001/* AlgorithmParameterGenerator.java --- Algorithm Parameter Generator
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.AlgorithmParameterSpec;
047
048/**
049 * <code>AlgorithmParameterGenerator</code> is used to generate algorithm
050 * parameters for specified algorithms.
051 *
052 * <p>In case the client does not explicitly initialize the
053 * <code>AlgorithmParameterGenerator</code> (via a call to an
054 * <code>init()</code> method), each provider must supply (and document) a
055 * default initialization. For example, the <b>GNU</b> provider uses a default
056 * modulus prime size of <code>1024</code> bits for the generation of <i>DSA</i>
057 * parameters.
058 *
059 * @author Mark Benvenuto
060 * @since 1.2
061 * @see AlgorithmParameters
062 * @see AlgorithmParameterSpec
063 */
064public class AlgorithmParameterGenerator
065{
066  /** Service name for algorithm parameter generators. */
067  private static final String ALGORITHM_PARAMETER_GENERATOR =
068    "AlgorithmParameterGenerator";
069
070  private AlgorithmParameterGeneratorSpi paramGenSpi;
071  private Provider provider;
072  private String algorithm;
073
074  /**
075   * Constructs a new instance of <code>AlgorithmParameterGenerator</code>.
076   *
077   * @param paramGenSpi
078   *          the generator to use.
079   * @param provider
080   *          the provider to use.
081   * @param algorithm
082   *          the algorithm to use.
083   */
084  protected AlgorithmParameterGenerator(AlgorithmParameterGeneratorSpi
085                                        paramGenSpi, Provider provider,
086                                        String algorithm)
087  {
088    this.paramGenSpi = paramGenSpi;
089    this.provider = provider;
090    this.algorithm = algorithm;
091  }
092
093  /** @return the name of the algorithm. */
094  public final String getAlgorithm()
095  {
096    return algorithm;
097  }
098
099  /**
100   * Returns a new <code>AlgorithmParameterGenerator</code> instance which
101   * generates algorithm parameters for the specified algorithm.
102   *
103   * @param algorithm the name of algorithm to use.
104   * @return the new instance.
105   * @throws NoSuchAlgorithmException if <code>algorithm</code> is not
106   *           implemented by any provider.
107   * @throws IllegalArgumentException if <code>algorithm</code> is
108   *           <code>null</code> or is an empty string.
109   */
110  public static AlgorithmParameterGenerator getInstance(String algorithm)
111      throws NoSuchAlgorithmException
112  {
113    Provider[] p = Security.getProviders();
114    NoSuchAlgorithmException lastException = null;
115    for (int i = 0; i < p.length; i++)
116      try
117        {
118          return getInstance(algorithm, p[i]);
119        }
120      catch (NoSuchAlgorithmException x)
121        {
122          lastException = x;
123        }
124    if (lastException != null)
125      throw lastException;
126    throw new NoSuchAlgorithmException(algorithm);
127  }
128
129  /**
130   * Returns a new <code>AlgorithmParameterGenerator</code> instance which
131   * generates algorithm parameters for the specified algorithm.
132   *
133   * @param algorithm the name of algorithm to use.
134   * @param provider the name of the {@link Provider} to use.
135   * @return the new instance.
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 AlgorithmParameterGenerator 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 <code>AlgorithmParameterGenerator</code> instance which
159   * generates algorithm parameters for the specified algorithm.
160   *
161   * @param algorithm the name of algorithm to use.
162   * @param provider the {@link Provider} to use.
163   * @return the new instance.
164   * @throws NoSuchAlgorithmException if the algorithm is not implemented by
165   *           {@link Provider}.
166   * @throws IllegalArgumentException if either <code>algorithm</code> or
167   *           <code>provider</code> is <code>null</code>, or if
168   *           <code>algorithm</code> is an empty string.
169   * @since 1.4
170   * @see Provider
171   */
172  public static AlgorithmParameterGenerator getInstance(String algorithm,
173                                                        Provider provider)
174      throws NoSuchAlgorithmException
175  {
176    CPStringBuilder sb = new CPStringBuilder()
177        .append("AlgorithmParameterGenerator for algorithm [")
178        .append(algorithm).append("] from provider[")
179        .append(provider).append("] could not be created");
180    Throwable cause;
181    try
182      {
183        Object spi = Engine.getInstance(ALGORITHM_PARAMETER_GENERATOR,
184                                        algorithm,
185                                        provider);
186        return new AlgorithmParameterGenerator((AlgorithmParameterGeneratorSpi) spi,
187                                               provider,
188                                               algorithm);
189      }
190    catch (InvocationTargetException x)
191      {
192        cause = x.getCause();
193        if (cause instanceof NoSuchAlgorithmException)
194          throw (NoSuchAlgorithmException) cause;
195        if (cause == null)
196          cause = x;
197      }
198    catch (ClassCastException x)
199      {
200        cause = x;
201      }
202    NoSuchAlgorithmException x = new NoSuchAlgorithmException(sb.toString());
203    x.initCause(cause);
204    throw x;
205  }
206
207  /** @return the {@link Provider} of this generator. */
208  public final Provider getProvider()
209  {
210    return provider;
211  }
212
213  /**
214   * Initializes this instance with the specified size. Since no source of
215   * randomness is supplied, a default one will be used.
216   *
217   * @param size
218   *          size (in bits) to use.
219   */
220  public final void init(int size)
221  {
222    init(size, new SecureRandom());
223  }
224
225  /**
226   * Initializes this instance with the specified key-size and source of
227   * randomness.
228   *
229   * @param size
230   *          the size (in bits) to use.
231   * @param random
232   *          the {@link SecureRandom} to use.
233   */
234  public final void init(int size, SecureRandom random)
235  {
236    paramGenSpi.engineInit(size, random);
237  }
238
239  /**
240   * Initializes this instance with the specified {@link AlgorithmParameterSpec}.
241   * Since no source of randomness is supplied, a default one will be used.
242   *
243   * @param genParamSpec
244   *          the {@link AlgorithmParameterSpec} to use.
245   * @throws InvalidAlgorithmParameterException
246   *           if <code>genParamSpec</code> is invalid.
247   */
248  public final void init(AlgorithmParameterSpec genParamSpec)
249      throws InvalidAlgorithmParameterException
250  {
251    init(genParamSpec, new SecureRandom());
252  }
253
254  /**
255   * Initializes this instance with the specified {@link AlgorithmParameterSpec}
256   * and source of randomness.
257   *
258   * @param genParamSpec
259   *          the {@link AlgorithmParameterSpec} to use.
260   * @param random
261   *          the {@link SecureRandom} to use.
262   * @throws InvalidAlgorithmParameterException
263   *           if <code>genParamSpec</code> is invalid.
264   */
265  public final void init(AlgorithmParameterSpec genParamSpec,
266                         SecureRandom random)
267    throws InvalidAlgorithmParameterException
268  {
269    paramGenSpi.engineInit(genParamSpec, random);
270  }
271
272  /** @return a new instance of {@link AlgorithmParameters}. */
273  public final AlgorithmParameters generateParameters()
274  {
275    return paramGenSpi.engineGenerateParameters();
276  }
277}