C#

Int32 port = 31008;

                IPAddress localAddr = IPAddress.Any;
                server = new TcpListener(localAddr, port);
                server.Start();

                // Buffer for reading data
                Byte[] bytes = new Byte[256];
                String data = null;

                while (true)
                {
                    client = server.AcceptTcpClient();
                    data = null;
                    NetworkStream stream = client.GetStream();

                    int i;

                    while ((i = stream.Read(bytes, 0, bytes.Length)) != 0)
                    {
                        data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
                        data = data.ToUpper();
                        byte[] msg = System.Text.Encoding.ASCII.GetBytes(data);
                        
                        SendMulticast(MultiCastIP, MultiCastPort, msg);
                    }
                    client.Close();
                }

[Serializable]
class Parent
{
  protected int SomeField;
}

[Serializable]
class Child : Parent
{
  [NonSerialized]
  protected int SomeField;
}

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

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            openFD.Title = "Insert a File";
            openFD.InitialDirectory = "F://";
            openFD.FileName = "";
            DialogResult result = openFD.ShowDialog();
            string filename;
            filename = openFD.FileName;
            if (result == DialogResult.OK)
            {

                textBox2.Text = filename;

            }
            else
            {
                return;
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            string password = textBox1.Text;
            string salt_value = "abcdefg";
            string hash = "sha1";
            int passwordIterations = 10;
            string initVector = "@1A2C5D1F286AB54";
            int keySize = 128;
            Encrypt(@"filename", @"C:\Encrypted.ppt", password, salt_value, hash, passwordIterations, initVector, keySize);
           
        }
        public static void Encrypt(string _inputFile, string _outputFile, string password, string salt_value, string hash, int passwordIteration, string initVector, int keySize)
        {
            if (password.Length > 8)
                password = password.Substring(0, 8);
            else if (password.Length < 8)
            {
                int add = 8 - password.Length;
                for (int i = 0; i < add; i++)
                    password = password + i;
            }
            byte[] initVectorBytes = Encoding.ASCII.GetBytes(initVector);
            byte[] salt_valueBytes = Encoding.ASCII.GetBytes(salt_value);
            PasswordDeriveBytes key = new PasswordDeriveBytes(password, salt_valueBytes, hash, passwordIteration);
            byte[] keyBytes = key.GetBytes(keySize / 8);

            FileStream fsCrypt = new FileStream(_outputFile, FileMode.Create);


            RijndaelManaged RMCrypto = new RijndaelManaged();
            RMCrypto.Mode = CipherMode.CBC;
            CryptoStream cs = new CryptoStream(fsCrypt, RMCrypto.CreateEncryptor(keyBytes, initVectorBytes), CryptoStreamMode.Write);

            FileStream fsIn = new FileStream(_inputFile, FileMode.OpenOrCreate);
            int data;
            while ((data = fsIn.ReadByte()) != -1)
                cs.WriteByte((byte)data);

            fsIn.Close();
            cs.Close();
            fsCrypt.Close();
            cs = null;
            fsIn = null;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            openFD.Title = "Insert a File";
            openFD.InitialDirectory = "F://";
            openFD.FileName = "";
            DialogResult result = openFD.ShowDialog();
            string filename;
            filename = openFD.FileName;
            if (result == DialogResult.OK)
            {

                textBox3.Text = filename;

            }
            else
            {
                return;
            }
        }

        private void button4_Click(object sender, EventArgs e)
        {
            string password = textBox1.Text;
            string salt_value = "abcdefg";
            string hash = "sha1";
            int passwordIterations = 10;
            string initVector = "@1A2C5D1F286AB54";
            int keySize = 128;
            Decrypt(@"filename", @"C:\Decrypted.ppt", password, salt_value, hash, passwordIterations, initVector, keySize);
           
        }

        public static void Decrypt(string _inputFile, string _outputFile, string password, string salt_value, string hash, int passwordIteration, string initVector, int keySize)
        {
            if (password.Length > 8)
                password = password.Substring(0, 8);
            else if (password.Length < 8)
            {
                int add = 8 - password.Length;
                for (int i = 0; i < add; i++)
                    password = password + i;
            }
            byte[] initVectorBytes = Encoding.ASCII.GetBytes(initVector);
            byte[] salt_valueBytes = Encoding.ASCII.GetBytes(salt_value);
            PasswordDeriveBytes key = new PasswordDeriveBytes(password, salt_valueBytes, hash, passwordIteration);
            byte[] keyBytes = key.GetBytes(keySize /8);

            FileStream fsCrypt = new FileStream(_outputFile, FileMode.Create);

            RijndaelManaged RMCrypto = new RijndaelManaged();
            RMCrypto.Mode = CipherMode.CBC;
            CryptoStream cs = new CryptoStream(fsCrypt, RMCrypto.CreateDecryptor(keyBytes, initVectorBytes), CryptoStreamMode.Write);




            FileStream fsIn = new FileStream(_inputFile, FileMode.OpenOrCreate);
            int data;
            while ((data = fsIn.ReadByte()) != -1)
                cs.WriteByte((byte)data);

            cs.Close();~IndexOutOfRangeException was unhandled
            fsIn.Close();
            fsCrypt.Close();

            cs = null;
            fsIn = null;
            fsCrypt = null;
        }
    }
}