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.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: }