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The core random number generators

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package prng.seeds;

import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.prefs.Preferences;
import prng.SecureRandomProvider;

/**
 * Store seed data in the JVM's system preferences storage. Note that accessing system preferences often requires administrator privileges.
 *
 * @author Simon Greatrix
 */
public class SystemPrefsStorage extends PreferenceStorage {

  /**
   * Create storage that used the system preferences.
   *
   * @throws StorageException if the system preferences cannot be accessed
   */
  public SystemPrefsStorage() throws StorageException {
    // no-op
  }


  @Override
  protected Preferences getPreferences() throws StorageException {
    try {
      return AccessController.doPrivileged(
          (PrivilegedAction) () -> Preferences.systemNodeForPackage(
              SeedStorage.class));
    } catch (SecurityException e) {
      SecureRandomProvider.LOG.warn(
          "Lacking permission \"RuntimePermission preferences\" or access to system preferences - cannot access seed data in system preferences");
      throw new StorageException(
          "Privilege 'preferences' is required to use preferences",
          e);
    }
  }
}