Spectral-DP: Differentially Private Deep Learning through Spectral
  Perturbation and Filtering
Ce Feng Nuo Xu Wujie Wen Parv Venkitasubramaniam Caiwen Ding
Differential privacy is a widely accepted measure of privacy in the context
of deep learning algorithms, and achieving it relies on a noisy training
approach known as differentially private stochastic gradient descent (DP-SGD).
DP-SGD requires direct noise addition to every gradient in a dense neural
network, the privacy is achieved at a significant utility cost. In this work,
we present Spectral-DP, a new differentially private learning approach which
combines gradient perturbation in the spectral domain with spectral filtering
to achieve a desired privacy guarantee with a lower noise scale and thus better
utility. We develop differentially private deep learning methods based on
Spectral-DP for architectures that contain both convolution and fully connected
layers. In particular, for fully connected layers, we combine a block-circulant
based spatial restructuring with Spectral-DP to achieve better utility. Through
comprehensive experiments, we study and provide guidelines to implement
Spectral-DP deep learning on benchmark datasets. In comparison with
state-of-the-art DP-SGD based approaches, Spectral-DP is shown to have
uniformly better utility performance in both training from scratch and transfer
learning settings.