FAQ
Questions, answered
Everything you should know before putting funds in a pool.
How it works
What does Cloak actually do?+
It breaks the on-chain link between the address that deposits and the address that withdraws. Funds of the same denomination are pooled together; a withdrawal proves membership in the pool with a zero-knowledge proof instead of pointing at a specific deposit.
Why fixed denominations?+
If every deposit were a different amount, matching a withdrawal to its deposit would be trivial. Fixed sizes make all deposits in a pool look identical.
What is in the note?+
Two random 31-byte numbers: a nullifier and a secret. Their Pedersen hash (the commitment) is stored on-chain at deposit time. At withdrawal the proof shows that you know a preimage of some commitment in the tree and reveals the hash of the nullifier so the same note cannot be spent twice.
Where is the proof computed?+
Entirely in your browser, using a Groth16 prover compiled to WebAssembly. The circuit and proving key (≈34 MB) are downloaded on first withdrawal and cached. Your note never leaves the device.
Which zero-knowledge circuit is used?+
The audited tornado-core v2 withdraw circuit (Merkle height 20, MiMC-sponge tree, Pedersen commitments). The on-chain Verifier was generated from the same trusted setup, so Cloak does not introduce new cryptographic assumptions.
Assets & Robinhood Chain
Which assets are supported?+
Native ETH, USDG (Global Dollar) and Robinhood Stock Tokens such as AAPL, TSLA, NVDA and SPY. New tokens and denominations can be added by anyone through the pool factory; this interface lists a curated set.
Do Stock Tokens have transfer restrictions?+
Robinhood Stock Tokens use a blocklist, not an allowlist: any address may hold and transfer them unless it has been specifically blocked. Pools hold raw token balances, so a fixed denomination stays fixed.
What do I pay in gas?+
Robinhood Chain fees are paid in ETH. A deposit is roughly 1M gas (the Merkle tree update dominates); a withdrawal is ~350k gas for the pairing check. There is no protocol fee.
Is there a relayer?+
Not yet. The wallet you connect on the withdraw page sends the transaction and pays gas, so it should be a fresh wallet with a little ETH — ideally the recipient itself. The contracts already support relayers and fees, so one can be added later without redeploying.
Safety
I lost my note. Can you help?+
No. There is no account, no admin key and no backdoor. A lost note means the deposit is unrecoverable by anyone.
How long should I wait before withdrawing?+
As long as you can. Timing is the most common way privacy is broken: withdrawing minutes after depositing, or always withdrawing at the same time of day, links the two. Also prefer pools with a large anonymity set.
Can the team freeze or upgrade the contracts?+
No. The pools, verifier and factory are immutable, non-upgradeable and have no owner. This website can disappear and the funds remain withdrawable with the note and any compatible interface.
Is this legal to use?+
Privacy tools are legal in most jurisdictions, but sanctions and financial regulations vary. You are responsible for complying with the laws that apply to you. Do not use Cloak to launder proceeds of crime or evade sanctions.