On the Security of a Blockchain and PUF-Based Lightweight Authentication Protocol for Wireless Medical Sensor Networks

The advent of the internet of things (IoT) in the global communication network has made everything interconnected and accessible. Therefore, the fields of medicine and diagnosis have emerging trend of using heterogeneous Internet of Medical Things (IoMT). The IoMT makes use of wearable health devices to transfer a huge amount of sensitive medical data to primary servers for diagnosis via a Wireless Medical Sensor Network (WMSN). Although it brings much convenience to patients as well as medical professionals, there are risks of security and privacy breaches. Recently, Wang et al. proposed “Blockchain and PUF-based Authentication Protocol for Wireless Medical Sensor Networks” (DOI 10.1109/JIOT.2021.3117762) for WMSN. Although their protocol deploys security benefits of both the blockchain and PUF technology but cryptanalysis of this protocol shows that the impersonation of the entities involved in the protocol makes it highly vulnerable to eavesdropping, incorrect notion of user anonymity and masquerading attacks. This study pinpoints several security breaches of the said protocol and proposes an enhanced protocol to resolve these security flaws in an invulnerable way. We show that the proposed protocol is safe against various attacks like impersonation, man-in-the-middle, user anonymity and system key leakage using Automated Validation of Internet Security Protocols and Applications tools and Random Oracle Model. We offer pragmatic security analysis and proofs to show that the suggested protocol meets the intended security objectives. Our protocol surpasses four other competitive protocols in terms of computing, communication, and storage costs, according to a thorough performance comparison.