DictPFL: Efficient and Private Federated Learning on Encrypted Gradients

Fuente: arXiv
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Hauptverfasser: Xue, Jiaqi, Kumar, Mayank, Shang, Yuzhang, Gao, Shangqian, Ning, Rui, Zheng, Mengxin, Jiang, Xiaoqian, Lou, Qian
Format: Preprint
Veröffentlicht: 2025
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author Xue, Jiaqi
Kumar, Mayank
Shang, Yuzhang
Gao, Shangqian
Ning, Rui
Zheng, Mengxin
Jiang, Xiaoqian
Lou, Qian
author_facet Xue, Jiaqi
Kumar, Mayank
Shang, Yuzhang
Gao, Shangqian
Ning, Rui
Zheng, Mengxin
Jiang, Xiaoqian
Lou, Qian
contents Federated Learning (FL) enables collaborative model training across institutions without sharing raw data. However, gradient sharing still risks privacy leakage, such as gradient inversion attacks. Homomorphic Encryption (HE) can secure aggregation but often incurs prohibitive computational and communication overhead. Existing HE-based FL methods sit at two extremes: encrypting all gradients for full privacy at high cost, or partially encrypting gradients to save resources while exposing vulnerabilities. We present DictPFL, a practical framework that achieves full gradient protection with minimal overhead. DictPFL encrypts every transmitted gradient while keeping non-transmitted parameters local, preserving privacy without heavy computation. It introduces two key modules: Decompose-for-Partial-Encrypt (DePE), which decomposes model weights into a static dictionary and an updatable lookup table, only the latter is encrypted and aggregated, while the static dictionary remains local and requires neither sharing nor encryption; and Prune-for-Minimum-Encrypt (PrME), which applies encryption-aware pruning to minimize encrypted parameters via consistent, history-guided masks. Experiments show that DictPFL reduces communication cost by 402-748$\times$ and accelerates training by 28-65$\times$ compared to fully encrypted FL, while outperforming state-of-the-art selective encryption methods by 51-155$\times$ in overhead and 4-19$\times$ in speed. Remarkably, DictPFL's runtime is within 2$\times$ of plaintext FL, demonstrating for the first time, that HE-based private federated learning is practical for real-world deployment. The code is publicly available at https://github.com/UCF-ML-Research/DictPFL.
format Preprint
id arxiv_https___arxiv_org_abs_2510_21086
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle DictPFL: Efficient and Private Federated Learning on Encrypted Gradients
Xue, Jiaqi
Kumar, Mayank
Shang, Yuzhang
Gao, Shangqian
Ning, Rui
Zheng, Mengxin
Jiang, Xiaoqian
Lou, Qian
Machine Learning
Cryptography and Security
Federated Learning (FL) enables collaborative model training across institutions without sharing raw data. However, gradient sharing still risks privacy leakage, such as gradient inversion attacks. Homomorphic Encryption (HE) can secure aggregation but often incurs prohibitive computational and communication overhead. Existing HE-based FL methods sit at two extremes: encrypting all gradients for full privacy at high cost, or partially encrypting gradients to save resources while exposing vulnerabilities. We present DictPFL, a practical framework that achieves full gradient protection with minimal overhead. DictPFL encrypts every transmitted gradient while keeping non-transmitted parameters local, preserving privacy without heavy computation. It introduces two key modules: Decompose-for-Partial-Encrypt (DePE), which decomposes model weights into a static dictionary and an updatable lookup table, only the latter is encrypted and aggregated, while the static dictionary remains local and requires neither sharing nor encryption; and Prune-for-Minimum-Encrypt (PrME), which applies encryption-aware pruning to minimize encrypted parameters via consistent, history-guided masks. Experiments show that DictPFL reduces communication cost by 402-748$\times$ and accelerates training by 28-65$\times$ compared to fully encrypted FL, while outperforming state-of-the-art selective encryption methods by 51-155$\times$ in overhead and 4-19$\times$ in speed. Remarkably, DictPFL's runtime is within 2$\times$ of plaintext FL, demonstrating for the first time, that HE-based private federated learning is practical for real-world deployment. The code is publicly available at https://github.com/UCF-ML-Research/DictPFL.
title DictPFL: Efficient and Private Federated Learning on Encrypted Gradients
topic Machine Learning
Cryptography and Security
url https://arxiv.org/abs/2510.21086