school/semester_3/racunalniska_omrezja/naloga_4/MyApplication/MainWindow.xaml.cs

using Microsoft.Win32;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace MyApplication
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {

        const int STD_PORT = 1234;
        const string STD_IP = "127.0.0.1";
        const int STD_BUFF = 256;
        string fileName = "";


        public MainWindow()
        {
            InitializeComponent();
        }

        private void Select_Click(object sender, RoutedEventArgs e)
        {
            OpenFileDialog dialog = new OpenFileDialog();
            dialog.FileName = ""; // Default file name
            dialog.DefaultExt = "*."; // Default file extension
            dialog.Filter = "All|*.*"; // Filter files by extension

            bool? result = dialog.ShowDialog();
            if (result == true)
            {
                fileName = dialog.FileName;
                lableAddress.Content = fileName;
                send_Button.IsEnabled = true;
            }
        }
        private void Send_Click(object sender, RoutedEventArgs e)
        {
            lableFinish.Content = "";
            Send();
        }
        private void Recive_Click(object sender, RoutedEventArgs e)
        {
            lableFinish.Content = "";
            Recive();

        }

        private void Recive()
        {
            string downloadsPath = KnownFolders.GetPath(KnownFolder.Downloads);
            TcpListener tcpListener = new TcpListener(IPAddress.Parse(STD_IP), STD_PORT);
            tcpListener.Start();
            using TcpClient tcpClient = tcpListener.AcceptTcpClient();
            using NetworkStream networkStream = tcpClient.GetStream();
            
            //--------------------------------------------------------------------------------------------------Recive Name of File------------------------------------
            byte[] buffer = new byte[STD_BUFF];
            int readBytes = networkStream.Read(buffer, 0, buffer.Length);
            if (readBytes < 0) return;
            string fileName = Encoding.UTF8.GetString(buffer,0, readBytes);
            string fileDestination = downloadsPath + "\\" + fileName;
            lableFileName.Content = fileDestination;

            //-----------------------------------------------------------------------------------------------Send Size of File------------------------------------
            buffer = new byte[STD_BUFF];
            readBytes = networkStream.Read(buffer, 0, buffer.Length);
            if (readBytes < 0) return;
            int bufferCount = BitConverter.ToInt32(buffer, 0);
            lableSize.Content = bufferCount.ToString();


            //-------------------------------------------------------------------------------------------------ECDiffieHellmanCng--------------------
            using ECDiffieHellmanCng eCDiffieHellmanCng = new ECDiffieHellmanCng();

            eCDiffieHellmanCng.KeyDerivationFunction = ECDiffieHellmanKeyDerivationFunction.Hash;
            eCDiffieHellmanCng.HashAlgorithm = CngAlgorithm.Sha256;

            byte[] myPublicKey = eCDiffieHellmanCng.PublicKey.ToByteArray();
            networkStream.Write(myPublicKey, 0, myPublicKey.Length);

            byte[] therePublicKey = new byte[140];
            readBytes = networkStream.Read(therePublicKey, 0, therePublicKey.Length);
            if (readBytes < 0) return;

            CngKey thereKey = CngKey.Import(therePublicKey, CngKeyBlobFormat.EccPublicBlob);
            byte[] Key = eCDiffieHellmanCng.DeriveKeyMaterial(thereKey);

            using Aes aes = Aes.Create();
            aes.Key = Key;
            aes.IV = Encoding.UTF8.GetBytes("sestnajst1616161");
            aes.Mode = CipherMode.CBC;
            aes.Padding = PaddingMode.PKCS7;

            using CryptoStream cryptoStream = new CryptoStream(networkStream, aes.CreateDecryptor(), CryptoStreamMode.Read);
            using FileStream fileStream = new FileStream(fileDestination, FileMode.OpenOrCreate);

            for (int i = 0; i < bufferCount; i++)
            {
                buffer = new byte[STD_BUFF];
                readBytes = cryptoStream.Read(buffer, 0, buffer.Length);
                fileStream.Write(buffer, 0, readBytes);
            }

            cryptoStream.Close();
            aes.Clear();
            eCDiffieHellmanCng.Clear();
            networkStream.Close();
            tcpClient.Close();
            tcpListener.Stop();
            lableFinish.Content = "finished";
        }

        void Send()
        {
            using TcpClient tcpClient = new TcpClient();
            tcpClient.Connect(IPAddress.Parse(STD_IP), STD_PORT);
            using NetworkStream networkStream = tcpClient.GetStream();

            //--------------------------------------------------------------------------------------------------Send Name of File------------------------------------
            string[] fileNames = fileName.Split("\\");
            byte[] nameInBytes = Encoding.UTF8.GetBytes(fileNames.Last());
            networkStream.Write(nameInBytes, 0, nameInBytes.Length);
            lableFileName.Content = fileName;

            using FileStream fileStream = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.Read);
            //-----------------------------------------------------------------------------------------------Send Size of File------------------------------------
            int bufferCount = Convert.ToInt32(Math.Ceiling((double)fileStream.Length / (double)STD_BUFF));
            byte[] size = BitConverter.GetBytes(bufferCount);
            networkStream.Write(size, 0, size.Length);
            lableSize.Content = bufferCount.ToString();

            //-------------------------------------------------------------------------------------------------ECDiffieHellmanCng--------------------
            using ECDiffieHellmanCng eCDiffieHellmanCng = new ECDiffieHellmanCng();
            eCDiffieHellmanCng.KeyDerivationFunction = ECDiffieHellmanKeyDerivationFunction.Hash;
            eCDiffieHellmanCng.HashAlgorithm = CngAlgorithm.Sha256;

            //----------------------------------------------------------------------Send my key--------------
            byte[] myPublicKey = eCDiffieHellmanCng.PublicKey.ToByteArray();
            networkStream.Write(myPublicKey, 0, myPublicKey.Length);

            //-------------------------------------------------------------------Recive there key and create private key------------------------
            byte[] therePublicKey = new byte[140];
            int readByte = networkStream.Read(therePublicKey, 0, therePublicKey.Length);
            if (readByte < 0) return;
            CngKey thereKey = CngKey.Import(therePublicKey, CngKeyBlobFormat.EccPublicBlob);
            byte[] Key = eCDiffieHellmanCng.DeriveKeyMaterial(thereKey);

            //---------------------------------------------------------------------------AES Crete
            using Aes aes = Aes.Create();
            aes.Key = Key;
            aes.IV = Encoding.UTF8.GetBytes("sestnajst1616161");
            aes.Mode = CipherMode.CBC;
            aes.Padding = PaddingMode.PKCS7;

            //----------------------------------------------------------------------------Create crypto strim
            using CryptoStream cryptoStream = new CryptoStream(fileStream, aes.CreateEncryptor(), CryptoStreamMode.Read);
            
            for(int i = 0; i < bufferCount+1; i++)
            {
                byte[] buffer = new byte[STD_BUFF];
                int returndCaunt = cryptoStream.Read(buffer, 0, buffer.Length);
                networkStream.Write(buffer, 0, returndCaunt);
            }

            cryptoStream.Close();
            aes.Clear();
            eCDiffieHellmanCng.Clear();
            networkStream.Close();
            networkStream.Close();
            tcpClient.Close();
            lableFinish.Content = "finished";
        }


        public enum KnownFolder
        {
            Contacts,
            Downloads,
            Favorites,
            Links,
            SavedGames,
            SavedSearches
        }
        public static class KnownFolders
        {
            private static readonly Dictionary<KnownFolder, Guid> _guids = new()
            {
                [KnownFolder.Contacts] = new("56784854-C6CB-462B-8169-88E350ACB882"),
                [KnownFolder.Downloads] = new("374DE290-123F-4565-9164-39C4925E467B"),
                [KnownFolder.Favorites] = new("1777F761-68AD-4D8A-87BD-30B759FA33DD"),
                [KnownFolder.Links] = new("BFB9D5E0-C6A9-404C-B2B2-AE6DB6AF4968"),
                [KnownFolder.SavedGames] = new("4C5C32FF-BB9D-43B0-B5B4-2D72E54EAAA4"),
                [KnownFolder.SavedSearches] = new("7D1D3A04-DEBB-4115-95CF-2F29DA2920DA")
            };

            public static string GetPath(KnownFolder knownFolder)
            {
                return SHGetKnownFolderPath(_guids[knownFolder], 0);
            }

            [DllImport("shell32",
                CharSet = CharSet.Unicode, ExactSpelling = true, PreserveSig = false)]
            private static extern string SHGetKnownFolderPath(
                [MarshalAs(UnmanagedType.LPStruct)] Guid rfid, uint dwFlags,
                nint hToken = 0);
        }

    }
}