CAN Transceiver Security Module and Shield Device
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Solution Overview
Problem
Conventional CAN networks are limited by their 8-byte payload capacity, which complicates the deployment of message integrity mechanisms like CMAC signatures, leading to increased network traffic and security vulnerabilities, and the transition to CAN FD format is hindered by the need for compatible microcontrollers and potential data throughput bottlenecks.
Innovation Solution
A CAN transceiver with a security module and shield device that blocks CAN FD traffic from reaching classic CAN microcontrollers, using a programmable cryptographic module to encrypt and decrypt data, and an FD protocol controller to manage CAN FD frames, ensuring message integrity and compatibility with both classic and CAN FD microcontrollers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If message integrity mechanisms like CMAC signatures are deployed in conventional CAN networks, then security is improved, but network traffic increases and payload capacity is exceeded due to the 8-byte limit
Solution Approach 1:
The patent transitions from conventional CAN to CAN FD (Flexible Data-rate), changing the data rate parameter and payload capacity from 8 bytes to up to 64 bytes. This parameter change allows CMAC signatures and other security mechanisms to be deployed without exceeding payload limits, as the expanded capacity can accommodate both data and security overhead.
Solution Approach 2:
The patent introduces a shield device that creates a separate communication dimension between the CAN bus and the microcontroller. This shield intercepts and processes CAN FD frames, separating security-critical traffic from classic CAN traffic, allowing security mechanisms to operate in a dedicated channel without increasing overall network traffic burden.
2Quantity of substance
If CAN FD format is adopted to enable security mechanisms, then payload capacity is improved, but compatibility with classic CAN microcontrollers deteriorates
Solution Approach 1:
The shield device acts as an intermediary between the CAN bus and classic CAN microcontrollers. It receives CAN FD frames, extracts security-critical data, and communicates with classic microcontrollers through a compatible interface (such as SPI). This intermediary allows classic microcontrollers to benefit from CAN FD security mechanisms without requiring native CAN FD support.
Solution Approach 2:
The patent segments the communication system into two parts: a CAN FD interface for high-capacity security traffic and a classic CAN interface for legacy compatibility. The shield device manages this segmentation, routing appropriate traffic to appropriate interfaces, allowing the system to support both CAN FD and classic CAN microcontrollers simultaneously.
3Adaptability or versatility
If a shield device is introduced to block CAN FD traffic from classic microcontrollers, then compatibility is improved, but device complexity increases
Solution Approach 1:
The shield device is designed with multi-functionality to justify its added complexity. It can operate in multiple modes: blocking CAN FD traffic from classic microcontrollers, routing CAN FD traffic to security modules, and providing a compatibility interface for classic microcontrollers. This universal design allows a single component to address multiple compatibility issues.
Solution Approach 2:
The shield device implements self-service by autonomously monitoring incoming CAN traffic, identifying CAN FD frames, and automatically routing or blocking them based on the capabilities of connected microcontrollers. This self-service capability reduces the need for external control logic and simplifies system integration despite the added component.
Data Source
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AI summary
Embodiments of a device and method are disclosed. In an embodiment, a Controller Area Network (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 a shield device connected between the CAN bus interface and the microcontroller communications interface. The security module is configured to perform a security function on data traffic received from the CAN bus interface or from a Serial Peripheral Interface (SPI) interface of the microcontroller communications interface. The shield device is configured to direct CAN Flexible Data-rate (FD) traffic received from the CAN bus interface to the security module.