关于利用webhook（已加签）向钉钉群发送图片问题，来个大佬解惑。

请看代码和运行结果，最终版，无奈了，找不出原因

const webhkul="https://oapi.dingtalk.com/robot/send?access_token=2f431c1e4267e763a2ad42f441d40b2912be579276caa24d68ec0dd2119c5ed3"
var timestamp =Math.round(new Date().getTime()).toString();
console.log(timestamp)
var secret ="SEC7f0bd98f701dae340674d46a0282b8589d1f243e80ca8cddb6d59eb5c704a99a";
var stringToSign = timestamp + "\n" + secret;
var sign =Crypto.createHash("sha256",secret).update(stringToSign).digest("hex");
console.log(sign2)
var fullWebhookUrl = webhkul + "&timestamp=" + timestamp.toString("base64") + "&sign=" + sign;
console.log(fullWebhookUrl)
const resp2 = HTTP.get("https://img05.tooopen.com/20150401/tooopen_sy_116346892136.jpg")
const body = resp2.binary();
const hash = Crypto.createHash("md5");
const imgBase =body.toString("base64");
console.log(body)
console.log(imgBase)
hash.update(body);
const md5Hash = hash.digest("hex");
HTTP.post(fullWebhookUrl,
  {
  "msgtype": "image",
    "image": {
        "base64": imgBase,
        "md5": md5Hash
    }
  }
)
 HTTP.post(fullWebhookUrl, {
    "msgtype": "text",
    "text": {
      "content": "这是一个image"
    },
  });