001    /* AlgorithmParameters.java --- Algorithm Parameters Implementation Class
002       Copyright (C) 1999, 2003, 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 java.security;
040    
041    import gnu.java.security.Engine;
042    
043    import java.io.IOException;
044    import java.lang.reflect.InvocationTargetException;
045    import java.security.spec.AlgorithmParameterSpec;
046    import java.security.spec.InvalidParameterSpecException;
047    
048    /**
049     * <code>AlgorithmParameters</code> is an Algorithm Parameters class which
050     * provides an interface through which the user can manage the parameters of an
051     * Algorithm.
052     *
053     * @author Mark Benvenuto
054     * @since 1.2
055     * @see AlgorithmParameterSpec
056     * @see java.security.spec.DSAParameterSpec
057     * @see KeyPairGenerator
058     */
059    public class AlgorithmParameters
060    {
061      /** Service name for algorithm parameters. */
062      private static final String ALGORITHM_PARAMETERS = "AlgorithmParameters";
063    
064      private AlgorithmParametersSpi paramSpi;
065      private Provider provider;
066      private String algorithm;
067    
068      /**
069       * Constructs a new instance of <code>AlgorithmParameters</code>.
070       * 
071       * @param paramSpi
072       *          the engine to use.
073       * @param provider
074       *          the provider to use.
075       * @param algorithm
076       *          the algorithm to use.
077       */
078      protected AlgorithmParameters(AlgorithmParametersSpi paramSpi,
079                                    Provider provider, String algorithm)
080      {
081        this.paramSpi = paramSpi;
082        this.provider = provider;
083        this.algorithm = algorithm;
084      }
085    
086      /** @return A string with the name of the algorithm used. */
087      public final String getAlgorithm()
088      {
089        return algorithm;
090      }
091    
092      /**
093       * Returns a new instance of <code>AlgorithmParameters</code> representing
094       * the specified algorithm parameters.
095       * <p>
096       * The returned <code>AlgorithmParameters</code> must still be initialized
097       * with an <code>init()</code> method.
098       * 
099       * @param algorithm the algorithm to use.
100       * @return the 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 AlgorithmParameters 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>AlgorithmParameters</code> representing
127       * the specified algorithm parameters from a named provider.
128       * <p>
129       * The returned <code>AlgorithmParameters</code> must still be intialized
130       * with an <code>init()</code> method.
131       * </p>
132       * 
133       * @param algorithm the algorithm to use.
134       * @param provider the name of the {@link Provider} to use.
135       * @return the new instance repesenting the desired algorithm.
136       * @throws NoSuchAlgorithmException if the algorithm is not implemented by the
137       *           named provider.
138       * @throws NoSuchProviderException if the named provider was not found.
139       * @throws IllegalArgumentException if either <code>algorithm</code> or
140       *           <code>provider</code> is <code>null</code> or empty.
141       */
142      public static AlgorithmParameters getInstance(String algorithm,
143                                                    String provider)
144          throws NoSuchAlgorithmException, NoSuchProviderException
145      {
146        if (provider == null)
147          throw new IllegalArgumentException("provider MUST NOT be null");
148        provider = provider.trim();
149        if (provider.length() == 0)
150          throw new IllegalArgumentException("provider MUST NOT be empty");
151        Provider p = Security.getProvider(provider);
152        if (p == null)
153          throw new NoSuchProviderException(provider);
154        return getInstance(algorithm, p);
155      }
156    
157      /**
158       * Returns a new instance of <code>AlgorithmParameters</code> representing
159       * the specified algorithm parameters from the specified {@link Provider}.
160       * <p>
161       * The returned <code>AlgorithmParameters</code> must still be intialized
162       * with an <code>init()</code> method.
163       * 
164       * @param algorithm the algorithm to use.
165       * @param provider the {@link Provider} to use.
166       * @return the new instance repesenting the desired algorithm.
167       * @throws NoSuchAlgorithmException if the algorithm is not implemented by the
168       *           {@link Provider}.
169       * @throws IllegalArgumentException if either <code>algorithm</code> or
170       *           <code>provider</code> is <code>null</code>, or if
171       *           <code>algorithm</code> is an empty string.
172       * @since 1.4
173       */
174      public static AlgorithmParameters getInstance(String algorithm,
175                                                    Provider provider)
176          throws NoSuchAlgorithmException
177      {
178        StringBuilder sb = new StringBuilder("AlgorithmParameters for algorithm [")
179            .append(algorithm).append("] from provider[")
180            .append(provider).append("] could not be created");
181        Throwable cause;
182        try
183          {
184            Object spi = Engine.getInstance(ALGORITHM_PARAMETERS, algorithm, provider);
185            return new AlgorithmParameters((AlgorithmParametersSpi) spi,
186                                           provider,
187                                           algorithm);
188          }
189        catch (InvocationTargetException x)
190          {
191            cause = x.getCause();
192            if (cause instanceof NoSuchAlgorithmException)
193              throw (NoSuchAlgorithmException) cause;
194            if (cause == null)
195              cause = x;
196          }
197        catch (ClassCastException x)
198          {
199            cause = x;
200          }
201        NoSuchAlgorithmException x = new NoSuchAlgorithmException(sb.toString());
202        x.initCause(cause);
203        throw x;
204      }
205    
206      /** @return the provider of this parameter object. */
207      public final Provider getProvider()
208      {
209        return provider;
210      }
211    
212      /**
213       * Initializes the engine with the specified {@link AlgorithmParameterSpec}.
214       * 
215       * @param paramSpec
216       *          A {@link AlgorithmParameterSpec} to use.
217       * @throws InvalidParameterSpecException
218       *           if <code>paramSpec</code> is invalid.
219       */
220      public final void init(AlgorithmParameterSpec paramSpec)
221        throws InvalidParameterSpecException
222      {
223        paramSpi.engineInit(paramSpec);
224      }
225    
226      /**
227       * Initializes the engine with the specified parameters stored in the byte
228       * array and decodes them according to the ASN.1 specification. If the ASN.1
229       * specification exists then it succeeds otherwise an {@link IOException} is
230       * thrown.
231       * 
232       * @param params
233       *          the parameters to use.
234       * @throws IOException
235       *           if a decoding error occurs.
236       */
237      public final void init(byte[]params) throws IOException
238      {
239        paramSpi.engineInit(params);
240      }
241    
242      /**
243       * Initializes the engine with the specified parameters stored in the byte
244       * array and decodes them according to the specified decoding specification.
245       * If <code>format</code> is <code>null</code>, then this method decodes the
246       * byte array using the ASN.1 specification if it exists, otherwise it throws
247       * an {@link IOException}.
248       * 
249       * @param params
250       *          the parameters to use.
251       * @param format
252       *          the name of decoding format to use.
253       * @throws IOException
254       *           if a decoding error occurs.
255       */
256      public final void init(byte[]params, String format) throws IOException
257      {
258        paramSpi.engineInit(params, format);
259      }
260    
261      /**
262       * Returns a new instance of <code>AlgorithmParameters</code> as a
263       * designated parameter specification {@link Class}.
264       * 
265       * @param paramSpec
266       *          the {@link Class} to use.
267       * @return the parameter specification.
268       * @throws InvalidParameterSpecException
269       *           if <code>paramSpec</code> is invalid.
270       */
271      public final <T extends AlgorithmParameterSpec>
272      T getParameterSpec(Class<T> paramSpec)
273        throws InvalidParameterSpecException
274      {
275        return paramSpi.engineGetParameterSpec(paramSpec);
276      }
277    
278      /**
279       * Returns the parameters in the default encoding format. The primary encoding
280       * format is ASN.1 if it exists for the specified type.
281       * 
282       * @return byte array representing the parameters.
283       */
284      public final byte[] getEncoded() throws IOException
285      {
286        return paramSpi.engineGetEncoded();
287      }
288    
289      /**
290       * Returns the parameters in the specified encoding format. If
291       * <code>format</code> is <code>null</code> then the ASN.1 encoding
292       * format is used if it exists for the specified type.
293       * 
294       * @param format
295       *          the name of the encoding format to use.
296       * @return the parameters encoded using the specified encoding scheme.
297       * @throws IOException
298       *           if an encoding exception occurs, or if this parameter object has
299       *           not been initialized.
300       */
301      public final byte[] getEncoded(String format) throws IOException
302      {
303        return paramSpi.engineGetEncoded(format);
304      }
305    
306      /**
307       * Returns a string representation of the encoded form.
308       * 
309       * @return a string representation of the encoded form.
310       */
311      public final String toString()
312      {
313        return paramSpi.engineToString();
314      }
315    }