What happens when you want to make sure that a certain node does not appear as a leaf, without having to resort to pruning?
You wouldn't want to use pruning because the original algorithm would uncover the sensitive leaf if fed with the original data set. So, as you don't know what algorithm your opponent will use, your best option is to "cook" the data, as little as possible.
You can find links to the paper by searching dblp with "kalles hiding" or "kalles hide".
(PENDING UPDATE) Here's an online prototype (admittedly, a bit esoteric in how to use it) ...
... and a further prototype on demonstrating a proof of concept based on diophantine equations ...