Encryption in phase space for classical coherent optical communications.

Area of Science:

• Optical communication networks
• Physical layer security
• Information theory

Background:

• Optical fiber communication networks are vulnerable to physical layer attacks.
• Existing security measures often fail to address optical layer threats.
• Data encryption at the physical layer is crucial for network security.

Purpose of the Study:

• To theoretically analyze the security of a random phase mask encryption system.
• To determine optimal operating conditions for secure data transmission.
• To evaluate the effectiveness of encryption against eavesdropping.

Main Methods:

• Mutual information analysis for theoretical security assessment.
• Numerical simulations for optimizing operating conditions (4-PSK, 16-PSK, 128-QAM).
• Experimental demonstration using 16-QAM modulation.

Main Results:

• Identified secure operating conditions for multiple modulation formats.
• Experimental validation confirmed the theoretical security predictions.
• Encryption efficacy was verified against tapping attacks.

Conclusions:

• Random phase mask encryption provides robust physical layer security for optical networks.
• System security is maintained when the attacker lacks knowledge of the phase modulator and pre-shared key.
• The proposed method offers a practical solution for enhancing optical communication security.