Democracy demands the integrity of our elections: if we cannot trust the votes, how can we trust our government?
Election security is a difficult and complex problem, and one in which we must sacrifice some security to gain other security, such as by allowing mail-in absentee ballots to avoid disenfranchisement. Fair representation also tends to require more-complex voting rules, necessitating strict security and transparency procedures.
Our election system brings with it a variety of concerns, some the result of trade-offs.
Voter Disenfranchisement may occur if a voter cannot reach the polls. We assign polling places to voters to avoid voter fraud: a voter presents at the assigned polling place, declares their name, and is announced loudly. The polling place, being close to their neighborhood, will likely contain neighbors and others who may recognize the voter, and will recognize an impostor; likewise, the real voter may attempt to vote, causing conflict and alerting the election judge.
In general, a voter may only use the assigned polling place, preventing impostor voting or repeat voting. To combat disenfranchisement, we allow early voting and mail-in ballots. This weakens the strength of the assigned polling place defense, but still prevents double-voting due to the election board associating names with ballots. Ballots are anonymous because these names are not published.
Mail-in ballots can be proven by allowing a third party to observe the voter, thus opening the election system to voter coercion and vote buying. Although postal voting opens up an additional tampering concern, we trust election judges. Delivering and opening ballots in the presence of observers does not fully protect against tampering: voter lists reveal historical party votes cast by individuals, and the return address on an envelope can predict the party a ballot will likely support, so operatives along the way can tamper.
We accept these concerns because they represent a subset of ballots, thus are diminished in scope; and because voter disenfranchisement and vote tampering are similar attacks, and disenfranchisement is certain while tampering is only ever partially effective. Tampering with mail-in ballots is extremely difficult, even if theoretically-possible, due to the need for broad collusion.
Security with Modernized Voting
Modernized voting requires strict security procedures. Even simple population growth has increased the number of ballots counted and the difficulty in summing the counts, changing our security concerns. Ranked ballots, complex voting methods, and computerized counting raise additional concerns.