/*
 * Copyright (c) 2002-2018 ymnk, JCraft,Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this list of conditions
 * and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided with
 * the distribution.
 *
 * 3. The names of the authors may not be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL JCRAFT, INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.jcraft.jsch.jce;

import java.security.SecureRandom;

public class Random implements com.jcraft.jsch.Random {
  private byte[] tmp = new byte[16];
  private SecureRandom random = null;

  public Random() {

    // We hope that 'new SecureRandom()' will use NativePRNG algorithm
    // on Sun's Java5 for GNU/Linux and Solaris.
    // It seems NativePRNG refers to /dev/urandom and it must not be blocked,
    // but NativePRNG is slower than SHA1PRNG ;-<
    // TIPS: By adding option '-Djava.security.egd=file:/dev/./urandom'
    //       SHA1PRNG will be used instead of NativePRNG.
    // On MacOSX, 'new SecureRandom()' will use NativePRNG algorithm and
    // it is also slower than SHA1PRNG.
    // On Windows, 'new SecureRandom()' will use SHA1PRNG algorithm.
    random = new SecureRandom();

    /*
    try {
      random = SecureRandom.getInstance("SHA1PRNG");
      return;
    } catch (NoSuchAlgorithmException e) {
      // System.err.println(e);
    }

    // The following code is for IBM's JCE
    try {
      random = SecureRandom.getInstance("IBMSecureRandom");
      return;
    } catch (NoSuchAlgorithmException ee) {
      // System.err.println(ee);
    }
    */
  }

  @Override
  public void fill(byte[] foo, int start, int len) {
    /*
    // This case will not become true in our usage.
    if (start == 0 && foo.length == len) {
      random.nextBytes(foo);
      return;
    }
    */
    if (len > tmp.length) {
      tmp = new byte[len];
    }
    random.nextBytes(tmp);
    System.arraycopy(tmp, 0, foo, start, len);
  }
}
