如何用c#实现aes加密字符串后密文为一些乱码，当然保证可以解密

#region 对文件进行加密解密

        static string iv = "libinguest";

        static string key = "sxjadzjs";



        /// <summary>

        /// DES加密偏移量，必须是>=8位长的字符串

        /// </summary>

        public static string IV

        {

            get { return iv; }

            set { iv = value; }

        }



        /// <summary>

        /// DES加密的私钥，必须是8位长的字符串

        /// </summary>

        public static string Key

        {

            get { return key; }

            set { key = value; }

        }



        /// <summary>

        /// 对文件内容进行DES加密

        /// </summary>

        /// <param name="sourceFile">待加密的文件绝对路径</param>

        /// <param name="destFile">加密后的文件保存的绝对路径</param>

        public static void EncryptFile(string sourceFile, string destFile)

        {

       

            if (!File.Exists(sourceFile)) throw new FileNotFoundException("指定的文件路径不存在！", sourceFile);



            byte[] btKey = Encoding.Default.GetBytes(key);

            byte[] btIV = Encoding.Default.GetBytes(iv);

            DESCryptoServiceProvider des = new DESCryptoServiceProvider();

            byte[] btFile = File.ReadAllBytes(sourceFile);

          

         

            using (FileStream fs = new FileStream(destFile, FileMode.Create, FileAccess.Write))

            {

                try

                {

                    using (CryptoStream cs = new CryptoStream(fs, des.CreateEncryptor(btKey, btIV), CryptoStreamMode.Write))

                    {

                        cs.Write(btFile, 0, btFile.Length);

                        cs.FlushFinalBlock();

                    }

                }

                catch

                {

                    throw;

                }

                finally

                {

                    fs.Close();

                }

            }

        }



        /// <summary>

        /// 对文件内容进行DES加密，加密后覆盖掉原来的文件

        /// </summary>

        /// <param name="sourceFile">待加密的文件的绝对路径</param>

        public void EncryptFile(string sourceFile)

        {

            EncryptFile(sourceFile, sourceFile);

        }



        /// <summary>

        /// 对文件内容进行DES解密

        /// </summary>

        /// <param name="sourceFile">待解密的文件绝对路径</param>

        /// <param name="destFile">解密后的文件保存的绝对路径</param>

        public static void DecryptFile(string sourceFile, string destFile)

        {



            if (!File.Exists(sourceFile))

                throw new FileNotFoundException("指定的文件路径不存在！", sourceFile);



            byte[] btKey = Encoding.Default.GetBytes(key);

            byte[] btIV = Encoding.Default.GetBytes(iv);

            DESCryptoServiceProvider des = new DESCryptoServiceProvider();

            byte[] btFile = File.ReadAllBytes(sourceFile);

          

           

            using (FileStream fs = new FileStream(destFile, FileMode.Create, FileAccess.Write))

            {

                try

                {

                    using (CryptoStream cs = new CryptoStream(fs, des.CreateDecryptor(btKey, btIV), CryptoStreamMode.Write))

                    {

                        cs.Write(btFile, 0, btFile.Length);

                        cs.FlushFinalBlock();

                    }

                }

                catch

                {

                    throw;

                }

                finally

                {

                    fs.Close();

                }

            }

        }



        /// <summary>

        /// 对文件内容进行DES解密，加密后覆盖掉原来的文件

        /// </summary>

        /// <param name="sourceFile">待解密的文件的绝对路径</param>

        public static void DecryptFile(string sourceFile)

        {

            DecryptFile(sourceFile, sourceFile);

        }



        #endregion