JP5758757B2 - Electronic key system - Google Patents

Description

  The present invention relates to an electronic key system.

  Conventionally, in an electronic key system, a vehicle door can be locked and unlocked and an engine can be started through wireless communication between an in-vehicle device and an electronic key (see, for example, Patent Document 1). Specifically, the in-vehicle device transmits a wake signal for requesting a response from the electronic key inside and outside the vehicle. When receiving the wake signal, the electronic key transmits an ACK signal. When receiving the ACK signal, the in-vehicle device transmits a challenge signal including the challenge code and generates a response code by encrypting the challenge code.

  When receiving the challenge signal, the electronic key generates a response code by encrypting the challenge code included in the challenge signal. Then, the electronic key transmits a response signal including the response code and the ID code of the electronic key. The in-vehicle device collates the ID code of the received response signal with the ID code stored in advance in the device, and collates the response code of the signal with the response code generated by itself. When it is determined that the ID verification and the response verification are established, the in-vehicle device permits locking / unlocking of the vehicle door and starting of the engine. Thus, the security of communication can be improved by performing encrypted communication between the in-vehicle device and the electronic key.

  Further, in the electronic key system, so-called carry-out detection is performed in which whether or not the electronic key is taken out from the inside of the vehicle even after the engine is started is recognized through the transmission and reception of the signal (for example, see Patent Document 2). . That is, communication with high security is performed between the in-vehicle device and the electronic key every predetermined cycle even after the engine is started.

JP 2002-029385 A JP 2008-106579 A

  Here, in communication related to take-out detection, security as required in communication related to engine start is not required. However, in the electronic key system, encryption detection with high security is performed between the in-vehicle device and the electronic key in the same manner as when the engine is started, even when taking out is detected. In addition to the communication related to the take-out detection and the engine start, conventionally, the communication at the security level corresponding to the situation of the vehicle has not been performed. For this reason, communication with higher security than necessary may be performed. Therefore, it has been difficult to reduce the processing load related to communication, and thus the power consumption required for the processing. In particular, in an electronic key, a button type battery is used as a power source. For this reason, where the amount of power is limited, further reduction in power consumption is required.

  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 in which power consumption for communication is reduced while securing security.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
The invention according to claim 1 is a vehicle-mounted device that transmits a challenge code and generates a response code by encrypting the challenge code with an encryption key, an ID code unique to the in-vehicle device, and the received challenge code An electronic key that wirelessly transmits a response code generated by encrypting the response code using an encryption key, and the in-vehicle device transmits and receives the ID code, the challenge code, and the response code to and from the electronic key. When it is determined that the verification between the ID code stored in itself and the received ID code and the verification between the response code generated by itself and the received response code have been established when normal communication is performed through In an electronic key system that allows the door to be locked and unlocked or to start the engine, Vehicle apparatus, through state of the vehicle, when the security required for communication between the electronic key is determined that is not required as the normal communication, perform simplified communications with reduced encryption strength than the normal communication In this case, the in-vehicle device performs the normal communication when starting the engine, and performs the simplified communication when determining whether or not the electronic key has been taken out of the vehicle after the engine is started. As the first simplified communication and the second simplified communication, the first simplified communication is communication with reduced encryption strength by reducing the length of the challenge code and the response code or the encryption key. In the second simplified communication, encryption strength is reduced by omitting the challenge code and the response code. The vehicle-mounted device performs the normal communication when the vehicle door recognizes that the vehicle door is opened and closed in the engine stop state as the state of the vehicle, and is after the normal communication and before the engine is started. The gist is to perform the first simplified communication, and to perform the second simplified communication when determining whether or not the electronic key is taken out of the vehicle after the engine is started .

According to the configuration, when communication security is not required as much as normal communication, communication between the in-vehicle device and the electronic key is simplified. Simplification of communication means that, for example, the length of the challenge code and response code or the encryption key is reduced, or the challenge code and response code are omitted. By simplifying communication, power consumption related to communication between the in-vehicle device and the electronic key is reduced. In addition, since communication is simplified only when communication security is not required as much as normal communication, it is possible to suppress a decrease in security of the entire system.
That is, when starting an engine that requires high security, normal communication is performed without simplifying communication. Further, in so-called take-out detection for determining whether or not the electronic key has been taken out of the vehicle, simplified communication is performed because security as high as engine start is not required. Thereby, the power consumption concerning communication can be reduced, ensuring security.
Here, for example, in the first communication after the vehicle door is opened and closed with the user getting on, normal communication that is not simplified is performed. Thereafter, in the second and subsequent communications before the engine is started, the first simplified communication with the challenge code and response code or the length of the encryption key reduced is performed. In addition, in the detection of taking out the electronic key after the engine is started, second simplified communication in which the challenge code and the response code are omitted is performed. In the second simplified communication, communication is further simplified as compared with the first simplified communication. By thus simplifying communication step by step, it is possible to perform communication more suitable for the situation of the vehicle.

  According to the present invention, in the electronic key system, it is possible to reduce power consumption related to communication while ensuring security.

The block diagram which shows the structure of an electronic key system. FIG. The timing chart of the signal transmitted / received between the vehicle-mounted apparatus and electronic key which concern on the vehicle interior collation at the time of locking / unlocking of a vehicle door. The timing chart of the signal transmitted / received between the vehicle-mounted apparatus which concerns on the vehicle interior collation before the engine starting and the 2nd time and an electronic key. The timing chart of the signal transmitted / received between the vehicle equipment and electronic key in carrying out detection.

An electronic key system embodying the present invention will be described below with reference to FIGS.
As shown in FIG. 1, the electronic key system 1 includes an electronic key 10 possessed by a user and an in-vehicle device 20 provided in the vehicle 2. Hereinafter, specific configurations of the electronic key 10 and the in-vehicle device 20 will be described.

<Electronic key>
The electronic key 10 includes an electronic key control unit 11, an LF reception unit 12, and a UHF transmission unit 13.

  The electronic key control unit 11 is configured by a computer unit and includes a nonvolatile memory 11a. The memory 11a stores a key ID code unique to the electronic key 10, a vehicle ID code unique to the vehicle, and an encryption key for generating a response code.

  As shown in FIG. 3, the LF receiver 12 receives an LF (Low Frequency) band wake signal from the in-vehicle device 20 through the receiving antenna 12a. Then, the LF receiver 12 demodulates the wake signal into a pulse signal and outputs it to the electronic key controller 11.

  When the electronic key control unit 11 recognizes the wake signal, the electronic key control unit 11 generates an ACK signal and outputs it to the UHF transmission unit 13. The UHF transmitter 13 modulates the ACK signal and transmits it as a radio signal in the UHF (Ultra High Frequency) band via its own transmission antenna 13a.

  When the LF receiving unit 12 receives the vehicle ID signal via the receiving antenna 12a, the LF receiving unit 12 demodulates the vehicle ID signal into a pulse signal and outputs the pulse signal to the electronic key control unit 11. When recognizing the vehicle ID signal, the electronic key control unit 11 collates the vehicle ID code included in the signal with the vehicle ID code stored in the memory 11a (vehicle ID collation). When the electronic key control unit 11 determines that the verification of the vehicle ID code has been established, the electronic key control unit 11 generates a key ID signal including the key ID code stored in the memory 11a, and sends the generated key ID signal to the UHF transmission unit 13. Output. The UHF transmission unit 13 modulates the key ID signal and transmits it as a UHF band radio signal via its transmission antenna 13a.

  When the LF reception unit 12 receives the challenge signal via the reception antenna 12 a, the LF reception unit 12 demodulates the challenge signal into a pulse signal and outputs it to the electronic key control unit 11. When the electronic key control unit 11 recognizes the challenge signal, the electronic key control unit 11 generates a response code by encrypting the challenge code included in the challenge signal using the encryption key stored in the memory 11a. Then, the electronic key control unit 11 generates a response signal including the response code, and outputs the generated response signal to the UHF transmission unit 13. The UHF transmission unit 13 modulates the response signal and transmits it as a UHF band radio signal via its own transmission antenna 13a. The response signal and challenge signal in the above case are composed of 128-bit data.

  Further, as shown in FIG. 4, a 64-bit challenge signal may be transmitted from the in-vehicle device 20. Upon receiving the 64-bit challenge signal, the electronic key control unit 11 generates a response code from the challenge signal in the same manner as described above, and wirelessly transmits a 64-bit response signal including the generated response code.

<In-vehicle device>
As shown in FIG. 1, the in-vehicle device 20 includes an in-vehicle control unit 21, an in-vehicle transmission unit 22, an in-vehicle transmission unit 23, and an in-vehicle reception unit 24. In addition, a lock switch 36, an engine switch 33, a door lock device 34, an engine device 35, and a courtesy switch 37 are electrically connected to the in-vehicle control unit 21.

  As shown in an enlarged manner in the circle of FIG. 2, the vehicle outside transmission unit 22 is built in the outside door handle 4 of the vehicle door. The lock switch 36 is provided on the outer surface of the outside door handle 4 and outputs an operation signal to that effect to the in-vehicle control unit 21 when pressed by the user.

  The in-vehicle transmission unit 23 and the in-vehicle receiving unit 24 are provided in the approximate center of the vehicle interior. Furthermore, the engine switch 33 is provided in the vicinity of the driver's seat, and outputs an operation signal to that effect to the in-vehicle control unit 21 when pressed by the user. Further, the door lock device 34 automatically locks and unlocks the vehicle door when the vehicle door is closed. The courtesy switch 37 detects the opening / closing of the vehicle door and outputs the detection result to the in-vehicle control unit 21.

  The in-vehicle control unit 21 is configured by a computer unit and includes a nonvolatile memory 21a. The memory 21a stores a key ID code unique to the electronic key 10, a vehicle ID code unique to the vehicle, and an encryption key for generating a response code.

  When recognizing that the lock switch 36 has been operated, the in-vehicle control unit 21 generates a wake signal and outputs the generated wake signal to the outside transmission unit 22. The vehicle outside transmission unit 22 modulates the wake signal, and transmits the modulated wake signal as an LF band radio signal via its own transmission antenna 22a.

  The in-vehicle receiving unit 24 demodulates the ACK signal received via the receiving antenna 24 a into a pulse signal, and outputs the demodulated signal to the in-vehicle control unit 21. When recognizing the ACK signal, the in-vehicle control unit 21 generates a vehicle ID signal including a vehicle ID code stored in the memory 21 a and outputs the generated vehicle ID signal to the outside transmission unit 22. The vehicle exterior transmission unit 22 modulates the vehicle ID signal and transmits the modulated vehicle ID signal as an LF band radio signal via its own transmission antenna 22a.

  The in-vehicle receiving unit 24 demodulates the key ID signal received via the receiving antenna 24 a into a pulse signal, and outputs the demodulated signal to the in-vehicle control unit 21. When recognizing the key ID signal, the vehicle-mounted control unit 21 collates the key ID code included in the key ID signal with the key ID code stored in the memory 21a (key ID collation). When it is determined that the verification of the key ID code has been established, the in-vehicle control unit 21 generates a challenge signal including the challenge code and outputs it to the outside transmission unit 22. At this time, the vehicle-mounted control part 21 produces | generates a response code by encrypting a challenge code using the encryption key memorize | stored in the memory 21a. The encryption key used for this encryption is the same for the electronic key 10 and the in-vehicle device 20. That is, a common key system is adopted as an encryption system. The vehicle outside transmission unit 22 modulates the challenge signal, and transmits the modulated challenge signal as an LF band radio signal via its own transmission antenna 22a.

  The in-vehicle receiving unit 24 demodulates the response signal received via the receiving antenna 24 a into a pulse signal, and outputs the demodulated signal to the in-vehicle control unit 21. The vehicle-mounted control unit 21 collates the response code included in the response signal with the response code generated by itself (response collation). When the in-vehicle control unit 21 determines that the verification of the response code is established, the in-vehicle control unit 21 switches the locking / unlocking state of the vehicle door through the door lock device 34. Communication including transmission / reception of the 128-bit challenge signal and response signal is referred to as normal communication.

  When the vehicle-mounted control unit 21 recognizes that the vehicle door has been opened and closed through the courtesy switch 37 after unlocking the vehicle door, the vehicle-mounted control unit 21 transmits a wake signal into the vehicle through the in-vehicle transmission unit 23 and the transmission antenna 23a. Hereinafter, the vehicle-mounted control unit 21 performs normal communication with the electronic key 10 in the same manner as described above. When the in-vehicle control unit 21 determines that the response code verification is established, the vehicle interior verification state is established. When the in-vehicle control unit 21 recognizes that the engine switch 33 has been operated in the vehicle interior verification state, it starts the engine.

  There is a valid time in the vehicle interior verification state. That is, the vehicle-mounted control unit 21 determines again whether or not the vehicle interior verification is satisfied when it is determined that the effective time has elapsed since the vehicle interior verification is established. In the second and subsequent vehicle interior verifications, communication between the in-vehicle device 20 and the electronic key 10 is performed as a simplified first communication. Moreover, even if it is before progress of effective time, the vehicle-mounted control part 21 will perform 1st simple communication, when it recognizes that the other vehicle door opened and closed. Since the first vehicle interior verification is established, the security of the entire system is secured even if communication is simplified after the second time.

  As shown in FIG. 4, in the first simplified communication, the in-vehicle control unit 21 transmits a 64-bit challenge signal when it is determined that the key ID code verification has been established based on the received key ID signal. The 64-bit challenge signal has the same contents as the first half of the 128-bit challenge signal.

  In addition, when the in-vehicle control unit 21 recognizes the 64-bit response signal, the response code is collated with respect to the response signal, and when it is determined that the collation is established, the vehicle interior collation is established. This 64-bit response signal has the same contents as the first half of the 128-bit response signal.

  Further, as described in the background art, after the engine is started, the take-out detection of the electronic key 10 is detected through wireless communication between the in-vehicle device 20 and the electronic key 10. This take-out detection is executed, for example, when the vehicle door after the engine starts is opened and closed. As shown in FIG. 5, in carry-out detection, second simplified communication in which transmission / reception of a challenge signal and a response signal is omitted between the in-vehicle device 20 and the electronic key 10 is performed. In taking-out detection, high security is not required unlike when the engine is started, and thus security of the entire system is ensured even if communication is simplified.

  As shown in FIG. 5, in the second simplified communication, the in-vehicle control unit 21 receives the key ID signal and determines that the verification of the key ID code of the signal has been established, the electronic key 10 is placed in the vehicle interior. It is determined that exists. In the second simplified communication, since it is not necessary to perform encryption processing using the encryption key in the in-vehicle device 20 and the electronic key 10, the power consumption of the in-vehicle device 20 and the electronic key 10 can be reduced. In particular, in the electronic key 10, a button type battery (not shown) is used as a power source. For this reason, reduction in power consumption in the electronic key 10 is particularly beneficial where the amount of power is limited.

As described above, according to the embodiment described above, the following effects can be obtained.
(1) When communication security is not required as much as normal communication, communication between the in-vehicle device 20 and the electronic key 10 is simplified. Specifically, the number of bits of the challenge signal and the response signal is reduced in the first simplified communication, and the challenge signal and the response signal are omitted in the second simplified communication. Such simplification of communication reduces the power consumption of the in-vehicle device 20 and the electronic key 10. Further, since communication is not simplified when it is assumed that the security of the vehicle is not secured, the security of the entire system can be secured.

  (2) When starting an engine that requires high security, normal communication including transmission / reception of a 128-bit challenge signal and response signal is performed without simplifying communication. Further, in the take-out detection for determining whether or not the electronic key 10 has been taken out of the vehicle, the second simplified communication is performed because security as high as the engine start is not required. Thereby, the power consumption concerning communication can be reduced, ensuring security.

  (3) Normal communication which is not simplified is performed in the first communication when the vehicle door is opened and closed with the user getting on. Thereafter, in the second and subsequent communications before the engine is started, the first simplified communication in which the number of bits of the challenge signal and the response signal is reduced is performed. Further, in taking-out detection of the electronic key 10 after starting the engine, second simplified communication in which the challenge signal and the response signal are omitted is performed. By thus simplifying communication step by step, it is possible to perform communication more suitable for the situation of the vehicle.

(4) In the first and second simplified communications, the burden on the cryptographic process is smaller than that in the normal communications, so that communications can be performed more quickly.
In addition, the said embodiment can be implemented with the following forms which changed this suitably.

  In the above embodiment, the key ID code may be included in the response signal. In this case, when receiving the vehicle ID signal, the electronic key 10 transmits an ACK signal instead of the key ID signal.

  In the above embodiment, a 64-bit challenge signal and a response signal are transmitted and received in the second and subsequent vehicle interior verifications. However, in the second and subsequent vehicle interior verifications, an encryption key with a small number of bits may be used while maintaining the challenge signal and the response signal at 128 bits. Even in this case, it is possible to reduce processing related to encryption, and thus power consumption. Further, both the number of bits of the challenge signal and the response signal and the number of bits of the encryption key may be reduced.

Furthermore, the number of bits of the challenge signal and the response signal is not limited to 64 bits or 128 bits, and may be, for example, 32 bits or 256 bits.
-In the said embodiment, the challenge signal and the response signal were transmitted / received also in the vehicle interior collation after the 2nd time. However, in the second and subsequent vehicle interior verifications, the second simplified communication in which transmission / reception of the challenge signal and the response signal is omitted may be performed similarly to the communication at the time of taking-out detection. Conversely, the first simplified communication may be performed when taking-out is detected.

  In the above embodiment, the wake signal is transmitted outside the vehicle when the lock switch 36 is operated. However, when the engine is stopped and locked, a wake signal may be transmitted outside the vehicle at regular intervals. In this case, when the in-vehicle control unit 21 determines that the key ID verification and the response verification are established, the vehicle interior verification state is established. When the vehicle-mounted control unit 21 recognizes that the lock switch 36 has been operated in a state where the vehicle exterior verification is established, the vehicle-mounted control unit 21 switches the locking / unlocking state of the vehicle door. Also in this configuration, the first or second simplified communication may be performed in the second and subsequent vehicle exterior comparisons.

  In the above embodiment, the security level is changed by changing the communication contents between the communication related to engine start and the communication related to take-out detection. However, for example, the security level may be changed between communication related to locking the vehicle door and communication related to unlocking the vehicle door. For example, normal communication is performed in communication related to unlocking a vehicle door that requires higher security. And in the communication which concerns on locking of a vehicle door, the 1st or 2nd simplified communication is performed.

  Further, the second simplified communication may be performed in communication related to locking / unlocking of the vehicle door, and the normal communication may be performed in communication related to engine start. Further, the number of bits of the challenge signal and the response signal may be reduced for each communication, such as 128 bits → 64 bits → 32 bits.

  -In above-mentioned embodiment, when it is judged that the collation of key ID code is not materialized at the time of carrying-out detection, the vehicle-mounted control part 21 may perform normal communication again because it is doubtful that the regular electronic key 10 exists. .

  In the above embodiment, take-out detection is performed when the vehicle door is opened and closed after the engine is started. However, the carry-out detection may be executed based on the vehicle speed, the shift state, the window opening / closing state, the ignition state, the steering lock release state, the engine start state, and the immobilizer state.

Next, the technical idea that can be grasped from the embodiment will be described together with the effects.
In (b) electronic key system, the with-vehicle device is when unlocking of the vehicle door performs the normal communication, the when locking the vehicle door by performing the simplified communication.

  According to this configuration, normal communication is performed without simplifying communication when unlocking a vehicle door that requires high security. Further, when the vehicle door is locked, simplified communication is performed because security as high as the unlocking of the vehicle door is not required. Thereby, the power consumption concerning communication can be reduced, ensuring security.

  DESCRIPTION OF SYMBOLS 1 ... Electronic key system, 2 ... Vehicle, 10 ... Electronic key, 11 ... Electronic key control part, 20 ... In-vehicle apparatus, 21 ... In-vehicle control part

Claims (1)

An in-vehicle device that generates a response code by transmitting a challenge code and encrypting the challenge code through an encryption key;
An electronic key that wirelessly transmits an ID code unique to itself and a response code generated by encrypting the received challenge code through an encryption key;
The in-vehicle device, when performing normal communication through transmission and reception of the ID code, the challenge code and the response code with the electronic key, collation of the ID code stored in itself and the received ID code, In the electronic key system that permits switching of the locking / unlocking state of the vehicle door or starting of the engine when it is determined that the verification of the response code generated by itself and the received response code has been established,
When the in-vehicle device determines that the security required for communication with the electronic key is not required as much as the normal communication through the state of the vehicle, the in-vehicle device performs simplified communication with a lower encryption strength than the normal communication. In doing so ,
The in-vehicle device performs the normal communication when starting the engine, and performs the simplified communication when determining whether or not the electronic key is taken out of the vehicle after the engine starts,
Further, the first simplified communication and the second simplified communication are provided as the simplified communication, and the first simplified communication is performed by reducing the length of the challenge code and the response code or the encryption key. The second simplified communication is communication with reduced encryption strength by omitting the challenge code and the response code,
The in-vehicle device performs the normal communication when the vehicle door recognizes that the vehicle door is opened and closed in the engine stop state as the state of the vehicle, and after the normal communication and before the engine start, the first simplified An electronic key system that performs the second simplified communication when performing communication and determining whether or not the electronic key has been taken out of the vehicle after the engine is started .

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