I can't really answer your question, as I haven't used this routine. I would sincerely doubt it has back doors however. It is a GPLed piece of software which makes that very unlikely.
I have used "TrueCrypt" however, and have found it to be quite nice and feature-full, as well as having an excellent reputation. It is also GPLed and is cross platform.
EDIT: Personally, I would never even consider touching a piece of encryption software that wasn't open source and peer reviewed. That is your best protection from that sort of thing, in my opinion.
Insanity: Doing the same thing over and over and each time expecting a different result.
Democracy is 2 wolves and a lamb voting on the menu. Liberty is an armed lamb protesting the electoral outcome. A Republic negates the need for an armed protest.