An Efficient Blockchain Assisted Reputation Aware Decentralized Federated Learning Framework

Because of the widespread presence and ease of access to the Internet, edge devices are the perfect candidates for providing quality training on a variety of applications. However, their participation is restrained due to potential leakage of sensitive and private data. Federated learning targets to address these issues by bringing the model to the device and keeping the data in place. Still, it suffers from inherent security issues such as malicious participation and unfair contribution. The central server may become a bottleneck as well as induce biased aggregation and incentives. This article proposes a blockchain assisted federated learning framework, which fosters honest participation with reduced overheads, facilitating fair contribution-based weighted incentivization. A new consensus mechanism named PoIS (Proof of Interpretation and Selection) is proposed based on honest clients' contributions. PoIS uses model interpretation techniques for evaluating and calculating individual contributions. The aggregation of feature attributions in PoIS, is able to detect the adversaries, and the label-wise aggregation of attributions across the participants helps to define the prominent contributors. Further, we devise a credit function based on the contribution, relevance as well as the past performance for calculating incentives. Extensive experiments have been carried out for the proposed architecture with different settings, models, and datasets, to verify our claim. It successfully restricts the attack to less than 5%, and selects the prominent (top- ${k}$ ) contributors. Theoretical analysis provides the guarantee for byzantine-robust aggregation, in a malicious setting.