$\mu$-Trust: Trustworthy and Transparent Service Composition for Microservice-Based IoT Systems

The distributed Internet of Things (IoT) systems facilitate real-time services through the composition of loosely coupled microservices. The composed IoT service is the output of multiple microservices, executed at computationally capable edge or fog nodes, which we consider as the facility nodes (FNs). However, the service composition process in IoT microservice architectures is abstracted from the users that gives freedom to the FNs to act maliciously and provide low-quality IoT services. Further, the service composition needs to be transparent so that the FNs involved in a service cannot repudiate their involvement at a later time. In this article, we propose a novel, lightweight, trustworthy, and verifiable service composition framework for IoT-based systems that adopt microservice architecture. First, we propose a dynamic programming approach to select trustworthy FNs for each user request, while considering the trust scores of the FNs and the delay requirements of the users. Next, we propose a transparent service composition framework that uses lightweight cryptography functions to generate the proof-of-involvement for the FNs in each service. With the help of a trust controller, we verify the proofs generated by the FNs and update the trust scores of the FNs. Considering the user traces from Berlin city in the simulation of urban mobility tool, we show the efficacy of the proposed framework in maximizing user trust and detecting malicious FNs involved in user services. Further, we show that the delay and communication overhead of the proposed framework are very low compared to the state-of-the-art methods.