crypto.subtle.sign()未执行签名？请求排查问题

/*
获取"message"文本框内容，编码为签名操作可用格式
*/
function getMessageEncoding() {
  const messageBox = 'hello world!';
  let message = messageBox.value;
  let enc = new TextEncoder();
  return enc.encode(message);
}

async function main() {
    let encoded = getMessageEncoding();
    window.crypto.subtle.sign(
      {
        name: "ECDSA",
        hash: { name: "SHA-384" },
      },
     {"alg":"ES256","crv":"P-256","d":"KRiXxoIFHmBQJdoCsqB8Bc9_f2Z-QCdRgoydMKdoL04","ext":true,"key_ops":["sign"],"kty":"EC","x":"FKwqyGd4i2NAl8RUXCCBRCAIbcpeGyfyXwgA_AWHb8Y","y":"njxhw5O6zGVkBlcPDKYj0E-6VO1giHTUkJWBhgKNqd8"},
  encoded,
    ).then(signature => {
    console.log(signature);
    alert('test');
  });
  alert(signature);
}

main();

（注：上述私钥为测试用，非生产环境密钥）

运行以上代码后无任何反应，预期将签名输出到JavaScript控制台，以下是具体排查思路：

• DOM元素获取错误：getMessageEncoding函数中messageBox被赋值为字符串'hello world!'，字符串没有value属性，执行messageBox.value会直接抛出错误，导致后续代码无法执行。修复时如果是要获取输入框内容，需改为document.getElementById('message')这类方式获取DOM元素；如果直接用固定字符串，直接用message = 'hello world!'即可。

• 异步变量作用域错误：main函数中最后一行alert(signature)的signature是在then回调内部定义的变量，外部无法访问，且这行代码会在sign异步操作完成前执行，此时signature未定义，会抛出错误。需删除该行，或把逻辑移到then回调内。

• 密钥格式错误：window.crypto.subtle.sign的第二个参数要求传入CryptoKey对象，而代码直接传入了JWK格式的普通对象，无法被识别。需先用crypto.subtle.importKey方法将JWK导入为CryptoKey，示例：

  const jwk = {"alg":"ES256","crv":"P-256","d":"KRiXxoIFHmBQJdoCsqB8Bc9_f2Z-QCdRgoydMKdoL04","ext":true,"key_ops":["sign"],"kty":"EC","x":"FKwqyGd4i2NAl8RUXCCBRCAIbcpeGyfyXwgA_AWHb8Y","y":"njxhw5O6zGVkBlcPDKYj0E-6VO1giHTUkJWBhgKNqd8"};
  const privateKey = await crypto.subtle.importKey(
    'jwk',
    jwk,
    { name: 'ECDSA', hash: 'SHA-256' },
    true,
    ['sign']
  );
  

• 算法参数不匹配：签名时指定的哈希算法是SHA-384，但JWK的alg是ES256（对应SHA-256），算法参数与密钥的算法不兼容，会导致签名操作失败。需将签名配置中的hash改为{ name: "SHA-256" }，保持与密钥算法一致。

• 缺少错误捕获：代码未对异步操作的错误进行捕获，即使执行出错也无法在控制台看到错误信息。建议利用async/await配合try/catch处理错误，或在then后添加catch回调：

  async function main() {
    try {
      let encoded = getMessageEncoding();
      const jwk = {"alg":"ES256","crv":"P-256","d":"KRiXxoIFHmBQJdoCsqB8Bc9_f2Z-QCdRgoydMKdoL04","ext":true,"key_ops":["sign"],"kty":"EC","x":"FKwqyGd4i2NAl8RUXCCBRCAIbcpeGyfyXwgA_AWHb8Y","y":"njxhw5O6zGVkBlcPDKYj0E-6VO1giHTUkJWBhgKNqd8"};
      const privateKey = await crypto.subtle.importKey(
        'jwk',
        jwk,
        { name: 'ECDSA', hash: 'SHA-256' },
        true,
        ['sign']
      );
      const signature = await window.crypto.subtle.sign(
        { name: "ECDSA", hash: { name: "SHA-256" } },
        privateKey,
        encoded
      );
      console.log(signature);
      alert('test');
    } catch (err) {
      console.error('签名失败:', err);
    }
  }
  

内容的提问来源于stack exchange，提问作者neubert