  Neural Networks (NNs) are today used for all our daily tasks; for instance,
in mobile phones. We here want to show how to restrict their access to
privileged users. Our solution relies on a degraded implementation which can be
corrected thanks to a PIN. We explain how to select a few parameters in an NN
so as to maximize the gap in the accuracy between the premium and the degraded
modes. We report experiments on an implementation of our proposal on a deep NN
to prove its practicability.
