code: function xor(a, b) {
    if (!Buffer.isBuffer(a)) a = Buffer.from(a);
    if (!Buffer.isBuffer(b)) b = Buffer.from(b);
    const length = Math.max(a.length, b.length);
    const res = [];
  
    for (let i = 0; i < length; i += 1) {
      res.push(a[i] ^ b[i]);
    }
  
    return Buffer.from(res).toString('base64');
  }
docs: XOR two buffers