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