package gnu.crypto.jce.prng;  // -*- mode: java; c-basic-offset: 3 -*-

// ----------------------------------------------------------------------------
// $Id: CSPRNGSpi.java,v 1.2 2005/10/06 04:24:15 rsdio Exp $
//
// Copyright (C) 2004 Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// GNU Crypto is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; see the file COPYING.  If not, write to the
//
//    Free Software Foundation Inc.,
//    51 Franklin Street, Fifth Floor,
//    Boston, MA 02110-1301
//    USA
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give
// you permission to link this library with independent modules to
// produce an executable, regardless of the license terms of these
// independent modules, and to copy and distribute the resulting
// executable under terms of your choice, provided that you also meet,
// for each linked independent module, the terms and conditions of the
// license of that module.  An independent module is a module which is
// not derived from or based on this library.  If you modify this
// library, you may extend this exception to your version of the
// library, but you are not obligated to do so.  If you do not wish to
// do so, delete this exception statement from your version.
// ----------------------------------------------------------------------------

import gnu.crypto.Registry;
import gnu.crypto.prng.CSPRNG;
import gnu.crypto.prng.IRandom;
import gnu.crypto.prng.LimitReachedException;

import java.net.MalformedURLException;
import java.security.SecureRandomSpi;

/**
 * The implementation of the continuously-seeded SecureRandom
 * <i>Service Provider Interface</i> (<b>SPI</b>) adapter.<p>
 *
 * @version $Revision: 1.2 $
 */
public class CSPRNGSpi extends SecureRandomSpi {

   // Constants and variables
   // -------------------------------------------------------------------------

   private final IRandom adaptee;

   // Constructor(s)
   // -------------------------------------------------------------------------

   public CSPRNGSpi()
   throws ClassNotFoundException, MalformedURLException, NumberFormatException {
      super();

      adaptee = CSPRNG.getSystemInstance();
   }

   // Instance methods
   // -------------------------------------------------------------------------

   protected byte[] engineGenerateSeed(final int count) {
      if (count < 0) {
         throw new IllegalArgumentException("count must be nonnegative");
      }
      byte[] buf = new byte[count];
      if (count == 0) {
         return buf;
      }
      engineNextBytes(buf);
      return buf;
   }

   protected void engineNextBytes(final byte[] buffer) {
      if (buffer == null) {
         throw new NullPointerException();
      }
      try {
         adaptee.nextBytes(buffer, 0, buffer.length);
      } catch (LimitReachedException lre) {
         throw new RuntimeException("random-number generator has been exhausted");
      }
   }

   protected void engineSetSeed(final byte[] seed) {
      if (seed == null) {
         throw new NullPointerException();
      }
      adaptee.addRandomBytes(seed, 0, seed.length);
   }
}