أريد مساعدة خطا في كد تشفير الrsa ولا ادري ماهوا

هذا كود اخذتوا من النت عن تشفير rsa

حاولت اشغلوا عندي بس فيه خطا

اتمنى احد يحاول يحل لي المشكلة ضروري

package gui;

import guiLogics.ClipboardCopyPaste;
import guiLogics.LoadSaveExec;

import java.awt.Color;
import java.awt.Container;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.math.BigInteger;

import javax.swing.ButtonGroup;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.KeyStroke;
import javax.swing.SwingConstants;
import javax.swing.SwingUtilities;
import javax.swing.WindowConstants;
import javax.swing.border.LineBorder;
import javax.swing.border.TitledBorder;

import keypair.GenerateKeys;
import keypair.GenerateUserKeys;
import keypair.OpenSave;
import keypair.RsaPrivateKey;
import keypair.RsaPublicKey;
import paddingSchemes.BlocksOf3Padding;
import paddingSchemes.PaddingType1;
import paddingSchemes.PaddingType2;

/**
 * Graphical User Interface for
 * the RSA Education Cryptosystem.
 *
 * @author Petri Tuononen
 * @since 7.2.2009
 */
public class Gui extends JFrame {

        private static final long serialVersionUID = -2015036022929739032L;

        //Constructor
        public Gui() {
                initComponents();
        }

        //Variables declaration
        private JMenuBar menuBar;

        private JMenu menu;
        private JMenu menu2;

        private JMenuItem menuItem1;
        private JMenuItem menuItem2;
        private JMenuItem menuItem3;

        private JRadioButton radioButton1;
        private JRadioButton radioButton2;
        private JRadioButton radioButton3;
        private JRadioButton radioButton4;
        private JRadioButton radioButton5;

        private JButton button1;
        private JButton button2;
        private JButton button3;
        private JButton button4;
        private JButton button5;
        private JButton button6;
        private JButton button7;
        private JButton button8;
        private JButton button9;
        private JButton button10;
        private JButton button11;
        private JButton button12;
        private JButton button13;

        private JPanel panel3;
        private JPanel panel6;
        private JPanel panel7;

        private JLabel label1;
        private JLabel label2;
        private JLabel label3;
        private JLabel label4;
        private JLabel label5;
        private JLabel label6;
        private JLabel label7;
        private JLabel label8;

        private JTextField textField1;
        private JTextField textField2;
        private JTextField textField3;
        private JTextField textField4;
        private JTextField textField5;
        private JTextField textField6;

        private JTextArea textArea1;
        private JTextArea textArea2;

        private JScrollPane scrollPane1;
        private JScrollPane scrollPane2;

        private JComboBox comboBox1;

        private ButtonGroup buttonGroup1;
        private ButtonGroup buttonGroup2;

        private RsaPublicKey publicKey;
        private RsaPrivateKey privateKey;
        private OpenSave openSave;
        private PaddingType1 padding1;
        private PaddingType2 padding2;
        private BlocksOf3Padding padding3;
        private ClipboardCopyPaste clipboard;
        private final String[] textSize = {"Font size 12 pt", "Font size 14 pt",
                        "Font size 16 pt", "Font size 18 pt", "Font size 20 pt"};
        private GradientPanel panel1;
        private GradientPanel panel2;
        private GradientPanel panel4;
        private GradientPanel panel5;

        private Color panelColor;
        //End of variables declaration

        private void initComponents() {
                //Component initialization
                menuBar = new JMenuBar();

                menu = new JMenu();
                menu2 = new JMenu();

                menuItem1 = new JMenuItem();
                menuItem2 = new JMenuItem();
                menuItem3 = new JMenuItem();

                radioButton1 = new JRadioButton();
                radioButton2 = new JRadioButton();
                radioButton3 = new JRadioButton();
                radioButton4 = new JRadioButton();
                radioButton5 = new JRadioButton();

                button1 = new JButton();
                button2 = new JButton();
                button3 = new JButton();
                button4 = new JButton();
                button5 = new JButton();
                button6 = new JButton();
                button7 = new JButton();
                button8 = new JButton();
                button9 = new JButton();
                button10 = new JButton();
                button11 = new JButton();
                button12 = new JButton();
                button13 = new JButton();

                panel3 = new JPanel();
                panel6 = new JPanel();
                panel7 = new JPanel();

                label1 = new JLabel();
                label2 = new JLabel();
                label3 = new JLabel();
                label4 = new JLabel();
                label5 = new JLabel();
                label6 = new JLabel();
                label7 = new JLabel();
                label8 = new JLabel();

                textField1 = new JTextField();
                textField2 = new JTextField();
                textField3 = new JTextField();
                textField4 = new JTextField();
                textField5 = new JTextField();
                textField6 = new JTextField();

                textArea1 = new JTextArea();
                textArea2 = new JTextArea();

                scrollPane1 = new JScrollPane();
                scrollPane2 = new JScrollPane();

                comboBox1 = new JComboBox(textSize);

                buttonGroup1 = new ButtonGroup();
                buttonGroup2 = new ButtonGroup();
               
                padding1 = new PaddingType1();
                padding2 = new PaddingType2();
                padding3 = new BlocksOf3Padding();
               
                clipboard = new ClipboardCopyPaste();

//              panelColor = new Color(117, 154, 178);
                panelColor = Color.LIGHT_GRAY;

                //======== container ========
                setTitle("RSA Education Cryptosystem");
                setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
                setVisible(true);
                try { //try to load icon image
                        ClassLoader cl = this.getClass().getClassLoader();
                        setIconImage(new ImageIcon(cl.getResource("images/icon.jpg")).getImage());
                }catch (Exception e) { //if not run from jar packet
                }
               
                Container contentPane = getContentPane();
                contentPane.setLayout(new GridBagLayout());
                ((GridBagLayout)contentPane.getLayout()).columnWidths = new int[] {10, 581, 10};
                ((GridBagLayout)contentPane.getLayout()).rowHeights = new int[] {3, 0, 10, 0, 10, 64, 10, 0, 10, 0, 10, 242, 5, 0, 0, 0};
                ((GridBagLayout)contentPane.getLayout()).rowWeights = new double[] {0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0, 1.0E-4};

                //======== menuBar ========
                {

                        //======== menu ========
                        {
                                menu.setText("File");

                                //---- menuItem3 ----
                                menuItem3.setText("Quit");
                                menuItem3.addActionListener(new ActionListener() {
                                        @Override
                                        public void actionPerformed(ActionEvent e) {
                                                quitMenuItemActionPerformed(e);
                                        }
                                });
                                menu.add(menuItem3);

                                menuBar.add(menu);

                                //======== menu2 ========
                                {
                                        menu2.setText("Help");

                                        //---- menuItem1 ----
                                        menuItem1.setText("Show help");
                                        menuItem1.addActionListener(new ActionListener() {
                                                @Override
                                                public void actionPerformed(ActionEvent e) {
                                                        showHelpMenuItemActionPerformed(e);
                                                }
                                        });
                                        //shortcut for help F11
                                        menuItem1.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_F11, 0));
                                        menu2.add(menuItem1);

                                        //---- menuItem2 ----
                                        menuItem2.setText("About");
                                        menuItem2.addActionListener(new ActionListener() {
                                                @Override
                                                public void actionPerformed(ActionEvent e) {
                                                        aboutMenuItemActionPerformed(e);
                                                }
                                        });
                                        menu2.add(menuItem2);
                                }
                                menuBar.add(menu2);
                        }
                }
                setJMenuBar(menuBar);

                //======== panel1 ========
                {
                        panel1 = new GradientPanel(panelColor, new GridBagLayout());
                        ((GridBagLayout)panel1.getLayout()).columnWidths = new int[] {25, 162, 32, 105, 110, 105, 105, 20, 0};
                        ((GridBagLayout)panel1.getLayout()).rowHeights = new int[] {12, 0, 0, 0, 0, 0, 5, 0};
                        ((GridBagLayout)panel1.getLayout()).columnWeights = new double[] {0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0E-4};
                        ((GridBagLayout)panel1.getLayout()).rowWeights = new double[] {0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0E-4};

                        panel1.setBorder(new TitledBorder(new LineBorder(Color.gray, 1, true), "Key creation"));

                        //---- label1 ----
                        label1.setText("p");
                        label1.setHorizontalAlignment(SwingConstants.CENTER);
                        panel1.add(label1, new GridBagConstraints(0, 1, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.VERTICAL,
                                        new Insets(0, 0, 5, 5), 0, 0));
                        panel1.add(textField1, new GridBagConstraints(1, 1, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- label4 ----
                        label4.setText("n");
                        label4.setHorizontalAlignment(SwingConstants.CENTER);
                        panel1.add(label4, new GridBagConstraints(2, 1, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- textField4 ----
                        textField4.setEditable(false);
                        panel1.add(textField4, new GridBagConstraints(3, 1, 4, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- label2 ----
                        label2.setText("q");
                        label2.setHorizontalAlignment(SwingConstants.CENTER);
                        panel1.add(label2, new GridBagConstraints(0, 2, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.VERTICAL,
                                        new Insets(0, 0, 5, 5), 0, 0));
                        panel1.add(textField2, new GridBagConstraints(1, 2, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- label5 ----
                        label5.setText("d");
                        label5.setHorizontalAlignment(SwingConstants.CENTER);
                        panel1.add(label5, new GridBagConstraints(2, 2, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- textField5 ----
                        textField5.setEditable(false);
                        panel1.add(textField5, new GridBagConstraints(3, 2, 4, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- label3 ----
                        label3.setText("e");
                        label3.setHorizontalAlignment(SwingConstants.CENTER);
                        panel1.add(label3, new GridBagConstraints(0, 3, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.VERTICAL,
                                        new Insets(0, 0, 5, 5), 0, 0));
                        panel1.add(textField3, new GridBagConstraints(1, 3, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- label6 ----
                        label6.setText("Save");
                        panel1.add(label6, new GridBagConstraints(5, 3, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.VERTICAL,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- label7 ----
                        label7.setText("Load");
                        panel1.add(label7, new GridBagConstraints(6, 3, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.VERTICAL,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- button11 ----
                        button11.setText("Clear keys");
                        button11.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        clearKeysButtonActionPerformed(e);
                                }
                        });
                        panel1.add(button11, new GridBagConstraints(4, 5, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- label8 ----
                        label8.setText("Prime bitsize");
                        label8.setVisible(false);
                        panel1.add(label8, new GridBagConstraints(3, 4, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.VERTICAL,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- button2 ----
                        button2.setText("Public key");
                        button2.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        savePublicKeyButtonActionPerformed(e);
                                }
                        });
                        panel1.add(button2, new GridBagConstraints(5, 4, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- button9 ----
                        button9.setText("Public key");
                        button9.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        loadPublicKeyButtonActionPerformed(e);
                                }
                        });
                        panel1.add(button9, new GridBagConstraints(6, 4, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- button1 ----
                        button1.setText("Create keys");
                        button1.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        createKeysButtonActionPerformed(e);
                                }
                        });
                        panel1.add(button1, new GridBagConstraints(1, 5, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));
                        panel1.add(textField6, new GridBagConstraints(3, 5, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        textField6.setVisible(false);

                        //---- button7 ----
                        button7.setText("Private key");
                        button7.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        savePrivateKeyButtonActionPerformed(e);
                                }
                        });
                        panel1.add(button7, new GridBagConstraints(5, 5, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));

                        //---- button10 ----
                        button10.setText("Private key");
                        button10.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        loadPrivateKeyButtonActionPerformed(e);
                                }
                        });
                        panel1.add(button10, new GridBagConstraints(6, 5, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));
                }
                contentPane.add(panel1, new GridBagConstraints(1, 3, 1, 1, 0.0, 0.0,
                                GridBagConstraints.CENTER, GridBagConstraints.VERTICAL,
                                new Insets(0, 0, 0, 0), 0, 0));

                //======== panel2 ========
                {
                        panel2 = new GradientPanel(panelColor, new GridBagLayout());
                        ((GridBagLayout)panel2.getLayout()).columnWidths = new int[] {10, 435, 5, 0};
                        ((GridBagLayout)panel2.getLayout()).rowHeights = new int[] {71, 5, 0};
                        ((GridBagLayout)panel2.getLayout()).columnWeights = new double[] {0.0, 1.0, 0.0, 1.0E-4};
                        ((GridBagLayout)panel2.getLayout()).rowWeights = new double[] {0.0, 0.0, 1.0E-4};

                        panel2.setBorder(new TitledBorder(new LineBorder(Color.gray, 1, true), "Message to encrypt/decrypt"));

                        //======== scrollPane2 ========
                        {

                                //---- textArea2 ----
                                textArea2.setLineWrap(true);
                                textArea2.setWrapStyleWord(true);
                                clipboard.createPopupMenu(textArea2);
                                scrollPane2.setViewportView(textArea2);
                        }
                        panel2.add(scrollPane2, new GridBagConstraints(1, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));
                }
                contentPane.add(panel2, new GridBagConstraints(1, 5, 1, 1, 0.0, 0.0,
                                GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                new Insets(0, 0, 0, 0), 0, 0));

                //======== panel3 ========
                {
                        panel3.setLayout(new GridBagLayout());
                        ((GridBagLayout)panel3.getLayout()).columnWidths = new int[] {155, 105, 20, 105, 150, 0};
                        ((GridBagLayout)panel3.getLayout()).rowHeights = new int[] {28, 0};
                        ((GridBagLayout)panel3.getLayout()).columnWeights = new double[] {1.0, 0.0, 0.0, 0.0, 1.0, 1.0E-4};
                        ((GridBagLayout)panel3.getLayout()).rowWeights = new double[] {0.0, 1.0E-4};

                        //---- button3 ----
                        button3.setText("Encrypt");
                        button3.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        encryptButtonActionPerformed(e);
                                }
                        });
                        panel3.add(button3, new GridBagConstraints(1, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 0, 5), 0, 0));

                        //---- button4 ----
                        button4.setText("Decrypt");
                        button4.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        decryptButtonActionPerformed(e);
                                }
                        });
                        panel3.add(button4, new GridBagConstraints(3, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 0, 5), 0, 0));
                }
                contentPane.add(panel3, new GridBagConstraints(1, 9, 1, 1, 0.0, 0.0,
                                GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                new Insets(0, 0, 0, 0), 0, 0));

                //======== panel4 ========
                {
                        panel4 = new GradientPanel(panelColor, new GridBagLayout());
                        panel4.setBorder(new TitledBorder(new LineBorder(Color.gray, 1, true), "Padding scheme"));
                        ((GridBagLayout)panel4.getLayout()).columnWidths = new int[] {80, 81, 80, 0};
                        ((GridBagLayout)panel4.getLayout()).rowHeights = new int[] {0, 0};
                        ((GridBagLayout)panel4.getLayout()).columnWeights = new double[] {0.0, 0.0, 0.0, 1.0E-4};
                        ((GridBagLayout)panel4.getLayout()).rowWeights = new double[] {0.0, 1.0E-4};

                        //---- radioButton3 ----
                        radioButton3.setText("One letter");
                        radioButton3.setOpaque(false);
                        radioButton3.setSelected(true);
                        panel4.add(radioButton3, new GridBagConstraints(0, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 0, 5), 0, 0));
                       
                        //---- radioButton4 ----
                        radioButton4.setText("Two letters");
                        radioButton4.setOpaque(false);
                        panel4.add(radioButton4, new GridBagConstraints(1, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 0, 5), 0, 0));
                       
                        //---- radioButton5 ----
                        radioButton5.setText("Three letters");
                        radioButton5.setOpaque(false);
                        panel4.add(radioButton5, new GridBagConstraints(2, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 0, 0), 0, 0));
                }
                contentPane.add(panel4, new GridBagConstraints(1, 7, 1, 1, 0.0, 0.0,
                                GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                new Insets(0, 0, 0, 0), 0, 0));

                //======== panel5 ========
                {
                        panel5 = new GradientPanel(panelColor, new GridBagLayout());
                        ((GridBagLayout)panel5.getLayout()).columnWidths = new int[] {10, 0, 5, 0};
                        ((GridBagLayout)panel5.getLayout()).rowHeights = new int[] {210, 0, 0};
                        ((GridBagLayout)panel5.getLayout()).columnWeights = new double[] {0.0, 1.0, 0.0, 1.0E-4};
                        ((GridBagLayout)panel5.getLayout()).rowWeights = new double[] {0.0, 0.0, 1.0E-4};

                        panel5.setBorder(new TitledBorder(new LineBorder(Color.gray, 1, true), "RSA execution"));

                        //======== scrollPane1 ========
                        {
                                scrollPane1.setViewportView(textArea1);
                        }

                        clipboard.createPopupMenu(textArea1);

                        panel5.add(scrollPane1, new GridBagConstraints(1, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 5, 5), 0, 0));
                }
                contentPane.add(panel5, new GridBagConstraints(1, 11, 1, 1, 0.0, 0.0,
                                GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                new Insets(0, 0, 0, 0), 0, 0));


                //======== panel6 ========
                {
                        panel6.setLayout(new GridBagLayout());
                        ((GridBagLayout)panel6.getLayout()).columnWidths = new int[] {0, 0, 15, 65, 55, 15, 119, 90, 0};
                        ((GridBagLayout)panel6.getLayout()).rowHeights = new int[] {0, 0};
                        ((GridBagLayout)panel6.getLayout()).columnWeights = new double[] {0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0E-4};
                        ((GridBagLayout)panel6.getLayout()).rowWeights = new double[] {0.0, 1.0E-4};

                        //---- button5 ----
                        button5.setText("Save to file");
                        button5.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        saveExecutionButtonActionPerformed(e);
                                }
                        });
                        panel6.add(button5, new GridBagConstraints(0, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 0, 5), 0, 0));

                        //---- button6 ----
                        button6.setText("Load from file");
                        button6.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        loadExecutionButtonActionPerformed(e);
                                }
                        });
                        panel6.add(button6, new GridBagConstraints(1, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 0, 5), 0, 0));

                        //---- button12 ----
                        button12.setText("Clear");
                        button12.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        ClearExecButtonActionPerformed(e);
                                }
                        });
                        panel6.add(button12, new GridBagConstraints(3, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 0, 5), 0, 0));

                        //---- button13 ----
                        button13.setText("Copy to clipboard");
                        button13.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        copyToClipboardButtonActionPerformed(e);
                                }
                        });
                        panel6.add(button13, new GridBagConstraints(4, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 0, 5), 0, 0));

                        //---- comboBox1 ----
                        comboBox1.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        fontSizeComboBoxActionPerformed(e);
                                }
                        });
                        panel6.add(comboBox1, new GridBagConstraints(6, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 0, 5), 0, 0));

                        //---- button8 ----
                        button8.setText("Full screen");
                        button8.setPreferredSize(new Dimension(100, 23));
                        button8.setMaximumSize(new Dimension(100, 23));
                        button8.setMinimumSize(new Dimension(100, 23));
                        button8.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        fullScreenButtonActionPerformed(e);
                                }
                        });
                        panel6.add(button8, new GridBagConstraints(7, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.EAST, GridBagConstraints.VERTICAL,
                                        new Insets(0, 0, 0, 0), 0, 0));
                }
                contentPane.add(panel6, new GridBagConstraints(1, 13, 1, 1, 0.0, 0.0,
                                GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                new Insets(0, 0, 0, 0), 0, 0));

                //======== panel7 ========
                {
                        panel7.setLayout(new GridBagLayout());
                        ((GridBagLayout)panel7.getLayout()).columnWidths = new int[] {0, 10, 0, 10, 0};
                        ((GridBagLayout)panel7.getLayout()).rowHeights = new int[] {0, 0};
                        ((GridBagLayout)panel7.getLayout()).columnWeights = new double[] {0.0, 0.0, 0.0, 0.0, 1.0E-4};
                        ((GridBagLayout)panel7.getLayout()).rowWeights = new double[] {0.0, 1.0E-4};

                        //---- radioButton1 ----
                        radioButton1.setText("Teach mode");
                        radioButton1.setSelected(true);
                        radioButton1.setActionCommand("Teach mode");
                        radioButton1.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        teachModeRadioButtonActionPerformed(e);
                                }
                        });
                        panel7.add(radioButton1, new GridBagConstraints(0, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 0, 5), 0, 0));

                        //---- radioButton2 ----
                        radioButton2.setText("Secure mode");
                        radioButton2.setActionCommand("Secure mode");
                        radioButton2.addActionListener(new ActionListener() {
                                @Override
                                public void actionPerformed(ActionEvent e) {
                                        secureModeRadioButtonActionPerformed(e);
                                }
                        });
                        panel7.add(radioButton2, new GridBagConstraints(2, 0, 1, 1, 0.0, 0.0,
                                        GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                        new Insets(0, 0, 0, 5), 0, 0));
                }
                contentPane.add(panel7, new GridBagConstraints(1, 1, 1, 1, 0.0, 0.0,
                                GridBagConstraints.CENTER, GridBagConstraints.BOTH,
                                new Insets(0, 0, 0, 0), 0, 0));

                setSize(750, 775);
                setLocationRelativeTo(null);
                toFront();
                setVisible(true);

                //---- buttonGroup1 ----
                buttonGroup1.add(radioButton1);
                buttonGroup1.add(radioButton2);
               
                //---- buttonGroup2 ----
                buttonGroup2.add(radioButton3);
                buttonGroup2.add(radioButton4);
                buttonGroup2.add(radioButton5);
                //End of component initialization
        }

        //Event handlers

        /**
         * Teach mode radiobutton pressed.
         */
        private void teachModeRadioButtonActionPerformed(ActionEvent e) {
                teachModeButtonPressed();
        }

        /**
         * Secure mode radiobutton pressed.
         * @param e
         */
        private void secureModeRadioButtonActionPerformed(ActionEvent e) {
                secureModeButtonPressed();
        }

        /**
         * 'Quit' File menu item pressed.
         * @param e
         */
        private void quitMenuItemActionPerformed(ActionEvent e) {
                dispose();
        }

        /**
         * 'Show help' menu item pressed.
         * @param e
         */
        private void showHelpMenuItemActionPerformed(ActionEvent e) {
                new Help().toFront();
        }

        /**
         * 'About' menu item pressed.
         * @param e
         */
        private void aboutMenuItemActionPerformed(ActionEvent e) {
                showAbout();
        }

        /**
         * 'Save public key' button pressed.
         * @param e
         */
        private void savePublicKeyButtonActionPerformed(ActionEvent e) {
                savePublicKey();
        }

        /**
         * 'Load public key' button pressed.
         * @param e
         */
        private void loadPublicKeyButtonActionPerformed(ActionEvent e) {
                loadPublicKey();
        }

        /**
         * 'Save private key' button pressed.
         * @param e
         */
        private void savePrivateKeyButtonActionPerformed(ActionEvent e) {
                savePrivateKey();
        }

        /**
         * 'Load private key' button pressed.
         * @param e
         */
        private void loadPrivateKeyButtonActionPerformed(ActionEvent e) {
                loadPrivateKey();
        }

        /**
         * 'Encrypt' button pressed.
         * @param e
         */
        private void encryptButtonActionPerformed(ActionEvent e) {
                encrypt();
        }

        /**
         * 'Decrypt' button pressed.
         * @param e
         */
        private void decryptButtonActionPerformed(ActionEvent e) {
                decrypt();
        }

        /**
         * 'Save to file' button pressed.
         * @param e
         */
        private void saveExecutionButtonActionPerformed(ActionEvent e) {
                saveExecution();
        }

        /**
         * 'Load from file' button pressed.
         * @param e
         */
        private void loadExecutionButtonActionPerformed(ActionEvent e) {
                loadExecution();
        }

        /**
         * Font selected from font size combo box.
         * @param e
         */
        private void fontSizeComboBoxActionPerformed(ActionEvent e) {
                fontSizeChange();
        }

        /**
         * 'Full screen' button pressed.
         * @param e
         */
        private void fullScreenButtonActionPerformed(ActionEvent e) {
                showExecFullScreen();
        }

        /**
         * 'Create keys' button pressed.
         * @param e
         */
        private void createKeysButtonActionPerformed(ActionEvent e) {
                createKeys();
        }

        /**
         * 'Clear keys' button pressed.
         * @param e
         */
        private void clearKeysButtonActionPerformed(ActionEvent e) {
                //Clear p, q, e, n, d textfields
                clearKeyTextFields();
                //delete keys
                publicKey = null;
                privateKey = null;
        }

        /**
         * 'Clear' button pressed.
         * @param e
         */
        private void ClearExecButtonActionPerformed(ActionEvent e) {
                //Clear execution textarea
                textArea1.setText("");
        }

        /**
         * 'Copy to clipboard' button pressed.
         * @param e
         */
        private void copyToClipboardButtonActionPerformed(ActionEvent e) {
                new ClipboardCopyPaste().copy(textArea1.getText());
        }
        //End of event handlers.

        //Methods used in event handlers.

        /**
         * Clears textfields containing key info.
         */
        private void clearKeyTextFields() {
                //Clear p, q, e, n, d textfields
                textField1.setText("");
                textField2.setText("");
                textField3.setText("");
                textField4.setText("");
                textField5.setText("");
        }

        /**
         * Generates keys.
         */
        private void createKeys() {
                //teach mode
                if (buttonGroup1.getSelection().getActionCommand().equals("Teach mode")) {
                        try {
                                //get user input
                                BigInteger p = new BigInteger(textField1.getText());
                                BigInteger q = new BigInteger(textField2.getText());
                                BigInteger e = new BigInteger(textField3.getText());

                                GenerateUserKeys genKeys = new GenerateUserKeys();

                                //test that p, q and e are suitable
                                if (genKeys.testInputEligibility(p, q, e)) { //input ok
                                        //generate keys
                                        setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
                                        genKeys.createKeys(p, q, e);
                                        setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
                                        //store keys
                                        publicKey = genKeys.getPublicKey();
                                        privateKey = genKeys.getPrivateKey();

                                        //write to textfields
                                        textField4.setText(publicKey.getN().toString());
                                        textField5.setText(privateKey.getPrivateExponent().toString());
                                }
                                else { //bad input
                                        genKeys.showInputError(this, p, q, e);
                                }
                        }catch(Exception e) {
                                JOptionPane.showMessageDialog(this, "Key creation error.", "Error", JOptionPane.ERROR_MESSAGE);
                        }
                }
                //secure mode
                else if (buttonGroup1.getSelection().getActionCommand().equals("Secure mode")) {
                        //bitsize field is empty
                        if (textField6.getText().equals("")) {
                                JOptionPane.showMessageDialog(this, "Bitsize field is empty.", "Bitsize error", JOptionPane.ERROR_MESSAGE);
                        }else {
                                int value = 0;
                                if (Integer.parseInt(textField6.getText()) > 2048) {
                                        //value=0 OK, value=2 CANCEL
                                        value = JOptionPane.showConfirmDialog(this, "Are you sure you want to create primes larger than 2048 bits? It will take some time.", "Large bitsize warning", JOptionPane.OK_CANCEL_OPTION, JOptionPane.INFORMATION_MESSAGE);
                                }
                                if (value==0) {
                                        if (Integer.parseInt(textField6.getText()) <= 5) { //bit size under 5 bits.
                                                JOptionPane.showMessageDialog(this, "Prime bitsize must be larger than 5.", "Bitsize error", JOptionPane.ERROR_MESSAGE);
                                        }else { //bit size is ok.
                                                setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
                                                GenerateKeys genKeys = new GenerateKeys(Integer.parseInt(textField6.getText()));
                                                publicKey = genKeys.getPublicKey();
                                                privateKey = genKeys.getPrivateKey();
                                                setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
                                        }
                                }
                        }
                }
        }

        /**
         * Saves a public key to a file.
         */
        private void savePublicKey() {
                if (publicKey!=null) {
                        openSave = new OpenSave(this);
                        openSave.savePublicKey(publicKey);
                }else {
                        JOptionPane.showMessageDialog(this, "Public key is not created.", "Public key save error", JOptionPane.ERROR_MESSAGE);
                }
        }

        /**
         * Loads a public key from a file.
         */
        private void loadPublicKey() {
                openSave = new OpenSave(this);
                RsaPublicKey pubKey = null;
                try {
                        pubKey = openSave.loadPublicKey();
                }catch(Exception e) {
                        JOptionPane.showMessageDialog(this, "Public key couldn't be loaded.", "Public key load error", JOptionPane.ERROR_MESSAGE);
                }
                if (pubKey != null) {
                        clearKeyTextFields();
                        publicKey = pubKey;
                        privateKey = null;
                        if (buttonGroup1.getSelection().getActionCommand().equals("Teach mode")) {
                                //public key fields
                                textField3.setText(publicKey.getE().toString());
                                textField4.setText(publicKey.getN().toString());
                               
                                //private key fields
                                textField1.setText("");
                                textField2.setText("");
                                textField5.setText("");
                        }
                }
        }

        /**
         * Saves a private key to a file.
         */
        private void savePrivateKey() {
                if (privateKey!=null) {
                        openSave = new OpenSave(this);
                        openSave.savePrivateKey(privateKey);
                }else {
                        JOptionPane.showMessageDialog(this, "Private key is not created.", "Private key save error", JOptionPane.ERROR_MESSAGE);
                }
        }

        /**
         * Loads a private key from a file.
         */
        private void loadPrivateKey() {
                openSave = new OpenSave(this);
                RsaPrivateKey privKey = null;
                try {
                        //create private & public keys and write values to textfields
                        privKey = openSave.loadPrivateKey();
                }catch(Exception e) {
                        JOptionPane.showMessageDialog(this, "Private key couldn't be loaded.", "Private key load error", JOptionPane.ERROR_MESSAGE);
                }
                if (privKey != null) {
                        privateKey = privKey;
                        publicKey = new RsaPublicKey(privateKey.getN(), privateKey.getE());
                        if (buttonGroup1.getSelection().getActionCommand().equals("Teach mode")) {
                                textField1.setText(privateKey.getPrimeP().toString());
                                textField2.setText(privateKey.getPrimeQ().toString());
                                textField3.setText(privateKey.getE().toString());
                                textField4.setText(privateKey.getN().toString());
                                textField5.setText(privateKey.getPrivateExponent().toString());
                        }
                }
        }

        /**
         * Saves execution textarea contents to a file.
         */
        private void saveExecution() {
                new LoadSaveExec(this, textArea1).saveExecToFile();
        }

        /**
         * Loads content to the execution textarea from a file.
         */
        private void loadExecution() {
                new LoadSaveExec(this, textArea1).loadExecFromFile();
        }

        /**
         * Show execution content in a full screen frame.
         */
        private void showExecFullScreen() {
                new FullScreen(textArea1);
        }

        /**
         * Encrypts the text written in 'Message to encrypt/decrypt' textarea.
         */
        private void encrypt() {
                if (publicKey == null) {
                        JOptionPane.showMessageDialog(this, "Public key not created", "Public key error", JOptionPane.ERROR_MESSAGE);
                }
                //teach mode
                if (buttonGroup1.getSelection().getActionCommand().equals("Teach mode")) {
                        // if padding type1 checkbox is selected
                        if(radioButton3.isSelected()){
                                // get plaintext from textarea
                                String plaintext = textArea2.getText().toUpperCase();
                                // if something is written into the message textarea and public key is generated.
                                if (!plaintext.isEmpty() && publicKey != null) {
                                        // check that n > 25. This is requirement for padding type 1
                                        if (publicKey.getN().compareTo(new BigInteger("25"))>0){
                                                // check that input contains only allowed letters and catch all errors
                                                try{
                                                        textArea1.setText(padding1.getEnCrypted(plaintext, publicKey.getPublicExponent(), publicKey.getModulus()));
                                                        textArea1.setCaretPosition(0);
                                                }catch (Exception e){
                                                        JOptionPane.showMessageDialog(this, "Only letters A - Z are allowed.", "Input error", JOptionPane.ERROR_MESSAGE);
                                                }
                                        }else {
                                                JOptionPane.showMessageDialog(this, "One letter padding scheme requires n > 25", "Input error", JOptionPane.ERROR_MESSAGE);
                                        }
                                }
                        }
                        //if padding type2 checkbox is selected
                        else if(radioButton4.isSelected()){
                                // get plaintext from textarea
                                String plaintext = textArea2.getText().toUpperCase();
                                // if something is written into the message textarea and public key is generated.
                                if (!plaintext.isEmpty() && publicKey != null) {
                                        // check that n > 2525. This is requirement for padding type 2
                                        if (publicKey.getN().compareTo(new BigInteger("2525"))>0){
                                                // check that input contains only allowed letters and catch all errors
                                                try{
                                                        textArea1.setText(padding2.getEnCrypted(plaintext, publicKey.getPublicExponent(), publicKey.getModulus()));
                                                        textArea1.setCaretPosition(0);
                                                }catch(Exception e){
                                                        JOptionPane.showMessageDialog(this, "Only letters A - Z are allowed.", "Input error", JOptionPane.ERROR_MESSAGE);
                                                }
                                        }else {
                                                JOptionPane.showMessageDialog(this, "Two letters padding scheme requires n > 2525", "Input error", JOptionPane.ERROR_MESSAGE);
                                        }
                                }
                        }
                        //if blocks of three letters padding scheme checkbox is selected
                        else if (radioButton5.isSelected()) {
                                //get plaintext from textarea
                                String plaintext = textArea2.getText().toUpperCase();
                                //if something is written into the message textarea and public key is generated.
                                if (!plaintext.isEmpty() && publicKey != null) {
                                        // check that n > 17575. This is requirement for padding type 3
                                        if (publicKey.getN().compareTo(new BigInteger("17575"))>0){
                                                // check that input contains only allowed letters and catch all errors
                                                try{
                                                        textArea1.setText(padding3.getEncodeAndEncryptBlocksOfThree(plaintext, publicKey.getPublicExponent(), publicKey.getModulus()));
                                                        textArea1.setCaretPosition(0);
                                                }catch (Exception e){
                                                        JOptionPane.showMessageDialog(this, "Only letters A - Z are allowed.", "Input error", JOptionPane.ERROR_MESSAGE);
                                                }
                                        }else {
                                                JOptionPane.showMessageDialog(this, "Three letters padding scheme letters requires n > 17575", "Input error", JOptionPane.ERROR_MESSAGE);
                                        }
                                }
                        }
                }
                //secure mode
                else if (buttonGroup1.getSelection().getActionCommand().equals("Secure mode")) {
                        // if padding type1 checkbox is selected
                        if(radioButton3.isSelected()){
                                // get plaintext from textarea
                                String plaintext = textArea2.getText().toUpperCase();
                                // if something is written into the message textarea and public key is generated.
                                if (!plaintext.isEmpty() && publicKey != null) {
                                        // check that n > 25. This is requirement for padding type 1
                                        if (publicKey.getN().compareTo(new BigInteger("25"))>0){
                                                // check that input contains only allowed letters and catch all errors
                                                try{
                                                        textArea1.setText(padding1.getEnCryptedSecure(plaintext, publicKey.getPublicExponent(), publicKey.getModulus()));
                                                        textArea1.setCaretPosition(0);
                                                }catch (Exception e){
                                                        JOptionPane.showMessageDialog(this, "Only letters A - Z are allowed.", "Input error", JOptionPane.ERROR_MESSAGE);
                                                }
                                        }else {
                                                JOptionPane.showMessageDialog(this, "One letter padding scheme requires n > 25", "Input error", JOptionPane.ERROR_MESSAGE);
                                        }
                                }
                        }
                        //if padding type2 checkbox is selected
                        else if(radioButton4.isSelected()){
                                // get plaintext from textarea
                                String plaintext = textArea2.getText().toUpperCase();
                                // if something is written into the message textarea and public key is generated.
                                if (!plaintext.isEmpty() && publicKey != null) {
                                        // check that n > 2525. This is requirement for padding type 2
                                        if (publicKey.getN().compareTo(new BigInteger("2525"))>0){
                                                // check that input contains only allowed letters and catch all errors
                                                try{
                                                textArea1.setText(padding2.getEnCryptedSecure(plaintext, publicKey.getPublicExponent(), publicKey.getModulus()));
                                                textArea1.setCaretPosition(0);
                                                }catch (Exception e){
                                                        JOptionPane.showMessageDialog(this, "Only letters A - Z are allowed.", "Input error", JOptionPane.ERROR_MESSAGE);
                                                }
                                        }else {
                                                JOptionPane.showMessageDialog(this, "Two letters padding scheme requires n > 2525", "Input error", JOptionPane.ERROR_MESSAGE);
                                        }
                                }
                        }
                        //if blocks of three letters padding scheme checkbox is selected
                        else if (radioButton5.isSelected()) {
                                //get plaintext from textarea
                                String plaintext = textArea2.getText().toUpperCase();
                                //if something is written into the message textarea and public key is generated.
                                if (!plaintext.isEmpty() && publicKey != null) {
                                        // check that n > 17575. This is requirement for padding type 3
                                        if (publicKey.getN().compareTo(new BigInteger("17575"))>0){
                                                // check that input contains only allowed letters and catch all errors
                                                try{
                                                textArea1.setText(padding3.getEncodeAndEncryptSecure(plaintext, publicKey.getPublicExponent(), publicKey.getModulus()));
                                                textArea1.setCaretPosition(0);
                                                }catch (Exception e){
                                                        JOptionPane.showMessageDialog(this, "Only letters A - Z are allowed.", "Input error", JOptionPane.ERROR_MESSAGE);
                                                }
                                        }else {
                                                JOptionPane.showMessageDialog(this, "Three letters padding scheme letters requires n > 17575", "Input error", JOptionPane.ERROR_MESSAGE);
                                        }
                                }
                        }
                }
        }

        /**
         * Decrypts the text written in 'Message to encrypt/decrypt' textarea.
         */
        private void decrypt() {
                if (privateKey == null) {
                        JOptionPane.showMessageDialog(this, "Private key not created", "Private key error", JOptionPane.ERROR_MESSAGE);
                }
                //teach mode
                if (buttonGroup1.getSelection().getActionCommand().equals("Teach mode")) {
                        // if padding scheme1 checkbox is selected
                        if (radioButton3.isSelected()){
                                // get encrypted text from textarea
                                String encrypted = textArea2.getText();
                                //if something is written into the message textarea and private key is generated.
                                if (!encrypted.isEmpty() && privateKey != null) {
                                        // check that n > 25. This is requirement for padding type 1
                                        if (privateKey.getN().compareTo(new BigInteger("25"))>0){
                                                // catch exceptions (exception comes if textarea contains illeagal letters
                                                try{
                                                        textArea1.setText(padding1.getDeCrypted(encrypted, privateKey.getPrivateExponent(), privateKey.getModulus()));
                                                        textArea1.setCaretPosition(0);
                                                }catch(Exception e){
                                                        JOptionPane.showMessageDialog(this, "Not a genuine cryptotext.", "Input error", JOptionPane.ERROR_MESSAGE);
                                                }
                                        }else {
                                                JOptionPane.showMessageDialog(this, "One letter padding scheme requires n > 25", "Input error", JOptionPane.ERROR_MESSAGE);
                                        }
                                }
                        }
                        // if padding scheme2 checkbox is selected
                        else if (radioButton4.isSelected()){
                                // get encrypted text from textarea
                                String encrypted = textArea2.getText();
                                //if something is written into the message textarea and private key is generated.
                                if (!encrypted.isEmpty() && privateKey != null) {
                                        // check that n > 2525. This is requirement for padding type 2
                                        if (privateKey.getN().compareTo(new BigInteger("2525"))>0){
                                                // catch exceptions (exception comes if textarea contains illeagal letters
                                                try{
                                                        textArea1.setText(padding2.getDeCrypted(encrypted, privateKey.getPrivateExponent(), privateKey.getModulus()));
                                                        textArea1.setCaretPosition(0);
                                                }catch(Exception e){
                                                        JOptionPane.showMessageDialog(this, "Not a genuine cryptotext.", "Input error", JOptionPane.ERROR_MESSAGE);
                                                }
                                        }else {
                                                JOptionPane.showMessageDialog(this, "Two letters padding scheme requires n > 2525", "Input error", JOptionPane.ERROR_MESSAGE);
                                        }
                                }
                        }
                        //if blocks of three letters padding scheme checkbox is selected
                        else if (radioButton5.isSelected()) {
                                //get encrypted text from textarea
                                String encrypted = textArea2.getText();
                                //if something is written into the message textarea and private key is generated.
                                if (!encrypted.isEmpty() && privateKey != null) {
                                        // check that n > 17575. This is requirement for padding type 3
                                        if (privateKey.getN().compareTo(new BigInteger("17575"))>0){
                                                // catch exceptions (exception comes if textarea contains illeagal letters
                                                try{
                                                        textArea1.setText(padding3.getDecryptAndDecodeBlocksOfThree(encrypted, privateKey.getPrivateExponent(), privateKey.getModulus()));
                                                        textArea1.setCaretPosition(0);
                                                }catch(Exception e){
                                                        JOptionPane.showMessageDialog(this, "Not a genuine cryptotext.", "Input error", JOptionPane.ERROR_MESSAGE);
                                                }
                                        }else {
                                                JOptionPane.showMessageDialog(this, "Three letters padding scheme requires n > 17575", "Input error", JOptionPane.ERROR_MESSAGE);
                                        }
                                }
                        }
                }

                //secure mode
                else if (buttonGroup1.getSelection().getActionCommand().equals("Secure mode")) {
                        // if padding scheme1 checkbox is selected
                        if (radioButton3.isSelected()){
                                // get encrypted text from textarea
                                String encrypted = textArea2.getText();
                                //if something is written into the message textarea and private key is generated.
                                if (!encrypted.isEmpty() && privateKey != null) {
                                        // check that n > 25. This is requirement for padding type 1
                                        if (privateKey.getN().compareTo(new BigInteger("25"))>0){
                                                // catch exceptions (exception comes if textarea contains illeagal letters
                                                try{
                                                        textArea1.setText(padding1.getDeCryptedSecure(encrypted, privateKey.getPrivateExponent(), privateKey.getModulus()));
                                                        textArea1.setCaretPosition(0);
                                                }catch(Exception e){
                                                        JOptionPane.showMessageDialog(this, "Not a genuine cryptotext.", "Input error", JOptionPane.ERROR_MESSAGE);
                                                }
                                        }else {
                                                JOptionPane.showMessageDialog(this, "One letter padding scheme requires n > 25", "Input error", JOptionPane.ERROR_MESSAGE);
                                        }
                                }
                        }
                        // if padding scheme2 checkbox is selected
                        else if (radioButton4.isSelected()){
                                // get encrypted text from textarea
                                String encrypted = textArea2.getText();
                                //if something is written into the message textarea and private key is generated.
                                if (!encrypted.isEmpty() && privateKey != null) {
                                        // check that n > 2525. This is requirement for padding type 2
                                        if (privateKey.getN().compareTo(new BigInteger("2525"))>0){
                                                // catch exceptions (exception comes if textarea contains illeagal letters
                                                try{
                                                        textArea1.setText(padding2.getDeCryptedSecure(encrypted, privateKey.getPrivateExponent(), privateKey.getModulus()));
                                                        textArea1.setCaretPosition(0);
                                                }catch(Exception e){
                                                        JOptionPane.showMessageDialog(this, "Not a genuine cryptotext.", "Input error", JOptionPane.ERROR_MESSAGE);
                                                }
                                        }else {
                                                JOptionPane.showMessageDialog(this, "Two letters padding scheme requires n > 2525", "Input error", JOptionPane.ERROR_MESSAGE);
                                        }
                                }
                        }
                        //if blocks of three letters padding scheme checkbox is selected
                        else if (radioButton5.isSelected()) {
                                //get encrypted text from textarea
                                String encrypted = textArea2.getText();
                                //if something is written into the message textarea and private key is generated.
                                if (!encrypted.isEmpty() && privateKey != null) {
                                        // check that n > 17575. This is requirement for padding type 3
                                        if (privateKey.getN().compareTo(new BigInteger("17575"))>0){
                                                // catch exceptions (exception comes if textarea contains illeagal letters
                                                try{
                                                        textArea1.setText(padding3.getDecryptAndDecodeSecure(encrypted, privateKey.getPrivateExponent(), privateKey.getModulus()));
                                                        textArea1.setCaretPosition(0);
                                                }catch(Exception e){
                                                        JOptionPane.showMessageDialog(this, "Not a genuine cryptotext.", "Input error", JOptionPane.ERROR_MESSAGE);
                                                }
                                        }else {
                                                JOptionPane.showMessageDialog(this, "Three letters padding scheme requires n > 17575", "Input error", JOptionPane.ERROR_MESSAGE);
                                        }
                                }
                        }
                }
        }


        /**
         * Changes execution textarea's font size.
         */
        private void fontSizeChange() {
                if (comboBox1.getSelectedItem() == "Font size 12 pt") {
                        textArea1.setFont(new Font("Arial Unicode MS", Font.PLAIN, 12));
                }
                else if (comboBox1.getSelectedItem() == "Font size 14 pt") {
                        textArea1.setFont(new Font("Arial Unicode MS", Font.PLAIN, 14));
                }
                else if (comboBox1.getSelectedItem() == "Font size 16 pt") {
                        textArea1.setFont(new Font("Arial Unicode MS", Font.PLAIN, 16));
                }
                else if (comboBox1.getSelectedItem() == "Font size 18 pt") {
                        textArea1.setFont(new Font("Arial Unicode MS", Font.PLAIN, 18));
                }
                else if (comboBox1.getSelectedItem() == "Font size 20 pt") {
                        textArea1.setFont(new Font("Arial Unicode MS", Font.PLAIN, 20));
                }
        }

        /**
         * Secure mode button action.
         * Bit size textfield is made visible and
         * some textfields used by teach mode
         * are made invisible.
         */
        private void secureModeButtonPressed() {
                textArea1.setText("");
                textField6.setVisible(true);
                label8.setVisible(true);
                textField1.setVisible(false);
                textField2.setVisible(false);
                textField3.setVisible(false);
                label1.setVisible(false);
                label2.setVisible(false);
                label3.setVisible(false);
                label4.setVisible(false);
                label5.setVisible(false);
                textField4.setVisible(false);
                textField5.setVisible(false);
        }

        /**
         * Teach mode button action.
         * Bit size textfield is made invisible
         * and key textfields visible.
         */
        private void teachModeButtonPressed() {
                textArea1.setText("");
                textField6.setVisible(false);
                label8.setVisible(false);
                textField1.setVisible(true);
                textField2.setVisible(true);
                textField3.setVisible(true);
                label1.setVisible(true);
                label2.setVisible(true);
                label3.setVisible(true);
                label4.setVisible(true);
                label5.setVisible(true);
                textField4.setVisible(true);
                textField5.setVisible(true);
        }
       
        /**
         * Shows about screen.
         */
        private void showAbout() {
                JOptionPane.showMessageDialog(this,
                                "Authors: Petri Tuononen, Jukka Tuominen, Jani Kirsi.\n" +
                                "Date: 27.02.2009\n" +
                                "Version: 1.0\n" +
                                "Info: This software is a part of OOP course work at Turku University of Applied Sciences.\n" +
                                "GPL lisence: This software can be used, modified and redistibuted freely.\n" +
                                "No warranties of any kind.\n" +
                                "Feedback: petri.tuononen@gmail.com", "About",
                                JOptionPane.PLAIN_MESSAGE);
        }

        //End of methods used in event handlers.

        /**
         * Executes GUI in a thread.
         */
        public static void main(String[] args) {
                SwingUtilities.invokeLater(new Runnable() {
                        @Override
                        public void run() {
                                JFrame.setDefaultLookAndFeelDecorated(false);
                                new Gui();
                        }
                });
        }

}