Cast-as-Intended: A Formal Definition and Case Studies

This paper allows analysts to verify cast-as-intended, i.e., whether a digital ballot captures a voter's intent

Peter B. Rønne, Peter Y. A. Ryan & Ben Smyth (2021) Cast-as-Intended: A Formal Definition and Case Studies. In FC'21: 25th International Conference on Financial Cryptography and Data Security (LNCS), 251–262, Springer.

Abstract

Verifiable voting systems allow voters to check whether their ballot is correctly recorded (individual verifiability) and allow anyone to check whether votes expressed in recorded ballots are correctly counted (universal verifiability). This suffices to ensure that honest voters' votes are correctly counted, assuming ballots are properly generated. Achieving ballot assurance, i.e., assuring each voter that their vote is correctly encoded inside their ballot, whilst ensuring privacy, is a challenging aspect of voting system design. This assurance property is known as cast-as-intended. Unlike many properties of voting systems, it has yet to be formalised. We provide the first formal definition and apply our definition to MarkPledge, Pret a Voter, Selene, ThreeBallot, and schemes based upon Benaloh challenges.

$ curl -s https://publications.bensmyth.com/files/Smyth21-cast-as-intended.bib | cat
@inproceedings{Smyth21-cast-as-intended,
  title = {{Cast-as-Intended:}}
        # {{ A Formal Definition and Case Studies}},
  year = {2021}, author = {Peter B. Rønne and Peter Y. A. Ryan and Ben Smyth}, doi = {10.1007/978-3-662-63958-0\_22},
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  url-pdf = {./files/cast-as-intended.pdf},
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