JP6454614B2 - In-vehicle system, control device and control method thereof - Google Patents

Description

  The present invention relates to an in-vehicle system, a control device thereof, and a control method.

  In an in-vehicle system that supports control of an automobile, an embedded system called an ECU (Electronic Control Unit) performs control as a control device. For example, in the case of engine control, the ECU observes the state of the engine or the like with a sensor, calculates the fuel injection amount, and performs control for ignition at an appropriate timing. Furthermore, the control processing is a periodic operation and the execution cycle is short. Therefore, the data update frequency is high.

  Controller Area Network (hereinafter referred to as CAN) is widely used as a typical standard protocol for in-vehicle networks of automobiles, and in the future, CAN FD (Flexible Data-Rate), which is an extension of CAN, is expected to spread. Yes.

  As with general information systems, threats are also being pointed out for in-vehicle systems using such in-vehicle networks. For example, there is a threat that a replay attack (retransmission attack) is performed by connecting an unauthorized device to an interface directly connected to an in-vehicle network such as an OBD2 (On-Board-Diagnostics 2) port. Here, the replay attack is an attack in which an attacker eavesdrops on a packet flowing on a communication path, acquires the packet in advance, and resends the acquired packet to cause an illegal operation of the automobile.

  As a countermeasure against a replay attack on a recipient's system by a third party, it is known to assign a sequence number (order number) whose value changes for each packet. The replay attack countermeasure technique based on sequence numbers is also adopted in IPSec standardized by IETF as a protocol for performing authentication and encryption at the network layer.

  Also, it is known to generate a random number whose value changes for each packet and to employ it as a sequence number in order to ensure the difficulty of prediction. Then, the bitwise exclusive OR of the output Xi of the pseudo random number generator and the output Xi-m of the pseudo random number generator before m steps obtained from the m delay unit B is taken, and then the arithmetic unit C A technique for creating a ciphertext by taking a bitwise exclusive OR of the result of the exclusive OR and the plaintext block Mi is disclosed.

JP 2003-158515 A

  According to the technology disclosed in Patent Document 1, in a system that encrypts a long sentence composed of a plurality of blocks with a pseudo-random number generator, a long sentence with the same processing amount and safety level as that of encrypting a single block. Each block can be encrypted efficiently.

  However, a control device in an in-vehicle system is often required to be low-cost, and the computational resources that can be used for cryptographic processing are limited. Therefore, the technology disclosed in Patent Document 1 is also burdensome and the computational resources are exhausted. May affect vehicle control. Further, in a vehicle-mounted system, one control device often transmits control information to a plurality of other control devices, and generating an independent random number sequence for each of a plurality of control devices as transmission destinations is a heavy burden.

  Accordingly, an object of the present invention is to provide random number processing suitable for vehicle system communication.

  A representative control device according to the present invention is a control device that transmits control information in an in-vehicle system, and a mask value associated with each of a random number storage unit that stores a plurality of base random numbers and a plurality of identifiers of a packet. Is stored, and one base random number is obtained from a plurality of base random numbers stored in the random number storage unit, and from among a plurality of mask values stored in the mask value storage unit, A packet random number generating unit that acquires a mask value associated with an identifier of a packet for transmitting the control information, generates a packet random number based on the acquired base random number and the acquired mask value, the control information, and the control information And a communication unit that transmits a packet including the generated packet random number.

  According to the present invention, random number processing suitable for vehicle system communication can be performed.

It is a figure which shows the example of a structure of a vehicle-mounted system. It is a figure which shows the example of a hardware structure of a control apparatus. It is a figure which shows the example of the whole flow of communication. It is a figure which shows the example of the flow of a confidential sharing process. It is a figure which shows the example of the flow of a packet transmission process. It is a figure which shows the example of the flow of a packet reception process. It is a figure which shows the example of a structure of a mask value table. It is a figure which shows the example of a structure of a communication packet. It is a figure which shows the example of a structure of the vehicle-mounted system containing a some reception control apparatus. It is a figure which shows the example of a structure of the vehicle-mounted system containing synchronous correction | amendment. It is a figure which shows the example of the whole flow of communication containing a synchronous correction | amendment. It is a figure which shows the example of the flow of a synchronous correction process of a transmission control apparatus. It is a figure which shows the example of the flow of a synchronous correction process of a reception control apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings using examples.

(In-vehicle system configuration)
With reference to FIG. 1, the example of a structure of a vehicle-mounted system is demonstrated. In FIG. 1, the in-vehicle system 100 includes a transmission control device 110, a reception control device 130, and a communication bus 190. In the in-vehicle system 100, the transmission control device 110 generates a packet random number and transmits a packet storing the packet random number together with data via the communication bus 190. The reception control device 130 verifies the authenticity of the random number of the received packet, and acquires data stored in the received packet whose authenticity has been verified.

  Hereinafter, transmission and reception of the transmission control device 110 and the reception control device 130 may be simply referred to as a control device without being distinguished. In addition, each of the transmission control device 110 and the reception control device 130 may be a control device having both transmission and reception configurations.

(Transmission control device)
One or more control devices are connected to the communication bus 190. Here, an example is shown in which two control devices, the transmission control device 110 and the reception control device 130, are connected. The transmission control device 110 includes a communication unit 111, a communication packet generation unit 112, a packet random number generation unit 113, a mask value table generation unit 114, a base random number generation unit 115, a key management unit 117, a base random number storage unit 118, and a mask value table storage. A portion 119 is included.

  The communication unit 111 transmits the communication packet generated by the communication packet generation unit 112 to the reception control device 130 via the communication bus 190. The communication packet generator 112 generates a communication packet. The packet random number generator 113 generates a packet random number. The mask value table generation unit 114 generates a mask value table. The base random number generator 115 generates a base random number.

  The key management unit 117 manages keys used when the packet random number generation unit 113 and the base random number generation unit 115 perform encryption processing for generating respective random number data. The base random number storage unit 118 stores the base random number generated by the base random number generation unit 115. The mask value table storage unit 119 stores a table of mask values generated by the mask value table generation unit 114.

(Reception control device)
The reception control device 130 includes a communication unit 131, a communication packet verification unit 132, a packet random number generation unit 133, a base random number generation unit 135, a key management unit 137, a base random number storage unit 138, and a mask value table storage unit 139. ing. Note that the base random number generation unit 135 may not be included. The communication unit 131 receives the communication packet generated by the communication packet generation unit 112 of the control device 110 via the communication bus 190. The communication packet verification unit 132 verifies the packet random number included in the communication packet transmitted from the control device 110.

  The packet random number generation unit 133 performs processing with the mask value table and the base random number as inputs in order for the communication packet verification unit 132 to verify the communication packet, and generates a packet random number. The base random number generator 135 generates a base random number by cryptographic processing. The key management unit 137 manages keys used when the packet random number generation unit 133 and the base random number generation unit 135 perform encryption processing for generating respective data. The base random number storage unit 138 stores a base random number.

  The mask value table storage unit 139 stores a mask value table used as an input by the packet random number generation unit 133 to generate a packet random number. The stored mask value table may be received by the mask value table generating unit 134 of the transmission control device 110 or may be generated by the reception control device 130 itself. The communication packet verification unit 132 verifies the packet random number stored in the packet received from the transmission control device 110, and the data of the packet determined to be normal is stored in the reception control device 130.

(Hardware configuration of control device)
An example of the hardware configuration of the control device will be described with reference to FIG. In this example, the hardware of the transmission control device 110 and the reception control device 130 is the same, and will be described collectively. In FIG. 2, the control device includes a communication device 11, an input / output device 12, a CPU (Central Processing Unit) 14, and a memory 15.

  The CPU 14 reads information from the communication device 11, the input / output device 12, and the memory 15 according to the program stored in the memory 15, performs an operation on the read information, and sends the information to the communication device 11, the input / output device 12, and the memory 15. Write. The memory 15 stores a program of the CPU 14 or temporarily stores a processing result of the CPU 14. The input / output device 12 communicates with a sensor or an actuator (not shown) of the vehicle. The communication device 11 communicates with other control devices via the communication bus 190.

  When the CPU 14 executes a program stored in the memory 15, the CPU 14 and the memory 15 may be each unit such as the communication packet generation unit 112 illustrated in FIG. 1. The communication units 111 and 131 may include the communication device 11. The base random number storage units 118 and 138 and the mask value table storage units 119 and 139 may be the memory 15. 1 may be formed including hardware other than the CPU 14, the memory 15, and the communication device 11 that are not shown.

  The CPU 14 and the memory 15 may be low cost. For this reason, for example, the CPU 14 may not have high performance, and the memory 15 may not have a large capacity.

(Overall overview of communication processing between transmission control device and reception control device)
With reference to FIG. 3, an example of an overall outline of communication processing between the transmission control device 110 and the reception control device 130 will be described. The transmission control device 110 stores a packet random number, which is a substitute for the sequence number of the communication packet, in the communication packet. The packet random number is generated using a mask value table which is a table storing data of each packet ID and a mask value secretly and randomly selected corresponding to the packet ID. Here, the secret means a value stored only in the control device 110 and the control device 130.

  An example of the mask value table will be described later with reference to FIG. A base random number is generated cryptographically by using a pseudo-random number generator included in an encryption process (for example, AES: Advanced Encryption Standard), and the transmission control device 110 and the reception control device 130 generate the base random number and the mask value table. It is characterized by sharing and generating packet random numbers using them.

  The transmission control device 110 and the reception control device 130 divide the phases when the engine of the vehicle is activated and when it is actually used, and perform processing according to each phase. First, when the engine is started, a secret sharing process (S201) is performed between the transmission control device 110 and the reception control device. In actual use, the transmission control device 110 repeats the packet random number transmission processing (S202), and in response to this, the reception control device 130 repeats the packet random number reception processing (S203). carry out.

  The secret sharing process (S201) such as when the engine is started includes a base random number sharing process (S311) and a mask value table sharing process (S312), and pre-shares the base random number and the mask value table. Details of the base random number sharing process (S311) and the mask value table sharing process (S312) will be described with reference to FIG.

  In actual use, the transmission control device 110 refers to the mask value table (S315), generates a packet random number (S316), and transmits the packet random number (S202). The reception control device 130 refers to the mask value table (S324), generates a packet random number (S326), and verifies the packet (S326). The packet random number transmission process (S202) and the packet random number reception process (S203) will be further described later with reference to FIGS.

(Confidential sharing processing)
FIG. 4 is a diagram illustrating an example of the secret sharing process (S201) when the engine is activated. As already described, the secret sharing process (S201) includes a base random number sharing process (S311) and a mask value table sharing process (S312).

  First, the base random number sharing process (S311) will be described. The reception control device 130 transmits parameters such as a random number generation amount (number of random numbers) necessary for base random number generation to the transmission control device 110 (S421). The base random number generation unit 115 of the transmission control device 110 receives parameters from the reception control device 130 (S410), and determines parameters necessary for generating base random numbers (S411). Here, the parameter to be determined may be, for example, a parameter according to the random number generation amount.

  Based on the determined parameters, the base random number generation unit 115 generates a base random number and stores it in the base random number storage unit 118 (S412). Note that the base random number generation unit 115 generates a base random number by using pseudo random number generation used in the encryption process in which the key information stored in the key management unit 117 is input.

  Here, a plurality of base random numbers may be generated and may be pseudorandom numbers of a predetermined series. The length (bit length) of one base random number may be sufficiently long, and the number corresponding to the determined parameter may be generated. The generated base random number is transmitted to the reception control device 130 (S413), and the reception control device 130 receives the transmitted base random number (S422).

  Next, the mask value table sharing process (S312) will be described. The mask value table generation unit 114 of the transmission control device 110 generates a mask value, which is data depending on the packet ID, for each packet ID (S414), and uses the packet ID as an index and a value corresponding to this index as a mask value. A mask value table to be generated is generated and stored in the mask value table storage unit 119 (S415).

  The generated mask value table is transmitted to the reception control device 130 (S416), and the reception control device 140 receives the transmitted mask value table (S423), and if the mask value table has not been set up to the reception time point. The received mask value table is stored in the mask value table storage unit 139. Otherwise, the mask value table storage unit 139 is updated with the received mask value table (S424).

  Note that the mask value itself may be generated by a pseudo-random number generator or the like used for encryption processing as long as it is data that depends on the packet ID. The mask value table update (S424) is performed when the engine is started, and the same mask value table is continuously used during the actual vehicle use period. The generation of the base random number and the generation of the mask value table may be performed by both the transmission control device 110 and the reception control device 130.

(Transmission control device packet random number transmission)
An example of packet random number transmission processing (S202) will be described with reference to FIG. In this example, a plurality of base random numbers are stored in the base random number storage unit 118, and each base random number is indicated by an index. Each base random number may be fixed-length data. First, a base random number index, which is an index indicating a location where a base random number is used, in the base random number storage unit 118 is initialized.

  The transmission control apparatus 110 acquires a base random number corresponding to the length of the packet random number from the location indicated by the base random number index in the base random number storage unit 118, and sets the value of the base random number index to the length of one base random number. Increment by (S501). The ID of the packet to be transmitted is acquired (S502), the mask value table stored in the mask value table storage unit 119 is referred to (S503), and the mask value corresponding to the acquired packet ID is acquired (S504).

  The packet random number generation unit 115 generates a packet random number from the exclusive OR of the acquired base random number and the acquired mask value (S505). The communication packet generator 112 adds the generated packet random number to data acquired from a control application (not shown) that runs on the transmission control device 110, and generates a communication packet (S506). The communication unit 111 transmits the communication packet generated by the communication packet generation unit 112 to the reception control device 130 via the bus 190 (S507). And it returns to acquisition of a base random number (S501).

  The configuration of the communication packet will be described later with reference to FIG. The increment of the value of the base random number index may be at a predetermined timing including when the base random number is acquired and when the base random number is not acquired. The predetermined timing may be a preset time interval, for example, every 10 mS, or may be a preset time interval, for example, every 10 mS starting from 0: 0: 0. Further, with respect to one acquisition of the base random number (S501), a plurality of processes from the acquisition of the packet ID (S502) to the transmission of the communication packet (S507) may be executed within a preset period.

(Receive control device packet random number reception)
The packet random number reception process (S203) will be described with reference to FIG. The base random number index, which is an index indicating the location where the base random number is used, in the base random number storage unit 138 is initialized. The reception control device 130 acquires a base random number corresponding to the length of the packet random number from the location indicated by the base random number index in the base random number storage unit 138, and increments the value of the base random number index by the length of the random number. (S601).

  The communication unit 131 receives a communication packet via the communication bus 190 (S602), acquires a packet random number, and acquires a packet ID (S603). The mask value table stored in the mask value table storage unit 139 is referred to (S604), and the mask value corresponding to the acquired packet ID is acquired (S605). The packet random number generation unit 132 generates a packet random number from the exclusive OR of the acquired base random number and the acquired mask value (S606).

  The communication packet verifying unit 132 verifies whether the packet random number acquired from the communication packet is equal to the generated packet random number, verifies the communication packet (S607), and determines that the two packet random numbers are equal (S608). ), Assuming that the communication packet is authentic, the communication packet data is stored in a storage unit (not shown) (S609). When it is determined that the two packet random numbers are not equal (S608), the communication packet verification unit 132 discards the received communication packet. And it returns to acquisition of a base random number (S601).

  The increment of the value of the base random number index may be at a predetermined timing including when the base random number is acquired and when the base random number is not acquired. The predetermined timing may be a preset time interval, for example, every 10 mS, or may be a preset time interval, for example, every 10 mS starting from 0: 0: 0. It may be based on a signal from the transmission control device 110. For this reason, a plurality of processes from packet reception (S602) to packet data storage (S609) may be executed for one base random number acquisition (S601).

  Next, in order to indicate what kind of configuration information is processed or communicated between the transmission control device 110 and the reception control device 130, various types of information can be shown. The structure of will be described.

(Configuration of mask value table)
An example of the configuration of the mask value table 900 will be described with reference to FIG. The mask value table 900 is generated by the mask value table generation unit 114 and stored in the mask value table storage units 119 and 139. The mask value table 900 includes a packet ID column 901 and a mask value column 902. In this example, “ID_1” in the packet ID column 901 and “MASK_ID1” in the mask value column 902 correspond to each other. Hereinafter, “ID_2” and “ID_3” in the packet ID column 901 of the mask value table 900 are tables associated with “MASK_ID2” and “MASK_ID3” in the mask value column 902, respectively.

  Each mask value in the mask value column 902 is generated by the mask value table generation unit 114 by generating pseudo-random numbers for cryptographic processing using the key information stored in the key management unit 117 and the packet ID in the packet ID column 901 as inputs. Also good. The mask value in the mask value column 902 depends on the packet ID by using a random number using the packet ID in the packet ID column 901. Note that generation of the mask value is not limited to such processing. Further, the configuration of the mask value table 900 is not limited to the example shown in FIG.

(Composition of communication packet)
An example of the configuration of the communication packet 1000 will be described with reference to FIG. The communication packet 1000 is a communication packet generated by the communication packet generation unit 112. For example, the communication packet 1000 is transmitted from the communication unit 111 to the communication bus 190 in the packet transmission (S317) described with reference to FIG. ) Is a communication packet received by the communication unit 131.

  The communication packet 1000 includes header information 1011, data 1012, packet random numbers 1013, and footer information 1015. The header information 1011 indicates, for example, an arbitration field and a control field in the CAN FD of the communication bus 190 that is an in-vehicle network. In other communication protocols, the header information 1011 may include information indicating a communication destination, a communication source, a data length, and the like. That's fine. The header information may include a packet ID.

  The data 1012 is data for controlling the vehicle, and is used if the reception control device 130 determines that the data is authentic. The packet random number 1013 is the packet random number already described which is generated by the packet random number generation units 113 and 133, and may be a random number having a certain length. The packet random number 1013 may be regarded as verification information. The footer information 1014 indicates, for example, a periodic redundancy check field and an acknowledge field in the CAN FD of the communication bus 190 that is an in-vehicle network.

  The information constituting the communication packet 1000 is not limited to the example of FIG. 8, the order of information is not limited to the example of FIG. 8, and the contents of each information are the same as described with reference to FIG. It is not limited.

  As described above, a different random number sequence can be generated for each packet ID by a simple operation called exclusive OR.

(Packet random number transmission to multiple reception control devices)
An example of packet random number transmission processing to a plurality of reception control apparatuses 130 will be described with reference to FIG. FIG. 9 illustrates an example in which a single transmission control apparatus 110 transmits a communication packet 1104 with a packet ID “ID_1” to the reception control apparatus 130 and transmits a communication packet 1105 with a packet ID “ID_2” to the reception control apparatus 140. FIG.

  The transmission control device 110 transmits a packet from the location specified by the base random number index in the base random number storage unit 118 to transmit the communication packet 1104 and the communication packet 1105 to the reception control device 130 and the reception control device 140, respectively. The value “IV_ID1” of the base random number 1101-1 having the same length as the random number is acquired. Also, referring to the mask value table storage unit 119, the value “MASK_ID1” of the mask value 1102-1 corresponding to the packet ID “ID_1” and the value “mask1” of the mask value 1103-1 corresponding to the packet ID “ID_2” “ MASK_ID2 "is acquired.

  Next, the value “IV_ID1” and the value “MASK_ID1” are exclusive-ORed to calculate a random number “r1”, and a communication packet 1104 including the packet ID “ID_1” and the random number “r1” is generated. To 130. Also, the value “IV_ID2” and the value “MASK_ID2” are exclusive-ORed to calculate a random number “r2” to generate a communication packet 1105 including the packet ID “ID_2” and the random number “r2”. Send to.

  The reception control device 130 acquires a random number “r1” from the received communication packet 1104. The value “IV_ID1” of the base random number 1101-2 having the same length as the packet random number is acquired from the location specified by the base random number index in the base random number storage unit 138, and the mask value table storage unit 139 is referred to. The value “MASK_ID1” of the mask value 1102-2 corresponding to the ID “ID1” is acquired.

  Next, the value “IV_ID1” and the value “MASK_ID1” are exclusive-ORed to calculate a random number “r1”, which is compared with the random number “r1” acquired from the communication packet 1104. In this example, since the values of the base random number 1101-1 and the base random number 1101-2 are equal to “IV_ID1” and the values of the mask value 1102-1 and the mask value 1102-2 are equal to “MASK_ID1”, the random number “r1” is also It is determined that the comparison results are equal. If it is determined that they are equal to each other, the communication packet 1104 is verified to be authentic.

  The reception control device 140 acquires a random number “r2” from the received communication packet 1105. The value “IV_ID1” of the base random number 1101-3 having the same length as the packet random number is acquired from the location specified by the base random number index in the base random number storage unit 148, and the packet ID is “ The value “MASK_ID2” of the mask value 1103-3 corresponding to “ID2” is acquired.

  Next, the value “IV_ID1” and the value “MASK_ID2” are exclusive-ORed to calculate a random number “r2”, which is compared with the random number “r2” acquired from the communication packet 1104. In this example, since the values of the base random number 1101-1 and the base random number 1101-3 are equal to “IV_ID1” and the values of the mask value 1103-1 and the mask value 1103-3 are equal to “MASK_ID2”, the random number “r2” is also It is determined that the comparison results are equal. If it is determined that the communication packets 1105 are equal to each other, the communication packet 1105 is verified to be authentic.

  Note that the data included in the packet 1104 and the packet 1105 may be the same or different.

  As described above, even when a packet is transmitted from a single transmission control device to a plurality of different reception control devices, a simple exclusive OR operation is performed for each packet ID used for each of a plurality of different reception control devices. Random numbers can be generated by simple operations. For this reason, even if it is a low-cost control apparatus like a vehicle-mounted system, the security of a vehicle-mounted system can be ensured, without having a bad influence on vehicle control.

  In particular, in a system in which control information is often transmitted in the same cycle, for example, at an interval of 10 mS, such as an in-vehicle system, a large amount of common base random numbers can be used, so the degree of saving of calculation resources of the control device is high. .

  In addition, it is preferable to apply to a system in which many packets are transmitted in the same cycle because the degree of saving of calculation resources for generating random numbers is high.

  Since the base random number of one series is 1 MB, for example, if base random numbers of a plurality of series are stored and periodically updated to improve security, the in-vehicle system has a high update cost. Since the random number storage units 118, 138, and 148 store only one series of base random numbers, the update cost of the base random numbers can be reduced. Further, since the storage capacity of the base random number storage units 118, 138, and 148 is reduced, a small-capacity memory 15 can be employed.

(Communication protection system that performs synchronization correction)
In the configuration described in the first embodiment, the base random number index that is an index indicating the location where the base random number is used needs to match in both the transmission control device 110 and the reception control device 130. There may be a state (synchronized state) in which both base random number indexes do not match due to a communication error or the like.

  In the second embodiment, when an out-of-synchronization state occurs, the transmission control device 110 transmits information for correcting synchronization, and the original synchronization state is obtained, that is, the base random number index is received by the transmission control device 110. An example in which the control device 130 corrects to a matching state will be described. The hardware configuration described with reference to FIG. 2, the secret sharing process (S201), the packet random number transmission process (S202), and the packet random number reception process (S203) described with reference to FIGS. Since it is the same as Example 1, description is abbreviate | omitted and the structure which becomes a difference in Example 2 is demonstrated.

With reference to FIG. 10, an example of the configuration of the in-vehicle system 100 including the synchronization correction will be described. The transmission control apparatus 110 includes a synchronization correction information generation unit 116 and generates synchronization correction information. In addition, the reception control device 130 includes a synchronization correction unit 136 and performs synchronization correction related to the packet random number based on the synchronization correction information received from the transmission control device 110.
Next, an example of an overall outline of communication processing including synchronization processing between the transmission control device 110 and the reception control device 130 will be described with reference to FIG. The secret sharing process (S201), packet random number transmission process (S202), and packet random number reception process (S203) are as already described with reference to FIG. At the time of synchronization correction, as a transmission side synchronization process (S204), the transmission control device 110 generates synchronization correction information (S318), and transmits the generated synchronization correction information (S319).

  On the other hand, the reception control device 130 receives the synchronization correction information from the transmission control device 110 (S327) as the reception-side synchronization processing (S205), and corrects the synchronization based on the received synchronization correction information (S328). The transmission side synchronization process (S204) and the reception side synchronization process (S205) will be further described with reference to FIGS. 12 and 13, respectively.

  In the example of FIG. 11, the process returns to the time of starting the engine after the synchronization correction, but may return to the actual use. Further, when the actual use time has elapsed by a preset number of times or time, the process may be shifted to the synchronization correction time. Further, the transmission control apparatus 110 may transmit one synchronization correction information to a plurality of reception control apparatuses not shown.

(Sender synchronization processing)
An example of the transmission side synchronization process (S204) will be described with reference to FIG. The transmission side synchronization process (S204) is performed by the transmission control apparatus 110 during the synchronization correction. First, the synchronization correction information generation unit 116 of the transmission control device 110 acquires a base random number index (S711), and uses a value obtained by incrementing the acquired base random number index by an appropriate amount as a base random number index after synchronization correction. A communication packet storing the corrected base random number index as synchronization correction information is generated (S712).

  Here, the appropriate amount to be incremented may be, for example, the amount of random numbers already consumed by the transmission control device 110, or the difference between the amount of random numbers already consumed and the obtained base random number value. Alternatively, it may be a preset value. The communication unit 111 of the control device 110 transmits the generated communication packet to the control device 130 via the communication bus 190 (S713).

(Receiver synchronization processing)
An example of the receiving side synchronization process (S205) will be described with reference to FIG. The reception side synchronization process (S205) is performed by the reception control device 130 at the time of synchronization correction. The communication unit 131 of the reception control device 130 receives the communication packet storing the synchronization correction information transmitted by the transmission control device 110 via the communication bus 190 (S811). The synchronization correction unit 136 acquires synchronization correction information from the received communication packet (S812), and performs synchronization correction by setting the acquired synchronization correction information as a base random number index after synchronization correction (S813).

  As described above, even if synchronization error information is generated between the transmission control device 110 and the reception control device 130 due to a communication error, an unauthentic communication packet, or the like, where both base random number indexes do not match, synchronization correction is performed. With information, both base random index can be matched. Then, communication between the transmission control device 110 and the reception control device 130 can be continued.

  In addition, this invention is not limited to the Example mentioned above, A various deformation | transformation is possible within the range of the summary. Even in such a case, there is no essential change in the processing performed in the entire system.

  DESCRIPTION OF SYMBOLS 11 ... Communication apparatus, 12 ... Input / output device, 14 ... CPU, 15 ... Memory, 100 ... In-vehicle system, 110 ... Transmission control apparatus, 111 ... Communication part, 112 ... Communication packet generation part, 113 ... Packet random number transmission control part, DESCRIPTION OF SYMBOLS 114 ... Mask value table storage part, 115 ... Base random number generation part, 116 ... Synchronization correction information generation part, 117 ... Key management part, 118 ... Base random number storage part, 119 ... Mask value table storage part, 130 ... Reception control apparatus, 131: Communication unit, 132: Communication packet verification unit, 133: Packet random number generation unit, 135 ... Base random number generation unit, 136 ... Synchronization correction unit, 137 ... Key management unit, 138 ... Base random number storage unit, 139 ... Mask value table Storage unit, 140 ... reception control device

Claims (6)

An in-vehicle system that connects a plurality of control devices in a communicable manner,
The first controller among the plurality of controllers is
A first base random number storage unit for storing a plurality of base random numbers;
A first mask value storage unit that stores a mask value associated with a packet identifier as a mask value table in association with the packet identifier;
A packet for obtaining and transmitting a base random number corresponding to the length of the packet random number from the first base random number storage unit using a first index indicating a storage location of the base random number in the first base random number storage unit A first packet random number generation unit that obtains a mask value stored in the first mask value storage unit from the identifier and generates a packet random number by exclusive OR of the acquired base random number and the mask value;
A first communication unit that transmits a communication packet obtained by adding the packet random number generated by the first packet random number generation unit to data to be communicated, and
The second controller among the plurality of controllers is
A second base random number storage unit that stores the same base random number as the first base random number storage unit;
A second mask value storage unit that stores the same mask value table as the first mask value storage unit;
A second communication unit that receives a communication packet from the first communication unit;
A packet random number and a packet identifier are acquired from the communication packet received by the second communication unit, and the packet identifier is determined based on the acquired packet identifier and the mask value stored in the second mask value storage unit. A mask value is acquired, a base random number corresponding to the length of the packet random number is acquired from the second base random number storage unit using a second index that is the same as the first index, and the acquired base random number A second packet random number generator for generating a packet random number by exclusive OR of mask values;
An in-vehicle system, comprising: a communication packet verification unit that verifies a communication packet using a packet random number generated by the second packet random number generation unit and a packet random number received from the second communication unit. The first control device includes a base random number generation unit that generates a plurality of base random numbers, and a mask value generation unit that generates a mask value associated with the packet identifier for each packet identifier,
The first communication unit is
When starting the engine of the vehicle, the base random number generated by the base random number generator and the mask value generated by the mask value generator are transmitted to the second control device,
The second communication unit is
Receiving the base random number generated by the base random number generator and the mask value generated by the mask value generator from the first control device;
The second base random number storage unit stores a base random number received by the second communication unit. The second mask value storage unit stores a mask value received by the second communication unit. The in-vehicle system according to claim 1 . The first control device includes:
A synchronization information generating unit that generates synchronization information based on a base random number index that specifies acquisition positions of a plurality of base random numbers stored in the first base random number storage unit;
The first communication unit is
Transmitting the generated synchronization information to the second control device;
The second communication unit is
Receiving the generated synchronization information from the first control device;
The second control device includes:
A synchronization unit that synchronizes a base random number index that specifies acquisition positions of a plurality of base random numbers stored in the second base random number storage unit based on synchronization information received by the second communication unit is provided. The in-vehicle system according to claim 2 . A control method of an in-vehicle system in which a first control device transmits control information to a second control device,
The first control device includes:
A first CPU;
A first memory for storing a mask value associated with each of a plurality of base random numbers and a plurality of identifiers of a packet;
The first CPU is
Using the first index indicating the storage location of the base random number of the first memory, a base random number corresponding to the length of the packet random number is obtained from the first memory, and the first random number is obtained from the identifier of the packet to be transmitted. A mask value corresponding to the identifier of the packet to be transmitted is acquired based on the mask value stored in the memory of the first, and a first packet random number is generated by exclusive OR of the acquired base random number and the mask value;
Transmitting a communication packet obtained by adding the first packet random number to data to be communicated to the second control device;
The second control device includes:
A second CPU;
A plurality of base random numbers that are the same as the first memory, and a second memory that stores a mask value in association with each of a plurality of identifiers of the same packet as the first memory,
The second CPU is
A packet random number and a packet identifier are acquired from the communication packet received from the first control device, a mask value corresponding to the packet identifier stored in the second memory is acquired based on the acquired packet identifier, and the first A base random number corresponding to the length of the packet random number is obtained from the second memory using a second index that is the same as the first index, and a second random number is obtained by exclusive OR of the obtained base random number and the mask value. Generate packet random number,
A control method for an in-vehicle system, wherein a communication packet is verified using the second packet random number and the first packet random number. The first control device includes a base random number generation unit that generates a plurality of base random numbers, and a mask value generation unit that generates a mask value associated with the packet identifier for each packet identifier,
When starting the engine of the vehicle, the base random number generated by the base random number generator and the mask value generated by the mask value generator are transmitted to the second control device,
The second control device includes:
A second communication unit that receives the base random number generated by the base random number generation unit and the mask value generated by the mask value generation unit from the first control device;
The second memory stores a base random number received by the second communication unit,
The on-board system control method according to claim 4, wherein the second memory stores a mask value received by the second communication unit. The first control device includes:
Generating synchronization information based on a base random number index that identifies acquisition positions of a plurality of base random numbers stored in the first memory;
Transmitting the generated synchronization information to the second control device;
The second control device includes:
Receiving the generated synchronization information from the first control device;
The in-vehicle system according to claim 5, wherein a base random number index specifying a plurality of base random number acquisition positions stored in the second memory is synchronized based on synchronization information received by the second communication unit. How to control the system.

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