The Cryptol specification language was designed by Galois for the NSA's Trusted Systems Research Group as a public standard for specifying cryptographic algorithms. A Cryptol reference specification can serve as the formal documentation for a cryptographic module. Unlike current specification mechanisms, Cryptol is fully executable, allowing designers to experiment with their programs incrementally as their designs evolve. This release is an interpreter for version 2 of the Cryptol language. The interpreter includes a :check command, which tests predicates written in Cryptol against randomly-generated test vectors (in the style of QuickCheck). There is also a :prove command, which calls out to SMT solvers, such as Yices, Z3, or CVC4, to prove predicates for all possible inputs.