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;    
        }