001    /* SecretKeyFactory.java -- Factory for creating secret keys.
002       Copyright (C) 2004  Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package javax.crypto;
040    
041    import gnu.java.security.Engine;
042    
043    import java.lang.reflect.InvocationTargetException;
044    import java.security.InvalidKeyException;
045    import java.security.NoSuchAlgorithmException;
046    import java.security.NoSuchProviderException;
047    import java.security.Provider;
048    import java.security.Security;
049    import java.security.spec.InvalidKeySpecException;
050    import java.security.spec.KeySpec;
051    
052    /**
053     * A secret key factory translates {@link SecretKey} objects to and from
054     * {@link java.security.spec.KeySpec} objects, and can translate between
055     * different vendors' representations of {@link SecretKey} objects (for
056     * security or semantics; whichever applies).
057     *
058     * @author Casey Marshall (csm@gnu.org)
059     * @since 1.4
060     * @see SecretKey
061     */
062    public class SecretKeyFactory
063    {
064    
065      // Constants and fields.
066      // ------------------------------------------------------------------------
067    
068      private static final String SERVICE = "SecretKeyFactory";
069    
070      /** The underlying factory implementation. */
071      private SecretKeyFactorySpi skfSpi;
072    
073      /** The provider of the implementation. */
074      private Provider provider;
075    
076      /** The name of the algorithm. */
077      private String algorithm;
078    
079      // Constructor.
080      // ------------------------------------------------------------------------
081    
082      /**
083       * Create a new secret key factory.
084       *
085       * @param skfSpi   The underlying factory implementation.
086       * @param provider The provider.
087       * @param algorithm The algorithm name.
088       */
089      protected SecretKeyFactory(SecretKeyFactorySpi skfSpi, Provider provider,
090                                 String algorithm)
091      {
092        this.skfSpi = skfSpi;
093        this.provider = provider;
094        this.algorithm = algorithm;
095      }
096    
097      /**
098       * Create a new secret key factory from the first appropriate instance.
099       *
100       * @param algorithm The algorithm name.
101       * @return The appropriate key factory, if found.
102       * @throws NoSuchAlgorithmException If no provider implements the specified
103       *           algorithm.
104       * @throws IllegalArgumentException if <code>algorithm</code> is
105       *           <code>null</code> or is an empty string.
106       */
107      public static final SecretKeyFactory getInstance(String algorithm)
108          throws NoSuchAlgorithmException
109      {
110        Provider[] p = Security.getProviders();
111        NoSuchAlgorithmException lastException = null;
112        for (int i = 0; i < p.length; i++)
113          try
114            {
115              return getInstance(algorithm, p[i]);
116            }
117          catch (NoSuchAlgorithmException x)
118            {
119              lastException = x;
120            }
121          if (lastException != null)
122            throw lastException;
123          throw new NoSuchAlgorithmException(algorithm);
124      }
125    
126      /**
127       * Create a new secret key factory from the named provider.
128       *
129       * @param algorithm The algorithm name.
130       * @param provider The provider name.
131       * @return The appropriate key factory, if found.
132       * @throws NoSuchAlgorithmException If the named provider does not implement
133       *           the algorithm.
134       * @throws NoSuchProviderException If the named provider does not exist.
135       * @throws IllegalArgumentException if either <code>algorithm</code> or
136       *           <code>provider</code> is <code>null</code>, or if
137       *           <code>algorithm</code> is an empty string.
138       */
139      public static final SecretKeyFactory getInstance(String algorithm,
140                                                       String provider)
141          throws NoSuchAlgorithmException, NoSuchProviderException
142      {
143        if (provider == null)
144          throw new IllegalArgumentException("provider MUST NOT be null");
145        Provider p = Security.getProvider(provider);
146        if (p == null)
147          throw new NoSuchProviderException(provider);
148        return getInstance(algorithm, p);
149      }
150    
151      /**
152       * Create a new secret key factory from the specified provider.
153       *
154       * @param algorithm The algorithm name.
155       * @param provider The provider.
156       * @return The appropriate key factory, if found.
157       * @throws NoSuchAlgorithmException If the provider does not implement the
158       *           algorithm.
159       * @throws IllegalArgumentException if either <code>algorithm</code> or
160       *           <code>provider</code> is <code>null</code>, or if
161       *           <code>algorithm</code> is an empty string.
162       */
163      public static final SecretKeyFactory getInstance(String algorithm,
164                                                       Provider provider)
165          throws NoSuchAlgorithmException
166      {
167        StringBuilder sb = new StringBuilder("SecretKeyFactory algorithm [")
168            .append(algorithm).append("] from provider[")
169            .append(provider).append("] could not be created");
170        Throwable cause;
171        try
172          {
173            Object spi = Engine.getInstance(SERVICE, algorithm, provider);
174            return new SecretKeyFactory((SecretKeyFactorySpi) spi, provider, algorithm);
175          }
176        catch (InvocationTargetException x)
177          {
178            cause = x.getCause();
179            if (cause instanceof NoSuchAlgorithmException)
180              throw (NoSuchAlgorithmException) cause;
181            if (cause == null)
182              cause = x;
183          }
184        catch (ClassCastException x)
185          {
186            cause = x;
187          }
188        NoSuchAlgorithmException x = new NoSuchAlgorithmException(sb.toString());
189        x.initCause(cause);
190        throw x;
191      }
192    
193      /**
194       * Generate a secret key from a key specification, if possible.
195       *
196       * @param keySpec The key specification.
197       * @return The secret key.
198       * @throws java.security.InvalidKeySpecException If the key specification
199       *         cannot be transformed into a secret key.
200       */
201      public final SecretKey generateSecret(KeySpec keySpec)
202        throws InvalidKeySpecException
203      {
204        return skfSpi.engineGenerateSecret(keySpec);
205      }
206    
207      /**
208       * Get the algorithm name.
209       *
210       * @return The algorithm name.
211       */
212      public final String getAlgorithm()
213      {
214        return algorithm;
215      }
216    
217      /**
218       * Get the key specification from a secret key.
219       *
220       * @param key     The secret key.
221       * @param keySpec The target key specification class.
222       * @return The key specification.
223       * @throws java.security.spec.InvalidKeySpecException If the secret key cannot
224       *         be transformed into the specified key specification.
225       */
226      public final KeySpec getKeySpec(SecretKey key, Class keySpec)
227        throws InvalidKeySpecException
228      {
229        return skfSpi.engineGetKeySpec(key, keySpec);
230      }
231    
232      /**
233       * Get the provider of this implementation.
234       *
235       * @return The provider.
236       */
237      public final Provider getProvider()
238      {
239        return provider;
240      }
241    
242      /**
243       * Translate a secret key into another form.
244       *
245       * @param key The key to translate.
246       * @return The translated key.
247       * @throws java.security.InvalidKeyException If the argument cannot be
248       *         translated.
249       */
250      public final SecretKey translateKey(SecretKey key)
251        throws InvalidKeyException
252      {
253        return skfSpi.engineTranslateKey(key);
254      }
255    }