What is chain voting?

Question

I read The Three Ballot Voting System by Rivest. This paper-based voting system can be attacked with chain voting. But can't find any description of what "Chain voting" is mentioned in section 4.9.

Would anyone explain what it is?

Answer 1

After a small search; it is a vote buying scheme.

Chain voting, a vote buying scheme in which a crook gives the voter a pre-voted ballot, the voter votes that ballot, and then after leaving the polling place, sells his blank ballot to the crook, who votes it and then gives it to the next willing participant.

This is from Douglas W. Jones web page and reference 12 of the Rivest's article points his definition.

This attack is applied in many countries (I'll not give any source). One countermeasure can be paper-based PUF. Also, some ideas from University Voting Systems Competition might be interesting to look at.

Answer 2

The MGM Crime Does Not Pay subject "You, the People" (1940) depicts chain voting (among many other election-fraud techniques) organized by the political machine of a fictional big city:

INT. BASEMENT. Two men sit at a long table covered in papers. A middle-aged voter enters with something under his coat.

MAN AT TABLE: All right, let's have it. [The voter hands over a folded sheet of paper, which the man unfolds.] Okay.

CLOSE-UP on the paper. It's a ballot. The man at the table marks the ballot with an X for the Machine's candidate in each race, and re-folds it in quarters.

Meanwhile, the first voter has departed and another voter, an elderly, dissipated-looking man in a battered hat, has entered. He presents a card to the men at the table; they inspect it and nod.

MAN AT TABLE: You ever vote a chain ballot before? Well, it's just so you can't cheat us. This ballot's already marked. The only way you can get your two bucks is to vote it and bring us back the clean one they give you so we can mark it for the next guy. Now don't crumple it.

OTHER MAN AT TABLE [having consulted a large box of cards and drawn one]: Registration receipt. Use that name and address, and step on it.

Battered Hat puts the marked ballot under his coat and departs.