JP2011063938A - Electronic key system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic key system which improves security by inhibiting fraudulent communication from being established between an electronic key and a vehicle by using a relay machine. <P>SOLUTION: Counter signals Ske and Sca are transmitted in a direction opposite to the transmission direction of a request signal (challenge signal Scc1) or a response signal (response signal Sre1) in overlapping timing during the transmission of the request signal (challenge signal Scc1) or the response signal (response signal Sre1), between the vehicle 2 and the electronic key 10. Thus, the fraudulent communication is inhibited from being carried out between the vehicle 2 and the electronic key 10 in a position far away from the vehicle 2 by using the relay machine. Consequently, the security of the electronic key system 1 can be improved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic key system capable of unlocking a vehicle door and starting an engine by wireless communication.

  In the conventional electronic key system, when ID code verification is established through transmission / reception of various signals including the ID code between the electronic key and the vehicle, it is possible to lock and unlock the vehicle door lock, start the engine, and the like. For example, in the electronic key system disclosed in Patent Document 1, the vehicle includes an in-vehicle antenna that forms a communication area inside the vehicle and an outside antenna that forms a communication area around the vehicle. When ID code verification (external vehicle verification) is established through communication between the electronic key existing in the vehicle outside communication area and the vehicle, control for switching the lock state of the door lock is performed. On the other hand, when ID code verification (in-vehicle verification) is established through communication between the electronic key present in the in-vehicle communication area and the vehicle, engine start is permitted (see, for example, Patent Document 1).

  By the way, with recent developments in communication technology, there is a risk of unauthorized communication between an electronic key carried by a user located far away from the vehicle and the vehicle. That is, for example, even if a relay device that relays radio waves is provided between the electronic key and the vehicle and the electronic key exists far from the vehicle, a technique for establishing communication between the electronic key and the vehicle is conceivable.

Conventionally, various countermeasures have been taken against unauthorized communication using such a repeater (see, for example, Patent Document 2).
In addition, it is known that an illegal radio relay by a repeater can be suppressed by transmitting and receiving a signal in the same frequency band between the vehicle and the electronic key with respect to the above problems. Specifically, as shown in FIG. 4, the repeater 101 transmits a reception antenna 102 provided on the vehicle 121 side to receive a request signal from the vehicle 121 and the received request signal near the electronic key 122. For this purpose, a transmission antenna 103 provided on the electronic key 122 side is provided. The reception antenna 102 and the transmission antenna 103 are connected via a connection line 105.

  The repeater 101 also includes a reception antenna 108 provided on the electronic key 122 side to receive a response signal from the electronic key 122 and a transmission provided on the vehicle 121 side to transmit the received response signal to the vehicle 121 side. And an antenna 107. The reception antenna 108 and the transmission antenna 107 are connected via a connection line 106.

  Both connection lines 105 and 106 are provided with amplifier circuits 104 and 109, respectively. The amplifier circuits 104 and 109 amplify the signals received by the receiving antennas 102 and 108 and transmit them to the transmitting antennas 103 and 107 side.

  According to the above configuration, the repeater 101 transmits the request signal received via the reception antenna 102 from the transmission antenna 103 to the electronic key 122. Further, the repeater 101 receives a response signal from the electronic key 122 corresponding to the request signal via the reception antenna 108 and transmits the response signal from the transmission antenna 107 to the vehicle 121. Accordingly, communication between the vehicle 121 and the electronic key 122 is enabled by the relay 101 at a position where the electronic key 122 is away from the vehicle 121.

  Note that a pair of transmission / reception antennas may be provided between the connection lines 105 and 106 to transmit and receive request signals and response signals wirelessly. As a result, the receiving antenna 102 and the transmitting antenna 107 provided on the vehicle 121 side and the transmitting antenna 103 and the receiving antenna 108 provided on the electronic key 122 side are installed at remote locations, and radio wave relay can be performed wirelessly. It becomes.

  When the repeater 101 configured as described above transmits and receives a request signal and a response signal in the same frequency band (UHF band) between the vehicle 121 and the electronic key 122, the following phenomenon occurs. That is, a request signal from the vehicle 121 is transmitted from the transmission antenna 103 to the electronic key 122 via the reception antenna 102 and the amplification circuit 104. The electronic key 122 returns a response signal in response to the request signal from the transmission antenna 103. The reception antenna 108 receives this response signal. At this time, the receiving antenna 108 receives not only the response signal but also the request signal from the transmitting antenna 103. The request signal received by the reception antenna 108 is transmitted as a jamming radio wave from the transmission antenna 107 via the connection line 106. The request signal from the vehicle 121 interferes with jamming radio waves, and the interference request signal is transmitted from the transmission antenna 103 to the electronic key 122. The electronic key 122 determines that the mixed request signal is not a normal request signal and does not send back a response signal. Further, even if a response signal is returned from the electronic key 122, an interfering request signal emitted from the transmission antenna 103 for the response signal becomes a jamming radio wave. As described above, when the reception antennas 102 and 108 receive the request signal or the response signal that is not assumed, jamming radio waves are generated and unauthorized communication between the vehicle 121 and the electronic key 122 is prevented.

JP 2007-170162 A JP 2006-118886 A

  By the way, in the electronic key system using the signal of the same frequency band, when the transmission timing of the request signal and the response signal is analyzed, unauthorized communication between the vehicle 121 and the electronic key 122 by the repeater 101 is possible. Become. Specifically, as shown in FIG. 3, the connection lines 105 and 106 are provided with switching elements 111 and 112, respectively. A control circuit 115 is connected to the switching elements 111 and 112, and the switching elements 111 and 112 switch the connection lines 105 and 106 from the non-energized state to the energized state by a command signal from the control circuit 115. That is, the control circuit 115 switches the energization state of the connection lines 105 and 106 via the switching elements 111 and 112 in accordance with the analyzed request signal and the transmission timing of the request signal.

  Specifically, the control circuit 115 outputs a command signal to the switching element 111 at a timing at which a request signal from the vehicle 121 is transmitted, so that the connection line 105 is energized. As a result, the request signal is received via the reception antenna 102 and transmitted from the transmission antenna 103. At this time, since the connection line 106 is in a non-energized state, the request signal from the transmission antenna 103 is not received via the reception antenna 108, and consequently, the interference wave is prevented from being transmitted from the transmission antenna 107. The At the timing when transmission of the request signal is stopped, the control circuit 115 stops outputting the command signal to the switching element 111.

  In addition, the control circuit 115 outputs a command signal to the switching element 112 at a timing when a response signal from the electronic key 122 is transmitted, and puts the connection line 106 into an energized state. As a result, the response signal is received via the reception antenna 108 and transmitted from the transmission antenna 107 to the vehicle 121 side. At this time, since the request signal is not transmitted from the vehicle 121, the connection line 105 is in a non-energized state. Therefore, the response signal from the transmission antenna 107 is not received via the reception antenna 102, and as a result, it is possible to prevent the jamming radio wave from being transmitted from the transmission antenna 103.

  In this way, by switching the switching elements 111 and 112 between the non-energized state and the energized state according to the analyzed transmission timing, the above-described signal circulation is suppressed, and the above-described jamming waves are not generated. Therefore, even if communication using signals in the same frequency band is performed between the vehicle 121 and the electronic key 122, there is a risk of unauthorized communication.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an electronic key system that further improves security by suppressing unauthorized communication between an electronic key using a repeater and a vehicle. It is to provide.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
The invention according to claim 1 is mounted on the vehicle and an electronic key that is carried by the user and transmits a response signal including its own identification code in the same frequency band as the request signal in response to a request signal from the vehicle side. An in-vehicle device that transmits a request signal to the interior and exterior of the vehicle and enables unlocking of the vehicle door and starting of the vehicle engine through the success or failure of the identification code of the response signal returned from the electronic key side, In the same frequency band as the request signal transmitted from the electronic key to the onboard device at a timing overlapping with the transmission of the request signal from the onboard device, and the request signal The response signal transmitted from the in-vehicle device to the electronic key at a timing overlapping with the transmission of the first counter signal having a frequency value different from that of the response signal from the electronic key. A signal of the same frequency band, and has as its gist that at least one of the second opposed signals of different frequency values and the response signal is transmitted.

  According to this configuration, a repeater is used by transmitting an opposite signal in a direction opposite to the transmission direction of the signal at the timing when the request signal or the response signal overlaps between the vehicle and the electronic key. Thus, unauthorized communication between the vehicle and the electronic key at a position far away from the vehicle is suppressed. Specifically, the repeater receives a request signal receiving antenna for receiving a request signal from a vehicle, a request signal transmitting antenna for transmitting the request signal to the electronic key side, and a response signal from the electronic key. A response signal receiving antenna, and a response signal transmitting antenna for transmitting the response signal to the vehicle side. Here, since the request signal and the response signal are transmitted in the same frequency band as the opposite signal, both receiving antennas can receive the opposite signal.

  When the repeater is provided between the vehicle and the electronic key, the request signal in the same frequency band and the first counter signal or the response signal and the second counter signal in the same frequency are transmitted and received simultaneously and bidirectionally. Therefore, jamming radio waves are generated from the repeater. Specifically, the request signal receiving antenna of the repeater may inadvertently receive the opposite signal from the response signal transmitting antenna. Similarly, the response signal receiving antenna may inadvertently receive the opposite signal from the request signal transmitting antenna. In this way, the opposite signal that is inadvertently received by the receiving antenna is transmitted from the transmitting antenna and becomes a jamming radio wave for the normal request signal and response signal. As a result, communication between the vehicle and the electronic key via the relay is prevented, and the security of the electronic key system can be further improved.

  According to a second aspect of the present invention, in the electronic key system according to the first aspect, a transmission frequency signal including frequency information of the response signal and the first counter signal from the in-vehicle device to the electronic key, or the electronic When the transmission frequency signal including the frequency information of the request signal and the second opposite signal is transmitted from the key to the vehicle-mounted device, and the transmission frequency signal is received by the electronic key, the transmission frequency signal is included in the transmission frequency signal. When at least one of the response signal and the first opposing signal is transmitted at a frequency determined based on the signal frequency information to be received and the on-vehicle device receives the transmission frequency signal, a signal included in the transmission frequency signal The gist is to transmit at least one of the request signal and the second counter signal at a frequency determined based on frequency information.

  According to this configuration, the transmission frequency signal is transmitted in one direction between the in-vehicle device and the electronic key. The transmission frequency signal includes frequency information at the time of transmission of the request signal and the second counter signal or response signal and the first counter signal. Therefore, the transmission frequencies of the request signal, the response signal, and the counter signal can be commonly recognized by the in-vehicle device and the electronic key by exchanging the transmission frequency signal between the in-vehicle device and the electronic key. By the way, the opposite signal is in the same frequency band as the request signal or response signal transmitted simultaneously with the signal. Further, in order to prevent interference between the request signal, the response signal, and the opposite signal between the vehicle and the electronic key, it is necessary to set the frequency values so as not to be the same. In the above configuration, the request signal, the response signal, and the counter signal are transmitted with different frequency values through the transmission frequency signal exchange between the in-vehicle device and the electronic key, so that the above-described signal interference can be prevented. .

  In addition, by transmitting the transmission frequency signal, there is no need to decide in advance the transmission frequency of the request signal, response signal and counter signal for each communication between the in-vehicle device and the electronic key. For example, the signal frequency is determined at random. Can do. Therefore, it becomes more difficult to predict the frequency of various signals for each communication, and the security of the electronic key system is improved.

  According to a third aspect of the present invention, in the electronic key system according to the second aspect, the request signal includes a wake signal to activate the electronic key, and the response signal is returned in response to the wake signal. The on-vehicle device includes an ACK signal, and after confirming receipt of the ACK signal according to the wake signal, the on-board device performs authentication communication with the electronic key as to whether the electronic key is valid or not. The gist is that the transmission frequency signal is transmitted after the transmission of the ACK signal corresponding to the wake signal.

  According to this configuration, the transmission frequency signal is transmitted before authentication communication as to whether or not the electronic key is valid. Therefore, for request signals and response signals transmitted and received in highly confidential authentication communication, the frequency of those signals can be changed for each communication. Therefore, while ensuring the security of the electronic key system, it is not necessary to change the frequency of the wake signal with low confidentiality and the ACK signal corresponding to the wake signal.

  According to a fourth aspect of the present invention, in the electronic key system according to the third aspect, the in-vehicle device transmits a first challenge signal included in a request signal for requesting the response signal related to authentication communication to the electronic key. When the electronic key receives the first challenge signal, the electronic key returns a first response signal included in the response signal including the identification code of the electronic key as the response signal to the in-vehicle device, The in-vehicle device authenticates whether the electronic key is a legitimate electronic key through the success or failure of the verification of the identification code of the electronic key included in the first response signal, and the electronic key is A second challenge for requesting the in-vehicle device to transmit a second response signal including an identification code of the vehicle at a timing overlapping with the transmission of the first challenge signal Is transmitted to the in-vehicle device as the first counter signal, and when the in-vehicle device receives the second challenge signal, the first on-demand key overlaps with the transmission of the first response signal on the electronic key side. 2 is transmitted to the electronic key as the second counter signal, and the electronic key is the legitimate vehicle through the success or failure of the verification of the vehicle identification code included in the second response signal. The gist of the invention is that the vehicle door can be unlocked and the vehicle engine can be started when the electronic key and the vehicle verify the two identification codes.

  According to this configuration, a challenge signal and a response signal are transmitted as opposing signals between the vehicle and the electronic key. That is, a challenge signal and a response signal are bidirectionally transmitted and received between the vehicle and the electronic key, and the identification code is verified in the vehicle and the electronic key. Therefore, it is possible to perform a more accurate collation between the vehicle and the electronic key while suppressing unauthorized communication using the repeater.

  According to the present invention, in the electronic key system, it is possible to further improve security by suppressing unauthorized communication between the electronic key using the relay device and the vehicle.

The block diagram of an electronic key system. Timing chart of various signals. The block diagram of the relay machine which relays an electromagnetic wave between a vehicle and an electronic key. The block diagram of the relay machine which relays an electromagnetic wave between a vehicle and an electronic key.

(First embodiment)
Hereinafter, a first embodiment in which an electronic key system according to the present invention is embodied will be described with reference to FIGS.

  As shown in FIG. 1, the electronic key system 1 includes an electronic key 10 possessed by a driver of the vehicle 2 and an in-vehicle device 20 disposed in the vehicle 2. Mutual communication is automatically performed between the electronic key 10 and the vehicle-mounted device 20, and the door lock / unlock and the engine start are controlled on the condition that the mutual communication is established outside and inside the vehicle.

<Electronic key>
The electronic key 10 has a wireless communication function, and controls various in-vehicle devices through mutual communication with the in-vehicle device 20. The electronic key 10 includes an electronic key control unit 11 configured by a computer unit including a CPU, a ROM, a RAM, and the like, and a UHF receiving unit that is electrically connected to the electronic key control unit 11 and receives a radio signal in the UHF band. 12 and a UHF transmitter 13 for transmitting a radio signal in the UHF band.

  When receiving a request signal that is a UHF band radio signal transmitted from the in-vehicle device 20, the UHF receiving unit 12 demodulates the request signal into a pulse signal and outputs the demodulated demodulated signal to the electronic key control unit 11. . The electronic key control unit 11 is provided with a non-volatile memory 11a made of, for example, an EEPROM or the like, and the memory 11a decodes an ID code unique to the electronic key 10 and an encrypted transmission frequency signal Sfr described later. An encryption key used for calculation or calculation for encrypting the challenge code is stored. When the demodulated signal is input from the UHF receiver 12, the electronic key controller 11 reads the received data and outputs a response signal including the ID code registered in the memory 11a to the UHF transmitter 13. And the electronic key 10 transmits the response signal which is a radio signal of a UHF band to the vehicle 2 side via the UHF transmission part 13. In addition, the electronic key control unit 11 transmits a counter signal, which is a radio signal in the UHF band, via the UHF transmission unit 13 at a timing when a request signal is transmitted from the in-vehicle device 20. Note that information indicating that the signal is a counter signal generated from the electronic key 10 is added to the counter signal, and other ID information is not added. In the electronic key 10, the reception operation of the UHF reception unit 12 and the transmission operation of the UHF transmission unit 13 can be executed simultaneously.

  Here, the UHF receiver 12 is provided with a frequency switching circuit 12a for switching the reception frequency in the UHF band. The UHF transmitter 13 is provided with a frequency switching circuit 13a that switches the transmission frequency in the UHF band.

<In-vehicle device>
The in-vehicle device 20 includes a computer unit including a CPU, a ROM, a RAM, and the like. As shown in FIG. 1, the in-vehicle device 20 includes an in-vehicle control unit 21 that controls various in-vehicle devices, an in-vehicle transmission unit 22 that is electrically connected to the in-vehicle control unit 21, an in-vehicle transmission unit 23, and in-vehicle reception. Part 24.

  As shown in FIG. 1, the in-vehicle control unit 21 includes an engine switch 33 that is operated when the engine is started, a door lock device 34 that automatically locks and unlocks the vehicle door, and an engine that starts the engine of the vehicle 2. The control device 35 is electrically connected to a door handle sensor 32 that is provided on a door handle (not shown) and detects the presence or absence of a user's contact.

  The outside transmission unit 22 is provided, for example, inside a door handle (not shown) of a vehicle door of the vehicle 2. When the request signal is input from the in-vehicle control unit 21, the vehicle exterior transmission unit 22 modulates the request signal into a radio signal in the UHF band and transmits the request signal of the vehicle 2 via the vehicle transmission antenna 22 a at a preset intermittent period. Send to the surrounding area (external communication area).

  The in-vehicle transmission unit 23 is provided in the vehicle, and when a request signal is input from the in-vehicle control unit 21, the request signal is modulated into a radio signal in the UHF band, and the in-vehicle transmission antenna 23a is set at a preset intermittent period. To the inside of the vehicle (in-vehicle communication area). Moreover, the vehicle-mounted control part 21 transmits the opposing signal which is a radio | wireless signal of a UHF band via the in-vehicle transmission antenna 23a or the in-vehicle transmission antenna 22a at the timing at which a response signal is transmitted from the electronic key 10. Note that information indicating that the signal is a counter signal emitted from the vehicle-mounted device 20 is added to the counter signal, and other ID information or the like is not added. In the in-vehicle device 20, the transmission operation of the in-vehicle transmission antenna 23a or the out-of-vehicle transmission antenna 22a and the reception operation of the reception antenna 24a can be executed simultaneously. Further, the outside transmission unit 22 and the inside transmission unit 23 are provided with frequency switching circuits 22b and 23b for switching frequencies transmitted from the outside transmission antenna 22a and the inside transmission antenna 23a in the UHF band.

  When receiving the response signal transmitted from the electronic key 10 via the receiving antenna 24a, the in-vehicle receiving unit 24 demodulates this signal into a pulse signal and outputs the demodulated signal to the in-vehicle control unit 21. The in-vehicle control unit 21 includes a non-volatile memory 21a made of, for example, an EEPROM or the like. The memory 21a includes an ID code identical to the ID code set in the corresponding electronic key 10 and frequencies of various signals described later. A signal frequency pattern, which is the processed data, and an encryption key used for calculating a transmission frequency signal Sfr, which will be described later, or for calculating a response code are stored. The in-vehicle receiver 24 is provided with a frequency switching circuit 24b that switches the frequency received by the receiving antenna 24a in the UHF band.

  The in-vehicle control unit 21 intermittently outputs request signals to the outside transmission unit 22 and the in-vehicle transmission unit 23 at different timings. When the response signal transmitted from the electronic key 10 in response to the request signal transmitted through the in-vehicle transmission unit 22 and the in-vehicle transmission unit 23 is received by the in-vehicle reception unit 24, the in-vehicle control unit 21 receives the response signal. The ID code included is compared with the ID code recorded in the memory 21a. At this time, the in-vehicle control unit 21 determines whether the response signal transmitted from the electronic key 10 is in response to the request signal transmitted from the in-vehicle transmission unit 22 or the in-vehicle transmission unit 23. It is determined whether the vehicle exists outside the vehicle or inside the vehicle. Note that collating the ID code with the electronic key 10 via the outside transmission unit 22 is referred to as outside collation, and performing the ID code collation with the electronic key 10 via the inside transmission unit 23 is referred to as in-vehicle collation. .

  The vehicle-mounted control unit 21 sets the vehicle door in an unlockable state when the outside verification is established. In this unlockable state, the vehicle-mounted control unit 21 unlocks the vehicle door via the door lock device 34 when detecting that the user touches the outside door handle (not shown) through the door handle sensor 32.

  Further, when the in-vehicle verification is established, the engine start permission state is set. When the engine switch 33 installed in the vicinity of the driver's seat is operated in the engine start permission state, the operation signal is output to the in-vehicle control unit 21. The vehicle-mounted control unit 21 outputs a command signal to the engine control device 35 when detecting the operation signal in the engine start permission state. Based on the command signal, the engine control device 35 drives a cell motor (not shown) to start the engine.

  Next, the request signal, the response signal, the counter signal, and their frequencies will be described in detail. In brief, the frequency of the request signal, the response signal, and the opposite signal is changed for each communication based on the transmission frequency signal Sfr transmitted from the in-vehicle device 20 to the electronic key 10. Communication refers to a series of transmission / reception of a request signal and a response signal until in-vehicle verification or external verification is established.

  Here, each of the request signal and the response signal is not a single signal but a plurality of signals. That is, as shown in FIG. 2, the request signal includes a wake signal Swk, a vehicle ID signal Svi, and a challenge signal Scc1, and the response signal includes an ack signal Sac and a response signal Sre1. The request signal described above mainly corresponds to the wake signal Swk, and the response signal mainly corresponds to the response signal Sre1.

  Hereinafter, the case of outside-vehicle verification will be described. As shown in the upper part of FIG. 2, the in-vehicle control unit 21 intermittently transmits a wake signal Swk in the UHF band from the in-vehicle transmission antenna 22 a in order to confirm whether or not the electronic key 10 exists in the out-of-vehicle communication area. . The wake signal Swk is a command signal that activates the electronic key 10 in a standby state, and is repeatedly transmitted from the outside transmission antenna 22a at regular intervals.

  When the electronic key 10 enters the communication area of the wake signal Swk and receives the wake signal Swk, the electronic key 10 is switched from the standby state to the activated state by the wake signal Swk. If the electronic key 10 is normally activated at this time, the electronic key 10 returns an ACK signal Sac to the vehicle 2 to notify the fact.

  At this time, the ACK signal Sac transmitted by the electronic key 10 is set at a transmission timing to reach the in-vehicle receiving unit 24 when the in-vehicle receiving unit 24 is in a reception standby state. As shown in the lower part of FIG. 2, the in-vehicle control unit 21 performs an operation of receiving the ACK signal Sac by polling performed after transmitting the wake signal Swk. And the vehicle-mounted control part 21 will judge that the electronic key 10 exists in a communication area outside a vehicle, if the ACK signal Sac is received.

  Note that when the in-vehicle control unit 21 normally receives the ACK signal Sac in response to the wake signal Swk, the in-vehicle control unit 21 ends the polling in that cycle, and thereafter authenticates to actually confirm whether the electronic key 10 is genuine. Transition to communication operation. During this authentication communication operation, a reception standby state is entered at the timing of actually performing wireless communication with the electronic key 10.

  In performing the authentication communication operation, the vehicle-mounted control unit 21 transmits a UHF band transmission frequency signal Sfr from the vehicle-mounted transmission antenna 22a. The transmission frequency signal Sfr includes information related to the frequency of the request signal and the response signal used for the authentication communication operation, that is, the challenge signal Scc1, the response signal Sre1, and the counter signals Sca and Ske.

  As information regarding the frequency included in the transmission frequency signal Sfr, a different signal frequency pattern is selected for each transmission. Specifically, the frequency is selected as follows. That is, a plurality of signal frequency patterns are stored in the memory 21a. The signal frequency pattern is data in which countless challenge signals Scc1, response signals Sre1, and counter signals are listed. The in-vehicle control unit 21 randomly selects a predetermined signal frequency pattern from the plurality of signal frequency patterns, and includes the selected signal frequency pattern as information on the frequency in the transmission frequency signal Sfr. In order to prevent unauthorized reading of information, the in-vehicle control unit 21 performs an operation for encrypting information related to frequencies of various signals using an encryption key stored in the memory 21a, and then transmits the transmission frequency. Signal Sfr is transmitted.

  When the electronic key 10 receives the transmission frequency signal Sfr via the UHF receiving unit 12, the electronic key control unit 11 decrypts the transmission frequency signal Sfr encrypted using the encryption key stored in the memory 11a. Here, a common key method is adopted in which the encryption key used for encryption and decryption of the transmission frequency signal Sfr is a common key. The electronic key control unit 11 recognizes the signal frequency pattern selected on the vehicle 2 side by decoding the transmission frequency signal Sfr. The electronic key control unit 11 determines the frequencies of the response signal Sre1 and the counter signal Ske transmitted from the UHF transmission unit 13 based on the recognized signal frequency pattern. Thus, the transmission of the transmission frequency signal Sfr allows the electronic key 10 to recognize which signal frequency pattern is used for communication. Therefore, the in-vehicle device 20 can randomly select a signal frequency pattern without negotiating the frequency in advance between the vehicle 2 and the electronic key 10. Therefore, it becomes more difficult to predict the frequencies of various signals Scc1, Sca, Sre1, and Ske for each communication, and the security of the electronic key system 1 is improved.

  The in-vehicle control unit 21 determines the frequencies of the challenge signal Scc1 and the counter signal Ske transmitted from the outside transmission unit 22 based on a randomly selected signal frequency pattern. Here, the determined frequencies of the challenge signal Scc1 and the counter signal Ske are different values in the UHF band.

  When the electronic key 10 receives the vehicle ID signal Svi, the electronic key 10 determines whether or not the vehicle 2 is a legitimate vehicle through vehicle ID verification that checks whether or not the vehicle ID signal Svi is a normal code. Thus, by performing vehicle ID collation, even when there are a plurality of vehicles around the electronic key 10 and a request signal is received from the plurality of vehicles, only the regular vehicle and the vehicle ID signal Svi are received. Communication after transmission can be performed.

  As shown in FIG. 2, when the electronic key 10 recognizes that the vehicle ID verification has been established, the electronic key 10 returns an ACK signal Sac to the vehicle 2 to notify the fact. The in-vehicle control unit 21 enters a reception standby state after transmitting the vehicle ID signal Svi, and takes an operation state of receiving the ACK signal Sac during this operation.

  When the vehicle-mounted control unit 21 receives the ACK signal Sac normally after transmitting the vehicle ID signal Svi, the vehicle-mounted control unit 21 recognizes that the vehicle ID verification has been established with the electronic key 10, and the electronic key 10 existing in the outside communication area. Recognizes that it is paired with itself.

  When the vehicle-mounted control unit 21 recognizes that the vehicle ID verification has been established with the electronic key 10, the vehicle-mounted control unit 21 then transmits a challenge signal Scc1 from the vehicle-mounted transmitting antenna 22a. The challenge signal Scc1 includes a challenge code used as a random number and a key number of the electronic key 10 registered on the vehicle 2 side.

  At the timing when the challenge signal Scc1 is transmitted, the electronic key control unit 11 transmits the counter signal Ske from the UHF transmission unit 13, as shown in the middle part of FIG. The opposite signal Ske is transmitted for the same time as the challenge signal Scc1. Note that the transmission timings of the challenge signal Scc1 and the counter signal Ske are set in advance between the in-vehicle control unit 21 and the electronic key control unit 11 so that the transmission timings of the challenge signal Scc1 and the counter signal Ske match.

  Here, the challenge signal Scc1 and the counter signal Ske are set to different frequency values in the same frequency band in the signal frequency pattern. Therefore, the opposing signal Ske transmitted from the electronic key 10 to the in-vehicle device 20 and the challenge signal Scc1 transmitted from the in-vehicle device 20 to the electronic key 10 do not interfere with each other between the vehicle 2 and the electronic key 10. And the vehicle-mounted device 20 appropriately receive them.

  When the electronic key 10 receives the challenge signal Scc1 from the vehicle 2, the electronic key 10 compares the key number received at this time with the key number registered in the electronic key 10 to determine whether or not it is a communication target. To do. The number verification is verification for determining the master or sub key type for the electronic key 10 of the communication partner.

  The electronic key 10 for which this number verification is established returns a response signal Sre1 in which the response code is included in the ID code stored in its own memory 11a to the vehicle 2 side. The response code is a code obtained by encrypting the challenge code using the encryption key.

  Further, the in-vehicle device 20 recognizes whether or not the opposite signal Ske is received from the electronic key 10. If the in-vehicle device 20 does not receive the opposite signal Ske, it is assumed that there is a possibility of unauthorized communication by a relay device described later, and communication is performed without performing ID verification and response verification described later for the response signal Sre1. Exit.

  At the timing at which the response signal Sre1 is transmitted, the in-vehicle device 20 transmits the counter signal Sca from the outside transmission antenna 22a as shown in the upper part of FIG. The counter signal Sca is transmitted for the same time as the response signal Sre1. It is set in advance between the in-vehicle control unit 21 and the electronic key control unit 11 so that the transmission timings of the response signal Sre1 and the counter signal Sca match.

  Here, the response signal Sre1 and the counter signal Sca are set to different frequency values in the same frequency band in the signal frequency pattern. Therefore, the opposing signal Sca transmitted from the in-vehicle device 20 to the electronic key 10 and the response signal Sre1 transmitted from the electronic key 10 to the in-vehicle device 20 do not interfere with each other between the vehicle 2 and the electronic key 10. And the vehicle-mounted device 20 appropriately receive them. The electronic key 10 recognizes whether or not the opposite signal Sca is received from the in-vehicle device 20, and transmits a result signal Srs including the recognition result.

  When the response signal Sre1 is received, the in-vehicle control unit 21 compares the ID code included in the response signal Sre1 with the ID code stored in the memory 21a of the vehicle 2 and performs ID verification. Specifically, when transmitting the challenge signal Scc1, the vehicle-mounted control unit 21 also generates a response code by encrypting the challenge code with its own encryption key. Then, when the in-vehicle control unit 21 receives the response signal Sre1 from the electronic key 10 by the in-vehicle receiving unit 24, the in-vehicle receiving unit 24 compares the response code of the electronic key 10 with the response code calculated by itself, and executes response verification. When confirming that this response verification is established, the in-vehicle control unit 21 verifies whether the ID code included in the response signal Sre1 is correct.

  And the vehicle-mounted control part 21 recognizes that the electronic key 10 received the opposite signal Sca based on the received result signal Srs, and further confirms that the response verification and ID code verification are established, thereby using the vehicle verification. Processed as established. As described above, when the vehicle exterior verification is established, the vehicle door is brought into an unlockable state. In-vehicle verification is basically performed in the same manner as in-vehicle verification. When the in-vehicle verification is established, the engine start permission state is set. On the other hand, the in-vehicle control unit 21 recognizes that the electronic key 10 cannot receive the counter signal Sca based on the received result signal Srs, or if the response verification and the ID code verification are not established, the vehicle door is set as the verification failure. The process ends without entering the unlockable state or the engine start state.

Next, the mode of the radio wave relay by the relay of the request signal and response signal transmitted / received between the vehicle 2 and the electronic key 10 will be described.
Here, the case where the radio wave between the vehicle 2 and the electronic key 10 is relayed (relayed) using the relay device 101 described in the background art with reference to FIG. 3 will be described. The configuration of the repeater 101 has been described in the background art above, and thus the description thereof is omitted.

  As described in the above background art, the control circuit 115 controls the on / off operations of the switching elements 111 and 112 based on the analyzed transmission timings of the request signal and the response signal, thereby connecting the connection lines 105 and 106. Is switched between the non-energized state and the energized state.

  Specifically, as shown in FIG. 2, the time T10 from the start of transmission of the wake signal Swk to the completion of transmission of the response signal Sre1 when there is a return of the ack signal Sac is defined as one cycle. At time T10, as shown in the upper part of FIG. 2, the control circuit 115 outputs a command signal to the switching element 111 during a period in which various signals Swk, Sfr, Svi, Scc1, Sca are transmitted from the in-vehicle device 20. Thus, the connection line 105 is changed from the non-energized state to the energized state.

  That is, for example, when the transmission time of the vehicle ID signal Svi is time T01, the control circuit 115 outputs a command signal to the switching element 111 for the time T01 from the transmission start timing of the analyzed vehicle ID signal Svi. . Note that the switching element 112 is maintained in a non-energized state.

  2, the control circuit 115 outputs a command signal to the switching element 112 during a period in which various signals Sac, Sre1, Srs, and Ske are transmitted from the electronic key 10 at time T10. Thus, the connection line 106 is changed from the non-energized state to the energized state. That is, for example, when the transmission time of the ACK signal Sac is time T02, the control circuit 115 outputs a command signal to the switching element 112 for the time T02 from the analyzed transmission start timing of the ACK signal Sac. Note that the switching element 111 is maintained in a non-energized state.

  In the repeater 101 shown in FIG. 3, the wake signal Swk from the in-vehicle device 20 received by the reception antenna 102 is transmitted from the transmission antenna 103 via the connection line 105. However, at this time, no command signal is output from the control circuit 115 to the switching element 112, and the connection line 106 is in a non-energized state, so that the receiving antenna 108 does not receive the wake signal Swk. Therefore, the wake signal Swk received by the reception antenna 108 is transmitted from the transmission antenna 107, and this does not act as an interference wave of the various request signals Svi and Scc1 from the in-vehicle device 20.

  When the repeater 101 receives the ACK signal Sac from the electronic key 10 corresponding to the wake signal Swk, the control circuit 115 stops outputting the command signal to the switching element 111 and outputs the command signal to the switching element 112. . As a result, since the connection line 105 is in a non-energized state, the reception antenna 102 does not receive the ACK signal Sac transmitted from the transmission antenna 107. Similarly, even during transmission of the transmission frequency signal Sfr and the vehicle ID signal Svi, the reception antenna 108 does not receive the transmission frequency signal Sfr and the vehicle ID signal Svi by setting the connection line 106 to the non-energized state. As a result, no jamming is generated.

  As described above, when the transmission timing is analyzed, various signals Swk, Sac, Sfr, Svi until the transmission of the vehicle ID signal Svi can be relayed between the vehicle 2 and the electronic key 10 by the relay 101. It is.

  However, as described above, the opposite signal Ske is transmitted when the challenge signal Scc1 is transmitted after the vehicle ID signal Svi, and the opposite signal Sca is transmitted when the response signal Sre1 is transmitted. Therefore, the control circuit 115 outputs a command signal to both the switching elements 111 and 112 when transmitting the challenge signal Scc1 and the counter signal Ske, or the response signal Sre1 and the counter signal Sca. That is, both connection lines 105 and 106 are energized.

  At this time, the challenge signal Scc1 and the counter signal Ske, or the response signal Sre1 and the counter signal Sca are simultaneously relayed in both directions on the electronic key 10 side and the vehicle 2 side by the repeater 101. However, when both the connection lines 105 and 106 are energized, the challenge signal Scc1 and the counter signal Sca transmitted from the transmission antenna 103 can be received not only by the electronic key 10 but also by the reception antenna 108. When the challenge signal Scc1 and the counter signal Sca are received from the reception antenna 108, the challenge signal Scc1 and the counter signal Sca are transmitted as jamming radio waves from the transmission antenna 107 through the connection line 106. When the jamming radio wave interferes with the counter signal Sca and the challenge signal Scc1 transmitted from the vehicle 2 to the receiving antenna 102, communication between the vehicle 2 and the electronic key 10 using the repeater 101 becomes impossible.

  Further, when the reception antenna 102 receives the jamming radio wave transmitted from the transmission antenna 107, the jamming radio wave is also transmitted from the transmission antenna 103. This jamming radio wave interferes with the counter signal Ske and the response signal Sre1 transmitted from the electronic key 10 to the receiving antenna 108, thereby disabling communication between the vehicle 2 and the electronic key 10 using the repeater 101.

  Next, in the above background art, a case where the relay machine 101 described with reference to FIG. 4 is used will be described. In this case, since the switching elements 111 and 112 are not provided, it is the same as the state in which the command signal is always output to both the switching elements 111 and 112 of the repeater 101 shown in FIG. For this reason, when the challenge signal Scc1 and the counter signal Ske are transmitted or when the response signal Sre1 and the counter signal Sca are transmitted as described above, an interfering radio wave is generated, and the communication between the vehicle 2 and the electronic key 10 by the relay 101 becomes impossible.

  As described above, even when both types of the repeater 101 are used, unauthorized communication between the vehicle 2 and the electronic key 10 using the repeater 101 can be prevented, and the security of the electronic key system 1 can be improved. it can.

As described above, according to the embodiment described above, the following effects can be obtained.
(1) When the request signal (challenge signal Scc1) or the response signal (response signal Sre1) overlaps between the vehicle 2 and the electronic key 10, the opposite signal Ske, By transmitting Sca, unauthorized communication between the vehicle 2 and the electronic key 10 at a position far away from the vehicle 2 using the relay 101 is suppressed. More specifically, the repeater 101 receives a reception antenna 102 that receives a request signal from the vehicle 2, a transmission antenna 103 that transmits the request signal to the electronic key 10, and a response signal from the electronic key 10. Receiving antenna 108 and transmitting antenna 107 that transmits the response signal to the vehicle 2 side. Here, since the request signal and the response signal are transmitted in the same frequency band as the opposing signals Ske and Sca, both receiving antennas 102 and 108 can receive the opposing signals Ske and Sca.

  When the repeater 101 is provided between the vehicle 2 and the electronic key 10, the request signal and counter signal Sca of the same frequency band or the response signal and counter signal Ske of the same frequency are transmitted and received simultaneously and bidirectionally. Interfering radio waves are generated from the repeater 101. Specifically, the receiving antenna 102 of the repeater 101 may inadvertently receive the counter signal Ske from the transmitting antenna 107. Similarly, the reception antenna 108 may receive the counter signal Sca from the transmission antenna 103 carelessly. As described above, the opposite signals Ske and Sca that are inadvertently received by the receiving antennas 102 and 108 are transmitted from the transmitting antennas 103 and 107 and act as disturbing radio waves for the normal request signal and response signal. Thereby, communication between the vehicle 2 and the electronic key 10 via the relay device 101 is prevented, and the security of the electronic key system 1 can be further improved.

  (2) The transmission frequency signal Sfr is transmitted from the in-vehicle device 20 to the electronic key 10. The transmission frequency signal Sfr includes frequency information at the time of transmission of the response signal and the counter signal Ske. Therefore, by exchanging the transmission frequency signal Sfr between the in-vehicle device 20 and the electronic key 10, the transmission frequency of the request signal (challenge signal Scc1), the response signal (response signal Sre1), and the opposing signals Ske and Sca is changed to the in-vehicle device 20 and The electronic key 10 can be commonly recognized. By the way, the counter signals Ske and Sca are in the same frequency band as the request signal and the response signal transmitted simultaneously with the same signal. Further, in order to prevent interference between the request signal and the response signal and the opposing signals Ske and Sca between the vehicle 2 and the electronic key 10, it is necessary to set the frequency values so as not to be the same. In the above configuration, the request signal, the response signal, and the opposing signals Ske, Sca are transmitted at different frequency values through the exchange of the transmission frequency signal Sfr between the in-vehicle device 20 and the electronic key 10, and therefore the above signal Interference can be prevented.

  (3) The transmission frequency signal Sfr is transmitted before authentication communication as to whether or not the electronic key 10 is genuine. Therefore, for the challenge signal Scc1 and the response signal Sre1 transmitted and received in highly confidential authentication communication, the frequency of these signals can be changed for each communication. Therefore, while ensuring the security of the electronic key system 1, it is not necessary to change the frequency of the wake signal Swk having low secrecy and the ack signal Sac corresponding thereto.

(Second Embodiment)
Hereinafter, a second embodiment in which the electronic key system according to the present invention is embodied will be described. In the electronic key system of this embodiment, the challenge signal Scc2 and the response signal Sre2 are transmitted as the opposing signals Ske and Sca, and the vehicle 2 and the electronic key 10 are mutually verified. Is different. Hereinafter, a description will be given focusing on differences from the first embodiment. In addition, the electronic key system of this embodiment is equipped with the structure substantially the same as the electronic key system 1 of 1st Embodiment shown in FIG.

  As shown in the middle part of FIG. 2, the challenge signal Scc2 corresponding to the opposite signal Ske in the first embodiment has a challenge code and a key number, that is, the same signal as the challenge signal Scc1.

  When the in-vehicle device 20 receives the challenge signal Scc2 from the electronic key 10, it compares the key number received at this time with the key number registered in itself and compares the key type of the electronic key 10 of the communication partner ( Determine master and sub).

  As shown in the upper part of FIG. 2, the response signal Sre2 has an ID code and a response code, that is, the same signal as the response signal Sre1. When the electronic key 10 receives the response signal Sre2 from the in-vehicle device 20, the electronic key 10 executes ID verification and response verification. The electronic key 10 includes the result of both verifications in the result signal Srs and transmits it to the in-vehicle device 20.

  When the in-vehicle device 20 recognizes that both verifications on the electronic key 10 side are established based on the received result signal Srs after the ID verification and the response verification performed by itself are established, the in-vehicle or outside-vehicle verification is established. Will be treated as if As described above, when the vehicle outside verification is established, the vehicle door is set in an unlockable state, and when the vehicle interior verification is established, the engine start permission state is established.

  As described above, the challenge signals Scc1 and Scc2 and the response signals Sre1 and Sre2 are transmitted between the in-vehicle device 20 and the electronic key 10. Therefore, in the in-vehicle device 20 and the electronic key 10, collation of the key number and collation of the ID and the response code are executed mutually, and the accuracy of the collation between the vehicle 2 and the electronic key 10 can be further enhanced. Further, the point that communication using the repeater 101 can be prevented is the same as in the first embodiment.

As described above, according to the embodiment described above, the following functions and effects can be achieved in addition to the functions and effects (1) to (3) of the first embodiment.
(4) A challenge signal Scc2 and a response signal Sre2 are transmitted as opposing signals Sca and Ske between the vehicle 2 and the electronic key 10. That is, challenge signals Scc1 and Scc2 and response signals Sre1 and Sre2 are bidirectionally transmitted and received between the vehicle 2 and the electronic key 10, and ID codes are collated in the vehicle 2 and the electronic key 10, respectively. Therefore, it is possible to perform a more accurate collation between the vehicle 2 and the electronic key 10 while suppressing unauthorized communication using the repeater 101.

In addition, the said embodiment can be implemented with the following forms which changed this suitably.
In the first embodiment, the opposing signals Ske and Sca are transmitted with respect to the challenge signal Scc1 and the response signal Sre1, but in addition to this, the opposing signal may be transmitted with respect to the vehicle ID signal Svi. In this case, it is possible to prevent radio wave relay by the repeater 101 at an earlier timing.

  In the first embodiment, the opposite signal Ske is transmitted simultaneously with the challenge signal Scc1. However, if the opposite signal Ske is transmitted at an overlapping timing during transmission of the challenge signal Scc1, that is, if there is a period in which the opposite signal Ske and the challenge signal Scc1 are transmitted simultaneously, the opposite signal Ske and the challenge signal Scc1 are transmitted simultaneously. It does not have to be. The same applies to the counter signal Sca and the response signal Sre1.

  In both of the above embodiments, the common key method is adopted in which the encryption key used for encryption and decryption of the transmission frequency signal Sfr is a common key. However, as long as the transmission frequency signal Sfr can be encrypted and decrypted, not only the common key method but also a public key method may be used.

  In both the above embodiments, the request signal and response signal transmitted and received between the vehicle 2 and the electronic key 10 are in the UHF band. However, the request signal and the response signal are not limited to the UHF band as long as the request signal and the response signal are in the same frequency band that causes the repeater 101 to generate jamming radio waves.

  In the first embodiment, the opposite signal Ske is transmitted simultaneously with the transmission of the challenge signal Scc1, and the opposite signal Sca is transmitted simultaneously with the transmission of the response signal Sre1. However, transmission of the counter signal Sca or the counter signal Ske may be omitted. For example, even when the transmission of the counter signal Ske is omitted, the counter signal Sca is transmitted simultaneously with the transmission of the response signal Sre1, thereby generating an interference wave when using the repeater 101 and preventing unauthorized communication. it can.

  Further, the opposite signal may be transmitted simultaneously with the transmission of signals other than the challenge signal Scc1 and the response signal Sre1, for example, the wake signal Swk and the vehicle ID signal Svi. In this way, by increasing the number of transmissions of the counter signal, the repeater 101 is more likely to emit jamming radio waves, and it is possible to prevent unauthorized radio wave relay by the repeater 101 more reliably.

  In both the above embodiments, the transmission frequency signal Sfr is transmitted after the transmission of the wake signal Swk and before the transmission of the vehicle ID signal Svi, but the transmission timing of the transmission frequency signal Sfr is not limited to this. For example, it may be transmitted after the vehicle ID signal Svi is transmitted and before the challenge signal Scc1 is transmitted. The transmission frequency signal Sfr may be transmitted simultaneously with the wake signal Swk, in other words, the signal frequency information included in the transmission frequency signal Sfr may be added to the wake signal Swk. In this case, the signal frequency information included in the wake signal Swk becomes different information every time the wake signal Swk is transmitted.

  In both the above embodiments, the in-vehicle device 20 transmits the transmission frequency signal Sfr to the electronic key 10, but conversely, the electronic key 10 may transmit the transmission frequency signal Sfr to the in-vehicle device 20. In this case, the signal frequency pattern is stored in the memory 11 a of the electronic key control unit 11. For example, the electronic key 10 transmits the encrypted transmission frequency signal Sfr after returning the ACK signal Sac according to the wake signal Swk. By transmitting the transmission frequency signal Sfr, not only the electronic key 10 that has determined the signal frequency but also the vehicle 2 can recognize which signal frequency pattern is used for communication. Therefore, it is possible to select a signal frequency pattern at random on the electronic key 10 side without negotiating the frequency between the vehicle 2 and the electronic key 10 in advance.

  In both the above embodiments, the transmission frequency signal Sfr including the signal frequency information is transmitted from the in-vehicle device 20 to the electronic key 10, but the transmission of the transmission frequency signal Sfr may be omitted. In this case, the frequency of various signals for each communication is determined in advance between the in-vehicle device 20 and the electronic key 10. Thereby, unauthorized communication by the relay 101 can be prevented while omitting transmission of the transmission frequency signal Sfr.

Next, the technical idea that can be grasped from the embodiment will be described together with the effects.
(A) In the electronic key system according to claim 4, the electronic key includes a result signal that is a wireless signal that includes a result of verification of the identification code included in the second response signal. Send to electronic key system.

  According to this configuration, the in-vehicle device can recognize the success or failure of the verification of the identification code using the electronic key based on the received result signal.

  DESCRIPTION OF SYMBOLS 1 ... Electronic key system, 2 ... Vehicle, 10 ... Electronic key, 11 ... Electronic key control part, 11a ... Memory, 12 ... UHF reception part, 13 ... UHF transmission part, 20 ... In-vehicle apparatus, 21 ... In-vehicle control part, 21a DESCRIPTION OF SYMBOLS ... Memory, 22 ... Outside transmission part, 22a ... Outside transmission antenna, 23 ... Inside transmission part, 23a ... Inside transmission antenna, 24 ... In-vehicle receiving part, 101 ... Relay machine

Claims (4)

An electronic key that is carried by the user and transmits a response signal including its own identification code in the same frequency band as the request signal in response to a request signal from the vehicle side, and is mounted on the vehicle to send the request signal to the interior and exterior of the vehicle And an in-vehicle device that enables unlocking of the vehicle door and starting of the vehicle engine through success or failure of verification of the identification code of the response signal returned from the electronic key side,
The first frequency signal having the same frequency band as the request signal transmitted from the electronic key to the on-vehicle device at a timing overlapping with the transmission of the request signal from the on-vehicle device, and having a frequency value different from that of the request signal. Opposite signal, and
The second frequency signal having the same frequency band as the response signal transmitted from the vehicle-mounted device toward the electronic key at a timing overlapping with the transmission of the response signal from the electronic key, and having a frequency value different from the response signal. An electronic key system in which at least one of the opposite signals is transmitted. The electronic key system according to claim 1.
A transmission frequency signal including frequency information of the response signal and the first counter signal from the vehicle-mounted device to the electronic key, or a frequency signal of the request signal and the second counter signal from the electronic key to the vehicle-mounted device. Including transmit frequency signal,
When the electronic key receives the transmission frequency signal, it transmits at least one of the response signal and the first counter signal at a frequency determined based on signal frequency information included in the transmission frequency signal,
An electronic key system that transmits at least one of the request signal and the second counter signal at a frequency determined based on signal frequency information included in the transmission frequency signal when the in-vehicle device receives the transmission frequency signal . The electronic key system according to claim 2.
The request signal includes a wake signal to activate the electronic key,
The response signal includes an ACK signal returned in response to the wake signal,
After confirming receipt of the ACK signal according to the wake signal, the in-vehicle device performs authentication communication with the electronic key to determine whether the electronic key is a legitimate electronic key through transmission / reception of the request signal and the response signal. ,
The electronic key system, wherein the transmission frequency signal is transmitted after transmission of the ACK signal corresponding to the wake signal. The electronic key system according to claim 3.
The in-vehicle device transmits a first challenge signal included in a request signal for requesting the response signal for authentication communication to the electronic key,
When the electronic key receives the first challenge signal, the electronic key returns the first response signal included in the response signal including the identification code of the electronic key as the response signal to the in-vehicle device,
The in-vehicle device authenticates whether the electronic key is valid or not through successful verification of the identification code of the electronic key included in the first response signal,
In addition, the electronic key requests the vehicle-mounted device to transmit a second response signal including the vehicle identification code at a timing overlapping with the transmission of the first challenge signal on the vehicle side. The challenge signal is transmitted to the in-vehicle device as the first counter signal,
When the in-vehicle device receives the second challenge signal, the second response signal is transmitted to the electronic key as the second counter signal at a timing overlapping with the transmission of the first response signal on the electronic key side. Send
The electronic key authenticates whether the vehicle is a legitimate vehicle through success or failure of verification of the vehicle identification code included in the second response signal,
An electronic key system capable of unlocking a vehicle door and starting a vehicle engine when the verification of both identification codes is established in the electronic key and the vehicle.

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