import java.io.BufferedReader;
import java.io.Console;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import java.util.Arrays;
import java.util.Random;

import javax.crypto.Cipher;
import javax.crypto.CipherOutputStream;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;

public class MinecraftLoginEncrypter {
    public static void main(String[] args) throws IOException {
        System.err.println("Security Note: Please check that this program has not been modified to harvest your login before inputting your username-password combination. In the source, look for \"java.net\"; in the binary, look for \"Ljava/net\" in a hex editor.");
        BufferedReader keyboardLines = new BufferedReader(new InputStreamReader(System.in));
        System.err.print("Username: ");
        String user = keyboardLines.readLine();
        char[] pass = null;
        try {
            Console console = System.console();
            if (console != null) {
                System.err.print("Password: ");
                pass = console.readPassword();
            }
        } catch (NoClassDefFoundError ncdfe) {
            // pass = null;
        } catch (NoSuchMethodError nsme) {
            // pass = null;
        }
        if (pass == null) {
            System.err.println("Security Note: No password-hiding functionality is available in this Java VM. The following password prompt will SHOW the password you enter.");
            System.err.print("Password: ");
            pass = keyboardLines.readLine().toCharArray();
        }
        MinecraftLoginEncrypter encrypter = new MinecraftLoginEncrypter(user, pass);
        try {
            encrypter.writeFile(new File(".", "lastlogin"));
            System.err.println("File written.");
        } finally {
            encrypter.close();
        }
    }

    private final String user;

    private final char[] pass;

    public MinecraftLoginEncrypter(final String user, final char[] pass) {
        this.user = user;
        this.pass = pass;
    }

    public void writeFile(File file) throws IOException {
        Cipher cipher;
        try {
            cipher = getCipher(Cipher.ENCRYPT_MODE, "passwordfile");
        } catch (Exception e) {
            throw new IOException("Error occurred while creating the cipher for the Minecraft login file", e);
        }
        DataOutputStream dos;
        if (cipher != null)
            dos = new DataOutputStream(new CipherOutputStream(new FileOutputStream(file), cipher));
        else {
            dos = new DataOutputStream(new FileOutputStream(file));
        }
        dos.writeUTF(user);
        CharsetEncoder c = Charset.forName("UTF-8").newEncoder();
        ByteBuffer bb = ByteBuffer.allocate(pass.length * (int) Math.ceil(c.maxBytesPerChar()));
        try {
            c.encode(CharBuffer.wrap(pass), bb, true);
            c.reset();
            dos.writeShort(bb.position());
            bb.flip();
            byte[] passBytes = new byte[bb.remaining()];
            try {
                bb.get(passBytes);
                dos.write(passBytes);
            } finally {
                // Avoid memory sniffing attacks: zero out the password
                Arrays.fill(passBytes, (byte) 0);
            }
        } finally {
            bb.clear();
            // Avoid memory sniffing attacks: zero out the password
            for (int i = 0; i < bb.limit(); i++) {
                bb.put(i, (byte) 0);
            }
        }
        dos.flush();
        dos.close();
    }

    public void close() {
        // Avoid memory sniffing attacks: zero out the password
        Arrays.fill(pass, '\0');
    }

    protected void finalize() throws Throwable {
        close();
    }

    private Cipher getCipher(int mode, String password) throws InvalidKeySpecException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException {
        Random random = new Random(43287234L);
        byte[] salt = new byte[8];
        random.nextBytes(salt);
        PBEParameterSpec pbeParamSpec = new PBEParameterSpec(salt, 5);

        SecretKey pbeKey = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(new PBEKeySpec(password.toCharArray()));
        Cipher cipher = Cipher.getInstance("PBEWithMD5AndDES");
        cipher.init(mode, pbeKey, pbeParamSpec);
        return cipher;
    }
}