A novel chaos-based encryption approach for future-generation passive optical networks using SHA-2

A physical layer enhanced secure future generation passive optical network (PON) based on chaotic signal scrambling and the secure hash algorithm (SHA) is proposed and demonstrated. In this paper, the architecture of a wavelength-division multiplexed orthogonal frequency division multiplexing (OFDM) PON system based on a centralized light source using direct detection is analyzed. A logistic chaos map is employed here for the scrambling of OFDM symbols in the frequency and time domains. Before transmitting the signal over optical fiber, a message- digest of scrambled and descrambled OFDM signals is computed and compared at the optical line terminal and optical network unit, respectively, to verify the actual data recovered. For the downstream channel, a 10 Gbps 32 quadrature amplitude modulation OFDM signal is successfully transmitted over a distance of 50 km single-mode fiber within the limits of the peak-to-average-power value. The results show that the proposed scheme can protect the system from bad actors and eavesdroppers, while chaos encryption with SHA-2 provides a robust and promising secure strategy for future-generation PON systems.