  We assume a dark $U_{D}$ symmetric hidden sector and explore its possible
content such that neutrino mass and Dark Matter are generated through the
scotogenic mechanism. The hidden sector is considered analogue to the Standard
Model, namely the charge assignment of hidden fermions is chiral and
anomaly-free. Moreover, $U_{D}$ is assumed broken by an only Higgs singlet that
also generates masses to all hidden fermions, therefore the charge assignment
is subjected to additional restriction. We search by computer program for
charge assignments satisfying all these conditions, and identify the resulting
minimal scotogenic models for Majorana neutrinos and Dirac neutrinos
respectively in the sense of minimal number of messenger scalar involved.
Particle spectrum, couplings, and phenomenologies of these minimal models are
briefly discussed. DM is found multicomponent and always contains Dirac
fermionic species.
