MACI

Minimal Anti-Collusion Infrastructure (MACI)

Vitalik's high-profile concern on the shortcomings of voting systems, both traditional and digital, has helped drive interest in cryptography-native mechanisms. A zero-knowledge based system titled Minimum Anti-Collusion Infrastructure (MACI) was created in this blog post and serves as the basis for this mechanism.

“MACI is an Ethereum application that provides privacy and collusion resistance for on-chain voting, both in a quadratic and non-quadratic fashion. A common problem among today’s on-chain voting (or public good funding) processes is how easy it is to bribe voters into voting for a particular option. MACI [uses] encryption and zero-knowledge proofs (zk-SNARKs) to hide how each person voted while still publicly revealing the final result.” - Welcome to MACI

MACI works as a modification to a typical QF round. Some mechanisms previously used to help shape incentives hold reduced relevance, and new mechanisms exist to deliver unique opportunities to communities.

Allow List

A round’s allowlist is a feature that gives advantage to certain participants, known as allowlisted members. This can be based on badgeholding, verifiable event attendance, or some other property.

Maximum round contribution limits can be set for the general public and allowlist users separately. This can mean raised donation limits for the allowlist - or in the case of a $0 limit for the general public, complete exclusivity in participation.

Differences to Conventional QF

A matching cap is typically employed by a QF round to ensure one grantee is not afforded too large a share of the matching pool. In MACI it is not technically feasible to implement this. However, with low contribution limits, it becomes more difficult for a single project to receive a large portion of the matching pool.

The post-round analytics common to a conventional QF round are also challenged by MACI - only the coordinator can tally the votes, prove the correctness of the results, and publish the results.

Round Coordinator

The round coordinator may be an individual or an organization, and exists as the only point of trust in the entire round process. Using a generated private key the round coordinator creates zk-proofs verifiable on-chain. The coordinator can decrypt the MACI-private donations (votes), but not modify or remove them.

Donations/Voting

When a round is live, participants can add projects to their cart following the typical Grants Stack flow. A donation can only be made once per round, after which the donor will receive spendable votes proportional to their contribution. These can be distributed among as many projects as desired, and can be changed later.

Ending a round

At the conclusion of the round, the coordinator will be responsible for tallying the results and proving their correctness using zk-SNARK technology.