Surveying definitions of coercion resistance

This manuscript explores definitions of coercion resistance in the computational model; discovering all but one are unsuitable.

Thomas Haines & Ben Smyth (2020) Surveying definitions of coercion resistance. Technical Report 2019/822, Cryptology ePrint Archive.

Abstract

We explore formal definitions of coercion resistance (WPES'05, FC'09, CRYPTO'10, and CSF'10), conceived to capture the strongest privacy notions achievable by voting systems. We find all but one is unsuitable, demonstrating difficulties faced by our community in formalising this property and raising questions over the security of schemes striving to deliver coercion resistance. We find the remaining definition to be reliant on burdensome combinatorial analysis, prohibiting immediate application. We propose a variant that simplifies application. We also patch an unsuitable definition and introduce sufficient conditions to simplify proofs.

$ curl -s https://publications.bensmyth.com/files/Smyth19-surveying-coercion-resistance.bib | cat
@techreport{Smyth19-surveying-coercion-resistance,
  title = {{Surveying definitions of coercion resistance}},
  year = {2020}, author = {Thomas Haines and Ben Smyth},
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  url-pdf = {./files/surveying-coercion-resistance.pdf},
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  url-yaml = {./files/surveying-coercion-resistance.yml}
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