JP2020033707A - Electronic key system, authentication device and portable device - Google Patents

Abstract

To provide an electronic key system and the like which are capable of avoiding establishment of illegal authentication while securing convenience of a user.SOLUTION: An electronic key system 100 is configured to include an authentication ECU 10 and a portable device 50. The authentication ECU 10 includes an authentication-side receiving unit 20 which can receive an RF wave Crf, an authentication-side transmitting unit 30 which transmits an LF wave Clf, and an intensity setting unit 45 which generates intensity information used for setting the transmission intensity of the RF wave Crf by the portable device 50 on the basis of the reception intensity of the RF wave Crf and transmits the intensity information from the authentication-side transmitting unit 30 by carrying the intensity information on the LF wave Clf. The portable device 50 includes a portable-side receiving unit 60 capable of receiving the LF wave Clf, a portable-side transmitting unit 70 for transmitting the RF wave Crf to the authentication ECU 10, and an intensity adjusting unit 82 for performing adjustment to suppress the transmission intensity of the RF wave Crf transmitted from the portable-side transmitting unit 70 on the basis of the received intensity information.SELECTED DRAWING: Figure 3

Description

  The disclosure according to this specification relates to an electronic key system for performing authentication of a portable device carried by a user, and a vehicle-mounted device and a portable device used in the electronic key system.

  2. Description of the Related Art Conventionally, for example, Patent Literature 1 discloses a vehicular electronic key system that includes a portable device and a vehicle-mounted device, and releases a door lock of a vehicle or the like when the portable device is authenticated by the vehicle-mounted device. The portable device disclosed in Patent Literature 1 includes a portable device-side receiving unit that receives a verification signal transmitted from an on-vehicle device, a portable device-side transmitting unit that transmits an instruction signal and a response signal, and a signal transmitted from the portable device. And an output adjustment unit for adjusting the output level of the power supply. In the vehicular electronic key system of Patent Document 1, the output level of the response signal is made smaller than the output level of the instruction signal in order to prevent unauthorized unlocking or the like due to a relay attack using a repeater.

JP 2017-101496 A

  Generally, a radio wave transmitted from a portable device of a vehicular electronic key system tends to be easily affected by a shield or the like existing between a user and a vehicle. Therefore, if the output level of the response signal is simply reduced as in Patent Document 1, the response signal becomes difficult to be received by the vehicle-mounted device even when the user uses the portable device properly. As a result, even if it can be effective in preventing unauthorized unlocking and the like, there is a possibility that the convenience of a legitimate user may be impaired.

  An object of the present disclosure is to provide an electronic key system or the like that can avoid establishment of unauthorized authentication while ensuring user convenience.

  In order to achieve the above object, one embodiment disclosed includes a portable device (50) carried by a user (OW) and an authentication device (10) for authenticating the portable device by wireless communication with the portable device. An authentication key receiving unit (20) capable of receiving a first radio wave (Crf) transmitted by the portable device, and transmitting a second radio wave (Clf) to the portable device. The authentication-side transmitting unit (30) and intensity information used for setting the transmission intensity of the first radio wave by the portable device are generated based on the reception intensity of the first radio wave received by the authentication-side reception unit. A strength setting unit (45) for transmitting information from the authentication-side transmitting unit by carrying information on the second radio wave, wherein the portable unit is capable of receiving the second radio wave transmitted by the authentication machine (60). And a portable transmission unit (70) for transmitting the first radio wave to the authentication device , Based on the received intensity information by the mobile-side receiving unit, the intensity adjustment unit for adjusting to suppress the transmission strength of the first radio wave transmitted from the portable side transmitter section (82), it is an electronic key system comprising a.

  In this aspect, intensity information used for setting the transmission intensity in the portable device is generated based on the reception intensity of the first radio wave actually received by the authentication-side receiving unit. Therefore, in the portable device, it is possible to adjust the transmission intensity in consideration of the influence of the shield and the noise. Therefore, even if the adjustment for suppressing the transmission intensity of the first radio wave is performed, according to the regular use of the portable device by the user, the authentication-side receiving unit of the authentication device can stably receive the first radio wave. Therefore, authentication of the portable device by the authentication device can be smoothly performed.

  On the other hand, when the user is away from the vehicle and receives a relay attack using a repeater, the adjustment of suppressing the transmission intensity of the first radio wave reduces the reach of the first radio wave. This makes it difficult for the relay attack repeater or the authentication-side receiving unit to receive the first radio wave. Therefore, establishment of authentication in a situation where the user is away from the vehicle may be difficult. Therefore, it is possible to avoid establishment of unauthorized authentication while ensuring user convenience.

  It should be noted that the reference numbers in the parentheses merely show an example of a correspondence relationship with a specific configuration in the embodiment described later, and do not limit the technical scope at all.

1 is a diagram schematically illustrating an overall image of an electronic key system according to an embodiment of the present disclosure. FIG. 3 is a diagram illustrating an example of an arrangement of a plurality of LF transmission antennas provided on a vehicle. FIG. 2 is a block diagram illustrating an electrical configuration of the electronic key system. It is a figure for explaining the details of a relay attack. It is a figure which shows the detail about adjustment of RF wave transmission intensity by cooperation of an authentication ECU and a portable device. FIG. 4 is a sequence diagram illustrating details of an authentication process performed by the electronic key system.

  The electronic key system 100 according to an embodiment of the present disclosure illustrated in FIGS. 1 to 3 is used in a vehicle V, and includes a portable device 50, an authentication ECU (Electronic Control Unit) 10, and the like. The electronic key system 100 performs authentication of the portable device 50 previously associated with the authentication ECU 10 by wireless communication between the portable device 50 and the authentication ECU 10 using radio waves of a predetermined frequency band. The electronic key system 100 realizes a function of a smart entry in the vehicle V. The user OW, who is the owner of the vehicle V, wears the portable device 50 to lock and unlock the door lock of the vehicle V, start the drive unit for traveling, and the like without using a mechanical key. it can.

  In the electronic key system 100, the authentication ECU 10 and the portable device 50 use radio waves of different frequency bands for transmitting information. Transmission of information from the authentication ECU 10 to the portable device 50 uses an LF (Low Frequency) band radio wave (hereinafter, “LF wave Clf”). The LF band is, specifically, a frequency band of 30 kHz to 300 kHz. The authentication ECU 10 uses, for example, a 125 kHz or 134 kHz radio wave as the LF wave Clf.

  On the other hand, transmission of information from the portable device 50 to the authentication ECU 10 uses radio waves in the UHF (Ultra High Frequency) band of the RF (Radio Frequency) band (hereinafter, “RF wave Crf”). The UHF band is, specifically, a frequency band of 300 MHz to 3 GHz. The portable device 50 uses a 315 MHz or 920 MHz radio wave as the RF wave Crf. The frequency of the RF wave Crf is set higher than the frequency of the LF wave Clf. The RF wave Crf can reach farther than the LF wave Clf. On the other hand, the reach of the RF wave Crf is more apt to fluctuate than that of the LF wave Clf due to the influence of a shield and noise.

  The portable device 50 is a smart key carried by the user OW. The portable device 50 is formed in a size that can be accommodated in a pocket or the like of the user OW, for example. The portable device 50 includes an operation switch 51, a portable receiving unit 60, a portable transmitting unit 70, and a portable device control circuit 80. In addition, the portable device 50 has a built-in battery for operating the electrical components (60, 70, 80).

  The operation switch 51 is a push switch operably provided by the user OW. An unlock switch, a lock switch, and the like are provided as operation switches 51 on the housing of the portable device 50. When the unlock switch is operated, all doors or only the driver's door are unlocked. On the other hand, when the lock switch is operated, all the doors are locked. The detection result of the push operation by the operation switch 51 is sequentially acquired by the portable device control circuit 80.

  The portable receiving section 60 has an LF receiving antenna 61 that is an antenna for receiving the LF wave Clf. The portable receiving unit 60 receives the LF wave Clf transmitted by the authentication ECU 10 using the LF receiving antenna 61. As an example, the portable-side receiving unit 60 receives a wake signal, an identification number of the authentication ECU 10 (hereinafter, “vehicle ID”), intensity command information, a challenge signal, and the like from the authentication ECU 10. These signals are encrypted with an encryption key described later and received as a code (hereinafter, “LF code”).

  The LF receiving antenna 61 converts the LF wave Clf into an electric signal and outputs the electric signal to the signal processing circuit of the portable-side receiving unit 60. The portable receiving unit 60 performs signal processing such as AD conversion and demodulation on the electric signal input from the LF receiving antenna 61 by a signal processing circuit, and acquires the LF code carried by the LF wave Clf. The portable-side receiving unit 60 sequentially outputs the LF code acquired from the authentication ECU 10 by receiving the LF wave Clf to the portable device control circuit 80.

  The portable transmission unit 70 has an RF transmission antenna 71 and an output adjustment circuit 73. The RF transmission antenna 71 is an antenna for transmitting the RF wave Crf. The portable transmission unit 70 transmits the RF wave Crf received by the authentication ECU 10 using the RF transmission antenna 71. The portable transmission unit 70 transmits an Ack signal, a response signal including an identification number of the portable device 50 (hereinafter, “key ID”), a command signal, and the like to the authentication ECU 10. These signals are encrypted by an encryption key described later and transmitted as a code (hereinafter, “RF code”).

  The portable-side transmitting section 70 performs signal processing such as modulation and DA conversion on the electric signal (RF code) input from the portable device control circuit 80 by a signal processing circuit to generate a carrier signal. The portable-side transmitting section 70 outputs a carrier signal from the signal processing circuit to the RF transmitting antenna 71, and radiates the carrier signal into space as an RF wave Crf.

  The output adjustment circuit 73 is provided between the signal processing circuit and the RF transmission antenna 71. The output adjustment circuit 73 is connected to the portable device control circuit 80, and based on the adjustment signal input from the portable device control circuit 80, the radio wave intensity (transmission) of the RF wave Crf radiated into the space from the RF transmission antenna 71 based on the adjustment signal. Intensity). The output adjustment circuit 73 is, for example, a tuning circuit, and can perform adjustment to lower the transmission intensity of the RF wave Crf by performing control to slightly shift the resonance frequency of the tuning circuit from the resonance frequency of the RF transmission antenna 71. Note that an attenuator, a variable gain amplifier, and the like may be employed as the output adjustment circuit 73.

  The portable device control circuit 80 is mainly configured by a microcontroller including a CPU, a RAM, a ROM, an I / O, and a bus line for connecting these components. The CPU is hardware for arithmetic processing coupled with the RAM, and can execute a predetermined program. The ROM has a configuration including a nonvolatile storage medium, and stores a key ID, an encryption key, and the like in addition to a plurality of programs executed by the CPU. The program stored in the ROM includes at least a communication control program for controlling wireless communication with the authentication ECU 10. The portable device control circuit 80 has functional units such as a response control unit 81 and an intensity adjustment unit 82 by executing a communication control program by the CPU.

  The response control unit 81 decrypts the LF code received by the portable receiving unit 60 using the encryption key, and acquires a wake signal, a vehicle ID, strength command information, a challenge signal, and the like. The response control unit 81 executes control according to the signal and information acquired from the authentication ECU 10. Specifically, the response control unit 81 switches the operation mode, responds to the authentication ECU 10, and requests the authentication ECU 10 to open and lock the lock.

  The response control unit 81 has a startup mode and a standby mode as operation modes. The start mode is an operation mode for performing mutual communication with the authentication ECU 10. The standby mode is an operation mode in which only a configuration necessary for detecting a wake signal is set in an operation state and battery consumption is suppressed. The response control unit 81 switches the operation mode from the standby mode to the activation mode based on the reception of the wake signal. The response control unit 81 switches the operation mode from the startup mode to the standby mode based on elapse of a predetermined time after switching to the startup mode, for example.

  When receiving the wake signal and the vehicle ID, the response control unit 81 transmits an Ack signal as a response to the authentication ECU 10. After transmitting the Ack signal, the response control unit 81 transmits a response signal as a response to the authentication ECU 10 when receiving the challenge signal. The response signal is, for example, a content obtained by combining a key ID with a challenge signal. Therefore, the signal length of the response signal is longer than the Ack signal. Further, when the input of the push operation is detected by the operation switch 51, the response control unit 81 transmits a command signal requesting unlocking or locking. The response control unit 81 encrypts each signal using the encryption key, and causes the portable transmission unit 70 to transmit the RF code as an RF code.

  The intensity adjusting unit 82 acquires the intensity command information received by the portable receiving unit 60 as the intensity information from the response control unit 81. The intensity adjustment unit 82 controls the transmission intensity of the RF wave Crf transmitted from the portable transmission unit 70 based on the intensity command information. As an example, the intensity adjustment unit 82 sets the output level of the RF wave Crf using an intensity adjustment table stored in the ROM. In the strength adjustment table, the strength command information and the adjustment signal to be output to the output adjustment circuit 73 are associated in advance. The strength adjusting unit 82 determines an adjustment signal corresponding to the strength command information by performing a process of applying the strength command information to the strength adjustment table. The intensity adjustment unit 82 outputs the determined adjustment signal to the output adjustment circuit 73, and performs adjustment for suppressing the transmission intensity of the RF wave Crf transmitted from the RF transmission antenna 71.

  The authentication ECU 10 is an electronic control unit mounted on the vehicle V as a vehicle-mounted device. The authentication ECU 10 is connected to a communication network established in the vehicle V. The authentication ECU 10 can communicate with various sensors, actuators, ECUs, and the like mounted on the vehicle V via a communication network. For example, a touch sensor 111, a start button 112, a lock button 113, a body ECU 114, a drive ECU 115, and the like are connected to the communication network. These configurations (111 to 115) provide the authentication ECU 10 with various information related to the vehicle V.

  The touch sensor 111 is installed on each door handle 130 outside the vehicle V. Touch sensor 111 detects a contact operation of user OW touching door handle 130 to unlock each door of vehicle V. The detection result of the contact operation by the touch sensor 111 is sequentially acquired by the authentication ECU 10.

  The start button 112 is a push switch or the like installed on an instrument panel or a floor console of the vehicle V. To the start button 112, a start operation for making the vehicle V operable is input by the user OW. Based on the start operation on start button 112, a signal instructing switching of the start state of vehicle V is output to the communication network. As a result, the activation state of the vehicle V is switched among the ACC on state in which the electrical components can be used, the IG on state in which the vehicle V can travel, and the off state. The activation state of the vehicle V is sequentially grasped by the authentication ECU 10.

  The lock button 113 is provided near the door handle on the indoor side of the vehicle V. A push operation for locking each door of the vehicle V is input to the lock button 113 by the user OW. The lock button 113 detects a push operation by the user OW. The detection result of the push operation by the lock button 113 is sequentially acquired by the authentication ECU 10.

  The body ECU 114 is an electronic control unit that integrally controls various actuators and the like mounted on the vehicle V. For example, the body ECU 114 is electrically connected to a door lock motor that switches the state of each door between unlocking and locking. The body ECU 114 outputs a drive signal having a content corresponding to the unlock signal or the lock signal acquired from the authentication ECU 10 to the door lock motor, and unlocks or locks the door.

  The drive ECU 115 is an electronic control unit that controls the operation of a drive unit for traveling mounted on the vehicle V. The drive unit is configured to include at least one power source such as an engine and a motor generator. Drive ECU 115 activates the drive unit based on the start signal acquired from authentication ECU 10 to bring vehicle V into a runnable state (the above-described IG ON state). The activation of the drive unit indicates the activation of the engine, the activation of the drive circuit of the motor generator, and the like.

  The authentication ECU 10 is electrically connected to the LF transmission antenna 120 mounted on the vehicle V. The authentication ECU 10 includes an authentication-side receiving unit 20, an authentication-side transmitting unit 30, and an authentication control circuit 40.

  The LF transmission antenna 120 is a transmission antenna that converts a carrier signal input from the authentication ECU 10 into an LF wave Clf and radiates it into space. A plurality of LF transmission antennas 120 are installed inside and outside the vehicle V so as to form a predetermined communication area. In the portable device 50 located in the communication area, the LF wave Clf transmitted from the LF transmission antenna 120 is received in a decodable state.

  As an example, in the vehicle V, one vehicle interior antenna 120a and four vehicle exterior antennas 120b are installed as LF transmission antennas 120 (see FIG. 2). The vehicle interior antenna 120a is installed on, for example, an instrument panel or a center console, and forms a communication area near a driver's seat. The vehicle exterior antenna 120b is installed on each door handle 130, for example, integrally with the touch sensor 111. The vehicle exterior antenna 120b forms a communication area (for example, a radius of about 5 m) outside the vehicle interior of each door.

  The authentication-side receiving unit 20 has an RF receiving antenna 21 that is an antenna for receiving the RF wave Crf. The authentication-side receiving unit 20 receives the RF wave Crf transmitted by the portable device 50 using the RF receiving antenna 21. The authentication receiving unit 20 receives from the portable device 50 an RF code obtained by encrypting the above-described Ack signal, response signal, command signal, and the like.

  The RF receiving antenna 21 converts the RF wave Crf into an electric signal and outputs the electric signal to the signal processing circuit of the authentication-side receiving unit 20. The authentication-side receiving unit 20 performs signal processing such as AD conversion and demodulation on the electric signal input from the RF receiving antenna 21 by a signal processing circuit, and acquires the RF code carried by the RF wave Crf. The authentication-side receiving unit 20 sequentially outputs the RF code acquired from the portable device 50 by receiving the RF wave Crf to the authentication control circuit 40.

  The authentication-side transmission unit 30 is electrically connected to the LF transmission antenna 120. The authentication-side transmitting unit 30 transmits the LF wave Clf received by the portable device 50 using the LF transmitting antenna 120. The authentication-side transmitting unit 30 transmits an LF code obtained by encrypting the wake signal, the vehicle ID, the strength command information, the challenge signal, and the like, to the portable device 50. The authentication-side transmitting unit 30 performs signal processing such as modulation and DA conversion on the electric signal (LF code) input from the authentication control circuit 40 by a signal processing circuit, and generates a carrier signal. The authentication-side transmitting unit 30 outputs a carrier signal from the signal processing circuit to the LF transmitting antenna 120, and radiates the carrier signal as LF wave Clf into space.

  The authentication control circuit 40 is mainly configured by a microcontroller including a CPU, a RAM, a ROM, an I / O, and a bus line for connecting these components. As the authentication control circuit 40, a microcontroller that has higher computational power and higher power consumption than the portable device control circuit 80 is employed. The CPU is hardware for arithmetic processing coupled with the RAM, and can execute a predetermined program.

  The ROM includes a nonvolatile storage medium, and stores a vehicle ID, a key ID of the portable device 50 to be authenticated, an encryption key, and the like, in addition to a plurality of programs executed by the CPU. This encryption key is the same as the encryption key stored in the ROM of the portable device control circuit 80. The program stored in the ROM includes at least an authentication program that enables smart entry.

  The authentication control circuit 40 executes functional units such as the vehicle information acquisition unit 41, the vehicle state determination unit 42, the authentication processing unit 43, the entry execution unit 44, the strength setting unit 45, and the authentication suspension unit 46 by executing the authentication program by the CPU. Have.

  The vehicle information acquisition unit 41 acquires vehicle information from a communication network. The vehicle information includes a detection result of the touch sensor 111 indicating whether or not the user is touching the door handle 130, information indicating an activation state of the vehicle V based on the operation of the start button 112, and a detection result of a push operation by the lock button 113. Etc. are included. In addition, the vehicle information acquisition unit 41 acquires information indicating the locked state and the open / closed state of each door, information indicating the depressed state of the brake pedal, and the like as vehicle information.

  The vehicle state determination unit 42 determines the current state of the vehicle V based on the vehicle information acquired by the vehicle information acquisition unit 41. The vehicle state determination unit 42 determines whether or not the vehicle V is in a parking state as one of the vehicle states based on the vehicle information. Specifically, when the drive unit is in the stop state and all the doors are in the locked state, the vehicle state determination unit 42 determines that the vehicle is in the parking state. The authentication process described later is performed when the vehicle V is in a parking state.

  The authentication processing unit 43 performs generation and encryption of each signal to be transmitted to the portable device 50 and decryption of each signal (RF code) received from the portable device 50 as a series of authentication of the portable device 50. I do. Specifically, the authentication processing unit 43 starts transmitting a wake signal, triggered by an operation by the user OW. The authentication processing unit 43 repeatedly transmits the wake signal at a predetermined polling cycle (for example, 300 ms).

  When receiving the Ack signal responding to the wake signal, the authentication processing unit 43 codes the vehicle ID of the own vehicle and the like, and transmits the code on the LF wave Clf. Further, when receiving the Ack signal responding to the notification of the vehicle ID or the like, the authentication processing unit 43 transmits the encrypted challenge signal on the LF wave Clf. The challenge signal is a random number or the like used as a password for authentication of the portable device 50.

  When receiving the response signal in response to the challenge signal, the authentication processing unit 43 authenticates the portable device 50 as the transmission source based on the content of the response signal. Specifically, the authentication processing unit 43 checks the random number as a password included in the response signal and the key ID of the portable device 50. The authentication processing unit 43 authenticates the portable device 50 when the random number of the response signal matches the random number transmitted by the challenge signal and the key ID of the response signal matches the registered key ID. Then, predetermined operations such as unlocking, locking and starting are permitted.

  The entry execution unit 44 transmits a predetermined control signal to the body ECU 114, the drive ECU 115, and the like based on an operation input by the user OW when the portable device 50 is authenticated by the authentication processing unit 43 and the predetermined operation is permitted. Output. The entry execution unit 44 acquires the command signal transmitted by the portable device 50 and decoded by the authentication processing unit 43, and the detection result of each operation by the touch sensor 111 and the lock button 113.

  The entry execution unit 44 outputs an unlock signal to the body ECU 114 when acquiring a command signal for instructing unlocking of the door or when detecting a touch operation on the touch sensor 111. The entry execution unit 44 outputs a locking signal to the body ECU 114 when a command signal instructing locking of the door is acquired or when a push operation on the locking button 113 is detected. In addition, when a start operation is input to the start button 112, the entry execution unit 44 outputs a start signal to the drive ECU 115. The entry execution unit 44 can execute, in addition to the above-described control, turning on and off the lighting, starting the in-vehicle air conditioning system, and the like.

  The strength setting unit 45 and the authentication suspending unit 46 are functional units that contribute to reducing unauthorized unlocking and starting due to a relay attack. In the relay attack, a third party (thief Thf) different from the user OW illegally establishes authentication by using the relay RLY shown in FIG. The repeater RLY has a function of amplifying or relaying at least the LF wave Clf among the LF wave Clf and the RF wave Crf used in the electronic key system 100.

  When the user OW is away from the vehicle V, the thief Thf relays the LF wave Clf transmitted from the authentication ECU 10 by the repeater RLY to reach the portable device 50 owned by the user OW. As a result, the portable device 50 can receive the LF wave Clf, and transmits the RF wave Crf in response to the LF wave Clf. When the RF wave Crf is received by the authentication ECU 10 via the relay RLY or directly, the thief Thf can enter the vehicle V.

  In order to prevent the unauthorized authentication from being performed by such a relay attack, the strength setting unit 45 adjusts the transmission strength of the RF wave Crf in cooperation with the strength adjustment unit 82 of the portable device 50, as shown in FIGS. Is carried out. The strength setting unit 45 detects the reception strength of the RF wave Crf received by the mobile reception unit 60, and acquires the value of RSSI (Received Signal Strength Indication).

  In the intensity setting unit 45, the receivable intensity Srec of the RF wave Crf in the portable-side receiving unit 60 is set. The receivable strength Srec is the minimum radio wave strength received by the authentication ECU 10 in a state where the RF wave Crf transmitted from the RF transmission antenna 71 can be decoded. The strength setting unit 45 sets the transmission strength of the RF wave Crf in the portable device 50 when the measured strength Same of the RF wave Crf actually received by the authentication-side receiving unit 20 exceeds the receivable strength Srec. The intensity information to be used is generated based on the acquired RSSI.

  As an example, the intensity setting unit 45 generates intensity command information that specifies the transmission intensity of the RF wave Crf. The strength command information is information indicating a difference between the actually measured strength Same of the RF wave Crf actually received by the authentication-side receiving unit 20 and the receivable strength Srec. As an example, the intensity setting unit 45 generates intensity instruction information using an instruction generation table stored in the ROM. In the command generation table, the RSSI value and the strength command information are associated in advance. The strength setting unit 45 generates strength command information corresponding to the reception strength of the RF wave Crf by a process of applying the RSSI value to the command generation table.

  The intensity setting unit 45 causes the authentication-side transmission unit 30 to transmit the generated intensity command information on the LF wave Clf. The strength adjusting unit 82 of the portable device 50 that has obtained the strength command information applies the strength command information to the strength adjustment table so that the surplus SP of the measured strength Same with respect to the receivable strength Srec is reduced. 73 to adjust the transmission intensity of the RF wave Crf. The adjustment for suppressing the transmission intensity of the RF wave Crf is not performed on the RF wave Crf carrying the Ack signal, but is selectively performed only on the RF wave Crf carrying the response signal.

  The authentication suspending unit 46 suspends the authentication processing of the portable device 50 when the RF wave Crf having an output exceeding the specific strength is received by the authentication-side receiving unit 20. When the repeater RLY used for the relay attack has a function of amplifying the RF wave Crf, the RSSI measured by the intensity setting unit 45 is a value that cannot be normally observed. Therefore, the authentication suspending unit 46 transmits the LF code based on the measured radio wave intensity value (output level) so that the authentication processing unit 43 does not establish the authentication when the RSSI exceeds the specific intensity. To stop.

  Assuming that the specific strength used in the determination of stopping the transmission of the LF code in the authentication suspending unit 46 is a threshold Smax, the threshold Smax is set to the maximum strength of the RF wave Crf. More specifically, the threshold value Smax is a state in which the portable transmission unit 70 is physically closest to the authentication reception unit 20, that is, a state in which the portable device 50 is in close contact with the installation location of the RF reception antenna 21 outside the vehicle. Is the radio wave intensity of the RF wave Crf received by the authentication receiving unit 20. At this time, it is assumed that the output adjustment circuit 73 has not performed the output suppression adjustment of the RF wave Crf.

  Next, details of a series of authentication processes performed by the electronic key system 100 will be described with reference to FIGS. 1 and 5 based on a sequence diagram shown in FIG. 6 is started by the authentication ECU 10 on condition that a predetermined operation is input by the user OW when the vehicle V is parked, for example. When the transmission and reception of the LF wave Clf and the RF wave Crf are not established, the authentication ECU 10 and the portable device 50 appropriately end the authentication processing due to a timeout. Further, S11 to S21 are performed by the authentication ECU 10, and S51 to S59 are performed by the portable device 50.

  In S11, the transmission of the wake signal is repeated at a predetermined polling cycle. The wake signal transmitted in S11 is received by the portable device 50 in S51. In S52, the operation mode of the portable device 50 is switched from the standby mode to the activation mode, and the process proceeds to S53. In S53 and S12, the Ack signal serving as a response to the wake signal is transmitted on the RF wave Crf from the portable device 50 to the authentication ECU 10.

  In S13, the RSSI value is acquired by measuring the reception intensity of the RF wave Crf received in S12, and the process proceeds to S14. In S14, the value of the RSSI acquired in S13 is compared with a threshold value Smax. If it is determined in step S14 that the RSSI value is equal to or greater than the threshold value Smax, the process proceeds to step S15. In S15, in consideration of the possibility of the relay attack, the setting for stopping the transmission of the LF wave Clf is performed, and the series of authentication processing ends.

  On the other hand, when it is determined in S14 that the RSSI value is less than the threshold value Smax, the process proceeds to S16. In S16, intensity command information is generated based on the RSSI value acquired in S13, and transmitted together with the vehicle ID and the like. The signal (LF code) transmitted in S16 is received by portable device 50 in S54. In S55 and S17, the Ack signal serving as a response to the notification of the vehicle ID and the like is transmitted on the RF wave Crf from the portable device 50 to the authentication ECU 10.

  In S56 after the transmission of the second Ack signal, an adjustment for suppressing the transmission strength of the RF wave Crf is performed based on the strength indication information received in S54. On the other hand, the authentication ECU 10 generates a challenge signal based on the reception of the Ack signal in S17. In S18, the generated challenge signal is transmitted on the LF wave Clf. The challenge signal transmitted in S18 is received by the portable device 50 in S57.

  In S58, a response signal is generated by combining the challenge signal acquired in S57 with the key ID, and the process proceeds to S59. Then, in S59 and S19, the response signal is transmitted from the portable device 50 to the authentication ECU 10 with the transmission intensity adjusted in S56.

  In S20, the portable device 50 is authenticated based on the received response signal. In S20, when at least one of the challenge signal (random number) and the key ID does not match, it is determined that the authentication has not been established, and the series of authentication processing ends. On the other hand, when both the challenge signal and the key ID are collated in S20, it is determined that the authentication is established, and the process proceeds to S21. In S21, a predetermined operation is permitted, and a series of authentication processing ends. According to the permission of S21, the user OW can execute the above-described unlocking and locking of the door, starting of the drive unit, and the like.

  In the present embodiment described so far, strength information used for adjusting the RF wave Crf is generated based on the reception strength of the RF wave Crf actually received by the authentication-side receiving unit 20. Therefore, in the portable device 50, the transmission intensity can be adjusted in consideration of the influence of the shield and the noise. Therefore, even if the adjustment for suppressing the transmission intensity of the RF wave Crf is performed, when the user OW uses the portable device 50 regularly, the authentication-side receiving unit 20 can stably receive the RF wave Crf. Therefore, the authentication of the portable device 50 by the authentication ECU 10 can be performed smoothly.

  On the other hand, if the user OW receives a relay attack using the repeater RLY while being away from the vehicle, the reach of the RF wave Crf is shortened by performing adjustment to suppress the transmission intensity of the RF wave Crf. Therefore, it becomes difficult for the repeater RLY or the authentication-side receiving unit 20 to receive the RF wave Crf. Therefore, establishment of authentication in a situation where the user OW is away from the vehicle V may be difficult. Therefore, it is possible to avoid the establishment of unauthorized authentication while ensuring the convenience of the user OW.

  Here, when the RF wave Crf is amplified by the repeater RLY, the RSSI of the RF wave Crf may take a value that is not normally measured by the authentication ECU 10. Therefore, in the present embodiment, when the RF wave Crf having an output exceeding the threshold value Smax set as the specific strength is received, the authentication of the portable device 50 is interrupted. According to the execution of such an interruption, in a scene where the existence of the relay device RLY is suspected, the authentication is not substantially established. Therefore, it is possible to make unauthorized unlocking and starting by relay attack more difficult.

  In the present embodiment, the threshold value Smax for determining the interruption of the authentication process is set to the maximum strength that can be received by the authentication-side receiving unit 20. With such a setting, the interruption of the authentication process does not substantially occur in a scene where the relay device RLY is not used. As described above, according to the setting of the threshold value Smax based on the state in which the mobile-side transmission unit 70 and the authentication-side reception unit 20 are physically closest to each other, even if the interruption control of the authentication process is introduced, the user OW The convenience of is hard to be impaired.

  Further, in the present embodiment, the surplus SP of the measured strength Same with respect to the receivable strength Srec is reduced by adjustment based on the strength command information. In such adjustment, the transmission strength of the RF wave Crf is reduced to the maximum extent that the reception by the authentication-side receiving unit 20 can be managed. Therefore, when the user OW is away from the vehicle V, it becomes more difficult for the repeater RLY or the authentication-side receiving unit 20 to receive the RF wave Crf transmitted from the portable device 50. Therefore, it is possible to make it more difficult to establish unauthorized authentication by a relay attack.

  In addition, in the present embodiment, among the plurality of signals transmitted from the portable device 50 to the authentication ECU 10, such as the Ack signal and the response signal, only the response signal is adjusted to suppress the transmission intensity of the RF wave Crf to be carried. . The Ack signal has a shorter signal length than the response signal. Therefore, if the transmission strength is weakened, it becomes difficult to receive the Ack signal by the authentication-side receiving unit 20. Therefore, in consideration of the convenience of the user OW who regularly uses the portable device 50, it is desirable that the transmission strength of the Ack signal is maintained.

  On the other hand, if the response signal has a long signal length, even if the adjustment for suppressing the transmission intensity is performed, the reception by the authentication-side receiving unit 20 is possible in the use of the authorized user OW. On the other hand, at the time of the relay attack, the response signal becomes difficult to reach the authentication-side receiving unit 20. As described above, according to the intensity adjustment that weakens the transmission intensity of the response signal without suppressing the transmission intensity of the Ack signal, it is possible to ensure the convenience of the user OW and prevent unauthorized authentication from being achieved at a higher level. Can be done.

  In the present embodiment, the strength command information for designating the transmission strength of the RF wave Crf is provided from the authentication ECU 10 to the portable device 50 as strength information. By employing such a process, the process of determining the transmission intensity of the RF wave Crf in the portable device 50 can be simplified. Therefore, it is possible to reduce the power consumed by the portable device 50 in the processing related to the authentication. Alternatively, it is possible to provide the portable device 50 at a lower cost by lowering the computing capacity of the portable device control circuit 80.

  Further, in the present embodiment, the authentication ECU 10 is a vehicle-mounted device mounted on the vehicle V, and the electronic key system 100 functions as a system for authenticating the user OW of the vehicle V. Therefore, the effect of avoiding the establishment of the unauthorized authentication by adjusting the transmission intensity of the RF wave Crf can increase the security of the vehicle V and greatly contribute to the suppression of theft by the thief.

  In the first embodiment, the RF wave Crf corresponds to the “first radio wave”, the LF wave Clf corresponds to the “second radio wave”, and the threshold value Smax corresponds to the “maximum intensity”. The authentication ECU 10 corresponds to an “authentication device”, the entry execution unit 44 corresponds to a “signal output unit”, and the body ECU 114 and the drive ECU 115 each correspond to an “electric configuration”. Further, the Ack signal corresponds to a “first response signal”, and the response signal corresponds to a “second response signal”.

(Other embodiments)
As described above, one embodiment of the present disclosure has been described, but the present disclosure is not construed as being limited to the above embodiment, and is applied to various embodiments and combinations without departing from the gist of the present disclosure. be able to.

  When the RSSI exceeds the threshold value Smax (see FIG. 5), the authentication suspending unit according to the embodiment suspends the LF wave transmission, thereby suspending the authentication process. However, a specific method for forcibly interrupting the authentication process may be appropriately changed as long as transmission of the RF code including the key ID can be stopped. For example, the authentication suspending unit may cause the authentication-side transmitting unit 30 to transmit a wave-stop command signal for commanding to stop transmission of the RF wave. In the portable device that has received the wave stop command signal, the response control unit ends the authentication process and stops the transmission of the RF wave.

  In the above embodiment, the maximum strength of the receivable RF wave is used as the threshold for determining the interruption of the authentication process. However, the threshold value may be set to a value exceeding the above maximum strength in order to avoid interruption of the authentication process due to erroneous detection or the like.

  In the above embodiment, the RSSI value is obtained only for the Ack signal (S12 in FIG. 6) received for the first time. However, the intensity setting unit can also acquire the RSSI value for each of the second Ack signal (S17 in FIG. 6) and the response signal (S19 in FIG. 6). In such a mode, if the RSSI value of the response signal whose transmission strength is supposed to be adjusted indicates a value like unadjusted and exceeds a specific adjustment threshold, the authentication interrupting unit interrupts the authentication process. Can be determined. The adjustment threshold may be set based on, for example, a value of RSSI when the Ack signal is received, or may be a value set in advance. The adjustment threshold is set to a value larger than the receivable strength Srec (see FIG. 5) and smaller than the above-described threshold Smax (see FIG. 5) based on the maximum strength.

  In the first modification of the above-described embodiment, a process of adjusting the radio wave intensity of the RF wave is performed after receiving the intensity command information (S54 in FIG. 6) and before transmitting the Ack signal (S55 in FIG. 6). As a result, the Ack signal responding to the notification of the vehicle ID is transmitted by the RF wave on which the adjustment for suppressing the transmission intensity is reflected. According to such a process, it is difficult to establish communication between the authentication ECU and the portable device at an earlier stage when a relay attack is received. Therefore, in the first modification, it is possible to further enhance the security performance against the relay attack.

  The intensity adjustment unit and the output adjustment circuit of the above-described embodiment greatly reduce the transmission intensity of the RF wave so that the reception intensity of the RF wave in the authentication ECU becomes approximately the receivable intensity. However, the adjustment of the transmission intensity of the RF wave may be determined as appropriate. For example, the intensity adjustment unit may adjust the transmission intensity so that the reception intensity at the authentication ECU is approximately intermediate between the maximum intensity and the receivable intensity. Further, as in the above embodiment, the intensity adjusting unit may continuously change the radio wave intensity of the RF wave, or may change the radio wave intensity of the RF wave discretely (stepwise).

  In the second modification of the above embodiment, the RSSI value itself measured by the authentication-side receiving unit is transmitted to the portable device as strength information. The strength adjustment unit of the portable device determines an adjustment amount of the transmission strength, that is, an adjustment signal, by performing a process of applying the received RSSI value to the strength adjustment table. In the second modification as well, the output level of the RF wave can be adjusted.

  Further, if the reception strength of the RF wave in the authentication ECU can be reflected in the transmission strength of the RF wave in the portable device, the details of the processing for determining the strength command information, the adjustment signal, and the like may be changed as appropriate. For example, the intensity setting unit and the intensity adjustment unit use a learning function or the like generated by a preset function or machine learning instead of the command generation table or the intensity adjustment table to determine the intensity command information and the adjustment signal. Is also good.

  Further, the frequency of the radio wave used for communication between the authentication ECU and the portable device may be changed as appropriate. For example, if the first radio wave transmitted from the portable device is set to a frequency of 1 MHz or less, it may not belong to the LF band, for example. Similarly, the second radio wave transmitted from the authentication ECU may belong to a band different from the above-mentioned frequency band.

  In addition, details of signals transmitted and received between the authentication ECU and the portable device may be appropriately changed. As an example, the wake signal transmitted in the polling cycle may include information such as a vehicle ID and a challenge signal. With such a setting, the number of signal transmissions and receptions between the authentication ECU and the portable device can be reduced.

  In the above embodiment, the execution timing of the authentication process is not limited to the case where the vehicle V is parked, and may be changed as appropriate. For example, the authentication processing unit may be able to perform in-vehicle authentication for confirming that a portable device is present in the vehicle compartment and out-of-vehicle authentication for determining a portable device outside the vehicle compartment. The vehicle interior authentication includes, for example, authentication for starting the drive unit based on an input of a start operation on a start button. On the other hand, the vehicle exterior authentication includes boarding authentication when the user gets into a parked vehicle in a locked state, locking authentication in which a user who gets off the vehicle locks all doors, and the like.

  The configuration, installation position, transmittable / receivable area, and the like of each antenna of the above embodiment may be appropriately changed. Further, the LF transmitting antenna may be included in the authentication ECU. Conversely, the RF receiving antenna may be configured to be electrically connected to the authentication ECU. Similarly, the LF receiving antenna and the RF transmitting antenna may each be configured to be electrically connected to the portable device. Further, depending on the setting of the frequency of each radio wave, a plurality of antennas may be integrally formed.

  The authentication ECU according to the above-described embodiment has performed challenge-response authentication. However, the method of authentication may be changed as appropriate. For example, authentication based on a rolling code method may be performed. In addition, in the above embodiment, a common encryption key is used for encryption and decryption. However, signal encryption may be implemented by a public key cryptosystem that has a public key and a private key.

  Further, the portable device possessed by the user does not need to have a configuration dedicated to the electronic key system. The portable device may be a communication device such as a smartphone or a wearable terminal on which a specific application is installed. The first radio wave in such a form may be a radio wave of a frequency used in short-range wireless communication such as Bluetooth Low Energy (Bluetooth is a registered trademark) and Wi-Fi (registered trademark). Specifically, a radio wave of a frequency belonging to a band from 2400 MHz to 2480 MHz (hereinafter, a 2.4 GHz band) may be used as the first radio wave.

  The electronic key system of the above embodiment is used in a vehicle, and is configured to permit unlocking of each door, starting of a drive unit, and the like. However, the electronic key system is applicable to other uses. For example, the electronic key system may be used for a moving object different from a vehicle. Further, the electronic key system may be a system in which an authentication device is installed at a front entrance of a house or the like, and a user having the portable device can lock and unlock the front entrance.

  Various non-transitory tangible storage media such as an EEPROM (registered trademark) and a flash memory can be adopted as the ROM of the authentication ECU and the portable device. The form of such a storage medium may be appropriately changed. For example, the storage medium may be in the form of a card, inserted into a slot provided in the authentication ECU and the portable device, and electrically connected to a control circuit.

V vehicle, OW user, Crf RF wave (first radio wave), Clf LF wave (second radio wave), Same measured intensity, Srec receivable intensity, Smax threshold (maximum intensity), SP surplus, 10 authentication ECU (authentication device) ), 20 authenticating-side receiving unit, 30 authenticating-side transmitting unit, 44 entry executing unit (signal output unit), 45 strength setting unit, 46 authentication suspending unit, 50 portable device, 60 portable-side receiving unit, 70 portable-side transmitting unit, 82 Strength adjuster, 100 Electronic key system, 114 Body ECU (electrical configuration), 115 Drive ECU (electrical configuration)

Claims (9)

An electronic key system comprising: a portable device (50) carried by a user (OW); and an authentication device (10) for authenticating the portable device by wireless communication with the portable device,
The authentication machine,
An authentication-side receiving unit (20) capable of receiving a first radio wave (Crf) transmitted by the portable device;
An authentication-side transmitting unit (30) for transmitting a second radio wave (Clf) to the portable device;
The portable device generates intensity information used for setting the transmission intensity of the first radio wave based on the reception intensity of the first radio wave received by the authentication-side receiving unit, and generates the intensity information based on the second radio wave. And an intensity setting unit (45) for transmitting from the authentication-side transmitting unit on the
The portable device includes:
A portable receiving unit (60) capable of receiving the second radio wave transmitted by the authentication device;
A portable-side transmitting unit (70) for transmitting the first radio wave to the authenticator;
An electronic key system comprising: an intensity adjustment unit (82) that performs an adjustment to suppress the transmission intensity of the first radio wave transmitted from the mobile side transmission unit based on the intensity information received by the mobile side reception unit.   The authentication suspending unit (46) further comprising: an authentication suspending unit (46) for suspending a process of authenticating the portable device when the first radio wave having an output exceeding a specific strength is received by the authentication-side receiving unit. Electronic key system.   The said specific intensity is more than the maximum intensity (Smax) of the said 1st electric wave received by the said authentication side receiving part in the state which made the said mobile side transmission part the closest to the said authentication side receiving part. Electronic key system according to the item.   The intensity adjustment unit is configured to, when the measured intensity (Same) of the first radio wave actually received by the authentication-side receiving unit exceeds the receivable intensity (Srec) of the authentication-side receiving unit, The electronic key system according to any one of claims 1 to 3, wherein a transmission intensity of the first radio wave is adjusted based on the intensity information so that a surplus (SP) with respect to the receivable intensity of the first radio wave is reduced. . The mobile-side transmitting unit, after transmitting a first response signal that is a response to the authentication device, a second response signal longer than the first response signal, further transmitted on the first radio wave,
The said intensity adjustment part, among the said 1st response signal and the said 2nd response signal, performs only the said 2nd response signal, the adjustment which suppresses the transmission intensity of the said 1st radio wave to carry. The electronic key system according to claim 1.   The electronic key system according to any one of claims 1 to 5, wherein the intensity setting unit causes the authentication-side transmission unit to transmit, as the intensity information, intensity command information that specifies a transmission intensity of the first radio wave. The authentication machine,
An on-vehicle device mounted on a vehicle (V),
The signal output part (44) which outputs a predetermined | prescribed control signal toward the electric structure (114,115) of the said vehicle when the said portable device is authenticated, The signal output part (44) in any one of Claims 1-6 further provided. Electronic key system as described.   An authentication machine applied to the electronic key system according to claim 1.   A portable device applied to the electronic key system according to claim 1.

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