RAKSH: A Blockchain Derived In-Vehicle Key Management System

Modern cars have advanced significantly with the rapid growth of connectivity and communication technologies. In the wake of rising cyberattacks and enforcement of regulations, implementation of cybersecurity is imperative to safeguard vehicles. The cybersecurity controls such as secure boot, secure updates, secure communication require cryptographic primitives (keys/certificates). These security features are largely dependent on robust Key Management System (KMS), as keys are the sensitive assets that must be protected throughout the lifecycle of vehicle. Several security critical applications like over-the-air and car-to-car interaction essentially needs robust KMS to protect the vehicle assets from expanding attack vector. Traditionally KMS is established centrally in a backend server. The cloud based KMS is becoming complex due to increased number of keys/certificates required to provision in a vehicle. We propose a self-governing in-vehicle key management system for a gateway-based architecture. The solution is derived from core principles of Blockchain technology. Every key or certificate transaction is recorded in a registry, with the first block (genesis block) created during the vehicle manufacturing stage by the gateway. The first stage involves creation of a genesis block, followed by the generation of a PKI blockchain for each ECU during vehicle manufacturing. In the second stage, the established PKI blockchain will be utilized for secure on-road communication during vehicle operations. Key management operations such as key rotation, revocation, addition, and replacement will be performed based on the established blockchain, with the gateway serving as the anchor point. Each key management operation is appended to the chain starting from the genesis block, with updates securely broadcast and replicated across all ECUs ensuring a distributed, tamper-proof key management framework. Several diverse communications like CAN, CAN-FD and Ethernet are comparatively analyzed, against its usage, benefits and complexity in the proposed approach.