CAN Bus Physical-Layer Security Using Automatic Node IDs
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Solution Overview
Problem
The lack of unique node addresses in a Controller Area Network (CAN) bus makes it difficult to identify and block malicious nodes that transmit malicious data frames, posing a security risk to automotive electronic systems, and existing methods of assigning unique IDs either reduce transmission efficiency or require cumbersome reassignment upon part replacement.
Innovation Solution
A counterattack method involving unique node IDs (NIDs) automatically assigned upon CAN bus boot-up, with an intrusion detection system (IDS) detecting error frames and increasing error counters to block hacked nodes entering a bus-off state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If unique IDs are assigned to each node in hardware when producing a CAN controller, then node identification capability is improved, but the number of bits of the unique ID is greatly increased, reducing transmission efficiency
Solution Approach 1:
The patent assigns unique IDs to each node in advance during controller production, storing them in non-volatile memory. This preliminary assignment eliminates the need for dynamic ID allocation during runtime, enabling efficient identification without consuming additional communication bandwidth.
2Device complexity
If unique IDs are assigned collectively at a factory after all nodes are mounted on the CAN bus, then the number of bits of the unique ID is reduced, but ID reassignment is required whenever parts are replaced
Solution Approach 1:
Each node contains its unique ID permanently stored in its own controller's non-volatile memory. The node uses its own stored ID for identification purposes, eliminating the need for centralized factory reassignment when parts are replaced. Each node is self-sufficient in maintaining its identity.
3Reliability
If software operations are used to check processor ID and encryption key for communication, then communication security is improved, but advanced hacking can tamper with all software operations, allowing attackers to ignore blocking commands
Solution Approach 1:
The patent introduces a hardware-based intrusion detection system that acts as an intermediary between the communication parties. This independent hardware monitor checks for malicious activities such as abnormal transmission frequencies and content patterns, providing an additional security layer that cannot be tampered with through software operations alone.
4Productivity
If the CAN bus does not have address functionality like MAC address of Ethernet, then simultaneous transmission and multiple transmissions are enabled, but it becomes difficult to identify which node transmits malicious data frames
Solution Approach 1:
The patent segments the identification function from the communication address function. While the CAN bus maintains its address-less communication structure for efficiency, each node is equipped with a unique ID stored in its controller that can be used for identification purposes when needed, such as when detecting or tracking malicious activities.
Data Source
AI summary
A counterattack method against a hacked node in a controller area network (CAN) bus physical layer includes: setting node IDs (NIDs), which are different unique IDs, for each of a plurality of nodes connected to a CAN bus line; determining that an error frame is generated when at least one of a node using a forged NID, a node using a different NID, and a node using a non-existent NID is found; increasing counts of a transmit error counter (TEC) and a receive error counter (REC) of a transmitting node and a receiving node whenever the error frame is generated; and allowing a node of which the count of the TEC or REC is greater than a set threshold value to enter a bus-off state to block the node.