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.lang.CPStringBuilder;
042    
043    import gnu.java.security.Engine;
044    
045    import java.io.IOException;
046    import java.lang.reflect.InvocationTargetException;
047    import java.security.spec.AlgorithmParameterSpec;
048    import java.security.spec.InvalidParameterSpecException;
049    
050    /**
051     * <code>AlgorithmParameters</code> is an Algorithm Parameters class which
052     * provides an interface through which the user can manage the parameters of an
053     * Algorithm.
054     *
055     * @author Mark Benvenuto
056     * @since 1.2
057     * @see AlgorithmParameterSpec
058     * @see java.security.spec.DSAParameterSpec
059     * @see KeyPairGenerator
060     */
061    public class AlgorithmParameters
062    {
063      /** Service name for algorithm parameters. */
064      private static final String ALGORITHM_PARAMETERS = "AlgorithmParameters";
065    
066      private AlgorithmParametersSpi paramSpi;
067      private Provider provider;
068      private String algorithm;
069    
070      /**
071       * Constructs a new instance of <code>AlgorithmParameters</code>.
072       *
073       * @param paramSpi
074       *          the engine to use.
075       * @param provider
076       *          the provider to use.
077       * @param algorithm
078       *          the algorithm to use.
079       */
080      protected AlgorithmParameters(AlgorithmParametersSpi paramSpi,
081                                    Provider provider, String algorithm)
082      {
083        this.paramSpi = paramSpi;
084        this.provider = provider;
085        this.algorithm = algorithm;
086      }
087    
088      /** @return A string with the name of the algorithm used. */
089      public final String getAlgorithm()
090      {
091        return algorithm;
092      }
093    
094      /**
095       * Returns a new instance of <code>AlgorithmParameters</code> representing
096       * the specified algorithm parameters.
097       * <p>
098       * The returned <code>AlgorithmParameters</code> must still be initialized
099       * with an <code>init()</code> method.
100       *
101       * @param algorithm the algorithm to use.
102       * @return the new instance repesenting the desired algorithm.
103       * @throws NoSuchAlgorithmException if the algorithm is not implemented by any
104       *           provider.
105       * @throws IllegalArgumentException if <code>algorithm</code> is
106       *           <code>null</code> or is an empty string.
107       */
108      public static AlgorithmParameters getInstance(String algorithm)
109          throws NoSuchAlgorithmException
110      {
111        Provider[] p = Security.getProviders();
112        NoSuchAlgorithmException lastException = null;
113        for (int i = 0; i < p.length; i++)
114          try
115            {
116              return getInstance(algorithm, p[i]);
117            }
118          catch (NoSuchAlgorithmException x)
119            {
120              lastException = x;
121            }
122        if (lastException != null)
123          throw lastException;
124        throw new NoSuchAlgorithmException(algorithm);
125      }
126    
127      /**
128       * Returns a new instance of <code>AlgorithmParameters</code> representing
129       * the specified algorithm parameters from a named provider.
130       * <p>
131       * The returned <code>AlgorithmParameters</code> must still be intialized
132       * with an <code>init()</code> method.
133       * </p>
134       *
135       * @param algorithm the algorithm to use.
136       * @param provider the name of the {@link Provider} to use.
137       * @return the new instance repesenting the desired algorithm.
138       * @throws NoSuchAlgorithmException if the algorithm is not implemented by the
139       *           named provider.
140       * @throws NoSuchProviderException if the named provider was not found.
141       * @throws IllegalArgumentException if either <code>algorithm</code> or
142       *           <code>provider</code> is <code>null</code> or empty.
143       */
144      public static AlgorithmParameters getInstance(String algorithm,
145                                                    String provider)
146          throws NoSuchAlgorithmException, NoSuchProviderException
147      {
148        if (provider == null)
149          throw new IllegalArgumentException("provider MUST NOT be null");
150        provider = provider.trim();
151        if (provider.length() == 0)
152          throw new IllegalArgumentException("provider MUST NOT be empty");
153        Provider p = Security.getProvider(provider);
154        if (p == null)
155          throw new NoSuchProviderException(provider);
156        return getInstance(algorithm, p);
157      }
158    
159      /**
160       * Returns a new instance of <code>AlgorithmParameters</code> representing
161       * the specified algorithm parameters from the specified {@link Provider}.
162       * <p>
163       * The returned <code>AlgorithmParameters</code> must still be intialized
164       * with an <code>init()</code> method.
165       *
166       * @param algorithm the algorithm to use.
167       * @param provider the {@link Provider} to use.
168       * @return the new instance repesenting the desired algorithm.
169       * @throws NoSuchAlgorithmException if the algorithm is not implemented by the
170       *           {@link Provider}.
171       * @throws IllegalArgumentException if either <code>algorithm</code> or
172       *           <code>provider</code> is <code>null</code>, or if
173       *           <code>algorithm</code> is an empty string.
174       * @since 1.4
175       */
176      public static AlgorithmParameters getInstance(String algorithm,
177                                                    Provider provider)
178          throws NoSuchAlgorithmException
179      {
180        CPStringBuilder sb = new CPStringBuilder("AlgorithmParameters for algorithm [")
181            .append(algorithm).append("] from provider[")
182            .append(provider).append("] could not be created");
183        Throwable cause;
184        try
185          {
186            Object spi = Engine.getInstance(ALGORITHM_PARAMETERS, algorithm, provider);
187            return new AlgorithmParameters((AlgorithmParametersSpi) spi,
188                                           provider,
189                                           algorithm);
190          }
191        catch (InvocationTargetException x)
192          {
193            cause = x.getCause();
194            if (cause instanceof NoSuchAlgorithmException)
195              throw (NoSuchAlgorithmException) cause;
196            if (cause == null)
197              cause = x;
198          }
199        catch (ClassCastException x)
200          {
201            cause = x;
202          }
203        NoSuchAlgorithmException x = new NoSuchAlgorithmException(sb.toString());
204        x.initCause(cause);
205        throw x;
206      }
207    
208      /** @return the provider of this parameter object. */
209      public final Provider getProvider()
210      {
211        return provider;
212      }
213    
214      /**
215       * Initializes the engine with the specified {@link AlgorithmParameterSpec}.
216       *
217       * @param paramSpec
218       *          A {@link AlgorithmParameterSpec} to use.
219       * @throws InvalidParameterSpecException
220       *           if <code>paramSpec</code> is invalid.
221       */
222      public final void init(AlgorithmParameterSpec paramSpec)
223        throws InvalidParameterSpecException
224      {
225        paramSpi.engineInit(paramSpec);
226      }
227    
228      /**
229       * Initializes the engine with the specified parameters stored in the byte
230       * array and decodes them according to the ASN.1 specification. If the ASN.1
231       * specification exists then it succeeds otherwise an {@link IOException} is
232       * thrown.
233       *
234       * @param params
235       *          the parameters to use.
236       * @throws IOException
237       *           if a decoding error occurs.
238       */
239      public final void init(byte[]params) throws IOException
240      {
241        paramSpi.engineInit(params);
242      }
243    
244      /**
245       * Initializes the engine with the specified parameters stored in the byte
246       * array and decodes them according to the specified decoding specification.
247       * If <code>format</code> is <code>null</code>, then this method decodes the
248       * byte array using the ASN.1 specification if it exists, otherwise it throws
249       * an {@link IOException}.
250       *
251       * @param params
252       *          the parameters to use.
253       * @param format
254       *          the name of decoding format to use.
255       * @throws IOException
256       *           if a decoding error occurs.
257       */
258      public final void init(byte[]params, String format) throws IOException
259      {
260        paramSpi.engineInit(params, format);
261      }
262    
263      /**
264       * Returns a new instance of <code>AlgorithmParameters</code> as a
265       * designated parameter specification {@link Class}.
266       *
267       * @param paramSpec
268       *          the {@link Class} to use.
269       * @return the parameter specification.
270       * @throws InvalidParameterSpecException
271       *           if <code>paramSpec</code> is invalid.
272       */
273      public final <T extends AlgorithmParameterSpec>
274      T getParameterSpec(Class<T> paramSpec)
275        throws InvalidParameterSpecException
276      {
277        return paramSpi.engineGetParameterSpec(paramSpec);
278      }
279    
280      /**
281       * Returns the parameters in the default encoding format. The primary encoding
282       * format is ASN.1 if it exists for the specified type.
283       *
284       * @return byte array representing the parameters.
285       */
286      public final byte[] getEncoded() throws IOException
287      {
288        return paramSpi.engineGetEncoded();
289      }
290    
291      /**
292       * Returns the parameters in the specified encoding format. If
293       * <code>format</code> is <code>null</code> then the ASN.1 encoding
294       * format is used if it exists for the specified type.
295       *
296       * @param format
297       *          the name of the encoding format to use.
298       * @return the parameters encoded using the specified encoding scheme.
299       * @throws IOException
300       *           if an encoding exception occurs, or if this parameter object has
301       *           not been initialized.
302       */
303      public final byte[] getEncoded(String format) throws IOException
304      {
305        return paramSpi.engineGetEncoded(format);
306      }
307    
308      /**
309       * Returns a string representation of the encoded form.
310       *
311       * @return a string representation of the encoded form.
312       */
313      public final String toString()
314      {
315        return paramSpi.engineToString();
316      }
317    }