111 lines
3.9 KiB
C#
111 lines
3.9 KiB
C#
using System.IO.Compression;
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using System.Net;
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using System.Net.Sockets;
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using System.Numerics;
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using System.Security.Cryptography;
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using System.Text;
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await Task.WhenAll(ServerTask(), ClientTask());
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await Task.Delay(-1);
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return;
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static async Task ClientTask()
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{
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using var socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
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await socket.ConnectAsync(new IPEndPoint(IPAddress.Loopback, 1234));
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using var aes = Aes.Create();
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aes.GenerateKey();
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aes.GenerateIV();
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await using var stream = new NetworkStream(socket);
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SendAesKey(stream, aes);
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const string message = "Hello";
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Console.WriteLine($"Client sending message: {message}");
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SendEncryptedMessage(Encoding.UTF8.GetBytes(message), stream, aes);
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await Task.Delay(-1);
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}
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static async Task ServerTask()
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{
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using var listener = new Socket(SocketType.Stream, ProtocolType.Tcp);
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listener.Bind(new IPEndPoint(IPAddress.Any, 1234));
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listener.Listen(1);
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using Socket client = await listener.AcceptAsync();
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await using var stream = new NetworkStream(client);
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using var aes = Aes.Create();
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ReadAesKey(stream, aes);
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Console.WriteLine($"Server received message: {Encoding.UTF8.GetString(ReadEncryptedMessage(stream, aes))}");
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await Task.Delay(-1);
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}
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static void ReadAesKey(Stream stream, SymmetricAlgorithm aes)
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{
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using var reader = new BinaryReader(stream, Encoding.UTF8, true);
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aes.Key = reader.ReadBytes(IPAddress.NetworkToHostOrder(reader.ReadInt32()));
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aes.IV = reader.ReadBytes(IPAddress.NetworkToHostOrder(reader.ReadInt32()));
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}
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static void SendAesKey(Stream stream, SymmetricAlgorithm aes)
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{
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using var writer = new BinaryWriter(stream, Encoding.UTF8, true);
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writer.Write(IPAddress.HostToNetworkOrder(aes.Key.Length));
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writer.Write(aes.Key);
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writer.Write(IPAddress.HostToNetworkOrder(aes.IV.Length));
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writer.Write(aes.IV);
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}
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static byte[] ReadEncryptedMessage(Stream inputStream, SymmetricAlgorithm aes)
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{
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using var inputReader = new BinaryReader(inputStream, Encoding.UTF8, true);
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using ICryptoTransform cryptoTransform = aes.CreateDecryptor();
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// read unencrypted length header
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using var buffer = new MemoryStream();
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int length = IPAddress.NetworkToHostOrder(inputReader.ReadInt32());
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Console.WriteLine($"Reading {length} bytes");
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buffer.Write(inputReader.ReadBytes(length));
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// read encrypted data
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Console.WriteLine($"Read {buffer.Length} bytes");
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Console.WriteLine("Decrypting...");
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buffer.Position = 0;
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using var cryptoStream = new CryptoStream(buffer, cryptoTransform, CryptoStreamMode.Read);
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using var gzip = new GZipStream(cryptoStream, CompressionMode.Decompress);
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using var cryptoReader = new BinaryReader(gzip, Encoding.UTF8);
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length = IPAddress.NetworkToHostOrder(cryptoReader.ReadInt32());
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Console.WriteLine($"Need to read {length} bytes");
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return cryptoReader.ReadBytes(length);
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}
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static void SendEncryptedMessage(byte[] message, Stream outputStream, SymmetricAlgorithm aes)
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{
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using var outputWriter = new BinaryWriter(outputStream, Encoding.UTF8, true);
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using ICryptoTransform cryptoTransform = aes.CreateEncryptor();
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// encrypt data
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using var buffer = new MemoryStream();
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using var cryptoStream = new CryptoStream(buffer, cryptoTransform, CryptoStreamMode.Write);
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using var gzip = new GZipStream(cryptoStream, CompressionMode.Compress);
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using var cryptoWriter = new BinaryWriter(gzip, Encoding.UTF8);
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cryptoWriter.Write(IPAddress.HostToNetworkOrder(message.Length));
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cryptoWriter.Write(message);
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cryptoWriter.Flush();
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cryptoStream.FlushFinalBlock();
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buffer.Position = 0;
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// sent encrypted data with unencrypted length header
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Console.WriteLine($"Writing {buffer.Length} bytes");
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outputWriter.Write(IPAddress.HostToNetworkOrder((int)BitOperations.RoundUpToPowerOf2((uint)buffer.Length)));
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buffer.CopyTo(outputStream);
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outputStream.Flush();
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Console.WriteLine("Message sent");
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}
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