/**
* Attempts to log a client in using the authentication server. Authentication server needs to run
* on the same host as the file server.
*
* @throws IOException Error reading from socket.
*/
private void login() throws IOException {
// set up required variables
DatagramSocket clientSocket = new DatagramSocket();
InetAddress authServerIP =
InetAddress
.getLocalHost(); // because authentication server runs on same host as file server
byte[] dataToSend;
byte[] receivedData = new byte[BUFFER_SIZE];
// get username and password
String userName = inFromClient.readLine().trim(); // get username
String password = inFromClient.readLine().trim(); // get password
dataToSend = new String(userName + " " + password).getBytes();
// send the username and password for processing by authentication server
DatagramPacket packetToSend =
new DatagramPacket(dataToSend, dataToSend.length, authServerIP, AUTHENTICATION_PORT);
clientSocket.send(packetToSend);
// receive the response from the authentication server
DatagramPacket receivedPacket = new DatagramPacket(receivedData, receivedData.length);
clientSocket.receive(receivedPacket);
String receivedString = new String(receivedPacket.getData()).trim();
receivedData = receivedString.getBytes();
if (receivedString.equals("yes")) {
outToClient.writeBytes(receivedString); // successful login
} else {
outToClient.writeBytes("no"); // unsuccessful login
}
}
public void run() // loop utama, utk nerima user input n kirim ke server&client laen
{
while (thread != null) {
try {
String a = console.readLine();
String b = cryptor.encrypt(a);
streamOut.writeUTF(cryptor.encrypt(a));
streamOut.flush();
} catch (IOException ioe) {
System.out.println("Sending error: " + ioe.getMessage());
stop();
}
}
}
/** Sends the user a list of the files contained in the same folder as the server. */
private void listFiles() throws IOException {
File folder = new File(".");
File[] listOfFiles = folder.listFiles();
for (File f : listOfFiles) {
outToClient.writeBytes(f.getName() + '\n');
}
}
public void stop() {
if (thread != null) {
thread.stop();
thread = null;
}
try {
if (console != null) console.close();
if (streamOut != null) streamOut.close();
if (socket != null) socket.close();
} catch (IOException ioe) {
System.out.println("Error closing ...");
}
client.close();
client.stop();
}
public static void main(String[] args) throws Exception {
// prompt user to enter a port number
System.out.print("Enter the port number: ");
Scanner scan = new Scanner(System.in);
int port = scan.nextInt();
scan.nextLine();
System.out.print("Enter the host name: ");
String hostName = scan.nextLine();
// Initialize a key pair generator with the SKIP parameters we sepcified, and genrating a pair
// This will take a while: 5...15 seconrds
System.out.println("Generating a Diffie-Hellman keypair: ");
KeyPairGenerator kpg = KeyPairGenerator.getInstance("DH");
kpg.initialize(PARAMETER_SPEC);
KeyPair keyPair = kpg.genKeyPair();
System.out.println("key pair has been made...");
// one the key pair has been generated, we want to listen on
// a given port for a connection to come in
// once we get a connection, we will get two streams, One for input
// and one for output
// open a port and wait for a connection
ServerSocket ss = new ServerSocket(port);
System.out.println("Listeining on port " + port + " ...");
Socket socket = ss.accept();
// use to output and input primitive data type
DataOutputStream out = new DataOutputStream(socket.getOutputStream());
// next thing to do is send our public key and receive client's
// this corresponds to server step 3 and step 4 in the diagram
System.out.println("Sending my public key...");
byte[] keyBytes = keyPair.getPublic().getEncoded();
out.writeInt(keyBytes.length);
out.write(keyBytes);
System.out.println("Server public key bytes: " + CryptoUtils.toHex(keyBytes));
// receive the client's public key
System.out.println("Receiving client's public key...");
DataInputStream in = new DataInputStream(socket.getInputStream());
keyBytes = new byte[in.readInt()];
in.readFully(keyBytes);
// create client's public key
KeyFactory kf = KeyFactory.getInstance("DH");
X509EncodedKeySpec x509Spec = new X509EncodedKeySpec(keyBytes);
PublicKey clientPublicKey = kf.generatePublic(x509Spec);
// print out client's public key bytes
System.out.println(
"Client public key bytes: " + CryptoUtils.toHex(clientPublicKey.getEncoded()));
// we can now use the client's public key and
// our own private key to perform the key agreement
System.out.println("Performing the key agreement ... ");
KeyAgreement ka = KeyAgreement.getInstance("DH");
ka.init(keyPair.getPrivate());
ka.doPhase(clientPublicKey, true);
// in a chat application, each character is sendt over the wire, separetly encrypted,
// Instead of using ECB, we are goin to use CFB, with a block size of 8 bits(1byte)
// to send each character. We will encrypt the same character in a different way
// each time. But in order to use CFB8, we need an IVof 8 bytes. We will create
// that IV randomly and and send it to the client. It doesn't matter if somoene
// eavesdrops on the IV when it is sent over the wire. it's not sensitive info
// creating the IV and sending it corresponds to step 6 and 7
byte[] iv = new byte[8];
SecureRandom sr = new SecureRandom();
sr.nextBytes(iv);
out.write(iv);
// we generate the secret byte array we share with the client and use it
// to create the session key (Step 8)
byte[] sessionKeyBytes = ka.generateSecret();
// create the session key
SecretKeyFactory skf = SecretKeyFactory.getInstance("DESede");
DESedeKeySpec DESedeSpec = new DESedeKeySpec(sessionKeyBytes);
SecretKey sessionKey = skf.generateSecret(DESedeSpec);
// printout session key bytes
System.out.println("Session key bytes: " + CryptoUtils.toHex(sessionKey.getEncoded()));
// now use tha that session key and IV to create a CipherInputStream. We will use them to read
// all character
// that are sent to us by the client
System.out.println("Creating the cipher stream ...");
Cipher decrypter = Cipher.getInstance("DESede/CFB8/NoPadding");
IvParameterSpec spec = new IvParameterSpec(iv);
decrypter.init(Cipher.DECRYPT_MODE, sessionKey, spec);
CipherInputStream cipherIn = new CipherInputStream(socket.getInputStream(), decrypter);
// we just keep reading the input and print int to the screen, until -1 sent over
int theCharacter = 0;
theCharacter = cipherIn.read();
while (theCharacter != -1) {
System.out.print((char) theCharacter);
theCharacter = cipherIn.read();
}
// once -1 is received we want to close up our stream and exit
cipherIn.close();
in.close();
out.close();
socket.close();
}
public static void main(String[] args) {
try {
if (args[0].equals("-genkey")) {
KeyPairGenerator pairgen = KeyPairGenerator.getInstance("RSA");
SecureRandom random = new SecureRandom();
pairgen.initialize(KEYSIZE, random);
KeyPair keyPair = pairgen.generateKeyPair();
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(args[1]));
out.writeObject(keyPair.getPublic());
out.close();
out = new ObjectOutputStream(new FileOutputStream(args[2]));
out.writeObject(keyPair.getPrivate());
out.close();
} else if (args[0].equals("-encrypt")) {
KeyGenerator keygen = KeyGenerator.getInstance("AES");
SecureRandom random = new SecureRandom();
keygen.init(random);
SecretKey key = keygen.generateKey();
// wrap with RSA public key
ObjectInputStream keyIn = new ObjectInputStream(new FileInputStream(args[3]));
Key publicKey = (Key) keyIn.readObject();
keyIn.close();
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.WRAP_MODE, publicKey);
byte[] wrappedKey = cipher.wrap(key);
DataOutputStream out = new DataOutputStream(new FileOutputStream(args[2]));
out.writeInt(wrappedKey.length);
out.write(wrappedKey);
InputStream in = new FileInputStream(args[1]);
cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, key);
crypt(in, out, cipher);
in.close();
out.close();
} else {
DataInputStream in = new DataInputStream(new FileInputStream(args[1]));
int length = in.readInt();
byte[] wrappedKey = new byte[length];
in.read(wrappedKey, 0, length);
// unwrap with RSA private key
ObjectInputStream keyIn = new ObjectInputStream(new FileInputStream(args[3]));
Key privateKey = (Key) keyIn.readObject();
keyIn.close();
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.UNWRAP_MODE, privateKey);
Key key = cipher.unwrap(wrappedKey, "AES", Cipher.SECRET_KEY);
OutputStream out = new FileOutputStream(args[2]);
cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, key);
crypt(in, out, cipher);
in.close();
out.close();
}
} catch (IOException e) {
e.printStackTrace();
} catch (GeneralSecurityException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}