I have been reviewing a number of applications for securing deleting files. I understand the concepts of overwriting the file several times with zeros and random characters; however, I don't understand the concept of renaming the file up to thirty times before actually deleting the file.
Actually I do not have a direct answer to your question but you do not have to overwrite the data nor the FS-entry 30 times.
The german magazine for computer technics (c't) has published an article about a paper which handles this topic. The quintessence of the article is that overwriting the data once is enough.
The c't article (german): http://www.heise.de/newsticker/meldung/Sicheres-Loeschen-Einmal-ueberschreiben-genuegt-198816.html
Information about the paper (english): Link
After all it should suffice to rename the file to /tmp/tmp_file (or so) and overwrite it with random data or zeros before deleting it.