1. A computer implemented method for classifying securely a private query sample using exact k-nn classification, comprising the steps of: applying a secure dot product protocol to the private query sample and a plurality of private labeled samples to determine securely distances between the private query sample and the plurality of private labeled samples; applying a secure k-rank protocol to the distances to determine a nearest distance of a k th nearest labeled sample having a particular label; and applying a secure Parzen window protocol using the nearest distance to label the private query sample according to the particular label.