function uint8ArrayToHex(uint8Array) {
  return Array.prototype.map.call(uint8Array, x => ('0' + x.toString(16)).slice(-2)).join('');
}

async function generateHmac({ secretKey, message, hash }) {
  const encoder = new TextEncoder();
  const secretKeyBytes = encoder.encode(secretKey);
  const messageBytes = encoder.encode(message);

  const key = await crypto.subtle.importKey('raw', secretKeyBytes, { name: 'HMAC', hash }, false, ['sign']);

  const signature = await crypto.subtle.sign('HMAC', key, messageBytes);
  const signatureArray = new Uint8Array(signature);
  return uint8ArrayToHex(signatureArray);
}

async function handleRequest(request) {
  const secretKey = 'YOUR_SECRET_KEY';
  // 使用时请修改为需要被签名的信息，一般为多个数据的组合，例如：时间戳+请求相关信息等
  const message = 'YOUR_MESSAGE';

  // hash 取 SHA-1、SHA-256、SHA-384、SHA-512 之一
  const hmac = await generateHmac({ secretKey, message, hash: 'SHA-256' });
  request.headers.set('Authorization', `HMAC-SHA256 ${hmac}`);

  return fetch(request);
}

addEventListener('fetch', event => {
  event.passThroughOnException();
  event.respondWith(handleRequest(event.request));
});