FlashAttest: Self-Attestation for Low-End Internet of Things via Flash Devices

Abstract

Remote Attestation (RA) is an effective security service that allows a trusted party (verifier) to initiate the attestation routine on a potentially untrusted remote device (prover) to verify its correct state. Despite their usefulness, traditional challenge-response remote attestation protocols suffer from certain limitations, such as challenges in scaling attestation collection and the forced suspension of normal operation during attestation. Self-attestation tackles these issues by enabling the prover to measure its own state asynchronously with the verifier’s attestation request. Existing self-attestation methods rely on hybrid architectures to provide the required security properties, which may not be compatible with low-end Internet of Things (IoT) devices due to hardware limitations. In addition, these protocols currently lack formal verification of design correctness. In this paper, we present FlashAttest, a formally verified self-attestation protocol for low-end IoT devices. FlashAttest leverages the flash device to fulfill the security properties required by self-attestation, eliminating the requirement for hardware modifications. In particular, FlashAttest allows the prover to initiate the attestation routine and guarantee the trustworthiness of the results based on the verified software-based security architecture. By collaborating with the flash device during attestation to generate timestamped reports, FlashAttest enables the verifier to collect and verify the legitimacy of the attestation results. More importantly, FlashAttest achieves strong security guarantees supported by a formally verified design using the Tamarin prover. We implement and evaluate FlashAttest on MSP430 architecture, showing a reasonable overhead in terms of memory footprint, communication overhead, runtime and power consumption. Compared with state-of-the-art self-attestation schemes, our approach achieves similar runtime overhead, low energy consumption, and reasonable memory overhead while eliminating the need for hardware modifications. The results confirm the suitability of FlashAttest for low-end devices.