In order to make MACI secure we need to perform a multi-party trusted setup ceremony. @weijiekoh is helping us with that, but the ceremony requires an audit of MACI circuits and some social and technical coordination, so it will not happen soon (maybe only when we reach milestone 4 or later).
For our first production round we will do a simplified trusted setup, where the keys will be generated by a single person. This means we have to trust that person to destroy the secret parameters (“toxic waste”). I think this is acceptable risk because our current configuration requires a trusted owner, the contracts are not audited and the funding round will run on a sidechain. The amount of matching funds in our first production rounds should be limited in accordance with these risks.