asp.net USES the cookie and md5 encryption implementation to remember the password function of the implementation code

When doing the login function of the front desk and the information audit management function of the background, it is necessary to remember the password module:
Although.net built-in login control, has the function of remembering password, but still want to practice 1, the following code mainly applies COOKIE, including the process of security encryption.

// Set, delete Cookie
//provider ofstack.com
        protected void set_cookie()
        {
            HttpCookie UserNameCookie = Request.Cookies["UserNameCookie"];
            HttpCookie UserPasswordCookie = Request.Cookies["UserPasswordCookie"];
            if (this.CheSave.Checked)
            {
                lblcookie.Text = "1";
                // Save the username and password to cookie
                if (UserNameCookie == null)
                {
                    UserNameCookie = new HttpCookie("UserNameCookie");
                    UserNameCookie.Values.Add("UserName", TxtUserName.Text);
                    UserNameCookie.Expires = DateTime.Now.AddDays(30);
                    Response.Cookies.Add(UserNameCookie);
                }
                // Modify the COOKIE
                else if (UserNameCookie.Values["UserName"] != TxtUserName.Text)
                {
                    SetToCookie(UserNameCookie, "UserName", TxtUserName.Text);
                }
                if (UserPasswordCookie == null)
                {
                    UserPasswordCookie = new HttpCookie("UserPasswordCookie");
                    string password1 = FormsAuthentication.HashPasswordForStoringInConfigFile(TxtUserPassword.Text, "MD5");     // If you re - specify the user password, re-encrypt the password 
                    UserPasswordCookie.Values.Add("UserPassword", password1);
                    UserPasswordCookie.Expires = DateTime.Now.AddDays(30);
                    Response.Cookies.Add(UserPasswordCookie);
                }
                else if (UserPasswordCookie.Values["UserPassword"] != FormsAuthentication.HashPasswordForStoringInConfigFile(TxtUserPassword.Text, "MD5") && TxtUserPassword.Text != "1234567890")  
                // " 1234567890 "Is now in the password box 10 A character. 
                {
                    SetToCookie(UserPasswordCookie, "UserPassword", FormsAuthentication.HashPasswordForStoringInConfigFile(TxtUserPassword.Text, "MD5"));
                }
            }
            else
            {
                lblcookie.Text = "0";
                // from cookie Delete the username and password 
                if (Response.Cookies["UserNameCookie"] != null)
                {
                    HttpCookie myCookie = new HttpCookie("UserNameCookie");
                    myCookie.Expires = DateTime.Now.AddDays(-1d);
                    Response.Cookies.Add(myCookie);
                }
                if (Response.Cookies["UserPasswordCookie"] != null)
                {
                    HttpCookie myCookie = new HttpCookie("UserPasswordCookie");
                    myCookie.Expires = DateTime.Now.AddDays(-1d);
                    Response.Cookies.Add(myCookie);
                }
            }
        }
        // Check for presence COOKie situation 
        public void check_cookie()
        {
            HttpCookie UserNameCookie = Request.Cookies["UserNameCookie"];
            HttpCookie UserPasswordCookie = Request.Cookies["UserPasswordCookie"];
            if (UserNameCookie != null)
            {
                this.CheSave.Checked = true;
                TxtUserName.Text = UserNameCookie.Values["UserName"];
            }
            if (UserPasswordCookie != null)
            {
                TxtUserPassword.Attributes.Add("value", "1234567890");// Sets the initial value of the password box 
            }
        }
        public string getpassword()
        {
            HttpCookie UserPasswordCookie = Request.Cookies["UserPasswordCookie"];
            string strpwd = "";  // Gets the comparison of this password string with the density in the data store. 
            if (lblcookie.Text == "1")
            {
                strpwd = UserPasswordCookie.Values["UserPassWord"];// Direct access to COOKIE Password value in 
            }
            else
            { 
                strpwd= FormsAuthentication.HashPasswordForStoringInConfigFile(TxtUserPassword.Text, "MD5"); // Encrypt the password 
            }
            return strpwd;  // Return password field     
        }  
        // Modify the COOKIE This is the way it works 
        public void SetToCookie(HttpCookie httpcookie, string cookiename, string cookievalue)
        {
            httpcookie.Values[cookiename] = cookievalue;
            httpcookie.Expires = DateTime.Now.AddDays(30);
            Response.Cookies.Add(httpcookie);
        }
    }