001/* KeyFactory.java --- Key Factory Class
002   Copyright (C) 1999, 2003, 2004  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.security;
040
041import gnu.java.lang.CPStringBuilder;
042
043import gnu.java.security.Engine;
044
045import java.lang.reflect.InvocationTargetException;
046import java.security.spec.InvalidKeySpecException;
047import java.security.spec.KeySpec;
048
049/**
050 * Key factories are used to convert keys (opaque cryptographic keys of type
051 * {@link Key}) into key specifications (transparent representations of the
052 * underlying key material).
053 * 
054 * <p>Key factories are bi-directional. They allow a key class to be converted
055 * into a key specification (key material) and back again. For example DSA
056 * public keys can be specified as <code>DSAPublicKeySpec</code> or
057 * <code>X509EncodedKeySpec</code>. A key factory translates these key
058 * specifications.</p>
059 *
060 * @since 1.2
061 * @see Key
062 * @see KeySpec
063 * @see java.security.spec.DSAPublicKeySpec
064 * @see java.security.spec.X509EncodedKeySpec
065   @author Mark Benvenuto
066 */
067public class KeyFactory
068{
069  /** The service name for key factories. */
070  private static final String KEY_FACTORY = "KeyFactory";
071
072  private KeyFactorySpi keyFacSpi;
073  private Provider provider;
074  private String algorithm;
075
076  /**
077   * Constructs a new instance of <code>KeyFactory</code> with the specified
078   * parameters.
079   * 
080   * @param keyFacSpi
081   *          the key factory to use.
082   * @param provider
083   *          the provider to use.
084   * @param algorithm
085   *          the name of the key algorithm to use.
086   */
087  protected KeyFactory(KeyFactorySpi keyFacSpi, Provider provider,
088                       String algorithm)
089  {
090    this.keyFacSpi = keyFacSpi;
091    this.provider = provider;
092    this.algorithm = algorithm;
093  }
094
095  /**
096   * Returns a new instance of <code>KeyFactory</code> representing the
097   * specified key factory.
098   * 
099   * @param algorithm the name of algorithm to use.
100   * @return a new instance repesenting the desired algorithm.
101   * @throws NoSuchAlgorithmException if the algorithm is not implemented by any
102   *           provider.
103   * @throws IllegalArgumentException if <code>algorithm</code> is
104   *           <code>null</code> or is an empty string.
105   */
106  public static KeyFactory getInstance(String algorithm)
107      throws NoSuchAlgorithmException
108  {
109    Provider[] p = Security.getProviders();
110    NoSuchAlgorithmException lastException = null;
111    for (int i = 0; i < p.length; i++)
112      try
113        {
114          return getInstance(algorithm, p[i]);
115        }
116      catch (NoSuchAlgorithmException x)
117        {
118          lastException = x;
119        }
120    if (lastException != null)
121      throw lastException;
122    throw new NoSuchAlgorithmException(algorithm);
123  }
124
125  /**
126   * Returns a new instance of <code>KeyFactory</code> representing the
127   * specified key factory from the specified provider.
128   * 
129   * @param algorithm the name of algorithm to use.
130   * @param provider the name of the provider to use.
131   * @return a new instance repesenting the desired algorithm.
132   * @throws NoSuchAlgorithmException if the algorithm is not implemented by the
133   *           named provider.
134   * @throws NoSuchProviderException if the named provider was not found.
135   * @throws IllegalArgumentException if either <code>algorithm</code> or
136   *           <code>provider</code> is <code>null</code> or empty.
137   */
138  public static KeyFactory getInstance(String algorithm, String provider)
139      throws NoSuchAlgorithmException, NoSuchProviderException
140  {
141    if (provider == null)
142      throw new IllegalArgumentException("provider MUST NOT be null");
143    provider = provider.trim();
144    if (provider.length() == 0)
145      throw new IllegalArgumentException("provider MUST NOT be empty");
146    Provider p = Security.getProvider(provider);
147    if (p == null)
148      throw new NoSuchProviderException(provider);
149    return getInstance(algorithm, p);
150  }
151
152  /**
153   * Returns a new instance of <code>KeyFactory</code> representing the
154   * specified key factory from the designated {@link Provider}.
155   * 
156   * @param algorithm the name of algorithm to use.
157   * @param provider the {@link Provider} to use.
158   * @return a new instance repesenting the desired algorithm.
159   * @throws NoSuchAlgorithmException if the algorithm is not implemented by
160   *           {@link Provider}.
161   * @throws IllegalArgumentException if either <code>algorithm</code> or
162   *           <code>provider</code> is <code>null</code>, or if
163   *           <code>algorithm</code> is an empty string.
164   * @since 1.4
165   * @see Provider
166   */
167  public static KeyFactory getInstance(String algorithm, Provider provider)
168      throws NoSuchAlgorithmException
169  {
170    CPStringBuilder sb = new CPStringBuilder("KeyFactory for algorithm [")
171        .append(algorithm).append("] from provider[")
172        .append(provider).append("] could not be created");
173    Throwable cause;
174    try
175      {
176        Object spi = Engine.getInstance(KEY_FACTORY, algorithm, provider);
177        return new KeyFactory((KeyFactorySpi) spi, provider, algorithm);
178      }
179    catch (InvocationTargetException x)
180      {
181        cause = x.getCause();
182        if (cause instanceof NoSuchAlgorithmException)
183          throw (NoSuchAlgorithmException) cause;
184        if (cause == null)
185          cause = x;
186      }
187    catch (ClassCastException x)
188      {
189        cause = x;
190      }
191    NoSuchAlgorithmException x = new NoSuchAlgorithmException(sb.toString());
192    x.initCause(cause);
193    throw x;
194  }
195
196  /**
197   * Returns the {@link Provider} of this instance.
198   * 
199   * @return the {@link Provider} of this instance.
200   */
201  public final Provider getProvider()
202  {
203    return provider;
204  }
205
206  /**
207   * Returns the name of the algorithm used.
208   * 
209   * @return the name of the algorithm used.
210   */
211  public final String getAlgorithm()
212  {
213    return algorithm;
214  }
215
216  /**
217   * Generates a public key from the provided key specification.
218   * 
219   * @param keySpec
220   *          the key specification.
221   * @return the public key.
222   * @throws InvalidKeySpecException
223   *           if the key specification is invalid.
224   */
225  public final PublicKey generatePublic(KeySpec keySpec)
226    throws InvalidKeySpecException
227  {
228    return keyFacSpi.engineGeneratePublic(keySpec);
229  }
230
231  /**
232   * Generates a private key from the provided key specification.
233   * 
234   * @param keySpec
235   *          the key specification.
236   * @return the private key.
237   * @throws InvalidKeySpecException
238   *           if the key specification is invalid.
239   */
240  public final PrivateKey generatePrivate(KeySpec keySpec)
241    throws InvalidKeySpecException
242  {
243    return keyFacSpi.engineGeneratePrivate(keySpec);
244  }
245
246  /**
247   * Returns a key specification for the given key. <code>keySpec</code>
248   * identifies the specification class to return the key material in.
249   * 
250   * @param key
251   *          the key to use.
252   * @param keySpec
253   *          the specification class to use.
254   * @return the key specification in an instance of the requested specification
255   *         class.
256   * @throws InvalidKeySpecException
257   *           the requested key specification is inappropriate for this key or
258   *           the key is unrecognized.
259   */
260  public final <T extends KeySpec> T getKeySpec(Key key, Class<T> keySpec)
261    throws InvalidKeySpecException
262  {
263    return keyFacSpi.engineGetKeySpec(key, keySpec);
264  }
265
266  /**
267   * Translates the key from an unknown or untrusted provider into a key from
268   * this key factory.
269   * 
270   * @param key
271   *          the key to translate from.
272   * @return the translated key.
273   * @throws InvalidKeyException
274   *           if the key cannot be processed by this key factory.
275   */
276  public final Key translateKey(Key key) throws InvalidKeyException
277  {
278    return keyFacSpi.engineTranslateKey(key);
279  }
280}