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

   1: /* ARCFourRandomSpi.java --
   2:    Copyright (C) 2002, 2003, 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.Registry;
  42: 
  43: import gnu.java.security.jce.prng.SecureRandomAdapter;
  44: 
  45: import gnu.java.security.prng.IRandom;
  46: import gnu.java.security.prng.LimitReachedException;
  47: 
  48: import gnu.javax.crypto.prng.ARCFour;
  49: import gnu.javax.crypto.prng.PRNGFactory;
  50: 
  51: import java.security.SecureRandomSpi;
  52: 
  53: import java.util.HashMap;
  54: 
  55: /**
  56:  * Implementation of the <i>Service Provider Interface</i> (<b>SPI</b>) for
  57:  * the ARCFOUR keystream generator.
  58:  */
  59: public class ARCFourRandomSpi
  60:     extends SecureRandomSpi
  61: {
  62:   /** Our underlying prng instance. */
  63:   private IRandom adaptee;
  64:   /** Have we been initialized? */
  65:   private boolean virgin;
  66: 
  67:   /**
  68:    * Default 0-arguments constructor.
  69:    */
  70:   public ARCFourRandomSpi()
  71:   {
  72:     super();
  73:     adaptee = PRNGFactory.getInstance(Registry.ARCFOUR_PRNG);
  74:     virgin = true;
  75:   }
  76: 
  77:   public byte[] engineGenerateSeed(int numBytes)
  78:   {
  79:     return SecureRandomAdapter.getSeed(numBytes);
  80:   }
  81: 
  82:   public void engineNextBytes(byte[] bytes)
  83:   {
  84:     if (virgin)
  85:       this.engineSetSeed(engineGenerateSeed(32));
  86:     try
  87:       {
  88:         adaptee.nextBytes(bytes, 0, bytes.length);
  89:       }
  90:     catch (LimitReachedException ignored)
  91:       {
  92:       }
  93:   }
  94: 
  95:   public void engineSetSeed(byte[] seed)
  96:   {
  97:     HashMap attributes = new HashMap();
  98:     attributes.put(ARCFour.ARCFOUR_KEY_MATERIAL, seed);
  99:     adaptee.init(attributes);
 100:     virgin = false;
 101:   }
 102: }