KR101705639B1 - Method for transmitting and receiving a message in a vehicle network system - Google Patents

Abstract

Disclosed is a message transmission and reception method. The message transmission and reception method is a method for transmitting and receiving a message in a vehicle network system including a plurality of sub-networks, and comprises the steps of: generating, by a transmission (electronic control unit (ECU)) included in a first one of the plurality of sub-networks, a first message, and transmitting, by the transmission ECU, to a first message transmission gateway ECU included in the first sub-network; extracting, by the transmission gateway ECU, an ID and data from the first message, and generating, by the transmission gateway ECU, a cryptogram by encrypting the extracted ID, the extracted data and a counter value; generating, by the transmission gateway ECU, a second message including the cryptogram, and transmitting, by the transmission gateway ECU, the second message to a reception gateway ECU of a second sub-network in which a reception ECU is included; decoding, by the reception gateway ECU, the cryptogram included in the second message, and determining, by the reception gateway ECU, data integrity by using a result of the decoding; when data integrity is acknowledged, generating, by the reception gateway ECU, a third message including data generated as the result of the decoding; and transmitting, by the reception gateway ECU, the third message to the reception ECU.

Description

[0001] METHOD FOR TRANSMITTING AND RECEIVING A MESSAGE IN A VEHICLE NETWORK SYSTEM [0002]

The present invention relates to a method of transmitting and receiving messages in a vehicle network system, and more particularly, to a method and apparatus for transmitting and receiving messages in a vehicle network system, And a method of transmitting and receiving a message capable of protecting a communication message.

As the technology related to automobiles develops, various kinds of electronic control units (ECUs) are mounted in the vehicle. Currently, more than 200 ECUs are mounted on the vehicles. It contributes to the safety and convenience of the driver through the mounted ECU. Typical examples of in-vehicle network protocols for such ECU communication are CAN (Controller Area Network) and CAN FD (CAN with Flexible Data Rate). However, CAN and CAN FD are designed based on the network of the bus structure of the broadcasting system, so that it is possible to collect communication messages between ECUs by external eavesdropping, which poses a security problem. Also, it may be very vulnerable to a retransmission attack made through the information thus collected. In this specification, in order to solve such a security problem, the present invention attempts to solve a problem of a retransmission attack due to message leakage due to encrypted communication through message encryption and data encapsulation.

Korean Patent Publication No. 10-2016-0060683 (published on May 30, 2016) Korean Patent Laid-Open No. 10-2015-0024117 (published on May 30, 2015)

The technical problem to be solved by the present invention is to encapsulate and encrypt the CAN message ID and data transmitted by the ECU in the CAN FD format to secure the confidentiality and integrity, And a method for transmitting and receiving a message.

A method of transmitting and receiving a message in a vehicle network system including a plurality of subnetworks, the method comprising: transmitting an electronic control unit (ECU) included in a first subnetwork of the plurality of subnetworks; Generating a first message and transmitting the first message to a transmission gateway ECU included in the first subnetwork, the transmission gateway ECU extracting an ID and data from the first message, Generating a cipher text by encrypting the extracted ID, extracted data, and a counter value, the transmission gateway ECU generating a second message including the cipher text, receiving the second message To the reception gateway ECU of the second sub-network including the ECU, the reception gateway ECU transmits the second mesh Decrypting a ciphertext included in the decryption result and determining data integrity using the decryption result; and if the data integrity is recognized, the receiving gateway ECU generates a third message including data generated as a result of decryption And the reception gateway ECU transmitting the third message to the reception ECU.

According to the message transmission / reception method according to the embodiment of the present invention, data confidentiality and integrity can be guaranteed through encapsulation of data and encryption of a message.

In addition, according to the message transmission / reception method according to the embodiment of the present invention, it is possible to provide a message transmission / reception method in a vehicle network system that is safe from a replay attack.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to more fully understand the drawings recited in the detailed description of the present invention, a detailed description of each drawing is provided.
1 shows a vehicle network system according to an embodiment of the present invention.
2 is a flowchart illustrating a method of transmitting and receiving a message in the vehicle network system shown in FIG.
FIG. 3 shows the format of the CAN FD message generated by the transmission gateway ECU shown in FIG.

It is to be understood that the specific structural or functional description of embodiments of the present invention disclosed herein is for illustrative purposes only and is not intended to limit the scope of the inventive concept But may be embodied in many different forms and is not limited to the embodiments set forth herein.

The embodiments according to the concept of the present invention can make various changes and can take various forms, so that the embodiments are illustrated in the drawings and described in detail herein. It should be understood, however, that it is not intended to limit the embodiments according to the concepts of the present invention to the particular forms disclosed, but includes all modifications, equivalents, or alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms may be named for the purpose of distinguishing one element from another, for example, without departing from the scope of the right according to the concept of the present invention, the first element may be referred to as a second element, The component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having" and the like are used to specify that there are features, numbers, steps, operations, elements, parts or combinations thereof described herein, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning of the context in the relevant art and, unless explicitly defined herein, are to be interpreted as ideal or overly formal Do not.

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

1 shows a vehicle network system according to an embodiment of the present invention.

Referring to FIG. 1, a vehicle network system 10 includes a plurality of subnetworks, each of which includes at least one gateway electronic control unit (ECU) and at least one ECU. Although only three subnetworks are shown in FIG. 1, the present invention is not limited thereto. The vehicle network system 10 may include n (n is a natural number of 2 or more) subnetworks according to an embodiment.

Each subnetwork may include at least one gateway ECU and a plurality of ECUs. That is, the first sub-network 100 includes a first gateway ECU 110 and a plurality of first ECUs 120. The second sub-network 200 includes a second gateway ECU 210, 2 ECUs 220 and the third sub-network 300 may include a third gateway ECU 310 and a plurality of second ECUs 320.

The plurality of gateway ECUs included in each subnetwork may share the shared key used in the process of generating or decrypting the ciphertext in advance. In addition, each of the ECUs can maintain a synchronized counter value, thereby providing a method of transmitting and receiving a message secure from a re-transmission attack.

According to an embodiment, the vehicle network system 10 may further include an On-Board Diagnostic (OBD) terminal 400.

2 is a flowchart illustrating a method of transmitting and receiving a message in the vehicle network system shown in FIG.

1 and 2, the message is included in the vehicle network system 10 from any one of a plurality of ECUs included in one of the subnetworks included in the vehicle network system 10, that is, the transmission ECU Is transmitted to any one of a plurality of ECUs included in another sub-network, that is, the receiving ECU. In addition, CAN FD is used for communication between gateway ECUs during transmission and reception of messages, and CAN is used for communication between ECUs and gateway ECUs included in the sub-network.

First, the transmission ECU generates a message (S100). The message generated by the sending ECU may be a CAN message. The generated message can be transmitted by the transmission ECU to the transmission gateway ECU included in any one of the subnetworks. Here, the transmission ECU can transmit a message generated by broadcasting the generated message.

The transmission gateway ECU may extract the CAN ID and data from the message received from the transmission ECU (S210) and generate a ciphertext for transmission to the gateway ECU of the subnetwork including the reception ECU, that is, the reception gateway ECU (S220). The CAN ID means an ID of an ECU that transmits a message, or it may mean a packet ID.

), 추출된 데이터(

) 및 카운터값(

)을 이용하여, 암호문을 생성할 수 있다. 구체적으로, 상기 송신 게이트웨이 ECU는 공유키를 이용하여

를 암호화할 수 있다. 여기서,

는 이어쓰기(concatenation) 연산을 의미할 수 있다. 또한, 사용되는 암호 알고리즘은 AES(Advanced Encryption Standard) 알고리즘일 수 있으나, 본 발명의 권리범위가 이에 한정되는 것은 아니다.The transmission gateway ECU transmits the extracted CAN ID (

), Extracted data (

) And counter value (

) Can be used to generate a cipher text. Specifically, the transmission gateway ECU uses the shared key

Can be encrypted. here,

May refer to a concatenation operation. Also, the encryption algorithm used may be an AES (Advanced Encryption Standard) algorithm, but the scope of the present invention is not limited thereto.

Then, the transmission gateway ECU generates a CAN FD message and transmits the generated CAN FD message to the reception gateway ECU (S230). At this time, the transmission gateway ECU can transmit the CAN FD message by broadcasting the CAN FD message. The format of the CAN FD message will be described in detail with reference to FIG.

When a CAN FD message is transmitted by the transmission gateway ECU, each of the gateway ECUs can increase the count value by 1 (S240, S310). Thus, a secure communication technique can be provided from a re-transmission attack.

When a CAN FD message is transmitted by the transmission gateway ECU, each of the gateway ECUs can know the destination of the message through the Sender ECU ID included in the CAN FD message. The receiving gateway ECU decrypts the cipher text included in the CAN FD message (S320), and determines the integrity or data integrity of the message using the decryption result (S330). That is, it is possible to compare the counter value included in the cipher text with the counter value held by the reception gateway ECU, and determine whether the message is integrity based on the comparison result. If the reception gateway ECU determines that the counter value has increased after receiving the message and that the difference between the counter values to be compared is 1, the integrity is satisfied. If the reception gateway ECU increases the counter value after determining the integrity, Should be the same to satisfy the integrity. Therefore, the increase timing of the counter value by the reception gateway may be different according to the embodiment. That is, according to the embodiment, it is possible to increase the counter value after determining the integrity.

The receiving gateway ECU generates a CAN message using the decoded result, and the generated CAN message can be transmitted to the receiving ECU (S340).

As described above, the message transmission / reception method according to the present invention can protect a communication message from an external replay attack by ensuring confidentiality and integrity of data through data encapsulation and message encryption.

In addition, the present invention maximizes the use of CAN, which has proven to be safe in terms of functional safety, and enables various encryption algorithms to be applied using a CAN FD having a wider payload than CAN. This ensures the confidentiality and integrity of the message in the network environment of the vehicle, thereby enhancing the reliability of the communication between the ECUs.

FIG. 3 shows the format of the CAN FD message generated by the transmission gateway ECU shown in FIG.

Referring to FIGS. 1 to 3, the data frame of the CAN FD includes a data field of 64 bytes. 3 bytes are allocated to the counter value (Counter) of the 64-byte data field, 2 bytes are assigned to the Sender ECU ID, and 59 bytes are assigned to the ciphertext (Encrypt Data). The counter value, Sender ECU ID, and ciphertext allocation order and allocation size shown in FIG. 3 may differ according to the embodiment.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

10: Vehicle network system
100: first sub-network
110: first gateway ECU
120: first ECUs
200: second subnetwork
210: a second gateway ECU
220: second ECUs
300: Third subnetwork
310: Third gateway ECU
320: Third ECUs
400: OBD terminal

Claims (7)

A method of transmitting and receiving a message in a vehicle network system including a plurality of subnetworks,
Generating a first message by an electronic control unit (ECU) included in a first sub-network of the plurality of sub-networks, and transmitting the first message to a transmission gateway ECU included in the first sub-network;
Extracting an ID and data from the first message and encrypting the extracted ID, extracted data and a counter value to generate a cipher text;
The transmission gateway ECU generates a second message including the cipher text and transmits the second message to a reception gateway ECU of a second sub network including a reception ECU;
Decrypting the cipher text included in the second message by the reception gateway ECU and determining data integrity using the decryption result;
Generating a third message including data generated as a result of the decoding if the data integrity is recognized; And
And the reception gateway ECU transmitting the third message to the reception ECU,
Wherein the reception gateway ECU compares a counter value generated as a result of decoding with a counter value held by the reception gateway ECU to determine data integrity,
A method for transmitting and receiving a message.
The method according to claim 1,
Wherein the first message and the third message are CAN messages,
Wherein the second message is a CAN FD message,
A method for transmitting and receiving a message.
The method according to claim 1,
Wherein the transmission gateway ECU generates the ciphertext using the shared key shared by the transmission gateway ECU and the reception gateway ECU,
A method for transmitting and receiving a message.
delete The method according to claim 1,
After the step of transmitting the second message to the reception gateway ECU of the second sub-network including the reception ECU,
Wherein each of the transmission gateway ECU and the reception gateway ECU increments a counter value.
A method for transmitting and receiving a message.
A method of transmitting and receiving a message in a vehicle network system including a plurality of subnetworks,
Generating a first message by an electronic control unit (ECU) included in a first sub-network of the plurality of sub-networks, and transmitting the first message to a transmission gateway ECU included in the first sub-network;
Extracting an ID and data from the first message and encrypting the extracted ID, extracted data and a counter value to generate a cipher text;
The transmission gateway ECU generates a second message including the cipher text and transmits the second message to a reception gateway ECU of a second sub network including a reception ECU;
Decrypting the cipher text included in the second message by the reception gateway ECU and determining data integrity using the decryption result;
Generating a third message including data generated as a result of the decoding if the data integrity is recognized; And
And the reception gateway ECU transmitting the third message to the reception ECU,
Wherein the first message and the third message are CAN messages,
The second message is a CAN FD message,
The data field of the second message includes a counter value, an ID (Sender ECU ID) of the transmission ECU,
A method for transmitting and receiving a message.
The method according to claim 6,
3 bytes are allocated to the counter value in the data field of the second message, 2 bytes are allocated to the ID of the transmission ECU, and 59 bytes are allocated to the ciphertext.
A method for transmitting and receiving a message.

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