Protected transfer

A protected transfer locks USDC in a contract instead of sending it straight to an address. The recipient claims it with a short code; if the address was wrong or poisoned, the wrong party cannot claim and you reclaim. It replaces the “send $1 first and wait” ritual.

Send

import { approveUsdc, sendProtected, generateClaimCode, parseUsdc } from '@ctrl-arcz/sdk';

const amount = parseUsdc('5');
const secret = generateClaimCode(); // { code, salt, claimHash }

await approveUsdc(clients, amount);
const { transferId, txHash, deadline } = await sendProtected(clients, {
  configId, to: recipient, amount, claimHash: secret.claimHash,
});

Give the recipient the code. Anyone can submit the claim, but the funds always go to the recorded recipient, so a claim is front-run-safe.

Claim

import { claim } from '@ctrl-arcz/sdk';

const claimed = await claim(clients, transferId, code, salt);

A wrong code does not revert; it returns false and counts an attempt. After 5 wrong attempts the transfer locks (anti-brute-force). The SDK claim throws on a failed attempt, so check its result rather than treating a mined tx as success.

Cancel and refund

Unclaimed money belongs to the sender. There is no deadline on getting it back.

cancel(transferId)

Sender only, allowed any time before a claim lands, and on a locked transfer.

reclaimExpired(transferId)

Callable by anyone once the recall window lapses; funds only ever go back to the sender. No keeper required.

import { cancel, reclaimExpired, getTransfer } from '@ctrl-arcz/sdk';

await cancel(clients, transferId);
await reclaimExpired(clients, transferId);
const t = await getTransfer(clients, transferId); // status, deadline, attempts, ...

Approve-less sends

To skip a per-send approve, use Permit2: one-time approvePermit2(clients), then sendProtectedWithPermit signs an off-chain permit per send.

import { approvePermit2, sendProtectedWithPermit } from '@ctrl-arcz/sdk';

await approvePermit2(clients); // once
await sendProtectedWithPermit(clients, { configId, to, amount, claimHash });

Get started

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Concepts

Reference

Protected transfer

Send

Claim

Cancel and refund

cancel(transferId)

reclaimExpired(transferId)

Approve-less sends

​Send

​Claim

​Cancel and refund

cancel(transferId)

reclaimExpired(transferId)

​Approve-less sends

Send

Claim

Cancel and refund

Approve-less sends