A policy of opposition to enlightenment or the spread of knowledge WordNet 3.0 & Open English WordNet

In the fields of philosophy, the terms obscurantism and obscurationism identify and describe the anti-intellectual practices of deliberately presenting information in an abstruse and imprecise manner that limits further inquiry and understanding of a subject. Wikipedia

Aiming to hide information or insight Wikidata

Deliberate obscurity or vagueness. Wiktionary