IEEE Transactions on Information Forensics and Security

RIS-Assisted Integrated Communication and Secret Key Generation in Quasi-Static Environments

Zheyuan Deng, Xiaoyan Hu, Keming Ma, Liang Jin, Boming Li, QU Jing-hua

Published Jan 1, 2026• 0 citations

Abstract

Wireless Channel-based Secret Key Generation (WC-SKG) offers a promising alternative for wireless communication security, yet suffers from an extremely low key generation rate (KGR) in quasi-static environments (e.g., indoor Internet of Things), where key refresh cycles can extend for hours, creating a security vulnerability. Reconfigurable Intelligent Surfaces (RIS) can boost KGR by introducing artificial randomness, yet existing schemes only randomize the RIS phase shifts without using environmental priors, failing to maximize the KGR and meet the communication signal-to-noise ratio (SNR) requirement, causing service outages. To overcome these limitations, we propose the RIS-assisted Integrated Communication and WC-SKG (RICK) scheme. First, we treat the RIS-adjusted channel as a designable random variable and derive its optimal probability density function (PDF) using a novel geometric-algebraic framework to maximize the KGR under the communication SNR constraint. Second, we design a constrained-clustering-based quantization region division scheme tailored to this optimal non-uniform PDF, guaranteeing uniformly distributed secret keys. Simulation results show RICK achieves a KGR approximately 3.5-5 times higher than the state-of-the-art scheme while saving at least 20 dB of transmit power for the same KGR, confirming its effectiveness in quasi-static scenarios.

DOI: 10.1109/tifs.2026.3654398

Related papers

Reconfigurable-Intelligent-Surface-Assisted Secret Key Generation Under Spatially Correlated Channels in Quasi-Static Environments

Vahid Shahiri, Hamid Behroozi, Ali Kuhestani +1 more

Physical-layer key generation (PLKG) can significantly enhance the security of classic encryption schemes by efficiently providing secret keys in resource-limited network like the Internet of Things (IoT). However, reaching a high key generation rate (KGR) is challenging in applications like smart home or remote area sensing with quasi-static channels. Recently, exploiting reconfigurable intelligent surface (RIS) to induce randomness in quasi-static wireless channels has received significant research interest. However, the inherent spatial correlation among the RIS elements is rarely studied, which can alter the optimum physical-layer key generation (PLKG) approach in terms of KGR and randomness in the key sequence. Specifically, for the first time, in this contribution, we take into account a spatially correlated RIS, which intends to enhance the KGR in a quasi-static medium. Novel closed-form analytical expressions for KGR are derived for the two cases of random phase shift (RPS) and our proposed equal phase shift (EPS) in the RIS elements. We also analyze the correlation between the channel samples to ensure the randomness of the generated secret key sequence. It is shown that the EPS scheme can effectively exploit the inherent spatial correlation between the RIS elements and it leads to a higher KGR compared to the widely used RPS strategy. We further formulate an optimization problem in which we determine the optimal portion of time dedicated to direct and indirect channel estimation, which has never been addressed in previous studies. We show the accuracy and the fast convergence of our sequential convex programming (SCP)-based algorithm and discuss the various parameters affecting spatially correlated RIS-assisted PLKG.

IEEE Internet of Things JournalJan 2, 202424 citations

Reconfigurable intelligent surface-aided secret key generation using an autoencoder and K-means quantization

Zeyu Li, Panpan Xu, Qiangqiang Gao +2 more

In quasi-static wireless channel scenarios, the generation of physical layer keys faces the challenge of invariant spatial and temporal channel characteristics, resulting in a high key disagreement rate (KDR) and low key generation rate (KGR). To address these issues, we propose a novel reconfigurable intelligent surface (RIS)-aided secret key generation approach using an autoencoder and K -means quantization algorithm. The proposed method uses channel state information (CSI) for channel estimation and dynamically adjusts the reflection coefficients of the RIS to create a rapidly fluctuating channel. This strategy enables the extraction of dynamic channel parameters, thereby enhancing channel randomness. Additionally, by integrating the autoencoder with the K -means clustering quantization algorithm, the method efficiently extracts random bits from complex, ambiguous, and high-dimensional channel parameters, significantly reducing KDR. Simulations demonstrate that, under various signal-to-noise ratios (SNRs), the proposed method performs excellently in terms of KGR and KDR. Furthermore, the randomness of the generated keys is validated through the National Institute of Standards and Technology (NIST) test suite.

Frontiers of Information Technology & Electronic EngineeringAug 1, 20253 citations

Adaptive physical-layer key generation via RIS phase-shift matrix design in quasi-static environment

Qiangqiang Gao, Weijie Tan, Xin Cao +3 more

Abstract In quasi-static environment, the performance of physical-layer key generation (PKG) is limited by low entropy. Deploying reconfigurable intelligent surface (RIS) is a mainstream method to solve this problem. However, the secret key performance (SKP) is generally insufficient at low signal-to-noise ratio (SNR). In this paper, we propose an RIS-assisted adaptive PKG scheme. Specifically, we design phase based uniform quantization to enhance the randomness of the RIS channel while simplifying computations. Then, we present an RIS phase shift matrix design based on rejection sampling to adapt the quantization algorithm, which can reduce bit disagreement rate (BDR) and improve key generation rate (KGR). Furthermore, to balance the system’s requirements for low BDR and high KGR, we derive a theoretical model for estimating the BDR probability. By computing the theoretical BDR, we determine the maximum quantization order for different SNRs. Combined with a discard strategy, this enables adaptive selection of the quantization order. Simulation results demonstrate that the proposed scheme achieves lower BDR and higher KGR than existing approaches. Moreover, it does not require complex algorithms, making it suitable for resource-constrained internet of things scenarios. (RIS_Assist_PKG: https://github.com/GQQ1206/RIS_Assist_PKG )

Journal of King Saud University - Computer and Information SciencesAug 20, 20260 citations

RIS-Assisted Integration of Communications and Security: Protocol, Prototyping, and Field Trials

Zheng Wan, Kaizhi Huang, Xiaoming Xu +4 more

Reconfigurable intelligent surface (RIS), which can manipulate the wireless environment, has recently been integrated into physical-layer key generation (PKG) systems to establish randomness symmetric keys in static environments. However, few studies have jointly considered the optimization and randomization of the RIS elements to simultaneously achieve a high key generation rate (KGR) and communication performance. This study proposes a RIS-assisted communication and security-integrated protocol for dual-function integration of communication enhancement and PKG in static environments. The protocol partitions RIS elements for beamforming and random beams for parallel execution, utilizing a sparsity adaptive matching pursuit-based channel estimation algorithm to obtain individual channel state information. Subsequently, an optimization problem is formulated for KGR maximization while satisfying quality of service (QoS) requirements. The non-convex optimization problem is addressed through monotonicity analysis and triangle inequality. We validate the efficacy of the proposed protocol by developing a 4.9 GHz RIS-assisted PKG prototype system, comprising modular hardware and flexible software. The field trials demonstrate a 30.81 bit/s KGR for static environments with an average received power increase of 10.6 dB, achieving effective simultaneous integration of communication and security.

IEEE Internet of Things JournalApr 23, 202418 citations

Optimal Shifting Reconfigurable Intelligent Surface aided Physical-Layer Key Generation in Static Environments

Zheng Wan, Zhidan Wang, Mengyao Yan +4 more

This paper presents an optimal shifting scheme using reconfigurable intelligent surfaces (RIS) to aid physicallayer key generation (PKG) and enhance communication and key generation rate (KGR) in static environments. Our approach involves designing a protocol for RIS-aided key generation and optimizing RIS coefficients to introduce phase randomization in the wireless channel while maximizing power reception. Simulation results demonstrate the effectiveness of our proposed protocol in improving both communication performance and KGR under static conditions.

IEEE MTT-S International Wireless Symposium (IWS)May 16, 20240 citations

RIS-Assisted Multi-Carrier Secret Key Generation in Static Environments

Ji Hong Gu, Chongjun Ouyang, Xin Zhang +1 more

Physical layer key generation (PLKG) is a promising method to generate secret keys by harnessing the randomness of wireless channels. In this letter, a reconfigurable intelligent surface (RIS)-assisted multi-carrier PLKG framework is proposed to overcome the lack of channel randomness in static environments. Specifically, the secret key generation rate (SKGR) is analyzed based on the inter-frequency correlation among the channel coefficients across subcarriers. Building upon this analysis, a novel scheme for configuring RIS elements is proposed to enhance the SKGR by introducing correlations into the random phase shifts of RIS elements. Simulation results are presented to validate the effectiveness of the proposed scheme.

IEEE Wireless Communications LettersAug 16, 20241 citation