CAN Message Authentication Using Logical Bus Identifiers
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Solution Overview
Problem
The Controller Area Network (CAN) protocol lacks data authentication and privacy, making it susceptible to attacks, especially with the increasing exposure of in-vehicle networks to external entities, which poses serious security and safety risks, particularly in critical systems like braking and airbag systems.
Innovation Solution
An efficient security protocol is introduced that adds a logical bus identifier and authentication code to each message frame, using a cryptographic hash function based on a secret logical bus key specific to each group of nodes, ensuring only authorized nodes within the same group can verify the authenticity of messages, thus preventing illegitimate messages from disrupting critical systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data authentication and privacy protection are added to CAN protocol, then security is improved, but device complexity and processing requirements increase
Solution Approach 1:
The authentication mechanism is segmented into distinct components: logical bus identifiers for group segmentation, cryptographic engines for authentication code generation, and filter units for verification. This segmentation allows security functionality to be added without requiring complete redesign of the CAN protocol, thereby improving security while managing complexity through modular architecture.
Solution Approach 2:
Authentication codes serve as intermediaries between sending and receiving nodes, enabling verification of message authenticity without requiring direct trust relationships. The cryptographic hash function acts as an intermediary mechanism that transforms message data into verifiable authentication codes, adding security without requiring complex peer-to-peer verification protocols.
2Reliability
If authentication codes and logical bus identifiers are added to each message frame, then message authenticity is improved, but message size and transmission overhead increase
Solution Approach 1:
The authentication mechanism uses parameter changes in the message frame structure by adding logical bus identifiers and authentication codes. These parameters are efficiently encoded and integrated into the existing CAN frame format, minimizing the increase in message size while providing comprehensive authentication capability.
3Reliability
If cryptographic verification is performed at each receiving node, then security against unauthorized access is improved, but processing time and energy consumption increase
Solution Approach 1:
Authentication codes are pre-computed using cryptographic hash functions at the sending node before message transmission. Receiving nodes perform verification by comparing the received authentication code with a locally computed value, rather than performing full cryptographic verification. This preliminary action at the sending node significantly reduces processing time and energy consumption at receiving nodes while maintaining security.
Data Source
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AI summary
The present application relates to an apparatus and method of authenticating and verifying a message frame on a multi-master access bus with message broadcasting. Logic bus identifier, LID, are associated with each one of a several logical groups of nodes out of a plurality of nodes connected to the multi-master access bus. A key is assigned to each logical group. The keys assigned to different logical groups differ from each other. For message authentication, a logic bus identifier, LID is provided and a key associated with the logic bus identifier, LID, is retrieved. A cryptographic hash value, MAC, is generated using the retrieved key and based on at least the logic bus identifier, LID. A message frame is composed, which comprises the logic bus identifier, LID, and the cryptographic hash value, MAC. For message verification, a message frame is received, which comprises at least a logic bus identifier, LID, and a cryptographic hash value, MAC. A key is retrieved, which is associated with the logic bus identifier, LID, extracted from the frame. A cryptographic verification hash value, VAC, is generated using the retrieved key and based on at least the logic bus identifier, LID. The cryptographic verification hash value, VAC, and the cryptographic hash value, MAC, extracted from the frame are compared. The received message frame is forward for further processing as a legitimate message frame.