Networks of Trusted Execution Environments for Data Protection in Cooperative Vehicular Systems

Networks of autonomous vehicles roaming in smart cities raise new challenges for end-to-end protection of data in terms of integrity, privacy, efficiency, and scalability. This paper provides a survey of Networks of Trusted Execution Environments (NTEE) architectures. NTEE combine the strong, hardware-rooted security guarantees of the TEE deployed locally in the vehicle, with the distributed protection of a decentralized consensus protocol. We identify three main families of consensus protocols and analyze their architectures, performance, and security, including improvements brought by the TEE. Overall, voting protocols tend to be more efficient for smaller networks, while lottery-based schemes are not easy to apply in a vehicular context due to higher overheads. Both types of protocols reach an intermediate level of security, with variations in byzantine tolerance and types of threats. Graph based protocols tend to achieve both efficiency and flexibility in terms of network topology support, but their security still remains to be explored.