Security-enhanced ultra-high-order QAM quantum noise stream cipher assisted by intensity and phase chaotic encryption

An ultra-high-order QAM quantum noise stream cipher (QNSC) scheme assisted by intensity and phase chaotic encryption is proposed. In this scheme, the legal transmitter (Alice) first encrypts the original low-order QAM signal into an ultra-high-order QAM signal according to the pre-shared seed key based on the Y-00 protocol, and then conceals the intensity and phase information of the ultra-high-order QAM signal through the intensity and phase chaos generated from a nonlinear delay chaotic source for enhancing the security. The intensity and phase chaotic carrier can be eliminated by the open-loop chaotic synchronization module at the legal receiver (Bob). The scheme was numerically verified in 112 Gbit/s (28 GBaud 16QAM plaintext) and 168 Gbit/s (28 GBaud 64QAM plaintext) 65536QAM/QNSC systems, which can achieve 600 km and 150 km transmission at 7% HD-FEC threshold, and 1000 km and 350 km transmission at 20% SD-FEC threshold, respectively. Meanwhile, the number of masked signals (NMS) and the detection failure probability (DFP) in the scheme are obviously higher than in the original QAM/QNSC system. We believe that the proposed scheme is a promising strategy for enhancing the security of QAM/QNSC transmission systems.