libjava/java/security/KeyFactory.java

   1 /* KeyFactory.java --- Key Factory Class
   2    Copyright (C) 1999 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., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 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 package java.security;
  39 import java.security.spec.KeySpec;
  40 import java.security.spec.InvalidKeySpecException;
  41
  42 /**
  43    Key factories are used to convert keys (opaque cryptographic
  44    keys of type Key) into key specifications (transparent
  45    representations of the underlying key material).
  46
  47    Key factories are bi-directional. They allow a key class
  48    to be converted into a key specification (key material) and
  49    back again.
  50
  51    For example DSA public keys can be specified as
  52    DSAPublicKeySpec or X509EncodedKeySpec. The key factory
  53    translate these key specifications.
  54
  55    @since JDK 1.2
  56    @author Mark Benvenuto
  57  */
  58 public class KeyFactory
  59 {
  60   private KeyFactorySpi keyFacSpi;
  61   private Provider provider;
  62   private String algorithm;
  63
  64   /**
  65      Constructs a new keyFactory with the specified parameters.
  66
  67      @param keyFacSpi Key Factory SPI to use
  68      @param provider the provider of the Key Factory SPI
  69      @param algorithm the name of the key algorithm for this key factory
  70    */
  71   protected KeyFactory(KeyFactorySpi keyFacSpi, Provider provider,
  72                        String algorithm)
  73   {
  74     this.keyFacSpi = keyFacSpi;
  75     this.provider = provider;
  76     this.algorithm = algorithm;
  77   }
  78
  79   /**
  80      Gets an instance of the KeyFactory class representing
  81      the specified key factory. If the algorithm is not
  82      found then, it throws NoSuchAlgorithmException.
  83
  84      @param algorithm the name of algorithm to choose
  85      @return a KeyFactory repesenting the desired algorithm
  86
  87      @throws NoSuchAlgorithmException if the algorithm is not implemented by providers
  88    */
  89   public static KeyFactory getInstance(String algorithm)
  90     throws NoSuchAlgorithmException
  91   {
  92     Provider[] p = Security.getProviders();
  93
  94     for (int i = 0; i < p.length; i++)
  95       {
  96         String classname = p[i].getProperty("KeyFactory." + algorithm);
  97         if (classname != null)
  98           return getInstance(classname, algorithm, p[i]);
  99       }
 100
 101     throw new NoSuchAlgorithmException(algorithm);
 102   }
 103
 104   /**
 105      Gets an instance of the KeyFactory class representing
 106      the specified key factory from the specified provider.
 107      If the algorithm is not found then, it throws
 108      NoSuchAlgorithmException. If the provider is not found, then
 109      it throws NoSuchProviderException.
 110
 111      @param algorithm the name of algorithm to choose
 112      @param provider the name of the provider to find the algorithm in
 113      @return a KeyFactory repesenting the desired algorithm
 114
 115      @throws NoSuchAlgorithmException if the algorithm is not implemented by the provider
 116      @throws NoSuchProviderException if the provider is not found
 117    */
 118   public static KeyFactory getInstance(String algorithm, String provider)
 119     throws NoSuchAlgorithmException, NoSuchProviderException
 120   {
 121     Provider p = Security.getProvider(provider);
 122     if (p == null)
 123       throw new NoSuchProviderException();
 124
 125     return getInstance(p.getProperty("KeyFactory." + algorithm),
 126                        algorithm, p);
 127   }
 128
 129   private static KeyFactory getInstance(String classname,
 130                                         String algorithm,
 131                                         Provider provider)
 132     throws NoSuchAlgorithmException
 133   {
 134
 135     try
 136       {
 137         return new KeyFactory((KeyFactorySpi) Class.forName(classname).
 138                               newInstance(), provider, algorithm);
 139       }
 140     catch (ClassNotFoundException cnfe)
 141       {
 142         throw new NoSuchAlgorithmException("Class not found");
 143       }
 144     catch (InstantiationException ie)
 145       {
 146         throw new NoSuchAlgorithmException("Class instantiation failed");
 147       }
 148     catch (IllegalAccessException iae)
 149       {
 150         throw new NoSuchAlgorithmException("Illegal Access");
 151       }
 152   }
 153
 154   /**
 155      Gets the provider that the class is from.
 156
 157      @return the provider of this class
 158    */
 159   public final Provider getProvider()
 160   {
 161     return provider;
 162   }
 163
 164   /**
 165      Returns the name of the algorithm used
 166
 167      @return A string with the name of the algorithm
 168    */
 169   public final String getAlgorithm()
 170   {
 171     return algorithm;
 172   }
 173
 174   /**
 175      Generates a public key from the provided key specification.
 176
 177      @param keySpec key specification
 178
 179      @return the public key
 180
 181      @throws InvalidKeySpecException invalid key specification for
 182      this key factory to produce a public key
 183    */
 184   public final PublicKey generatePublic(KeySpec keySpec) throws
 185     InvalidKeySpecException
 186   {
 187     return keyFacSpi.engineGeneratePublic(keySpec);
 188   }
 189
 190   /**
 191      Generates a private key from the provided key specification.
 192
 193      @param keySpec key specification
 194
 195      @return the private key
 196
 197      @throws InvalidKeySpecException invalid key specification for
 198      this key factory to produce a private key
 199    */
 200   public final PrivateKey generatePrivate(KeySpec keySpec) throws
 201     InvalidKeySpecException
 202   {
 203     return keyFacSpi.engineGeneratePrivate(keySpec);
 204   }
 205
 206   /**
 207      Returns a key specification for the given key. keySpec
 208      identifies the specification class to return the key
 209      material in.
 210
 211      @param key the key
 212      @param keySpec the specification class to return the
 213      key material in.
 214
 215      @return the key specification in an instance of the requested
 216      specification class
 217
 218      @throws InvalidKeySpecException the requested key specification
 219      is inappropriate for this key or the key is
 220      unrecognized.
 221    */
 222   public final KeySpec getKeySpec(Key key, Class keySpec)
 223     throws InvalidKeySpecException
 224   {
 225     return keyFacSpi.engineGetKeySpec(key, keySpec);
 226   }
 227
 228   /**
 229      Translates the key from an unknown or untrusted provider
 230      into a key for this key factory.
 231
 232      @param the key from an unknown or untrusted provider
 233
 234      @return the translated key
 235
 236      @throws InvalidKeySpecException if the key cannot be
 237      processed by this key factory
 238    */
 239   public final Key translateKey(Key key) throws InvalidKeyException
 240   {
 241     return keyFacSpi.engineTranslateKey(key);
 242   }
 243 }