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on ballots with just 11 to 17 questions. This likely allows a voter's votes to be known by anyone with the receipt. Moreover, even without a receipt, it leaks information that could discredit a voter's claimed candidate selections. Consequently, a voter conspiring to prove their vote (for money, coercion, or posterity) could mark all the ballots in a previously agreed unusual pattern that could later prove to a third party whether the agreement was kept (even without seeing the receipt). In either case, the veil of the secret ballot is pierced and traceable to the ID number on the receipt.
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for John and Barb above. Each of them has an "X", but the voter is actually voting for John and not Barb. Likewise if you saw just the second column ballot, it only shows a mark for Bill, but again the overall vote by the three ballots together is actually for John. When all 3 ballots are summed, the totals will show 2 marks for John and 1 mark each for Barb and Bill. Subtracting the number of voters, in this case 1, produces 1 vote for John and none for the others.
53:. ThreeBallot attempts to solve this problem by giving each voter three ballots: one verifiable, and two anonymous. The voter chooses which ballot is verifiable and keeps this secret; since the vote-counter does not know, there is a 1/3 chance of being discovered destroying or altering any single ballot. The voter is forced to make two of their three ballots cancel each other out, so that they can only vote once.
384:, each voter may verify that his votes were counted by searching for the identifier on his receipt amongst the published ballots. However, because the voter selects which of his ballots he receives as a receipt, he can arrange for his receipt to bear any combination of markings. Thus voters cannot prove to another party who they voted for, eliminating vote selling, coercion, etc. using this receipt.
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scheme, the proliferation of receipts (one per row) and chopped ballots rendered the mechanics of processing the votes or for a voter reviewing a receipt significantly complex, thus undermining its intended simplicity. An electronic version addressing the paper-ballot implementation and usability problems was proposed by Costa, et al.
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race can be rejected. Since there are exponentially more possible vote patterns than there are ballots cast in a typical precinct (or even people in the world), statistically most of the ballots cast can be trined uniquely for sufficiently long ballots. Typically, 90% of ballots can be reconstructed
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schema in his final publication to require tearing off each row (each yes/no) individually (destroying the correlation of the questions) and also having unique tracking numbers on each mark on each ballot (not just one ID for each column ballot). While this did restore the unbreakable aspect of the
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Typically, the ballots might be co-joined to simplify the marking by the voter, but before they are cast, it is imperative that the ballots be separated. Once separated and combined with other ballots in scrambled order, the true vote is encrypted. For example, consider just the third-column ballot
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At the polling station, the voter makes a copy of any one of his three ballots including its ID number. In practice, the machine verifying the ballots would perform this task automatically based on the voter's free choice of one of the ballots. Then, all three original ballots are dropped into the
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The encryption system used in the ThreeBallot was broken by a correlation attack devised by
Charlie Strauss, who also showed how it could be used to prove how you voted. While the ThreeBallot is secure if there is only one yes/no question on the ballot, Strauss observed that it is not secure when
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There is no indication on the ballots themselves which one was copied to make a receipt. Thus if at some point a ballot were "lost" or maliciously discarded, there is a 1/3 chance that this would be the receipt ballot. A vigilant voter could detect this loss.
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the candidate or not. While this also means that every candidate gets at least one vote when the three ballots are summed, this constant offset for all the candidates (equal to the number of voters) can be subtracted from the final total of all the ballots.
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Rivest discusses other benefits and flaws in his article. In particular, it is not suited for ranked preference voting. A field test has found ThreeBallot to have significant privacy, security, and usability problems, as well as implementation pitfalls.
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there are multiple questions, including the case of a single race with many candidates from which to choose. His attack exploited the fact that not every combination of 3 ballots forms a valid triple: proposed triples with 3 or 0 votes cast in
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vote once cast, so this multiple-vote fraud could not be detected until the final tally verification (and maybe not even then), and it cannot be corrected at that point or even traced to a specific voter.
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However, it is imperative to verify that the voter did not mismark their ballot – no candidate can be left blank on all 3 ballots, and no candidate can be selected on all three ballots:
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row on the ballot (not just one race of interest) can be rejected, since those ballots could not be from the same voter. Likewise, proposed trines resulting in a vote for more than one candidate in
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This requirement means all three ballots must be inserted into a machine to validate this before the 3-ballot vote is cast. Failure to do so would enable a voter to both cast an extra vote
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Each voter can verify that his vote was not discarded and was correctly used and not altered in the computation of the election result. (And if not, the voter is in a position to
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that can in principle be implemented on paper. The goal in its design was to provide some of the benefits of a cryptographic voting system without using cryptographic keys.
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A sample ThreeBallot multi-ballot, with a first race for
President with candidates Jones, Smith, and Wu and a second race for Senator with candidates Yip and Zinn.
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In the ThreeBallot voting system, voters are given three blank ballots, identical except for a unique identifier that is distinct for each ballot. To vote
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a candidate (the equivalent of leaving a ballot blank in other systems), the voter must select that candidate on
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Costa, R. G.; Santin, A. O.; Maziero, C. A. (2008). "A Three Ballot Based Secure
Electronic Voting System".
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Henry, K.; Stinson, D. R.; Sui, J. (2009). "The effectiveness of receipt-based attacks on threeballot".
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The ballots can be counted directly, without decryption. This is because they have the property that
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The crucial advantages that the ThreeBallot system offers over comparable, ciphered ballots are:
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and requires primarily low-tech devices, but is compatible with more advanced technologies.
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Thus every candidate gets at least one ballot with a mark and one ballot without a mark:
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a candidate, the voter must select that candidate on two of the three ballots. To vote
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and requires no additional security process beyond that afforded traditional ballots.
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Rivest later acknowledged this logic error in the original concept and revised the
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Everybody can verify that the election result was computed correctly.
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Each voter's vote is secret, preventing vote-selling and coercion.
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the sum of the marks is the sum of the votes for the candidate
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IEEE Transactions on
Information Forensics and Security
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ballot box. The voter keeps the one copy as a receipt.
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familiarly looking and simple for voters to understand
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Jones, Harvey; Jason Juang, and Greg Belote (2006). "
248:Any two columns marked indicates a "for" vote.
263:Any single column marked is not a "for" vote.
164:Additional theoretical system goals include:
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16:End-to-end auditable anonymous voting system
95:. Unsourced material may be challenged and
181:The method is designed for use with paper
147:no key that requires protection or secrecy
45:It may be difficult for a vote to be both
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505:", 6.857 class project, MIT. Reported in
115:Learn how and when to remove this message
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40:end-to-end (E2E) auditable voting system
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149:in order to maintain security (the "
93:adding citations to reliable sources
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578:"The Trouble with Triples Part 2"
528:"The Trouble with Triples Part 1"
30:is a voting protocol invented by
175:that the vote counters cheated.)
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459:"The ThreeBallot Voting System"
576:Charlie E. M. Strauss (2006).
526:Charlie E. M. Strauss (2006).
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153:" of many proposed systems).
38:in 2006. ThreeBallot is an
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503:Three Ballot in the Field
457:Ronald L. Rivest (2006).
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87:Please help
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204:exactly one
28:ThreeBallot
705:Categories
586:2015-04-16
536:2015-04-16
467:2007-01-16
439:References
337:Elle Error
105:April 2022
47:verifiable
32:Ron Rivest
716:Elections
669:CiteSeerX
320:Andy Oops
298:Candidate
215:Candidate
145:There is
76:does not
51:anonymous
646:10717380
427:See also
268:Bill Too
253:Barb Bar
237:John Foo
206:ballot.
691:5959774
366:against
358:against
200:against
183:ballots
97:removed
82:sources
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304:Notes
301:Ballot
221:Notes
218:Ballot
190:Method
687:S2CID
642:S2CID
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173:prove
57:Goals
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
