Blockchain-Aided Decentralized Trust Management of Edge Computing: Toward Reliable Off-Chain and On-Chain Trust

As a shared and distributed database, blockchain empowers distributed edge computing (EC) networks with decentralization, integrity, and auditability of trust management. However, a bottleneck issue of blockchain-enabled decentralized trust management (B-DTM) lies in off-chain trust verification, since blockchain is a guarantee of on-chain trustworthiness rather than the reliability of off-chain trust. To orchestrate the off-chain and on-chain trust, we develop a novel B-DTM framework for EC networks that features off-chain trust verification and on-chain trust based consensus mechanisms. In the off-chain environment of EC, each edge node gains its verifiable trust according to Quality of Task Execution (QoTE). Furthermore, we justify that verified off-chain trust can be used as stake for the on-chain consensus. In particular, we design a novel consensus mechanism called Proof-of-Trusted-Work (PoTW), wherein the difficulty adjustable mining work and chain structure of trust data are introduced to promote the on-chain trust security and the trust based mining difficulty adjustment is employed to improve the on-chain trust update efficiency. Simulation results demonstrate the efficiency and security performances of the proposed B-DTM against various on-chain and off-chain malicious attacks.