Photonic-assisted microwave quantum-noise randomized cipher generation for signal security of wireless communications

Security enhancement is a major challenge in future 6G wireless networks. In this study, we have introduced a symmetric-key encryption system, which utilizes multilevel signaling, for the security of microwave signals against wireless interception. The system achieves quantum-noise signal masking at microwave frequencies via optical-tomicrowave frequency conversion based on the homodyne process, thus providing high signal security. We show experimental demonstrations of quantum-noise randomized phase-shift keying modulation/quadrature amplitude modulation cipher generation at a frequency of ~GHz via the intensity modulation/direct detection analog intermediate frequency over fiber transmission. The proposed system simultaneously achieves microwave signal delivery over a fiber link and signal encryption based on sufficient quantum-noise signal masking for wireless communication systems.