Normal Extensions of Bent Functions
Claude Carlet, Hans Dobbertin, Gregor Leander · IEEE Transactions on Information Theory · 2004
In this paper, the notion of normal extension is introduced for bent functions, i.e., maximally nonlinear Boolean functions. We apply this concept to characterize when the direct sum of bent functions is normal, and we prove that the direct sum of a normal bent function and a nonnormal bent function is always nonnormal.