libjava/classpath/javax/crypto/KeyGenerator.java

   1 /* KeyGenerator.java -- Interface to a symmetric key generator.
   2    Copyright (C) 2004  Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package javax.crypto;
  40
  41 import gnu.java.security.Engine;
  42
  43 import java.lang.reflect.InvocationTargetException;
  44 import java.security.InvalidAlgorithmParameterException;
  45 import java.security.NoSuchAlgorithmException;
  46 import java.security.NoSuchProviderException;
  47 import java.security.Provider;
  48 import java.security.SecureRandom;
  49 import java.security.Security;
  50 import java.security.spec.AlgorithmParameterSpec;
  51
  52 /**
  53  * A generic producer of keys for symmetric cryptography. The keys
  54  * returned may be simple wrappers around byte arrays, or, if the
  55  * target cipher requires them, more complex objects.
  56  *
  57  * @author Casey Marshall (csm@gnu.org)
  58  * @since 1.4
  59  * @see Cipher
  60  * @see Mac
  61  */
  62 public class KeyGenerator
  63 {
  64
  65   // Constants and fields.
  66   // ------------------------------------------------------------------------
  67
  68   private static final String SERVICE = "KeyGenerator";
  69
  70   /** The underlying generator implementation. */
  71   private KeyGeneratorSpi kgSpi;
  72
  73   /** The provider of the implementation. */
  74   private Provider provider;
  75
  76   /** The name of the algorithm. */
  77   private String algorithm;
  78
  79   // Constructor.
  80   // ------------------------------------------------------------------------
  81
  82   /**
  83    * Create a new key generator.
  84    *
  85    * @param kgSpi     The underlying generator.
  86    * @param provider  The provider of this implementation.
  87    * @param algorithm The algorithm's name.
  88    */
  89   protected KeyGenerator(KeyGeneratorSpi kgSpi, Provider provider,
  90                          String algorithm)
  91   {
  92     this.kgSpi = kgSpi;
  93     this.provider = provider;
  94     this.algorithm = algorithm;
  95   }
  96
  97   /**
  98    * Create a new key generator, returning the first available implementation.
  99    *
 100    * @param algorithm The generator algorithm name.
 101    * @throws NoSuchAlgorithmException If the specified algorithm does not exist.
 102    * @throws IllegalArgumentException if <code>algorithm</code> is
 103    *           <code>null</code> or is an empty string.
 104    */
 105   public static final KeyGenerator getInstance(String algorithm)
 106       throws NoSuchAlgorithmException
 107   {
 108     Provider[] p = Security.getProviders();
 109     NoSuchAlgorithmException lastException = null;
 110     for (int i = 0; i < p.length; i++)
 111       try
 112         {
 113           return getInstance(algorithm, p[i]);
 114         }
 115       catch (NoSuchAlgorithmException x)
 116         {
 117           lastException = x;
 118         }
 119     if (lastException != null)
 120       throw lastException;
 121     throw new NoSuchAlgorithmException(algorithm);
 122   }
 123
 124   /**
 125    * Create a new key generator from the named provider.
 126    *
 127    * @param algorithm The generator algorithm name.
 128    * @param provider The name of the provider to use.
 129    * @return An appropriate key generator, if found.
 130    * @throws NoSuchAlgorithmException If the specified algorithm is not
 131    *           implemented by the named provider.
 132    * @throws NoSuchProviderException If the named provider does not exist.
 133    * @throws IllegalArgumentException if either <code>algorithm</code> or
 134    *           <code>provider</code> is <code>null</code>, or if
 135    *           <code>algorithm</code> is an empty string.
 136    */
 137   public static final KeyGenerator getInstance(String algorithm, String provider)
 138       throws NoSuchAlgorithmException, NoSuchProviderException
 139   {
 140     if (provider == null)
 141       throw new IllegalArgumentException("provider MUST NOT be null");
 142     Provider p = Security.getProvider(provider);
 143     if (p == null)
 144       throw new NoSuchProviderException(provider);
 145     return getInstance(algorithm, p);
 146   }
 147
 148   /**
 149    * Create a new key generator from the supplied provider.
 150    *
 151    * @param algorithm The generator algorithm name.
 152    * @param provider The provider to use.
 153    * @return An appropriate key generator, if found.
 154    * @throws NoSuchAlgorithmException If the specified algorithm is not
 155    *           implemented by the provider.
 156    * @throws IllegalArgumentException if either <code>algorithm</code> or
 157    *           <code>provider</code> is <code>null</code>, or if
 158    *           <code>algorithm</code> is an empty string.
 159    */
 160   public static final KeyGenerator getInstance(String algorithm,
 161                                                Provider provider)
 162       throws NoSuchAlgorithmException
 163   {
 164     StringBuilder sb = new StringBuilder("KeyGenerator algorithm [")
 165         .append(algorithm).append("] from provider[")
 166         .append(provider).append("] could not be created");
 167     Throwable cause;
 168     try
 169       {
 170         Object spi = Engine.getInstance(SERVICE, algorithm, provider);
 171         KeyGenerator instance = new KeyGenerator((KeyGeneratorSpi) spi,
 172                                                  provider,
 173                                                  algorithm);
 174         instance.init(new SecureRandom());
 175         return instance;
 176       }
 177     catch (InvocationTargetException x)
 178       {
 179         cause = x.getCause();
 180         if (cause instanceof NoSuchAlgorithmException)
 181           throw (NoSuchAlgorithmException) cause;
 182         if (cause == null)
 183           cause = x;
 184       }
 185     catch (ClassCastException x)
 186       {
 187         cause = x;
 188       }
 189     NoSuchAlgorithmException x = new NoSuchAlgorithmException(sb.toString());
 190     x.initCause(cause);
 191     throw x;
 192   }
 193
 194   /**
 195    * Generate a key.
 196    *
 197    * @return The new key.
 198    */
 199   public final SecretKey generateKey()
 200   {
 201     return kgSpi.engineGenerateKey();
 202   }
 203
 204   /**
 205    * Return the name of this key generator.
 206    *
 207    * @return The algorithm name.
 208    */
 209   public final String getAlgorithm()
 210   {
 211     return algorithm;
 212   }
 213
 214   /**
 215    * Return the provider of the underlying implementation.
 216    *
 217    * @return The provider.
 218    */
 219   public final Provider getProvider()
 220   {
 221     return provider;
 222   }
 223
 224   /**
 225    * Initialize this key generator with a set of parameters; the
 226    * highest-priority {@link java.security.SecureRandom} implementation
 227    * will be used.
 228    *
 229    * @param params The algorithm parameters.
 230    * @throws java.security.InvalidAlgorithmParameterException If the
 231    *         supplied parameters are inapproprate.
 232    */
 233   public final void init(AlgorithmParameterSpec params)
 234     throws InvalidAlgorithmParameterException
 235   {
 236     init(params, new SecureRandom());
 237   }
 238
 239   /**
 240    * Initialize this key generator with a set of parameters and a source
 241    * of randomness.
 242    *
 243    * @param params The algorithm parameters.
 244    * @param random The source of randomness.
 245    * @throws java.security.InvalidAlgorithmParameterException If the
 246    *         supplied parameters are inapproprate.
 247    */
 248   public final void init(AlgorithmParameterSpec params, SecureRandom random)
 249     throws InvalidAlgorithmParameterException
 250   {
 251     kgSpi.engineInit(params, random);
 252   }
 253
 254   /**
 255    * Initialize this key generator with a key size (in bits); the
 256    * highest-priority {@link java.security.SecureRandom} implementation
 257    * will be used.
 258    *
 259    * @param keySize The target key size, in bits.
 260    * @throws java.security.InvalidParameterException If the
 261    *         key size is unsupported.
 262    */
 263   public final void init(int keySize)
 264   {
 265     init(keySize, new SecureRandom());
 266   }
 267
 268   /**
 269    * Initialize this key generator with a key size (in bits) and a
 270    * source of randomness.
 271    *
 272    * @param keySize The target key size, in bits.
 273    * @param random  The source of randomness.
 274    * @throws java.security.InvalidAlgorithmParameterException If the
 275    *         key size is unsupported.
 276    */
 277   public final void init(int keySize, SecureRandom random)
 278   {
 279     kgSpi.engineInit(keySize, random);
 280   }
 281
 282   /**
 283    * Initialize this key generator with a source of randomness. The
 284    * implementation-specific default parameters (such as key size) will
 285    * be used.
 286    *
 287    * @param random The source of randomness.
 288    */
 289   public final void init(SecureRandom random)
 290   {
 291     kgSpi.engineInit(random);
 292   }
 293 }