Privacy checklist

The pool hides which notes a transaction spends, who receives a transfer, and transfer amounts. Other data remains observable, and some SDK options reduce privacy. This page lists what an application should configure and communicate to users.

What is public

Data	Visible to	Details
Deposit payer and amount	everyone (on chain)	Denominations
Withdrawal recipient and gross amount	everyone (on chain)	Withdraw
That a shielded transfer occurred, and when	everyone (on chain)	How it fits together
Submitter IP address and timing	relayer	How it fits together
Requested token pair and size	metaquoter	Swap
A handle, the address published under it, and when it was registered	everyone (on chain)	Names
Which handle is looked up, and when	the RPC serving the lookup	Names
RPC reads, including your deposit account	your RPC provider	Networks
Incoming notes (with matches strategy)	FMD server	Syncing

Checklist

Amounts

• Withdraw denominations. Use previewWithdraw and show onLadder: false to the user; offer suggestion instead of changing the amount. A net withdrawal is almost never on the ladder. See Denominations.
• Keep ladders enabled (denominations: true, the default).
• Do not round the net amount. Choosing publicOut so the recipient receives a round figure makes publicOut distinctive.
• Avoid distinctive deposit amounts where the user can choose, since deposits are public.
• Consider DenominationCoinSelector (via createWallet) to reduce change, and run redenominate to keep notes on the ladder.

Timing and linkage

• Spread large withdrawals across blocks and recipients; several withdrawals to one address are linked.
• Keep the spend cooldown (selection.cooldownBlocks, default 1) and use a chain adapter that implements blockNumber, which the cooldown requires. See Spend cooldown.
• Keep the default SFRT selector. Largest-first selection creates a pattern that links spends. See Pluggable interfaces.
• Use recipientCommitment, not an output index, to identify the payee note; outputs are shuffled. See Transfer.
• Give each payer its own address with addressAt(index). Payers comparing addresses then cannot tell they pay the same account. See Addresses.
• Publish only the reserved address under a handle, which registerName does, and hand it out nowhere else. A registration re-shields its change in the same public transaction as that address, so the change is kept to one unit.
• Look a handle up once, when a contact is saved, not before each payment. A lookup followed by a spend lets whoever served the lookup pair them. See Names.
• Accept only names under the parents your deployment lists. lelantos.eth is not one of them. See Names.

Detection and keys

• Keep the full sync strategy unless bandwidth requires matches. Delegating detection cannot be revoked. See Sync strategies.
• In a watch-only wallet, leave allowDetectionKeyRelease unset. The decision belongs to the account owner. See Watch-only wallets.
• Treat viewing keys as permanent disclosure. They cannot be revoked. See Watch-only wallets.
• Treat a payment proof as disclosure of one payment. With the payee's address, its holder reads that output's asset, value and memo; it reveals nothing else. Send it only to whoever should learn it. See Proving a payment.
• Treat a handle's controller key as the handle. Its holder can publish another address under it. Clearing a record stops it resolving but does not erase it from chain history. See Names.
• Treat a claim-link key as the funds. Whoever holds it can spend what the link holds. See Claim-link keys.
• Derive subscription tokens from ivk, and store the epoch after rotating. See Rotating the token.

Network

• Route traffic if IP privacy matters. Pass http: { fetch } to send all SDK service requests through a proxy, and point rpcUrl at an endpoint you trust. See HTTP options.
• Do not query servers per note. Custom NoteSource implementations must not request Merkle paths or nullifier status for specific notes. See Custom note source.

Local data

• Encrypt the notes file at rest. It links its holder to every commitment the wallet owns. See Custom storage.
• Do not log user input verbatim. SDK error messages omit rejected addresses and values; keep application logs consistent with that.

Next

• Denominations
• How it fits together