Source for gnu.javax.crypto.jce.prng.FortunaImpl

   1: /* FortunaImpl.java -- Fortuna SecureRandom adapter.
   2:    Copyright (C) 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.prng;
  40: 
  41: import gnu.java.security.prng.LimitReachedException;
  42: 
  43: import gnu.java.security.jce.prng.SecureRandomAdapter;
  44: 
  45: import gnu.javax.crypto.prng.Fortuna;
  46: 
  47: import java.security.SecureRandomSpi;
  48: import java.util.Collections;
  49: 
  50: public final class FortunaImpl
  51:     extends SecureRandomSpi
  52: {
  53:   private boolean virgin = true;
  54:   private final Fortuna adaptee;
  55: 
  56:   public FortunaImpl()
  57:   {
  58:     adaptee = new Fortuna();
  59:   }
  60: 
  61:   protected void engineSetSeed(byte[] seed)
  62:   {
  63:     synchronized (adaptee)
  64:       {
  65:         if (virgin)
  66:           {
  67:             adaptee.init (Collections.singletonMap (Fortuna.SEED, seed));
  68:             virgin = false;
  69:           }
  70:         else
  71:           {
  72:             adaptee.addRandomBytes (seed);
  73:           }
  74:       }
  75:   }
  76: 
  77:   protected void engineNextBytes(byte[] buffer)
  78:   {
  79:     synchronized (adaptee)
  80:       {
  81:         if (virgin)
  82:           {
  83:             this.engineSetSeed(engineGenerateSeed(32));
  84:           }
  85:         try
  86:           {
  87:             adaptee.nextBytes(buffer);
  88:           }
  89:         catch (LimitReachedException shouldNotHappen)
  90:           {
  91:             throw new Error(shouldNotHappen);
  92:           }
  93:       }
  94:   }
  95: 
  96:   protected byte[] engineGenerateSeed(int numBytes)
  97:   {
  98:     return SecureRandomAdapter.getSeed(numBytes);
  99:   }
 100: }