Reflection, Rewinding, and Coin-Toss in EasyCrypt

Reflection, Rewinding, and Coin-Toss in EasyCrypt (CPP 2022)
Denis Firsov, Dominique Unruh
[ eprint | official ]

In this paper we derive a suite of lemmas which allows users to internally reflect EasyCrypt programs into distributions which correspond to their denotational semantics (probabilistic reflection). Based on this we develop techniques for reasoning about rewinding of adversaries in EasyCrypt. (A widely used technique in cryptology.) We use our reflection and rewindability results to prove the security of a coin-toss protocol.