AuthorizeNet Webhook HMAC-SHA512 Verification in Lambda NodeJS

const crypto = require('crypto');
...
const header = event.headers['X-ANET-Signature'];

const body = event.body;

const hash = crypto.createHmac('sha512', AUTHORIZENET_SIGNATURE_KEY).update(body).digest('hex');

if (header == `sha512=${hash.toUpperCase()}`) {
  // Verified!
}