Password dialog and flexible encryption

Added a password dialog
Split encryption into byte-array and hex-encoded string in- and outputs.

data/accounts.json

@@ -1 +0,0 @@
-[{"firstName":"Dank","lastName":"Memes","history":[{"balanceChange":230,"description":"User deposited 230.0."},{"balanceChange":-12,"description":"User withdrew 12.0."},{"balanceChange":321,"description":"Received 321.0 from Meme Lord."}],"accountNumber":"123456789"},{"firstName":"Meme","lastName":"Lord","history":[{"balanceChange":10000,"description":"User deposited 10000.0."},{"balanceChange":-2103,"description":"User withdrew 2103.0."},{"balanceChange":-321,"description":"Transferred 321.0 to Dank Memes."}],"accountNumber":"987654321"}]

data/backup.json

@@ -1 +0,0 @@
-[{"firstName":"Dank","lastName":"Memes","history":[{"balanceChange":230,"description":"User deposited 230.0."},{"balanceChange":-12,"description":"User withdrew 12.0."}],"accountNumber":"123456789"},{"firstName":"Meme","lastName":"Lord","history":[{"balanceChange":10000,"description":"User deposited 10000.0."},{"balanceChange":-2103,"description":"User withdrew 2103.0."},{"balanceChange":-123,"description":"Transferred 123.0 to K Kman."}],"accountNumber":"987654321"},{"firstName":"Triggered","lastName":"Meme","history":[{"balanceChange":200032,"description":"User deposited 200032.0."},{"balanceChange":2,"description":"User deposited 2.0."}],"accountNumber":"719803"},{"firstName":"K","lastName":"Kman","history":[{"balanceChange":123145,"description":"User deposited 123145.0."},{"balanceChange":-23,"description":"User withdrew 23.0."},{"balanceChange":123,"description":"Received 123.0 from Meme Lord."}],"accountNumber":"105492"}]

src/eu/tankernn/accounts/AccountManager.java

@@ -15,12 +15,16 @@ import org.json.JSONException;
 import org.json.JSONObject;
 
 import eu.tankernn.accounts.frame.MainFrame;
+import eu.tankernn.accounts.frame.PasswordDialog;
 import eu.tankernn.accounts.util.Encryption;
+import eu.tankernn.accounts.util.InvalidPasswordException;
 
 public class AccountManager {
+	public static final String CURRENCY = "SEK";
+
 	private static String lastJSONString = "[]";
-	private static String lastPassword;
-	private static boolean saveWithEncryption = false;
+	private static char[] lastPassword;
+	private static boolean saveWithEncryption = true;
 
 	private static List<Account> accounts;
 
@@ -41,45 +45,59 @@ public class AccountManager {
 	}
 
 	public static void openFile() {
-		openFile(null);
+		FileManager.FILE_CHOOSER.showOpenDialog(null);
+		openFile(FileManager.FILE_CHOOSER.getSelectedFile());
 	}
 
 	/**
-	 * Loads the account file specified.
+	 * Loads the accounts in the file specified.
 	 * 
 	 * @param file
 	 *            The file to load
 	 */
 	public static void openFile(File file) {
-		String rawString = null;
+		// Open plain text file
 		try {
-			rawString = FileManager.readFileAsString(file);
+			String jsonString = FileManager.readFileAsString(file);
+			//If '[' is first, the JSON is *probably* valid
+			if (jsonString.startsWith("[")) {
+				accounts = parseJSON(jsonString);
+				lastJSONString = jsonString;
+				return;
+			}
 		} catch (IOException e) {
 			e.printStackTrace();
 			return;
 		}
-		if (rawString != null) {
-			String password = null;
-			String jsonString = new String(rawString);
-			while (true) {
-				try {
-					jsonString = password == null ? new String(rawString) : Encryption.decrypt(rawString, password);
-					accounts = parseJSON(jsonString);
-					lastPassword = password;
-					break;
-				} catch (JSONException e) {
-					if (e.getMessage().startsWith("A JSONArray text must start with '['")) {
-						e.printStackTrace();
-						password = JOptionPane.showInputDialog("Invalid JSON, try decrypting it with a password.");
-					} else {
-						e.printStackTrace();
-						break;
-					}
+		// Open encrypted file
+		byte[][] data = null; 
+		try {
+			data = FileManager.readObjectFromFile(file, byte[][].class);
+		} catch (IOException e) {
+			e.printStackTrace();
+			return;
+		} catch (ClassNotFoundException e) {
+			e.printStackTrace();
+			return;
+		}
+		String jsonString = new String();
+		do {
+			try {
+				char[] password = PasswordDialog
+						.showPasswordDialog("The data is encrypted, please enter the password to decrypt it.");
+				if (password == null) {
+					// Start the program without loading a file
+					return;
 				}
+				jsonString = Encryption.decrypt(data, password);
+				lastPassword = password;
+				break;
+			} catch (InvalidPasswordException e) {
+				continue;
 			}
-			lastJSONString = jsonString;
-		} else
-			accounts = new ArrayList<Account>();
+		} while (jsonString.toCharArray()[0] != '[');
+		accounts = parseJSON(jsonString);
+		lastJSONString = jsonString;
 		window.refresh();
 	}
 
@@ -112,17 +130,20 @@ public class AccountManager {
 	public static void saveFile(boolean saveAs) {
 		try {
 			String newData = exportJSON();
-			String encryptedData = null;
+			byte[][] encryptedData = null;
 			if (saveWithEncryption) {
-				while (lastPassword == null || lastPassword.isEmpty()) {
-					lastPassword = JOptionPane.showInputDialog("Select a password to encrypt the account file with.");
+				while (lastPassword == null || lastPassword.length < 5) {
+					lastPassword = PasswordDialog
+							.showPasswordDialog("Select a password to encrypt the account file with. (At least 5 characters, preferrably longer)");
 				}
 				encryptedData = Encryption.encrypt(newData, lastPassword);
 			}
-
-			FileManager.writeStringToFile(saveAs, encryptedData == null ? newData : encryptedData);
+			if (encryptedData == null)
+				FileManager.writeStringToFile(saveAs, newData);
+			else
+				FileManager.writeObjectToFile(saveAs, encryptedData);
 			lastJSONString = newData;
-		} catch (FileNotFoundException e1) {
+		} catch (ClassNotFoundException | IOException e1) {
 			e1.printStackTrace();
 		}
 	}
@@ -130,7 +151,8 @@ public class AccountManager {
 	/**
 	 * Asks the user to save the current file if any changes have been made.
 	 * 
-	 * @return <code>false</code> if the user clicked cancel. True otherwise.
+	 * @return <code>false</code> if the user clicked cancel. <code>true</code>
+	 *         otherwise.
 	 */
 	public static boolean closeFile() {
 		if (!AccountManager.hasUnsavedChanges()) {
@@ -175,7 +197,6 @@ public class AccountManager {
 		JSONArray jsonArr = new JSONArray();
 		for (Account a : accounts)
 			jsonArr.put(new JSONObject(a));
-		System.out.println(jsonArr.toString());
 		return jsonArr.toString();
 	}
 
@@ -194,10 +215,17 @@ public class AccountManager {
 		window.refresh();
 	}
 
+	/**
+	 * Searches the list of accounts for ones matching the search string by name
+	 * or account number.
+	 * 
+	 * @param s
+	 *            The search string
+	 * @return The list of matching accounts
+	 */
 	public static List<Account> search(String s) {
-		return Arrays.asList(accounts.stream()
-				.filter(a -> a.getAccountNumber().toLowerCase().contains(s) || a.toString().toLowerCase().contains(s))
-				.toArray(Account[]::new));
+		return Arrays.asList(accounts.stream().filter(a -> a.getAccountNumber().toLowerCase().contains(s.toLowerCase())
+				|| a.toString().toLowerCase().contains(s.toLowerCase())).toArray(Account[]::new));
 	}
 
 	public static List<Account> getAccounts() {
@@ -214,4 +242,12 @@ public class AccountManager {
 		return accounts.stream().filter(a -> a.getAccountNumber().equals(accountNumber)).findFirst();
 	}
 
+	public static boolean isSavingWithEncryption() {
+		return saveWithEncryption;
+	}
+
+	public static void setSaveWithEncryption(boolean saveWithEncryption) {
+		AccountManager.saveWithEncryption = saveWithEncryption;
+	}
+
 }

src/eu/tankernn/accounts/FileManager.java

@@ -2,16 +2,19 @@ package eu.tankernn.accounts;
 
 import java.io.BufferedReader;
 import java.io.File;
+import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.FileReader;
 import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
 
 import javax.swing.JFileChooser;
 import javax.swing.JOptionPane;
 
 public class FileManager {
-	private static final JFileChooser FILE_CHOOSER = new JFileChooser("data/");
+	public static final JFileChooser FILE_CHOOSER = new JFileChooser("data/");
 
 	private static final File lastFilenameCache = new File(
 			System.getProperty("user.home") + File.separator + "accountmanager" + File.separator + "lastFile.txt");
@@ -42,7 +45,7 @@ public class FileManager {
 		// Remember this filename
 		if (!file.equals(lastFilenameCache))
 			FileManager.writeStringToFile(lastFilenameCache, file.getAbsolutePath());
-		
+
 		BufferedReader reader = new BufferedReader(new FileReader(file));
 		StringBuilder builder = new StringBuilder();
 
@@ -71,15 +74,15 @@ public class FileManager {
 			JOptionPane.showMessageDialog(null, "That file already exists.");
 			return null;
 		}
-		
+
 		newFile.createNewFile();
-		
+
 		FileManager.writeStringToFile(lastFilenameCache, newFile.getAbsolutePath());
 		writeStringToFile(newFile, "[]");
 
 		return newFile;
 	}
-	
+
 	public static void writeStringToFile(boolean saveAs, String contents) throws FileNotFoundException {
 		if (saveAs)
 			FILE_CHOOSER.showSaveDialog(null);
@@ -111,4 +114,27 @@ public class FileManager {
 	public static File latestFile() {
 		return FILE_CHOOSER.getSelectedFile();
 	}
+
+	public static <T> T readObjectFromFile(File file, Class<T> class1) throws IOException, ClassNotFoundException {
+		if (file == null) {
+			FILE_CHOOSER.showOpenDialog(null);
+			file = FILE_CHOOSER.getSelectedFile();
+		}
+		ObjectInputStream in = new ObjectInputStream(new FileInputStream(file));
+		T obj = class1.cast(in.readObject());
+		in.close();
+		return obj;
+	}
+
+	public static <T> void writeObjectToFile(boolean saveAs, T contents) throws ClassNotFoundException, IOException {
+		if (saveAs)
+			FILE_CHOOSER.showSaveDialog(null);
+		writeObjectToFile(saveAs ? FILE_CHOOSER.getSelectedFile() : getLastFileFromCache(), contents);
+	}
+
+	public static <T> void writeObjectToFile(File file, T obj) throws IOException, ClassNotFoundException {
+		ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(file));
+		out.writeObject(obj);
+		out.close();
+	}
 }

src/eu/tankernn/accounts/frame/AccountPanel.java

@@ -5,6 +5,7 @@ import java.awt.Dimension;
 import java.awt.GridLayout;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
+import java.text.DecimalFormat;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -22,6 +23,7 @@ import javax.swing.border.TitledBorder;
 import eu.tankernn.accounts.Account;
 import eu.tankernn.accounts.AccountEvent;
 import eu.tankernn.accounts.AccountManager;
+import eu.tankernn.accounts.util.GUIUtils;
 
 public class AccountPanel extends JPanel implements ActionListener {
 
@@ -32,6 +34,8 @@ public class AccountPanel extends JPanel implements ActionListener {
 
 	private Account currentAccount;
 
+	private DecimalFormat format;
+
 	private JPanel infoPanel = new JPanel();
 	private JLabel lName = new JLabel("Name: "), lBalance = new JLabel("Balance: "),
 			lAccountNumber = new JLabel("Account number: ");
@@ -50,6 +54,10 @@ public class AccountPanel extends JPanel implements ActionListener {
 	public AccountPanel() {
 		this.setLayout(new BorderLayout());
 
+		format = new DecimalFormat("### ###.00");
+		format.setGroupingUsed(true);
+		format.setGroupingSize(3);
+
 		infoPanel.setLayout(new GridLayout(6, 1));
 		add(infoPanel, BorderLayout.WEST);
 		infoPanel.add(lName);
@@ -71,33 +79,33 @@ public class AccountPanel extends JPanel implements ActionListener {
 
 	public void updatePanel(Account a) {
 		this.currentAccount = a;
-		
+
 		if (a == null) {
 			lName.setText("Name: ");
 			lBalance.setText("Balance: ");
 			lAccountNumber.setText("Account number: ");
 			history.setModel(new DefaultListModel<AccountEvent>());
-			
+
 			transferFrom.setEnabled(false);
 			deposit.setEnabled(false);
 			withdraw.setEnabled(false);
 		} else {
 			lName.setText("Name: " + a.toString());
-			lBalance.setText("Balance: " + a.calculateBalance());
+			lBalance.setText("Balance: " + AccountManager.CURRENCY + " " + format.format(a.calculateBalance()));
 			lAccountNumber.setText("Account number: " + a.getAccountNumber());
 			history.setModel(GUIUtils.listModelFromList(a.getHistory()));
-			
+
 			// "Clone" account list
 			List<Account> accounts = new ArrayList<Account>(AccountManager.getAccounts());
 			// Can't transfer to self
 			accounts.remove(a);
 			otherAccounts.setModel(GUIUtils.comboBoxModelFromList(accounts));
-			
+
 			transferFrom.setEnabled(true);
 			deposit.setEnabled(true);
 			withdraw.setEnabled(true);
 		}
-		
+
 		// Fix history list width.
 		Dimension d = scrollPane.getPreferredSize();
 		d.width = infoPanel.getWidth(); // Same as infopanel
@@ -117,7 +125,8 @@ public class AccountPanel extends JPanel implements ActionListener {
 			}
 
 			JOptionPane.showConfirmDialog(null,
-					new JComponent[] { new JLabel("Please select receiver account."), otherAccounts }, "Select account.", JOptionPane.DEFAULT_OPTION, JOptionPane.PLAIN_MESSAGE);
+					new JComponent[] { new JLabel("Please select receiver account."), otherAccounts },
+					"Select account.", JOptionPane.DEFAULT_OPTION, JOptionPane.PLAIN_MESSAGE);
 
 			Account sender = currentAccount, receiver = (Account) otherAccounts.getSelectedItem();
 
@@ -138,11 +147,14 @@ public class AccountPanel extends JPanel implements ActionListener {
 			if (amount < 0) {
 				JOptionPane.showMessageDialog(this, "Please enter a positive value.");
 				return;
+			} else if (amount > currentAccount.calculateBalance()) {
+				JOptionPane.showMessageDialog(this, "You do not have enough balance to withdraw that amount.");
+				return;
 			}
 
 			currentAccount.getHistory().add(new AccountEvent(-amount, "User withdrew " + amount + "."));
 		}
-		
+
 		this.updatePanel(currentAccount);
 	}
 
@@ -150,11 +162,12 @@ public class AccountPanel extends JPanel implements ActionListener {
 		String amountStr = JOptionPane.showInputDialog("Amount to " + action + ":");
 
 		double amount = -1;
-		try {
-			amount = Double.parseDouble(amountStr);
-		} catch (NumberFormatException ex) {
-			JOptionPane.showMessageDialog(null, "Please enter a valid number value.");
-		}
+		while (amount == -1)
+			try {
+				amount = Double.parseDouble(amountStr);
+			} catch (NumberFormatException ex) {
+				JOptionPane.showMessageDialog(null, "Please enter a valid number value.");
+			}
 		return amount;
 	}
 }

src/eu/tankernn/accounts/frame/MainFrame.java

@@ -20,13 +20,14 @@ import javax.swing.event.ListSelectionListener;
 import eu.tankernn.accounts.Account;
 import eu.tankernn.accounts.AccountManager;
 import eu.tankernn.accounts.frame.menu.MainMenuBar;
+import eu.tankernn.accounts.util.GUIUtils;
 
 public class MainFrame implements ListSelectionListener, DocumentListener {
 	
 	private JFrame frame;
 	private LayoutManager manager;
 	
-	// Graphics components
+	// GUI components
 	
 	private MainMenuBar menubar;
 	
@@ -70,18 +71,22 @@ public class MainFrame implements ListSelectionListener, DocumentListener {
 	private void initialize() {
 		manager = new BorderLayout();
 		menubar = new MainMenuBar(this);
-		search = new JTextField();
+		search = new JTextField("Search...");
 		accounts = new JList<Account>();
 		
 		frame = new JFrame();
 		frame.setLayout(manager);
 		frame.setJMenuBar(menubar);
 		
+		listPanel = new JPanel();
+		listPanel.setLayout(new BorderLayout());
 		search.getDocument().addDocumentListener(this);
+		listPanel.add(search, BorderLayout.NORTH);
 		accounts.addListSelectionListener(this);
 		accountScrollPane = new JScrollPane(accounts);
 		accountScrollPane.setPreferredSize(new Dimension(100, 100));
-		frame.add(accountScrollPane, BorderLayout.WEST);
+		listPanel.add(accountScrollPane, BorderLayout.CENTER);
+		frame.add(listPanel, BorderLayout.WEST);
 		
 		
 		accountPanel = new AccountPanel();

src/eu/tankernn/accounts/frame/PasswordDialog.java

@@ -0,0 +1,31 @@
+package eu.tankernn.accounts.frame;
+
+import javax.swing.JComponent;
+import javax.swing.JLabel;
+import javax.swing.JOptionPane;
+import javax.swing.JPasswordField;
+
+public class PasswordDialog {
+	
+	private JLabel label = new JLabel();
+	private JPasswordField password;
+	private int result;
+
+	/**
+	 * Create the dialog.
+	 */
+	private PasswordDialog(String message) {
+		this.label.setText(message);
+		password = new JPasswordField();
+		result = JOptionPane.showConfirmDialog(null, new JComponent[] {label, password}, "Enter password", JOptionPane.OK_CANCEL_OPTION);
+	}
+	
+	public static char[] showPasswordDialog(String message) {
+		PasswordDialog dialog = new PasswordDialog(message);
+		if (dialog.result == JOptionPane.OK_OPTION)
+			return dialog.password.getPassword();
+		else
+			return null;
+	}
+
+}

src/eu/tankernn/accounts/frame/menu/MainMenuBar.java

@@ -5,6 +5,7 @@ import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.awt.event.KeyEvent;
 
+import javax.swing.JCheckBoxMenuItem;
 import javax.swing.JMenu;
 import javax.swing.JMenuBar;
 import javax.swing.JMenuItem;
@@ -32,7 +33,10 @@ public class MainMenuBar extends JMenuBar implements ActionListener {
 
 	private JMenu accountMenu = new JMenu("Accounts");
 	private JMenuItem newAccount = new JMenuItem("New account..."), refresh = new JMenuItem("Refresh accounts");
-
+	
+	private JMenu optionsMenu = new JMenu("Options");
+	private JCheckBoxMenuItem useEncryption = new JCheckBoxMenuItem("Use encryption when saving files");
+	
 	public MainMenuBar(MainFrame frame) {
 		this.frame = frame;
 		
@@ -46,7 +50,10 @@ public class MainMenuBar extends JMenuBar implements ActionListener {
 
 		// Accounts menu
 		addMenuWithItems(accountMenu, newAccount, refresh);
-
+		
+		// Options menu
+		addMenuWithItems(optionsMenu, useEncryption);
+		useEncryption.setSelected(AccountManager.isSavingWithEncryption());
 	}
 
 	private void addMenuWithItems(JMenu menu, JMenuItem... items) {
@@ -78,6 +85,8 @@ public class MainMenuBar extends JMenuBar implements ActionListener {
 			}
 		} else if (src.equals(refresh)) {
 			frame.refresh();
+		} else if (src.equals(useEncryption)) {
+			AccountManager.setSaveWithEncryption(useEncryption.isSelected());
 		}
 	}
 

src/eu/tankernn/accounts/util/Encryption.java

@@ -9,6 +9,7 @@ import java.security.SecureRandom;
 import java.security.spec.InvalidKeySpecException;
 import java.security.spec.InvalidParameterSpecException;
 import java.security.spec.KeySpec;
+import java.util.Arrays;
 
 import javax.crypto.BadPaddingException;
 import javax.crypto.Cipher;
@@ -21,46 +22,63 @@ import javax.crypto.spec.PBEKeySpec;
 import javax.crypto.spec.SecretKeySpec;
 
 public class Encryption {
-	
+
 	private static final String CIPHER_TYPE = "AES/GCM/PKCS5Padding";
-	private static final String STRING_SEPARATOR = "#";
-	
+	public static final String HEX_STRING_SEPARATOR = "#";
+
+	public static String decryptHexEncoded(String dataString, char[] password) throws InvalidPasswordException {
+		String[] splitted = dataString.split(HEX_STRING_SEPARATOR);
+		
+		byte[][] encryptedComplex = (byte[][]) Arrays.asList(splitted).stream().map(s -> hexToBytes(s)).toArray();
+
+		return decrypt(encryptedComplex, password);
+	}
+
 	/**
 	 * Decrypts an encrypted string of data.
 	 * 
-	 * @param dataString
+	 * @param data
 	 *            A hex-coded string with the format 'SALT#IV#DATA'
 	 * @param password
 	 *            The password used when the string was encoded
 	 * @return The decrypted string
+	 * @throws InvalidPasswordException
+	 *             if the password is incorrect
 	 */
-	public static String decrypt(String dataString, String password) {
-		String[] splitted = dataString.split(STRING_SEPARATOR);
-		
-		byte[] salt = hexToBytes(splitted[0]);
-		byte[] iv = hexToBytes(splitted[1]);
-		byte[] data = hexToBytes(splitted[2]);
+	public static String decrypt(byte[][] data, char[] password) throws InvalidPasswordException {
 
-		return decrypt(salt, iv, data, password);
+		return decrypt(data[0], data[1], data[2], password);
 	}
 
-	private static String decrypt(byte[] salt, byte[] iv, byte[] data, String key) {
+	private static String decrypt(byte[] salt, byte[] iv, byte[] data, char[] password)
+			throws InvalidPasswordException {
 		try {
-			SecretKey secret = composeKey(salt, key.toCharArray());
+			SecretKey secret = composeKey(salt, password);
 			Cipher cipher = Cipher.getInstance(CIPHER_TYPE);
-			
+
 			GCMParameterSpec params = new GCMParameterSpec(128, iv);
 			cipher.init(Cipher.DECRYPT_MODE, secret, params);
 			String plainText = new String(cipher.doFinal(data), "UTF-8");
 			return plainText;
 		} catch (InvalidKeyException | NoSuchAlgorithmException | NoSuchPaddingException | IllegalBlockSizeException
-				| BadPaddingException | InvalidKeySpecException | UnsupportedEncodingException
-				| InvalidAlgorithmParameterException e) {
+				| InvalidKeySpecException | UnsupportedEncodingException | InvalidAlgorithmParameterException e) {
 			e.printStackTrace();
 			return null;
+		} catch (BadPaddingException e) {
+			throw new InvalidPasswordException();
 		}
 	}
 
+	public static String encryptHexEncoded(String data, char[] password) {
+		byte[][] encryptedComplex = encrypt(data, password);
+
+		String saltString = bytesToHex(encryptedComplex[0]);
+		String ivString = bytesToHex(encryptedComplex[1]);
+		String dataString = bytesToHex(encryptedComplex[2]);
+
+		return String.join(HEX_STRING_SEPARATOR, saltString, ivString, dataString);
+	}
+
 	/**
 	 * Encrypts the data using a random salt.
 	 * 
@@ -69,35 +87,31 @@ public class Encryption {
 	 * @param password
 	 *            The password to use when decrypting the data.
 	 * @return All information needed to get the original data back, except the
-	 *         password, compiled into a single string.
+	 *         password.
 	 */
-	public static String encrypt(String data, String password) {
-		 byte[][] encryptedComplex = encrypt(new SecureRandom().generateSeed(8), data, password);
-		
-		String saltString = bytesToHex(encryptedComplex[0]);
-		String ivString = bytesToHex(encryptedComplex[1]);
-		String dataString = bytesToHex(encryptedComplex[2]);
-		
-		return String.join(STRING_SEPARATOR, saltString, ivString, dataString);
+	public static byte[][] encrypt(String data, char[] password) {
+		return encrypt(new SecureRandom().generateSeed(8), data, password);
 	}
-	
+
 	/**
 	 * Encrypts the data using the key made from the salt and password.
+	 * 
 	 * @param salt
 	 * @param data
 	 * @param password
-	 * @return A two-dimensional byte array where [0] is the salt bytes, [1] is the IV bytes and [2] is the encrypted data bytes.
+	 * @return A two-dimensional byte array where [0] is the salt bytes, [1] is
+	 *         the IV bytes and [2] is the encrypted data bytes.
 	 */
-	private static byte[][] encrypt(byte[] salt, String data, String password) {
+	private static byte[][] encrypt(byte[] salt, String data, char[] password) {
 		try {
-			SecretKey secret = composeKey(salt, password.toCharArray());
+			SecretKey secret = composeKey(salt, password);
 			Cipher cipher = Cipher.getInstance(CIPHER_TYPE);
 			cipher.init(Cipher.ENCRYPT_MODE, secret);
 			AlgorithmParameters params = cipher.getParameters();
 			byte[] iv = params.getParameterSpec(GCMParameterSpec.class).getIV();
 			byte[] cipherText = cipher.doFinal(data.getBytes());
-			
-			return new byte[][] {salt, iv, cipherText};
+
+			return new byte[][] { salt, iv, cipherText };
 		} catch (InvalidKeyException | NoSuchAlgorithmException | NoSuchPaddingException | IllegalBlockSizeException
 				| BadPaddingException | InvalidKeySpecException | InvalidParameterSpecException e) {
 			e.printStackTrace();
@@ -113,15 +127,21 @@ public class Encryption {
 		SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
 		return secret;
 	}
-	
+
 	/**
 	 * Testing method for encryption functionality.
+	 * 
 	 * @param args
 	 */
 	public static void main(String[] args) {
-		String encrypted = encrypt("asd", "password");
+		byte[][] encrypted = encrypt("asd", "password".toCharArray());
 		System.out.println(encrypted);
-		String decrypted = decrypt(encrypted, "password");
+		String decrypted = "";
+		try {
+			decrypted = decrypt(encrypted, "password".toCharArray());
+		} catch (InvalidPasswordException e) {
+			System.out.println("Wrong password");
+		}
 		System.out.println(decrypted);
 	}
 
@@ -130,6 +150,7 @@ public class Encryption {
 	final protected static char[] hexArray = "0123456789ABCDEF".toCharArray();
 
 	public static String bytesToHex(byte[] bytes) {
+		// Array to hold the chars, two chars for each byte
 		char[] hexChars = new char[bytes.length * 2];
 		for (int j = 0; j < bytes.length; j++) {
 			int v = bytes[j] & 0xFF;

src/eu/tankernn/accounts/frame/GUIUtils.java → src/eu/tankernn/accounts/util/GUIUtils.java

@@ -1,4 +1,4 @@
-package eu.tankernn.accounts.frame;
+package eu.tankernn.accounts.util;
 
 import java.util.List;
 

src/eu/tankernn/accounts/util/InvalidPasswordException.java

@@ -0,0 +1,10 @@
+package eu.tankernn.accounts.util;
+
+public class InvalidPasswordException extends Exception {
+
+	/**
+	 * 
+	 */
+	private static final long serialVersionUID = 1L;
+
+}