Microcontroller based CAN interface

OData support
Dr. Berényi Richárd
Department of Electronics Technology

In my thesis I created a usable device from the very beginning and now it can be used for various operations or for testing any CAN bus which compatible with ISO 11898. I designed the schematic and the layout of the circuit, programmed the microcontroller, created a PC application to drive the hardware device and I tested the circuit and the functions with various setups.

My device is fully compatible with the ISO 11898 standard and can be used with any CAN bus system also implementing that standard. My CAN interface can be connected to two different CAN busses at the same time independently from the speed of the busses. To find the correct baud rate I have created a baud rate scanner procedure which initializes the CAN interface of the microcontroller automatically, so that no human interaction is needed.

With the PC application which also created as part of my work, the usage of the CAN interface is intuitive and convenient. It also facilitates setting up and using enhanced functionality, e.g. message forwarding and filtering options. We can also send messages from this application with different IDs and length to one or two busses and we can follow the whole communication in this application. With the help of this function communication details of unknown CAN busses can be analyzed.

I made numerous tests checking the interface at different CAN speeds, the correct CAN communications and the functions with which the messages can be filtered or modified. Later I checked every function while my device was connected to two different CAN busses. My final test was a Man-in-the-Middle attack. With this attack I modified selected messages between two nodes and neither of the nodes noticed that they are communicating through a proxy connected between them.

SEARCH-LAB Security Evaluation Analysis and Research Laboratory wrote out this thesis to be able to test the security of different CAN busses. With my CAN interface SEARCH-LAB can be performed many types of tests to find possible vulnerabilities and to find a process to avoid these attacks. I hope that this device will serve out SEARCH-LAB and they will be successful at enhancing the safety and security of CAN busses.


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