In this work, an explicit scheme of wiretap coding based on polar lattices is proposed to achieve the secrecy capacity of the additive white Gaussian noise (AWGN) wiretap channel. Firstly, polar lattices are used to construct secrecy-good lattices for the mod-Λs Gaussian wiretap channel. Then we propose an explicit shaping scheme to remove this mod-Λs front end and extend polar lattices to the genuine Gaussian wiretap channel. The shaping technique is based on the lattice Gaussian distribution, which leads to a binary asymmetric channel at each level for the multilevel lattice codes. By employing the asymmetric polar coding technique, we construct an AWGN-good lattice and a secrecy-good lattice with optimal shaping simultaneously. As a result, the encoding complexity for the sender and the decoding complexity for the legitimate receiver are both O(N log N log(log N )). The proposed scheme is proven to be semantically secure.In simple terms, the secrecy capacity is defined as the maximum achievable rate under both the reliability and strong secrecy conditions. When W and V are both symmetric, and W is degraded with respect to V , the secrecy capacity is given by C(V ) − C(W ) [3], where C(·) denotes the channel capacity. DRAFT Polar codes [7] have shown their great potential in solving the wiretap coding problem. The polar coding scheme proposed in [8], combined with the block Markov coding technique [9], was proved to achieve the strong secrecy capacity when W and V are both binary-input symmetric channels, and W is degraded with respect to V . More recently, polar wiretap coding has been extended to general wiretap channels (not necessarily degraded or symmetric) in [10] and [11]. For continuous channels such as the GWC, there also has been notable progress in wiretap lattice coding. On the theoretical aspect, the existence of lattice codes achieving the secrecy capacity to within 1 2 nat under the strong secrecy as well as semantic security criterion was demonstrated in [6]. On the practical aspect, wiretap lattice codes were proposed in [12] and [13] to maximize the eavesdropper's decoding error probability. June 13, 2018 DRAFT 3 A. Our contribution Polar lattices, the counterpart of polar codes in the Euclidean space, have already been proved to be additive white Gaussian noise (AWGN)-good [14] and further to achieve the AWGN channel capacity with lattice Gaussian shaping [15] 1 . Motivated by [8], we will propose polar lattices to achieve both strong secrecy and reliability over the mod-Λ s GWC. Conceptually, this polar lattice structure can be regarded as a secrecy-good lattice Λ e nested within an AWGN-good lattice Λ b (Λ e ⊂ Λ b ). Further, we will propose a Gaussian shaping scheme over Λ b and Λ e , using the multilevel asymmetric polar coding technique. As a result, we will accomplish the design of an explicit lattice coding scheme which achieves the secrecy capacity of the GWC with semantic security.• The first technical contribution of this paper is the explicit construction of secrecy-good polar latt...