/*
 * Copyright 2017 Graz University of Technology EAAF-Core Components has been developed in a
 * cooperation between EGIZ, A-SIT Plus, A-SIT, and Graz University of Technology.
 *
 * Licensed under the EUPL, Version 1.2 or - as soon they will be approved by the European
 * Commission - subsequent versions of the EUPL (the "Licence"); You may not use this work except in
 * compliance with the Licence. You may obtain a copy of the Licence at:
 * https://joinup.ec.europa.eu/news/understanding-eupl-v12
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the Licence
 * is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the Licence for the specific language governing permissions and limitations under
 * the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text file for details on the
 * various modules and licenses. The "NOTICE" text file is part of the distribution. Any derivative
 * works that you distribute must include a readable copy of the "NOTICE" text file.
*/

package at.gv.egiz.eaaf.core.impl.idp.process.support;

import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

/**
 * Holder for a secure random instance following the initialization on demand holder design pattern.
 * The secure random instance is a singleton that is initialized on first usage.
 *
 * @author tknall
 *
 */
public class SecureRandomHolder {

  private SecureRandomHolder() {

  }

  private static final SecureRandom SRND_INSTANCE;

  static {
    try {
      SRND_INSTANCE = SecureRandom.getInstance("SHA1PRNG");
    } catch (final NoSuchAlgorithmException e) {
      throw new RuntimeException("Unable to instantiate SHA1PRNG.", e);
    }
  }

  /**
   * Returns a secure random generator instance.
   *
   * @return The secure random instance.
   */
  public static SecureRandom getInstance() {
    return SecureRandomHolder.SRND_INSTANCE;
  }

}