Configurable CAN Device for Cybersecurity with Payload Constraints
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Solution Overview
Problem
In-vehicle networks, particularly Controller Area Networks (CAN), face challenges in implementing cybersecurity due to data field payload limitations, real-time response requirements, limited bandwidth, and compatibility with legacy devices, making it difficult to enable cryptographic operations effectively.
Innovation Solution
A CAN device with a security module connected between the CAN bus interface and the microcontroller communications interface, and an operational mode controller that sets the CAN transceiver to output either a CAN Flexible Data-rate (FD) frame or a corresponding CAN frame, using a programmable cryptographic module to generate Cipher-based Message Authentication Codes (CMAC) and counter values, ensuring secure data transmission while maintaining compatibility with existing network architectures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cryptographic operations are implemented in CAN networks, then cybersecurity is improved, but data field payload limitations and limited bandwidth are worsened
Solution Approach 1:
The cryptographic authentication data is segmented into two parts: a first authentication data (e.g., CMAC digest) with a first identifier, and a second authentication data (e.g., counter value) with a second identifier. This segmentation allows the authentication information to be distributed across multiple CAN frames, bypassing the payload limitation of individual frames while maintaining security integrity.
Solution Approach 2:
The solution moves from a single-dimension approach (embedding all authentication data in one frame payload) to a multi-dimension approach by using multiple identifiers to distinguish different authentication data elements. This dimensional change in data organization allows the system to transmit more authentication information without increasing the payload size of any single frame.
2Reliability
If cryptographic operations are implemented in CAN networks, then cybersecurity is improved, but real-time response requirements are worsened
Solution Approach 1:
The cryptographic authentication data (CMAC digest and counter value) is generated and attached to the data payload in advance, before the data is transmitted on the CAN bus. This preliminary action ensures that authentication is already completed when the frame is received, eliminating any additional processing time at the receiver end and maintaining real-time response requirements.
3Reliability
If cryptographic operations are implemented in CAN networks, then cybersecurity is improved, but device complexity is worsened
Solution Approach 1:
The solution uses the existing CAN FD frame structure and identifier fields for their dual purpose: maintaining frame identification functionality while simultaneously encoding authentication data. By utilizing the FDF bit and identifier fields in combination with the data payload, the system achieves cryptographic authentication without adding separate dedicated authentication channels or modifying the fundamental CAN protocol structure.
Data Source
AI summary
Embodiments of a device and method are disclosed. In an embodiment, a CAN device includes a security module connected between a CAN bus interface of a CAN transceiver and a microcontroller communications interface of the CAN transceiver and an operational mode controller connected between the security module and the CAN bus interface. The security module is configured to perform a security function on data traffic received from the CAN bus interface or from the microcontroller communications interface. The operational mode controller is configured to set an operational mode for the CAN transceiver such that a CAN Flexible Data-rate (FD) frame or a corresponding CAN frame is output from the CAN bus interface. An identifier of the CAN FD frame is the same as an identifier of the corresponding CAN frame.