OpenVoting: Making E2E-V voting transparent and recoverable

End-to-end verifiable (E2E-V) voting systems have been around for some time. However, their adoption in large elections is poor, seemingly because of the inaccessibility of their underlying complex cryptography to the general electorate. Meanwhile, risk-limiting audits based on voter-verified paper records (VVPR) have been effective in bringing easy-to-understand verifiability and recoverability to electronic voting, but they generally require the electorate to trust the post-election custody chain of the paper trail. In this paper, we propose \emph{OpenVoting}, a novel polling booth voting protocol that publicly demonstrates a one-to-one correspondence between the cryptographically-secured electronic vote records and the easily understandable paper records, while protecting individual voter secrecy and polling booth-level voting statistics. This one-to-one correspondence helps each provide a check for the other, improves overall transparency, and also enables efficient and principled recovery in case of tally mismatches, by pinpointing mismatching votes and their associated polling booths. We propose a novel distributed zero-knowledge proof (ZKP) that facilitates the above. To an ordinary voter \emph{OpenVoting} looks just like an old fashioned paper based voting system, with minimal additional cognitive overload.