C#/.net微信小程序encryptedData解密

public string AES_decrypt(string encryptedDataStr, string key, string iv)
{
RijndaelManaged rijalg = new RijndaelManaged();
//-----------------
//设置 cipher 格式 AES-128-CBC

rijalg.KeySize = 128;

rijalg.Padding = PaddingMode.PKCS7;
rijalg.Mode = CipherMode.CBC;

rijalg.Key = Convert.FromBase64String(key);
rijalg.IV = Convert.FromBase64String(iv);

byte[] encryptedData= Convert.FromBase64String(encryptedDataStr);
//解密
ICryptoTransform decryptor = rijalg.CreateDecryptor(rijalg.Key, rijalg.IV);

string result;

using (MemoryStream msDecrypt = new MemoryStream(encryptedData))
{
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
{
using (StreamReader srDecrypt = new StreamReader(csDecrypt))
{

result;= srDecrypt.ReadToEnd();
}
}
}

return result;
}