TAPFed: Threshold Secure Aggregation for Privacy-Preserving Federated Learning
Malicious aggregators in multi-party federated learning pose severe gradient leakage and privacy risks. Method: This paper introduces Threshold Fully Homomorphic Encryption (TFHE) into secure aggregation for the first time, proposing a decentralized privacy-preserving training framework tolerant to a bounded number of malicious aggregators. It eliminates reliance on trusted third parties by integrating secure multi-party computation with formal verification, effectively countering novel disaggregation attacks. Contribution/Results: We provide rigorous theoretical proofs establishing strict differential privacy and collusion resistance. Empirical evaluation demonstrates that the framework maintains state-of-the-art model accuracy while reducing communication overhead by 29–45%, and delivers end-to-end privacy guarantees under diverse strong adversarial models, including active and adaptive adversaries.