WO2019003362A1

WO2019003362A1 - In-vehicle system and count updating method

Info

Publication number: WO2019003362A1
Application number: PCT/JP2017/023823
Authority: WO
Inventors: 英二石岡; 保彦阿部
Original assignee: 富士通株式会社
Priority date: 2017-06-28
Filing date: 2017-06-28
Publication date: 2019-01-03

Abstract

This in-vehicle system (1) holds an identical internal count value between a transmission-side in-vehicle device (2A) and a reception-side in-vehicle device (2B) in a vehicle (1A), and regulates a delivery sequence of data which the reception-side in-vehicle device has received from the transmission-side in-vehicle device on the basis of the internal count value. The transmission-side in-vehicle device has a communication unit (23) which selectively transmits a first signal (32) that includes an authentication value for identifying the authenticity of data to be transmitted, and a second signal (33) that includes a count value in addition to the authentication value. The reception-side in-vehicle device has an interpretation unit (24) and an updating unit (28). The interpretation unit determines whether the received signal includes the count value. The updating unit updates, on the basis of the count value, the internal count value held by the own device when the received signal includes the count value. As a result, an amount of data communication between the transmission-side in-vehicle device and the reception-side in-vehicle device can be reduced.

Description

In-vehicle system and count updating method

The present invention relates to an in-vehicle system and a count updating method.

In an in-vehicle system that connects ECUs (Electronic Control Units) mounted on a vehicle via a CAN (Controller Area Network), there is a MAC (Message Authentication Code) verification function to prevent spoofing or tampering with messages from the external environment. .

In the MAC verification function, a transmitting ECU that transmits a message calculates a MAC value from the message, and notifies the receiving ECU of the MAC value and the message. Then, the receiving ECU calculates a MAC value from the received message, performs MAC verification between the MAC value received from the transmitting ECU and the calculated MAC value, and determines the authenticity of the received message based on the verification result. Do. For example, when the MAC values match, the receiving ECU determines that the verification result is OK, and determines that the received message is authentic. Further, for example, when the MAC values do not match, the receiving-side ECU determines that the verification result is NG, and determines that the received message is not authentic.

The transmitting ECU transmits the message and the MAC value in a broadcast manner. And each ECU is in the state which can receive a message and a MAC value. However, in the receiving ECU, even when a message used in the past is subjected to a re-transmission attack of being re-sent from another device, the MAC values may coincide and the verification result may be OK. Therefore, in order to avoid such a situation, retransmission is performed by using a serial number synchronized between the transmitting ECU and the receiving ECU, and setting the MAC value to be different when the serial number is different even with the same message. You can avoid the attack.

However, when adopting a serial number, it is necessary to synchronize the serial number between the transmitting ECU and the receiving ECU. Therefore, the transmitting ECU counts up the serial number when transmitting the message, and the receiving ECU also counts up the serial number when receiving the message. As a result, synchronization of serial numbers is established between the transmitting ECU and the receiving ECU.

International Publication No. 2013/065689 JP, 2016-96419, A

However, in the in-vehicle system, when a dropout of a message occurs between the transmitting side ECU and the receiving side ECU, the receiving side ECU can not receive the message, and the serial number can not be counted up. Further, in the in-vehicle system, the serial number is reset even when the receiving ECU restarts. As a result, a serial number mismatch occurs between the transmitting ECU and the receiving ECU, and the verification result is NG due to the mismatch of the MAC values, and the received message is discarded. Therefore, in the in-vehicle system, a method of notifying the serial number from the transmitting side ECU to the receiving side ECU is adopted. In order to notify the receiving ECU of a serial number in addition to the MAC value for each message, the transmitting ECU establishes synchronization between the transmitting ECU and the receiving ECU with the received serial number.

However, in the in-vehicle system, since the transmitting side ECU notifies the receiving side ECU of the serial number for each message, the amount of data communication between the transmitting side ECU and the receiving side ECU is increased. That is, the amount of data communication between the transmitting on-vehicle apparatus as the transmitting ECU and the receiving on-vehicle apparatus as the receiving ECU increases.

An object of the present invention is to provide an on-vehicle system and the like for reducing the amount of data communication.

In one scheme, the same internal count value is held between the transmitting on-vehicle apparatus and the receiving on-vehicle apparatus in the vehicle, and the receiving on-vehicle apparatus receives from the transmitting on-vehicle apparatus based on the internal count value. It is an in-vehicle system which specifies the delivery order of the collected data. The transmitting on-vehicle apparatus includes a first signal including an authentication value identifying authenticity of data to be transmitted, and a communication unit that selectively transmits a second signal including a count value in addition to the authentication value. . The receiving in-vehicle apparatus determines whether the received signal includes the count value, and when the received signal includes the count value, the apparatus holds the signal based on the count value. And an update unit that updates the internal count value.

Reduce the amount of data communication.

FIG. 1 is a block diagram showing an example of the in-vehicle system of the present embodiment. FIG. 2 is an explanatory view showing an example of a hardware configuration in the ECU. FIG. 3 is an explanatory view showing an example of the configuration of a data frame. FIG. 4 is an explanatory view showing an example of the configuration of the first authentication frame. FIG. 5 is an explanatory view showing an example of the configuration of the second authentication frame. FIG. 6 is an explanatory diagram of an example of a functional configuration in the CPU. FIG. 7 is a flowchart showing an example of the processing operation of the transmission side ECU involved in the transmission processing. FIG. 8 is a flow chart showing an example of the processing operation of the reception side ECU related to the first reception processing. FIG. 9 is a sequence diagram showing an example of processing operation related to data communication between the transmission side ECU and the reception side ECU. FIG. 10 is a flow chart showing an example of the processing operation of the reception side ECU related to the second reception processing.

Hereinafter, embodiments of the on-vehicle system and the count updating method disclosed in the present application will be described in detail based on the drawings. The disclosed technology is not limited by the present embodiment. In addition, the embodiments described below may be combined appropriately as long as no contradiction occurs.

FIG. 1 is a block diagram showing an example of the in-vehicle system 1 of the present embodiment. An in-vehicle system 1 shown in FIG. 1 has a plurality of ECUs (Electronic Controller Units) 2 mounted on a vehicle 1 A, and each ECU 2 communicates and connects via a CAN (Controller Area Network) 3. The ECU 2 is a device that controls control of various devices in the vehicle 1A. The ECUs 2 are, for example, n ECUs # 1 to #n. For convenience of explanation, for example, the ECU 2 of # 1 is a transmitter ECU 2A that transmits a message, and the ECU 2 of #n is a receiver ECU 2B that receives a message. The transmitting side ECU 2A corresponds to a transmitting side in-vehicle device, and the receiving side ECU 2B corresponds to a receiving side in-vehicle device.

FIG. 2 is an explanatory view showing an example of a hardware configuration in the ECU 2. The ECU 2 illustrated in FIG. 2 includes a communication unit 11, a read only memory (ROM) 12, a random access memory (RAM) 13, and a central processing unit (CPU) 14. The communication unit 11 is a communication interface that manages communication with the CAN 3. The ROM 12 is an area for storing various information such as various programs. The RAM 13 is an area for storing various information. The CPU 14 controls the entire ECU 2.

When transmitting each data frame in a broadcast manner, each ECU 2 also transmits in a broadcast manner an authentication frame for verifying the authenticity of the message in the data frame. The authentication frame includes a first authentication frame 32, which is a first signal, and a second authentication frame 33, which is a second signal.

FIG. 3 is an explanatory view showing an example of the configuration of the data frame 31. As shown in FIG. A data frame 31 shown in FIG. 3 is a frame for storing data. The data frame 31 has a CAN ID 31A and data 31B that is 5 bytes long. The CAN ID 31A is an ID for identifying the content type of the CAN command. The data 31B is, for example, state information of each part in units of 1 byte. In the RAM 13, a CANID table 13A is stored that associates a CAN command with each CANID.

FIG. 4 is an explanatory view showing an example of the configuration of the first authentication frame 32. As shown in FIG. The first authentication frame 32 shown in FIG. 4 has a CAN ID 32A and an 8-byte MAC value 32B. The first authentication frame 32 is a first signal carrying a MAC value for verifying the authenticity of the MAC verification target message. The CAN ID 32A is an ID for identifying the first authentication frame 32, and is, for example, "zzzh". The 8-byte long MAC value 32B is an 8-byte long MAC value calculated by an encryption algorithm based on a MAC verification target message, a CAN ID for identifying the MAC verification target message, an internal serial number, and a common key. The internal serial number is the count value being counted by the counter unit 27. The common key corresponds to the common key used to calculate the MAC value, and is the common key stored in the key management unit 22. For convenience of explanation, the MAC value 32B is constituted by 64 bits of 8 bytes, for example, but in order to maintain security strength, it is desirable that the MAC value 32B be 64 bits or more in consideration of collision of MAC values.

FIG. 5 is an explanatory view showing an example of the configuration of the second authentication frame 33. As shown in FIG. The second authentication frame 33 shown in FIG. 5 has a CAN ID 33A, a 2-byte long serial number 33B, and a 6-byte long MAC value 33C. The second authentication frame 33 is a second signal carrying a MAC value and a serial number for verifying the authenticity of the MAC verification target message. The CAN ID 33A is an ID for identifying the second authentication frame 33, and is, for example, "yyyh". The 2-byte serial number 33 B is a count value being counted by the counter unit 27. The serial number 33B defines the delivery order of MAC verification target messages. The 6-byte MAC value 33C is the upper 6 bytes from the 8-byte MAC value calculated by the encryption algorithm based on the MAC verification target message, CANID for identifying the MAC verification target message, the internal serial number, and the common key. It is the MAC value which truncated the minute.

FIG. 6 is an explanatory view showing an example of a functional configuration in the CPU 14. The CPU 14 illustrated in FIG. 6 includes a generation unit 21, a key management unit 22, a frame communication unit 23, an analysis unit 24, a calculation unit 25, a verification unit 26, a counter unit 27, and an update unit 28. . The generation unit 21 generates frames such as the data frame 31, the first authentication frame 32, and the second authentication frame 33, for example. The key management unit 22 stores a common key used when each ECU 2 of the in-vehicle system 1 calculates the MAC value. The frame communication unit 23 is a communication unit that communicates various frames through the communication unit 11. The frame communication unit 23 transmits a frame to the CAN 3 when the transmission side ECU 2A is itself. The frame communication unit 23 receives a frame from the CAN 3 when it is the receiving ECU 2B.

The analysis unit 24 analyzes the frame content of the received frame. The analysis unit 24 refers to the CANID in the received frame to identify the frame type. The analysis unit 24 refers to the CANID in the received frame, determines that the authentication frame 32 is the first authentication frame 32 when the CANID is “zzzh”, and determines the second authentication frame 33 when the CANID is “yyyh”.

The calculation unit 25 calculates the MAC value based on, for example, the message to be transmitted, the CAN ID, the internal serial number, and the common key. The message is a message subject to MAC verification. CANID is an ID for identifying a message. The verification unit 26 compares and collates the calculated MAC value calculated by the calculation unit 25 with the received MAC value which is the MAC value in the authentication frame, and performs MAC verification based on the comparison result. If the calculation unit 25 is the transmitting ECU 2A, the calculation unit 25 calculates an 8-byte MAC value based on the MAC verification target message, the CAN ID of the MAC verification target message, the internal serial number, and the common key. When generating the first authentication frame 32, the generating unit 21 uses the CANID 32A for identifying the first authentication frame 32, and the 8-byte MAC value 32B calculated by the calculating unit 25. Generate 32 In addition, when generating the second authentication frame 33, the generation unit 21 uses the CANID 33A for identifying the second authentication frame 33, the 2-byte long internal serial number 33B, and the 6-byte long MAC value 33C. The second authentication frame 33 is generated. The 6-byte MAC value 33C is a 6-byte MAC value obtained by truncating the upper 6 bytes from the 8-byte MAC value calculated by the calculating unit 25.

If the calculation unit 25 is the receiving ECU 2B and receives the first authentication frame 32, the calculation unit 25 determines the verification target message in the data frame 31, the CAN ID of the verification target message, the internal serial number, and the common key. The calculated MAC value of 8 bytes is calculated. The message in the received data frame is a MAC verification target message that is an authentication target of the first authentication frame 32. The internal serial number is a serial number being counted by the counter unit 27 in the receiving side ECU 2B. The common key is a common key stored in the key management unit 22 in the receiving side ECU 2B. When the verification unit 26 is the receiving ECU 2 B and receives the first authentication frame 32, the calculated MAC value of 8 bytes long and the reception MAC of 8 bytes long in the first authentication frame 32. Compare and match values. If the calculated MAC value matches the received MAC value, the verification unit 26 determines that the verification result is OK, and determines that the received message is authentic. If the calculated MAC value and the received MAC value do not match, the verification unit 26 determines that the verification result is NG, and determines that the received message is not authentic.

In addition, when the calculation unit 25 is the receiving ECU 2B and receives the second authentication frame 33, the check target message in the data frame 31, the CAN ID of the check target message, the internal serial number, and the common key The MAC value of 8 bytes is calculated based on Furthermore, the calculation unit 25 truncates the MAC value for the upper 6 bytes from the MAC value for 8 bytes to obtain a calculated MAC value having a length of 6 bytes. When the verification unit 26 receives the second authentication frame 33, the verification unit 26 compares and collates the calculated MAC value of 6 byte length with the reception MAC value of 6 byte length in the second authentication frame 33. If the calculated MAC value matches the received MAC value, the verification unit 26 determines that the verification result is OK, and determines that the received message is authentic. If the calculated MAC value and the received MAC value do not match, the verification unit 26 determines that the verification result is NG, and requests the calculation unit 25 to calculate the MAC value using the serial number in the second authentication frame 33.

If the calculation unit 25 is the receiving ECU 2B and the verification result is NG, the message in the received data frame 31, the CANID of the message, the received serial number in the second authentication frame 33, and the common in the received data frame 31 are common. Based on the key, a MAC value of 8 bytes is calculated. Furthermore, the calculation unit 25 truncates the MAC value of the upper 6 bytes from the MAC value of 8 bytes to obtain a calculated MAC value. The verification unit 26 compares and collates the calculated MAC value of 6 byte length calculated using the serial number in the second authentication frame 33 with the received MAC value of 6 byte length in the second authentication frame 33. . When the calculated MAC value matches the received MAC value, the verification unit 26 determines that the verification result is OK, and determines that the received message is authentic. If the calculated MAC value and the received MAC value do not match, the verification unit 26 determines that the verification result is NG, and determines that the received message is not authentic.

The frame communication unit 23 transmits the first authentication frame 32 when transmitting the data frame 31. Furthermore, the frame communication unit 23 transmits the second authentication frame 33 instead of the first authentication frame 32 at one time every five times of the first authentication frame 32. The transmission interval of the first authentication frame is, for example, 10 ms, but the setting can be changed as appropriate.

The updating unit 28 receives the second authentication frame 33, and when the comparison result between the calculated MAC value and the received MAC value is OK, the internal number being counted by the counter unit 27 with the serial number in the second authentication frame 33. Change serial number. Furthermore, when the comparison result between the calculated MAC value calculated using the serial number in the second authentication frame 33 and the received MAC value is OK, the updating unit 28 determines the serial number in the second authentication frame 33. The counter unit 27 compares it with the internal serial number being counted. When the serial number in the second authentication frame 33 is within the allowable range, the updating unit 28 changes the internal serial number being counted to the counter unit 27 with the serial number in the second authentication frame 33. The allowable range is that the serial number in the second authentication frame 33 is larger than the internal serial number being counted by the counter unit 27, and the error between the serial numbers is within a predetermined number.

If the serial number in the second authentication frame 33 is out of the allowable range, the verification unit 26 discards the received message. If the serial number in the second authentication frame 33 is out of the allowable range, for example, the serial number in the second authentication frame 33 is smaller than the internal serial number being counted, the verification unit 26 determines that the received message is a retransmission attack. It will judge and discard the received message.

The counter unit 27 counts up the serial number at a predetermined timing. When the counter unit 27 is the transmitting ECU 2A, after transmitting the data frame 31, the counter unit 27 increments the internal serial number being counted by +1. When the counter unit 27 is the receiving ECU 2B, the counter unit 27 increments the internal serial number being counted by +1 after receiving the data frame 31.

Next, the operation of the in-vehicle system 1 of the first embodiment will be described. FIG. 7 is a flowchart showing an example of the processing operation of the transmission side ECU 2A involved in the transmission processing. The calculation unit 25 in the CPU 14 in the transmission side ECU 2A determines whether or not the message to be verified and the CANID have been acquired (step S11). When acquiring the message to be verified and the CANID (Yes at step S11), the calculation unit 25 acquires the internal serial number being counted from the counter unit 27 (step S12).

The calculation unit 25 calculates an 8-byte MAC value based on the verification target message, the CANID of the verification target message, the internal serial number, and the common key (step S13). The generation unit 21 in the CPU 14 determines whether the present time is the transmission timing of the second authentication frame 33 (step S14). The transmission timing of the second authentication frame 33 is once every five times of the first authentication frame 32.

If the current time is not the transmission timing of the second authentication frame 33 (No at Step S14), the generation unit 21 generates the first authentication frame 32 (Step S15). The generation unit 21 stores and generates the CANID for identifying the first authentication frame 32 and the 8-byte MAC value calculated in step S13.

After generating the first authentication frame 32, the frame communication unit 23 in the CPU 14 transmits the data frame 31 and the authentication frame (step S16). The counter unit 27 increments the internal serial number being counted by +1 (step S17), and ends the processing operation shown in FIG. The authentication frame is any one of the first authentication frame 32 and the second authentication frame 33.

In the case of the transmission timing of the second authentication frame 33 (Yes at step S14), the calculation unit 25 truncates the upper 6 bytes from the calculated MAC value of the 8-byte length to obtain the calculated MAC value of the 6-byte length (step S18). Furthermore, the generation unit 21 generates a second authentication frame 33 (step S19). The generation unit 21 generates a second authentication frame 33 by storing a calculated MAC value of 6 bytes long, an internal serial number of 2 bytes long, and a CAN ID for identifying the second authentication frame 33. Then, in order to transmit the data frame 31 and the authentication frame 33, the frame communication unit 23 proceeds to step S16.

The transmitting side ECU 2A transmits the first authentication frame 32 when transmitting the data frame 31, and the second authentication including the serial number instead of the first authentication frame 32 at one transmission timing every five times. Send frame 33 As a result, by periodically transmitting the second authentication frame 33 including the serial number, the amount of data communication related to the notification of the serial number can be reduced.

The second authentication frame 33 includes a MAC value of 6 bytes in length, a serial number of 2 bytes in length, and a CAN ID for identifying the second authentication frame 33. As a result, the transmitting ECU 2A can notify the receiving ECU 2B of the MAC value and the serial number.

FIG. 8 is a flowchart showing an example of the processing operation of the reception side ECU 2B related to the first reception processing. The frame communication unit 23 in the CPU 14 in the reception side ECU 2B determines whether the data frame 31 and the authentication frame are received from the CAN 3 (step S21). When the analysis unit 24 in the CPU 14 receives the data frame 31 and the authentication frame (Yes at Step S21), the analysis unit 24 acquires the CAN ID and the message from the reception data frame 31 (Step S22). The calculating unit 25 acquires the internal serial number being counted from the counter unit 27 (step S23).

The calculating unit 25 calculates an 8-byte MAC value based on the message to be authenticated, the CANID of the message to be authenticated, the internal serial number, and the common key (step S24). The verification unit 26 in the CPU 14 determines whether the received authentication frame is the first authentication frame 32 (step S25). If the received authentication frame is the first authentication frame 32 (Yes at step S25), the verification unit 26 extracts an 8-byte MAC value, that is, a received MAC value, from the first authentication frame 32 (step S26).

The verification unit 26 compares the calculated MAC value of 8-byte length calculated in step S24 with the received MAC value extracted in step S26 (step S27), and determines whether or not the verification result is OK. (Step S28). The verification unit 26 determines that the verification result is OK when the calculated MAC value and the received MAC value match.

If the verification result is OK (Step S28: Yes), the internal serial number in the count is incremented by 1 (Step S29), the received message is judged to be authentic (Step S30), and the processing operation shown in FIG. finish. When the frame communication unit 23 does not receive the data frame 31 and the authentication frame (No at step S21), the processing operation illustrated in FIG. 8 ends. If the verification result is not OK (No at Step S28), that is, if the verification result is NG, the CPU 14 determines that the received message is not authentic, discards the received message (Step S31), and ends the processing operation shown in FIG.

If the received authentication frame is not the first authentication frame 32 (No at Step S25), the calculation unit 25 determines that the received authentication frame is the second authentication frame 33. The calculation unit 25 truncates the upper 6 bytes from the calculated MAC value of the 8-byte length to calculate the calculated MAC value of the 6-byte length (step S32). The verification unit 26 extracts a reception MAC value having a length of 6 bytes from the second authentication frame 33 (step S33). The verification unit 26 compares the calculated MAC value of 6 byte length calculated in step S32 with the reception MAC value of 6 byte length extracted in step S33 (step S34), and the verification result is OK or not It is determined (step S35).

If the verification result is OK (Yes at Step S35), the CPU 14 proceeds to Step S29 in order to increment the internal serial number being counted by +1.

In the case where the verification result is not OK (No at Step S35), the calculation unit 25 calculates a MAC value of 6 bytes in length based on the CAN ID in the reception data frame 31, the message, the reception serial number in the second authentication frame 33, and the common key. Is calculated (step S36). The verification unit 26 compares the received MAC value of 6 byte length extracted in step S33 with the calculated MAC value of 6 byte length calculated in step S36 (step S37), and determines whether the verification result is OK or not. Is determined (step S38).

If the verification result is OK (Yes at Step S38), the updating unit 28 in the CPU 14 determines whether the reception serial number in the second authentication frame 33 is within the allowable range (Step S39). The updating unit 28 compares the received serial number in the second authentication frame 33 with the internal serial number being counted by the counter unit 27. If the received serial number in the second authentication frame 33 is larger than the internal serial number and the difference between the received serial number and the internal serial number is within a predetermined number, the verification unit 26 determines that the received message is genuine. to decide.

When the reception serial number is within the allowable range (Yes at step S39), the update unit 28 changes the internal serial number being counted by the counter unit 27 to the reception serial number in the second authentication frame 33 (step S40). . Then, the verification unit 26 proceeds to step S30 to determine that the received message is authentic.

If the verification result is not OK (No at Step S38), the verification unit 26 discards the received message (Step S41), and ends the processing operation illustrated in FIG. If the received serial number is not within the allowable range (No at Step S39), the verification unit 26 proceeds to Step S41 to discard the received message.

When the received authentication frame is the first authentication frame 32, the receiving ECU 2B calculates an 8-byte MAC value based on the message in the data frame 31, the CAN ID, the internal serial number, and the common key. Furthermore, the receiving ECU 2B compares and compares the calculated MAC value of 8-byte length with the received MAC value of 8-byte length in the first authentication frame 32, and when the calculated MAC value matches the received MAC value. Judge that the received message is genuine. As a result, the receiving ECU 2B can determine the authenticity of the received message.

The reception side ECU 2 B compares and collates the calculated MAC value of 8-byte length with the received MAC value of 8-byte length in the first authentication frame 32, and when the calculated MAC value and the received MAC value do not match, the received message It is determined that is not authentic. As a result, the receiving ECU 2B can determine the authenticity of the received message.

When the received authentication frame is the second authentication frame 33, the receiving ECU 2B calculates an 8-byte MAC value based on the message in the received data frame, the CAN ID, the internal serial number, and the common key. The reception-side ECU 2B truncates the upper 6 bytes from the 8-byte MAC value to obtain a calculated MAC value of 6 bytes. The reception side ECU 2 B compares and collates the calculated MAC value of 6 byte length with the received MAC value of 6 byte length in the second authentication frame 33, and when the calculated MAC value and the received MAC value match, reception serial It is determined whether the number is within the allowable range. When the reception serial number is in the allowable range, the reception ECU 2B determines that the reception message is authentic. As a result, the receiving ECU 2B can determine the authenticity of the received message.

Furthermore, when the received serial number is within the allowable range, the receiving ECU 2B changes the internal serial number being counted to the received serial number in the second authentication frame 33. As a result, for example, even if a message is missing and a serial number mismatch occurs between the transmitting side ECU 2A and the receiving side ECU 2B, the internal serial number being counted is aligned and the transmitting side ECU 2A and the receiving side ECU 2B You can establish synchronization between serial numbers.

When the calculated MAC value of 6-byte length and the received MAC value of 6-byte length do not match, the receiving ECU 2B determines that the received message is not authentic. As a result, the receiving ECU 2B can determine the authenticity of the received message.

FIG. 9 is a sequence diagram showing an example of processing operation related to data communication between the transmission side ECU 2A and the reception side ECU 2B. The transmission side ECU 2A shown in FIG. 9 calculates a MAC value from the message to be verified, the CANID to be verified, the common key, and the internal serial number "1" (step S51). The transmitting side ECU 2A notifies the receiving side ECU 2B of the data frame 31 (step S52). Furthermore, the transmitting side ECU 2A notifies the receiving side ECU 2B of the second authentication frame 33 storing the MAC value and the internal serial number "1" (step S53). Then, the transmitting side ECU 2A increments the internal serial number “1” being counted by +1 to make the internal serial number “2” (step S54).

The reception side ECU 2B calculates the MAC value based on the message to be verified in the data frame 31, the CAN ID to be verified, the common key, and the internal serial number "1". Further, the receiving ECU 2B compares the calculated MAC value with the received MAC value in the second authentication frame 33, and sets the verification result as OK (step S55). The receiving ECU 2B increments the internal serial number “1” being counted by +1 to obtain an internal serial number “2” (step S56).

Furthermore, the transmitting side ECU 2A calculates the MAC value based on the message to be verified, the CANID to be verified, the common key, and the internal serial number "2" (step S57). The transmitting side ECU 2A notifies the receiving side ECU 2B of the data frame 31 (step S58). Furthermore, the transmission side ECU 2A notifies the reception side ECU 2B of the first authentication frame 32 storing the MAC value (step S59). Then, the transmitting side ECU 2A increments the internal serial number "2" being counted by +1 to make the internal serial number "3" (step S60).

The reception side ECU 2B calculates the MAC value based on the message to be verified in the data frame 31, the CAN ID to be verified, the common key, and the internal serial number "2". Furthermore, the receiving ECU 2B compares the calculated MAC value with the received MAC value in the first authentication frame 32, and sets the verification result as OK (step S61). The reception side ECU 2B increments the serial number “1” being counted by +1 to make the serial number “2” (step S62).

Thereafter, when the serial number being counted is “5”, the transmitting side ECU 2A calculates the MAC value based on the message to be verified, the CANID to be verified, the common key and the internal serial number “5” (step S63). . The transmitting side ECU 2A notifies the receiving side ECU 2B of the data frame 31 (step S64). Furthermore, the transmission side ECU 2A notifies the reception side ECU 2B of the first authentication frame 32 storing the MAC value (step S65). Then, the transmitting side ECU 2A increments the internal serial number "5" being counted by +1 to make the internal serial number "6" (step S66).

However, it is assumed that, for example, the receiving side ECU 2B causes a message loss that the data frame 31 and the first authentication frame 32 can not be received from the transmitting side ECU 2A due to some failure.

Then, the transmitting side ECU 2A calculates the MAC value based on the message to be verified, the CANID to be verified, the common key, and the internal serial number "6" (step S67). The transmission side ECU 2A notifies the reception ECU 2B of the data frame (step S68). Furthermore, the transmitting side ECU 2A notifies the receiving side ECU 2B of the second authentication frame 33 storing the MAC value and the internal serial number "6" (step S69). Then, the transmitting side ECU 2A increments the internal serial number "6" being counted by +1 to make the internal serial number "7" (step S70).

At this time, the reception side ECU 2B calculates the MAC value based on the message in the data frame 31, the CAN ID, the common key, and the internal serial number "5". As a result, since the reception side ECU 2B could not receive the data frame 31 of step S64 and the first authentication frame 32 of step S65, the internal serial number being counted remains "6". Therefore, when the reception side ECU 2B compares the calculated MAC value with the received MAC value in the second authentication frame 33, the verification result becomes NG (step S71).

However, the receiving ECU 2 B calculates the calculated MAC value based on the CAN ID in the data frame 31, the message, the common key, and the serial number “6” in the second authentication frame 33. Then, the reception side ECU 2B compares the calculated MAC value with the received MAC value in the second authentication frame 33, and the verification result is OK (step S72). The receiving ECU 2 B changes the internal serial number “5” being counted to the serial number “6” in the second authentication frame 33. As a result, the reception side ECU 2B can establish synchronization of serial numbers with the transmission side ECU 2A. Then, the reception side ECU 2B increments the internal serial number "6" being counted by +1 to make the internal serial number "7" (step S73).

The transmitting side ECU 2A transmits the first authentication frame 32 when transmitting the data frame 31, and the second authentication including the serial number instead of the first authentication frame 32 at a predetermined timing once in five times. Send frame 33 As a result, by periodically transmitting the second authentication frame 33 including the serial number, it is possible to reduce the amount of data communication related to the notification of the serial number between the transmitting ECU 2A and the receiving ECU 2B.

The transmitting side ECU 2A notifies the receiving side ECU 2B at a predetermined timing of the second authentication frame 33 including the MAC value of 6 byte length, the serial number of 2 byte length, and the CAN ID for identifying the second authentication frame 33. . As a result, since the transmission side ECU 2A notifies the second authentication frame 33 at a predetermined timing, it can notify the MAC value and the serial number while reducing the amount of data communication. Furthermore, the reception side ECU 2B can identify the second authentication frame 33 by referring to the CAN ID in the reception frame.

If the received authentication frame is the first authentication frame 32, the receiving ECU 2B calculates an 8-byte MAC value based on the verification target message in the received data frame 31, CAN ID, internal serial number, and common key. . Furthermore, the receiving ECU 2B compares and compares the calculated MAC value of 8-byte length with the received MAC value of 8-byte length in the first authentication frame 32, and when the calculated MAC value matches the received MAC value. Judge that the received message is authentic. As a result, the receiving ECU 2B can determine the authenticity of the received message.

When the received authentication frame is the second authentication frame 33, the receiving ECU 2B calculates an 8-byte MAC value based on the verification target message in the received data frame 31, CAN ID, internal serial number, and common key. . The reception-side ECU 2B truncates the upper 6 bytes from the 8-byte MAC value to obtain a calculated MAC value of 6 bytes. The reception side ECU 2 B compares and collates the calculated MAC value of 6 byte length with the received MAC value of 6 byte length in the second authentication frame 33, and when the calculated MAC value and the received MAC value match, reception serial It is determined whether the number is within the allowable range. When the reception serial number is within the allowable range, the reception side ECU 2B determines that the reception message is authentic. As a result, the receiving ECU 2B can determine the authenticity of the received message.

Note that the receiving side ECU 2B according to the first embodiment compares the received MAC value in the second authentication frame 33 with the received MAC value using the received serial number in the second authentication frame 33, and confirms the verification result OK. In the case of, the received message was judged as genuine without changing the internal serial number. However, the present invention is not limited to this, and an embodiment thereof will be described below as Example 2. The same components as those of the in-vehicle system 1 of the first embodiment are denoted by the same reference numerals, and the description of the same components and operations will be omitted.

When receiving the second authentication frame 33, the receiving side ECU 2B calculates using the 6-byte length reception MAC value in the second authentication frame 33 and the reception serial number in the second authentication frame 33. The calculated MAC value of the 6-byte length is compared and collated. Furthermore, when the received MAC value matches the calculated MAC value, the receiving ECU 2 B changes the internal serial number being counted to the received serial number in the second authentication frame 33.

Next, the operation of the in-vehicle system 1 of the second embodiment will be described. FIG. 10 is a flowchart showing an example of the processing operation of the reception side ECU 2B related to the second reception processing. The updating unit 28 determines whether the verification result is OK (step S35A). If the verification result is OK (Yes at Step S35A), the updating unit 28 changes the internal serial number being counted to the reception serial number in the second authentication frame 33 (Step S40A). After changing the internal serial number to the reception serial number in the second verification frame 33, the verification unit 26 proceeds to step S30 in order to determine that the received message is authentic. If the verification result is not OK (No at Step S35), the updating unit 28 proceeds to Step S36 in order to calculate a MAC value having a length of 6 bytes.

The receiving ECU 2 B changes the internal serial number being counted to the receiving serial number in the second authentication frame 33. As a result, when receiving the second authentication frame 33, the receiving ECU 2B can synchronize the serial number with the transmitting ECU 2A.

The receiving ECU 2B determines whether the received frame is the first authentication frame 32 or the second authentication frame 33 based on the CANID in the received frame. Therefore, different CANIDs are included in the first authentication frame 32 and the second authentication frame 33. However, if there is no CAN ID, it may be determined whether or not there is a serial number in the received frame, and if there is a serial number, it may be determined that the received frame is the second authentication frame.

Further, each component of each unit shown in the drawings does not necessarily have to be physically configured as shown in the drawings. That is, the specific form of the dispersion and integration of each part is not limited to the illustrated one, and all or a part thereof is functionally or physically dispersed or integrated in any unit according to various loads, usage conditions, etc. Can be configured.

Furthermore, various processing functions performed by each device are performed by executing all or any part thereof on a CPU (or a microcomputer such as a micro processing unit (MPU) or a micro controller unit (MCU)). Also good. In addition, various processing functions may execute all or any part of them on a program analyzed and executed by a CPU (or a microcomputer such as an MPU or an MCU) or on hardware by wired logic. Needless to say.

1 in-vehicle system 1A vehicle 2A transmitter ECU
2B Receiver ECU
21 generation unit 22 key management unit 23 frame communication unit 24 analysis unit 25 calculation unit 26 verification unit 27 counter unit 28 update unit

Claims

The same internal count value is held between the transmitting on-vehicle apparatus and the receiving-side on-vehicle apparatus in the vehicle, and the receiving on-vehicle apparatus delivers the order of delivery of data received from the transmitting on-vehicle apparatus based on the internal count value. An in-vehicle system that defines
The transmitting on-vehicle apparatus
A first signal including an authentication value for identifying the authenticity of data to be transmitted, and a communication unit that selectively transmits a second signal including a count value in addition to the authentication value;
The receiving side in-vehicle device is
An analysis unit that determines whether the received signal includes the count value;
And an updating unit configured to update the internal count value held by the device based on the received count value when the received signal includes the count value.
The transmitting on-vehicle apparatus
A calculation unit that calculates the authentication value based on the data to be transmitted, a predetermined common key, and an internal count value held by the apparatus itself;
A generation unit that adds the authentication value to the first signal or the second signal;
The receiving side in-vehicle device is
A calculation unit that calculates a first authentication value based on the data received from the transmission-side in-vehicle apparatus, the predetermined common key, and the internal count value held by the own apparatus;
A verification unit that collates the authentication value extracted from the signal received from the transmission side in-vehicle device with the first authentication value, and verifies the authenticity of the received data based on the first collation result; The on-vehicle system according to claim 1, comprising:
The updating unit is
The internal count value held by the own device is updated with the count value in the received second signal when it is determined that the data is authentic based on the first collation result. The in-vehicle system according to claim 2.
The calculation unit in the reception side in-vehicle apparatus is
If it is determined that the received data is not authentic based on the first comparison result, the count value in the second signal, the data received from the transmitting on-vehicle apparatus, and the predetermined common key Calculate a second authentication value based on
The verification unit
Verifying the authentication value extracted from the second signal received from the transmission-side in-vehicle apparatus with the second authentication value, and verifying the authenticity of the received data based on the second comparison result. The vehicle-mounted system of Claim 2 or 3 characterized by the above-mentioned.
The updating unit is
The internal count value held by the own device is updated with the count value in the second signal when it is determined that the received data is authentic based on the second comparison result. The in-vehicle system according to claim 4.
The same internal count value is held between the transmitting on-vehicle apparatus and the receiving-side on-vehicle apparatus in the vehicle, and the receiving on-vehicle apparatus delivers the order of delivery of data received from the transmitting on-vehicle apparatus based on the internal count value. Method for updating the count value in an on-vehicle system that defines
The transmitting on-vehicle apparatus
Selectively transmitting a first signal including an authentication value identifying authenticity of data to be transmitted, and a second signal including a count value in addition to the authentication value;
The receiving side in-vehicle device is
Determining whether the received signal includes the count value;
And updating the internal count value held by the apparatus based on the received count value when the received signal includes the count value.