libjava/classpath/java/security/KeyFactory.java

   1 /* KeyFactory.java --- Key Factory Class
   2    Copyright (C) 1999, 2003, 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 java.security;
  40
  41 import gnu.java.lang.CPStringBuilder;
  42
  43 import gnu.java.security.Engine;
  44
  45 import java.lang.reflect.InvocationTargetException;
  46 import java.security.spec.InvalidKeySpecException;
  47 import java.security.spec.KeySpec;
  48
  49 /**
  50  * Key factories are used to convert keys (opaque cryptographic keys of type
  51  * {@link Key}) into key specifications (transparent representations of the
  52  * underlying key material).
  53  *
  54  * <p>Key factories are bi-directional. They allow a key class to be converted
  55  * into a key specification (key material) and back again. For example DSA
  56  * public keys can be specified as <code>DSAPublicKeySpec</code> or
  57  * <code>X509EncodedKeySpec</code>. A key factory translates these key
  58  * specifications.</p>
  59  *
  60  * @since 1.2
  61  * @see Key
  62  * @see KeySpec
  63  * @see java.security.spec.DSAPublicKeySpec
  64  * @see java.security.spec.X509EncodedKeySpec
  65    @author Mark Benvenuto
  66  */
  67 public class KeyFactory
  68 {
  69   /** The service name for key factories. */
  70   private static final String KEY_FACTORY = "KeyFactory";
  71
  72   private KeyFactorySpi keyFacSpi;
  73   private Provider provider;
  74   private String algorithm;
  75
  76   /**
  77    * Constructs a new instance of <code>KeyFactory</code> with the specified
  78    * parameters.
  79    *
  80    * @param keyFacSpi
  81    *          the key factory to use.
  82    * @param provider
  83    *          the provider to use.
  84    * @param algorithm
  85    *          the name of the key algorithm to use.
  86    */
  87   protected KeyFactory(KeyFactorySpi keyFacSpi, Provider provider,
  88                        String algorithm)
  89   {
  90     this.keyFacSpi = keyFacSpi;
  91     this.provider = provider;
  92     this.algorithm = algorithm;
  93   }
  94
  95   /**
  96    * Returns a new instance of <code>KeyFactory</code> representing the
  97    * specified key factory.
  98    *
  99    * @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 }