion determined based on the parameters expressed by the formula (7) calculated in the previous calibration mode, from the storage unit 125. When the smart entry system 1 includes a plurality of peripheral devices 11, the determination unit 124 obtains the threshold value thr for each peripheral device 11 from the storage unit 125. The threshold value thr is stored in the storage unit 125 in advance.

[0084] Next, the judgment unit 124 judges whether the calculated Mahalanobis distance is less than the threshold thr. If the Mahalanobis distance is greater than the threshold thr (NO in step S129), the judgment unit 124 judges that the radio waves from the peripheral device 11 are not valid, and rejects the entry of the peripheral device 11 (step S124). On the other hand, if the Mahalanobis distance is less than the threshold thr (YES in step S129), the judgment unit 124 judges that the radio waves from the peripheral device 11 are valid, and permits the entry of the peripheral device 11 (step S130). The processes of steps S114 to S130 are repeated, for example, periodically, while the communication connection between the peripheral device 11 and the central device 12 is established.

[0085] When the user 80 carrying the peripheral device 11 moves away from the central device 12 by a predetermined distance or more, the peripheral device 11 becomes unable to decode the heartbeat from the central device 12 (NO in step S117) and terminates the communication connection with the central device 12 (step S118). At this time, if the door 90 is unlocked, the door 90 is locked. Also, the central device 12 becomes unable to decode the response message from the peripheral device 11 (NO in step S123) and rejects the entry of the peripheral device 11 (step S124). At this time, if the door 90 is unlocked, the door 90 is locked.

[0086] Meanwhile, there is a demand for a technology that can more accurately detect unauthorized entries, such as relay attacks, against a smart entry system.

[0087] For example, possible methods include a method of determining fraudulent entry using one of the physical quantities, RTT and RSSI, of the radio waves transmitted from the peripheral device to the central device, or a method of determining fraudulent entry using a motion sensor that identifies the coordinates of at least one of the peripheral device and the central device.

[0088] However, in the method using one of the physical quantities of the RTT and RSSI of radio waves, the RTT or RSSI may be spoofed, and unauthorized entries such as relay attacks may not be detected correctly. In addition, in the method using a motion sensor, the manufacturing cost and power consumption of the peripheral device or central device increases.

[0089] In contrast, in the smart entry system 1 according to the embodiment of the present disclosure, the validity of radio waves transmitted from the peripheral device 11 to the central device 12 is evaluated based on the Mahalanobis distance calculated from the measurement results of both RTT and RSSI and the Mahalanobis distance criterion acquired in advance, and the permission of entry is determined based on the evaluation result. With this configuration, the relationship between the distance between the central device 12 and the peripheral device 11 and the radio wave strength at that distance can be appropriately derived. This makes it possible to improve the accuracy of the evaluation compared to when the validity of radio waves is evaluated based on the measurement results of either RTT or RSSI, and to reduce false positive or false negative judgments in relay attack detection, for example. In addition, by using the Mahalanobis distance, it is possible to suppress a decrease in the evaluation accuracy even when there is a change in signal strength due to, for example, the peripheral device 11 being housed in a case, and furthermore, it is possible to more accurately detect fraudulent entries using software processing without adding a special device with high processing power. Therefore, it is possible to more accurately detect fraudulent entries in the smart entry system.

[0090] Furthermore, in the smart entry system 1 according to the embodiment of the present disclosure, in addition to evaluating the validity of radio waves using the Mahalanobis distance, the validity of radio waves is also evaluated based on whether or not the encrypted heartbeat and response message can be decrypted. With this configuration, even if the RTT and RSSI of radio waves are spoofed and the fraudulent radio waves are determined to be valid in the evaluation using the Mahalanobis distance, entry is not permitted unless the encrypted heartbeat and response message are decrypted. Therefore, the security of the smart entry system 1 can be further improved.

[0091] [Variation 1] In the above embodiment, the smart entry system 1 is described as having one peripheral device 11. However, the smart entry system 1 may be configured to have a plurality of peripheral devices 11. In this case, the determination unit 124 in the central device 12 acquires a determination criterion for each of the plurality of peripheral devices 11 in advance, and evaluates the validity of the radio waves using the corresponding determination criterion for each peripheral device 11.

[0092] [Variation 2] In the above embodiment, the configuration has been described in which the RTT and RSSI are measured as multiple types of measurement results regarding radio waves. However, the central unit 12 may be configured to measure physical quantities other than the RTT and RSSI.

[0093] [Variation 3] In the above embodiment, the configuration has been described in which the Mahalanobis distance is calculated from the measured RTT and RSSI. However, the central unit 12 may be configured to calculate a confidence interval of a standard deviation from a plurality of types of measurement results and evaluate the validity of the radio waves. Alternatively, the central unit 12 may be configured to input a plurality of types of measurement results into a learning model based on machine learning and evaluate the validity of the radio waves.

[0094] [Variation 4] In the above embodiment, a configuration has been described in which the smart entry system 1 includes the lock mechanism 13. However, the smart entry system 1 may be configured not to include the lock mechanism 13. For example, the central device 12 may be configured to determine whether or not to permit entry to a predetermined area in a certain space.

[0095] [Variation 5] In the above embodiment, the smart entry system 1 is described as being applied to an entrance / exit of a facility such as a house. However, the smart entry system 1 may also be applied to, for example, a smart key system of a vehicle. That is, the central device 12 may be an in-vehicle device mounted on a vehicle, and the peripheral device 11 may be a smart key that unlocks or locks the door of the vehicle. The smart entry system 1 may also be applied to an entry system where a worker is expected to enter or exit with both hands full, such as an entry / exit system for a treatment room in a hospital and an entry / exit system for each work room in a factory.

[0096] The above-described embodiments should be considered as illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0097] The above description includes the following additional features. [Appendix 1] A central device; a peripheral device that transmits radio waves to the central device; The central device a communication unit that receives the radio waves transmitted from the peripheral device; A measurement unit for measuring a value related to the radio wave; a determination unit that evaluates the validity of the radio waves based on a plurality of types of measurement results by the measurement unit and a determination criterion based on a distribution of the measurement results previously acquired, and determines whether or not to permit entry based on the evaluation result; The central device is an in-vehicle device mounted in a vehicle, A smart entry system, wherein the peripheral device is a smart key that unlocks or locks the doors of the vehicle. [Appendix 2] A communication unit for receiving radio waves; A measurement unit for measuring a value related to the radio wave; a determination unit that evaluates the validity of the radio waves based on a plurality of types of measurement results by the measurement unit and a determination criterion based on a distribution of the measurement results previously acquired, and determines whether or not to permit entry based on the evaluation result; The central unit is an on-board device installed in a vehicle. [Explanation of symbols]

[0098] 1. Smart Entry System 11 Peripheral Devices 111 Communications Department 112 Processing section 113 Storage section 12 Central unit 121 Communications Department 122 Processing section 1231 RTT Measurement Unit 1232 RSSI measurement section 124 Judgment Department 125 Storage section 13 Locking mechanism 80 users 90 Doors

Claims

1. A central device; a peripheral device that transmits radio waves to the central device; The central device a communication unit that receives the radio waves transmitted from the peripheral device; A measurement unit for measuring a value related to the radio wave; A smart entry system including a judgment unit that evaluates the legitimacy of the radio waves based on multiple types of measurement results by the measurement unit and judgment criteria based on the distribution of each of the measurement results obtained in advance, and decides to allow entry based on the evaluation results.

2. the radio waves include encrypted information; The smart entry system according to claim 1 , wherein the determination unit evaluates the validity of the radio wave further based on whether or not the encrypted information can be decrypted.

3. The smart entry system includes a plurality of the peripheral devices, 3. The smart entry system according to claim 1, wherein the determination unit evaluates the validity of the radio waves transmitted from the corresponding peripheral device based on the determination criterion for each of the peripheral devices.

4. The smart entry system according to claim 1 , wherein the plurality of types of measurement results include a round trip time (RTT) of the radio wave and a received signal strength indication (RSSI) of the radio wave.

5. The smart entry system according to any one of claims 1 to 4, wherein the determination unit evaluates the validity of the radio waves based on a Mahalanobis distance calculated from a distribution of the multiple types of measurement results by the measurement unit and the judgment criterion.

6. The smart entry system further includes a locking mechanism controlled by the central device. The smart entry system according to claim 1 , wherein the determination unit determines whether the lock mechanism is open or closed based on the evaluation result.

7. The lock mechanism is an electronic lock provided on the door, The smart entry system according to claim 6 , wherein the determination unit switches between unlocking and locking the door by the lock mechanism based on the evaluation result.

8. A communication unit for receiving radio waves; A measurement unit for measuring a value related to the radio wave; A central device comprising: a judgment unit that evaluates the legitimacy of the radio waves based on multiple types of measurement results by the measurement unit and a judgment criterion based on the distribution of each of the measurement results acquired in advance, and judges whether to allow entry based on the evaluation result.

9. A smart entry program used in a central device that receives radio waves from peripheral devices, Computer, A measurement unit for measuring a value related to the radio wave; a determination unit that evaluates the validity of the radio waves based on a plurality of types of measurement results by the measurement unit and a determination criterion based on a distribution of the measurement results previously acquired, and determines whether entry is permitted based on the evaluation result; Smart entry program to function as.

10. A smart entry method in a central device, comprising: receiving radio waves from a peripheral device; measuring a value related to the radio wave; A smart entry method comprising a step of evaluating the legitimacy of the radio waves based on multiple types of measurement results of the radio waves and a judgment criterion based on the distribution of each of the measurement results obtained in advance, and determining whether to allow entry based on the evaluation results.

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