@erudite-intelligence/x402-ada

x402 exact payment scheme implementation for Cardano ADA.

Part of the EruditePay x402 multi-chain payment infrastructure by Erudite Intelligence LLC.

Overview

This package implements the x402 protocol's exact payment scheme for the Cardano network. It enables HTTP 402-based micropayments using native ADA transfers.

• CAIP-2 Network ID: cardano:764824073
• Unit: lovelace (1 ADA = 1,000,000 lovelace)
• Signing: Ed25519 via cardano-serialization-lib
• Verification: Blockfrost.io API

Installation

npm install @erudite-intelligence/x402-ada

Requires: A Blockfrost.io API key (free tier available).

Usage

Client — Create a Payment

import { createPayment } from "@erudite-intelligence/x402-ada";

const paymentHeader = await createPayment({
  senderAddress: "addr1q...",
  senderPrivateKeyHex: "abcdef1234...",
  recipientAddress: "addr1q...",
  amountLovelace: "2000000",       // 2 ADA
  blockfrostApiKey: "mainnetXYZ...",
  ttlSlots: 7200,
  network: "mainnet",
});

Server — Verify & Settle

import { verifyAndSettle } from "@erudite-intelligence/x402-ada";

const result = await verifyAndSettle({
  paymentHeader: req.headers["x-payment"],
  expectedRecipient: "addr1q...",
  expectedAmountLovelace: "2000000",
  blockfrostApiKey: "mainnetXYZ...",
  network: "mainnet",
});

if (result.success) {
  console.log("Settled:", result.txHash);
} else {
  console.error("Payment failed:", result.error);
}

Security

• Replay protection: In-memory Map with 1-hour TTL. Multi-instance deployments MUST use Redis/DB.
• Fail-closed: If balance verification or Blockfrost API fails, the payment is REJECTED.
• Output verification: Transaction outputs are inspected to confirm payment to the correct address and amount.
• TTL enforcement: Transactions past their TTL slot are rejected.

License

MIT — Erudite Intelligence LLC