cf.js

'use strict';

function hex2bin(hex) {
  const buf = new Uint8Array(Math.ceil(hex.length / 2));
  for (var i = 0; i < buf.length; i++) {
    buf[i] = parseInt(hex.substr(i * 2, 2), 16);
  }
  return buf;
}

const PUBLIC_KEY = crypto.subtle.importKey(
  'raw',
  hex2bin('bef3c62aed7c2711bdb06c58e483c995227b2593d0b5ab6e4a802f6b08c647f4'),
  {
    name: 'NODE-ED25519',
    namedCurve: 'NODE-ED25519',
    public: true,
  },
  true,
  ['verify'],
);

const encoder = new TextEncoder();

async function handleRequest(request) {
  if (request.method !== 'POST') {
    return new Response('invalid method', { status: 405 });
  }
  const signature = hex2bin(request.headers.get('X-Signature-Ed25519'));
  const timestamp = request.headers.get('X-Signature-Timestamp');
  const unknown = await request.text();

  const verified = await crypto.subtle.verify(
    'NODE-ED25519',
    await PUBLIC_KEY,
    signature,
    encoder.encode(timestamp + unknown),
  );
  if (!verified) {
    return new Response('invalid request', { status: 401 });
  }

  const data = JSON.parse(unknown);

  switch (data.type) {
    case 1:
      return new Response(JSON.stringify({ type: 1 }), {
        headers: {'Content-Type': 'application/json'},
      });
    default:
      return new Response('invalid request', { status: 400 });
  }
}

addEventListener('fetch', (event) => {
  event.respondWith(handleRequest(event.request)
    .catch(() => new Response('internal error', { status: 500 })));
});