Machine learning is vulnerable to adversarial examples: inputs carefully
modified to force misclassification. Designing defenses against such inputs
remains largely an open problem. In this work, we revisit defensive
distillation---which is one of the mechanisms proposed to mitigate adversarial
examples---to address its limitations. We view our results not only as an
effective way of addressing some of the recently discovered attacks but also as
reinforcing the importance of improved training techniques.