Abstract. We present EasyCrypt, an automated tool for elaborating security proofs of cryptographic systems from proof sketches—compact, formal representations of the essence of a proof as a sequence of games and hints. Proof sketches are checked automatically using off-the-shelf SMT solvers and automated theorem provers, and then compiled into verifiable proofs in the CertiCrypt framework. The tool supports most common reasoning patterns and is significantly easier to use than its predecessors. We argue that EasyCrypt is a plausible candidate for adoption by working cryptographers and illustrate its application to security proofs of the Cramer-Shoup and Hashed ElGamal cryptosystems.
Keywords: Provable security, verifiable security, game-based proofs, Cramer-Shoup cryptosystem, ElGamal encryption.