Ballot secrecy and ballot independence: definitions and relations

This paper presents a formal definition of ballot independence as a cryptographic game and proves that ballot secrecy implies ballot independence.

Ben Smyth & David Bernhard (2014) Ballot secrecy and ballot independence: definitions and relations. Technical Report 2013/235, Cryptology ePrint Archive.

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.

$ curl -s https://publications.bensmyth.com/files/Smyth14-ballot-independence-for-election-schemes.bib | cat
@techreport{Smyth14-ballot-independence-for-election-schemes,
  title = {{Ballot secrecy and ballot independence:}}
        # {{ definitions and relations}},
  year = {2014}, author = {Ben Smyth and David Bernhard},
  url = {./},
  url-pdf = {./files/ballot-independence.pdf},
  url-bib = {./files/ballot-independence-for-election-schemes.bib},
  url-yaml = {./files/ballot-independence-for-election-schemes.yml},
  url-md = {./files/ballot-independence.md}
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