CAN Message Authentication Using Global and Local Counters
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Solution Overview
Problem
The CAN message authentication mechanism in vehicle networks is prone to errors due to counter value desynchronization, leading to potential misauthentication of messages and compromising network security and vehicle safety.
Innovation Solution
Implement a method where devices use local and global counters to verify CAN messages, synchronizing counter values through a gateway or domain manager device, and employing verification codes based on full counter values and shared keys to ensure message authenticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only local counter values are used for CAN message authentication, then the authentication process is simple and fast, but counter value desynchronization occurs leading to authentication errors and security vulnerabilities
Solution Approach 1:
The counter value is segmented into two parts: a local counter (lower bits) that increments with each message and a global counter (upper bits) that changes periodically. This segmentation allows the system to maintain simple local authentication while periodically synchronizing with global counter updates, preventing desynchronization without requiring complex continuous synchronization mechanisms.
Solution Approach 2:
The global counter value is updated periodically rather than continuously. A gateway or domain manager device broadcasts updated global counter values at regular intervals, allowing receiving devices to synchronize their local counters with the global counter periodically. This periodic action maintains authentication accuracy while avoiding the complexity of continuous synchronization.
2Reliability
If the counter value is carried in every CAN message, then message authentication is possible, but the message payload capacity is reduced due to limited CAN data field size
Solution Approach 1:
The counter is divided into local and global segments, with only the local counter (lower bits) being carried in each CAN message. The global counter (upper bits) is updated periodically through separate synchronization messages. This segmentation reduces the counter storage requirement in individual messages while maintaining full authentication capability through periodic global counter updates.
3Reliability
If counter values are synchronized frequently, then authentication accuracy is maintained, but network traffic and processing overhead increase
Solution Approach 1:
Counter synchronization is performed periodically rather than continuously. The gateway or domain manager device updates global counter values at predetermined intervals, and receiving devices synchronize their local counters at these same intervals. This periodic synchronization maintains authentication accuracy while minimizing network traffic and processing overhead compared to continuous synchronization.
Data Source
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AI summary
Embodiments of this application provide an information transmission method, a communications device and system, and a computer-readable storage medium, and are applicable to information exchange inside an intelligent vehicle in the field of autonomous driving. In the embodiments of this application, a full counter value maintained by each ECU device includes a global counter value and a local counter value. The global counter value keeps globally synchronized in an entire CAN network, and the local counter value is obtained by each device performing counting by using a local counter. In this way, when a second device sends a CAN message, the CAN message carries a second counter value. When receiving the CAN message, the first device may determine whether a locally maintained first counter value matches the second counter value. If the locally maintained first counter value does not match the second counter value, the CAN message may be verified by using the second counter value and the global counter value. In this way, the technical solutions provided in the embodiments of this application can improve security and stability of an in-vehicle network of the intelligent vehicle.