Java/Security/General

Message Digest Test

   <source lang="java">

import java.awt.Container; import java.awt.Font; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import javax.swing.ButtonGroup; import javax.swing.JCheckBox; import javax.swing.JFileChooser; import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTextArea; import javax.swing.JTextField; public class MessageDigestTest {

 public static void main(String[] args) {
   JFrame f = new MessageDigestFrame();
   f.show();
 }

} class MessageDigestFrame extends JFrame {

 public MessageDigestFrame() {
   setTitle("MessageDigestTest");
   setSize(400, 200);
   addWindowListener(new WindowAdapter() {
     public void windowClosing(WindowEvent e) {
       System.exit(0);
     }
   });
   JPanel panel = new JPanel();
   ButtonGroup group = new ButtonGroup();
   ActionListener listener = new ActionListener() {
     public void actionPerformed(ActionEvent event) {
       JCheckBox b = (JCheckBox) event.getSource();
       setAlgorithm(b.getText());
     }
   };
   addCheckBox(panel, "SHA-1", group, true, listener);
   addCheckBox(panel, "MD5", group, false, listener);
   Container contentPane = getContentPane();
   contentPane.add(panel, "North");
   contentPane.add(new JScrollPane(message), "Center");
   contentPane.add(digest, "South");
   digest.setFont(new Font("Monospaced", Font.PLAIN, 12));
   setAlgorithm("SHA-1");
   JMenuBar menuBar = new JMenuBar();
   JMenu menu = new JMenu("File");
   JMenuItem fileDigestItem = new JMenuItem("File digest");
   fileDigestItem.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent event) {
       loadFile();
     }
   });
   menu.add(fileDigestItem);
   JMenuItem textDigestItem = new JMenuItem("Text area digest");
   textDigestItem.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent event) {
       String m = message.getText();
       computeDigest(m.getBytes());
     }
   });
   menu.add(textDigestItem);
   menuBar.add(menu);
   setJMenuBar(menuBar);
 }
 public void addCheckBox(Container c, String name, ButtonGroup g,
     boolean selected, ActionListener listener) {
   JCheckBox b = new JCheckBox(name, selected);
   c.add(b);
   g.add(b);
   b.addActionListener(listener);
 }
 public void setAlgorithm(String alg) {
   try {
     currentAlgorithm = MessageDigest.getInstance(alg);
     digest.setText("");
   } catch (NoSuchAlgorithmException e) {
     digest.setText("" + e);
   }
 }
 public void loadFile() {
   JFileChooser chooser = new JFileChooser();
   chooser.setCurrentDirectory(new File("."));
   int r = chooser.showOpenDialog(this);
   if (r == JFileChooser.APPROVE_OPTION) {
     String name = chooser.getSelectedFile().getAbsolutePath();
     computeDigest(loadBytes(name));
   }
 }
 public byte[] loadBytes(String name) {
   FileInputStream in = null;
   try {
     in = new FileInputStream(name);
     ByteArrayOutputStream buffer = new ByteArrayOutputStream();
     int ch;
     while ((ch = in.read()) != -1)
       buffer.write(ch);
     return buffer.toByteArray();
   } catch (IOException e) {
     if (in != null) {
       try {
         in.close();
       } catch (IOException e2) {
       }
     }
     return null;
   }
 }
 public void computeDigest(byte[] b) {
   currentAlgorithm.reset();
   currentAlgorithm.update(b);
   byte[] hash = currentAlgorithm.digest();
   String d = "";
   for (int i = 0; i < hash.length; i++) {
     int v = hash[i] & 0xFF;
     if (v < 16)
       d += "0";
     d += Integer.toString(v, 16).toUpperCase() + " ";
   }
   digest.setText(d);
 }
 private JTextArea message = new JTextArea();
 private JTextField digest = new JTextField();
 private MessageDigest currentAlgorithm;

}

      </source>