CAN Bus ECU Key Management for Secure Communication
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Solution Overview
Problem
IoT devices, particularly automotive ECUs, are vulnerable to cyber-attacks due to lack of robust end-to-end communication security, allowing spoofing and eavesdropping on networks like CAN bus, which can compromise vehicle control systems.
Innovation Solution
Implementing a method for managing and synchronizing symmetric keys and message counters across ECUs to establish and maintain secure communication channels, ensuring only authorized devices can decode messages, without requiring additional data exchange that could overload networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If symmetric keys and message counters are exchanged between ECUs to maintain synchronization, then communication security is improved, but network traffic overhead increases
Solution Approach 1:
Each ECU independently generates and maintains its own message counter and symmetric key without requiring synchronization messages from other ECUs. The sending ECU increments its counter locally, and the receiving ECU independently increments its counter based on received message sequences, allowing both parties to maintain synchronized state without explicit key exchange traffic
Solution Approach 2:
ECUs pre-establish symmetric keys and message counters during system initialization or secure boot sequences before normal communication begins. This preliminary setup eliminates the need for ongoing key exchange traffic during operational communication, as ECUs can independently maintain synchronization using their pre-configured security parameters
2Reliability
If additional synchronization data is transmitted between ECUs, then key synchronization is improved, but network bandwidth consumption increases
Solution Approach 1:
The receiving ECU independently tracks and increments its message counter by monitoring the sequence of received messages, eliminating the need for the sending ECU to transmit counter values or synchronization data. Each ECU serves itself by maintaining its own synchronization state through local processing of communication sequences
Solution Approach 2:
The synchronization function is extracted from the communication data stream itself. Instead of embedding synchronization information within message payloads or requiring separate synchronization channels, the system uses the inherent message sequence structure to drive counter incrementation, extracting synchronization signals from the natural flow of authenticated communication
3Reliability
If message counters are incremented for each message, then security freshness is improved, but processing complexity increases
Solution Approach 1:
The counter management function is segmented into independent, message-level operations. Each message triggers an individual counter increment operation that is simple and deterministic, avoiding the need for complex counter management logic. The segmentation of security operations into discrete, incremental steps reduces overall processing complexity while maintaining security freshness
Solution Approach 2:
The counter increment operation is designed as a self-service function that automatically executes with each message processing event. The ECU's message handling routine inherently includes counter incrementation as a built-in step, eliminating the need for separate counter management procedures or complex state machine logic
Data Source
AI summary
Technology can be used for sending and receiving messages on a CAN bus with a plurality of ECUs. The technology can include identifying a first message to send to a receiving ECU from a sending ECU; incrementing a sender-version message counter for the message type; determining to create a second session for the message type in the sending ECU; generating a second sender-version session key to be used during the second session in the sending ECU; and resetting the sender-version message counter. The technology further includes processing the first message using the second sender-version session key, including performing an operation to combine the sender-version message counter with the first message to create a combined message and encoding the combined message using the second sender-version session key to create an encoded message. The technology further includes sending the encoded message to the receiving ECU on the CAN bus.