Physical layer security for CO-OFDM based on chaotic real-imaginary component shuffling and dynamic Latin square...

Area of Science:

• Optical Communications
• Physical Layer Security
• Cryptography

Background:

• Coherent Optical Orthogonal Frequency-Division Multiplexing (CO-OFDM) systems are crucial for high-capacity optical networks.
• Enhancing physical layer security in these systems is vital to prevent unauthorized access and data interception.
• Existing security measures may introduce performance penalties or lack sufficient complexity.

Purpose of the Study:

• To propose a hierarchical complex symbol encryption scheme for CO-OFDM systems.
• To enhance physical layer security without compromising system performance.
• To provide a robust and efficient encryption solution for next-generation optical communications.

Main Methods:

• A hierarchical encryption scheme utilizing a 6-D chaotic system after Quadrature Amplitude Modulation (QAM) mapping.
• Two scrambling layers: intra-block scrambling using 3D Hilbert curves and inter-block scrambling with dynamic Latin squares.
• Chaotic keys drive permutations and dynamic phase rotation for complex symbol manipulation.

Main Results:

• The proposed scheme introduces no Bit Error Rate (BER) penalty and reduces Peak-to-Average Power Ratio (PAPR) by approximately 0.5 dB.
• Simulations over 240 km of standard single-mode fiber (SSMF) demonstrate effective security against eavesdropping.
• Authorized users achieve near-baseline BER, while eavesdroppers face a BER close to 0.5, irrespective of Signal-to-Noise Ratio (SNR).

Conclusions:

• The encryption scheme offers a key space exceeding 10^101, ensuring high security.
• The method is highly secure and efficient, suitable for next-generation coherent optical communications.
• It effectively enhances physical layer security in CO-OFDM systems without performance degradation.