You have two options
1. Use 323's built in FTP server. Just create a share and assign rights and you are good to go. Just FTP either manually, or cron it from another server.
2. Install fun_plug to run lighthttp. You can expose your files via HTTP this way. I'm not sure if lighthttp supports authentication, but if it does than you do it securely.
http://wiki.dns323.info/howto:ffp#lighttpd_web_server