x402 privacy
x402 privacy
x402 is HTTP-native, but the payment proof it carries exposes the paying wallet's address. x402 privacy routes each 402-payment-required response through a fresh, stealth-derived address so the agent stays unlinkable across calls.
Private x402 fetch
Drop-in middleware pays each 402 response from a fresh one-time address.
import { CropsAgent } from "@crops/agent-sdk";
import { x402Middleware } from "@crops/x402";
const agent = new CropsAgent({
metaAddress: process.env.AGENT_META_ADDRESS,
spendKey: process.env.AGENT_SPEND_KEY,
chain: "base",
});
const fetch = x402Middleware(agent);
await fetch("https://api.example.com/inference");Is x402 private?
By default, no. x402 carries a payment proof inside an HTTP header. The proof contains the payer's address and a signature, and the server uses that address to verify payment on-chain.
That makes the default setup a worst case for agent privacy: one signing address pays every API the agent calls, and every recipient can read that address's full history.
What x402 leaks about an agent
The signing address appears in the payment header and in the on-chain transaction. The payment graph leaks because multiple servers see the same address. The funding source leaks because the agent's signing address was funded from somewhere visible.
Stealth-address routing breaks all three links. Each call carries a one-time address, with no shared address to correlate.
How to add privacy to x402
The CROPS.cash SDK includes x402 middleware that drops into any HTTP client. The server can still verify payment, but the address used for each payment is fresh.
Server returns 402 Payment Required with token, amount, chain, and recipient.
Agent middleware derives a one-time address for the payment.
Middleware signs and broadcasts the payment from that one-time address.
Middleware retries the request with the payment proof attached.
Can x402 payments be audited?
Yes. Stealth routing does not delete the audit trail. It moves the trail from public clustering to key-controlled disclosure. The operator can share a view key with finance, an auditor, or compliance for a specific period.
Default x402 wallet vs stealth-routed x402
| Default x402 wallet | Stealth-routed x402 |
|---|---|
| One address across calls | Fresh address per call |
| Recipient can inspect history | Recipient sees only current payment |
| Funding source is one query away | Funding does not appear as a direct hop |
| Public clustering by default | View-key audit by authorization |
Frequently asked questions
Is x402 private by default?
No. The payment proof exposes the paying wallet address, and the server can use that address to inspect the agent's history.
How do you add privacy to x402?
Route each payment through a fresh stealth-derived address using x402 middleware.
Can the x402 server still verify payment?
Yes. It verifies the on-chain transfer as usual. The payer address is just a fresh one-time address.
Is x402 privacy compatible with auditing?
Yes. A view key lets authorized parties reconstruct payment history without exposing it publicly.