Source for java.security.KeyFactory

   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.security.Engine;
  42: 
  43: import java.lang.reflect.InvocationTargetException;
  44: import java.security.spec.InvalidKeySpecException;
  45: import java.security.spec.KeySpec;
  46: 
  47: /**
  48:  * Key factories are used to convert keys (opaque cryptographic keys of type
  49:  * {@link Key}) into key specifications (transparent representations of the
  50:  * underlying key material).
  51:  * 
  52:  * <p>Key factories are bi-directional. They allow a key class to be converted
  53:  * into a key specification (key material) and back again. For example DSA
  54:  * public keys can be specified as <code>DSAPublicKeySpec</code> or
  55:  * <code>X509EncodedKeySpec</code>. A key factory translates these key
  56:  * specifications.</p>
  57:  *
  58:  * @since 1.2
  59:  * @see Key
  60:  * @see KeySpec
  61:  * @see java.security.spec.DSAPublicKeySpec
  62:  * @see java.security.spec.X509EncodedKeySpec
  63:    @author Mark Benvenuto
  64:  */
  65: public class KeyFactory
  66: {
  67:   /** The service name for key factories. */
  68:   private static final String KEY_FACTORY = "KeyFactory";
  69: 
  70:   private KeyFactorySpi keyFacSpi;
  71:   private Provider provider;
  72:   private String algorithm;
  73: 
  74:   /**
  75:    * Constructs a new instance of <code>KeyFactory</code> with the specified
  76:    * parameters.
  77:    * 
  78:    * @param keyFacSpi
  79:    *          the key factory to use.
  80:    * @param provider
  81:    *          the provider to use.
  82:    * @param algorithm
  83:    *          the name of the key algorithm to use.
  84:    */
  85:   protected KeyFactory(KeyFactorySpi keyFacSpi, Provider provider,
  86:                String algorithm)
  87:   {
  88:     this.keyFacSpi = keyFacSpi;
  89:     this.provider = provider;
  90:     this.algorithm = algorithm;
  91:   }
  92: 
  93:   /**
  94:    * Returns a new instance of <code>KeyFactory</code> representing the
  95:    * specified key factory.
  96:    * 
  97:    * @param algorithm the name of algorithm to use.
  98:    * @return a new instance repesenting the desired algorithm.
  99:    * @throws NoSuchAlgorithmException if the algorithm is not implemented by any
 100:    *           provider.
 101:    * @throws IllegalArgumentException if <code>algorithm</code> is
 102:    *           <code>null</code> or is an empty string.
 103:    */
 104:   public static KeyFactory getInstance(String algorithm)
 105:       throws NoSuchAlgorithmException
 106:   {
 107:     Provider[] p = Security.getProviders();
 108:     NoSuchAlgorithmException lastException = null;
 109:     for (int i = 0; i < p.length; i++)
 110:       try
 111:         {
 112:           return getInstance(algorithm, p[i]);
 113:         }
 114:       catch (NoSuchAlgorithmException x)
 115:         {
 116:           lastException = x;
 117:         }
 118:     if (lastException != null)
 119:       throw lastException;
 120:     throw new NoSuchAlgorithmException(algorithm);
 121:   }
 122: 
 123:   /**
 124:    * Returns a new instance of <code>KeyFactory</code> representing the
 125:    * specified key factory from the specified provider.
 126:    * 
 127:    * @param algorithm the name of algorithm to use.
 128:    * @param provider the name of the provider to use.
 129:    * @return a new instance repesenting the desired algorithm.
 130:    * @throws NoSuchAlgorithmException if the algorithm is not implemented by the
 131:    *           named provider.
 132:    * @throws NoSuchProviderException if the named provider was not found.
 133:    * @throws IllegalArgumentException if either <code>algorithm</code> or
 134:    *           <code>provider</code> is <code>null</code> or empty.
 135:    */
 136:   public static KeyFactory getInstance(String algorithm, String provider)
 137:       throws NoSuchAlgorithmException, NoSuchProviderException
 138:   {
 139:     if (provider == null)
 140:       throw new IllegalArgumentException("provider MUST NOT be null");
 141:     provider = provider.trim();
 142:     if (provider.length() == 0)
 143:       throw new IllegalArgumentException("provider MUST NOT be empty");
 144:     Provider p = Security.getProvider(provider);
 145:     if (p == null)
 146:       throw new NoSuchProviderException(provider);
 147:     return getInstance(algorithm, p);
 148:   }
 149: 
 150:   /**
 151:    * Returns a new instance of <code>KeyFactory</code> representing the
 152:    * specified key factory from the designated {@link Provider}.
 153:    * 
 154:    * @param algorithm the name of algorithm to use.
 155:    * @param provider the {@link Provider} to use.
 156:    * @return a new instance repesenting the desired algorithm.
 157:    * @throws NoSuchAlgorithmException if the algorithm is not implemented by
 158:    *           {@link Provider}.
 159:    * @throws IllegalArgumentException if either <code>algorithm</code> or
 160:    *           <code>provider</code> is <code>null</code>, or if
 161:    *           <code>algorithm</code> is an empty string.
 162:    * @since 1.4
 163:    * @see Provider
 164:    */
 165:   public static KeyFactory getInstance(String algorithm, Provider provider)
 166:       throws NoSuchAlgorithmException
 167:   {
 168:     StringBuilder sb = new StringBuilder("KeyFactory for algorithm [")
 169:         .append(algorithm).append("] from provider[")
 170:         .append(provider).append("] could not be created");
 171:     Throwable cause;
 172:     try
 173:       {
 174:         Object spi = Engine.getInstance(KEY_FACTORY, algorithm, provider);
 175:         return new KeyFactory((KeyFactorySpi) spi, provider, algorithm);
 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:    * Returns the {@link Provider} of this instance.
 196:    * 
 197:    * @return the {@link Provider} of this instance.
 198:    */
 199:   public final Provider getProvider()
 200:   {
 201:     return provider;
 202:   }
 203: 
 204:   /**
 205:    * Returns the name of the algorithm used.
 206:    * 
 207:    * @return the name of the algorithm used.
 208:    */
 209:   public final String getAlgorithm()
 210:   {
 211:     return algorithm;
 212:   }
 213: 
 214:   /**
 215:    * Generates a public key from the provided key specification.
 216:    * 
 217:    * @param keySpec
 218:    *          the key specification.
 219:    * @return the public key.
 220:    * @throws InvalidKeySpecException
 221:    *           if the key specification is invalid.
 222:    */
 223:   public final PublicKey generatePublic(KeySpec keySpec)
 224:     throws InvalidKeySpecException
 225:   {
 226:     return keyFacSpi.engineGeneratePublic(keySpec);
 227:   }
 228: 
 229:   /**
 230:    * Generates a private key from the provided key specification.
 231:    * 
 232:    * @param keySpec
 233:    *          the key specification.
 234:    * @return the private key.
 235:    * @throws InvalidKeySpecException
 236:    *           if the key specification is invalid.
 237:    */
 238:   public final PrivateKey generatePrivate(KeySpec keySpec)
 239:     throws InvalidKeySpecException
 240:   {
 241:     return keyFacSpi.engineGeneratePrivate(keySpec);
 242:   }
 243: 
 244:   /**
 245:    * Returns a key specification for the given key. <code>keySpec</code>
 246:    * identifies the specification class to return the key material in.
 247:    * 
 248:    * @param key
 249:    *          the key to use.
 250:    * @param keySpec
 251:    *          the specification class to use.
 252:    * @return the key specification in an instance of the requested specification
 253:    *         class.
 254:    * @throws InvalidKeySpecException
 255:    *           the requested key specification is inappropriate for this key or
 256:    *           the key is unrecognized.
 257:    */
 258:   public final <T extends KeySpec> T getKeySpec(Key key, Class<T> keySpec)
 259:     throws InvalidKeySpecException
 260:   {
 261:     return keyFacSpi.engineGetKeySpec(key, keySpec);
 262:   }
 263: 
 264:   /**
 265:    * Translates the key from an unknown or untrusted provider into a key from
 266:    * this key factory.
 267:    * 
 268:    * @param key
 269:    *          the key to translate from.
 270:    * @return the translated key.
 271:    * @throws InvalidKeyException
 272:    *           if the key cannot be processed by this key factory.
 273:    */
 274:   public final Key translateKey(Key key) throws InvalidKeyException
 275:   {
 276:     return keyFacSpi.engineTranslateKey(key);
 277:   }
 278: }