nginx secure_link rails

gistfile1.nginxconf

# Downloads server
server {
  listen       80;
  server_name  files.domain.com;

  root /some/path/files.domain;

  location /downloads {
    secure_link $arg_md5,$arg_expires;
    secure_link_md5 "$secure_link_expires$uri DOWNLOAD_SECRET";

    if ($secure_link = "") {
        return 403;
    }

    if ($secure_link = "0") {
        return 410;
    }
  }
}