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

   1: /* CSPRNGSpi.java --
   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.prng;
  40: 
  41: import gnu.java.security.prng.IRandom;
  42: import gnu.java.security.prng.LimitReachedException;
  43: import gnu.java.security.jce.prng.SecureRandomAdapter;
  44: import gnu.javax.crypto.prng.CSPRNG;
  45: 
  46: import java.net.MalformedURLException;
  47: import java.security.SecureRandomSpi;
  48: 
  49: /**
  50:  * The implementation of the continuously-seeded SecureRandom <i>Service
  51:  * Provider Interface</i> (<b>SPI</b>) adapter.
  52:  */
  53: public class CSPRNGSpi
  54:     extends SecureRandomSpi
  55: {
  56:   private final IRandom adaptee;
  57:   private boolean virgin = true;
  58: 
  59:   public CSPRNGSpi() throws ClassNotFoundException, MalformedURLException,
  60:       NumberFormatException
  61:   {
  62:     super();
  63: 
  64:     adaptee = CSPRNG.getSystemInstance();
  65:   }
  66: 
  67:   protected byte[] engineGenerateSeed(final int numBytes)
  68:   {
  69:     return SecureRandomAdapter.getSeed(numBytes);
  70:   }
  71: 
  72:   protected void engineNextBytes(final byte[] buffer)
  73:   {
  74:     if (buffer == null)
  75:       throw new NullPointerException();
  76:     if (virgin)
  77:       {
  78:         engineSetSeed(engineGenerateSeed(32));
  79:       }
  80:     try
  81:       {
  82:         adaptee.nextBytes(buffer, 0, buffer.length);
  83:       }
  84:     catch (LimitReachedException lre)
  85:       {
  86:         throw new RuntimeException("random-number generator has been exhausted");
  87:       }
  88:   }
  89: 
  90:   protected void engineSetSeed(final byte[] seed)
  91:   {
  92:     if (seed == null)
  93:       throw new NullPointerException();
  94:     adaptee.addRandomBytes(seed, 0, seed.length);
  95:     virgin = false;
  96:   }
  97: }