TJET: Ternary Join-Exit-Tree Based Dynamic Key Management for Vehicle Platooning

Vehicle platooning, which is formed by a group of vehicles traveling in close proximity to one another, nose-to-tail, at highway speeds, has received considerable attention in recent years. However, though it brings many opportunities in self-driving, the security of vehicle platooning is still challenging. In this paper, to secure vehicle platooning, particularly to secure communication and efficient key updating for vehicles in a platoon, we first present the notion of ternary join exit tree. A ternary join exit tree consists of main tree, join tree, and exit tree. The users join in the join tree and leave from exit tree. Then, we propose a new dynamic ternary join-exit tree-based dynamic key management scheme, called TJET, for vehicle platooning, which is characterized by providing efficient key updating for not only vehicle joining and leaving, but also platoon merging and splitting. Specifically, based on the structure of ternary join-exit tree, we devise concrete algorithms for vehicle joining, vehicle exiting, platoon merging, and splitting. Moreover, we also analyze the capacities and activation conditions of join tree and exit tree based on strict mathematical proofs. Detailed security analysis show that our proposed TJET holds desirable security properties including forward security, backward security, and resistance to key control. In addition, performance evaluations via extensive simulations demonstrate the efficiency of TJET.