key: 2014-ballot-independence-for-election-schemes
type: techreport
title: "Ballot secrecy and ballot independence: definitions and relations"
authors:
  - Ben Smyth
  - David Bernhard
year: 2014
month: 10
number: 2013/235
institution: Cryptology ePrint Archive
description: >-
  This paper presents a formal definition of ballot independence as a cryptographic game and proves
  that ballot secrecy implies ballot independence.
keywords: >-
  ballot independence, ballot secrecy, elections, election schemes, electronic voting, e-voting,
  Helios, controlled malleability, malleability
abstract: >-
  We study ballot independence for election schemes. First, we formally define ballot independence
  as a cryptographic game and prove that ballot secrecy implies ballot independence. Secondly, we
  introduce a notion of controlled malleability and prove that it is sufficient for ballot
  independence. We also prove that non-malleable ballots are sufficient for ballot independence.
  Thirdly, we prove that ballot independence is sufficient for ballot secrecy in a special case. Our
  results show that ballot independence is necessary in election schemes satisfying ballot secrecy.
  Furthermore, our sufficient conditions enable simpler proofs of ballot secrecy.
supersededby:
  - key: 2015-ballot-secrecy
    text: extension
links:
  - file: Smyth14-ballot-independence.pdf
    text: Draft
    alt:
      url: https://eprint.iacr.org/2013/235
      text: Cryptology ePrint Archive version