This is a blog by Ian Goodfellow and Nicolas Papernot about security and privacy in machine learning. Ian is a research scientist at OpenAI, and Nicolas a Google PhD Fellow in Security at Penn State. We jointly created cleverhans, an open-source library for benchmarking the vulnerability of machine learning models to adversarial examples. The blog gives us a way to informally share ideas about machine learning security and privacy that are not yet concrete enough for traditional academic publishing, and to share news and updates relevant to the cleverhans library.