Agents that pay each other onchain expose every invoice, fee, and settlement to the public. Confidential transfers let an agent hold a balance and pay other agents without revealing amounts, while addresses stay transparent so regulated parties can still produce per-transaction details through selective disclosure.
Agents use the same @fairblock/stabletrust SDK as any other integration, driven from a server or agent runtime. See Building an App with the SDK for the full walkthrough and the Method Reference for every method signature.

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What you can build

  • Agent-to-agent payments where amounts and balances stay encrypted between the two agents
  • x402 payments with confidential transfers: fast, confidential micro-payments for subscriptions, APIs, or AI agents

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Using the SDK

An agent transacts with the ConfidentialTransferClient using an ethers.Wallet. The end-to-end confidential flow is: 
import { ConfidentialTransferClient } from "@fairblock/stabletrust";
import { ethers } from "ethers";

const client = new ConfidentialTransferClient(
  "https://sepolia.base.org",
  84532,
);
const wallet = new ethers.Wallet(process.env.PRIVATE_KEY);
const tokenAddress = "0xYourTokenAddress";
const tokenDecimals = 6;

// 1. Ensure account exists and get encryption keys
const keys = await client.ensureAccount(wallet);

// 2. Deposit
const depositAmount = ethers.parseUnits("10", tokenDecimals);
await client.confidentialDeposit(wallet, tokenAddress, depositAmount);

// 3. Check balance
const balance = await client.getConfidentialBalance(
  wallet.address,
  keys.privateKey,
  tokenAddress,
);
console.log(
  "Available:",
  ethers.formatUnits(balance.available.amount, tokenDecimals),
);

// 4. Transfer (recipient must have called ensureAccount)
const transferAmount = ethers.parseUnits("5", tokenDecimals);
await client.confidentialTransfer(
  wallet,
  recipientAddress,
  tokenAddress,
  transferAmount,
);

// 5. Withdraw
const withdrawAmount = ethers.parseUnits("2", tokenDecimals);
await client.withdraw(wallet, tokenAddress, withdrawAmount);

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Hiding the agent’s address

A standard confidential transfer keeps amounts and balances encrypted, but the sender’s wallet address remains visible onchain. To hide the agent’s address as well, use the AnonymousTransferClient, which routes transfers through the Fairycloak relay so only a numeric account ID appears onchain. See Anonymous Transfers.

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Security considerations

  • Private key management: never expose or log private keys; store them securely (e.g. hardware wallets, encrypted vaults). Derived account privateKey values are equally sensitive.
  • Account initialization: always call ensureAccount() before any operation, and verify that recipient accounts exist before transferring funds.
  • Balance verification: check available balance before initiating transfers.
  • Error handling: implement retry logic for transient network failures.

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Next steps

Build an App with the SDK

The full SDK walkthrough this guide builds on.

Method Reference

Every client method, parameter, and return type.

Anonymous Transfers

Hide the agent’s address as well as the amount.

Common Errors

Failure modes and how to handle them.