Secrecy gain of Gaussian wiretap codes from 2- and 3-modular lattices

Lattice coding over a Gaussian wiretap channel is considered with respect to a lattice invariant called the secrecy gain, which was introduced in [1] to characterize the confusion that a chosen lattice can cause at the eavesdropper: the higher the secrecy gain of the lattice, the more confusion. In this paper, secrecy gains of several 2- and 3-modular lattices are computed. Most are shown to have a secrecy gain larger than the best unimodular lattices can achieve.