protected static function mcrypt_dev_urandom_exists() { if (!isset(self::$mcrypt_dev_urandom_exists)) { self::$mcrypt_dev_urandom_exists = function_exists('mcrypt_create_iv') && (version_compare(PHP_VERSION, '5.3.7') >= 0 || !self::is_windows()); } return self::$mcrypt_dev_urandom_exists; }