PAMA: PUF-based Aggregated Multi-hop Attestation Protocol for IoT

An Internet of Things (IoT) engages a large number of resource-constrained edge devices that are internetworked over multi-hop paths. Remote attestation refers to checking the integrity of the software onboard the individual devices (provers) to ensure that it is not maliciously tampered with. Given the scale and the lack of direct communication links, attestation often needs to be conducted over a multi-hop path between a verifier and a prover which raises concern about the integrity and confidentiality of the provided response (digest). To address these issues, this paper proposes PAMA a lightweight attestation protocol utilizing Physical Unclonable Functions (PUFs) to obfuscate the digest and sustain its confidentiality. PAMA does not reveal the actual digest and deprive any node on the dissemination path from even replaying an old attestation response. The response of multiple provers is further aggregated to improve efficiency and scalability while enabling the verifier to authenticate the devices on the path and determine which of them has failed the digest validation if any. PAMA's robustness is rigorously analyzed, and its performance is validated through simulation. The results show that PAMA outperforms competing schemes in terms of runtime complexity, bandwidth efficiency and energy consumption.