# Secure Federated Matrix Factorization

## TL;DR

This paper introduces FedMF, a federated matrix factorization framework that enhances user privacy through homomorphic encryption, enabling secure model training without raw data sharing, and demonstrates its feasibility with real data.

## Contribution

We propose FedMF, a novel federated matrix factorization method that incorporates homomorphic encryption to protect user data during distributed learning.

## Key findings

- FedMF is feasible with real-world datasets.
- Gradient information can leak raw user data.
- Homomorphic encryption enhances privacy in federated matrix factorization.

## Abstract

To protect user privacy and meet law regulations, federated (machine) learning is obtaining vast interests in recent years. The key principle of federated learning is training a machine learning model without needing to know each user's personal raw private data. In this paper, we propose a secure matrix factorization framework under the federated learning setting, called FedMF. First, we design a user-level distributed matrix factorization framework where the model can be learned when each user only uploads the gradient information (instead of the raw preference data) to the server. While gradient information seems secure, we prove that it could still leak users' raw data. To this end, we enhance the distributed matrix factorization framework with homomorphic encryption. We implement the prototype of FedMF and test it with a real movie rating dataset. Results verify the feasibility of FedMF. We also discuss the challenges for applying FedMF in practice for future research.