Source for gnu.javax.crypto.jce.key.SecretKeyGeneratorImpl

   1: /* SecretKeyGeneratorImpl.java -- symmetric key pair generator.
   2:    Copyright (C) 2004, 2006  Free Software Foundation, Inc.
   3: 
   4: This file is a 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 of the License, or (at
   9: your option) 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; if not, write to the Free Software
  18: Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
  19: 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 gnu.javax.crypto.jce.key;
  40: 
  41: import gnu.javax.crypto.cipher.CipherFactory;
  42: import gnu.javax.crypto.cipher.IBlockCipher;
  43: 
  44: import java.security.InvalidAlgorithmParameterException;
  45: import java.security.InvalidParameterException;
  46: import java.security.SecureRandom;
  47: import java.security.spec.AlgorithmParameterSpec;
  48: 
  49: import java.util.Iterator;
  50: import java.util.LinkedList;
  51: import java.util.List;
  52: 
  53: import javax.crypto.KeyGeneratorSpi;
  54: import javax.crypto.SecretKey;
  55: import javax.crypto.spec.SecretKeySpec;
  56: 
  57: public class SecretKeyGeneratorImpl
  58:     extends KeyGeneratorSpi
  59: {
  60:   protected final int defaultKeySize;
  61:   protected final List keySizes;
  62:   protected final String algorithm;
  63:   protected boolean init;
  64:   protected int currentKeySize;
  65:   protected SecureRandom random;
  66: 
  67:   protected SecretKeyGeneratorImpl(final String algorithm)
  68:   {
  69:     this.algorithm = algorithm;
  70:     IBlockCipher cipher = CipherFactory.getInstance(algorithm);
  71:     if (cipher == null)
  72:       throw new IllegalArgumentException("no such cipher: " + algorithm);
  73:     defaultKeySize = cipher.defaultKeySize();
  74:     keySizes = new LinkedList();
  75:     for (Iterator it = cipher.keySizes(); it.hasNext();)
  76:       keySizes.add(it.next());
  77:     init = false;
  78:   }
  79: 
  80:   protected SecretKey engineGenerateKey()
  81:   {
  82:     if (! init)
  83:       throw new IllegalStateException("not initialized");
  84:     byte[] buf = new byte[currentKeySize];
  85:     random.nextBytes(buf);
  86:     return new SecretKeySpec(buf, algorithm);
  87:   }
  88: 
  89:   protected void engineInit(AlgorithmParameterSpec params, SecureRandom random)
  90:       throws InvalidAlgorithmParameterException
  91:   {
  92:     throw new InvalidAlgorithmParameterException(
  93:         algorithm + " does not support algorithm paramaters");
  94:   }
  95: 
  96:   protected void engineInit(int keySize, SecureRandom random)
  97:   {
  98:     keySize >>>= 3; // Use bytes.
  99:     if (! keySizes.contains(Integer.valueOf(keySize)))
 100:       throw new InvalidParameterException("unsupported key size: " + keySize
 101:                                           + ", valid sizes are: " + keySizes);
 102:     currentKeySize = keySize;
 103:     this.random = random;
 104:     init = true;
 105:   }
 106: 
 107:   protected void engineInit(SecureRandom random)
 108:   {
 109:     engineInit(defaultKeySize << 3, random);
 110:   }
 111: }