Secure and Trusted Execution: Past, Present, and Future - A Critical Review in the Context of the Internet of Things and Cyber-Physical Systems

Trust has various instantiations: some rely on real-world relationships between entities, while others depend on robust hardware and software technologies to establish it post-deployment. In this paper, we focus on the latter, analyse their evolution in previous years, and their scope in the near future. The evolution of such technologies has involved diverse approaches; consequently, trust is understood and ascertained differently across heterogeneous systems and domains. We look at trusted hardware and software technologies from a security perspective – revisiting and analysing the Trusted Platform Module (TPM); Secure Elements (SE); hypervisors and virtualisation, including Java Card and Intel's Trusted eXecution Technology (TXT); Trusted Execution Environments (TEEs), such as GlobalPlatform TEE and Intel SGX; Host Card Emulation (HCE); and the Encrypted Execution Environment (E3). In our analysis, we focus on these technologies and their application to the emerging domains of the Internet of Things (IoT) and Cyber-Physical Systems (CPS).