PAKAMAC: A PUF-based Keyless Automotive Entry System with Mutual Authentication

Abstract

In recent years, connected and intelligent vehicles have posed advanced risks to road safety and vehicle thefts. The keyless entry and immobiliser systems of luxury vehicles have been under extensive scrutiny and found to be vulnerable against lack of mutual authentication in challenge-response protocol, smaller key size for the cipher, amplification and relay attack, etc. This work presents an initial study to use an unconventional hardware security primitive named Physically Unclonable Functions (PUFs) to nullify such impacts and develop a novel mutual authentication protocol (coined as “PAKAMAC”) to provide an alternative to remote keyless entry (RKE) system and passive keyless entry and start (PKES) system. The proposed scheme generates a hardware fingerprint of the key fob using an embedded PUF instance for unique identification by the vehicle and also leverages two factors, namely time-to-live (TTL) and nonce, to provide secure utility for keyless entry. We have implemented the protocol in Scyther protocol verification tool, and it shows that PAKAMAC satisfies all the security features and can be conveniently applied to automotive systems with minimal hardware overhead and no additional message exchange between the key fob and the car.