We generalize the aforementioned definition of correctness to account for a malicious bulletin board (full correctness) and we provide a generic construction that transforms a correct voting scheme into a fully correct voting scheme. This construction simply requires to send credentials to the voters, with no additional infrastructure. We further provide a simple and natural criteria that implies voting correctness, which can then be turned into full correctness due to our construction. As an application, we build a variant of Helios that is both fully correct, verifiable and private.
Real-world elections often require threshold cryptosystems so that any t out of l trustees can proceed to tallying. We describe a fully distributed (with no dealer) threshold cryptosystem suitable for Helios (in particular, suitable to partial decryption). In doing so we happen to revisit the seminal multi-authority election system from Cramer, Gennaro and Schoenmakers. Altogether, we provide the first proof of privacy, verifiability and correctness for a fully distributed Helios voting scheme (and its enhanced version with credentials), together with its detailed description. This also implies, to our knowledge, the first formal proofs of privacy, verifiability and correctness for the scheme by Cramer et al. Last but not least, we provide an open source implementation of our variant of Helios.Category / Keywords: cryptographic protocols / voting protocols, Helios, correctness, full correctness, verifiability, ballot privacy, fully distributed threshold cryptosystem, implementation Publication Info: In submission Date: received 28 Mar 2013, last revised 21 May 2013 Contact author: david galindo-chacon at loria fr Available format(s): PDF | BibTeX Citation Version: 20130521:145727 (All versions of this report) Short URL: ia.cr/2013/177 Discussion forum: Show discussion | Start new discussion