Embedded Elapsed Time Techniques in Trusted Execution Environment for Lightweight Blockchain

Consensus protocols and peer-provided proofs are used to establish trust in blockchain systems. Verifiable proofs that guarantee an elapsed time based on security components have emerged as an alternative to the energy-intensive Proof of Work (PoW). In pursuit of developing a lightweight blockchain suitable for embedded systems, this paper explores the feasibility of constructing a proof mechanism attesting an elapsed time for use in a consensus protocol that is suitable for embedded systems, low-power and that provides a security level at least equivalent to PoW. It introduces the novel Proof of Hardware Time (PoHT), a low-power proof mechanism guaranteeing the elapsed time through standardised secure hardware. Moreover, the elapsed time attestation provided by PoHT cannot be parallelised or delegated. PoHT is compared with PoW and Proof of Sequential Work implementations in terms of energy consumption and elapsed time distribution. An experimental platform is designed to compare proof generation mechanisms under the same conditions. The platform comprises System on Modules that feature an ARM Cortex-A7 processor with a Trusted Execution Environment (TEE) and a Trusted Platform Module (TPM). In addition, PoHT is compared with some of existing state-of-the-art proof mechanisms.