The ThreeBallot voting system was invented by Ron Rivest as an end-to-end auditable system where each voter casts three paper ballots with certain restrictions on how they can be filled out. It aims to make votes anonymous yet verifiable by allowing each voter to verify their vote was counted correctly and nobody's vote was discarded or altered, while also allowing anybody to verify the election result and voter list. Voters fill out three ballots with rules like not leaving rows blank or filling all circles in a row.

1. ThreeBallot
end-to-end (E2E) auditable voting system

2. Main info
Invented by Ron Rivest, co-author of RSA,
RC4/RC5 (Rivest Cipher) and MD5.
Published in October 2006 at MIT
Each voter casts three paper ballots, with
certain restrictions on how they may be filled
out

3. Problem
Vote should be at same time
anonymous and verifiable.

4. Goals
1. Each voter's vote is secret, preventing vote-selling and
coercion.
2. Each voter can verify that his vote was not discarded,
and was correctly used and not altered, in the computation
of the election result.
3. Everybody can verify the election result was computed
correctly.
4. Everybody can verify that extra fake "voters" were not
added, and the full list of voters is publicly known.

5. Ballot

6. Voting rules
1. You can't leave row unfilled
2. You can't fill all three circle in the row
3. For candidate - two circles in row
4. Against candidate - at least on circle in row
5. For vote - at most one candidate per race
6. You may vote against all candidates
7. Voter makes copy on of the ballot with
unique identifier at the bottom

7. Voting fraud
1. Adding ballots
2. Modifying ballots
3. Vote selling
4. Three pattern attack
5. Take photos of ballot

8. Other voting system
1. Plurality voting
2. Approval voting
3. Range voting
4. Vote-antivote-vote
5. Twin
6. Punchscan

9. Links
1. http://people.csail.mit.edu/rivest/Rivest-
TheThreeBallotVotingSystem.pdf
2. http://www.cs.princeton.
edu/~appel/papers/DefeatingThreeBallot.pdf
3. http://en.wikipedia.org/wiki/ThreeBallot