Intelligent Reflecting Surface-Assisted Wireless Secret Key Generation against Multiple Eavesdroppers.

Area of Science:

• Wireless communication security
• Information theory
• Metamaterials and intelligent surfaces

Background:

• Physical layer security is crucial for secure communication.
• Intelligent Reflecting Surfaces (IRS) offer a promising approach to manipulate wireless environments.
• Optimizing IRS for enhanced signal-to-noise ratio (SNR) and secure key generation remains a challenge.

Purpose of the Study:

• To propose an improved physical layer key generation scheme using IRS.
• To maximize secret key capacity by enhancing legitimate user SNR and degrading eavesdropper channels.
• To optimize IRS reflection coefficients for passive beamforming.

Main Methods:

• Deployment of IRS near the legitimate user in a MISO system.
• Optimization of the IRS reflection coefficient matrix.
• Derivation of the lower bound for achievable key capacity.
• Application of semi-definite relaxation (SDR) and convex-concave procedure (CCP) for optimization.

Main Results:

• The proposed scheme significantly improves secret key capacity compared to benchmark schemes.
• IRS passive beamforming effectively enhances the legitimate user's SNR.
• Simultaneous degradation of eavesdropper channel quality was achieved.
• Reduced hardware costs were observed with the proposed scheme.

Conclusions:

• The IRS-assisted physical layer key generation scheme effectively maximizes secret key capacity.
• The optimization strategy using SDR and CCP is efficient for IRS deployment.
• This approach offers a practical and cost-effective solution for enhanced wireless security.