Cryptology ePrint Archive: Report 2013/216

Election Verifiability or Ballot Privacy: Do We Need to Choose?

Edouard Cuvelier and Olivier Pereira and Thomas Peters

Abstract: We propose a new encryption primitive, \emph{commitment consistent encryption} (CCE), and instances of this primitive that enable building the first universally verifiable voting schemes with a perfectly private audit trail (PPAT) and practical complexity. That is: \begin{myitemize} \item the audit trail that is published for verifying elections guarantees everlasting privacy, and \item the computational load required from the participants is only increased by a small constant factor compared to traditional voting schemes, and is optimal in the sense of Cramer, Gennaro and Schoenmakers~\cite{CGS97}. \end{myitemize} These properties make it possible to introduce election verifiability in large scale elections as a pure benefit, that is, without loss of privacy compared to a non-verifiable scheme and at a similar level of efficiency.

We propose different approaches for constructing voting schemes with PPAT from CCE, as well as two efficient CCE constructions: one is tailored for elections with a small number of candidates, while the second is suitable for elections with complex ballots.

Category / Keywords: public-key cryptography / electronic voting scheme, provable everlasting privacy

Date: received 12 Apr 2013

Contact author: thomas peters at uclouvain be

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Version: 20130414:154621 (All versions of this report)

Short URL: ia.cr/2013/216

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