Privatized graph federated learning

Federated learning is a semi-distributed algorithm, where a server communicates with multiple dispersed clients to learn a global model. The federated architecture is not robust and is sensitive to communication and computational overloads due to its one-master multi-client structure. It can also be subject to privacy attacks targeting personal information on the communication links. In this work, we introduce graph federated learning, which consists of multiple federated units connected by a graph. We then show how graph-homomorphic perturbations can be used to ensure the algorithm is differentially private on the server level. While on the client level, we show that improvement in the differentially private federated learning algorithm can be attained through the addition of random noise to the updates, as opposed to the models. We conduct both convergence and privacy theoretical analyses and illustrate performance by means of computer simulations.