Adapting Helios for Provable Ballot Privacy
Recent results show that the current implementation of Helios, a practical e-voting protocol, does not ensure independence of the cast votes, and demonstrate the impact of this lack of independence on vote privacy. Some simple fixes seem to be available and security of the revised scheme has been studied with respect to symbolic models.
In this paper we study the security of Helios using computational models. Our first contribution is a model for the property known as ballot privacy that generalizes and extends several existing ones.
Using this model, we investigate an abstract voting scheme (of which the revised Helios is an instantiation) built from an arbitrary encryption scheme with certain functional properties. We prove, generically, that whenever this encryption scheme falls in the class of voting-friendly schemes that we define, the resulting voting scheme provably satisfies ballot privacy.
We explain how our general result yields cryptographic security guarantees for the revised version of Helios (albeit from non-standard assumptions).
Furthermore, we show (by giving two distinct constructions) that it is possible to construct voting-friendly encryption, and therefore voting schemes, using only standard cryptographic tools.We detail an instantiation based on ElGamal encryption and Fiat-Shamir non-interactive zero-knowledge proofs that closely resembles Helios and which provably satisfies ballot privacy.
- Adapting Helios for Provable Ballot Privacy
- Book Title
- Computer Security – ESORICS 2011
- Book Subtitle
- 16th European Symposium on Research in Computer Security, Leuven, Belgium, September 12-14,2011. Proceedings
- pp 335-354
- Print ISBN
- Online ISBN
- Series Title
- Lecture Notes in Computer Science
- Series Volume
- Series ISSN
- Springer Berlin Heidelberg
- Copyright Holder
- Springer-Verlag GmbH Berlin Heidelberg
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- Editor Affiliations
- 16. MSIS Department and CIMIC, Rutgers University
- 17. K.U. Leuven ESAT-COSIC
- Author Affiliations
- 18. University of Bristol, England
- 19. LORIA - CNRS, France
- 20. Université Catholique de Louvain, Belgium
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