Szyfrowanie / zapis / odczyt C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.IO;
using System.Security.Cryptography;
using System.Windows.Forms;

namespace WindowsFormsApplication5
{
    public partial class Form1 : Form
    {
        private String opcje = "test.txt";
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //Zamykanie okna
            Close();
        }

        private void panel2_Paint(object sender, PaintEventArgs e)
        {
            double A = trackBar1.Value / 100.0;
            double L = trackBar2.Value / 100.0;
            double F = trackBar3.Value / 100.0;
            double k = 2 * Math.PI / L;

            Graphics g = e.Graphics;

            Diagram d = new Diagram(0, 0, panel2.Width, panel2.Height, 0, 0, 2, 2, e.Graphics);
            d.siatka(0, 0, -1, 1, -1, 1, 0.1, 0.1, Color.Green);
            d.uklad_xy(0, 0, -1, 1, -1, 1, 0.1, 0.1, 5, Color.Blue);

            double x,y;

            for (x = -1; x <= 1; x += 0.001)
            {

                y = A * Math.Sin(k * x + F);
                d.punkt(x, y, 3, TypPunktu.P_Kolo, Color.Red);
            }
        }

        private void trackBar3_ValueChanged(object sender, EventArgs e)
        {
            panel2.Invalidate();
        }

        private void panel2_Resize(object sender, EventArgs e)
        {
            panel2.Invalidate();
        }

        private void Form1_FormClosed(object sender, FormClosedEventArgs e)
        {


            // deklaracja zapisu do pliku
            FileStream fs = new FileStream(opcje, FileMode.OpenOrCreate);

            DESCryptoServiceProvider crypt = new DESCryptoServiceProvider();
            crypt.Key = new Byte[]{ 71, 72, 83, 84, 85, 96, 97, 78 };
            crypt.IV = new Byte[] { 71, 72, 83, 84, 85, 96, 97, 78 };
            CryptoStream cs = new CryptoStream(fs, crypt.CreateEncryptor(), CryptoStreamMode.Write);

            // obiekt ktory pisze do strumienia ktory zapisze do pliku
            StreamWriter sw = new StreamWriter(cs);
            sw.WriteLine(trackBar1.Value);
            sw.WriteLine(trackBar2.Value);
            sw.WriteLine(trackBar3.Value);
            sw.Close();
            fs.Close();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            FileStream fs = new FileStream(opcje, FileMode.Open);

            DESCryptoServiceProvider crypt = new DESCryptoServiceProvider();
            crypt.Key = new Byte[] { 71, 72, 83, 84, 85, 96, 97, 78 };
            crypt.IV = new Byte[] { 71, 72, 83, 84, 85, 96, 97, 78 };
            CryptoStream cs = new CryptoStream(fs, crypt.CreateDecryptor(), CryptoStreamMode.Read);

            StreamReader sr = new StreamReader(cs);

            trackBar1.Value = Int32.Parse(sr.ReadLine());
            trackBar2.Value = Int32.Parse(sr.ReadLine());
            trackBar3.Value = Int32.Parse(sr.ReadLine());

            sr.Close();
            fs.Close();
        }


    }
}