On the dual of generalized Boolean bent functions over ℤ4

We introduce and study dual functions of generalized Boolean bent functions over ℤ₄, i.e., functions from F₂-vector spaces to ℤ₄ whose Fourier transforms have constant magnitudes. For a special class of generalized Boolean bent functions with even number of variables constructed from a class of quadratic binary bent functions in polynomial forms proposed by the first author, we explicitly determine their dual functions by explicitly determining duals of these binary bent functions.