chiffrement dechiffrement symétrique

**merlinlenchanteur971** · 28/09/2007, 15h17

Bonjour,pour effectuer mon chiffrement dechiffrement de fichier, j'utilise la classe suivante. Cependant j'ai un probleme : quand je fais le chiffrement et que je dechiffre le fichier obtenu sur une autre machine, ca marche plus alors que quand je fait le dechiffrement en local (c'est a dire sur la machine sur laquelle j'ai chiffré le document) ca marche.

Que faire pour regler ce probleme ?

Code :

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/*
 * DesEncypter.java
 *
 * Created on 26 septembre 2007, 11:22
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */
 
package Cipher;
 
 
import javax.crypto.*;
import javax.crypto.spec.*;
 
import java.io.*;
import IHM.*;
import javax.swing.JFileChooser;
/**
 *
 * @author user
 */
 
 
 
public class Encrypter {
 
 
    // Buffer used to transport the bytes from one stream to another
    byte[] buf = new byte[1024];
 
    //Secret key used to cipher a stream
    public SecretKeySpec key;
 
 
    /**
     * Creates a new instance of DesEncypter
     */
    public Encrypter() {
    }
 
 
    public void SetSecretKeySpec(String stringKey, String algorithm) {
        try {
            key = new SecretKeySpec(stringKey.getBytes("ISO-8859-1"),algorithm);
            System.out.println("Create a "+stringKey.getBytes("ISO-8859-1").length+" key " + stringKey );
        } catch (UnsupportedEncodingException ex) {
            ex.printStackTrace();
        }
 
    }
 
    //main ciphering function
    public void encrypt(InputStream in, OutputStream out, String algorithm) {
        try {
 
            // bytes read from in will be encrypted
            System.out.println("inputStream before encryption is ==>"+in);
            in = getEncryptedInputStream(in,algorithm);
            System.out.println("inputStream after encryption is ==>"+in);
 
            // Read in the cleartext bytes and write to out to encrypt
            int numRead = 0;
            while ((numRead = in.read(buf)) >= 0) {
                out.write(buf, 0, numRead);
            }
            out.close();
        } catch (java.io.IOException e) {
            e.printStackTrace();
        }
    }
 
    //main deciphering fonction
    public void decrypt(InputStream in, OutputStream out,String algorithm) {
        try {
 
            // Bytes written to out will be decrypted
            System.out.println("outputStream before decryption is ==>"+out);
            out = getDecryptedOutputStream(out,algorithm);
            System.out.println("outputStream after decryption is ==>"+out);
 
            // Read in the decrypted bytes and write the cleartext to out
            int numRead = 0;
            while ((numRead = in.read(buf)) >= 0) {
                out.write(buf, 0, numRead);
            }
            out.close();
        } catch (java.io.IOException e) {
            e.printStackTrace();
        }
    }
 
 
    private InputStream getEncryptedInputStream(InputStream in , String algorithm) {
        System.out.println("\n inside getEncryptedInputStream before encryption in==>"+in);
        try {
            Cipher ecipher = Cipher.getInstance(algorithm);
            ecipher.init(Cipher.ENCRYPT_MODE, key);
            in = new CipherInputStream(in, ecipher);
 
        } catch (javax.crypto.NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (java.security.NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (java.security.InvalidKeyException e) {
            e.printStackTrace();
        }
        System.out.println("\n inside getEncryptedInputStream after encryption in==>"+in);
        return in;
    }
 
 
 
    private OutputStream getDecryptedOutputStream(OutputStream out, String algorithm) {
        System.out.println("\n inside getDecryptedOutputStream before decryption out==>"+out);
        try {
            Cipher dcipher = Cipher.getInstance(algorithm);
            dcipher.init(Cipher.DECRYPT_MODE, key);
            out = new CipherOutputStream(out, dcipher);
        } catch (javax.crypto.NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (java.security.NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (java.security.InvalidKeyException e) {
            e.printStackTrace();
        }
        System.out.println("\n inside getDecryptedOutputStream after decryption out==>"+out);
        return out;
    }
}

le code du GUI pour chiffrer

Code :

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/*
 * CipherGUI.java
 *
 * Created on 27 septembre 2007, 09:19
 */
 
package IHM;
 
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import javax.swing.JFileChooser;
import Cipher.*;
 
/**
 *
 * @author  user
 */
public class CipherGUI extends javax.swing.JFrame {
 
    String filePath;
    //length of the secretkey
    int secretKeyLength;
    int conventionalSecretKeyLengthInBytes;
 
    //name of the algorithm AES,DES,3DES,Blowfish
    String algorithm;
    // the secret key use to cipher a file
    String secretKey;
 
 
    /** Creates new form CipherGUI */
    public CipherGUI() {
        initComponents();
        _secretKey_textField.setEditable(false);
        filePath=null;
    }
 
    /** 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.
     */
    // <editor-fold defaultstate="collapsed" desc=" Generated Code ">                          
    private void initComponents() {
        _filename_button = new javax.swing.JButton();
        _cipher_button = new javax.swing.JButton();
        _algorithm_comboBox = new javax.swing.JComboBox();
        _secretKey_textField = new javax.swing.JTextField();
        _filename_label = new javax.swing.JLabel();
        jScrollPane1 = new javax.swing.JScrollPane();
        _infos_jtextArea = new javax.swing.JTextArea();
        _algorithm_length_comboBox = new javax.swing.JComboBox();
        _secretKey_label = new javax.swing.JLabel();
        _analyse_button = new javax.swing.JButton();
 
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                formMouseClicked(evt);
            }
        });
 
        _filename_button.setText("Choisir le fichier \u00e0 chiffrer");
        _filename_button.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                _filename_buttonMouseClicked(evt);
            }
        });
 
        _cipher_button.setText("Chiffrer");
        _cipher_button.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                _cipher_buttonMouseClicked(evt);
            }
        });
 
        _algorithm_comboBox.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "", "aes", "blowfish", "des", "desede" }));
        _algorithm_comboBox.addItemListener(new java.awt.event.ItemListener() {
            public void itemStateChanged(java.awt.event.ItemEvent evt) {
                _algorithm_comboBoxItemStateChanged(evt);
            }
        });
 
        _secretKey_textField.setHorizontalAlignment(javax.swing.JTextField.CENTER);
        _secretKey_textField.setText("A1B2C3D4E5F6G7H8I9J10K11L12M13N14O15P16Q17R18");
 
        _filename_label.setText("Selected filename is not defined");
 
        _infos_jtextArea.setColumns(20);
        _infos_jtextArea.setRows(5);
        jScrollPane1.setViewportView(_infos_jtextArea);
 
        _algorithm_length_comboBox.addItemListener(new java.awt.event.ItemListener() {
            public void itemStateChanged(java.awt.event.ItemEvent evt) {
                _algorithm_length_comboBoxItemStateChanged(evt);
            }
        });
 
        _secretKey_label.setText("Secret key length not defined");
 
        _analyse_button.setText("Analyser");
        _analyse_button.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                _analyse_buttonMouseClicked(evt);
            }
        });
 
        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(_filename_button, javax.swing.GroupLayout.DEFAULT_SIZE, 382, Short.MAX_VALUE)
                            .addComponent(_filename_label, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 382, Short.MAX_VALUE)
                            .addGroup(layout.createSequentialGroup()
                                .addGap(35, 35, 35)
                                .addComponent(_algorithm_comboBox, javax.swing.GroupLayout.PREFERRED_SIZE, 123, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addGap(49, 49, 49)
                                .addComponent(_algorithm_length_comboBox, javax.swing.GroupLayout.PREFERRED_SIZE, 129, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 46, javax.swing.GroupLayout.PREFERRED_SIZE)))
                        .addGap(25, 25, 25))
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(_secretKey_textField, javax.swing.GroupLayout.DEFAULT_SIZE, 382, Short.MAX_VALUE)
                        .addGap(25, 25, 25))
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 382, Short.MAX_VALUE)
                        .addGap(25, 25, 25))
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(_cipher_button, javax.swing.GroupLayout.DEFAULT_SIZE, 382, Short.MAX_VALUE)
                        .addGap(25, 25, 25))
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(_secretKey_label, javax.swing.GroupLayout.DEFAULT_SIZE, 185, Short.MAX_VALUE)
                        .addGap(222, 222, 222))
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(_analyse_button, javax.swing.GroupLayout.DEFAULT_SIZE, 382, Short.MAX_VALUE)
                        .addGap(25, 25, 25))))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(20, 20, 20)
                .addComponent(_filename_button)
                .addGap(16, 16, 16)
                .addComponent(_filename_label)
                .addGap(15, 15, 15)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(_algorithm_comboBox, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(_algorithm_length_comboBox, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 34, Short.MAX_VALUE)
                .addComponent(_analyse_button)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(_secretKey_label)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(_secretKey_textField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(30, 30, 30)
                .addComponent(_cipher_button)
                .addGap(23, 23, 23)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(48, 48, 48))
        );
        pack();
    }// </editor-fold>                        
 
    private void _analyse_buttonMouseClicked(java.awt.event.MouseEvent evt) {                                             
// TODO add your handling code here:
        if (!_algorithm_length_comboBox.getSelectedItem().toString().equals("taille")) {
            int conventionalSecretKeyLengthInBits = Integer.parseInt( _algorithm_length_comboBox.getSelectedItem().toString());
            conventionalSecretKeyLengthInBytes = conventionalSecretKeyLengthInBits/8;
            _secretKey_label.setText("Entrer une cle de longeur "+conventionalSecretKeyLengthInBytes);
            _secretKey_textField.setEditable(true);
        }
    }                                            
 
    private void _algorithm_length_comboBoxItemStateChanged(java.awt.event.ItemEvent evt) {                                                            
// TODO add your handling code here:
    }                                                           
 
    private void _algorithm_comboBoxItemStateChanged(java.awt.event.ItemEvent evt) {                                                     
// TODO add your handling code here:
        algorithm = _algorithm_comboBox.getSelectedItem().toString();
 
        if (algorithm.equals("aes")) {
            _algorithm_length_comboBox.removeAllItems();
            _algorithm_length_comboBox.addItem("taille");
            _algorithm_length_comboBox.addItem("128");
            _algorithm_length_comboBox.addItem("192");
            _algorithm_length_comboBox.addItem("256");
        }
        if (algorithm.equals("des")) {
            _algorithm_length_comboBox.removeAllItems();
            _algorithm_length_comboBox.addItem("taille");
            _algorithm_length_comboBox.addItem("64");
        }
        if (algorithm.equals("desede")) {
            _algorithm_length_comboBox.removeAllItems();
            _algorithm_length_comboBox.addItem("taille");
            _algorithm_length_comboBox.addItem("192");
        }
        if (algorithm.equals("blowfish")) {
            _algorithm_length_comboBox.removeAllItems();
            _algorithm_length_comboBox.addItem("taille");
            _algorithm_length_comboBox.addItem("128");
            _algorithm_length_comboBox.addItem("192");
            _algorithm_length_comboBox.addItem("256");
            _algorithm_length_comboBox.addItem("320");
            _algorithm_length_comboBox.addItem("384");
            _algorithm_length_comboBox.addItem("448");
        }
    }                                                    
 
    private void _filename_buttonMouseClicked(java.awt.event.MouseEvent evt) {                                              
// TODO add your handling code here:
        JFileChooser choix = new JFileChooser();
        choix.setAccessory(new FilePreview(choix));
        int retour = choix.showOpenDialog(this);
        if (retour == JFileChooser.APPROVE_OPTION) {
            // un fichier a été choisi (sortie par Ouvrir)
            filePath=choix.getSelectedFile().getAbsolutePath();// chemin absolu du fichier choisi
            this._filename_label.setText("fichier a chiffrer "+filePath);
        } else ; // pas de fichier choisi
    }                                             
 
    private void _cipher_buttonMouseClicked(java.awt.event.MouseEvent evt) {                                            
// TODO add your handling code here:
        algorithm = _algorithm_comboBox.getSelectedItem().toString();
        secretKey = _secretKey_textField.getText();
        secretKeyLength = secretKey.length();
 
        if (secretKeyLength > conventionalSecretKeyLengthInBytes) {
            secretKey = secretKey.substring(0,conventionalSecretKeyLengthInBytes);
            _infos_jtextArea.setText("la secret key est trop longue et sera tronquee. Secretkey utilisee\n"+secretKey +"\n"+secretKey.length());
        }
 
        if (secretKeyLength < conventionalSecretKeyLengthInBytes) {
            int temp = conventionalSecretKeyLengthInBytes - secretKeyLength;
            String concat="0";
            for (int i = 1 ; i < temp ; i++)
                concat = concat+"0";
            secretKey = secretKey + concat;
            System.out.println(secretKeyLength +" + "+concat.length());
            _infos_jtextArea.setText("la secret key est trop courte des 0 seront ajoutes.\nSecretkey utilisee\n"+secretKey +"\n"+secretKey.length());
        }
 
 
        if (secretKey.length() == conventionalSecretKeyLengthInBytes ) {
            _infos_jtextArea.setText("longeur de clé correcte \n"+secretKey +"\n"+secretKey.length());
            // Create encrypter/decrypter class
            Encrypter encrypter = new Encrypter();
            encrypter.SetSecretKeySpec(secretKey,algorithm);
            // Encrypt
            if(!filePath.equals(null)) {
                System.out.println("encrypting the file");
                try {
                    encrypter.encrypt(new FileInputStream(filePath), new FileOutputStream(filePath+algorithm+(conventionalSecretKeyLengthInBytes*8)),algorithm);
                } catch (FileNotFoundException ex) {
                    ex.printStackTrace();
                }
            } else
                _infos_jtextArea.setText("pas de fichier selectionne");
 
        } else
            _infos_jtextArea.setText(secretKey.length()+ " requiere " +conventionalSecretKeyLengthInBytes);
 
 
    }                                           
 
    private void formMouseClicked(java.awt.event.MouseEvent evt) {                                  
// TODO add your handling code here:
 
    }                                 
 
    /**
     * @param args the command line arguments
     */
    public void Launch() {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new CipherGUI().setVisible(true);
            }
        });
    }
 
    // Variables declaration - do not modify                     
    private javax.swing.JComboBox _algorithm_comboBox;
    private javax.swing.JComboBox _algorithm_length_comboBox;
    private javax.swing.JButton _analyse_button;
    private javax.swing.JButton _cipher_button;
    private javax.swing.JButton _filename_button;
    private javax.swing.JLabel _filename_label;
    private javax.swing.JTextArea _infos_jtextArea;
    private javax.swing.JLabel _secretKey_label;
    private javax.swing.JTextField _secretKey_textField;
    private javax.swing.JScrollPane jScrollPane1;
    // End of variables declaration                   
 
}

pour dechiffrer il suffit de modifier le GUI du chiffrement et notament la ligne encrypter.encrypt .. par encrypter.decrypt(cipherSource, destination,algo)

**Razgriz** · 29/09/2007, 12h21

Grrrrrrrrrrr, je sens que je vais faire un carnage...

J'ai posté des classes pour le cryptage dans la section contribuez (Posetz vos sources java) , il y a tout ce dont tu as besoin pour résoudre ton problème, peut-être qu'en cherchant tu aurais trouvé... Ton erreur vient d'une mauvaise utilisation de la classe Cipher. Et ensuite le DES est un algorithme obsolète qui n'est plus considéré comme sur depuis longtemps. Utilise ma classe SymetricEncryptor (tu auras besoin de CipherEncryptor et de FileEncryptor aussi).

Sinon de manière plus aimable je me méfierais de la classe CipherIn/Outputstream, elle contient des bugs pour le cryptage de certains algorithmes sous certaines conditions, comme le RSA, il faut donc l'utiliser avec précaution.

Sur ce, a+, j'espère avoir répondu à tes questions.

chiffrement dechiffrement symétrique

Sécurité Java

Vue hybride

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