Blockchain Audit

Before the emergence of blockchain technology, early explorations were undertaken to construct audit-based solutions\cite{belenkiy2008incentivizing}. These solutions relied on trusted clients to recompute sampled tasks performed by untrusted workers, employing incentive mechanisms to reward honest work and penalize cheating.

The advent of blockchain technology, notably underlying Bitcoin\cite{nakamoto2008bitcoin}, brought about revolutionary features such as immutability and traceability in decentralized data storage.

In the realm of federated learning, blockchain has been harnessed to ensure data provenance and maintain auditable blocks \cite{bao2019flchain, chen2018machine, li2020blockchain, qu2022blockchain}. This integration ensures the verification of learning processes, enabling validators to scrutinize results. Additionally, the incentive mechanisms inherent in blockchain ecosystems incentivize nodes to contribute high-quality data and services to decentralized systems.