Locking and unlocking a communication interface of an electronic device for a motor vehicle

Abstract

In order to lock a communication interface of an electronic device (1) for a motor vehicle, a first identifier (3) is determined which characterizes a hardware component of a computing unit (2) of a production line in which the electronic device (1) was produced or a software component of the computing unit (2). A second identifier (4) is obtained which characterizes the electronic device (1). A first input value for a specified key derivation function is generated by the computing unit (2) on the basis of the first identifier (3), and a second input value for the key derivation function is generated on the basis of the second identifier (4). A key is generated by the computing unit (2) on the basis of the first input value and the second input value using the key derivation function, and the communication interface is locked using the key.

Description

[0001] Locking and unlocking a communication interface of an electronic device for a motor vehicle

[0002] The present invention relates to a method for locking a communication interface of an electronic device for a motor vehicle and a corresponding method for unlocking a communication interface of an electronic device for a motor vehicle. Furthermore, the invention relates to data processing devices and a computer program product.

[0003] Electronic devices for motor vehicles, such as control units or sensors, can have communication interfaces for different purposes.

[0004] For security reasons or to prevent misuse, it may be desirable to disable such communication interfaces once the electronic device is used for normal operation after its manufacture. This may be the case, among other things, with debugging interfaces, such as JTAG interfaces. Such communication interfaces are used during production, for example, for installing software on the electronic device and / or for testing the electronic device's software or for troubleshooting. They are generally not required during normal operation and can therefore be disabled, particularly by means of password protection.

[0005] However, even after production, it may be necessary to access the electronic device via the communication interface, for example, to troubleshoot or modify the software stored on the electronic device, or to save or read other data. To gain access, a user may therefore need to enter the correct password.

[0006] Document US 2017 / 0090909 A1 describes a method for securely writing patch code to a memory of an SoC. A JT AG interface can be used to test the functionality of the SoC. The JT AG interface can be unlocked by the SoC manufacturer entering an interface password. In a password-locked state, values ​​stored in components of the SoC and / or other functionality of the SoC cannot be modified via the JT AG interface. It is an object of the present invention to provide secure access protection for a communication interface of an electronic device for a motor vehicle.

[0007] This object is achieved by the respective subject matter of the independent claims. Advantageous further developments and preferred embodiments are the subject matter of the dependent claims.

[0008] The invention is based on the idea of ​​using a key, also referred to simply as a password, to lock the communication interface. This key is derived, on the one hand, from an identifier assigned to the individual electronic device, but, on the other hand, also from at least one identifier assigned to a hardware component or a software component of a computing unit originating from a production line in which the electronic device was manufactured. The key can be subsequently reconstructed using the former part-specific identifier and the latter production-line-specific identifier. Furthermore, two factors for authentication are implemented, thus increasing security.

[0009] According to one aspect of the invention, a method, for example a computer-implemented method, is specified for blocking a communication interface of an electronic device for a motor vehicle. A first identifier is determined, which identifies a hardware component of a computing unit of a production line in which the electronic device was manufactured, or which identifies a software component of the computing unit. The first identifier is determined, in particular, by means of the computing unit. A second identifier is obtained, in particular, by the computing unit, which identifies the electronic device, in particular uniquely identifies it. By means of the computing unit, a first input value for a predetermined key derivation function is generated depending on the first identifier, and a second input value for the key derivation function is generated depending on the second identifier.By means of the computing unit, a key, in particular a cryptographic key, is generated using the key derivation function depending on the first input value and the second input value. The communication interface is locked using the key, in particular by means of the computing unit, preferably automatically. The first identifier is such that, based on knowledge of the first identifier, the individual hardware or software component identified thereby can be uniquely identified. This can be, for example, a serial number or the like. This applies analogously to the second identifier, so that, based on knowledge of the second identifier, the individual electronic device identified by it can be uniquely identified. Here, too, it can be, for example, a serial number or the like.

[0010] Depending on the embodiment, the first input value can be identical to the first identifier, or the first input value can be derived from the first identifier according to a predetermined rule. In various embodiments, it is also possible to determine, in addition to the first identifier, one or more further first identifiers of the software or hardware component or one or more further hardware or software components of the computing unit, and to derive or calculate the first input value depending on the first identifier and the further identifiers.

[0011] The same applies analogously to the second identifier or the second input value. The second input value can therefore be identical to the second identifier or derived from it, possibly depending on the second identifier and one or more additional second identifiers that identify the electronic device.

[0012] If, in addition to the first identifier, further first identifiers are used for further hardware or software components, the corresponding further hardware or software component can be uniquely identified from the further first identifiers. When one or more further second identifiers are used, these can also enable unambiguous identification of the electronic device, depending on the embodiment. However, this is not necessarily the case, so the further second identifiers, unlike the second identifier, can also be ambiguous. For example, the further second identifiers can contain a model identifier, a production period, a batch number, a production location, and so on of the electronic device.

[0013] The key derivation function, for example, is designed to uniquely derive a corresponding key from two separate input values—in this case, the first input value and the second input value—and is therefore a function of two variables in this case. Accordingly, identical input values ​​always result in the same key. Depending on the implementation, the two input values ​​can also be linked or combined to generate a common input value, and the key derivation function generates the key from the common input value, and is therefore a function of one variable in this case.

[0014] By locking the communication interface using the key, the communication interface is placed in a locked or encrypted state, preventing a user from outside the electronic device from accessing the electronic device via the communication interface. The communication interface can be unlocked, i.e., placed in an unlocked or decrypted state, by entering the key used for locking via the communication interface or another interface of the electronic device.

[0015] The communication interface is, in particular, a communication interface for wired or cable-based communication between an external processing unit and a processor, a memory element, or another component of the electronic device. The communication interface includes, in particular, a hardware interface and / or a software interface.

[0016] The method according to the invention therefore achieves, on the one hand, a high level of security against unauthorized or unwanted access to the electronic device via the communication interface by using the first and second identifiers as two independent factors to generate the key. Using the second identifier ensures that the generated key is uniquely assigned to the individual electronic device. The first identifier is independent of the first identifier in terms of content and, above all, cannot be easily identified by a party potentially accessing the communication interface without authorization. Furthermore, however, with knowledge of the method according to the invention, the key can be reliably reconstructed should the communication interface need to be unlocked.

[0017] Furthermore, the method according to the invention uses the first identifier based on a hardware component or software component of the key generation processing unit that is also used to derive the input values ​​for the key derivation function and to generate the key based thereon. This can further increase security.

[0018] The computing unit is part of the production line in which the electronic device was manufactured. This means, in particular, that steps for manufacturing the electronic device were carried out using the computing unit before the method according to the invention was carried out, for example, for equipping the electronic device with software and / or for testing the software.

[0019] A computing unit can be understood, in particular, as a data processing device that contains a processing circuit. The computing unit can therefore, in particular, process data to perform computing operations. This may also include operations for performing indexed access to a data structure, for example, a look-up table (LUT).

[0020] The computing unit may, in particular, contain one or more computers, one or more microcontrollers, and / or one or more integrated circuits, for example one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), and / or one or more single-chip systems (SoCs). The computing unit may also contain one or more processors, for example one or more microprocessors, one or more central processing units (CPUs), one or more graphics processing units (GPUs), and / or one or more signal processors, in particular one or more digital signal processors (DSPs). The computing unit may also include a physical or virtual network of computers or other of the aforementioned units.

[0021] In various embodiments, the computing unit includes one or more hardware and / or software interfaces and / or one or more memory units.

[0022] A memory unit can be a volatile data memory, for example a dynamic random access memory (DRAM) or a static random access memory (SRAM), or a non-volatile data memory, for example a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM).

[0023] The memory can be designed as an electrically erasable programmable read-only memory (ERAM), as a flash memory or flash EEPROM, as a ferroelectric random access memory (FRAM), as a magnetoresistive random access memory (MRAM), or as a phase-change random access memory (PCRAM).

[0024] According to at least one embodiment of the method for blocking a communication interface, the electronic device is programmed and / or tested at least in part by means of the computing unit before the first identifier is determined and / or the electronic device is software loaded by means of the computing unit before the first identifier is determined and / or the electronic device is troubleshooted by means of the computing unit.

[0025] The steps mentioned can be considered part of the manufacturing of the electronic device. These steps can be performed, at least in part, via the communication interface. In this case, the processing unit is connected to the electronic device via the communication interface and can then remain connected to it, for example, to automatically use the key to lock the communication interface.

[0026] According to at least one embodiment, the communication interface is a debugging interface of the electronic device.

[0027] The invention can be used particularly advantageously with such error-finding interfaces, which are also referred to as debugging interfaces, since these can be used in warranty cases or in the event of errors in the field in order to be able to access the electronic device again after the actual production of the device.

[0028] For example, the debugging interface is standardized according to the industry standard IEEE 1149.1, commonly referred to as JTAG (joint test action group). According to at least one embodiment, the second identifier is determined based on a serial number of the electronic device.

[0029] For example, the second identifier may be identical to the serial number of the electronic device or the second identifier may be determined depending on the serial number together with other part-specific information.

[0030] On the one hand, the serial number of the electronic device is suitable for uniquely identifying the electronic device; on the other hand, the serial number is usually present on the electronic device in electronic or analog form, for example in the form of character strings or an optically or electronically readable code, even after the actual production has been completed.

[0031] According to at least one embodiment, the first identifier is determined depending on a serial number of the hardware component of the computing unit and / or depending on a serial number of the software component of the computing unit.

[0032] The hardware component can be, for example, a mainboard, also known as a mainboard or motherboard, of the computing unit, or a data storage device, such as an SSD drive or an HDD drive, of the computing unit. The software component can be, for example, an operating system or firmware, such as BIOS firmware, of the computing unit.

[0033] The serial number of the hardware component or the software component can, for example, be automatically read and determined by the computing unit itself, so that the security of the process can be further increased.

[0034] According to at least one embodiment, a further first identifier is determined, which identifies a further hardware component of the computing unit or identifies a further software component of the computing unit, in particular by means of the computing unit. The first input value is generated depending on the first identifier and the further first identifier.

[0035] For example, in further embodiments, more than one additional first identifier can be determined and treated accordingly. The first identifier and the additional first identifier(s) can be concatenated or linked via a logical operation, such as an XOR operation, or another rule to generate the first input value. This further increases the security of the key.

[0036] According to at least one embodiment, the key is generated with a bit length of at least 32 bits or at least 64 bits. In this way, a high level of security can be achieved.

[0037] According to at least one embodiment, the electronic device is a sensor for the motor vehicle or an electronic control unit for the motor vehicle.

[0038] The electronic control unit (ECU) can also be designed as a zone control unit (ZCU) or a domain control unit (DCU).

[0039] The sensor can be, for example, an environmental sensor, such as a camera, a lidar system, a radar system or an ultrasonic sensor system, or another sensor for the motor vehicle, such as a steering angle sensor, an acceleration sensor, an inertial measurement unit (IMU), and so on.

[0040] Electronic control units and sensors for motor vehicles are, in some cases, highly safety-critical components that must be reliably protected against unwanted or unauthorized access, while also requiring authorized access after production. This is where the invention is particularly advantageous.

[0041] According to at least one embodiment of the method, at least one historical data set is provided on a storage device. Each historical data set of the at least one historical data set contains corresponding historical identification information for the hardware component or the software component of the computing unit and a manufacturing period associated with the historical identification information. The most recent historical identification information of a most recent historical data set of the at least one historical data set is read from the storage device, in particular by means of the computing unit. A most recent manufacturing period is associated with the most recent historical identification information. A most recent historical first input value is determined based on the most recent historical identification information.

[0042] Using a predetermined hash function, a hash value is generated depending on the first input value, in particular by means of the computing unit. Using the hash function, a further hash value is generated depending on the most recent historical first input value, in particular by means of the computing unit. It is checked, in particular by means of the computing unit, whether the hash value matches the further hash value. If the hash value does not match the further hash value, a further historical data record is stored on the storage device, in particular by means of the computing unit. The further historical data record contains the first input value and a production period assigned to the first input value, or the further historical data record contains the first identifier and a production period assigned to the first identifier.

[0043] In particular, the individual historical data records also contain, as respective historical identification information, either a corresponding historical first input value for the key derivation function or a respective historical first identifier. In the former case, the most recent historical first input value is determined by reading it from the corresponding most recent historical data record. In the latter case, a most recent historical first identifier is read from the corresponding most recent historical data record, and based on this, the most recent historical first input value is determined, in particular as explained above with regard to the generation of the first input value.

[0044] The historical identification information therefore directly or indirectly identifies a historical hardware component or historical software component of the computing unit that was present in the computing unit during the corresponding associated production period. The most recent historical production period can be understood as meaning that no more recent production period is present in the historical data records of the at least one historical data record. The most recent historical data record is then the historical data record containing the most recent production period, and the most recent historical identification information is that contained in the most recent historical data record.

[0045] The storage device is, in particular, a storage device provided externally to the computing unit, which, in particular, represents a secure, access-restricted environment. If the hash value matches the further hash value, this means that the first input value matches the most recent historical first input value or that the first identifier matches the most recent historical first identifier. This therefore means that the hardware component or software component of the computing unit identified by the first identifier or by the first input value matches the software component or hardware component of the computing unit identified by the most recent historical first input value or the most recent historical identifier.

[0046] Accordingly, it can be ensured that when the at least one historical data record on the storage device is used to reconstruct the password for unlocking the communication interface of an electronic device, all required information is stored on the storage device. If this is not the case, i.e., if the hash value does not match the additional hash value, the method for locking the communication interface or for generating the key can be interrupted until the additional historical data record has been saved on the storage device, and the corresponding verification steps can be performed again. When performed again, the hash value will then match the additional hash value.

[0047] In particular, the hash value is generated independently of the most recent historical first input value or only dependent on the first input value. Similarly, the subsequent hash value is generated independently of the first input value or only dependent on the most recent historical input value.

[0048] The hash function is in particular a cryptological hash function, for example an SHA-2 function, in particular an SHA-256 function.

[0049] For applications or application situations that may arise with the method and that are not explicitly described here, it can be provided that, according to the method, an error message and / or a request to enter user feedback is output and / or a default setting and / or a predetermined initial state is set. According to a further aspect of the invention, a method for unlocking a communication interface of an electronic device for a motor vehicle is specified, wherein the electronic device has been locked by means of a method according to the invention for locking a communication interface.According to the method for unlocking the communication interface, at least one historical data set is provided on the storage device, i.e., in particular, the external storage device, wherein each historical data set of the at least one historical data set contains the corresponding historical identification information and the manufacturing period associated with the historical identification information. A device identifier that identifies the electronic device with the communication interface to be unlocked is determined, and, depending on the device identifier, a manufacturing period of the electronic device with the communication interface to be unlocked is determined, in particular by means of a further computing unit.

[0050] Depending on the manufacturing period thus determined, one of the historical data records is selected, in particular the one that corresponds to the manufacturing period determined based on the device identifier, in particular by means of the further computing unit. Depending on the historical identification information of the selected historical data record, a historical first input value is generated for the key derivation function, in particular by means of the further computing unit. Depending on the device identifier, a current second input value is generated for the key derivation function, in particular by means of the further computing unit. Using the key derivation function, a key is reconstructed based on the historical first input value and the current second input value, in particular by means of the further computing unit.The communication interface is unlocked using the reconstructed key, in particular by means of the additional computing unit.

[0051] Regarding the historical identification information, the historical first input values ​​and their relationship to the historical identifiers, reference is made to the procedure for blocking the communication interface described above.

[0052] In this way, a method for unlocking the communication interface is provided in which the key itself does not need to be stored, but can be reliably reconstructed for all production periods and, accordingly, for all relevant electronic devices. For use cases or application situations that may arise during the method and are not explicitly described here, it can be provided that, according to the method, an error message and / or a request for user feedback is issued and / or a default setting and / or a predetermined initial state is set.

[0053] According to a further aspect of the invention, a data processing device is specified which has a computing unit which is configured to carry out a method according to the invention for blocking a communication interface of an electronic device for a motor vehicle.

[0054] According to a further aspect of the invention, a further data processing device comprising a further computing unit is specified, wherein the further computing unit is configured to carry out a method according to the invention for unlocking a communication interface of an electronic device for a motor vehicle.

[0055] According to a further aspect of the invention, a computer program with instructions is specified, wherein the instructions, when executed by a data processing device, in particular a data processing device according to the invention, cause the data processing device to carry out a method according to the invention for blocking a communication interface of an electronic device for a motor vehicle.

[0056] The instructions can be provided, for example, as program code. The program code can be provided, for example, as binary code or assembly code and / or as source code of a programming language, for example, C, and / or as a program script, for example, Python.

[0057] According to a further aspect of the invention, a further computer program with further instructions is specified, wherein the further instructions, when executed by a further data processing device, in particular a further data processing device according to the invention, cause the further data processing device to carry out a method according to the invention for unlocking a communication interface of an electronic device for a motor vehicle. The further instructions can be present, for example, as program code. The program code can be provided, for example, as binary code or assembler and / or as source code of a programming language, for example, C, and / or as a program script, for example, Python.

[0058] According to a further aspect of the invention, a computer-readable storage medium is provided which stores a computer program according to the invention or a further computer program according to the invention.

[0059] The computer program, the further computer program and the computer-readable storage medium can be referred to as respective computer program products comprising the instructions or the further instructions.

[0060] Further features of the invention emerge from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and / or shown in the figures can be encompassed by the invention not only in the respectively specified combination, but also in other combinations. In particular, the invention can also encompass embodiments and combinations of features that do not have all the features of an originally formulated claim. Furthermore, the invention can encompass embodiments and combinations of features that go beyond the combinations of features set out in the backreferences to the claims or deviate from them.

[0061] The invention is explained in more detail below using specific embodiments and associated schematic drawings. In the figures, identical or functionally equivalent elements may be provided with the same reference numerals. The description of identical or functionally equivalent elements may not necessarily be repeated for different figures.

[0062] The figures show schematically

[0063] Fig. 1 is a flowchart of an exemplary embodiment of a method according to the invention for blocking a communication interface of an electronic device for a motor vehicle;

[0064] Fig. 2 is a flowchart of a further exemplary embodiment of a method according to the invention for blocking a communication interface of an electronic device for a motor vehicle; and

[0065] Fig. 3 is a flowchart of a further exemplary embodiment of a method according to the invention for unlocking a communication interface of an electronic device for a motor vehicle.

[0066] Fig. 1 shows a schematic flow diagram of an exemplary embodiment of a method according to the invention for blocking a communication interface of an electronic device 1, for example a control unit or a sensor, for a motor vehicle.

[0067] The electronic device 1 was manufactured in a production line that includes a computing unit 2, for example, a programming station. For example, software installation and / or troubleshooting of the electronic device 1 was performed using the computing unit 2, and / or the electronic device was tested using the computing unit 2.

[0068] The electronic device 1 has a communication interface, in particular a debugging interface, for example a JTAG interface, which can be locked or unlocked by means of a cryptological key.

[0069] In step 100, a first identifier 3 is determined, in particular by means of the computing unit 2, which identifies a hardware component, for example an SSD memory or a motherboard, that identifies the computing unit 2, or a software component, for example an operating system or firmware, of the computing unit 2. The first identifier 3 can, for example, be a serial number of the hardware component or the software component. Optionally, at least one further first identifier can be determined, which identifies at least one further hardware component and / or at least one further software component of the computing unit 2. In step 120, the computing unit 2 receives a second identifier 4, which identifies the electronic device 1, for example a serial number of the electronic device 1.The computing unit 2 can determine the second identifier 4 automatically, for example, if it is stored electronically on the electronic device 1, or a user can provide the second identifier to the computing unit 2 via an input device, for example, a keyboard or an optical reader or an RFID reader. Optionally, the optical reader or RFID reader can also be positioned such that the second identifier 4 can be read automatically.

[0070] In step 140, the computing unit 2 generates a first input value for a predefined key derivation function based on the first identifier 3. If the at least one further first identifier has been determined, the computing unit 2 generates the first input value based on the first identifier 3 and on the at least one further first identifier. For example, the computing unit 2 can concatenate the first identifier 3 and the at least one further first identifier or combine them using a logical operation, for example XOR, to generate the first input value or convert it into the first input value using another operation. The computing unit 2 generates a second input value for the key derivation function based on the second identifier 4.

[0071] In step 160, the computing unit 2 applies the key derivation function to the first input value and the second input value, thus generating a key. In step 180, the communication interface is locked using the key, in particular automatically by the computing unit 2. In particular, the computing unit 2 is connected to the communication interface or another communication interface of the electronic device 1 for this purpose.

[0072] Fig. 2 shows a schematic flow diagram of a further exemplary embodiment of a method according to the invention for blocking the communication interface, which is based on the embodiment according to Fig. 1.

[0073] First, step 100 is also carried out here. At least one historical data record is stored on a storage device 5, in particular one provided externally to the computing unit 2. For the sake of simplicity, it is assumed below that the storage device stores several such historical data records; in the case of a single historical data record, the procedure is analogous. Each of the historical data records contains corresponding historical identification information for the hardware component or the software component of the computing unit 2 as well as a production period associated with the historical identification information. For different production periods, this can involve different hardware components or software components, which, however, always have the same function in the computing unit 2.Therefore, we still speak of "the" hardware component or "the" software component.

[0074] In particular, the production periods are unique, so that they can be clearly ordered chronologically. Accordingly, one of the production periods is clearly the most recent production period. The associated historical data record is referred to as the most recent historical data record, and its historical identification information is referred to as the most recent historical identification information 6. In step 200, the computing unit 2 reads the most recent historical identification information from the storage device s.

[0075] In step 220, the computing unit 2 determines a most recent historical first input value for the key derivation function based on the most recent historical identification information 6. For example, the historical identification information of the historical data records can be identical to the respective historical first input value. Alternatively, the historical identification information can each contain a historical first identifier and optionally at least one further historical first identifier, analogously to that described above with regard to the first identifier and the at least one further first identifier. The most recent historical first input value is then derived from the historical first identifier and optionally the at least one further historical first identifier of the most recent historical identification information 6, analogously to that described above with regard to the first input value.

[0076] In step 240, the computing unit 2 generates a hash value 8 depending on the first input value using a predetermined hash function, and in step 260, the computing unit 2 generates another hash value 7 depending on the most recent historical first input value using the hash function.

[0077] In step 260, computing unit 2 checks whether hash value 8 matches the additional hash value 7. If this is the case, steps 120 to 180 are executed as described above. Otherwise, in step 280, computing unit 2 stores another historical data record on storage device 5, which contains the first input value and a production period associated with the first input value, or which contains the first identifier and a production period associated with the first identifier. The additional historical data record is then the most recent historical data record.

[0078] This allows changes in the hardware or software component to be identified that would lead to a different initial input value. The communication interface can then be temporarily aborted and, for example, an error message or warning message can be issued. Steps 100 and 200 to 260 can then be repeated. Now, hash value 8 matches the additional hash value 7, so steps 120 to 180 can be executed as described above.

[0079] Fig. 3 shows a schematic flow diagram of an exemplary embodiment of a method according to the invention for unlocking a communication interface of an electronic device 1 that was locked by means of a method according to the invention as described with reference to Fig. 1 and Fig. 2.

[0080] In step 300, a further computing unit 9 different from the computing unit 2 receives a device identifier 10 of the electronic device 1, which corresponds to the second identifier. In step 320, the further computing unit 9 determines a manufacturing period of the electronic device 1 depending on the device identifier 10. In step 340, the further computing unit 9 selects the one of the historical data records that contains the manufacturing period of the electronic device 1. Depending on the historical identification information of the selected historical data record, the further computing unit 9 generates a historical first input value for the key derivation function and, depending on the device identifier 10, a current second input value for the key derivation function, analogously to that described above with regard to the first input value and the second input value.

[0081] In step 360, the further computing unit 9 reconstructs the key 11 using the key derivation function based on the historical first input value and the current second input value. In step 380, the communication interface is unlocked using the reconstructed key 11. As described, particularly with reference to the figures, the invention enables secure access protection for a communication interface of an electronic device for a motor vehicle. For this purpose, part-specific keys are generated, which, however, do not need to be stored but can be reconstructed as needed.

Claims

Patent claims 1. A method for blocking a communication interface of an electronic device (1) for a motor vehicle, wherein a first identifier (3) is determined which identifies a hardware component of a computing unit (2) of a production line in which the electronic device (1) was manufactured, or identifies a software component of the computing unit (2); a second identifier (4) is obtained which identifies the electronic device (1); a first input value for a predetermined key derivation function is generated by means of the computing unit (2) depending on the first identifier (3), and a second input value for the key derivation function is generated depending on the second identifier (4); a key is generated by means of the computing unit (2) using the key derivation function depending on the first input value and the second input value; and the communication interface is blocked using the key.

2. Method according to claim 1, wherein the electronic device (1) is programmed and / or tested at least in part by means of the computing unit (2) before the first identifier (3) is determined and / or a software installation of the electronic device is carried out by means of the computing unit (2) and / or a fault finding for the electronic device (1) is carried out by means of the computing unit (2).

3. Method according to one of the preceding claims, wherein the communication interface is a troubleshooting interface of the electronic device (1).

4. Method according to one of the preceding claims, wherein the second identifier (4) is determined depending on a serial number of the electronic device (1).

5. Method according to one of the preceding claims, wherein the first identifier is determined depending on a serial number of the hardware component of the computing unit (2) and / or depending on the serial number of the software component of the computing unit (2).

6. Method according to one of the preceding claims, wherein the software component is an operating system of the computing unit (2) or a firmware of the computing unit (2) and / or wherein the hardware component is a mainboard of the computing unit (2) or a data memory of the computing unit (2).

7. The method according to one of the preceding claims, wherein a further first identifier is determined which identifies a further hardware component of the computing unit (2) or identifies a further software component of the computing unit (2); and the first input value is generated depending on the first identifier and the further first identifier.

8. Method according to one of the preceding claims, wherein the key is generated with a bit length of at least 32 bits or at least 64 bits.

9. Method according to one of the preceding claims, wherein the electronic device is a sensor for the motor vehicle or an electronic control device for the motor vehicle.

10. Method according to one of the preceding claims, wherein at least one historical data set is provided on a storage device (5), wherein each historical data set of the at least one historical data set contains corresponding historical identification information for the hardware component or the software component of the computing unit (2) and a manufacturing period associated with the historical identification information; most recent historical identification information (6) of a most recent historical data set of the at least one historical data set is read from the storage device (5), wherein a most recent manufacturing period is associated with the most recent historical identification information (6); a most recent historical first input value is determined depending on the most recent historical identification information; using a predetermined hash function, a hash value (8) is generated depending on the first input value; using the hash function, a further hash value (7) is generated depending on the most recent historical first input value (6);if the hash value (7) does not match the further hash value (8), a further historical data record is stored on the storage device (5), which contains the first input value and a production period associated with the first input value or which contains the first identifier and a production period associated with the first identifier; 11. The method of claim 10, wherein for each historical data set of the at least one historical data set, as respective historical identification information, a respective historical first input value for the key derivation function or a respective historical first identifier.

12. A method for unlocking a communication interface of an electronic device (1) for a motor vehicle, which was locked by means of a method according to one of claims 1 to 9, wherein at least one historical data set is provided on a storage device (5), wherein each historical data set of the at least one historical data set contains corresponding historical identification information and a manufacturing period associated with the historical identification information; a device identifier (10) identifying the electronic device (1) is determined; depending on the device identifier (10), a manufacturing period of the electronic device (1) is determined; depending on the manufacturing period of the electronic device (1), one of the historical data sets is selected; depending on the historical identification information of the selected historical data set, a historical first input value for the key derivation function is generated; depending on the device identifier (10), a current second input value for the key derivation function is generated; using the key derivation function, a key (1) is reconstructed depending on the historical first input value and the current second input value; and the communication interface is unlocked using the reconstructed key (11).

13. Data processing device comprising a computing unit (2) which is configured to carry out a method according to one of claims 1 to 11.

14. Data processing device comprising a further computing unit (9) which is configured to carry out a method according to claim 12.

15. A computer program product comprising instructions which, when executed by a data processing device, cause the data processing device to perform a method according to any one of claims 1 to 12.

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