Halo 2 is the name of both a leading-edge zk-SNARK theory and its implementation. It was developed by the team behind Electric Coin Co., the inventors of Zcash. Halo 2 is a successor to Halo, and both systems are inspired partly by the zk-SNARK theories PLONK and Sonic, among others.
Orbis Labs chose Halo 2 as the basis for our zk-SNARK implementations due to the following considerations. In no particular order:
- Relatively stable and mature. It is audited, production ready, and used at scale in production.
- Efficient proving algorithm.
- Relatively small proofs which are not very computationally difficult to verify.
- Rich ecosystem of tooling, SDKs, and reusable circuit code.
- Does not require a trusted setup process and has no trust assumptions. Verifiers need not trust provers or any third party.