@erudite-intelligence/x402-atom

x402 exact payment scheme implementation for Cosmos Hub ATOM.

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 Cosmos Hub. It enables HTTP 402-based micropayments using native ATOM bank/MsgSend transfers via CosmJS.

• CAIP-2 Network ID: cosmos:cosmoshub-4
• Unit: uatom (1 ATOM = 1,000,000 uatom)
• Signing: Secp256k1 via @cosmjs/proto-signing
• Verification: Cosmos RPC (Stargate)

Installation

npm install @erudite-intelligence/x402-atom

Usage

Client — Create a Payment

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

const paymentHeader = await createPayment({
  senderMnemonic: "abandon abandon ... about",
  recipientAddress: "cosmos1abc...",
  amountUatom: "1000000",  // 1 ATOM
  network: "mainnet",
  memo: "x402 payment",
});

Server — Verify & Settle

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

const result = await verifyAndSettle({
  paymentHeader: req.headers["x-payment"],
  expectedRecipient: "cosmos1abc...",
  expectedAmountUatom: "1000000",
  network: "mainnet",
});

if (result.success) {
  console.log("Settled:", result.txHash, "Height:", result.height);
}

Security

• Replay protection: In-memory Map with 1-hour TTL. Multi-instance deployments MUST use Redis/DB.
• Fail-closed: If balance query or RPC call fails, the payment is REJECTED.
• Tx hash verification: Transaction bytes are hashed (SHA-256) for replay detection before broadcast.

License

MIT — Erudite Intelligence LLC