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Mar 24th, 2023
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  1. import java.io.IOException;
  2. import java.net.ServerSocket;
  3. import java.net.Socket;
  4. import java.security.*;
  5. import java.security.spec.InvalidKeySpecException;
  6. import java.security.spec.X509EncodedKeySpec;
  7. import java.util.Arrays;
  8. import javax.crypto.*;
  9. import javax.crypto.spec.*;
  10. import org.bouncycastle.jce.provider.BouncyCastleProvider;
  11. import org.bouncycastle.util.encoders.Hex;
  12.  
  13. public class SecureRelayServer {
  14. private static final int SERVER_PORT = 8080;
  15.  
  16. public static void main(String[] args) throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException, InvalidKeySpecException, SignatureException {
  17. Security.addProvider(new BouncyCastleProvider());
  18.  
  19. // Generate server key pair
  20. KeyPair serverKeyPair = generateKeyPair();
  21.  
  22. // Set up server socket
  23. ServerSocket serverSocket = new ServerSocket(SERVER_PORT);
  24. System.out.println("Server started on port " + SERVER_PORT);
  25.  
  26. while (true) {
  27. Socket clientSocket1 = serverSocket.accept();
  28. System.out.println("Client connected: " + clientSocket1.getInetAddress().getHostName());
  29.  
  30. // Perform X25519+Ed25519 key exchange with client
  31. KeyPair clientKeyPair = performKeyExchange(clientSocket1, serverKeyPair.getPrivate(), serverKeyPair.getPublic());
  32.  
  33. // Set up encryption keys
  34. SecretKey encryptionKey1 = generateEncryptionKey(clientKeyPair.getPrivate(), serverKeyPair.getPublic());
  35. SecretKey encryptionKey2 = generateEncryptionKey(serverKeyPair.getPrivate(), clientKeyPair.getPublic());
  36.  
  37. // Start relaying data
  38. new Thread(() -> relayData(clientSocket1, encryptionKey1, encryptionKey2)).start();
  39. }
  40. }
  41.  
  42. private static void relayData(Socket fromSocket, SecretKey encryptionKey1, SecretKey encryptionKey2) {
  43. try {
  44. // Set up cipher for encryption/decryption
  45. Cipher cipher = Cipher.getInstance("ChaCha20-Poly1305");
  46. cipher.init(Cipher.ENCRYPT_MODE, encryptionKey1);
  47.  
  48. byte[] buffer = new byte[1024];
  49. int bytesRead;
  50. while ((bytesRead = fromSocket.getInputStream().read(buffer)) != -1) {
  51. byte[] encrypted = cipher.update(Arrays.copyOfRange(buffer, 0, bytesRead));
  52. System.out.println("Encrypted: " + Hex.toHexString(encrypted));
  53. // Relay encrypted data to other socket
  54. // ...
  55. }
  56.  
  57. // Finish encryption and relay final data
  58. byte[] encrypted = cipher.doFinal();
  59. System.out.println("Encrypted: " + Hex.toHexString(encrypted));
  60. // Relay encrypted data to other socket
  61. // ...
  62.  
  63. } catch (IOException | NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException e) {
  64. e.printStackTrace();
  65. } finally {
  66. try {
  67. fromSocket.close();
  68. // Close other socket
  69. // ...
  70. } catch (IOException e) {
  71. e.printStackTrace();
  72. }
  73. }
  74. }
  75.  
  76. private static KeyPair generateKeyPair() throws NoSuchAlgorithmException {
  77. KeyPairGenerator keyGen = KeyPairGenerator.getInstance("Ed25519");
  78. return keyGen.generateKeyPair();
  79. }
  80.  
  81. private static KeyPair performKeyExchange(Socket clientSocket, PrivateKey privateKey, PublicKey publicKey) throws NoSuchAlgorithmException, NoSuchProviderException, InvalidAlgorithmParameterException, InvalidKeyException, SignatureException, IOException, InvalidKeySpecException {
  82. // Generate ECDH key pair
  83. KeyPairGenerator keyGen = KeyPairGenerator.getInstance("X25519");
  84. KeyPair keyPair = keyGen.generateKeyPair();
  85.  
  86. // Send public key to client
  87.  
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