zx402 Tests Private Funding for AI Agents on Cardano

zx402 has documented two service purchases on Cardano Preprod using a pool designed to separate an AI agent’s spending from its original wallet. The October 7 tests address a privacy problem for automated commerce: public payment histories can reveal an agent’s suppliers, purchasing frequency, and operating budget.

Two Purchases Through x402 and Masumi

The first demonstration paid a weather service through x402, which uses HTTP 402 to request payment. The response cost 2 tUSDM, with a separate fee for the relayer submitting the pool transaction.

Using previously deposited funds, the pool financed a fresh one-time address that completed a standard x402 payment. The service returned a weather response, while the remaining balance stayed in the pool for another purchase.

The second test paid the Masumi agent “Expose: Web Single Answer” 0.01 tUSDM to explain a zero-knowledge proof in one sentence. Here, the pool funded the purchasing wallet of a Masumi payment node. Funds then entered Masumi escrow, and the published log recorded the task as completed.

The distinction matters to the payment flow: the x402 test used a one-time address, while the Masumi test funded an existing purchasing wallet. The team published terminal logs and transaction links for both runs, which used test tokens rather than mainnet funds.

How the Cardano Privacy Pool Works

An agent deposits funds publicly and keeps a private note recording its claim to them. Once the deposit is approved, the agent generates a zero-knowledge proof locally, demonstrating ownership of approved, unspent funds without identifying the deposit behind the purchase.

A relayer submits the proof and transaction. In the standard x402 flow, the pool funds a new one-time address before payment reaches the seller. According to the documentation, sellers can accept these payments without integrating zx402-specific code. Unspent funds become a new private note available for later purchases.

Privacy has defined limits. Amounts, timing, and outgoing pool payments remain visible. A small pool or matching amounts can make transactions easier to correlate, while publicly withdrawing the remaining balance can expose connections to earlier purchases.

The agent’s blockchain infrastructure provider can also observe its addresses and requests. The design therefore targets the public link between funding and spending, with additional privacy depending on how the agent accesses the network.

What Remains Before Mainnet

The source code, SDK, and testing instructions are available to developers. The public website provides documentation but does not connect wallets or execute transactions.

Deposit approval is implemented, although external screening is not. The current service approves deposits unless a configured denial function rejects them; no screening data source is connected.

Costs also shape the intended use. Cardano outputs must contain a minimum amount of ADA, so the team positions the pool for larger payments, escrow funding, and payment channels rather than individual blockchain transactions for every inexpensive API request.

Mainnet deployment remains pending, and nobody outside the project has reviewed its design or code. Before accepting outside funds, zx402 lists a multiparty cryptographic setup and an external security audit among its requirements. It also needs a new pool with blockchain checks that enforce the correct starting state, replacing the current reliance on the deployer to initialize it correctly.