Paper 2021/397

SSProve: A Foundational Framework for Modular Cryptographic Proofs in Coq

Carmine Abate and Philipp G. Haselwarter and Exequiel Rivas and Antoine Van Muylder and Théo Winterhalter and Catalin Hritcu and Kenji Maillard and Bas Spitters

Abstract

State-separating proofs (SSP) is a recent methodology for structuring game-based cryptographic proofs in a modular way. While very promising, this methodology was previously not fully formalized and came with little tool support. We address this by introducing SSProve, the first general verification framework for machine-checked state-separating proofs. SSProve combines high-level modular proofs about composed protocols, as proposed in SSP, with a probabilistic relational program logic for formalizing the lower-level details, which together enable constructing fully machine-checked crypto proofs in the Coq proof assistant. Moreover, SSProve is itself formalized in Coq, including the algebraic laws of SSP, the soundness of the program logic, and the connection between these two verification styles.