Decryption

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 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

package Encrypt;


import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFileChooser;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.util.Arrays;
import javax.crypto.Cipher;
/**
 *
 * @author Proking
 */
public class DecryptForm extends javax.swing.JInternalFrame {
    String filename = "";
    String pText = "";

 /*
    //
    */
      public static final String ALGORITHM = "RSA";

  /**
   * String to hold the name of the private key file.
   */
  public static final String PRIVATE_KEY_FILE = "C:/keys/private.key";

  /**
   * String to hold name of the public key file.
   */
  public static final String PUBLIC_KEY_FILE = "C:/keys/public.key";

  /**
   * Generate key which contains a pair of private and public key using 1024
   * bytes. Store the set of keys in Prvate.key and Public.key files.
   *
   * @throws NoSuchAlgorithmException
   * @throws IOException
   * @throws FileNotFoundException
   */
  public static void generateKey() {
    try {
      final KeyPairGenerator keyGen = KeyPairGenerator.getInstance(ALGORITHM);
      keyGen.initialize(1024);
      final KeyPair key = keyGen.generateKeyPair();

      File privateKeyFile = new File(PRIVATE_KEY_FILE);
      File publicKeyFile = new File(PUBLIC_KEY_FILE);

      // Create files to store public and private key
      if (privateKeyFile.getParentFile() != null) {
        privateKeyFile.getParentFile().mkdirs();
      }
      privateKeyFile.createNewFile();

      if (publicKeyFile.getParentFile() != null) {
        publicKeyFile.getParentFile().mkdirs();
      }
      publicKeyFile.createNewFile();

      // Saving the Public key in a file
      ObjectOutputStream publicKeyOS = new ObjectOutputStream(
          new FileOutputStream(publicKeyFile));
      publicKeyOS.writeObject(key.getPublic());
      publicKeyOS.close();

      // Saving the Private key in a file
      ObjectOutputStream privateKeyOS = new ObjectOutputStream(
          new FileOutputStream(privateKeyFile));
      privateKeyOS.writeObject(key.getPrivate());
      privateKeyOS.close();
    } catch (Exception e) {
      e.printStackTrace();
    }

  }

  /**
   * The method checks if the pair of public and private key has been generated.
   *
   * @return flag indicating if the pair of keys were generated.
   */
  public static boolean areKeysPresent() {

    File privateKey = new File(PRIVATE_KEY_FILE);
    File publicKey = new File(PUBLIC_KEY_FILE);

    if (privateKey.exists() && publicKey.exists()) {
      return true;
    }
    return false;
  }

  /**
   * Encrypt the plain text using public key.
   *
   * @param text
   *          : original plain text
   * @param key
   *          :The public key
   * @return Encrypted text
   * @throws java.lang.Exception
   */
  public static byte[] encrypt(String text, PublicKey key) {
    byte[] cipherText = null;
    try {
      // get an RSA cipher object and print the provider
      final Cipher cipher = Cipher.getInstance(ALGORITHM);
      // encrypt the plain text using the public key
      cipher.init(Cipher.ENCRYPT_MODE, key);
      cipherText = cipher.doFinal(text.getBytes());
    } catch (Exception e) {
      e.printStackTrace();
    }
    return cipherText;
  }

  /**
   * Decrypt text using private key.
   *
   * @param text
   *          :encrypted text
   * @param key
   *          :The private key
   * @return plain text
   * @throws java.lang.Exception
   */
  public static String decrypt(byte[] text, PrivateKey key) {
    byte[] dectyptedText = null;
    try {
      // get an RSA cipher object and print the provider
      final Cipher cipher = Cipher.getInstance(ALGORITHM);
      // decrypt the text using the private key
      cipher.init(Cipher.DECRYPT_MODE, key);
      System.out.println("Text in Decrypt"+ text);
      dectyptedText = cipher.doFinal(text);

    } catch (Exception ex) {
      ex.printStackTrace();
      System.out.println("Blah blah: "+ex);
    }
    System.out.println("Decrypter Text: " +dectyptedText);
    return new String(dectyptedText);
  }


    /**
     * Creates new form DecryptForm
     */
    public DecryptForm() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        dtextbox = new javax.swing.JTextField();
        Dbutton = new javax.swing.JButton();
        DecryptB = new javax.swing.JButton();
        jLabel2 = new javax.swing.JLabel();
        saveintb = new javax.swing.JTextField();
        Dbutton1 = new javax.swing.JButton();

        jLabel1.setText("File");

        dtextbox.setEditable(false);

        Dbutton.setText("Browse");
        Dbutton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                DbuttonActionPerformed(evt);
            }
        });

        DecryptB.setText("DeCrypt");
        DecryptB.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                DecryptBActionPerformed(evt);
            }
        });

        jLabel2.setText("Save In");

        saveintb.setEditable(false);

        Dbutton1.setText("Browse");
        Dbutton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                Dbutton1ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(71, 71, 71)
                        .addComponent(saveintb)
                        .addGap(10, 10, 10)
                        .addComponent(Dbutton1))
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                            .addGroup(layout.createSequentialGroup()
                                .addContainerGap(218, Short.MAX_VALUE)
                                .addComponent(DecryptB))
                            .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                                .addGap(24, 24, 24)
                                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                                    .addComponent(jLabel2)
                                    .addComponent(jLabel1))
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                .addComponent(dtextbox)))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(Dbutton)))
                .addGap(26, 26, 26))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(48, 48, 48)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel1)
                    .addComponent(dtextbox, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(Dbutton))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel2)
                    .addComponent(saveintb, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(Dbutton1))
                .addGap(30, 30, 30)
                .addComponent(DecryptB)
                .addContainerGap(120, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>

    private void DbuttonActionPerformed(java.awt.event.ActionEvent evt) {

    // TODO add your handling code here:
        JFileChooser chooser = new JFileChooser();
        chooser.showOpenDialog(null);
        File f = chooser.getSelectedFile();
        filename = f.getAbsolutePath();
        dtextbox.setText(filename);

        //String ext="";
        //int mid= filename.lastIndexOf(".");
        //ext=filename.substring(mid+1,filename.length());
        //System.out.println("Extension ="+ext);
        //JOptionPane.showConfirmDialog(null, ext);
    }

    private void DecryptBActionPerformed(java.awt.event.ActionEvent evt) {
        // TODO add your handling code here:
        final String plainText;
        if (!areKeysPresent()) {
        // Method generates a pair of keys using the RSA algorithm and stores it
        // in their respective files
        generateKey();
      }
        if(dtextbox.getText().equals(""))
        {
            final JPanel panel = new JPanel();
            JOptionPane.showMessageDialog(panel, "Could not open file", "Error", JOptionPane.ERROR_MESSAGE);
            //JOptionPane.showMessageDialog(JOptionPane.ERROR_MESSAGE, "Error: No File Selected");
            return;
        }
        /*if(saveintb.getText().equals(""))
        {
            final JPanel panel = new JPanel();
            JOptionPane.showMessageDialog(panel, "Could not open file", "Error", JOptionPane.ERROR_MESSAGE);
            //JOptionPane.showMessageDialog(JOptionPane.ERROR_MESSAGE, "Error: No File Selected");
            return;
        }*/
        String ext="";
        int mid= filename.lastIndexOf(".");
        ext=filename.substring(mid+1,filename.length());
        String fileString = "";
        try {
            // TODO add your handling code here:
            int i;
            FileInputStream fin = null;
            try {
                fin = new FileInputStream(filename);
            } catch (FileNotFoundException ex) {
                Logger.getLogger(EncryptForm.class.getName()).log(Level.SEVERE, null, ex);
            }
            do{
                i=fin.read();
                if(i!=-1)
                {
                    fileString +=(char) i;
                }
            }while(i!=-1);
            fin.close();
            //JOptionPane.showMessageDialog(null, fileString);
        } catch (IOException ex) {
        Logger.getLogger(EncryptForm.class.getName()).log(Level.SEVERE, null, ex);
        }
        byte[] bytes = fileString.getBytes();
        System.out.println("String to Bytes0: "+bytes);
        if(ext.equals("RSA"))
        {
            try {
                ObjectInputStream inputStream;


                inputStream = new ObjectInputStream(new FileInputStream(PRIVATE_KEY_FILE));
                final PrivateKey privateKey = (PrivateKey) inputStream.readObject();
                byte[] byteData = fileString.getBytes();
                JOptionPane.showMessageDialog(null, byteData);

                try
                {
                   JOptionPane.showMessageDialog(null, privateKey);
                   System.out.println("Private key: "+privateKey);
                    plainText = decrypt(byteData, privateKey);
                }
                catch(Exception ex)
                {
                    System.out.println(ex);
                    JOptionPane.showMessageDialog(null, ex);
                }
                pText = plainText;
            } catch (IOException | ClassNotFoundException ex) {
                Logger.getLogger(DecryptForm.class.getName()).log(Level.SEVERE, null, ex);
            }
            JOptionPane.showMessageDialog(null, "RSA Decryption Complete");
        }
        FileOutputStream fop = null;
    File file;
    try {
        file = new File("c:\\JavaFiles\\dfile.txt");
        fop = new FileOutputStream(file);
// if file doesnt exists, then create it

        if (!file.exists()) {
            file.createNewFile();
        }
 // get the content in bytes
        byte[] contentInBytes = pText.getBytes();
        fop.write(contentInBytes);
        fop.flush();
        fop.close();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            if (fop != null) {
                fop.close();
                        }
                } catch (IOException e) {
                    e.printStackTrace();
                }
    }//RSA Ends
    }

    private void Dbutton1ActionPerformed(java.awt.event.ActionEvent evt) {
        // TODO add your handling code here:
        JFileChooser chooser = new JFileChooser();
        chooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
        int returnVal = chooser.showOpenDialog(null);
        if(returnVal == JFileChooser.APPROVE_OPTION) {
        saveintb.setText(chooser.getSelectedFile().getAbsolutePath());
        }
    }


    // Variables declaration - do not modify
    private javax.swing.JButton Dbutton;
    private javax.swing.JButton Dbutton1;
    private javax.swing.JButton DecryptB;
    private javax.swing.JTextField dtextbox;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JTextField saveintb;
    // End of variables declaration
}