Xor application in visual C# 2010

using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;
using System.IO;
using System.Diagnostics;

namespace ConsoleApplication1
{
    class Program
    {



            public static string EncryptDecrypt(string textToEncrypt, int encryptionKey)
            {
                StringBuilder inSb = new StringBuilder(textToEncrypt);
                StringBuilder outSb = new StringBuilder(textToEncrypt.Length);
                char c;
                for (int i = 0; i < textToEncrypt.Length; i++)
                {
                    c = inSb[i];
                    c = (char)(c ^ encryptionKey);
                    outSb.Append(c);
                }
                return outSb.ToString();
            }



        static void Main(string[] args)
        {
            ArrayList openArray = new ArrayList();
            ArrayList closeArray = new ArrayList();

            Console.WriteLine("+----------------------+");
            Console.WriteLine("+  ------------------  +");
            Console.WriteLine("+  Encryption Program  +");
            Console.WriteLine("+  ------------------  +");
            Console.WriteLine("+----------------------+");
            Console.WriteLine("");
            Console.WriteLine("");
            Console.WriteLine("Enter the path of the file to be encrypted/decrypted...");
            string beginPath = Console.ReadLine();
            Console.WriteLine("Enter the path of the output file.");
            string endPath = Console.ReadLine();
            Console.WriteLine("Enter a encryption key. No letters or special characters, only numbers.");
            int enKey = Convert.ToInt32(Console.ReadLine());

            using (FileStream fs = new FileStream(beginPath, FileMode.Open, FileAccess.Read))
            {
                using (StreamReader sr = new StreamReader(fs))
                {
                    while (!sr.EndOfStream)
                    {
                        openArray.Add(sr.ReadLine());
                    }
                    sr.Close();
                }
                fs.Close();

            }

            foreach (string line2 in openArray)
            {
                closeArray.Add(EncryptDecrypt(line2, enKey));
            }

            TextWriter tw = new StreamWriter(endPath);

            foreach (string encoded in closeArray)
            {
                tw.WriteLine(encoded);
            }

            tw.Close();

            Console.WriteLine("Encoding finished.");
            Console.WriteLine("Opening output file now...");
            Process.Start("notepad.exe",endPath);

        }
    }
}