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.

ABSTRACT The development of reconfigurable intelligent surface (RIS) makes direction‐of‐arrival (DOA) estimation possible for single‐antenna receivers. However, non‐ideal situations such as spectral aliasing occur when facing communication signals using orthogonal frequency division multiplexing modulation. This paper proposes a RIS‐based single‐channel DOA estimation method for communication signals. Specifically, by extending the time intervals to dynamically reduce the RIS state change rate, a real‐time DOA estimation is achieved while mitigating the impact of non‐ideal spectral shifts on communication. Then, based on the compressed sensing and mutual incoherence property, the method exploits the sparse property of the signal in space to reduce the estimation time while improving the estimation accuracy. Simulation results show an reduction in computation time for the proposed method compared to the traditional CVX tool. Additionally, the estimation accuracy is as low as . To verify the practicality and robustness, we develop a prototype system and conduct extensive experiments. The results are consistent with our theoretical analysis, and the method proposed in this paper can realize single‐path DOA estimation with an accuracy of less than within . More excitingly, the presented experimental platform achieves DOA estimation for two coherent paths.

Abstract The reconfigurable intelligent surface (RIS) fundamentally changes the existing anti‐jamming paradigm by reconstructing the wireless propagation environment. However, the existing RIS‐based anti‐jamming work mainly considers narrow‐band frequency‐flat fading channels. As an extension of existing work, the use of RIS to enhance the anti‐jamming capability of broadband orthogonal frequency division multiplexing (OFDM) system in frequency‐selective fading channels is first studied. In the multipath frequency‐selective fading channels, the anti‐jamming design needs to satisfy the channel gains of all signal paths with different delays. To this end, the authors propose a joint design scheme of active precoding at the transmitter and passive precoding at the RIS to attenuate the jamming signal and enhance the legitimate signal, and formulate the joint design objective to maximize the average rate of all subcarriers. An alternating optimization algorithm is developed to address this non‐convex problem due to the complex coupling of active and passive precoding. In detail, the active and passive precoding are solved by the Cauchy–Schwarz inequality and power water‐filling method and the alternating direction method of multipliers method assisted by multidimensional complex quadratic transform, respectively. Simulation results demonstrate that the proposed method can significantly improve the anti‐jamming communication performance of the OFDM system compared with the scheme without RIS. In addition, the impact of the number of RIS elements and deployment location on system performance is revealed.

Abstract Confidentiality and authentication are two important security properties of wireless communication. There are currently two types of research in wireless communication security: one is based on cryptography, which can be too complicated for some wireless systems; the other is based on physical layer characteristics, which has some security problems and cannot work as well as the cryptography‐based method. In this paper, a lightweight encryption and message authentication framework for wireless communication is proposed. The proposed framework has lower complexity than the cryptography‐based method and works more securely and efficiently than the classical physical layer method. For the encryption, a physical layer offered chain key (PHYLOCK) structure is proposed to generate one‐time keys, which are then XOR‐ed with the plaintext to generate the ciphertext. A security analysis of PHYLOCK is performed and it is proved that it has better security features than the traditional physical layer key generation. For the message authentication, three types of PHYLOCK‐CRC‐based message authentication schemes are developed whose generator polynomial is determined by one‐time keys generated by PHYLOCK. PHYLOCK‐CRC‐based message authentication detects not only random errors introduced by noises but also malicious attacks. The error‐detecting and anti‐attack capabilities are analyzed mathematically. Compared to the standard CRC, PHYLOCK‐CRC‐based message authentication has a decline in error correction capability but is enhanced with cryptographic security features. Monte‐Carlo simulations are provided to evaluate the proposed scheme.

Due to the channel estimation error, most of the physical layer secret key generation schemes need information reconciliation to correct error key bits, resulting in reduced efficiency. To solve the problem, this work proposes a novel secure communication scheme based on a equivalent interference channel. Different keys generated from imperfect channel state information are directly applied to signal scrambling and descrambling, which is equivalent to the process of a signal passing through an interference channel. Legitimate communication parties can reduce interference with the help of similar keys and channel coding without sending additional signals, while the eavesdropper channel is deteriorated due to the spatial decorrelation. For this kind of schemes, we first establish a discrete memoryless broadcast channel model to derive the expressions of bit error rate (BER), channel capacity, and security capacity for performance analysis. Simulation results verify the derivations that the proposed scheme achieves secure communication with a correlated eavesdropping channel and has a higher upper bound of transmission rate. Furthermore, we design a new metric to evaluate the efficiency and the result shows that the proposed scheme has superior performance on error reconciliation efficiency, despite its slight increase in BER.