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While reconfigurable intelligent surface (RIS) technology shows great promise for wireless communication, an adversary using such technology can threaten wireless performance. This paper explores an RIS-based attack on time-division duplex (TDD) based wireless systems that use channel reciprocity for physical layer key generation (PLKG). We demonstrate that deploying a non-reciprocal RIS with a non-symmetric "beyond diagonal" (BD) phase shift matrix can compromise channel reciprocity and thus break key consistency. The attack can be achieved without transmission of signal energy, channel state information (CSI), and synchronization with the legitimate system, and thus it is difficult to detect and counteract. We propose a physically consistent BD-RIS model and verify the impact of its attack on the secret key rate (SKR) of the legitimate system via simulations. Moreover, we provide a heuristic approach for optimizing the BD-RIS configuration to realize a more severe attack in cases where some partial knowledge of the channel state information is available. Our results demonstrate that such channel reciprocity attacks can significantly decrease the SKR of the legitimate system.
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This content will become publicly available on June 8, 2026
Beyond Diagonal RIS Aided Power Minimization Beamforming for MIMO Systems
Beyond diagonal reconfigurable intelligent surfaces (BD-RIS) with interconnected reflecting elements present an emerging technology for manipulating the propagation environment, and their new structure requires careful investigation. In this paper, we explore BD-RIS-aided power minimization beamforming, where the BD-RIS scattering matrix and transmit beamforming are jointly optimized under nonconvex constraints related to signal-to-interference-plus-noise ratio (SINR) thresholds and the structure of the scattering matrix. To efficiently solve the problem, we propose a single-loop algorithm, where we adopt a variable splitting strategy with an auxiliary variable to split the scattering matrix, and then alternately update the resulting variables. Through further derivations, we show that each nonconvex subproblem can be solved efficiently. Simulation results demonstrate the high efficiency of our proposed single loop algorithm and the effectiveness of BD-RIS in improving performance.
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- PAR ID:
- 10638601
- Publisher / Repository:
- IEEE
- Date Published:
- Page Range / eLocation ID:
- 1821 to 1826
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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