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9.7

Java Encryption - DES

Asked by Valleriani in Java Programming Language, Encryption for Network Security, Miscellaneous Programming

I am reading up on the DES encryption here: http://www.devx.com/Java/10MinuteSolution/21385/1954

And I wanted to use it because its fairly easy and contained a file/test file to try them out. Simple string encrypting is what I'm after in java.

However using the code below which is in the page (StringEncrypter.Class), gives me a error when I use it for 'importing'. However, the actual script DOES compile (With a few minor 'base64' warnings, but nothing that should effect it from actually being used. The error is:

C:\SF\bin>javac test.java -cp sfinfo.jar
test.java:1: cannot access sf.io.StringEncrypter
bad class file: sf\io\StringEncrypter.class(sf\io:StringEncrypter.class)
class file contains wrong class: StringEncrypter
Please remove or make sure it appears in the correct subdirectory of the classpath.
import sf.io.StringEncrypter;

The file is located in a jar file, at sf/io/StringEncrypter.class, and I call it using import sf.io.StringEncrypter

There are other files in sf/io that work fine, such as sf.io.ImportData, which imports just fine. Just using a simple file that 'imports' and has a blank main class, it gives the error.

Any ideas or solutions that can be done with the current encryption code in java? Any ideas on this error? Thanks!

To be clear. The StringEncrypter.java compiles fine, but when I try to use it in a file for and use 'import' its not working and giving that error on compile.

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             package examples;
 
import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.KeySpec;
 
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.DESedeKeySpec;
 
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
 
public class StringEncrypter
{
     
     public static final String DESEDE_ENCRYPTION_SCHEME = "DESede";
     public static final String DES_ENCRYPTION_SCHEME = "DES";
     public static final String               DEFAULT_ENCRYPTION_KEY     = "This is a fairly long phrase used to encrypt";
     
     private KeySpec                    keySpec;
     private SecretKeyFactory     keyFactory;
     private Cipher                    cipher;
     
     private static final String     UNICODE_FORMAT               = "UTF8";
 
     public StringEncrypter( String encryptionScheme ) throws EncryptionException
     {
          this( encryptionScheme, DEFAULT_ENCRYPTION_KEY );
     }
 
     public StringEncrypter( String encryptionScheme, String encryptionKey )
               throws EncryptionException
     {
 
          if ( encryptionKey == null )
                    throw new IllegalArgumentException( "encryption key was null" );
          if ( encryptionKey.trim().length() < 24 )
                    throw new IllegalArgumentException(
                              "encryption key was less than 24 characters" );
 
          try
          {
               byte[] keyAsBytes = encryptionKey.getBytes( UNICODE_FORMAT );
 
               if ( encryptionScheme.equals( DESEDE_ENCRYPTION_SCHEME) )
               {
                    keySpec = new DESedeKeySpec( keyAsBytes );
               }
               else if ( encryptionScheme.equals( DES_ENCRYPTION_SCHEME ) )
               {
                    keySpec = new DESKeySpec( keyAsBytes );
               }
               else
               {
                    throw new IllegalArgumentException( "Encryption scheme not supported: "
                                                                 + encryptionScheme );
               }
 
               keyFactory = SecretKeyFactory.getInstance( encryptionScheme );
               cipher = Cipher.getInstance( encryptionScheme );
 
          }
          catch (InvalidKeyException e)
          {
               throw new EncryptionException( e );
          }
          catch (UnsupportedEncodingException e)
          {
               throw new EncryptionException( e );
          }
          catch (NoSuchAlgorithmException e)
          {
               throw new EncryptionException( e );
          }
          catch (NoSuchPaddingException e)
          {
               throw new EncryptionException( e );
          }
 
     }
 
     public String encrypt( String unencryptedString ) throws EncryptionException
     {
          if ( unencryptedString == null || unencryptedString.trim().length() == 0 )
                    throw new IllegalArgumentException(
                              "unencrypted string was null or empty" );
 
          try
          {
               SecretKey key = keyFactory.generateSecret( keySpec );
               cipher.init( Cipher.ENCRYPT_MODE, key );
               byte[] cleartext = unencryptedString.getBytes( UNICODE_FORMAT );
               byte[] ciphertext = cipher.doFinal( cleartext );
 
               BASE64Encoder base64encoder = new BASE64Encoder();
               return base64encoder.encode( ciphertext );
          }
          catch (Exception e)
          {
               throw new EncryptionException( e );
          }
     }
 
     public String decrypt( String encryptedString ) throws EncryptionException
     {
          if ( encryptedString == null || encryptedString.trim().length() <= 0 )
                    throw new IllegalArgumentException( "encrypted string was null or empty" );
 
          try
          {
               SecretKey key = keyFactory.generateSecret( keySpec );
               cipher.init( Cipher.DECRYPT_MODE, key );
               BASE64Decoder base64decoder = new BASE64Decoder();
               byte[] cleartext = base64decoder.decodeBuffer( encryptedString );
               byte[] ciphertext = cipher.doFinal( cleartext );
 
               return bytes2String( ciphertext );
          }
          catch (Exception e)
          {
               throw new EncryptionException( e );
          }
     }
 
     private static String bytes2String( byte[] bytes )
     {
          StringBuffer stringBuffer = new StringBuffer();
          for (int i = 0; i < bytes.length; i++)
          {
               stringBuffer.append( (char) bytes[i] );
          }
          return stringBuffer.toString();
     }
 
     public static class EncryptionException extends Exception
     {
          public EncryptionException( Throwable t )
          {
               super( t );
          }
     }
}
           
         

20090824-EE-VQP-74 - Hierarchy / EE_QW_3_20080625

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Java Encryption - DES

Asked by Valleriani in Java Programming Language, Encryption for Network Security, Miscellaneous Programming

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