A Novel Scrambler Design for Enhancing Secrecy Transmission Based On Polar Code

Scrambling is a way of enhancing physical layer security presented in many papers. However, few of these papers have mentioned the scrambling effect on the polar coding secrecy. In this letter, we introduce a new scrambling module combined with a polar coding system, in which pre-assigned key is unnecessary. The presented scrambling module combines linear and nonlinear structure. The presented linear structure increases the branch number in a low-complexity way to enhance algorithm diffusion power, and the nonlinear part can resist the differential attack and reduces the mutual information between its input and output. With the proposed module, the bit channels, which are good for Bob and Eve, can also be applied to transmit secret message, making transmission rate of the secret massage configurable. Simulation results show that our method can guarantee the secrecy transmission between Alice and Bob.