Method for securing the transmission of the identifier of a portable device for accessing a motor vehicle

Abstract

The invention relates to a method for securing the transmission of the identifier of a portable access device (20) for a motor vehicle (10), said vehicle comprising an electronic control unit (11), said device (20) comprising a control module (21), said method comprising the steps of command, by the management module (21), to send a request for a high-frequency signature and its characteristics, receipt, by the vehicle (10), of the high-frequency signature request, generation, by the vehicle (10), of a high-frequency signature, sending the generated high-frequency signature to the device (20), analysis, by the device (20), of the received high-frequency signature, sending, by the control module (21), of a signal containing an identifier if the high-frequency signature has the expected characteristics, reception, by the vehicle (10), of the sent signal.Identification of the device by the vehicle (10) and activation of a vehicle function (10). Figure for the abbreviation: Figure 1,

Description

Title of the invention: Method for securing the transmission of the identifier of a portable device for accessing a motor vehicle. Technical field

[0001] The present invention relates to the automotive field and more particularly concerns a method for securing the transmission of the identifier of a portable vehicle control device. Previous technique

[0002] For reasons of convenience, an increasing number of motor vehicle functions can be performed remotely by a user using a portable device. Contactless unlocking thus allows a user with a portable access device, such as a key or badge, to unlock the vehicle remotely as they approach.

[0003] This contactless unlocking is achieved through the exchange of radio frequency (RF) waves between the device and the vehicle. Typically, when the vehicle detects the device, it sends a message to the device, which in turn sends back its identifier. Once the vehicle receives the identifier, an onboard electronic control unit commands the unlocking of the doors and windows.

[0004] However, this unlocking method is vulnerable to hacking attempts, particularly so-called "relay" attacks, when the user is away from the vehicle. These attacks consist of recording and retransmitting the signals exchanged between the vehicle and the device to force detection while they are separated, and trigger the transmission of the identifier. Armed with this identifier, a third party can then unlock the vehicle in the user's absence and gain entry to steal items or steal the vehicle itself.

[0005] Several techniques have been developed to enhance the security of radio frequency exchanges.

[0006] For example, the vehicle can measure the strength of the received signal to determine whether the signal is emitted by the user's device or by a third party attempting a relay attack on the vehicle. However, these techniques are complex because the signal strength can vary greatly between legitimate situations, for example, if the user has their device in a pocket, near a metallic object, etc.

[0007] Other techniques involve disabling the vehicle module that analyzes radio frequency waves to protect it from hacking attempts, based in particular on the movement and distance of the user device. However, the Disabling the module is only effective in some cases, and does not work to protect the vehicle in others, for example if the relay attack takes place while the user is moving or before the module goes into standby mode.

[0008] The vehicle module can also record the relative positions of the user device to deduce a user trajectory and determine the legitimacy of the received signals. However, this technique is complex because the module must be able to analyze very different approach trajectories to determine those corresponding to the legitimate user and those resulting from hacking attempts.

[0009] A simple, reliable and effective solution that would at least partially remedy these drawbacks would therefore be advantageous. Description of the invention

[0010] To this end, the invention first relates to a method for securing the transmission of the identifier of a portable access device for a motor vehicle, said vehicle comprising an electronic control unit, a radio frequency antenna module and a high-frequency antenna module, said device comprising a control module, a radio frequency antenna module and a high-frequency antenna module, said control module comprising a memory area in which the identifier of said device is stored, said method comprising the steps of:

[0011] - control, by the device's control module, of the emission, via the module radio frequency antenna of the device, a high-frequency signature request, said high-frequency signature request including the characteristics of said signature,

[0012] - reception, by the electronic control unit, via the antenna module vehicle radio frequency, high-frequency signature request,

[0013] - generation, by the electronic control unit, of a high-frequency signature including the following characteristics,

[0014] - sending to the device, via the vehicle's high-frequency antenna module, the generated high-frequency signature,

[0015] - reception, by the control module, via the high-frequency antenna module of the device, of the high-frequency signature sent,

[0016] - analysis, by the control module, of the received high-frequency signature,

[0017] - when the high-frequency signature has the characteristics sent in the high-frequency signature request, sending, by the control module, via the radio frequency antenna module of the device, of a signal containing the identifier, reception by the electronic control unit, via the vehicle's radio frequency antenna module, of the signal sent, identification of the device by the electronic control unit and activation of a vehicle function once the device is identified.

[0018] The method according to the invention thus makes it possible to secure the transmission of the identifier by the device to the vehicle by implementing a prior exchange of a high-frequency signature request and the high-frequency signature. High-frequency signals have a shorter range compared to other types of radio frequency signals, and thus limit the possibility for a third party to use a interception device to receive and repeat the received signals. The prior exchange also secures the device, because if a fraudulent identifier transmission command is received by the device, it will not transmit the identifier since no high-frequency signature has been received beforehand. This protection also covers the eventuality in which a third party transmits a fraudulent high-frequency signature that does not correspond to any high-frequency signature request sent beforehand.

[0019] Preferably, the electronic control unit temporarily stores the receipt of the high-frequency signature request in its memory and, when identifying the device, only identifies the device if the identifier has been received and the electronic control unit still has the receipt of the high-frequency signature request in its memory. Thus, even if a third party has managed to steal the device identifier, they cannot activate the vehicle's functions without first initiating the exchange of the high-frequency signature request and the high-frequency signature.

[0020] According to another aspect, the invention relates to a method for securing the transmission of the identifier of a portable vehicle access device implemented by the device, said device comprising a control module, a radio frequency antenna module and a high-frequency antenna module, said control module comprising a memory area in which the identifier of said device is stored, said method comprising the steps of:

[0021] - control, by the device control module, of the emission, via the module radio frequency antenna of the device, a high-frequency signature request, said high-frequency signature request including the characteristics of said signature,

[0022] - reception, by the control module, via the high-frequency antenna module of the device, of a high-frequency signature sent,

[0023] - analysis, by the control module, of the received high-frequency signature,

[0024] - when the high-frequency signature has the characteristics sent in the high-frequency signature request, sending, by the control module, via the radio frequency antenna module of the device, of a signal containing the identifier.

[0025] According to another aspect, the invention relates to a method for securing the transmission of an identifier of a portable device for accessing a motor vehicle implemented by the vehicle, said vehicle comprising an electronic control unit, a radio frequency antenna module and a high-frequency antenna module, said method comprising the steps of:

[0026] - reception, by the electronic control unit, via the antenna module vehicle radio frequency, a high-frequency signature request, said high-frequency signature request including the characteristics of said signature,

[0027] - generation, by the electronic control unit, of a high-frequency signature including the following characteristics,

[0028] - sending, via the vehicle's high-frequency antenna module, the high- frequency generated,

[0029] - reception, by the electronic control unit, via the antenna module vehicle radio frequency, of a signal containing the identifier,

[0030] - identification, by the electronic control unit, of the identifier and activation of a vehicle function.

[0031] Advantageously, the vehicle includes a locking system connected to the electronic control unit and the vehicle function activated at the device identification step during the process according to the invention is the unlocking of the vehicle locking system.

[0032] Alternatively, the vehicle function activated at the device identification stage may be engine start, air conditioning activation, etc.

[0033] In a preferred operating mode, the control module starts a timer when the high-frequency signature request is sent, stops the timer when the high-frequency signature is received, compares the measured time with a reference time, and triggers the signature analysis step only if the measured time is less than the reference time. This timer allows for the identification of a legitimate exchange between the vehicle and the user-worn device. If a third party attempts to capture and retransmit the radio frequency signature, the generated delay causes a shift that blocks the process, preventing the fraudulent capture of the identifier.

[0034] Preferably, the values ​​of the high-frequency signature request characteristics are generated randomly each time the method is implemented. Thus, if the high-frequency signature is captured by a third party during an exchange between the vehicle and the device, it cannot be reused later.

[0035] Preferably, the high-frequency signature request is a square wave signal whose characteristics include the number of squares, their duration, and / or their spacing. The high-frequency signature can thus be a PWM (Pulse-Width Modulation) signal. This type of signal is simple to transmit and does not result in excessive current consumption for both the stationary vehicle and the device.

[0036] In a preferred embodiment, the vehicle's high-frequency antenna module and the device's high-frequency antenna module each comprise a high-frequency antenna, the two antennas being resonant with each other. Resonant means that the two antennas transmit and receive signals at the same frequency. Thus, if a third party attempts to use a device that does not have an antenna whose resonant frequency matches that of the vehicle's and the device's resonant antenna, the resulting signal will be severely jammed and therefore difficult to identify and / or use.

[0037] Preferably, the two resonant antennas have a high quality factor, preferably greater than or equal to 80. The high quality factor ensures signal quality over a greater range. Thus, if a third party attempts to use a device with an antenna having a low quality factor to receive the transmitted high-frequency signal, the signal will be severely jammed unless they are very close to the user's device or vehicle.

[0038] Advantageously, the method as presented includes an evaluation of the signal quality during the high-frequency signature analysis step by the control module, which blocks the process if the signal is of poor quality. Thus, the control module detects a fraudulent attempt due to the poor signal quality and prevents the transmission of the identifier.

[0039] The invention also relates to a device comprising a control module, a radio frequency antenna module and a high-frequency antenna module, said control module comprising a memory area in which an identifier is stored and configured to:

[0040] - be connected to the radio frequency antenna module to the high-frequency antenna module frequency in the device,

[0041] - to control the transmission, via the radio frequency antenna module, of a request to high-frequency signature, said high-frequency signature request including the characteristics of said high-frequency signature,

[0042] - receive, via the high-frequency antenna module, a high-frequency signature sent

[0043] - analyze the received high-frequency signature,

[0044] - when the high-frequency signature has the characteristics sent in the high-frequency signature request, send, via the device's radio frequency antenna module, a signal containing the identifier.

[0045] The invention also relates to an electronic control unit configured for:

[0046] - be connected to a radio frequency antenna module and a high-frequency antenna module frequency,

[0047] - receive, via the vehicle's radio frequency antenna module, a request to high-frequency signature, said high-frequency signature request including the characteristics of said signature,

[0048] - generate a high-frequency signature comprising the characteristics,

[0049] - send, via the vehicle's high-frequency antenna module, the high- frequency generated,

[0050] - receive, via the vehicle's radio frequency antenna module, a signal comprising the identifier,

[0051] - identify the identifier and activate a vehicle function.

[0052] The invention also relates to a vehicle comprising an electronic control unit as shown, a radio frequency antenna module and a high-frequency antenna module.

[0053] The invention also relates to a system comprising the vehicle as shown and a portable access device as shown, said system enabling the implementation of the method according to the invention. Brief description of the drawings

[0054] Other features and advantages of the invention will become apparent from the following description. This description is purely illustrative and should be read in conjunction with the accompanying drawings, in which:

[0055] [Fig-1] Fig. 1 schematically illustrates a system comprising a vehicle and a devices configured to implement the process according to the invention.

[0056] [Fig.2] Fig.2 schematically illustrates one embodiment of the process according to the invention. Description of the implementation methods

[0057] Fig. 1 represents a system 1 implementing the method of securing the transmission of the identifier of a portable access device 20 to a motor vehicle 10.

[0058] System 1

[0059] As shown in [Fig.1], the system 1 comprises a vehicle 10 and a device 20, carried by a user of the vehicle 10.

[0060] Vehicle 10

[0061] The vehicle 10 includes an electronic control unit 11, a radio frequency antenna module 12, a high-frequency antenna module 13 and a locking system 14.

[0062] In a manner known per se, the vehicle 10 comprises a plurality of antennas intended to regularly emit detection signals to detect the presence of the device 20 in the vicinity of the vehicle 10. These antennas are not shown in the figures for reasons of clarity.

[0063] These detection signals are low-frequency type signals, around 100 kHz, emitted regularly.

[0064] Electronic control unit 11

[0065] The electronic control unit 11 is configured to be connected to the radio frequency antenna module 12, the high-frequency antenna module 13 and the locking system 14.

[0066] The electronic control unit 11 is configured to receive, via the radio frequency antenna module 12 of the vehicle 10, a high-frequency signature request, said high-frequency signature request including the characteristics of said signature.

[0067] The electronic control unit 11 is configured to generate a high-frequency signature comprising the characteristics, and to send it, via the high-frequency antenna module 13 of the vehicle 10, the generated high-frequency signature.

[0068] The electronic control unit 11 can send the high-frequency signature multiple times to ensure complete reception.

[0069] Advantageously, the electronic control unit 11 can decrypt the high-frequency signature request if the signature request has been previously encrypted by the control module 21, and encrypt the high-frequency signature to be issued.

[0070] The electronic control unit 11 is configured to keep memory of the receipt of the high-frequency signature request and / or the generation of the high-frequency signature within a limited time.

[0071] The electronic control unit 11 is configured to receive, via the radio frequency antenna module 12 of the vehicle 10, a signal containing an identifier.

[0072] The electronic control unit 11 is configured to identify the identifier.

[0073] The electronic control unit 11 is configured to send a signal to the system locking 14.

[0074] In addition or as an alternative, the electronic control unit 11 is configured to send an activation signal for another function of the vehicle 10, for example to start the engine of the vehicle 10 or to activate the air conditioning.

[0075] Radio frequency antenna module 12

[0076] The radio frequency antenna module 12 of the vehicle 10 allows the transmission and reception of radio frequency signals between 200 MHz and 500 MHz, preferably between 300 MHz and 450 MHz.

[0077] The radio frequency antenna module 12 of the vehicle 10 allows radio frequency signals to be sent to the device 20 worn by the user of the vehicle 10.

[0078] The radio frequency antenna module 12 of the vehicle 10 is configured to receive radio frequency signals emitted by the device 20 worn by the user.

[0079] High-frequency antenna module 13

[0080] The high-frequency antenna module 13 includes a resonant antenna 13A.

[0081] The high-frequency antenna module 13 is configured to emit a signal radio frequency in squares to the high-frequency antenna module 23 of device 20.

[0082] The radio frequency signal is emitted in the high-frequency range, i.e. between 3 MHz and 30 MHz.

[0083] Resonant antenna 13A

[0084] The resonant antenna 13A is the electronic component that enables the radio frequency signal to be emitted.

[0085] The resonant antenna 13A has a high quality factor, preferably greater than or equal to 80.

[0086] The resonant antenna 13A is configured to receive a radio frequency signal at a precise frequency, for example 14 MHz, corresponding to the resonant frequency of the resonant antenna 23A present in the high-frequency antenna module 23 of the device 20.

[0087] Locking system 14

[0088] The locking system 14 allows the opening of the vehicle's doors 10 to be locked and unlocked according to the user's commands.

[0089] When the locking system 14 receives the appropriate identifier, the locking system 14 triggers the unlocking of the opening of the vehicle 10 doors.

[0090] A user can then open a door of the vehicle 10 to get inside.

[0091] The locking system 14 can be the target of attacks by malicious third parties who would like to fraudulently gain entry into the vehicle 10.

[0092] Device 20

[0093] The user has device 20 on him. Device 20 allows the vehicle 10 to be unlocked by sending an identifier.

[0094] The device 20 may be present on the key of the vehicle 10, or on a separate accessory.

[0095] The device 20 includes a control module 21, a radio frequency antenna module 22 and a high-frequency antenna module 23.

[0096] In a manner known per se, the device 20 is configured to receive detection signals emitted by the vehicle 10.

[0097] Control Module 21

[0098] The control module 21 includes a memory area in which is stored the identifier enabling the opening of the vehicle's doors 10.

[0099] The control module 21 is configured to be connected to the radio frequency antenna module 22 of the device 20 and to the high-frequency antenna module 23 of the device 20.

[0100] The control module 21 is configured to control the transmission, via the radio frequency antenna module 22, of a high-frequency signature request.

[0101] The high-frequency signature request includes the characteristics of said signature.

[0102] Preferably, the high-frequency signature is a square wave signal, or a PWM (Pulse-Width Modulation) signal whose characteristics include the number of squares, their duration and / or their spacing.

[0103] For example, the expected high-frequency signature characteristics may be "4 10ms slots spaced 50ms apart".

[0104] The characteristics of the high-frequency signature are generated randomly so that from one use to another, the high-frequency signature is unique.

[0105] Advantageously, the control module 21 can encrypt the high-frequency signature request in order to reduce the risk of it being intercepted.

[0106] The control module 21 is configured to receive, via the high-frequency antenna module 23, a sent high-frequency signature.

[0107] In the event that the high-frequency signature sent by vehicle 1 is encrypted, the control module 21 is configured to decrypt the encrypted high-frequency signature.

[0108] The control module 21 is configured to analyze the received high-frequency signature by comparing the characteristics of the received high-frequency signature with those of the request issued by the device 20.

[0109] The control module 21 is configured to also take into account the quality of the signal including the high-frequency signature.

[0110] The control module 21 is configured to send, via the radio frequency antenna module 22 of the device 20, a signal containing the identifier.

[0111] The control module 21 is configured to have a reference time in memory, to start and stop a time counter and to compare the value of the time counter when it is stopped with the stored reference time.

[0112] Radio frequency antenna module 22

[0113] The radio frequency antenna module 22 of the device 20 allows the transmission and reception of radio frequency signals between 200 MHz and 500 MHz, preferably between 300 MHz and 450 MHz.

[0114] The radio frequency antenna module 22 of the device 20 is configured to send a radio frequency signal to the locking system 14 of the vehicle 10 including the identifier enabling the unlocking of the openings.

[0115] High-frequency antenna module 2 3

[0116] The high-frequency antenna module 23 includes a resonant antenna 23A.

[0117] The high-frequency antenna module 23 is configured to receive a signal radio frequency in a square wave emitted by the high-frequency antenna module 23 of vehicle 10.

[0118] The radio frequency signal is emitted in the high-frequency range, i.e. between 3 MHz and 30 MHz.

[0119] Resonant antenna 2 3 A

[0120] The resonant antenna 23A is the electronic component that enables the radio frequency signal to be received.

[0121] The resonant antenna 23A has a high quality factor, preferably greater than or equal to 80.

[0122] The resonant antenna 23A is configured to receive a radio frequency signal at a precise frequency, for example 14 MHz, corresponding to the resonant frequency of the resonant antenna 13A present in the high-frequency antenna module 13 of the vehicle 10.

[0123] The high quality factor and the precise resonant frequency ensure that the high-frequency signals emitted by the high-frequency antenna module 13 and received by the high-frequency antenna module 23 have a high signal-to-noise ratio at a distance of about 2 meters.

[0124] Example of implementation

[0125] In a manner known per se, after the user exits the vehicle 10, the locking system 14 blocks the openings of the vehicle 10 to prevent intrusion.

[0126] In order to detect the return of the user, the vehicle 10 periodically emits detection signals with a range of a few meters, in order to detect the device 20 worn by the user.

[0127] When the user approaches the vehicle 10, the device 20 receives these radio frequency detection signals.

[0128] The method according to the invention begins when the device 20 has received the detection signals emitted by the vehicle 10 and is therefore at a predetermined distance from the vehicle 10.

[0129] In a first step El, the control module 21 of the device 20 generates a high-frequency signature request.

[0130] This query includes the values ​​of the expected high-frequency signature characteristics.

[0131] Preferably, the expected high-frequency signature is a square wave signal or a PWM signal and its characteristics include the number of squares, their duration and / or their spacing.

[0132] During step El, the control module 21 also activates a timer.

[0133] Advantageously, control module 21 encrypts the high-frequency signature request.

[0134] In a second step E2, the high-frequency signature request is transmitted to the radio frequency antenna module 22 of the device 20 which emits it as a radio frequency signal.

[0135] In a third step E3, the high-frequency signature request is received by the radio frequency antenna module 12 of the vehicle 10.

[0136] In a fourth step E4, the radio frequency antenna module 12 sends the high-frequency signature request to the electronic control unit 11.

[0137] Advantageously, the electronic control unit 11 decrypts the high-frequency signature request if it has been previously encrypted by the control module 21.

[0138] In a step E5, the electronic control unit 11 generates a high-frequency signature whose characteristics correspond to those of the received high-frequency signature request.

[0139] In a step E6, the high-frequency signature is transmitted to the high-frequency antenna module 13 of the vehicle 10. The high-frequency signature is then emitted as a high-frequency signal by the resonant antenna 13A.

[0140] In a step E7, the high-frequency signature is received by the high-frequency antenna module 23 of the device 20.

[0141] The reception of the high-frequency signature is carried out by the resonant antenna 13A. This resonant antenna 13A resonates at a precise frequency corresponding to the resonant frequency of the resonant antenna 23A of the device 20.

[0142] Thus the high-frequency signature information received by device 20 is complete and of high quality because the two resonant antennas 13A, 23A have a high quality factor.

[0143] The high quality factor of the 13A, 23A resonant antennas allows a greater range, to about 2 meters, of high-frequency signals at the frequency of the 13A, 23A resonant antennas. Outside this precise frequency, the high-frequency signals would have a much shorter range, on the order of a few centimeters.

[0144] Thus, high-frequency signals have a shorter range than radio-frequency signals emitted and received by radio-frequency antenna modules 12, 22. A third parties must therefore be in close proximity to device 20 and / or vehicle 10 if they wish to capture the high-frequency signature, which prevents them from being discreet.

[0145] Furthermore, if the third party does not use a resonant antenna at the correct frequency corresponding to those of the resonant antennas 13A, 23A, it must also approach within a few centimeters of the vehicle 10 or the device 20 in order to be able to intercept the exchanges of high-frequency signals.

[0146] In a step E8, the control module 21 receives, via the high-frequency antenna module 23 of the device 20, the high-frequency signature.

[0147] Upon receiving the high-frequency signature, the control module 21 stops in a step E9 the time counter engaged during step El and compares it with the stored reference time.

[0148] If a third party attempts to capture the high-frequency signature via a relay attack, the delay between the transmission of the high-frequency signature request and the reception of the high-frequency signature will be longer than during a legitimate exchange. A longer delay will therefore indicate a fraudulent attempt.

[0149] In a step E10, the control module 21 analyzes the received high-frequency signature by comparing its characteristics with those corresponding to the request generated in step E5.

[0150] The analysis performed by the control module 21 also relates to the quality of the signal composing the high-frequency signature. Due to the resonant antennas 13A and 23A, the expected signal is of high quality, i.e., the signal contains little noise compared to the "useful" signal. If a third party attempts to capture the high-frequency signature using an antenna that does not correspond to the resonant frequency of the resonant antenna 23A, the signal will be severely degraded and will therefore indicate a fraudulent attempt.

[0151] If the characteristics match, the control module 21 generates in a step El 1 a signal including the identifier and sends it to the radio frequency antenna module 22.

[0152] In a step E12, the radio frequency antenna module 22 emits a radio frequency signal including the identifier.

[0153] In a step E13, the signal including the identifier is received, via the radio frequency antenna module 12 of the vehicle 10, by the electronic control unit 11.

[0154] During this step, the electronic control unit 11 checks its memory to see if a high-frequency signature request and / or high-frequency signature generation has been previously received. If no such request or generation has been received in memory, a fraudulent attempt is detected and the electronic control unit 11 does not send a signal to the locking system 14.

[0155] If there is a reception and / or a generation in memory, the electronic control unit 11 sends, in a step E14, to the locking system 14 a signal including the identifier, which triggers the unlocking of the vehicle 10 openings.

[0156] Thus the user can open one of the vehicle's doors 10 upon arrival without having to perform any additional action.

[0157] Since the emission of the signal including the identifier is triggered when the device 20 worn by the user is near the vehicle 10, a possible third party who would seek to fraudulently capture this identifier has less opportunity to place a capture device.

[0158] Furthermore, the presence of a prior high-frequency signature exchange conditions the issuance of the identifier.

[0159] If a third party sends a signal to device 20 seeking to automatically trigger the sending of the identifier, device 20, not having previously received a high-frequency signature, will not emit the identifier.

[0160] Similarly, if a third party who has managed to capture the identifier sends this identifier to the vehicle 10 in the absence of prior high-frequency signature transmission, the electronic control unit 11 can thus block the signal and not send it to the locking system 14, preventing the opening of the doors.

[0161] Finally, a third party may attempt to carry out a relay attack by causing the sending of a high-frequency signature request and intercepting this request to retransmit it near vehicle 10 to capture the high-frequency signature.

[0162] On the one hand, if the third party does not have a resonant antenna at the correct frequency, the signal will be of inferior quality and will not allow the sending of the identifier to be triggered.

[0163] On the other hand, the capture and retransmission would cause a latency in the reception of the high-frequency signature which the control module 21 can interpret as a fraudulent attempt, thus blocking the sending of the identifier.

Claims

Demands

1. A method for securing the transmission of the identifier of a portable access device (20) for a motor vehicle (10), said vehicle (10) comprising an electronic control unit (11), a radio frequency antenna module (12) and a high-frequency antenna module (13), said device (20) comprising a control module (21), a radio frequency antenna module (22) and a high-frequency antenna module (23), said control module (21) comprising a memory area in which the identifier of said device (20) is stored, said method comprising the steps of: - command (E1), by the control module (21) of the device (20), to transmit, via the radio frequency antenna module (22) of the device (20), a high-frequency signature request, said high-frequency signature request comprising the characteristics of said signature, - reception (E4), by the unit electronic control (11),via the vehicle's (10) radio frequency antenna module (22), the high-frequency signature request, - generation (E5), by the electronic control unit (11), of a high-frequency signature containing the characteristics, - transmission (E6) to the device (20), via the vehicle's (10) high-frequency antenna module (13), of the generated high-frequency signature, - reception (E8), by the control module (21), via the device's (20) high-frequency antenna module (13), of the transmitted high-frequency signature, - analysis (E10), by the control module (21), of the received high-frequency signature, - when the high-frequency signature has the characteristics sent in the high-frequency signature request, transmission (E11), by the control module (21), via the device's (20) radio frequency antenna module (22), of a signal containing the identifier, received (E13) by the electronic control unit (11),via the vehicle's (10) radio frequency antenna module (12), the signal sent, identification of the device (20) by the electronic control unit (11) and activation (E14) of a vehicle function (10) once the device (20) is identified.

2. A method according to the preceding claim, wherein the vehicle (10) includes a locking system (14) connected to the electronic control unit (11) and wherein the function of the vehicle (10) activated at the device identification step (20) is the unlocking of the locking system (14) of the vehicle (20).

3. A method according to any one of the preceding claims, wherein the control module (21) starts a time counter when sending the high-frequency signature request, stops the time counter when receiving the high-frequency signature, compares (E9) the time thus measured with a reference time and triggers the signature analysis step (E10) only if the measured time is less than the reference time.

4. A method according to any one of the preceding claims, wherein the values ​​of the high-frequency signature query features are generated randomly at each implementation of the method.

5. A method according to any one of the preceding claims, wherein the high-frequency signature request is a square wave signal whose characteristics include the number of squares, their duration and / or their spacing.

6. A method according to any one of the preceding claims, wherein the high-frequency antenna module (13) of the vehicle (10) and the high-frequency antenna module (23) of the device (20) each comprise a high-frequency antenna (13A, 23A), the two antennas (13A, 23A) being resonant with each other.

7. Device (20) comprising a control module (21), a radio frequency antenna module (22) and a high-frequency antenna module (23), said control module (21) comprising a memory area in which an identifier is stored and configured to: - be connected to the radio frequency antenna module (22) and the high-frequency antenna module (23) in the device (20), - command the transmission, via the radio frequency antenna module (22), of a high-frequency signature request, said high-frequency signature request comprising the characteristics of said high-frequency signature, - receive, via the high-frequency antenna module (23), a transmitted high-frequency signature, - analyze the received high-frequency signature, - when the high-frequency signature has the characteristics sent in the high-frequency signature request, send, via the radio frequency antenna module (22) of the device (20), a signal containing the identifier.

8. Electronic control unit (11) configured to: - be connected to a radio frequency antenna module (12) and a high-frequency antenna module (13), - receive, via the radio frequency antenna module (12) of the vehicle (10), a high-frequency signature request, said high-frequency signature request including the characteristics of said signature, - generate a high-frequency signature including the characteristics, - send, via the high-frequency antenna module (13) of the vehicle (10), the generated high-frequency signature, - receive, via the radio frequency antenna module (12) of the vehicle (10), a signal including the identifier, - identify the identifier and activate a function of the vehicle (10).

9. Vehicle (10) comprising an electronic control unit (11) according to the preceding claim, a radio frequency antenna module (12) and a high-frequency antenna module (13).

10. System (1) comprising a vehicle (10) according to the preceding claim and a device (20) according to claim 7.

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