How I can management private files
For bypass Drupal permission, you can implements hook_file_download():

/**
 * Implements hook_file_download().
 */
function mymodule_file_download($uri) {
  if (someCondition()) {
    if (!user_access('some permissions')) {
      // Access to the file is denied.
      return -1;
    }
    else {
      return array('Content-Type' =&gt; file_get_mimetype($uri));
    }
  }
}