What is the first zero-knowledge proof used to prevent cheating in e-voting?

Conditions

• There are two candidate slots in the example.
• Each slot contains one encrypted value.
• The proof must hold without revealing the individual values.

Reasoning, step by step

1. Identify the election rule: each voter must choose exactly one candidate, neither both nor none.
2. Formulate the first zero-knowledge proof required by the protocol: the encrypted values in a ballot sum to 1.
3. Verify that the sum of the encrypted vote values equals 1.
4. Ensure the proof holds without revealing the individual values.

Example

The speaker states that the first zero-knowledge proof is that the sum of the things inside your envelope sums up to one, meaning you voted for exactly one candidate.

Common misconceptions

• Mistaking sum-to-one for full ballot validity: If the encrypted votes sum to 1, the ballot must be valid, whereas non-binary values can satisfy the same equation.

Watch the explanation

Explore next

• Why is proving only that the votes sum to one not enough?
• What does the second zero-knowledge proof check in the voting protocol?