JP6698190B2 - Fraud handling method, fraud detection electronic control unit, and network communication system - Google Patents

Description

  The present disclosure relates to a technique of detecting and coping with an illegal frame transmitted in an in-vehicle network or the like in which an electronic control unit communicates.

  2. Description of the Related Art In recent years, a large number of devices called electronic control units (ECUs) are arranged in systems in automobiles. A network connecting these ECUs is called an in-vehicle network. There are many standards for in-vehicle networks. Among them, one of the most mainstream in-vehicle networks is a standard called CAN (Controller Area Network) defined by ISO11898-1 (see "Non-Patent Document 1").

  In CAN, the communication path is composed of two buses, and the ECU connected to the buses is called a node. Each node connected to the bus sends and receives a message called a frame. A transmission node that transmits a frame transmits a value of "1" called recessive and a value of "0" called dominant by applying a voltage to the two buses to generate a potential difference between the buses. When a plurality of transmitting nodes transmit recessive and dominant at exactly the same timing, the dominant is preferentially transmitted. The receiving node transmits a frame called an error frame when the format of the received frame is abnormal. The error frame is a frame in which the transmitting node or another receiving node is notified of an abnormality in the frame by continuously transmitting dominant for 6 bits.

  Also, in CAN, there is no identifier that indicates a destination or a source, the transmitting node attaches an ID called a message ID for each frame (that is, sends a signal to the bus), and each receiving node is predetermined. Receive only the message ID (ie read the signal from the bus). In addition, a CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) method is adopted, and arbitration is performed by a message ID during simultaneous transmission of a plurality of nodes, and a frame having a small message ID value is preferentially transmitted.

CAN Specification 2.0 Part A, [online], CAN in Automation (CiA), [November 14, 2014 search], Internet (URL: http://www.can-cia.org/fileadmin/cia/) specifications/CAN20A.pdf) RFC2104 HMAC: Keyed-Hashing for Message Authentication

  By the way, in an in-vehicle network, an illegal node is connected to a bus, and an illegal node illegally transmits a frame, so that the vehicle body may be illegally controlled.

  Therefore, the present disclosure discloses a fraud detection electronic control unit (fraud detection) that prevents the ECU from performing a process based on a fraudulent frame transmitted to a bus in a network communication system that communicates according to the CAN protocol, such as an in-vehicle network. ECU) is provided. The present disclosure also provides a fraud handling method for preventing execution of processing corresponding to a fraudulent frame, and a network communication system including a fraud detection ECU.

In order to solve the above problems, a fraud handling method according to an aspect of the present disclosure is a fraud handling method used in a network communication system including a plurality of electronic control units that communicate via a bus according to a CAN (Controller Area Network) protocol. Then, a first determination step of determining whether or not the content of the predetermined field in the frame in which the transmission is started satisfies a predetermined condition indicating fraud, and a predetermined field of the frame in the first determination step. When it is determined that the content satisfies the predetermined condition, a transmission step of transmitting an error frame before the end of the frame is transmitted, the number of times the error frame is transmitted in the transmission step, the error frame A recording step of recording for each ID represented by the content of the ID field included in the frame to be transmitted, and when the number of times for each ID recorded by the recording step exceeds a predetermined number, A second determining step for determining that the ID is illegal, wherein the predetermined field is a field representing an ID, and the first determining step determines the ID represented by the content of the predetermined field in advance. By comparing with one or more IDs indicated by the ID list information to determine whether or not the predetermined condition is satisfied. In the determining step, the ID represented by the content of the predetermined field is compared with the ID. All the IDs of one or more indicated by the list information are compared, and if they do not match, it is determined that the predetermined condition is satisfied.
In order to solve the above problems, a fraud handling method according to an aspect of the present disclosure is a fraud handling method used in a network communication system including a plurality of electronic control units that communicate via a bus according to a CAN (Controller Area Network) protocol. Then, a determination step of determining whether or not the content of the predetermined field in the frame in which the transmission is started meets a predetermined condition indicating fraud, and in the determination step, the content of the predetermined field of the frame satisfies the predetermined condition. When it is determined that the error frame is transmitted, the transmission step of transmitting the error frame before the end of the frame is transmitted, and the number of times the error frame is transmitted in the transmission step are the transmission targets of the error frame. A recording step of recording for each ID represented by the content of the ID field included in the frame, and an informing step of informing when the number of times of each ID recorded by the recording step exceeds a predetermined number. It is a fraud handling method including.

  In order to solve the above problems, a fraud detection electronic control unit according to an aspect of the present disclosure is a fraud detection electronic control unit that is connected to a bus used by a plurality of electronic control units that communicate according to a CAN protocol for communication. A receiving unit that receives a frame whose transmission has started, a determining unit that determines whether or not the content of a predetermined field in the frame received by the receiving unit satisfies a predetermined condition indicating fraud, and the determining unit. In the case where it is determined that the content of the predetermined field of the frame satisfies the predetermined condition in, the transmitting unit that transmits the error frame before the end of the frame is transmitted, and the error frame is transmitted by the transmitting unit. A recording unit that records the number of times for each ID represented by the content of the ID field included in the frame that is the target of transmitting the error frame, and the number of times for each ID recorded by the recording unit is a predetermined number of times. The fraud detection electronic control unit is provided with a notifying unit that gives a notification when the value exceeds.

  In order to solve the above problems, a network communication system according to an aspect of the present disclosure includes a plurality of electronic control units that communicate via a bus according to the CAN protocol and a fraud detection electronic control unit connected to the bus. In the network communication system, the fraud detection electronic control unit has a receiving unit that receives a frame whose transmission is started and a content of a predetermined field in the frame received by the receiving unit satisfy a predetermined condition indicating fraud. A determination unit that determines whether or not to perform the error frame transmission, and if the determination unit determines that the content of the predetermined field of the frame satisfies the predetermined condition, the error frame is transmitted before the end of the frame is transmitted. And a recording unit that records the number of times an error frame is transmitted by the transmitting unit, for each ID represented by the content of the ID field included in the frame that is the target of transmitting the error frame, The network communication system uses a plurality of buses for communication between the plurality of electronic control units, the notification unit performing a notification when the number of times for each ID recorded by the recording unit exceeds a predetermined number. A gateway device having a function of transferring a frame between the plurality of buses and a plurality of the fraud detection electronic control units connected to different buses, the predetermined field being a field representing an ID, The determination unit compares the ID represented by the content of the predetermined field with one or more IDs indicated by predetermined ID list information to determine whether or not the predetermined condition is satisfied. The ID list information is a different network communication system for each of the plurality of fraud detection electronic control units.

  According to the present disclosure, in a network communication system that communicates according to the CAN protocol, even if an illegal node is connected to a bus and an illegal frame is transmitted, it is possible to prevent the ECU from executing a process based on the illegal frame. ..

It is a figure which shows the whole structure of the vehicle-mounted network system which concerns on Embodiment 1. It is a figure which shows the format of the data frame prescribed|regulated by the CAN protocol. It is a figure which shows the format of the error frame prescribed|regulated by the CAN protocol. It is a block diagram of a head unit. It is the figure which showed an example of the reception ID list. It is a block diagram of a gateway. It is a figure showing an example of a transfer rule. 3 is a configuration diagram of an ECU according to the first embodiment. FIG. It is the figure which showed an example of the reception ID list. It is a figure which shows an example of ID and the data field in the frame transmitted from ECU connected to the engine. It is a figure which shows an example of ID and the data field in the frame transmitted from ECU connected to the brake. It is a figure which shows an example of the ID and the data field in the frame transmitted from ECU connected to the door opening/closing sensor. It is a figure which shows an example of the ID and the data field in the frame transmitted from ECU connected to the window opening/closing sensor. FIG. 3 is a configuration diagram of a fraud detection ECU according to the first embodiment. It is a figure showing an example of a regular ID list held by a fraud detection ECU. It is a figure showing an example of a regular ID list held by a fraud detection ECU. It is a figure which shows an example of the state of the fraud detection counter for every message ID. FIG. 7 is a sequence diagram showing an operation example relating to detection and execution prevention of an illegal frame in the first embodiment. It is a figure which shows the whole structure of the vehicle-mounted network system which concerns on Embodiment 2. FIG. 4 is a configuration diagram of a fraud detection ECU according to a second embodiment. FIG. 6 is a diagram showing an example of a data range list held in a fraud detection ECU. FIG. 24 is a sequence diagram showing an operation example related to detection of an illegal frame and execution prevention in the second embodiment (continued from FIG. 23). FIG. 23 is a sequence diagram showing an operation example related to detection and execution prevention of an illegal frame in the second embodiment (continued from FIG. 22). It is a figure which shows the whole structure of the vehicle-mounted network system which concerns on Embodiment 3. 7 is a configuration diagram of an ECU according to a third embodiment. FIG. It is a figure which shows an example of ID and the data field in the data frame transmitted from ECU connected to the engine. It is a figure which shows an example of ID and the data field in the data frame transmitted from ECU connected to a brake. It is a figure which shows an example of ID and the data field in the data frame transmitted from ECU connected to the door opening/closing sensor. It is a figure which shows an example of ID and the data field in the data frame transmitted from ECU connected to the window opening/closing sensor. FIG. 7 is a configuration diagram of a fraud detection ECU according to a third embodiment. FIG. 16 is a diagram showing an example of counter values for each message ID held in the counter holding unit according to the third embodiment. FIG. 34 is a sequence diagram showing an operation example relating to detection and execution prevention of an unauthorized frame in the third embodiment (continued from FIG. 33). FIG. 33 is a sequence diagram showing an operation example relating to detection and execution prevention of an unauthorized frame in the third embodiment (continued from FIG. 32).

  A fraud handling method according to an aspect of the present disclosure is a fraud handling method used in a network communication system including a plurality of electronic control units that communicate via a bus according to a CAN (Controller Area Network) protocol, in which transmission is started. A determination step of determining whether the content of the predetermined field in the frame corresponds to a predetermined condition indicating fraud, and the determination step determines that the content of the predetermined field of the frame corresponds to the predetermined condition. And a transmitting step of transmitting an error frame before the end of the frame is transmitted. As an example of the predetermined condition indicating fraud, for example, the content of the predetermined field is not included in the list indicating the legal value group, is included in the list indicating the illegal value group, is within a certain range or is constant. It is possible to cite that the value is a characteristic value (for example, an even number), the result of performing a predetermined operation on the content value becomes a predetermined value, and the like. As a result, in a network communication system that communicates according to the CAN protocol, even if an unauthorized node is connected to the bus and an unauthorized frame is transmitted, processing based on the unauthorized frame is prevented from being executed by each node (ECU). it can.

  Further, in the transmitting step, the transmission of the error frame may be performed before the end of the CRC sequence in the frame is transmitted. As a result, for example, the ECU that confirms the CRC sequence and processes the frame cannot execute the process based on the invalid frame.

  Further, the predetermined field is a field representing an ID, and in the determining step, the ID represented by the content of the predetermined field is compared with one or more IDs indicated by predetermined ID list information, The determination as to whether or not the predetermined condition is satisfied may be performed. As a result, for example, it becomes possible to determine whether or not the ID field in the data frame or the remote frame is illegal, and it is possible to prevent the ECU from executing the process for the illegal frame.

  Further, the predetermined field is a control field, and in the determining step, the content is determined by determining whether or not the data length represented by the content of the predetermined field is included in a predetermined range. The determination as to whether or not the predetermined condition is satisfied may be performed. As a result, for example, it becomes possible to determine the illegality in the control field of the data frame or the remote frame, and it is possible to prevent the ECU from executing the process for the illegal frame.

  Further, in the determining step, the determination may be performed when the transmitted frame is a data frame, and the predetermined field may be a data field. As a result, it is possible to prevent each ECU from executing processing corresponding to the data in accordance with the data in the incorrect data frame.

  In the determining step, it is determined whether or not the content corresponds to the predetermined condition by determining whether or not a data value which is the content of the predetermined field is included in a predetermined range. Good to do. As a result, even if an invalid data frame including a data value in an invalid range is transmitted, for example, it is possible to prevent each ECU from executing a process corresponding to the data.

  In the determining step, the message authentication code in the content of the predetermined field is verified by a predetermined verification processing procedure, and if the verification fails, the content is determined to correspond to the predetermined condition. Is also good. As a result, it is possible to prevent each ECU from executing a process for an illegal frame when an illegal frame to which a legitimate message authentication code is not added is transmitted.

  Further, the data frame transmitted by the legitimate electronic control unit includes, in the data field, a message authentication code calculated according to a variable that changes each time the data frame is transmitted. When the message authentication code in the content of the predetermined field does not reflect the variable that changes each time a message is transmitted, the content may be determined to correspond to the predetermined condition. Thereby, for example, it is possible to make it difficult to illegally decrypt the message authentication code.

  Further, the data frame transmitted by the legitimate electronic control unit having the message authentication code key includes a message authentication code generated using the message authentication code key in a data field, and in the determining step, the message authentication code is generated. The verification of the message authentication code in the content of the predetermined field may be performed using a key corresponding to the code key. Accordingly, for example, a plurality of authorized ECUs can have a common configuration for generating the message authentication code excluding the message authentication code key.

  Further, the fraud handling method further includes a recording step of recording the number of times the error frame is transmitted in the transmitting step, and a notification step of giving a notification when the number of times recorded by the recording step exceeds a predetermined number. Good as a matter. This allows the user or the like to be notified when an unauthorized frame is repeatedly transmitted.

  A fraud detection electronic control unit (fraud detection ECU) according to an aspect of the present disclosure is a fraud detection electronic control unit connected to a bus used by a plurality of electronic control units that communicate according to a CAN (Controller Area Network) protocol. A receiving unit that receives a frame whose transmission is started, and a determination unit that determines whether or not the content of a predetermined field in the frame received by the receiving unit satisfies a predetermined condition indicating fraud, A fraud-sensing electronic control unit comprising: a transmission unit that transmits an error frame before the end of the frame is transmitted when the determination unit determines that the content of the predetermined field of the frame satisfies the predetermined condition. Is. As a result, even if an illegal node is connected to a bus connecting a plurality of ECUs that communicate according to the CAN protocol and an illegal frame is transmitted, it is possible to prevent each ECU from executing a process based on the illegal frame.

  A network communication system according to an aspect of the present disclosure is a network communication including a plurality of electronic control units that communicate via a bus in accordance with a CAN (Controller Area Network) protocol and a fraud detection electronic control unit connected to the bus. In the system, the fraud detection electronic control unit is configured to determine whether the content of a receiving unit that receives a frame whose transmission has started and a predetermined field in the frame received by the receiving unit satisfy a predetermined condition indicating fraud. A determination unit that determines whether or not the determination field determines whether the content of the predetermined field of the frame satisfies the predetermined condition, and transmits an error frame before the end of the frame is transmitted. And a network communication system. As a result, even if an illegal node is connected to the bus and an illegal frame is transmitted, it is possible to prevent the ECU from executing a process based on the illegal frame.

  Note that these general or specific aspects may be realized by a recording medium such as a system, a method, an integrated circuit, a computer program or a computer-readable CD-ROM, and the system, the method, the integrated circuit, the computer program. Alternatively, it may be realized by any combination of recording media.

  Hereinafter, the fraud detection ECU according to the embodiment will be described with reference to the drawings. Each of the embodiments shown here shows one specific example of the present disclosure. Therefore, the numerical values, the components, the arrangement and connection form of the components, the steps (processes), the order of the steps, and the like shown in the following embodiments are examples and do not limit the present disclosure. Among the constituents in the following embodiments, constituents not described in the independent claims are constituents that can be added arbitrarily. In addition, each drawing is a schematic view and is not necessarily strictly illustrated.

(Embodiment 1)
Hereinafter, as an embodiment of the present disclosure, a vehicle including a fraud detection ECU that realizes a fraud handling method for preventing a process based on a fraudulent frame from being executed in another node (ECU) by using a message ID The network system 10 will be described with reference to the drawings.

[1.1 Overall Configuration of In-Vehicle Network System 10]
FIG. 1 is a diagram showing an overall configuration of an in-vehicle network system 10 according to the first embodiment. The vehicle-mounted network system 10 is an example of a network communication system that communicates according to the CAN protocol, and is a network communication system in a vehicle equipped with various devices such as a control device and a sensor. The vehicle-mounted network system 10 includes buses 500a and 500b, fraud detection ECUs 100a and 100b, a head unit 200, a gateway 300, and nodes such as ECUs 400a to 400d connected to various devices, which are connected to the bus. Composed of. Although not shown in FIG. 1, the vehicle-mounted network system 10 may include a number of ECUs other than the ECUs 400a to 400d, but here, for convenience, the ECUs 400a to 400d will be focused and described. The ECU is a device including, for example, a processor (microprocessor), a digital circuit such as a memory, an analog circuit, a communication circuit, and the like. The memory is a ROM, a RAM, or the like, and can store a control program (computer program) executed by the processor. For example, when the processor operates according to a control program (computer program), the ECU realizes various functions. The computer program is configured by combining a plurality of instruction codes indicating instructions to the processor in order to achieve a predetermined function. Here, description will be made on the assumption that an unauthorized ECU that transmits an unauthorized frame may be connected to the buses 500a and 500b.

  The fraud detection ECUs 100a and 100b are ECUs that are connected to the buses 500a and 500b, respectively, and determine whether the frames transmitted by the ECUs 400a to 400d are fraudulent, and if they are fraudulent, transmit an error frame. is there.

  The ECUs 400a to 400d are connected to any of the buses, and are also connected to the engine 401, the brake 402, the door opening/closing sensor 403, and the window opening/closing sensor 404, respectively. Each of the ECUs 400a to 400d acquires the state of a connected device (engine 401 or the like) and periodically transmits a frame (a data frame described later) indicating the state or the like to a network (that is, a bus).

  The gateway 300 is connected to a bus 500a connected to the fraud detection ECU 100a, the ECU 400a and the ECU 400b, a bus 500b connected to the fraud detection ECU 100b, the ECU 400c and the ECU 400d, and a bus 500c connected to the head unit 200, and received from each bus. It has a function of transferring a frame to another bus. It is also possible to switch whether or not to transfer the received frame for each connected bus. The gateway 300 is also a kind of ECU.

  The head unit 200 has a function of receiving a frame, has a function of receiving a frame transmitted from the ECUs 400a to 400d, displaying various states on a display (not shown), and presenting the state to the user. The head unit 200 is also a kind of ECU.

  In this in-vehicle network system 10, each ECU exchanges frames according to the CAN protocol. Frames in the CAN protocol include data frames, remote frames, overload frames, and error frames. For convenience of description, the data frame and the error frame will be mainly described.

[1.2 Data frame format]
Hereinafter, a data frame which is one of the frames used in the network according to the CAN protocol will be described.

  FIG. 2 is a diagram showing a format of a data frame defined by the CAN protocol. The figure shows a data frame in the standard ID format defined by the CAN protocol. The data frame includes an SOF (Start Of Frame), an ID field, an RTR (Remote Transmission Request), an IDE (Identifier Extension), a reserved bit “r”, a DLC (Data Length Code), a data field, and a CRC (Cyclic Redundancy Check) sequence. , CRC delimiter “DEL”, ACK (Acknowledgement) slot, ACK delimiter “DEL”, and EOF (End Of Frame).

  The SOF is composed of a 1-bit dominant. The state in which the bus is idle is recessive, and the start of frame transmission is notified by changing to dominant by SOF.

  The ID field is a field that is composed of 11 bits and stores an ID (message ID) that is a value indicating the type of data. When a plurality of nodes start transmitting at the same time, communication is arbitrated in this ID field, so that a frame having a small ID has a high priority.

  The RTR is a value for identifying the data frame and the remote frame, and is composed of dominant 1 bit in the data frame.

  Both IDE and “r” are composed of dominant 1 bit.

  DLC is composed of 4 bits and is a value indicating the length of the data field. The IDE, “r”, and DLC are collectively referred to as a control field.

  The data field is a value indicating the content of data to be transmitted, which is composed of 64 bits at maximum. The length can be adjusted every 8 bits. The specifications of the data to be sent are not specified by the CAN protocol, but are specified by the vehicle-mounted network system 10. Therefore, the specifications depend on the vehicle type, manufacturer (manufacturer), and the like.

  The CRC sequence is composed of 15 bits. It is calculated from the transmission values of the SOF, ID field, control field and data field.

  The CRC delimiter is a delimiter that represents the end of a CRC sequence composed of 1-bit recessive. The CRC sequence and the CRC delimiter are collectively referred to as a CRC field.

  The ACK slot is composed of 1 bit. The transmitting node transmits by making the ACK slot recessive. If the reception node has successfully received the CRC sequence, it transmits the ACK slot as a dominant. Since the dominant is given priority over the recessive, if the ACK slot is the dominant after the transmission, the transmitting node can confirm that one of the receiving nodes has successfully received.

  The ACK delimiter is a delimiter that represents the end of ACK and is composed of 1-bit recessive.

  The EOF is composed of 7-bit recessive and indicates the end of the data frame.

[1.3 Error frame format]
FIG. 3 is a diagram showing an error frame format specified by the CAN protocol. The error frame includes an error flag (primary), an error flag (secondary), and an error delimiter.

  The error flag (primary) is used to notify the occurrence of an error to other nodes. The node that has detected the error continuously sends a 6-bit dominant to notify other nodes of the occurrence of the error. This transmission violates the bit stuffing rule in the CAN protocol (do not continuously transmit the same value for 6 bits or more) and causes the transmission of an error frame (secondary) from another node.

  The error flag (secondary) is composed of a continuous 6-bit dominant used to notify the occurrence of an error to other nodes. All nodes that receive the error flag (primary) and detect the violation of the bit stuffing rule will transmit the error flag (secondary).

  The error delimiter “DEL” is a continuous recess of 8 bits and indicates the end of the error frame.

[1.4 Configuration of Head Unit 200]
The head unit 200 is provided in, for example, an instrument panel of an automobile, and is a display device such as a liquid crystal display (LCD) that displays information to be visually recognized by a driver, an input unit that receives a driver's operation, and the like. It is a kind of ECU equipped with.

  FIG. 4 is a configuration diagram of the head unit 200. The head unit 200 includes a frame transmission/reception unit 270, a frame interpretation unit 260, a reception ID determination unit 240, a reception ID list holding unit 250, a frame processing unit 220, a display control unit 210, and a frame generation unit 230. It is configured to include. Each of these constituent elements is a functional constituent element, and each function thereof is realized by a communication circuit in the head unit 200, an LCD, a processor that executes a control program stored in a memory, a digital circuit, or the like.

  The frame transmitting/receiving unit 270 transmits/receives a frame according to the CAN protocol to/from the bus 500c. The frame is received from the bus 500c one bit at a time and transferred to the frame interpretation unit 260. Further, the contents of the frame notified by the frame generation unit 230 are transmitted to the bus 500c one bit at a time.

  The frame interpretation unit 260 receives the frame value from the frame transmission/reception unit 270 and interprets it so as to map it to each field in the frame format defined by the CAN protocol. The frame interpretation unit 260 transfers the value determined to be the ID field to the reception ID determination unit 240. The frame interpreting unit 260 transfers the value of the ID field and the data field appearing after the ID field to the frame processing unit 220 according to the determination result notified from the reception ID determining unit 240, or determines the determination result. After receiving the frame, it is determined whether to stop receiving the frame (that is, stop interpreting the frame). Further, when the frame interpretation unit 260 determines that the frame does not comply with the CAN protocol, for example, the CRC value does not match, the item fixed as dominant is recessive, or the like, it transmits an error frame. To the frame generator 230. Further, when the frame interpretation unit 260 receives an error frame, that is, when it interprets that the value in the received frame is an error frame, it discards the frame thereafter, that is, stops the interpretation of the frame. To do. For example, when an error frame is interpreted in the middle of a data frame, the interpretation of the data frame is stopped, and no special processing is performed according to the data frame.

  The reception ID judgment unit 240 receives the value of the ID field notified from the frame interpretation unit 260, and receives each field of the frame after the ID field according to the message ID list held by the reception ID list holding unit 250. Determine whether to do. The reception ID determination unit 240 notifies the frame interpretation unit 260 of this determination result.

  The reception ID list holding unit 250 holds a reception ID list that is a list of IDs (message IDs) received by the head unit 200. FIG. 5 is a diagram showing an example of the reception ID list. The head unit 200 receives a frame (message) whose message ID is “1” from the ECU 400a connected to the engine 401, receives a frame whose message ID is “2” from the ECU 400b connected to the brake 402, A frame having a message ID of "3" is received from the ECU 400c connected to the door opening/closing sensor 403, and a frame having a message ID of "4" is received from the ECU 400d connected to the window opening/closing sensor 404.

  The frame processing unit 220 forms an image to be displayed on the LCD based on the content of the received frame (for example, the content of the message ID and the content of the data field), and notifies the display control unit 210 of the image. The frame processing unit 220 holds the contents of the received data field and displays an image (for example, a vehicle speed display image, window open/closed state display image) to be displayed on the LCD in accordance with the operation of the driver received through the input means. (For example, an image for use) may be selected and notified.

  The display control unit 210 displays the content notified by the frame processing unit 220 on the LCD or the like.

  The frame generation unit 230 configures an error frame according to the notification from the frame interpretation unit 260 instructing the transmission of the error frame, and notifies the frame transmission/reception unit 270 to transmit the error frame.

[1.5 Reception ID List Example 1]
FIG. 5 described above is a diagram showing an example of the reception ID list held in each of the head unit 200, the gateway 300, the ECU 400c, and the ECU 400d. The reception ID list illustrated in the figure is obtained by selectively receiving a frame including a message ID whose ID (message ID) value is one of "1", "2", "3" and "4". Used for processing. For example, when the reception ID list of FIG. 5 is held in the reception ID list holding unit 250 of the head unit 200, for frames whose message ID is neither "1", "2", "3", or "4". Causes the frame interpretation unit 260 to stop interpreting frames after the ID field.

[1.6 Configuration of Gateway 300]
FIG. 6 is a configuration diagram of the gateway 300. The gateway 300 includes a frame transmission/reception unit 360, a frame interpretation unit 350, a reception ID determination unit 330, a reception ID list holding unit 340, a frame generation unit 320, a transfer processing unit 310, and a transfer rule holding unit 370. It is configured to include. Each of these components is a functional component, and each function thereof is realized by a communication circuit in the gateway 300, a processor that executes a control program stored in the memory, a digital circuit, or the like.

  The frame transmission/reception unit 360 transmits/receives a frame according to the CAN protocol to/from each of the buses 500a, 500b, 500c. Frames are received from the bus one bit at a time and transferred to the frame interpretation unit 350. In addition, the contents of the frame are transmitted to the buses 500a, 500b, and 500c one bit at a time, based on the bus information indicating the transfer destination bus and the frame notified from the frame generation unit 320.

  The frame interpretation unit 350 receives the frame value from the frame transmission/reception unit 360 and interprets it so as to map it to each field in the frame format defined by the CAN protocol. The value determined as the ID field is transferred to the reception ID determination unit 330. The frame interpretation unit 350 transfers the value of the ID field and the data field (data) appearing after the ID field to the transfer processing unit 310 according to the judgment result notified from the reception ID judgment unit 330, or After receiving the determination result, it is determined whether to stop receiving the frame (that is, stop interpreting the frame). Further, when the frame interpretation unit 350 determines that the frame does not conform to the CAN protocol, it notifies the frame generation unit 320 to transmit an error frame. When the frame interpretation unit 350 receives an error frame, that is, when it interprets that the value in the received frame is an error frame, it discards the frame thereafter, that is, stops interpretation of the frame. To do.

  The reception ID judging unit 330 receives the value of the ID field notified from the frame interpreting unit 350, and receives each field of the frame after the ID field according to the message ID list held by the reception ID list holding unit 340. Determine whether to do. The reception ID determination unit 330 notifies the frame interpretation unit 350 of this determination result.

  The reception ID list holding unit 340 holds a reception ID list (see FIG. 5) which is a list of IDs (message IDs) received by the gateway 300.

  The transfer processing unit 310 determines the bus to be transferred according to the message ID of the received frame according to the transfer rule held by the transfer rule holding unit 370, and is notified from the frame interpretation unit 350 and bus information indicating the bus to be transferred. The frame generation unit 320 is notified of the message ID and the data. Note that the gateway 300 does not transfer the error frame received from one bus to another bus.

  The transfer rule holding unit 370 holds a transfer rule that is information indicating a rule for transferring a frame for each bus. FIG. 7 is a diagram showing an example of the transfer rule.

  The frame generation unit 320 forms an error frame according to the notification instructing the transmission of the error frame notified from the frame interpretation unit 350, and notifies the frame transmission/reception unit 360 of the error frame to be transmitted. Further, the frame generation unit 320 forms a frame using the message ID and data notified by the transfer processing unit 310, and notifies the frame transmission/reception unit 360 of the frame and bus information.

[1.7 Transfer Rule Example]
FIG. 7 shows an example of the transfer rule held by the gateway 300 as described above. This transfer rule associates a transfer source bus, a transfer destination bus, and a transfer target ID (message ID). This indicates that the frame is transferred regardless of the message ID in FIG. Further, "-" in the figure indicates that there is no frame to be transferred. The example in the figure shows that the frame received from the bus 500a is set to be transferred to the buses 500b and 500c regardless of the message ID. Further, among the frames received from the bus 500b, all the frames are transferred to the bus 500c, but only the frame having the message ID "3" is set to be transferred to the bus 500a. Shows. It also indicates that the frame received from the bus 500c is set so as not to be transferred to the bus 500a or the bus 500b.

[1.8 Configuration of ECU 400a]
FIG. 8 is a configuration diagram of the ECU 400a. The ECU 400a includes a frame transmission/reception unit 460, a frame interpretation unit 450, a reception ID determination unit 430, a reception ID list holding unit 440, a frame processing unit 410, a frame generation unit 420, and a data acquisition unit 470. Composed. Each of these constituent elements is a functional constituent element, and each function thereof is realized by a communication circuit in the ECU 400a, a processor that executes a control program stored in the memory, a digital circuit, or the like.

  The frame transmitting/receiving unit 460 transmits/receives a frame according to the CAN protocol to/from the bus 500a. The frame is received from the bus 500a one bit at a time and transferred to the frame interpretation unit 450. Further, the contents of the frame notified from the frame generation unit 420 are transmitted to the bus 500a.

  The frame interpretation unit 450 receives the frame value from the frame transmission/reception unit 460 and interprets it so as to map it to each field in the frame format defined by the CAN protocol. The value determined as the ID field is transferred to the reception ID determination unit 430. The frame interpreting unit 450 transfers the value of the ID field and the data field appearing after the ID field to the frame processing unit 410 according to the determination result notified from the reception ID determining unit 430, or determines the determination result. After receiving the frame, it is determined whether to stop receiving the frame (that is, stop interpreting the frame). Further, when the frame interpretation unit 450 determines that the frame does not conform to the CAN protocol, it notifies the frame generation unit 420 to transmit the error frame. Further, when the frame interpretation unit 450 receives an error frame, that is, when the value in the received frame is interpreted as an error frame, the frame interpretation unit 450 discards the frame thereafter, that is, stops interpretation of the frame. To do.

  The reception ID judgment unit 430 receives the value of the ID field notified from the frame interpretation unit 450, and receives each field of the frame after the ID field according to the list of message IDs held by the reception ID list holding unit 440. Determine whether to do. The reception ID determination unit 430 notifies the frame interpretation unit 450 of this determination result.

  The reception ID list holding unit 440 holds a reception ID list that is a list of IDs (message IDs) received by the ECU 400a. FIG. 9 is a diagram showing an example of the reception ID list.

  The frame processing unit 410 performs processing relating to a function that differs for each ECU according to the received frame data. For example, the ECU 400a connected to the engine 401 has a function of sounding an alarm when the door is open when the speed exceeds 30 km/h. The ECU 400a has, for example, a speaker for emitting an alarm sound. Then, the frame processing unit 410 of the ECU 400a manages data (for example, information indicating the state of the door) received from another ECU, and sounds an alarm sound under a certain condition based on the hourly speed acquired from the engine 401, etc. I do.

  The data acquisition unit 470 acquires data indicating the states of devices, sensors, etc. connected to the ECU, and notifies the frame generation unit 420 of the data.

  The frame generation unit 420 forms an error frame according to the notification instructing the transmission of the error frame notified from the frame interpretation unit 450, and notifies the frame transmission/reception unit 460 to transmit the error frame. Further, the frame generation unit 420 adds a predetermined message ID to the value of the data notified by the data acquisition unit 470 to form a frame, and notifies the frame transmission/reception unit 460.

  The ECUs 400b to 400d also have basically the same configuration as the above-described ECU 400a. However, the reception ID list stored in the reception ID list storage unit 440 may have different contents for each ECU. The ECU 400b holds the reception ID list illustrated in FIG. 9, and the ECU 400c and the ECU 400d hold the reception ID list illustrated in FIG. Further, the processing content of the frame processing unit 410 differs for each ECU. For example, the processing content of the frame processing unit 410 in the ECU 400c includes processing related to the function of sounding an alarm when the door is opened in a situation where the brake is not applied. For example, the frame processing unit 410 in each of the ECU 400b and the ECU 400d does not perform a particular process. It should be noted that each ECU may have functions other than those illustrated here. The contents of the frame transmitted by each of the ECUs 400a to 400d will be described later with reference to FIGS. 10 to 13.

[1.9 Reception ID List Example 2]
FIG. 9 described above is a diagram showing an example of the reception ID list held in each of the ECU 400a and the ECU 400b. The reception ID list illustrated in the figure is for selectively receiving and processing a frame including a message ID whose ID (message ID) value is one of "1", "2", and "3". Used. For example, if the reception ID list holding unit 440 of the ECU 400a holds the reception ID list of FIG. 9, the frame interpretation unit 450 will be used for frames whose message IDs are neither "1", "2", or "3". Interpretation of the frame after the ID field is stopped.

[1.10 Transmission Frame Example of ECU 400a Related to Engine]
FIG. 10 is a diagram showing an example of an ID (message ID) and a data field (data) in a frame transmitted from the ECU 400a connected to the engine 401. The message ID of the frame transmitted by the ECU 400a is "1". The data represents a speed (km/hour) per hour, takes a value in the range of 0 (km/hour) at the minimum to 180 (km/hour) at the maximum, and the data length is 1 Byte. From the top row to the bottom row of FIG. 10, message IDs and data corresponding to the respective frames sequentially transmitted from the ECU 400a are illustrated, and the state of acceleration from 0 km/hour to 1 km/hour is shown.

[1.11 Transmission Frame Example of ECU 400b for Braking]
FIG. 11 is a diagram showing an example of an ID (message ID) and a data field (data) in a frame transmitted from the ECU 400b connected to the brake 402. The message ID of the frame transmitted by the ECU 400b is "2". The data represents the degree of braking applied by a ratio (%), and the data length is 1 Byte. This ratio is 0 (%) when the brake is not applied at all, and 100 (%) when the brake is applied to the maximum. From the top row to the bottom row of FIG. 11, message IDs and data corresponding to the respective frames sequentially transmitted from the ECU 400b are illustrated, showing that the brake is gradually weakened from 100%.

[1.12 Example of Transmission Frame of ECU 400c Related to Door Opening/Closing Sensor]
FIG. 12 is a diagram showing an example of an ID (message ID) and a data field (data) in a frame transmitted from the ECU 400c connected to the door opening/closing sensor 403. The message ID of the frame transmitted by the ECU 400c is “3”. The data represents the open/closed state of the door, and the data length is 1 Byte. The data value is "1" when the door is open and "0" when the door is closed. 12 illustrates the message IDs and data corresponding to the respective frames sequentially transmitted from the ECU 400c from the upper row to the lower row in FIG. 12, showing a state in which the door is gradually closed to the closed state. ing.

[1.13 Transmission Frame Example of ECU 400d Related to Window Opening/Closing Sensor]
FIG. 13 is a diagram showing an example of an ID (message ID) and a data field (data) in a frame transmitted from the ECU 400d connected to the window opening/closing sensor 404. The message ID of the frame transmitted by the ECU 400d is "4". The data represents the open/closed state of the window in percentage (%), and the data length is 1 Byte. This ratio is 0 (%) when the window is completely closed, and 100 (%) when the window is fully open. From the top row to the bottom row of FIG. 13, message IDs and data corresponding to the respective frames sequentially transmitted from the ECU 400d are illustrated, and the window is gradually opened from the closed state.

[1.14 Configuration of Fraud Detection ECU 100a]
FIG. 14 is a configuration diagram of the fraud detection ECU 100a. The fraud detection ECU 100a includes a frame transmission/reception unit 160, a frame interpretation unit 150, a fraud frame detection unit 130, a regular ID list holding unit 120, a fraud detection counter holding unit 110, and a frame generation unit 140. It Each of these components is a functional component, and each function thereof is realized by a communication circuit in the fraud detection ECU 100a, a processor that executes a control program stored in the memory, a digital circuit, or the like. Although the fraud detection ECU 100b basically has the same configuration, the content of the list information (authorized ID list) held by the legitimate ID list holding unit 120 is different between the fraud detection ECU 100a and the fraud detection ECU 100b.

  The frame transmitting/receiving unit 160 transmits/receives a frame according to the CAN protocol to/from the bus 500a. That is, the frame transmitting/receiving unit 160 functions as a receiving unit that receives a frame when transmission of a frame on the bus is started, and also functions as a transmitting unit that transmits an error frame or the like to the bus. That is, the frame transmitting/receiving unit 160 receives a frame from the bus 500 a by 1 bit and transfers it to the frame interpreting unit 150. Further, the contents of the frame notified by the frame generation unit 140 are transmitted to the bus 500a.

  The frame interpretation unit 150 receives a frame value from the frame transmission/reception unit 160 and interprets it so as to map it to each field in the frame format defined by the CAN protocol. The value determined as the ID field is transferred to the fraudulent frame detection unit 130. Further, when the frame interpretation unit 150 determines that the frame does not conform to the CAN protocol, it notifies the frame generation unit 140 to transmit an error frame. Further, when the frame interpretation unit 150 receives an error frame, that is, when the value in the received frame is interpreted as an error frame, the frame interpretation unit 150 discards the frame thereafter, that is, stops interpretation of the frame. To do.

  The fraudulent frame detection unit 130 receives the value of the ID field notified from the frame interpretation unit 150, and determines whether the value of the ID field satisfies a predetermined condition indicating fraud. That is, the fraudulent frame detection unit 130 functions as a so-called determination unit that determines whether or not the content of the predetermined field in the received frame satisfies a predetermined condition indicating fraud. The predetermined condition indicating this injustice is a condition that the value of the ID field is not included in the list of message IDs held by the regular ID list holding unit 120. That is, it is determined whether or not the value of the notified ID field (message ID) is incorrect according to the list of message IDs held by the regular ID list holding unit 120. When a message ID not included in this list (that is, a regular ID list described later) is received, the received message ID is notified to the fraud detection counter holding unit 110 in order to increment the number of fraud detections. When a message ID that is not on the regular ID list is received, the frame generation unit 140 is notified to transmit an error frame. Further, when the number of fraud detections reaches a certain number or more, a notification is given from the fraud detection counter holding unit 110, and an error display message (frame) indicating that there is a fraudulent ECU that issues a corresponding message ID is displayed. The frame generation unit 140 is notified to transmit. The message ID of the error display message is predetermined, and the head unit 200 receives the message (frame) of this message ID and displays an error. Although the description of the error display message is omitted for convenience, the message ID of the error display message is posted in the reception ID list held by the gateway 300 and the head unit 200 and the regular ID list described later. However, in FIGS. 15 and 16, the message ID for the error display message is omitted.

  The regular ID list holding unit 120 holds a regular ID list, which is a list that predefines message IDs included in a frame to be transmitted on the bus 500a in the vehicle-mounted network system 10 (see FIGS. 15 and 16). ..

  The fraud detection counter holding unit 110 holds a fraud detection counter for counting the number of detections for each message ID. When the fraud detection unit 130 notifies the fraud detection counter, the fraud detection counter is incremented ( To increase. When the fraud detection counter reaches a certain number (predetermined number) or more, it notifies the fraud frame detection unit 130 that the number has exceeded the certain number. An example of the fixed number (predetermined number) here is a value determined in accordance with the handling rule of the transmission error counter in the CAN protocol. In the CAN protocol, the transmission error counter increments by 8 each time the ECU blocks transmission due to an error frame. Then, as a result, if the transmission error counter in the transmitting node counts up to 128, the transmitting node is defined to transition to the passive state and not to perform frame transmission. Therefore, if 17 larger than 128/8 (=16) is set as this fixed number, it is illegal when it is estimated that there is a transmitting node (illegal ECU) that ignores the rules relating to the transmission error counter in the CAN protocol. An error display message is transmitted from the detection ECU 100a. If an unauthorized ECU that transmits an unauthorized frame complies with the transmission error counter rule in the CAN protocol, the unauthorized ECU transmission error counter causes the unauthorized ECU transmission error counter to be transmitted. It is incremented by 8. In this case, if the transmission error counter of the unauthorized ECU rises to 128 by repeating the transmission of the unauthorized frame, the unauthorized ECU transits to the passive state, and the unauthorized ECU stops transmitting the unauthorized frame. ..

  The frame generation unit 140 composes an error frame according to the notification instructing the transmission of the error frame notified from the frame interpretation unit 150, and notifies the frame transmission/reception unit 160 of the error frame for transmission. Further, the frame generation unit 140 composes an error frame according to the notification instructing the transmission of the error frame notified from the unauthorized frame detection unit 130, and notifies the frame transmission/reception unit 160 of the error frame for transmission. Further, the frame generation unit 140 notifies the frame transmission/reception unit 160 of the error display message and causes the frame transmission/reception unit 160 to transmit the error display message in accordance with the notification of the transmission of the error display message notified from the unauthorized frame detection unit 130.

[1.15 Example of Regular ID List of Fraud Detection ECU 100a]
FIG. 15 is a diagram showing an example of the regular ID list held in the regular ID list holding unit 120 of the fraud detection ECU 100a. The regular ID list illustrated in the figure shows that a frame including a message ID whose ID (message ID) value is any one of "1", "2", and "3" can flow to the bus 500a. ..

[1.16 Example of Regular ID List of Fraud Detection ECU 100b]
FIG. 16 is a diagram showing an example of the regular ID list held in the regular ID list holding unit 120 of the fraud detection ECU 100b. In the regular ID list illustrated in the figure, a frame including a message ID whose ID (message ID) value is any one of "1", "2", "3" and "4" can flow to the bus 500b. Is shown.

[1.17 Example of Fraud Detection Counter Saved List]
FIG. 17 is a diagram showing an example of the state of the fraud detection counter for each message ID. The example in the figure shows that only the fraud detection counter with the message ID “4” has detected fraud once, and has not detected any other message ID. That is, in this example, the fraud-sensing ECU 100a detects that the message (frame) with the message ID "4" that should not originally flow on the bus 500a is once transmitted, and the fraud-sensing counter corresponding to the corresponding message ID "4" is detected. Shows the case where is incremented by 1.

[1.18 Sequence Related to Detection of Illegal Frame]
Hereinafter, operations of the fraud detection ECU 100a, the ECU 400a, the ECU 400b, the gateway 300, etc. connected to the bus 500a when the fraudulent ECU is connected to the bus 500a of the vehicle-mounted network system 10 having the above-described configuration will be described.

  FIG. 18 is a sequence diagram showing an operation example in which the fraud-sensing ECU 100a detects a fraudulent frame (message) and prevents another ECU from performing a process corresponding to the fraudulent frame. The figure shows an example in which an unauthorized ECU transmits a data frame having a message ID of "4" and a data field (data) of "255 (0xFF)" to the bus 500a. Each sequence here means each processing procedure (step) in various devices.

  First, the unauthorized ECU starts transmission of a data frame having a message ID of "4" and data of "255 (0xFF)" (sequence S1001). The value of each bit forming the frame is sequentially transmitted to the bus 500a in the order of SOF and ID field (message ID) according to the above-mentioned data frame format.

  When the unauthorized ECU finishes sending up to the ID field (message ID) to the bus 500a, the fraud detection ECU 100a, the ECU 400a, the ECU 400b, and the gateway 300 each receive the message ID (sequence S1002).

  Each of the ECU 400a, the ECU 400b, and the gateway 300 checks the message ID using the held reception ID list (sequence S1003). At this time, the fraud detection ECU 100a checks the message ID using the held regular ID list (sequence S1004). That is, the fraud detection ECU 100a determines whether or not the content of the ID field in the transmitted frame corresponds to a predetermined condition indicating that the fraud (not listed in the regular ID list).

  In sequence S1003, the ECU 400a and the ECU 400b terminate the reception because the reception ID list held by each of them does not include "4" (see FIG. 9). That is, the unauthorized ECU does not interpret the frame for continuing the transmission and does not perform the process corresponding to the frame. Further, in the sequence S1003, the gateway 300 continues the reception because the held reception ID list includes “4” (see FIG. 5). Further, in sequence S1004, the fraud-sensing ECU 100a determines that the fraudulent message ID is an fraudulent message ID because the regular ID list held therein does not include "4", and subsequently starts preparation for issuing an error frame ( Sequence S1005).

  Following the sequence S1003, the gateway 300 continues to receive the frame. For example, while the fraud-sensing ECU 100a is preparing to issue an error frame, the fraudulent ECU sequentially sends the RTR and control fields (IDE, r, DLC), which are the portions after the ID field, onto the bus 500a. Then, the data field is sequentially transmitted bit by bit. The gateway 300 receives this RTR and control field (IDE, r, DLC), and then starts receiving the data field (sequence S1006).

  Next, preparation for issuing the error frame is completed, and the fraud-sensing ECU 100a transmits the error frame (sequence S1007). The transmission of the error frame is performed before the end of the invalid frame is transmitted (for example, before the end of the CRC sequence is transmitted). In this operation example, the operation is performed in the middle of the data field. When transmission of this error frame is started, the middle part of the data field of the frame being transmitted from the unauthorized ECU is overwritten by the error frame (priority dominant bit string) on the bus 500a.

  Receiving the error frame transmitted in sequence S1007, gateway 300 stops receiving the frame transmitted by the unauthorized ECU in the middle of receiving the data field (sequence S1008). That is, the gateway 300 does not continue to receive the frame transmitted by the unauthorized ECU because the data field from the unauthorized ECU is overwritten with the error frame and the error frame is detected.

  The fraud-sensing ECU 100a increments the fraud-sensing counter corresponding to the message ID "4" of the data frame that is the target of transmitting the error frame (sequence S1009).

  When the fraud detection counter corresponding to the message ID “4” becomes 17 or more as a result of the increment, the fraud detection ECU 100a transmits a frame (error display message) for notifying the head unit 200 of an error display. (Sequence S1010). As a result, the frame processing unit 220 of the head unit 200 performs a process for displaying an error and notifies the error via the LCD or the like. The notification of the error may be made by voice output, light emission, etc. in addition to the display on the LCD or the like.

[1.19 Effects of First Embodiment]
The fraud detection ECU described in the first embodiment determines whether the transmitted frame (data frame) is a fraudulent frame by using the regular ID list for the ID field of the frame. As a result, since the fraud can be determined by the ID field in the data frame, the fraud frame is interpreted by the existing node (that is, the ECU other than the fraud detection ECU and the fraud ECU), and the process corresponding to the frame is executed. Can be stopped. Further, since the determination can be made only by receiving up to the ID field following the SOF at the head of the data frame, it is possible to suppress the bus traffic as compared with the case where the rear part of the data frame or the like is received for the determination.

  Further, the fraud detection ECU counts the number of times the error frame is transmitted by using the fraud detection counter, so that the transmission error counter in the node that transmits the fraudulent message ID due to the reception of the error frame is in a passive state if the CAN protocol is followed. It can be detected that the upper limit value to be changed to is reached. This makes it possible to determine whether or not the node transmitting the invalid message ID complies with the CAN protocol error counter specifications.

  Further, by using only the fraud-sensing ECU as the node for determining the fraudulent frame, the influence on the existing network configuration can be minimized, and the processing amount and power consumption amount of the entire system can be suppressed. ..

(Embodiment 2)
Hereinafter, as an embodiment of the present disclosure, a fraud handling method for preventing execution of a process based on a fraudulent frame in another node (ECU) based on a data range permitted for each message ID. The in-vehicle network system 11 including the realized fraud detection ECU will be described.

[2.1 Overall Configuration of In-Vehicle Network System 11]
FIG. 19 is a diagram showing the overall configuration of the vehicle-mounted network system 11 according to the second embodiment. The in-vehicle network system 11 is a modification of the in-vehicle network system 10 described in the first embodiment. The in-vehicle network system 11 includes buses 500a and 500b, fraud detection ECUs 2100a and 2100b, a head unit 200, a gateway 300, and nodes such as ECUs 400a to 400d connected to various devices, which are connected to the bus. Composed of. Among the constituent elements of the vehicle-mounted network system 11, constituent elements having the same functions as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

  The fraud detection ECUs 2100a and 2100b are ECUs that are connected to the buses 500a and 500b, respectively, and determine whether the frames transmitted by the ECUs 400a to 400d are fraudulent, and if they are fraudulent, transmit an error frame. is there.

[2.2 Configuration of Fraud Detection ECU 2100a]
FIG. 20 is a configuration diagram of the fraud detection ECU 2100a. The fraud detection ECU 2100a includes a frame transmission/reception unit 160, a frame interpretation unit 2150, a fraud frame detection unit 2130, a data range list holding unit 2120, a fraud detection counter holding unit 110, and a frame generation unit 140. It Each of these components is a functional component, and each function thereof is realized by a communication circuit in the fraud detection ECU 2100a, a processor that executes a control program stored in the memory, a digital circuit, or the like. The fraud-sensing ECU 2100a is a modification of the fraud-sensing ECU 100a shown in the first embodiment, and the components having the same functions as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The fraud detection ECU 2100b has the same configuration as the fraud detection ECU 2100a.

  The frame interpretation unit 2150 is a modification of the frame interpretation unit 150 described in the first embodiment, receives the frame value from the frame transmission/reception unit 160, and maps it to each field in the frame format defined by the CAN protocol. To interpret. The value (data) determined to be the data field when the frame is determined to be the data frame is transferred to the unauthorized frame detection unit 2130 together with the ID (message ID) in the ID field. Further, when the frame interpretation unit 2150 determines that the frame does not conform to the CAN protocol, it notifies the frame generation unit 140 to transmit an error frame. When the frame interpretation unit 2150 receives an error frame, that is, when it interprets that the value in the received frame is an error frame, it discards the frame thereafter, that is, stops interpretation of the frame. To do.

  The unauthorized frame detection unit 2130 is a modification of the unauthorized frame detection unit 130 described in the first embodiment, receives the message ID notified from the frame interpretation unit 2150, and the value (data) of the data field. It is determined whether or not the value corresponds to a predetermined condition indicating fraud. That is, the fraudulent frame detection unit 2130 functions as a so-called determination unit that determines whether or not the content of the predetermined field in the received frame satisfies a predetermined condition indicating fraud. The predetermined condition indicating this injustice is a condition that the data does not fall within the data range listed in the data range list held by the data range list holding unit 2120 in association with the message ID. The fraudulent frame detection unit 2130 determines whether or not it is fraudulent according to the data range list, which is a list defining the data range for each message ID held in the data range list holding unit 2120. When the fraudulent frame detection unit 2130 receives data outside the range indicated by the data range list, the fraudulent frame detection unit 2130 notifies the fraud detection counter holding unit 110 of the received message ID in order to increment the number of fraud detections. The control for transmitting the error display message to be received by the head unit 200 when the number of times of detecting the fraud has reached a certain number or more is as described in the first embodiment, and therefore, here, The description is omitted. Further, when the data other than the range shown in the data range list is received, the frame generation unit 140 is notified to transmit the error frame.

  The data range list holding unit 2120 holds a data range list that is a list that predefines an allowable range for data (values of data fields) included in a data frame transmitted on the bus in the vehicle-mounted network system 11 ( See FIG. 21).

[2.3 Data range list example]
FIG. 21 is a diagram showing an example of the data range list held in the data range list holding unit 2120 of the fraud detection ECU 2100a. This data range list associates each ID (message ID) with the data range allowed as the value (data) of the data field in the data frame of the message ID. In the example of FIG. 21, the data range “0 to 180” for the data frame with the message ID “1”, the data range “0 to 100” for the data frame with the message ID “2” or “4”, For the data frame with the message ID “3”, the data range “0, 1” is normal.

[2.4 Sequence related to detection of illegal frame]
Hereinafter, operations of the fraud-sensing ECUs 2100a, ECU 400a, ECU 400b, the gateway 300, etc. connected to the bus 500a when the fraudulent ECU is connected to the bus 500a of the vehicle-mounted network system 11 having the above-described configuration will be described.

  22 and 23 are sequence diagrams showing an operation example in which the fraud-sensing ECU 2100a detects a fraudulent frame (message) and prevents another ECU from performing a process corresponding to the fraudulent frame. In FIG. 22 and FIG. 23, as in the case of FIG. 18 shown in the first embodiment, the unauthorized ECU determines that the message ID is “4” and the data field (data) is “255 (0xFF)” on the bus 500a. 7 shows an example of the case of transmitting the following data frame. The same sequences as the sequences shown in the first embodiment are designated by the same reference numerals, and the description will be simplified here.

  First, the unauthorized ECU starts transmitting an unauthorized data frame (sequence S1001). Fraud detection ECU 2100a, ECU 400a, ECU 400b and gateway 300 each receive the message ID (sequence S1002). Each of the ECU 400a, the ECU 400b, and the gateway 300 checks the message ID using the received reception ID list (sequence S1003). Since the ECU 400a and the ECU 400b do not include "4" in the reception ID list held therein (see FIG. 9), the reception ends. The gateway 300 continues the reception and receives the data field (sequence S1006a) because "4" is included in the held reception ID list (see FIG. 5). Similarly, the fraud detection ECU 2100a also receives the data field (sequence S1006a).

  Following the sequence S1006a, the fraud-sensing ECU 2100a checks the data in the data field using the data range list (see FIG. 21) (sequence S2001). That is, the fraud detection ECU 2100a determines whether or not the content of the ID field in the transmitted frame corresponds to a predetermined condition indicating fraud (not falling within the range of data described in the data range list). The fraud-sensing ECU 2100a determines that the data frame list is not a value of "255 (0xFF)" corresponding to the ID "4", and thus determines that the data frame is an invalid data frame, and then starts preparation for issuing an error frame. Yes (sequence S1005).

  While the fraud-sensing ECU 2100a prepares to issue an error frame, the fraudulent ECU sequentially sends the CRC field (CRC sequence and CRC delimiter), which is a portion after the data field, on the bus 500a bit by bit. .. The gateway 300 starts receiving this CRC field (sequence S2002).

  Next, preparation for issuing the error frame is completed, and the fraud detection ECU 2100a transmits the error frame (sequence S1007). When the transmission of this error frame is started, the middle part of the CRC sequence of the frame being transmitted from the unauthorized ECU is overwritten by the error frame (priority dominant bit string) on the bus 500a.

  Upon receiving the error frame transmitted in sequence S1007, the gateway 300 stops receiving the data frame transmitted by the unauthorized ECU in the middle of receiving the CRC field including the CRC sequence (sequence S2003). That is, since the CRC sequence from the unauthorized ECU is overwritten with the error frame and the gateway 300 detects the error frame, the gateway 300 does not continue to receive the data frame transmitted by the unauthorized ECU.

  The fraud-sensing ECU 2100a increments the fraud-sensing counter corresponding to the ID "4" of the data frame that is the target of transmitting the error frame (sequence S1009). When the fraud detection counter corresponding to ID “4” becomes 17 or more as a result of the increment, the fraud detection ECU 2100a transmits an error display message (sequence S1010).

[2.5 Effects of Second Embodiment]
The fraud detection ECU described in the second embodiment determines whether or not the transmitted frame is a fraudulent frame using the data range list for the ID field and the data field of the frame (data frame). This makes it possible to determine the fraud by the combination of the ID field and the data field in the data frame, so that the fraudulent frame is interpreted by the existing ECU (that is, the ECU other than the fraud detection ECU and the fraudulent ECU) and corresponds to the frame. It is possible to prevent the processing from being executed. Further, since the determination can be made only by receiving the data field of the data frame, it is possible to suppress the bus traffic as compared with the case of receiving the rear part of the data frame and making the determination.

  Further, the fraud detection ECU counts the number of times the error frame is transmitted by using the fraud detection counter, so that the transmission error counter in the node that transmits the fraudulent message ID due to the reception of the error frame is in a passive state if the CAN protocol is followed. It can be detected that the upper limit value to be changed to is reached. This makes it possible to determine whether or not the node transmitting the invalid message ID complies with the CAN protocol error counter specifications.

  Further, by using only the fraud-sensing ECU as the node for determining the fraudulent frame, the influence on the existing network configuration can be minimized, and the processing amount and power consumption amount of the entire system can be suppressed. .

(Embodiment 3)
Hereinafter, as an embodiment of the present disclosure, a message authentication code (MAC: Message Authentication Code) calculated from a message ID, data, and a counter value is used to execute a process based on an invalid frame in another node (ECU). An in-vehicle network system 12 including a fraud-sensing ECU that implements a fraud-handling method for preventing such a situation will be described.

[3.1 Overall Configuration of In-Vehicle Network System 12]
FIG. 24 is a diagram showing the overall configuration of the vehicle-mounted network system 12 according to the third embodiment. The vehicle-mounted network system 12 is a modification of the vehicle-mounted network system 10 described in the first embodiment. The vehicle-mounted network system 12 includes buses 500a and 500b, fraud detection ECUs 3100a and 3100b, a head unit 200, a gateway 300, and nodes such as ECUs 3400a to 3400d connected to various devices, which are connected to the bus. Composed of. Among the constituent elements of the in-vehicle network system 12, constituent elements having the same functions as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

  The fraud detection ECUs 3100a and 3100b are ECUs that are connected to the buses 500a and 500b, respectively, and determine whether the frames transmitted by the ECUs 3400a to 3400d and the like are fraudulent, and if they are fraudulent, transmit an error frame. is there.

  The ECUs 3400a to 3400d are connected to any of the buses, and are also connected to the engine 401, the brake 402, the door opening/closing sensor 403, and the window opening/closing sensor 404, respectively. Each of the ECUs 3400a to 3400d acquires the state of the connected device (engine 401 or the like) and periodically transmits a data frame indicating the state to the network (that is, the bus). A message authentication code (MAC) derived from a message ID, a data value, and a counter value that is incremented for each transmission is added to the data field of the data frame to be transmitted.

[3.2 Configuration of ECU 3400a]
FIG. 25 is a configuration diagram of the ECU 3400a. The ECU 3400a includes a frame transmission/reception unit 460, a frame interpretation unit 450, a reception ID determination unit 430, a reception ID list holding unit 440, a frame processing unit 410, a frame generation unit 3420, a data acquisition unit 470, and a MAC generation. A unit 3410, a MAC key holding unit 3430, and a counter holding unit 3440 are included. Each of these components is a functional component, and each function thereof is realized by a communication circuit in the ECU 3400a, a processor that executes a control program stored in the memory, a digital circuit, or the like. The ECU 3400a is a modification of the ECU 400a shown in the first embodiment, and components having the same functions as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

  The frame generation unit 3420 is a modification of the frame generation unit 420 shown in the first embodiment. The frame generation unit 3420 composes an error frame according to the notification instructing the transmission of the error frame notified from the frame interpretation unit 450, and notifies the frame transmission/reception unit 460 to transmit the error frame. Also, the frame generation unit 3420 notifies the MAC generation unit 3410 of the value of the data notified by the data acquisition unit 470 and the predetermined message ID, and receives the calculated MAC. The frame generation unit 3420 configures a frame so as to include a predetermined message ID, the value of the data notified from the data acquisition unit 470, and the MAC received from the MAC generation unit 3410 (see FIG. 26), and transmits and receives the frame. Notify the section 460.

  The MAC generation unit 3410 holds, in the MAC key holding unit 3430, a value (combined value) obtained by combining the message ID and the data value notified from the frame generation unit 3420 with the counter value held in the counter holding unit 3440. The MAC key is calculated (derived by calculation) using the MAC key, and the MAC that is the calculated result is notified to the frame generation unit 3420. Here, HMAC (Hash-based Message Authentication Code) (see Non-Patent Document 2) is adopted as the MAC calculation method, and the MAC key is padded to a predetermined block (for example, 4 Bytes) with respect to the combined value described above. Is used, and the first 4 bytes of the calculation result that appears are the MAC. Note that, here, the combined value used for calculating the MAC uses the message ID, the value of the data, and the counter value held by the counter holding unit 3440, but any one of these three is used. Alternatively, the MAC may be calculated using a combination of the two.

  The MAC key holding unit 3430 holds the MAC key necessary for calculating the MAC.

  The counter holding unit 3440 holds the counter value necessary for calculating the MAC. The counter value is incremented every time the data frame is normally transmitted by the frame transmitting/receiving unit 460.

  Each of ECUs 3400b to 3400d is a modification of each of ECUs 400b to 400d shown in the first embodiment, and basically has the same configuration as that of ECU 3400 described above. However, the reception ID list stored in the reception ID list storage unit 440 may have different contents for each ECU. For example, the ECU 3400a and the ECU 3400b hold the reception ID list illustrated in FIG. 9, and the ECU 3400c and the ECU 3400d hold the reception ID list illustrated in FIG. Further, the processing content of the frame processing unit 410 is different for each ECU as shown in the first embodiment. The contents of the frame transmitted by each of the ECUs 3400a to 3400d will be described below with reference to FIGS.

[3.3 Transmission Frame Example of ECU 3400a Related to Engine]
FIG. 26 is a diagram showing an example of an ID (message ID) and a data field (data) in a data frame transmitted from the ECU 3400a connected to the engine 401. The message ID of the frame transmitted by the ECU 3400a is "1". In the figure, the data is divided into blanks for each byte, the first 1 byte represents a speed (km/hour), the next 1 byte represents a counter value, and the next 4 bytes represents a MAC. In the example of FIG. 26, the MAC is expressed in hexadecimal. The hourly speed (km/hour) of the first 1 byte takes a value in the range of 0 (km/hour) at the lowest to 180 (km/hour) at the highest. From the top row to the bottom row in FIG. 26, message IDs and data corresponding to each frame sequentially transmitted from the ECU 3400a are illustrated, and the counter value is gradually increased and the speed is accelerated from 0 km/hour to 1 km/hour. It shows the situation.

[3.4 Transmission Frame Example of ECU 3400b for Braking]
FIG. 27 is a diagram showing an example of an ID (message ID) and a data field (data) in a data frame transmitted from the ECU 3400b connected to the brake 402. The message ID of the frame transmitted by the ECU 3400b is “2”. In the figure, the data is divided into blanks for each 1 byte, the first 1 byte represents the degree of braking (%), the next 1 byte represents the counter value, and the next 4 bytes represent the MAC. Represent Note that in the example of FIG. 27, the MAC is expressed in hexadecimal. The degree of braking of the first 1 byte is 0 (%) when the brake is not applied at all, and 100 (%) when the brake is applied to the maximum. From the top row to the bottom row in FIG. 27, message IDs and data corresponding to each frame sequentially transmitted from the ECU 3400b are illustrated, the counter value gradually increases, and the brake gradually weakens from 100%. It shows the situation.

[3.5 Transmission Frame Example of ECU 3400c Related to Door Opening/Closing Sensor]
FIG. 28 is a diagram showing an example of an ID (message ID) and a data field (data) in a data frame transmitted from the ECU 3400c connected to the door opening/closing sensor 403. The message ID of the frame transmitted by the ECU 3400c is “3”. In the figure, the data is divided into blanks for each byte, the first 1 Byte represents the open/closed state of the door, the next 1 Byte represents the counter value, and the next 4 Bytes represents the MAC. In addition, in the example of FIG. 28, the MAC is represented by a hexadecimal number. The open/closed state of the first 1-byte door is "1" when the door is open and "0" when the door is closed. 28 illustrates the message IDs and data corresponding to the frames sequentially transmitted from the ECU 3400c from the upper row to the lower row in FIG. 28, in which the counter value gradually increases and the door is gradually closed from the open state. It shows how it moved to.

[3.6 Transmission Frame Example of ECU 3400d Related to Window Opening/Closing Sensor]
FIG. 29 is a diagram showing an example of an ID (message ID) and a data field (data) in a data frame transmitted from the ECU 3400d connected to the window opening/closing sensor 404. The message ID of the frame transmitted by the ECU 3400d is “4”. In the figure, the data is represented by dividing each byte into blanks. The leading 1 Byte represents the open/closed state of the window as a percentage (%), the next 1 byte represents the counter value, and the next 4 bytes represent the MAC. Represent In the example of FIG. 29, the MAC is expressed in hexadecimal. The open/closed state of the first 1-byte window is 0 (%) when the window is completely closed, and 100 (%) when the window is fully open. 29 shows message IDs and data corresponding to each frame sequentially transmitted from the ECU 3400d from the top row to the bottom row of FIG. 29, the counter value gradually increases, and the window gradually opens from the closed state. It shows the situation.

[3.7 Configuration of Fraud Detection ECU 3100a]
FIG. 30 is a configuration diagram of the fraud detection ECU 3100a. The fraud detection ECU 3100a includes a frame transmission/reception unit 160, a frame interpretation unit 3150, a fraudulent MAC detection unit 3130, a MAC key holding unit 3180, a counter holding unit 3190, a frame generation unit 140, a MAC generation unit 3170, and fraud. It is composed of the detection counter holding unit 110. Each of these components is a functional component, and each function thereof is realized by a communication circuit in the fraud detection ECU 3100a, a processor that executes a control program stored in the memory, a digital circuit, or the like. The fraud-sensing ECU 3100a is a modification of the fraud-sensing ECU 100a shown in the first embodiment, and components having the same functions as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The fraud detection ECU 3100b has the same configuration.

  The frame interpretation unit 3150 is a modification of the frame interpretation unit 150 described in the first embodiment, receives the frame value from the frame transmission/reception unit 160, and maps it to each field in the frame format defined by the CAN protocol. To interpret. The value (data) determined to be the data field when the frame is determined to be the data frame is transferred to the unauthorized MAC detection unit 3130 together with the ID (message ID) in the ID field. When the frame interpretation unit 3150 determines that the frame does not conform to the CAN protocol, it notifies the frame generation unit 140 to transmit an error frame. Further, when the frame interpretation unit 3150 receives an error frame, that is, when it interprets that the value in the received frame is an error frame, it discards the frame thereafter, that is, stops interpretation of the frame. To do.

  The illegal MAC detection unit 3130 has a function of receiving the message ID notified from the frame interpretation unit 3150 and the value (data) of the data field and verifying the MAC in the data field. The unauthorized MAC detection unit 3130 notifies the notified message ID and the value of the data field to the MAC generation unit 3170, and acquires the MAC generated by the MAC generation unit 3170. The fraudulent MAC detection unit 3130 determines whether or not the data in the data field meets a predetermined condition indicating fraud. That is, the fraudulent MAC detection unit 3130 functions as a so-called determination unit that determines whether or not the content of the predetermined field in the received frame satisfies a predetermined condition indicating fraud. The predetermined condition indicating this injustice is that the verification in a predetermined verification processing procedure (procedure including generation of MAC, comparison of MAC, etc.) fails, that is, the MAC included in the data is the MAC generation unit 3170. The condition is that it is different from the MAC generated by. The unauthorized MAC detection unit 3130 compares the MAC acquired from the MAC generation unit 3170 with the MAC in the data field to determine whether the MAC is unauthorized (that is, verify the MAC). When the values of both MACs do not match as a result of comparison, the received message ID is notified to the fraud detection counter holding unit 110 in order to increment the number of fraud detections. The control for transmitting the error display message to be received by the head unit 200 when the number of times of detecting fraud reaches a certain number or more is as described in the first embodiment. The description is omitted. Further, as a result of the comparison of the values of the two MACs, if they do not match, the frame generation unit 140 is notified to transmit an error frame. As a result of the comparison of the MAC values, if they match, the MAC generation unit 3170 is notified to increment the counter value held by the counter holding unit 3190 and corresponding to the message ID.

  The MAC generation unit 3170 uses the message ID notified by the unauthorized MAC detection unit 3130 to acquire the corresponding MAC key from the MAC key holding unit 3180 and the corresponding counter from the counter holding unit 3190. The MAC generation unit 3170 uses the MAC key acquired from the MAC key storage unit 3180 for the value of the data field (the value of the first 1 Byte) notified by the unauthorized MAC detection unit 3130 and the counter value acquired from the counter storage unit 3190. Is used to calculate (derived by calculation), and the calculated MAC is notified to the unauthorized MAC detection unit 3130. The fraud detection ECUs 3100a and 3100b and the ECUs 3400a to 3400d use the same algorithm for calculating the MAC using the MAC key.

  The MAC key holding unit 3180 holds the MAC key necessary for calculating the MAC in association with each message ID. The MAC key held by the MAC key holding unit 3180 has a different value for each associated message ID. Note that the MAC key used in the ECU and the fraud detection ECU may be a different key for each transmission node, assuming that one transmission node transmits a frame for each of a plurality of message IDs. As the MAC key, for example, the same value may be used for frames transmitted on the same bus, or the same key (value) may be used on different buses. The same key may be used for each vehicle, the same key may be used for the same vehicle type, the same key may be used for each same manufacturer, or the same key may be used for different manufacturers.

  The counter holding unit 3190 holds the counter value required for calculating the MAC value for each message ID. This counter value is incremented when the frame is normally received (that is, when both MACs compared by the unauthorized MAC detection unit 3130 match).

[3.8 Example of Counter Value]
FIG. 31 is a diagram showing an example of the counter value for each message ID held in the counter holding unit 3190. In the figure, the counter with the message ID “1” is once, the counter with the message ID “2” is 10 times, the counter with the message ID “3” is 15 times, and the counter with the message ID “4” is 100 times. Shows each time. The counter value corresponding to each message ID represents the number of times that the frame including the message ID is normally received.

[3.9 Sequence Related to Detection of Illegal Frame]
Hereinafter, in the case where an unauthorized ECU is connected to the bus 500a of the vehicle-mounted network system 12 having the above-described configuration, the operations of the fraud detection ECU 3100a, the ECU 3400a, the ECU 3400b, the gateway 300, etc. connected to the bus 500a will be described.

  32 and 33 are sequence diagrams showing an operation example in which the fraud-sensing ECU 3100a detects a fraudulent frame (message) and prevents another ECU from performing a process corresponding to the fraudulent frame. 32 and 33, similar to the case of FIG. 18 shown in the first embodiment and FIGS. 22 and 23 shown in the second embodiment, an example in which an unauthorized ECU is connected to the bus 500a is shown. There is. This unauthorized ECU transmits a data frame in which the message ID is “4” and the data field (data) is “0xFF FF FFFFFFFFFF” (6 bytes). The same sequence as the sequence shown in the first or second embodiment is denoted by the same reference numeral, and the description is simplified here.

  First, the unauthorized ECU starts transmitting the above-described unauthorized data frame (sequence S1001a). Fraud detection ECU 3100a, ECU 3400a, ECU 3400b, and gateway 300 each receive the message ID (sequence S1002). Each of the ECU 3400a, the ECU 3400b, and the gateway 300 checks the message ID using the held reception ID list (sequence S1003). The ECU 3400a and the ECU 3400b terminate the reception because the reception ID list held by each of them does not include "4" (see FIG. 9). The gateway 300 continues to receive and receives the data field (sequence S1006a) because "4" is included in the held reception ID list (see FIG. 5). Similarly, the fraud detection ECU 3100a also receives the data field (sequence S1006a).

  Following sequence S1006a, fraud detection ECU 3100a verifies (checks) the MAC included in the data in the data field (sequence S3001). That is, the fraud detection ECU 3100a determines whether or not the content of the ID field in the transmitted frame satisfies a predetermined condition indicating fraud (failing to verify the MAC). The fraud detection ECU 3100a calculates the MAC of 6 bytes in the data field of the data field in the data frame transmitted by the fraudulent ECU using the MAC of 4 bytes in the latter half and the MAC key and counter corresponding to the message ID “4”. The MAC is verified by comparing with. Since the result of this comparison does not match and the verification fails, the fraud-sensing ECU 3100a determines that the data frame is fraudulent, and subsequently starts preparation for issuing an error frame (sequence S1005).

  While the fraud-sensing ECU 3100a is preparing to issue an error frame, the gateway 300 starts receiving the CRC field (sequence S2002).

  Next, preparation for issuing the error frame is completed, and the fraud-sensing ECU 3100a transmits the error frame (sequence S1007). When the transmission of the error frame is started, the middle part of the CRC sequence of the frame being transmitted from the unauthorized ECU is overwritten by the error frame on the bus 500a.

  Upon receiving the error frame transmitted in sequence S1007, gateway 300 stops receiving the data frame transmitted by the unauthorized ECU in the middle of receiving the CRC field including the CRC sequence (sequence S2003).

  The fraud detection ECU 3100a increments the fraud detection counter corresponding to the ID “4” of the data frame that is the target of transmitting the error frame (sequence S1009). When the fraud detection counter corresponding to ID “4” becomes 17 or more as a result of the increment, the fraud detection ECU 3100a transmits an error display message (sequence S1010).

[3.10 Effects of Third Embodiment]
The fraud-sensing ECU shown in the third embodiment determines whether or not the transmitted frame is a fraudulent frame by verifying the MAC included in the data field of the frame (data frame). As a result, it is possible to prevent the existing ECU (that is, the ECU other than the fraud detection ECU and the fraudulent ECU) from interpreting the fraudulent frame and executing the process corresponding to the frame. Further, since the determination can be made only by receiving the data field of the data frame, it is possible to suppress the bus traffic as compared with the case of receiving the rear part of the data frame and making the determination.

  Further, the fraud detection ECU counts the number of times the error frame is transmitted by using the fraud detection counter, so that the transmission error counter in the node that transmits the fraudulent message ID due to the reception of the error frame is in a passive state if the CAN protocol is followed. It can be detected that the upper limit value to be changed to is reached. This makes it possible to determine whether or not the node transmitting the invalid message ID complies with the CAN protocol error counter specifications.

  Further, since only the fraud-sensing ECU is used as the node for verifying the MAC, it is not necessary to perform the validation by an ECU other than the fraud-sensing ECU, and the processing amount and power consumption can be suppressed as a whole system.

(Other embodiments)
As described above, the first to third embodiments have been described as examples of the technology according to the present disclosure. However, the technology according to the present disclosure is not limited to this, and is also applicable to the embodiment in which changes, replacements, additions, omissions, etc. are appropriately made. For example, the following modified examples are also included in one embodiment of the present disclosure.

  (1) In the above embodiment, an example in which the frames are periodically transmitted by the ECUs 400a to 400d or the ECUs 3400a to 3400d has been described, but the frames may be transmitted as an event notifying a state change. For example, the ECU may not transmit the open/closed state of the door periodically, but may transmit the frame only when the open/closed state of the door changes. The ECU may also transmit the frame periodically and when a state change occurs.

  (2) In the third embodiment, an example in which the MAC is calculated from the data value and the counter value has been shown, but the MAC may be calculated only from the data value. Further, the MAC may be calculated only from the counter value. The size of the MAC included in the frame is not limited to 4 bytes, and may be different for each transmission. Similarly, the size of the data value such as the speed and the size of the counter value are not limited to 1 byte. Further, the frame does not necessarily have to include the counter value.

  (3) In the third embodiment, an example in which the counter value is incremented for each transmission has been described, but the counter value may be a value that is automatically incremented according to time. Further, the value of the time itself may be used instead of the counter. That is, if the MAC is generated based on the variable (counter, time, etc.) that changes every time the data frame is transmitted, it becomes possible to make illegal decoding of the MAC difficult. Further, in the third embodiment, the MAC generation unit 3170 in the fraud detection ECU calculates the MAC value from the message ID, the first 1 Byte of the data field, and the counter value of the counter holding unit 3190. Alternatively, the MAC value may be calculated from the message ID, the first 1 Byte of the data field, and the counter value which is the next 1 Byte of the data field. Further, the counter value of the counter holding unit 3190 may be updated so as to match the counter value in the data field determined not to be illegal.

  (4) In the above embodiment, the data frame in the CAN protocol is described in the standard ID format, but it may be in the extended ID format. In the case of the extended ID format, the base ID at the ID position in the standard ID format and the extended ID are combined to represent the ID (message ID) in 29 bits. Therefore, this 29-bit ID is the ID in the above-described embodiment. It may be treated as (message ID).

  (5) In the above embodiment, the MAC calculation algorithm is HMAC, but CBC-MAC (Cipher Block Chaining Message Authentication Code) or CMAC ((Cipher-based MAC) may be used. The padding used for zero padding, ISO10126, PKCS#1, PKCS#5, PKCS#7, and any other padding method that requires the block data size for calculation. As for the method of changing the size to, the padding may be performed at any of the beginning, the end, and the middle.The data used for the MAC calculation is continuous data (for example, continuous data for 4 bytes). Alternatively, the data may be collected and combined one bit at a time according to a specific rule.

  (6) In the above embodiment, the in-vehicle network is shown as an example of the network communication system that communicates according to the CAN protocol. The technology according to the present disclosure is not limited to an in-vehicle network, and is also applicable to networks such as robots and industrial equipment, and network communication systems that communicate according to a CAN protocol other than the in-vehicle network. Further, the CAN protocol has a broad meaning including a CANO Pen used in an embedded system in an automation system, or a derivative protocol such as TTCAN (Time-Triggered CAN) or CANFD (CAN with Flexible Data Rate). Should be treated as

  (7) In the above embodiment, an example in which an unauthorized ECU is connected to the bus has been described, but an existing ECU such as the ECUs 400a to 400d or ECUs 3400a to 3400d may act as an unauthorized ECU due to some factor. . Even in that case, the fraud-sensing ECU appropriately detects the fraudulent frame and transmits the error frame as shown in the above-described embodiment, so that another ECU processes the fraudulent frame. Can be stopped.

  (8) In the second embodiment, the data range of the received data frame is allowed for each message ID by using the data range list in which the message ID is associated with the allowed data range. Whether or not the message ID is included is included in the data range list. However, the message ID is not included in the data range list, and the data range that is commonly allowed for all message IDs (for example, " 0 to 180”) may be set and whether or not the message ID is illegal may be determined. Further, the data range list held by the fraud-sensing ECU may correspond to the message ID and the data range that can be transmitted on the bus to which the fraud-sensing ECU is connected. As a result, the data range list can be used also as the regular ID list shown in the first embodiment. By utilizing this, the fraud detection ECU shown in the second embodiment may also check the message ID shown in the first embodiment (sequence S1004).

  (9) Instead of the data range list in which the message ID and the allowed data range shown in the second embodiment are associated, the fraud detection ECU associates the message ID with the allowed data length. It is also possible to use the attached data length list. In this case, the fraud-sensing ECU determines whether or not the value of the control field of the received data frame satisfies a predetermined condition indicating fraud. The predetermined condition indicating this injustice is that the data length (DLC) in the control field is not the data length associated with the message ID in the data length list. The fraud-sensing ECU determines whether or not the received DCL is fraudulent based on whether or not the received DCL has a data length that is allowed for each message ID in the data length list.

  (10) In the above-described embodiment, the description has been made by paying particular attention to the data frame, but the fraud detection ECU can also detect a certain fraud in the remote frame. For example, the fraud-sensing ECU may determine whether or not the message ID in the received remote frame is fraudulent using the regular ID list shown in the first embodiment. Further, whether the fraud detection ECU is fraudulent based on whether the data length (DLC) in the control field in the remote frame received using the data length list described above is the data length allowed for each message ID. May be determined. Further, the error frame transmitted when the fraud detection ECU shown in the above embodiment detects fraud by receiving the fraudulent frame is preferably transmitted promptly after the fraud detection. Note that it is useful for the fraud-sensing ECU to transmit the error frame after the fraud is detected and before the end of the CRC sequence of the fraudulent frame is transmitted. As a result, the other ECU stops processing of the illegal frame due to the detection of the error frame or the error detection in the CRC check. The remote frame also includes a message ID, a control field, and a CRC sequence like the data frame.

  (11) In the above embodiment, the fraud-sensing ECU transmits the error display message under a certain condition, but the error display message may not be transmitted. In this case, the ECUs such as the gateway and the head unit do not need to hold the configuration (such as the reception ID list for receiving the error display message) particularly corresponding to the fraud detection ECU. It should be noted that the fraud-sensing ECU may notify itself of an error when it is equipped with a speaker, a display, or the like instead of transmitting an error display message, or may record an error log in a storage medium or the like.

  (12) The fraudulent frame detection unit and fraudulent MAC detection unit described in the above embodiments may be implemented in hardware called a CAN controller or firmware that operates on a processor that operates by connecting to the CAN controller. Further, the MAC key holding unit, the counter holding unit, the regular ID list holding unit, and the data range list holding unit are provided in a hardware register called a CAN controller, or firmware operating on a processor operating by connecting to the CAN controller. It may be stored.

  (13) Each of the ECUs (including the gateway and the head unit) in the above embodiments is a device including a digital circuit such as a processor and a memory, an analog circuit, a communication circuit, etc. Other hardware components such as a keyboard, a mouse, etc. may be included. Further, instead of the control program stored in the memory being executed by the processor and realizing the function by software, the function may be realized by dedicated hardware (digital circuit or the like).

  (14) Part or all of the constituent elements of each device in the above-described embodiments may be composed of one system LSI (Large Scale Integration). The system LSI is an ultra-multifunctional LSI manufactured by integrating a plurality of constituent parts on one chip, and specifically, is a computer system including a microprocessor, ROM, RAM and the like. . A computer program is recorded in the RAM. The system LSI achieves its function by the microprocessor operating according to the computer program.

  Further, each part of the constituent elements of each of the above devices may be individually made into one chip, or may be made into one chip so as to include a part or all.

  Although the system LSI is used here, it may be called IC, LSI, super LSI, or ultra LSI depending on the degree of integration. Further, the method of circuit integration is not limited to LSI, and it may be realized by a dedicated circuit or a general-purpose processor. A programmable programmable gate array (FPGA) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

  Further, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. The application of biotechnology is possible.

  (15) Part or all of the constituent elements of each of the above devices may be configured with an IC card that can be attached to or detached from each device or a single module. The IC card or the module is a computer system including a microprocessor, ROM, RAM and the like. The IC card or the module may include the above super-multifunctional LSI. The IC card or the module achieves its function by the microprocessor operating according to the computer program. This IC card or this module may be tamper resistant.

  (16) As one aspect of the present disclosure, a method such as the above-described fraud handling method may be used. Further, it may be a computer program that realizes these methods by a computer, or may be a digital signal including the computer program.

  In addition, as one aspect of the present disclosure, a recording medium that can read the computer program or the digital signal by a computer, for example, a flexible disk, a hard disk, a CD-ROM, a MO, a DVD, a DVD-ROM, a DVD-RAM, a BD ( It may be recorded on a Blu-ray (registered trademark) Disc), a semiconductor memory, or the like. Further, it may be the digital signal recorded on these recording media.

  As one aspect of the present disclosure, the computer program or the digital signal may be transmitted via an electric communication line, a wireless or wired communication line, a network typified by the Internet, a data broadcast, or the like.

  In addition, as one aspect of the present disclosure, a computer system including a microprocessor and a memory, wherein the memory records the computer program, and the microprocessor may operate according to the computer program. .

  Further, the program or the digital signal is recorded on the recording medium and transferred, or the program or the digital signal is transferred via the network or the like, thereby being implemented by another independent computer system. You can do that.

  (17) A form realized by arbitrarily combining each component and function shown in the above-mentioned embodiment and the above-mentioned modification is also contained in the scope of the present disclosure.

  The present disclosure can be used to suppress the influence of an unauthorized ECU in an in-vehicle network system or the like.

10, 11, 12 In-vehicle network system 100a, 100b, 2100a, 2100b, 3100a, 3100b Fraud detection electronic control unit (fraud detection ECU)
110 Fraud detection counter holding unit 120 Regular ID list holding unit 130, 2130 Fraud frame detection unit 140, 230, 320, 420, 3420 Frame generation unit 150, 260, 350, 450, 2150, 3150 Frame interpretation unit 160, 270, 360 , 460 frame transmission/reception unit 200 head unit 210 display control unit 220, 410 frame processing unit 240, 330, 430 reception ID determination unit 250, 340, 440 reception ID list holding unit 300 gateway 310 transfer processing unit 370 transfer rule holding unit 400a, 400b, 400c, 400d, 3400a, 3400b, 3400c, 3400d Electronic control unit (ECU)
401 engine 402 brake 403 door open/close sensor 404 window open/close sensor 470 data acquisition unit 500a, 500b, 500c bus 2120 data range list holding unit 3130 unauthorized MAC detection unit 3410, 3170 MAC generation unit 3430, 3180 MAC key holding unit 3440, 3190 counter Holding part

Claims (4)

A fraud handling method used in a network communication system including a plurality of electronic control units that communicate via a bus according to a CAN (Controller Area Network) protocol,
A first determination step of determining whether or not the content of the predetermined field in the frame in which the transmission is started satisfies a predetermined condition indicating fraud,
A transmission step of transmitting an error frame before the end of the frame is transmitted when it is determined that the content of the predetermined field of the frame satisfies the predetermined condition in the first determination step;
A recording step of recording the number of times the error frame is transmitted in the transmitting step, for each ID represented by the content of the ID field included in the frame to which the error frame is transmitted,
A second determination step of determining that the ID is illegal when the number of times of each ID recorded by the recording step exceeds a predetermined number,
The predetermined field is a field indicating an ID,
In the first determining step, the ID represented by the content of the predetermined field is compared with one or more IDs indicated by predetermined ID list information to determine whether the predetermined condition is satisfied. Make a decision,
In the first determining step, the ID represented by the content of the predetermined field is compared with all one or more IDs indicated by the ID list information, and if they do not match, it is determined that the predetermined condition is satisfied ,
The predetermined number of times indicates a value to be transited to a passive state defined corresponding to the handling rule of the transmission error counter in the CAN protocol,
In the second determination step, when the number of times for each ID recorded in the recording step exceeds the predetermined number of times, the electronic control unit that has transmitted the frame of the ID that has exceeded the predetermined number of times is in the passive state. A method for dealing with fraud that determines that the electronic control unit does not transition to . The fraud handling method according to claim 1, wherein in the transmitting step, the transmission of the error frame is performed before the end of the CRC sequence in the frame is transmitted. A fraud detection electronic control unit connected to a bus used by a plurality of electronic control units communicating according to CAN (Controller Area Network) protocol,
A first determination unit that determines whether or not the content of a predetermined field in the frame in which the transmission is started satisfies a predetermined condition indicating fraud,
A transmitter that transmits an error frame before the end of the frame is transmitted when the first determination unit determines that the content of the predetermined field of the frame satisfies the predetermined condition;
A recording unit that records the number of times an error frame is transmitted by the transmitting unit, for each ID represented by the content of the ID field included in the frame that is the target of transmitting the error frame,
A second determination unit that determines that the ID is illegal when the number of times each ID recorded by the recording unit exceeds a predetermined number,
The predetermined field is a field indicating an ID,
The first determination unit compares the ID represented by the content of the predetermined field with one or more IDs indicated by predetermined ID list information to determine whether or not the predetermined condition is satisfied. Make a decision,
The first determination unit compares the ID represented by the content of the predetermined field with all one or more IDs indicated by the ID list information, and when they do not match, determines that the predetermined condition is satisfied ,
The predetermined number of times indicates a value to be transited to a passive state defined corresponding to the handling rule of the transmission error counter in the CAN protocol,
When the number of times each ID recorded by the recording unit exceeds the predetermined number in the second determination unit, the electronic control unit that has transmitted the frame of the ID that has exceeded the predetermined number of times is in a passive state. It is determined that it is an unauthorized electronic control unit that does not transition to
Fraud detection electronic control unit. A network communication system including a plurality of electronic control units that communicate via a bus according to a CAN (Controller Area Network) protocol,
A first determination unit that determines whether or not the content of a predetermined field in the frame in which the transmission is started satisfies a predetermined condition indicating fraud,
A transmitter that transmits an error frame before the end of the frame is transmitted when the first determination unit determines that the content of the predetermined field of the frame satisfies the predetermined condition;
A recording unit that records the number of times an error frame is transmitted by the transmitting unit, for each ID represented by the content of the ID field included in the frame that is the target of transmitting the error frame,
A second determination unit that determines that the ID is illegal when the number of times each ID recorded by the recording unit exceeds a predetermined number,
The predetermined field is a field indicating an ID,
The first determination unit compares the ID represented by the content of the predetermined field with one or more IDs indicated by predetermined ID list information to determine whether or not the predetermined condition is satisfied. Make a decision,
The first determination unit compares the ID represented by the content of the predetermined field with all one or more IDs indicated by the ID list information, and when they do not match, determines that the predetermined condition is satisfied ,
The predetermined number of times indicates a value to be transited to a passive state defined corresponding to the handling rule of the transmission error counter in the CAN protocol,
When the number of times each ID recorded by the recording unit exceeds the predetermined number in the second determination unit, the electronic control unit that has transmitted the frame of the ID that has exceeded the predetermined number of times is in a passive state. It is determined that it is an unauthorized electronic control unit that does not transition to
Network communication system.

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