Methods for establishing a secure connection between a vehicle and a user terminal and associated devices

Abstract

The invention relates to a method for initializing a secure connection comprising: - reception, by a control unit (3) of a vehicle (4), of a first secret previously transmitted by a system (1) to a device (2); and - establishment of a secure communication channel between the control unit (3) of the vehicle (4) and a user terminal (5), provided that the first secret and a second secret stored by the user terminal (5) satisfy a predefined condition, in which the control unit (3) of the vehicle (4) receives the first secret from a device (2) via wireless communication requiring proximity between the device (2) and the control unit (3), after the device (2) has received the first secret from the system (1). Abstract figures: Fig. 3

Description

Title of the invention: Methods for establishing a secure connection between a vehicle and a user terminal and associated devices FIELD OF THE INVENTION

[0001] The invention relates to the establishment of a secure connection between two devices, in particular in the automotive field. STATE OF THE ART

[0002] Vehicle manufacturers are launching digital key services (also known as "phone-as-a-key services") to replace traditional keys with a terminal such as a mobile phone. The terminal can be used, for example, to unlock a vehicle door or start the vehicle's engine.

[0003] To perform these functions, the terminal communicates with a vehicle device, generally called an ECU, via a secure channel.

[0004] Before the secure channel is established, a method has been proposed comprising the following steps: a server generates a first secret and a second secret, the server transmits the first secret to the ECU, and the second secret to the terminal. The terminal and the ECU jointly check whether the first secret and the second secret are related by a predefined mathematical relationship. The secure channel is established only in the positive.

[0005] Since the ECU is embedded in a vehicle, the ECU generally receives the first secret via a wireless radio communication network. However, such a solution may prove difficult to implement in the case where the network coverage of the ECU is poor, for example in a dead zone, and / or degraded, for example in an underground garage. Statement of the invention

[0006] An aim of the invention is therefore to set up a secure offline connection between the telecommunications device and the vehicle when the vehicle control unit cannot receive the first secret from the server.

[0007] To this end, the invention provides a method for initializing a secure connection comprising:

[0008] - reception, by a control unit of a vehicle, of a first secret prea reliably transmitted by a system to a device; and

[0009] - establishment of a secure communication channel between the control unit of the vehicle and a user terminal, provided that the first secret and a second secret stored by the user terminal verify a predefined condition,

[0010] wherein the vehicle control unit receives the first secret from the device via wireless communication requiring proximity between the device and the control unit, after the device has received the first secret from the system.

[0011] A method for initializing a secure connection is also provided, comprising:

[0012] - reception, by a device, of a first secret previously transmitted by a system; and

[0013] - transmission by the device of the first secret to a control unit of a vehicle via wireless communication requiring proximity between the device and the vehicle control unit, the vehicle control unit being configured to establish a secure communication channel with a user terminal, provided that the first secret and a second secret stored by the user terminal verify a predefined condition.

[0014] A method for initializing a secure connection is further provided, comprising:

[0015] - transmission, by a system, of a first secret to a device, the device being configured to transmit the first secret to a vehicle control unit via wireless communication requiring proximity between the device and the vehicle control unit; and

[0016] - transmission by the system of a second secret to a user terminal, the user terminal being configured to establish a secure communication channel with the vehicle control unit, provided that the first secret and the second secret verify a predefined condition.

[0017] In the invention, the device acts as a relay in the communication between the server and the vehicle. This allows the vehicle control unit to receive the first secret even when the control unit is located in an area preventing direct radio communications between the server and the control unit, such as an underground garage. Indeed, the device, having previously received the first secret, can transmit this first secret to the vehicle control unit, given their mutual proximity.

[0018] It may be provided that the second secret is transmitted to the user terminal by the system provided that an identifier specific to the device transmitted by the vehicle control unit to the system and a reference identifier specific to the vehicle stored in a database of the system are identical respectively to a first identifier and a second identifier transmitted by the user terminal to the system, the first identifier and the second identifier being previously transmitted by the device to the user terminal by wireless communication requiring proximity between the user terminal and the device.

[0019] It may be provided that the first secret is a password verifier configured to authorize the establishment of the secure communication channel between the vehicle control unit and the user terminal provided that a candidate password transmitted by the user terminal to the vehicle control unit corresponds to the second secret.

[0020] It can be provided that the transmission of the first secret from the device to the vehicle control unit comprises:

[0021] - near field communication (NFC), or

[0022] - an optical reading, by the vehicle control unit, of a pattern representative of the first secret and displayed by the device, the pattern being for example a bar code or a QR code.

[0023] It can be provided that the device is a smart card.

[0024] According to the invention, a control unit for a vehicle is also provided, the control unit comprising:

[0025] - a first communication interface configured to receive a first secret previously transmitted by a system to a device; and

[0026] - a second communication interface configured to establish a communication channel secure communication between the vehicle control unit and a user terminal, provided that the first secret and a second secret stored by the user terminal verify a predefined condition,

[0027] wherein the first communication interface is configured to receive the first secret from the device via wireless communication requiring proximity between the device and the control unit, after the device has received the first secret from the system.

[0028] According to the invention, a device is also provided, such as a smart card, comprising:

[0029] - a memory storing a first secret previously transmitted by a system; and

[0030] - a communication interface configured to transmit the first secret to a control unit of a vehicle via wireless communication requiring proximity between the device and the control unit of the vehicle, the control unit of the vehicle being configured to establish a secure communication channel with a user terminal, provided that the first secret and a second secret stored by the user terminal verify a predefined condition.

[0031] It can be provided that the memory of the device stores a first identifier and a second identifier, and that the communication interface of the device is further configured to:

[0032] - transmitting the first identifier to a control unit of a vehicle and receiving the second identifier transmitted by the vehicle control unit, via wireless communication requiring proximity between the device and the vehicle control unit;

[0033] - transmitting the first identifier and the second identifier to a user terminal via wireless communication requiring proximity between the device and the user terminal.

[0034] It may further be provided that the first identifier may, for example, be an identifier specific to the device and the second identifier may, for example, be an identifier specific to a vehicle.

[0035] A system is further provided comprising:

[0036] - a communication interface configured to transmit a first secret to a device, the device being configured to transmit the first secret to a control unit of a vehicle via wireless communication requiring proximity between the device and the control unit of the vehicle; and

[0037] - a second communication interface configured to transmit a second secret to a user terminal, the user terminal being configured to establish a secure communication channel with the vehicle control unit, provided that the first secret and the second secret satisfy a predefined condition.

[0038] It may be provided that the system comprises a third communication interface configured to receive a device-specific identifier transmitted by the vehicle control unit and a vehicle-specific identifier transmitted by the vehicle control unit. DESCRIPTION OF FIGURES

[0039] We will now present an embodiment of the invention by way of non-limiting example with the support of the drawings in which:

[0040] [Fig.l] schematically illustrates near-field communications between the vehicle control unit and the user terminal;

[0041] [Fig.2] illustrates a map of the exchanges between a system, a device and a vehicle control unit before the vehicle is first started;

[0042] [Fig.3] illustrates a map of the exchanges between the system, the device, the vehicle control unit and the user terminal after the first start of the vehicle; and

[0043] [Fig.4] is a flowchart of an embodiment of the method according to the invention. DETAILED DESCRIPTION OF THE INVENTION Devices

[0044] Referring to [Fig.l], a vehicle 4 comprises an internal reader 6 and a control unit 3.

[0045] The internal reader 6 comprises: - a first communication interface 61 configured to receive data, for example via near-field communication, for example of the NFC type (NFC for “Near Field Communication” in English terminology) or Bluetooth, with a user terminal 5 and / or a device 2; and - a second communication interface 62 configured to transmit data with the control unit 3 of the vehicle 4.

[0046] The first communication interface 61 may for example be located in the passenger compartment 63 of the vehicle, or at the door 64, or both.

[0047] With reference to Figures 2 and 3, the control unit 3 comprises: - a first communication interface 31; - a second communication interface 32; and - a first memory (not shown in the figures).

[0048] The first and second interfaces 31, 32 are configured as transmitters (according to the English terminology “Poller”) and / or as receivers (according to the English terminology “Listener”) in a near-field communication mode, for example NFC (according to the English terminology “NFC reader”) or Bluetooth, respectively with a device 2 and a user terminal 5.

[0049] Those skilled in the art will refer to the following documents NFC Analog Technical Specification 2.1 - NFC Forum, NFC Digital Protocol Technical Specification 2.1 as well as to the document Digital Key Release 3, Technical Specification 1.1.0 - Car Connectivity Consortium to configure and size the first communication interface 31 and the second communication interface 32.

[0050] For example, as a receiver, the first interface 31 is configured to receive from the device 2 a first secret and an identifier specific to the device 2. As a transmitter, the first interface 31 is configured to transmit to the device 2 an identifier specific to the vehicle 4.

[0051] Furthermore, the second communication interface 32 is configured to establish a secure communication channel between the control unit 3 of the vehicle 4 and the user terminal 5. The establishment of the secure channel may for example follow a security protocol of the SPAKE2+ type by means of the first secret transmitted to the control unit 3 of the vehicle 4, for example a password verifier configured to authorize the establishment of the secure channel between the terminal 5 and the control unit 3 of the vehicle 4 provided that a candidate password transmitted by the user terminal 5 to the control unit 3 of the vehicle 4 corresponds to a second secret, for example a pairing password, previously transmitted to the user terminal 5 by a system 1.

[0052] Those skilled in the art will refer to the documents Network Working Group Internet Draft: SPAKE2+, an Augmented SPAKE, draft-bar-cfrg-spake2plus-00, March 9, 2020, and Digital Key Release 3, Technical Specification LEO-Car Connectivity Consortium for setting the establishment of the secure communication channel.

[0053] The control unit 3 of the vehicle 4 may further comprise a third communication interface 33 configured to transmit the identifier specific to the vehicle 4 and the identifier specific to the device 2 to the system 1.

[0054] The memory of the control unit 3 of the vehicle 4 is configured to store data, for example the first secret. In particular, the memory of the control unit 3 of the vehicle 4 is configured to store the password verifier transmitted by the device 2. In addition, the memory of the control unit 3 of the vehicle 4 is configured to store the identifier specific to the vehicle 4 and the identifier specific to the device 2.

[0055] The device 2 may be a smart card comprising at least: - a second memory (not shown in the figures); and - a communication interface 21.

[0056] The communication interface 21 of the device 2 comprises an NFC module, and an antenna coil. The antenna coil has one or more coplanar coaxial windings parallel to the plane of the card, and consequently has a magnetic axis perpendicular to the plane of the card. The communication interface 21 of the device 2 is configured to carry out NFC (near field contactless) communication with an external NFC terminal, for example the user terminal 5 (for example a smartphone in English terminology) via the antenna coil.When the smart card (device 2) and the external NFC terminal (user terminal 5) are placed sufficiently close to each other, the antenna coil of the card is inductively coupled to an antenna coil of the external NFC terminal (user terminal 5), and data can be exchanged using conventional NFC techniques such as those defined by ISO 14443, ISO 15693. For this purpose, the antenna coil of the smart card is associated with passive components (e.g. capacitors) to form an antenna circuit tuned to an operating frequency of the external NFC terminal (user terminal 5), for example 13.56 MHz.

[0057] According to other embodiments, the communication interface 21 may comprise one of the following elements:

[0058] - a Bluetooth module;

[0059] - an electronic module configured to exchange data with the NFC terminal external, for example the user terminal 5, when there is contact between the external terminal and the communication interface 21 according to the ISO7816-2:2017 standard of October 2017 or the ISO7810:2019 standard of December 2019;

[0060] - a pattern, for example a barcode or a QR code (for “Quick response” in Anglo-Saxon terminology), displayed by device 2.

[0061] According to one embodiment, the communication interface 21 of the device 2 is configured to transmit the first secret to the control unit 3 of the vehicle 4 via NFC communication. For example, the communication interface 21 of the device 2 is configured to transmit the password verifier to the control unit 3 of the vehicle 4.

[0062] According to another embodiment, the communication interface 21 of the device 2 is configured to transmit the first secret, for example the password verifier, by optical reading, by the control unit 3 of the vehicle 4, of a pattern representative of the first secret and displayed by the device 2, the pattern being for example a bar code or a QR code.

[0063] The communication interface 21 of the device 2 is further configured to transmit a first identifier to the control unit 3 of the vehicle 4 and receive a second identifier by the control unit 3 of the vehicle 4. The first identifier and the second identifier being, respectively, the identifier specific to the device 2 and the identifier specific to the vehicle 4.

[0064] According to one embodiment, the communication interface 21 of the device 2 is configured to transmit the first identifier and the second identifier to the user terminal 5 by near-field communication. The first identifier being specific to the device 2 and the second identifier being specific to the vehicle 4.

[0065] According to another embodiment, the communication interface 21 of the device 2 is configured to transmit the first identifier and the second identifier to the user terminal 5 by optical reading, by the terminal 5, of a pattern representative of the first identifier and the second identifier and displayed by the device 2, the pattern being for example a bar code or a QR code.

[0066] The memory of the device 2 is configured to store data, for example the first secret. In particular, the memory of the device 2 is configured to store the password verifier transmitted by the communication interface 21 of the device 2 to the control unit 3 of the vehicle 4. In addition, the memory is configured to store the first identifier specific to the device 2 and the second identifier specific to the vehicle 4.

[0067] The user terminal 5 comprises at least: - a third memory (not shown); - a communication interface 51;

[0068] - a communication interface 52; and

[0069] - a communication interface 53;

[0070] The user terminal 5 may be a mobile terminal, for example of the type “smartphone”, or a fixed terminal, for example a computer.

[0071] According to one embodiment, the communication interface 51 of the user terminal 5 is configured to receive the first identifier and the second identifier transmitted by the device 2 by near-field communication, for example of the NFC or Bluetooth type. The first identifier being specific to the device 2 and the second identifier being specific to the vehicle 4.

[0072] According to another embodiment, the communication interface 51 of the terminal 5 is configured to receive the first identifier and the second identifier transmitted by the device 2 by optical reading, by the user terminal 5, of a pattern representative of the first identifier and the second identifier and displayed by the device 2, the pattern being for example a bar code or a QR code.

[0073] The second communication interface 52 of the user terminal 5 is configured to exchange data with the system 1. According to one embodiment, the communication interface 52 of the terminal 5 is configured to send the first identifier and the second identifier to the system 1 by radio communication, for example of the GSM type (for “Global System for Mobile communication” in English terminology) and receive the second secret transmitted by the system 1 by radio communication.

[0074] The third communication interface 53 of the user terminal 5 is configured to exchange data with the control unit 3 of the vehicle 4, by near-field communication, for example of the NFC or Bluetooth type. For example, the third communication interface 53 of the user terminal 5 is configured to transmit the second secret to the control unit of the vehicle 4.

[0075] The communication interfaces 51 and 53 are further configured to exchange data with the control unit 3 of the vehicle 4, and transmit data to the internal reader 6.

[0076] The memory of the user terminal 5 is configured to store data, for example the second secret. In particular, the memory is configured to store the pairing password transmitted by the system 1. In addition, the memory of the user terminal 5 is configured to store the first identifier and the second identifier.

[0077] The user terminal 5 may comprise a computer program product, for example a mobile telephone application, comprising code instructions executed by a processor of the user terminal 5 configured to control the communication interfaces 51, 52, 53 of the user terminal 5 and the third memory of the user terminal 5.

[0078] The first secret and the second secret, for example, respectively, the password verifier and the pairing password, are transmitted by the system 1 including: - a database configured to initially record a reference identifier specific to the vehicle 4, the first and second secrets associated with the reference identifier specific to the vehicle 4, then record the identifier specific to the device 2 and associate it with the reference identifier specific to the vehicle 4, when the identifier specific to the device 2 accompanied by the identifier specific to the vehicle 4 are transmitted by the control unit 3 of the vehicle 4 and the identifier specific to the vehicle 4 corresponds to the reference identifier specific to the vehicle 4 recorded in the database,; and - a server comprising: - a communication interface 11 configured to transmit the first secret to the device 2; and - a second communication interface 12 configured to transmit the second secret to the user terminal 5 provided that there is a correspondence, in the database, between the reference identifiers specific to the vehicle 4 and specific to the device 2 which are stored there, and, respectively, the identifiers specific to the vehicle 4 (second identifier) ​​and specific to the device 2 (first identifier) ​​transmitted by the terminal 5 to the system 1; - a third communication interface 13 configured to receive the identifier specific to the vehicle 4 and the identifier specific to the device 2 transmitted by the control unit 3 of the vehicle 4; and - a fourth communication interface 14 configured to receive the first identifier and the second identifier transmitted by the user terminal 5.

[0079] The system 1 may further comprise several interconnected servers.

[0080] The second secret may be a pairing password that can be recognized by the password checker. Process

[0081] With reference to [Fig.4], a method jointly implemented by the system 1, the control unit 3 of the vehicle 4, the device 2 and the user terminal 5 comprises the following steps.

[0082] During a step E1, the system 1 transmits the first secret to the device 2.

[0083] During a step E2, the device 2 transmits the identifier specific to the device 2 to the control unit 3 of the vehicle 4 and the control unit 3 of the vehicle 4 transmits the identifier specific to the vehicle 4 to the device 2.

[0084] During a step E3, the vehicle 4 is started for the first time.

[0085] During a step E4, the system 1 receives the identifier specific to the device 2 and the vehicle-specific identifier 4 transmitted by the control unit 3 of the vehicle 4 and verifies the existence of a correspondence in the database between the received vehicle-specific identifier 4 and the stored vehicle-specific reference identifier 4 in the database. In case of a match, the device-specific identifier 2 received is stored in the database to associate it with the vehicle-specific reference identifier 4.

[0086] During a step E5, a user of the vehicle 4 sends a request to the system 1 in order to start an attempt to pair the user terminal 5 with the vehicle 4, for example via the application of the automobile manufacturer of the vehicle 4.

[0087] At this stage, the user terminal 5 asks the user to bring the device 2 closer to the user terminal 5, for example by notifying him via the application by a message.

[0088] During a step E6, the device 2 transmits the identifier specific to the device 2 and the identifier specific to the vehicle 4 to the user terminal 5 via wireless communication requiring proximity between the device 2 and the user terminal 5, for example by near field communication (NFC), or optical reading by the user terminal 5 of a pattern representative of the identifiers and displayed by the device 2, the pattern being for example a bar code or a QR code.

[0089] During a step E7, the user terminal 5 transmits the identifier specific to the device 2 and the vehicle's own identifier 4 to the system 1.

[0090] During a step E8, the system 1 verifies the existence of a correspondence, in the database, between the reference identifiers specific to the vehicle 4 and specific to the device 2 which are stored there, and, respectively, the identifiers specific to the vehicle 4 and specific to the device 2 transmitted by the terminal 5 to the system 1 in step E7.

[0091] In the case where the correspondence exists, the system transmits during a step E9 the second secret associated with the pair of identifiers stored in the database to the user terminal 5.

[0092] Then, during a step E10, the device 2 transmits the first secret to the control unit 3 of the vehicle 4 via wireless communication requiring proximity between the device 2 and the control unit 3, for example by near field communication (NFC), or optical reading by the control unit 3 of the vehicle 4 of a pattern representative of the first secret and displayed by the device 2, the pattern being for example a bar code or a QR code.

[0093] It can be provided that the device 2 transmits the first secret to the control unit 3 of the vehicle 4 earlier, for example after the vehicle has started (step E3).

[0094] The first secret may for example be the password verifier and the second secret the pairing password. In this case, the user terminal 5 transmits to the control unit 3 of the vehicle 4 via near field communication (for example Bluetooth or NFC) a candidate password, the password verifier thus authorizing the establishment of the secure communication channel between the terminal 5 and the control unit 3 of the vehicle 4 provided that the candidate password transmitted by the user terminal 5 to the control unit 3 of the vehicle 4 cor responds to the pairing password transmitted by system 1 to user terminal 5.

[0095] If the password verifier gives its authorization, the secure communication channel between the control unit 3 of the vehicle 4 and the user terminal 5 is established during a step Eli.

[0096] During a step El2, the user is invited, for example by receiving a notification on his terminal 5 to pair his terminal 5 with the vehicle 4. He can for example place his terminal 5 near the internal reader 6 of the vehicle 4 to carry out the pairing. By pairing, we mean a procedure for generating, sharing and storing cryptographic keys between the control unit 3 of the vehicle 4 and the user terminal 5, via the secure communication channel, in order to allow the user terminal 5 to be able to interact with the vehicle 4 (for example to allow the user terminal 5 to be able to control different components of a vehicle, for example, opening the doors, or starting the engine).

[0097] The user terminal 5 is paired with the vehicle 4.

[0098] The user can then interact with the various components of the vehicle 4 in near-field communication. For example, he can bring his user terminal 5 or his device 2 close to the handle to unlock the doors of the vehicle 4 and then, when he takes his place in the passenger compartment, he can place his terminal 5 in the internal reader 6 of the vehicle 4 to start the engine.

[0099] In the case where the correspondence does not exist, the system 1 transmits, during a step E81, to the user terminal 5 an error message instead of the second secret, the error message indicating that the user terminal 5 is not authorized to communicate with the vehicle 4, or to initiate the establishment of a secure channel.

Claims

Claims

1. A method for initiating a secure connection comprising: - receiving, by a control unit (3) of a vehicle (4), a first secret previously transmitted by a system (1) to a device (2); and - establishing a secure communication channel between the control unit (3) of the vehicle (4) and a user terminal (5), provided that the first secret and a second secret stored by the user terminal (5) satisfy a predefined condition, wherein the control unit (3) of the vehicle (4) receives the first secret from the device (2) via wireless communication requiring proximity between the device (2) and the control unit (3), after the device (2) has received the first secret from the system (1).

2. A method for initializing a secure connection comprising: - receiving, by a device (2), a first secret previously transmitted by a system (1); and - transmitting by the device (2) the first secret to a control unit (3) of a vehicle (4) via wireless communication requiring proximity between the device (2) and the control unit (3) of the vehicle (4), the control unit (3) of the vehicle (4) being configured to establish a secure communication channel with a user terminal (5), provided that the first secret and a second secret stored by the user terminal (5) satisfy a predefined condition.

3. A method for initiating a secure connection comprising: - transmitting, by a system (1), a first secret to a device (2), the device (2) being configured to transmit the first secret to a control unit (3) of a vehicle (4) via wireless communication requiring proximity between the device (2) and the control unit (3) of the vehicle (4); and - transmitting by the system (1) a second secret to a user terminal (5), the user terminal (5) being configured to establish a secure communication channel with the control unit (3) of the vehicle (4), provided that the first secret and the second secret verify a predefined condition.

4. Method according to any one of claims 1 to 3, in which the second secret is transmitted to the user terminal (5) by the system (1) provided that an identifier specific to the device (2) transmitted by the control unit (3) of the vehicle (4) to the system (1) and a reference identifier specific to the vehicle (4) stored in a database of the system (1) are identical respectively to a first identifier and a second identifier transmitted by the user terminal (5) to the system (1), the first identifier and the second identifier being previously transmitted by the device (2) to the user terminal (5) by wireless communication requiring proximity between the user terminal (5) and the device (2).

5. Method according to one of claims 1 to 4, in which the first secret is a password verifier configured to authorize the establishment of the secure communication channel between the control unit (3) of the vehicle (4) and the user terminal (5) provided that a candidate password transmitted by the user terminal (5) to the control unit (3) of the vehicle (4) corresponds to the second secret.

6. Method according to one of claims 1 to 5, in which the transmission of the first secret from the device (2) to the control unit (3) of the vehicle (4) comprises: - a near field communication (NFC), or - an optical reading, by the control unit (3) of the vehicle (4), of a pattern representative of the first secret and displayed by the device (2), the pattern being for example a bar code or a QR code.

7. Method according to one of claims 1 to 6, in which the device (2) is a smart card.

8. Control unit (3) for a vehicle (4), the control unit (3) comprising: - a first communication interface (31) configured to receive a first secret previously transmitted by a system (1) to a device (2); and - a second communication interface (32) configured to establish a secure communication channel between the control unit (3) of the vehicle (4) and a user terminal (5), provided that the first secret and a second secret stored by the user terminal (5) satisfy a predefined condition, wherein the first communication interface is configured to receive the first secret from the device (2) via wireless communication requiring proximity between the device (2) and the control unit (3), after the device (2) has received the first secret from the system (1).

9. Device (2), such as a smart card, comprising: - a memory storing a first secret previously transmitted by a system (1); and - a communication interface (21) configured to transmit the first secret to a control unit (3) of a vehicle (4) via wireless communication requiring proximity between the device (2) and the control unit (3), the control unit (3) of the vehicle (4) being configured to establish a secure communication channel with a user terminal (5), provided that the first secret and a second secret stored by the user terminal (5) verify a predefined condition.

10. System (1) comprising: - a communication interface (11) configured to transmit a first secret to a device (2), the device (2) being configured to transmit the first secret to a control unit (3) of a vehicle (4) via wireless communication requiring proximity between the device (2) and the control unit (3) of the vehicle (4); and - a second communication interface (12) configured to transmit a second secret to a user terminal (5), the user terminal (5) being configured to establish a secure communication channel with the control unit (3) of the vehicle (4), provided that the first secret and the second secret verify a predefined condition.

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