Java Encryption - DES

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 );
          }
     }
}
                                  

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