We just did a fully trustless shielded ZEC to EVM atomic swap with no new signing primitives! And yes, it is programmable

[strahncryptography]

I hope this is not too crude, best I could do with Mermaid. This is for the new P2P flow, ETH->ZEC.

For ZEC->ETH, the flow is more or less the same for P2P, just with the roles reversed.

Specifically, a spending key is never needed for party B before execution, and they have to reveal rho, rcm, psi and nullifier for now, which will be hidden by NIZK later.