Minecraft Wiki
Advertisement

Random Code

I hereby release all of my rights to the code contained within this section.

Finding .minecraft (Java)

static final File getMinecraftWorkingDir() {
	String home = System.getProperty("user.home", ".");
	String os = System.getProperty("os.name").toLowerCase();
	if (os.contains("solaris") || os.contains("sunos")
	    || os.contains("linux") || os.contains("unix"))
		return new File(home, ".minecraft/");
	else if (os.contains("win")) {
		String appdata = System.getenv("APPDATA");
		return new File(appdata != null ? appdata : home, ".minecraft/");
	} else if (os.contains("mac"))
		return new File(home, "Library/Application Support/minecraft/");
	return new File(home, "minecraft/");
}

Reading lastlog File (Java)

Cipher.getInstance is expensive, so here it is only called once and the result is stored as a static final.

To load user data from a file: load(File file);

To save user data to a file: save(new UserData(String username, String password);

To get the default lastlogin file, use: new File(getMinecraftWorkingDir(), "lastlogin");

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
private static final Key             key       = new SecretKeySpec(
                                                   new byte[] {
    (byte) 0xd8, (byte) 0x08, (byte) 0x77, (byte) 0xe7, (byte) 0x61,
    (byte) 0xac, (byte) 0xd9, (byte) 0x1d         }, "DES");
private static final IvParameterSpec paramspec = new IvParameterSpec(
                                                   new byte[] {
    (byte) 0xc0, (byte) 0x05, (byte) 0x86, (byte) 0x92, (byte) 0xec,
    (byte) 0x67, (byte) 0xcf, (byte) 0x39         });
private static final Cipher          cipher    = getCipher();

private static final Cipher getCipher() {
	try {
		return Cipher.getInstance("DES/CBC/PKCS5Padding");
	} catch (NoSuchAlgorithmException | NoSuchPaddingException e) {}
	return null;
}

private static synchronized boolean initCipher(final int mode) {
	try {
		cipher.init(mode, key, paramspec);
		return true;
	} catch (InvalidKeyException | InvalidAlgorithmParameterException
	    | NullPointerException e) {}
	return false;
}

public static synchronized UserData load(final File file)
    throws IOException {
	@SuppressWarnings("resource")
	final DataInputStream dis = new DataInputStream(
	    initCipher(Cipher.DECRYPT_MODE)
	        ? new CipherInputStream(new FileInputStream(file), cipher)
	        : new FileInputStream(file));
	final UserData data = new UserData(dis.readUTF(), dis.readUTF());
	dis.close();
	return data;
}

public static synchronized void save(final File file, final UserData data)
    throws IOException {
	final DataOutputStream dos = new DataOutputStream(
	    initCipher(Cipher.ENCRYPT_MODE)
	        ? new CipherOutputStream(new FileOutputStream(file), cipher)
	        : new FileOutputStream(file));
	dos.writeUTF(data.username);
	dos.writeUTF(data.password);
	dos.close();
}
Advertisement