E-cclesia: Universally Composable Self-Tallying Elections

Abstract

The technological advancements of the digital era paved the way for the facilitation of electronic voting (e-voting) in the promise of efficiency and enhanced security. In standard e-voting designs, the tally process is assigned to a committee of designated entities called talliers. Naturally, the security analysis of any e-voting system with tallier designation hinges on the assumption that a subset of the talliers follows the execution guidelines and does not attempt to breach privacy. As an alternative approach, Kiayias and Yung [PKC ’02] pioneered the self-tallying elections (STE) paradigm, where the post-ballot-casting (tally) phase can be performed by any interested party, removing the need for tallier designation. In this work, we explore the prospect of decentralized e-voting where security is preserved under concurrent protocol executions. In particular, we provide the first comprehensive formalization of STE in the universal composability (UC) framework introduced by Canetti [FOCS ’01] via an ideal functionality that captures required security properties such as voter privacy, eligibility, fairness, one-voter one-vote, and verifiability. We provide a concrete instantiation, called E-cclesia , that UC realizes our functionality. The design of E-cclesia integrates several cryptographic primitives such as signatures of knowledge for anonymous eligibility check, dynamic accumulators for scalability, time-lock encryption for fairness and anonymous broadcast channels for voter privacy. For the latter primitive, we provide the first UC formalization along with a construction based on mix-nets that utilises layered encryption, threshold secret sharing and equivocation techniques. Finally, we discuss deployment and scalability considerations for E-cclesia . We present preliminary benchmarks of the key operations (in terms of computational cost) of the voting client and demonstrate the feasibility of our proposal with readily available cryptographic tools for mid-sized elections (∼100,000 voters).

Available format(s)
Category
Cryptographic protocols
Publication info
Preprint.
Keywords
e-voting anonymous broadcast universally composable security
Contact author(s)
marapini @ inf ed ac uk
nikolaoslabrou @ yahoo gr
lenka marekova 2018 @ rhul ac uk
tzachari @ inf ed ac uk
leo ackermann @ ens-rennes fr
pavlos1998 @ gmail com
History
2022-12-01: last of 4 revisions
See all versions
Short URL
https://ia.cr/2020/513

CC BY

BibTeX

@misc{cryptoeprint:2020/513,
author = {Myrto Arapinis and Nikolaos Lamprou and Lenka Mareková and Thomas Zacharias and Léo Ackermann and Pavlos Georgiou},
title = {E-cclesia: Universally Composable Self-Tallying Elections},
howpublished = {Cryptology ePrint Archive, Paper 2020/513},
year = {2020},
note = {\url{https://eprint.iacr.org/2020/513}},
url = {https://eprint.iacr.org/2020/513}
}

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