Doubly Robust Instance-Reweighted Adversarial Training
Daouda Sow Sen Lin Zhangyang Wang Yingbin Liang
Assigning importance weights to adversarial data has achieved great success
in training adversarially robust networks under limited model capacity.
However, existing instance-reweighted adversarial training (AT) methods heavily
depend on heuristics and/or geometric interpretations to determine those
importance weights, making these algorithms lack rigorous theoretical
justification/guarantee. Moreover, recent research has shown that adversarial
training suffers from a severe non-uniform robust performance across the
training distribution, e.g., data points belonging to some classes can be much
more vulnerable to adversarial attacks than others. To address both issues, in
this paper, we propose a novel doubly-robust instance reweighted AT framework,
which allows to obtain the importance weights via exploring distributionally
robust optimization (DRO) techniques, and at the same time boosts the
robustness on the most vulnerable examples. In particular, our importance
weights are obtained by optimizing the KL-divergence regularized loss function,
which allows us to devise new algorithms with a theoretical convergence
guarantee. Experiments on standard classification datasets demonstrate that our
proposed approach outperforms related state-of-the-art baseline methods in
terms of average robust performance, and at the same time improves the
robustness against attacks on the weakest data points. Codes will be available
soon.