PPFL: Privacy-Preserving Techniques in Federated Learning
Khalil Jahani, Behzad Moshiri, Babak Hossein Khalaj · Journal of Artificial Intelligence Applications and Innovations · 2024
Federated Learning is a distributed machine learning paradigm designed to preserve user privacy on decentralized devices without transferring raw data to a central server. Protecting data privacy in FL involves determining permissible operations and how they can be executed. This review provides an in-depth exploration of privacy threat models within FL, distinguishing between scenarios where the central server is either trusted or untrusted, and identifying appropriate defensive tools and technologies for these settings. The review covers secure computational techniques, including MPC, HE, and TEEs, as well as privacy-preserving mechanisms such as DP, LDP, and DDP models. It also examines hybrid approaches that combine multiple privacy models to enhance efficiency and robustness. The effectiveness of these methods is analysed across different scenarios involving both honest and potentially malicious servers and users. The findings reveal that while privacy-preserving methods mitigate risks, challenges persist in trade off privacy, communication efficiency, and model accuracy. This review highlights open research directions and serves as a comprehensive reference for researchers and practitioners seeking to implement robust privacy measures in federated learning systems.