option to privatize Public File URL

Currently if you make a file available to the public it gets assigned a URL from from the autoincrement database ID column. This allows people to download your entire public files database. It would be nice to have an alphanumeric representation for the public file URL such as:
http://yoursite.com/webfm_send/9YUHDGU2

instead of:
http://yoursite.com/webfm_send/3

Thanks,
Justin