Graduate Seminar with Tim Dee: Securing CAN

When

November 12, 2018    
1:10 pm - 2:00 pm

Where

2222 Coover Hall
2520 Osborn Drive, Ames, Iowa, 50011-1046

Event Type

Speaker: Tim Dee, ECpE Graduate Student

Advisor: Akhilesh Tyagi

Title: Securing CAN

Abstract: A Controller Area Network (CAN) bus allows sending information over small distances. It is frequently used in automotive, off-road, and industrial environments. A CAN bus is frequently a real-time bus; these are used to send data and control messages. Control messages can cause an actuator to perform some action. An adversary might observe the control message and subsequent action. Injecting the control message at a later time (replay attack) should not affect the same action. Unfortunately CAN currently provides no protection against such attacks. Third party components may reverse engineer messaging protocols to gain control over critical systems resulting in dangerous system malfunctions. A solution is to verify the integrity and authenticity of messages. Verifying the integrity of a freshness value appended to messages prevents replay attacks. Authenticity guarantees messages do not come from a malicious party. A keyed hash function using a shared secret key produces values guaranteeing authenticity. The challenges are: (1) establishing a shared secret and (2) synchronizing a freshness value. Past standards limit CAN message sizes to 8 bytes. New standards (CAN-FD) allow for longer messages. We propose appending 8 bytes to messages to provide integrity and authenticity. Nodes require a shared key and freshness value for creating these bytes. Scenarios exist requiring shared key renegotiation to ensure the key remains secret. The shared key is negotiated using Elliptic Curve Cryptography (ECC) infrastructure. Protocols are developed for establishing a shared key and synchronizing a freshness value. Protocol correctness is verified through simulations.

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