A shared vault for shielded Zcash. A group controls one shielded address, and a payment goes out only when t of the N members approve it on their phones.
- Private on chain: re-randomized FROST makes one ordinary spend signature, so a vault looks like any single-user wallet.
- No blind signing: every phone rebuilds and checks the transaction before it signs.
- Blind relay: the server only forwards encrypted messages and can't spend.