Core flows
Everything Armada does is an operation on notes — the private records of value inside the pool (see Core concepts). A unit of value starts as public USDC, is shielded into a note, moves privately as notes are spent and recreated, and is eventually unshielded back to public USDC.
| Operation | What it does | Protocol fee | What's visible on-chain |
|---|---|---|---|
| Shield | Public USDC → a shielded note | Shield fee | The deposit amount and depositing address |
| Private transfer | Move value between notes inside the pool | Free | Opaque data only — no amounts or parties |
| Unshield | A shielded note → public USDC | Free | The withdrawn amount + recipient |
| Shielded yield | Earn yield on shielded value | Yield fee (on withdrawal) | The vault deposit/redeem amounts |
| Payments | Send a claimable shielded payment | Built on transfer | Opaque data only, as for a transfer |
A relayer may charge its own fee to submit a transaction on your behalf, separate from the protocol fees above. A relayer is not merely a gas convenience, though: for operations that spend shielded notes (transfers, unshields, shielded yield), submitting through one keeps your own funded, public address off the transaction, which is part of what preserves your privacy. See Fees.
Shield
Shielding deposits public USDC and gives you a private balance — a note (a commitment) in the pool. It runs locally on the hub (PrivacyPool.shield → the Shield module) or from another chain over CCTP (see Cross-chain flow).
The deposit transaction itself is public — an observer can see that some address moved USDC into the pool. What shielding buys you is that everything you do afterward with that value is private and unlinkable. Shield is the one everyday operation that charges a protocol fee: the shield fee (Armada's take, plus any integrator's fee — see Fees). The new note's amount is public when it is created; once it is spent, nothing links that spend back to the deposit.
A shield can also be gasless, so the depositor never needs to hold ETH. The user signs a USDC permit and a shield intent that fixes every note to be created — their own note plus a fee note paying the relayer — and any relayer can submit it, on the hub or from a spoke. The relayer is paid with that shielded fee note, which pays the shield fee like any other deposit. A gasless shield is still a public deposit: the depositing address is recorded on-chain, exactly as in a direct shield.
Private transfer
A transfer moves value between participants entirely inside the pool. It spends one or more of your notes — publishing their nullifiers so they can't be reused — and creates new notes for the recipients, all in one zero-knowledge-proven transaction. No amounts, senders, or recipients are revealed, no value leaves the pool, and there is no protocol fee.
This is where Armada's privacy is strongest. An observer sees only that some notes were spent and some were created, with no link between them and no tie to any identity.
Unshield
Unshielding exits the pool. You prove ownership of a note, its nullifier is published, and public USDC is paid out to a recipient you choose — locally on the hub, or to another chain over CCTP (see Cross-chain flow). Unshielding is free.
An unshield reveals the withdrawn amount and the recipient — it is a public payout — but not which shielded note it came from. The nullifier cannot be linked back to your commitment, so the exit is not tied to your deposit or your in-pool history. Unshields are always available; no role can pause them, including after wind-down.
What's public, what's private
Shielding and unshielding touch the public world, so their amounts are visible; the privacy is in the unlinkability between them. Transfers in between are fully private. The privacy model covers exactly what is and isn't hidden.