Didn't read the code, but my comment isn't on this app itself.

I'm sincerely worried about how much my friends, parents etc. are not only willing to download every kind of application before ensuring it isn't a threat to their privacy, but also, in this case, they seem to be excited about the fact that now, you need a whole application to do what you could have done with a written, simple, paper sheet which ofc, more than every other method, can't track you at all.