資料加密和解密

            if(!File.Exists("c:\\user.ini"))
            {
                StreamWriter sw = new StreamWriter("c:\\user.ini");
                string strName = tbName.Text;
                string strPass = tbPass.Text;
                string strEncryPass = System.Web.Security.FormsAuthentication.
                    HashPasswordForStoringInConfigFile(strPass,"md5");
                sw.WriteLine(strName);
                sw.WriteLine(strEncryPass);
                sw.Close();
                // 資料加密函數System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(strPass,"md5")
            }
            else
            {
                //從user.ini中讀出儲存的使用者名稱稱和密碼，進行比較
                StreamReader sr = new StreamReader("c:\\user.ini");
                string strSaveName = sr.ReadLine();
                string strSavePass = sr.ReadLine();
                sr.Close();
                string strInputPass = System.Web.Security.FormsAuthentication
                    .HashPasswordForStoringInConfigFile(tbPass.Text,"md5");
                if(strSaveName!=tbName.Text||strSavePass!=strInputPass)
                {
                    Response.Write("使用者名稱稱或密碼錯誤！");
                    mainPanel.Visible = false;
                }
                else
                    Response.Write("<script language = javascript>alert('成功登入!')</script>");
            }

資料加密
    方法一：