Source for javax.crypto.KeyGenerator

   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: }