Machine-Checked Proofs of Privacy for Electronic Voting Protocols

Véronique Cortier (1, 2) , Catalin Dragan (1, 2) , François Dupressoir (3) , Benedikt Schmidt (4, 5) , Pierre-Yves Strub (6) , Bogdan Warinschi (7)

1 LORIA - Laboratoire Lorrain de Recherche en Informatique et ses Applications
2 PESTO - Proof techniques for security protocols
3 UNIS - University of Surrey
4 Institute IMDEA Software [Madrid]
5 Google Inc
6 LIX - Laboratoire d'informatique de l'École polytechnique [Palaiseau]
7 University of Bristol [Bristol]

We provide the first machine-checked proof of privacy-related properties (including ballot privacy) for an electronic voting protocol in the computational model. We target the popular Helios family of voting protocols, for which we identify appropriate levels of abstractions to allow the simplification and convenient reuse of proof steps across many variations of the voting scheme. The resulting framework enables machine-checked security proofs for several hundred variants of Helios and should serve as a stepping stone for the analysis of further variations of the scheme. In addition, we highlight some of the lessons learned regarding the gap between pen-and-paper and machine-checked proofs, and report on the experience with formalizing the security of protocols at this scale.

Domaines: Cryptographie et sécurité [cs.CR]

Véronique Cortier, Catalin Dragan, François Dupressoir, Benedikt Schmidt, Pierre-Yves Strub, et al.. Machine-Checked Proofs of Privacy for Electronic Voting Protocols. 38th IEEE Symposium on Security and Privacy (S&P'17), May 2017, San Jose, United States. pp.993 - 1008, ⟨10.1109/SP.2017.28⟩. ⟨hal-01624270⟩