CN111200498A

CN111200498A - Verification of data packets in a motor vehicle

Info

Publication number: CN111200498A
Application number: CN201911133725.7A
Authority: CN
Inventors: C.布罗克豪斯
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-11-20
Filing date: 2019-11-19
Publication date: 2020-05-26
Also published as: DE102018219868A1

Abstract

Verification of data packets in a motor vehicle. The invention relates to a method (100) for verifying the authenticity of data packets which are exchanged by members of a communication network (30) of a motor vehicle, in particular control devices (5, 10, 15, 20, 25), via the communication network (30), wherein in particular a verification controller (50) is provided which is designed and set up to detect a communication via the communication network (30), comprising the following steps: -determining (120) an identifier, data, signature from a data package transmitted via the communication network (30), -verifying (130) the authenticity of the data package by checking the signature by means of a public key, -providing (140) a result of the verification, and-sending (150) the result as a reaction to a challenge of a member of the communication network (30).

Description

Verification of data packets in a motor vehicle

Technical Field

The invention comprises a method for verifying the authenticity of a data packet transmitted by a member of a communication network of a motor vehicle and a verification controller.

Background

In the automotive field, electronic control devices are increasingly being used today. These control devices form a control device complex. These control devices exchange information, data or signals via a communication bus, for example a CAN bus. A plurality of control devices communicate with each other. Some control units send data packets that are important for a plurality of other control units, for example, the state of charge is important for the inverter and for the engine controller. In order to check for possible undesired manipulation of the communication, for example possible undesired tampering with the communication by manipulated information or control instructions, it is known to encrypt the communication. However, encryption results in an increase in the required bandwidth.

Disclosure of Invention

The method according to the invention for verifying the authenticity of data packets exchanged, in particular transmitted, preferably transmitted, by a member of a communication network of a motor vehicle via the communication network comprises at least the method steps listed below, wherein the data packets comprise an identifier, data and a signature, and wherein preferably the signature is generated by a sender on the basis of the data to be transmitted and the identifier by means of a private key.

According to the invention: in one method step, the determination of the identifier, the data, the signature is performed from a data packet transmitted via the communication network.

According to the invention: in one method step, the authenticity of the data packet is verified by means of a signature using a public key. The signature is formed by the sender by means of a private key from the data to be transmitted and the identifier.

It is also proposed: providing the result of the verification.

According to the invention, it is also proposed: in one method step, the result is transmitted in response to a request, in particular a test request of a member of the communication network.

In the context of the method according to the invention, it is advantageous: in particular, forgery or manipulation can be detected and/or only a slight additional load of the communication, in particular the bandwidth, is required and/or the method can be applied to all topologies. The method can also be used, in particular retrofitted, in already existing control device complexes. Furthermore, no or only a minimally higher requirement is placed on the processor performance of the control device.

Advantageous embodiments and improvements of the method described in the independent claims result from the measures cited in the dependent claims.

It is advantageous that: the data package consists of data, an identifier and a signature, wherein the signature is created from the identifier and the data by means of a private key. The data packets are organized by the transmitting control device and transmitted by means of a communication network. The signature is created by the transmitting control device.

One possible embodiment is characterized in that: the authenticity of the data package is verified through the additional use of data and/or identifiers. An even more accurate statement may also be made in terms of authenticity.

One possible embodiment is characterized by the following method steps: the result of the verification, in particular the check, is provided by storing the result in a data memory, in particular a ring memory (ringspeecher). Thus, these results can also be accessed at a later point in time.

It is also conceivable: the result of the verification is provided and transmitted encrypted and/or signed. The signature is performed by means of a private key. These results cannot be manipulated by themselves.

One possible embodiment is characterized in that: a pseudo-unique identifier is generated and present for each packet. An identification of the respective data is given.

The invention also relates to an authentication controller for a communication network of a motor vehicle. The authentication controller has a communication interface that can be connected to a communication network of the motor vehicle. The communication interface is constructed and arranged to: data packets exchanged, in particular transmitted, via a communication network are read out, in particular together. It is advantageous that: the authentication controller is designed and set up to carry out the method according to the invention.

The communication network is in particular designed as a communication bus, in particular as a CAN, LIN, MOST, FLEXRAY or IP-based network.

One possible embodiment is characterized in that: providing a processing device constructed and arranged to: the identifier and the data are determined from the signature contained in the data packet in dependence on the public key. The processing apparatus is further constructed and arranged to: the data package is verified with respect to authenticity and the result of the verification is provided to a member of the communication network. Preferably, the processing device is designed as a computing unit, in particular as a microcontroller or microprocessor.

One possible embodiment is: the communication interface is constructed and arranged to: the results are transmitted, in particular, the inquiry of the member of the device complex, in particular a control device, to be controlled and are preferably transmitted encrypted. The communication interface is also constructed and arranged to read and receive data packets sent via the communication network together.

Drawings

Subsequently, the invention is elucidated with reference to the drawings. In the drawings:

FIG. 1 illustrates a control device complex without an authentication controller in accordance with the present invention;

FIG. 2 illustrates a control device complex having an authentication controller in accordance with the present invention;

FIG. 3 illustrates a method in accordance with the present invention; and

fig. 4 to 7 show the flow of the method according to the invention by way of example of a simplified control device complex.

Detailed Description

The control device complex 1 is composed of a plurality of electronic control devices. Increasingly, each component has a control device, in particular an engine control device, an ABS, a window lifter, etc. The control device has a communication means, whereby the control device can communicate with other control devices, in particular by means of a communication network, preferably a communication bus.

The control device combination comprises which control devices are dependent on the type of equipment and/or drive of the motor vehicle, in particular internal combustion engines, fuel cell engines, hybrid engines, plug-in hybrid engines, electric motors.

Fig. 1 shows a part of a control unit combination 1 of an electrically driven motor vehicle by way of example. By way of example, the

control devices

5, 10, 15, 20, 25 of the control device complex 1 are shown, which are responsible for the actuation. The illustrated control device shows only an exemplary part of a control device combination 1 of a motor vehicle, in particular a motor vehicle. The illustrated control device complex 1 comprises:

an engine control device 5 for controlling a drive, in particular an electric drive and/or an internal combustion engine of a motor vehicle.

An inverter 10 or converter having the following tasks: the multiphase alternating voltage, in particular the three-phase alternating voltage, of the generator is converted into a direct voltage for charging the electrical energy store. In the reverse case, the direct voltage of the electrical energy accumulator is converted into a multiphase alternating voltage when the electric motor is driven. The inverter has other tasks, such as conversion of voltage or current. Preferably, the drive motor simultaneously also acts as a generator, and vice versa. Correspondingly, the inverter must also convert the electrical energy generated, for example, during deceleration, so that it can be fed into the electrical energy store. The electrical energy store is an electrochemical-based rechargeable storage device for electrical energy. The electrical energy accumulator comprises at least one battery cell. Preferably, the battery cell is a rechargeable memory element, in particular a storage battery, preferably a secondary element or a secondary battery.

The BDU 15, i.e. the battery disconnect unit, regulates electrical switches, such as relays or transistors, which interrupt and/or switch on the current supply and current consumption of the electrical energy store.

The BCU20, i.e. the battery control unit, undertakes the calculation of the parameters of the energy store, such as the state of charge, the state of the energy store, etc.

The CSC25, i.e. the cell super circuit, takes over the detection of the energy store data, such as the cell voltage, the current and/or the temperature of the individual cells or of the entire energy store.

The plug-in hybrid control device complex 1 includes, for example, the following control devices: a motor control device, a transmission control device, an exhaust gas aftertreatment control device, a battery pack management control device, an internal combustion engine control device, and the like.

The

individual control devices

5, 10, 15, 20, 25 are connected to one another via a communication network 30. The communication network 30 is in particular a wireless network or a wired network. In particular to a communication bus, preferably to a MOST bus, a CAN bus, a LIN bus, a FlexRay bus. The communication network 30 may also be IP based. The

individual control devices

5, 10, 15, 20, 25 exchange data packets by means of a communication network 30. These data packets comprise, inter alia, data, such as measurement data and/or control instructions, power requirements, energy calls, status information, etc.

An example of the communication of the control device combination 1 according to fig. 1 shown in fig. 1 may be. The CSC25 periodically detects data of the accumulator, such as voltage, current and temperature, and communicates these data via the communication network 20. BCU20 periodically calculates the state of charge, state of health and possible callable power of the battery pack. The BCU20 sends this information to the BDU 15 and the engine control device 5. At the beginning of the driving cycle, BDU 15 has already performed the precharging and closed the electrical switches, in particular the relays. The torque request for the drive motor is sent via the communication network 30, for example because the vehicle should be moving from a stationary state. In this regard, the BCU reports the power that can be invoked. The inverter 10 calculates what torque can be applied to the drive motor. The engine control device 5 actuates the drive motor with a corresponding power. In this case, the engine control apparatus 5 accesses data of the BCU20, CSC 25.

The entire communication takes place via the communication network 30. It becomes apparent in this example that: the

control devices

5, 10, 15, 20, 25 communicate with each other and exchange data packets. In the case of known control device complexes, the

control devices

5, 10, 15, 20, 25 communicate with one another without checking whether the addressed data packet is sent by an authorized control device. The checking in the individual control devices increases the requirements for the computing performance of the control devices in particular.

In fig. 2, the same control device complex 1 as in fig. 1 is shown. The control device complex 1 is extended with members that can implement the method, in particular an authentication controller 50 according to the invention.

The verification controller 50 enables checking of data packets sent via the communication network 30 with respect to accuracy and authenticity. The validation controller enables, for example, the recognition of an impermissible commissioning in which a manipulated data packet, for example, indicating that the energy store is high in power, is sent, so that the engine control unit draws more power from the energy store. Impermissible debugging may be performed by changing the software of the control device, by manipulating data packets, or sending data packets with manipulated content.

Impermissible debugging can result in: more energy is called up from the electrical energy store than the electrical energy store can provide without damage. Sensor data packets can also be falsified in order, for example, to reach a higher charge state of the battery pack. Such measures of adjustment are mostly achieved at the expense of the service life of the electrical energy accumulator or other components of the motor vehicle.

The authentication controller 50 is designed and set up to carry out the method 100 according to the invention.

A flow chart of the method 100 according to the invention is shown in fig. 3. Method 100 includes a number of method steps, the order of which may be interchanged.

In a method step 110, the communication via the communication network 30 is monitored. The monitoring of the communication includes, in particular, the reading together of data packets transmitted via the communication network 30. The data packet transmitted via the communication network 30 is received by the authentication controller 50. In particular in bus systems, the data packets are also transmitted to members of the bus system which do not need the individual data packets of the data packets at all. The member identifies whether the data packet is specific to said member, in particular in terms of the sender and/or recipient of the data packet and/or an identifier and/or data.

In a method step 120, a signature and/or data and/or identifier and/or sender is determined from the received data packet.

The signature is preferably created by the sender by means of a private key from the identifier and the data. Preferably, asymmetric cryptographic systems are involved. The signature is a value calculated by means of a private key, in particular a secret key. The private key is fixedly assigned to the sender, i.e. the control device. The private key is assigned to each control device from the factory. Learning is performed by a diagnostic service that is protected in the factory. Each individual control device obtains its own private key. Advantageously, only the control device, in which the data packet has to be checked with regard to authenticity, has to be extended with this functionality. This is, for example, a safety-relevant control device and/or a control device that is important for the drive.

In a method step 130, the authenticity of the data packet is determined by means of the signature and the public key.

Preferably, the verification is performed by means of the data and/or the identifier and the signature and the public key. The determination corresponds to the authentication of the signature by means of a public key.

In a method step 140, the result of the verification 130 is provided. The provision can be effected in particular by means of transmission via the communication network 30 and/or as storage in a data memory. The result of the verification 130 is stored in a data memory, in particular a ring memory, together with the identifier of the data packet.

In an optional method step 145, the interrogation of the control device is checked with respect to the authenticity of the data packet.

In a method step 150, the result is transmitted as a reaction to the detected, in particular received, query, which the member of the communication network 30, in particular the control device, has transmitted. The query comprises, inter alia, an identifier of the data packet. Preferably, the verification controller 50 extracts the result of the verification from the data storage. To determine the correct result, the data store is searched for the identifier and the associated result is read out. The data memory is in particular a database or a table.

Preferably, the result of the verification is sent encrypted to the querying control device.

The control device may send a challenge to the verification controller 50 and obtain information about the authenticity of the data packet. The challenge includes an identifier of the data package whose authenticity and/or accuracy is queried.

In fig. 4, a fragment of the control device complex 1 is shown. The fragment includes the authentication controller 50, BCU20 and CSC 25. The method 100 according to the invention should be explained in terms of the following example and fig. 4 to 7.

The CSC25 detects measurement data of the electrical energy accumulator, such as voltage, current and temperature. For example, the CSC25 detects that the accumulator provides a voltage of 400V and a current of 50A. The CSC25 also detects, for example, that the accumulator has a temperature of 30 ℃. To transmit data, the control device, here the CSC25, generates a pseudo-unique identifier. The generated identifier is for example 488213.

The signature is determined from the data (here the measurement data), the identifier and the private key. The determined signature is, for example, 0XB1F4D 32. The measurement data, the signature and the identifier are combined in a data packet and transmitted, in particular transmitted, by means of a communication network. In particular, the data packet is sent to the BCU20 via a communication network, in particular a bus system.

In fig. 5, the BCU20, as well as other control devices, receives data packets that have been sent onto the communication network. The BCU20 receives a data packet with data, an identifier and a signature. If the data is important to the BCU, the BCU processes the data.

The control device can extract these data and directly process them further. Alternatively and/or additionally, the control device may allow checking authenticity by verifying the controller 50 and/or the method 100.

The authentication controller 50 receives the data packet. The verification controller 50 has also received the data packet by detecting, in particular reading together, the communication of the communication network. To this end, the authentication controller monitors the communication network 30 in accordance with method step 110.

In a method step 120, a signature, data, identifier and/or sender is determined from the received data packet.

In a method step 130, the authenticity of the data packet is verified by means of the public key. The data package is verified in dependence on, inter alia, the data and/or the identifier, the signature and the public key. It may be determined, in particular by the verification controller 50, that: whether the data is authentic or whether the data packet is transmitted by an authorized control device. The verification controller 50 receives the same data and checks the validity of the measurement data and the identifier by means of the public key of the CSC 25.

In a method step 140, the result of the check is provided, in particular stored, together with the identifier. In particular, the results are stored in a data memory, preferably in a circular buffer, together with the identifier.

Often, but not necessarily, in every packet, the control device, here illustratively the BCU20, requests the result of the authentication with a description of the identifier when authenticating the control 50. Fig. 6 exemplarily shows such a query.

According to method step 150 and fig. 7, the verification control 50 sends the result back to the control device that has requested the check. The communication is preferably carried out exclusively between the BCU20 and the authentication control 50, in particular encrypted and/or signed. The necessary keys are programmed in the factory. In the case of a less negative check, the BCU20 may take corresponding measures.

The method 100 can also be carried out by an already existing control device of the control device complex 1. The control devices required for this purpose only have to be designed and set up to carry out the method 100. Preferably, the control device requires a processing unit, in particular a microcontroller or microprocessor, which is designed and set up to carry out the method 100 according to the invention.

According to one embodiment of the invention, only certain data packets need to be protected by the method 100. In particular, not all packets must be validated by the method 100. The data packets to be protected are specified during the system design, for example safety-relevant data, drive-relevant data or data which can lead to damage in the case of manipulation. Preferably, the information for authentication may be transmitted in addition to the data packet that is normally transmitted.

According to one embodiment, only certain data packets need to be examined, in particular verified 130. The checking for authenticity is optional. Thereby, the calculation performance in the verification controller 50 can be reduced.

For the purpose of reduction, the frequency of the check can be reduced and the verification, i.e. the method steps starting from 120, can be performed, for example, every second or every 10 seconds. The selected delay is not allowed to cause a security risk.

Preferably, temporal, message-related or control device-related restrictions can be made. Therefore, the number of verifications can be reduced.

The proposed method 100 expands the possibility of communication with simultaneous verification of important data packets, while enabling a flexible control device architecture.

Claims

1. Method (100) for verifying the authenticity of data packets which are exchanged via a communication network (30) of a motor vehicle by members of the communication network (30), in particular control devices (5, 10, 15, 20, 25), wherein in particular a verification controller (50) is provided which is designed and set up to detect a communication via the communication network (30), having the following steps:

-determining (120) an identifier, data, signature from data packets transmitted via the communication network (30),

verifying (130) the authenticity of the data package by checking the signature by means of a public key,

providing (140) the result of said verification, and

-sending (150) the result as a reaction to a query of a member of the communication network (30).

2. The method (100) according to the preceding claim, wherein the data package consists of data, an identifier and a signature, wherein the signature is created from the identifier and the data by means of a private key.

3. The method (100) according to one of the preceding claims, wherein the providing (140) comprises storing (140) the result of the verification in a data memory, in particular a ring memory.

4. The method (100) according to one of the preceding claims, wherein the result is provided and sent encrypted and/or signed.

5. The method (100) according to one of the preceding claims, having the steps of:

generate a pseudo-unique identifier for each packet.

6. Authentication controller (50) for a communication network (30) of a motor vehicle, having a communication interface which can be connected to the communication network (30) of the motor vehicle and which is designed and set up to read out data packets transmitted via the communication network (30), characterized in that the authentication controller (50) is designed and set up to carry out the method (100) according to one of the preceding claims.

7. Authentication controller (50) according to the preceding claim, characterized in that processing means are provided which are constructed and set up to authenticate the authenticity of a data packet by means of a public key and to provide the result of said authentication to a member of the communication network (30).

8. Authentication controller (50) according to one of claims 6 to 7, characterized in that the communication interface is constructed and set up to send the result, in particular in response to a member's inquiry and preferably encrypted.