x402-privacy-adapter

Buyer-side privacy adapter for x402 payments using a ZK note pool on EVM.

Install

npm install x402-privacy-adapter

Smart Contract Setup

You need a deployed PrivacyPoolUSDC and local circuit artifacts (wasm + zkey). In this repo:

1. npm run zk:compile
2. npm run zk:setup
3. npm run zk:export-verifier
4. npm run compile
5. npm run deploy:base

The deployed pool address is written to deployments/base-mainnet.json. Full steps live in docs/QUICKSTART.md.

Quickstart (CLI)

x402-privacy init \
  --rpc https://... \
  --pk 0x... \
  --chain 8453 \
  --pool 0x... \
  --usdc 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 \
  --wasm ./circuits/build/spend_js/spend.wasm \
  --zkey ./circuits/build/spend_final.zkey

x402-privacy deposit --amount 10000000
x402-privacy buy --url https://merchant.example/api

Programmatic Usage

import { PrivacyAdapter } from 'x402-privacy-adapter';

const adapter = new PrivacyAdapter({
  rpcUrl: 'https://...',
  privateKey: '0x...',
  chainId: 8453,
  poolAddress: '0x...',
  usdcAddress: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913',
  circuitWasmPath: './circuits/build/spend_js/spend.wasm',
  zkeyPath: './circuits/build/spend_final.zkey'
});

await adapter.init();
await adapter.depositPack(10_000_000n);
const res = await adapter.buy('https://merchant.example/api');

Notes

• No fallback: if privacy conditions are not met the adapter throws.
• Requires local proving artifacts (wasm + zkey).
• Uses fixed denominations (5/10/20/50/100 USDC base units).