\texttt{cleverhans} is a software library that provides standardized reference implementations of \emph{adversarial example} construction techniques and \emph{adversarial training}. The library may be used to develop more robust machine learning models and to provide standardized benchmarks of models' performance in the adversarial setting. Benchmarks constructed without a standardized implementation of adversarial example construction are not comparable to each other, because a good result may indicate a robust model or it may merely indicate a weak implementation of the adversarial example construction procedure. This technical report is structured as follows. Section~\ref{sec:introduction} provides an overview of adversarial examples in machine learning and of the \texttt{cleverhans} software. Section~\ref{sec:core} presents the core functionalities of the library: namely the attacks based on adversarial examples and defenses to improve the robustness of machine learning models to these attacks. Section~\ref{sec:benchmark} describes how to report benchmark results using the library. Section~\ref{sec:version} describes the versioning system.