Privacy and Data Reconstruction in Low-Rank Personalized Federated Learning
Motivation Federated learning enables multiple clients to train models collaboratively without sharing raw data. When each participating centre aims to obtain its own personalised model rather than a single global model, the field is referred to as personalised federated learning (pFL). Although data is never transmitted directly, research has shown that gradients and model updates can still leak sensitive information, enabling partial reconstruction of private training data. Recent approaches based on low-rank matrix factorisation promise communication efficiency and improved personalisation. However, it remains unclear whether such structured parameterisations strengthen or weaken privacy protection. ...