JP5400407B2 - Keyless entry device - Google Patents

Description

  The present invention relates to a keyless entry device that locks and unlocks a door of a vehicle by performing wireless communication between a vehicle-side device and a portable device, and more particularly to a keyless entry device that can prevent unlocking by a relay attack.

  2. Description of the Related Art Conventionally, a keyless entry device that performs wireless communication between a vehicle-side device provided in a vehicle and a portable device carried by a user and locks / unlocks the door of the vehicle is known. In recent years, when a portable device approaches the vehicle, communication is automatically performed between the vehicle-side device and the portable device, and if the ID that is uniquely set for each portable device is authenticated, A passive keyless entry device that performs locking and unlocking operations is also known.

  In wireless communication in a passive keyless entry device, an LF signal (several hundreds KHz) with a narrow communication range is transmitted from the vehicle, while an RF signal (426 to 429 MHz) with a wide communication range is transmitted from the portable device. The LF signal reaches only within a range of several meters from the vehicle, while the RF signal reaches a range of several tens to several hundreds of meters from the portable device.

  In a passive keyless entry device, there is a concern that a relay attack using a repeater that exploits the mechanism is performed. The relay attack prepares two repeaters, one repeater is arranged in the vicinity of the vehicle to receive the LF signal from the vehicle, and the signal from one repeater that has received the LF signal is received as an RF signal. The other repeater placed at a remote position receives the RF signal, and the other repeater transmits the received signal as an LF signal, and has a portable device in the vicinity of the other repeater. When a person approaches, the portable device receives an LF signal from the repeater and transmits an RF signal, which is received by the vehicle and unlocked without the intention of the vehicle owner.

  Various methods have been considered to detect and prevent such relay attacks. As a passive keyless entry device corresponding to a relay attack, for example, there are devices described in Patent Documents 1 to 3.

JP 2001-342758 A JP 2008-240315 A JP 2008-12787A

  The system of Patent Document 1 is provided with a plurality of antennas on the vehicle side and attempts to detect that a relay attack has been performed by detecting the direction of a signal. However, a plurality of antennas must be provided. However, there is a problem that the number of parts increases and the processing becomes complicated.

  The system of Patent Document 2 performs communication while changing the frequency between the vehicle and the portable device, and detects that a relay attack has been performed when the signal strength at any frequency is small. There is a problem that it is necessary to designate a communication frequency and transmit a signal at the frequency, and the configuration for communication is complicated.

  The system of Patent Document 3 is provided with a wireless device at a fixed position, and detects the presence or absence of a relay attack by detecting the signal strength between the wireless device and the vehicle side device. There is a problem that an apparatus is necessary and costs are high, and countermeasures are difficult in other places.

  In any case, the conventional keyless entry device has a problem that the configuration for detecting the relay attack becomes complicated.

  The present invention has been made in view of the above problems, and an object thereof is to provide a keyless entry device capable of detecting a relay attack with a simple configuration.

In order to solve the above-described problem, a keyless entry device according to the present invention includes a vehicle-side transmission unit provided in a vehicle and connected to a transmission antenna that transmits a request signal, and a vehicle-side reception unit that receives an answer signal. In a keyless entry device having a vehicle-side device, a portable device including a portable device receiver that receives the request signal, and a portable device transmitter that transmits an answer signal,
The vehicle-side device includes a vehicle-side control unit that performs predetermined control when an answer signal from the portable device is authenticated, and the portable device detects a strength of a request signal transmitted from a transmission antenna of the vehicle-side device. Equipped with a machine control unit,
The vehicle-side control unit has an intensity level for a request signal transmitted from the transmission antenna.
To the vehicle-side transmission unit controls so as to change, by the portable controller which detects the presence or absence of a change in intensity corresponding to the intensity variation of the request signal in the received signal, relay
-It is characterized by determining whether or not an attack is being performed .

  The keyless entry device according to the present invention does not transmit an answer signal when the portable device control unit does not detect a change in strength corresponding to a change in strength of the request signal in the received signal. If detected, an answer signal is transmitted to the portable device transmission unit.

  Furthermore, in the keyless entry device according to the present invention, the vehicle-side control unit causes the vehicle-side transmission unit to transmit a signal including information as a request signal and an intensity measurement signal, and the intensity measurement signal is stepwise. It is characterized by a change in strength.

  According to the keyless entry device according to the present invention, the vehicle-side device includes a vehicle-side control unit that performs predetermined control when the answer signal from the portable device is authenticated, and the portable device transmits a request transmitted from the transmission antenna of the vehicle-side device. A portable device control unit that detects the strength of the signal is provided, the vehicle side control unit controls the vehicle side transmission unit so that the strength of the request signal transmitted from the transmission antenna changes, and the portable device control unit performs a request in the received signal. By detecting the presence or absence of an intensity change corresponding to the signal intensity change, a relay attack device that does not detect a signal intensity change transmits only a signal of a certain intensity, so the intensity corresponding to the intensity change of the request signal in the received signal If there is no change, that is, there is no change, or there is little change compared to the change in the transmission strength of the request signal If not, it can be determined that relay attack is being performed, it is possible to reliably prevent the relay attack with a simple configuration.

  Further, according to the keyless entry device according to the present invention, the portable device control unit does not transmit the answer signal when the received signal does not detect the intensity change corresponding to the intensity change of the request signal, If detected, an answer signal is transmitted to the portable device transmission unit, so that the unlocking operation in the vehicle can be reliably prevented when a relay attack is detected.

  Furthermore, according to the keyless entry device according to the present invention, the vehicle-side control unit causes the vehicle-side transmission unit to transmit a signal including information and an intensity measurement signal as a request signal, and the intensity measurement signal is gradually increased in intensity. By changing the intensity, it is possible to easily transmit an intensity measurement signal whose intensity changes, and to reliably detect the intensity change in the portable device.

It is a schematic diagram of the keyless entry device in this embodiment. It is a block diagram of a keyless entry device and a relay attack device. It is a chart figure of the signal transmitted from a vehicle side device. It is a chart figure of the received data when the request signal containing the signal for intensity | strength measurement is received with the portable device directly from the vehicle side apparatus. It is a chart figure of the received data in case a portable machine receives the request signal from the vehicle side apparatus via a relay attack apparatus.

  Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic diagram of a keyless entry device according to this embodiment. The keyless entry device according to the present embodiment locks or unlocks the door 1a of the vehicle 1. The vehicle-side device 2 is provided on the vehicle 1, the user carries the portable device 3, and the vehicle-side device. Wireless communication is performed between the mobile phone 3 and the portable device 3 to perform authentication, locking / unlocking commands, and the like. The vehicle-side device 2 has a plurality of transmission antennas 15 at various locations of the vehicle 1, and a request signal is transmitted from each transmission antenna 15 to the portable device 3.

  In this embodiment, when the user who has the portable device 3 approaches the vehicle 1 and presses the request switch 16 provided in the vehicle 1, the vehicle-side device 2 transmits a request signal, and the portable device 3 makes a request. When the signal is received, communication such as authentication is performed between the vehicle side device 2 and the portable device 3, and the vehicle side device 2 unlocks the door 1a when the authentication is performed. The request signal is composed of a low-frequency LF signal and reaches only a range of several meters from the vehicle side device 2. Therefore, communication is not performed between the portable device 3 and the vehicle side device 2 unless the user is in a state of approaching the vicinity of the vehicle 1. Further, in the keyless entry device of the present embodiment, even when a relay attack device is installed around the vehicle 1 and at a remote position with malicious intent, the mobile device 3 detects it and establishes a relay attack. You can avoid it.

  Next, the structure of the vehicle side apparatus 2 and the portable device 3 is demonstrated. FIG. 2 shows a block diagram of the keyless entry device and the relay attack device. As shown in this figure, the vehicle-side device 2 includes a vehicle-side receiver 10 that receives an answer signal from the portable device 3, a vehicle-side transmitter 11 that transmits a request signal to the portable device 3, and an answer signal. And a vehicle-side control unit 12 that performs various controls when the request switch 16 is pressed. An RF signal is used as the answer signal from the portable device 3.

  The vehicle-side control unit 12 has a memory 13 that stores information necessary for control such as V-ID (V-ID), which is a vehicle-specific identification code, and IDs of a plurality of portable devices that can operate one vehicle. It is connected. The vehicle-side receiving unit 10 is connected to a receiving antenna 14 for receiving an answer signal, and the vehicle-side transmitting unit 11 is connected to a transmitting antenna 15 for transmitting a request signal.

  If each structure of the vehicle side apparatus 2 is seen in detail, the vehicle side receiving part 10 will demodulate an RF signal so that the answer signal received by the receiving antenna 14 can be read by the vehicle side control part 12. Have. Specifically, an RF filter 30 and an RF amplifier 31 that filter and amplify an RF signal before demodulation, a mixer 33 connected to a UHF local oscillator 32 that oscillates a modulation signal, and filtering on a modulated intermediate frequency signal An IF filter 34 and an IF amplifier 35 that perform amplification, and an IF detection circuit 36 that uses a modulated signal as a demodulated signal.

  On the other hand, the vehicle side transmission part 11 has a structure which modulates so that the signal from the vehicle side control part 12 can be transmitted as LF signal. That is, it has a mixer 38 to which an LF oscillator 37 that receives a signal from the vehicle-side controller 12 and oscillates a modulation signal is connected, and an LF amplifier 39 that amplifies the modulated LF signal.

  The portable device 3 includes a portable device receiver 20 that receives a request signal from the vehicle-side device 2, a portable device transmitter 21 that transmits an answer signal to the vehicle-side device 2, and various types of signals when receiving a request signal. It has the portable device control part 22 which performs control, and the memory 23 which memorize | stored ID, V-ID, etc. which were set to the own machine. A reception antenna 24 and a transmission antenna 25 are connected to the portable device receiver 20 and the portable device transmitter 21, respectively.

  The portable device control unit 22 is an intermittent reception state in which the sleep state where the power consumption is substantially zero and the receivable state are switched by a wake-up signal included in the request signal from the vehicle-side device 2 received by the portable device reception unit 20. Switches to a normal state in which the receivable state continues. In addition, the portable device control unit 22 performs various operations based on commands included in the request signal. Furthermore, the portable device control unit 22 can detect the intensity of the signal received by the receiving antenna 24.

  Looking at each configuration of the portable device 3 in more detail, the portable device receiving unit 20 has a configuration for demodulating the LF signal so that the request signal received by the receiving antenna 24 can be read by the portable device control unit 22. doing. Specifically, an LF amplifier 40 that amplifies the LF signal before demodulation and an LF detection circuit 41 that uses the modulation signal as a demodulated signal are provided.

  On the other hand, the portable device transmission unit 21 has a configuration for modulating the signal from the portable device control unit 22 so as to be transmitted as an RF signal. That is, it has a mixer 43 to which a UHF oscillator 42 that receives a signal from the portable device control unit 22 and oscillates a modulation signal is connected, and an RF amplifier 44 that amplifies the modulated RF signal.

  Next, the configuration of the relay attack device will also be described. The relay attack device includes a first repeater 50 disposed in the vicinity of the vehicle 1 and a second repeater 51 disposed at a position separated from the vehicle 1, and performs wireless communication therebetween. The first repeater 50 includes an LF antenna 60 that receives a request signal including an LF signal from the vehicle 1, an LF amplifier 61 that amplifies the LF signal, and an LF detection circuit 62 that demodulates the signal. Let the signal be the demodulated signal.

  The first repeater 50 includes a mixer 64 to which a UHF oscillator 63 that oscillates a modulation signal is connected and an RF amplifier 65 that amplifies the RF signal in order to modulate the demodulated signal as an RF signal. The modulated RF signal is transmitted from the RF transmission antenna 66.

  The second repeater 51 includes an RF antenna 70 that receives the RF signal from the first repeater 50, an RF filter 71 and an RF amplifier 72 that perform filtering and amplification of the received signal, and further oscillates a modulation signal. A mixer 74 connected to the UHF local oscillator 73, an IF filter 75 and an IF amplifier 76 for filtering and amplifying the modulated intermediate frequency signal, and an IF detection circuit 77 using the modulated signal as a demodulated signal. Yes. In addition, in order to transmit the demodulated signal as an LF signal, a mixer 79 connected to the LF oscillator 78, an LF amplifier 80 for amplifying the LF signal, and an LF antenna 81 are provided.

  By having such a configuration, the relay attack device receives a request signal transmitted from the vehicle side device 2 in the vicinity of the vehicle 1 by the first repeater 50 and transmits it as an RF signal over a long distance. Then, the second repeater 51 receives the RF signal from the first repeater 50 and transmits it as an LF signal. When a person with the portable device 3 approaches the second repeater 51, the second repeater 51 The reception antenna 24 of the portable device 3 receives the LF signal from

  Here, when the portable device 3 transmits an answer signal composed of an RF signal by receiving a signal relayed by the relay attack device, the vehicle 1 is unlocked without the user's intention, which is prevented. Therefore, the keyless entry device of the present embodiment has the following configuration.

  First, in the vehicle-side device 2, the vehicle-side control unit 12 causes the vehicle-side transmission unit 11 to transmit a request signal including an LF signal, and the request signal includes an intensity measurement signal whose intensity changes midway. In FIG. 3, the chart figure of the signal transmitted from the vehicle side apparatus 2 is shown. The horizontal direction in FIG. 3 represents time, and the vertical direction represents signal strength.

  As shown in FIG. 3, the request signal transmitted from the vehicle side device 2 includes an information signal composed of a wake-up signal and a command signal, and an intensity measurement signal composed of an RSSI signal transmitted subsequent to the information signal. Yes. The information signal is the same as that used in the conventional keyless entry device. In addition to this, in the present embodiment, the vehicle-side control unit 12 performs control so as to transmit an intensity measurement signal.

  The intensity measurement signal included in the request signal is transmitted so that the intensity changes in a stepwise manner so that the intensity is initially large and becomes smaller than the first. Here, as an example, it is assumed that the first signal level is 10V, the signal level after the intensity is changed is 5V, and has a 2: 1 intensity ratio before and after the change. FIG. 4 shows a chart of received data when the request signal including the intensity measurement signal is received directly from the vehicle-side device 2 by the portable device 3.

  The strength of the request signal received by the portable device 3 varies depending on the distance between the transmission antenna that transmits the request signal and the portable device 3. Since the length of the request signal is very short, the distance between the vehicle side device 2 and the portable device 3 hardly changes while the portable device 3 receives the request signal. Therefore, as shown in FIG. When the request signal from is directly received by the portable device 3, the change in the signal strength of the request signal appears in the received data as it is. That is, the intensity changes stepwise so that the intensity measurement signal received following the information signal has a high intensity at the beginning and a small intensity in the middle. Specifically, when the initial signal level is 50 mV, the signal level changes to 25 mV in the middle, and has a 2: 1 intensity ratio before and after the change.

  The portable device control unit 22 of the portable device 3 detects a time change in strength of the received signal for measuring the strength of the request signal, and if a predetermined strength change is detected as shown in FIG. The transmitter 21 is controlled to transmit an answer signal.

  On the other hand, FIG. 5 shows a chart of received data when the portable device 3 receives a request signal from the vehicle-side device 2 via a relay attack device. The relay attack device receives and demodulates the RF signal from the first repeater 50 by the second repeater 51 as described above, but does not detect the intensity here, so in the transmitted LF signal, The portion of the intensity measurement signal is transmitted as a signal having a constant intensity. For this reason, the strength measurement signal included in the request signal is received by the portable device 3 as a signal having a constant signal strength (the signal level remains 50 mV) from the beginning to the end as shown in FIG.

  The portable device control unit 22 detects a temporal change in the strength of the received request signal strength measurement signal, and if a predetermined strength change is not detected as shown in FIG. In the case of not changing, for example, in the above example, in the case of 1.2: 1 or less, the signal transmission control for the portable device transmission unit 21 is not performed.

  In this way, the vehicle side device 2 transmits an intensity measurement signal whose intensity changes midway in the request signal, and the portable device 3 detects the intensity of the intensity measurement signal included in the received request signal. By transmitting an answer signal only when a predetermined intensity change is detected, a signal from a relay attack device that cannot detect the signal intensity and transmit a signal with the corresponding intensity is used. Since no signal for instructing unlocking is transmitted to the relay attack device, unintentional unlocking by the relay attack device can be prevented. In addition, since the presence or absence of a relay attack can be detected only by detecting the signal strength, the relay attack can be reliably prevented with a simple configuration. Furthermore, since the change in signal strength is made stepwise, the signal transmission can be easily controlled, and the change in strength in the portable device 3 can be reliably detected.

  As mentioned above, although embodiment of this invention was described, application of this invention is not restricted to these embodiment, It can apply variously within the range of the technical idea. For example, in the present embodiment, as the intensity change of the intensity measurement signal, the first is large and small in the middle. However, other patterns may be used, for example, the first may be small and large in the middle. However, the signal intensity may change twice or more. In this embodiment, the signal level is changed in the middle of transmission from the vehicle-side transmission unit. However, each time intermittent transmission is performed, the signal level is switched between a high level and a low level, and this is detected by the portable device 3. Also good. In this case, the intensity of the signal intermittently received a plurality of times is detected for each time, and compared with the previous value, if the change is less than or equal to the predetermined value, it is determined as a relay attack.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Vehicle side apparatus 3 Portable machine 10 Vehicle side receiving part 11 Vehicle side transmission part 12 Vehicle side control part 13 Memory 14 Reception antenna 15 Transmission antenna 16 Request switch 20 Portable machine receiving part 21 Portable machine transmission part 22 Portable machine control part 23 memory 24 receiving antenna 25 transmitting antenna

Claims (3)

A vehicle-side transmitter connected to a transmission antenna that is provided in the vehicle and transmits a request signal;
A keyless device having a vehicle-side device including a vehicle-side receiver that receives an answer signal, a portable device receiver that receives the request signal, and a portable device that includes a portable device transmitter that transmits an answer signal. In the entry device,
The vehicle-side device includes a vehicle-side control unit that performs predetermined control when an answer signal from the portable device is authenticated, and the portable device detects a strength of a request signal transmitted from a transmission antenna of the vehicle-side device. Equipped with a machine control unit,
The vehicle-side control unit has an intensity level for a request signal transmitted from the transmission antenna.
To the vehicle-side transmission unit controls so as to change, by the portable controller which detects the presence or absence of a change in intensity corresponding to the intensity variation of the request signal in the received signal, relay
-A keyless entry device that determines whether or not an attack is being performed . When the portable device control unit does not detect an intensity change corresponding to the intensity change of the request signal in the received signal, it does not transmit an answer signal.
The keyless entry device according to claim 1, wherein an answer signal is transmitted to the portable device transmission unit. The vehicle-side control unit transmits a signal including information and an intensity measurement signal as a request signal to the vehicle-side transmission unit, and the intensity measurement signal changes in intensity stepwise. Item 3. A keyless entry device according to item 1 or 2.

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