CovertBC: A Blockchain-Aided Decentralized Authentication Framework for Internet of Things With Covert Channel

Nowadays the flourishing development of communication, network, and sensor technologies has greatly empowered a wide variety of Internet of Things (IoT) applications. However, security and privacy concerns are invoked as tremendous unauthorized sensors and devices are connected with the IoT networks. Nonetheless, traditional resource-consuming authentication methods such as Public Key Infrastructure (PKI) cannot be deployed due to the limited computational and storage capacity of lightweight IoT nodes. When an authentication scheme is aided by blockchain, the trustworthiness and reliability of the authentication results can be improved and distributed computational and storage resources can be collected for authentication. Driven by these issues, we propose a blockchain-aided decentralized authentication framework over covert channels for lightweight IoT networks, named CovertBC. Specifically, the proposed framework orchestrates a physical-layer covert channel design for lightweight identity information transmission and a blockchain-layer consensus mechanism design for trusted and decentralized authentication. First, we develop an off-chain reputation management scheme to evaluate the reputation of the CovertBC nodes according to its correctness on decoding the received covert messages. Second, we propose a reputation-based practical Byzantine fault tolerance consensus protocol, in which the blockchain nodes with high reputation are selected to cooperatively authenticate the accessing node on the chain. Numerical results reveal that CovertBC can achieve higher authentication efficiency than the baseline schemes.