Cryptology ePrint Archive: Report 2020/1332

Protecting the Privacy of Voters: New Definitions of Ballot Secrecy for E-Voting

Ashley Fraser and Elizabeth A. Quaglia

Abstract: Protecting the privacy of voters is a basic requirement of any electronic voting scheme, and formal definitions can be used to prove that a scheme satisfies privacy. In this work, we provide new game-based definitions of ballot secrecy for electronic voting schemes. First, we propose an intuitive definition in the honest model, i.e., a model in which all election officials are honest. Then, we show that this definition can be easily extended to the malicious ballot box setting and a setting that allows for a distributed tallier. In fact, to the best of our knowledge, we provide the first game-based definition of ballot secrecy that models both a malicious ballot box and a malicious subset of talliers. We demonstrate that our definitions of ballot secrecy are satisfiable, defining electronic voting scheme constructions which we prove satisfy our definitions. Finally, we revisit existing definitions, exploring their limitations and contextualising our contributions to the field.

Category / Keywords: public-key cryptography / E-voting, ballot secrecy, game-based definitions

Original Publication (in the same form): Selected Areas in Cryptography (SAC) 2020

Date: received 23 Oct 2020

Contact author: Ashley Fraser 2016 at live rhul ac uk

Available format(s): PDF | BibTeX Citation

Version: 20201026:092212 (All versions of this report)

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