The attacker can manipulate a reconfigurable intelligent surface (RIS) to jamming attack to break the channel reciprocity, resulting in an increasing key disagreement rate (KDR) to interrupt the physical layer key generation (PKG). In this letter, a countermeasure for PKG is proposed to resist the RIS jamming attack. The proposed countermeasure includes the atomic norm minimization (ANM)-based multipath separation algorithm and statistic feature-based path detection algorithm, which can reconstruct the reciprocal channel without needing a wide frequency band. Simulation results show that the proposed countermeasure can significantly reduce KDR from 0.33 to 0.03 when SNR is 10 dB and achieve an excellent key generation rate (KGR) compared with existing schemes.
The attacker can manipulate a reconfigurable intelligent surface (RIS) to jamming attack to break the channel reciprocity, resulting in an increasing key disagreement rate (KDR) to interrupt the physical layer key generation (PKG). In this letter, a countermeasure for PKG is proposed to resist the RIS jamming attack. The proposed countermeasure includes the atomic norm minimization (ANM)-based multipath separation algorithm and statistic feature-based path detection algorithm, which can reconstruct the reciprocal channel without needing a wide frequency band. Simulation results show that the proposed countermeasure can significantly reduce KDR from 0.33 to 0.03 when SNR is 10 dB and achieve an excellent key generation rate (KGR) compared with existing schemes.
Channel Reciprocity-based Key Generation (CRKG) exploits reciprocal channel randomness to establish shared secret keys between wireless terminals. This new security technique is expected to complement existing cryptographic techniques for secret key distribution of future wireless networks. In this paper, we present a new attack, reconfigurable intelligent surface (RIS) jamming, and show that an attacker can prevent legitimate users from agreeing on the same key by deploying a malicious RIS to break channel reciprocity. Specifically, we elaborate on three examples to implement the RIS-jamming attack: Using active nonreciprocal circuits, performing time-varying controls, and reducing the signal-to-noise ratio. The attack effect is then studied by formulating the secret key rate with a relationship to the deployment of RIS. To resist such RIS-jamming attacks, we propose a countermeasure that exploits wideband signals for multipath separation. The malicious RIS path is distinguished from all separated channel paths, and thus the countermeasure is referred to as contaminated path removal-based CRKG (CPR-CRKG). We present simulation results, showing that legitimate users under RIS jamming are still able to generate secret keys from the remaining paths. We also experimentally demonstrate the RIS-jamming attack by using commodity Wi-Fi devices in conjunction with a fabricated RIS prototype. In our experiments, we were able to increase the average bit disagreement ratio (BDR) of raw secret keys by 20%. Further, we successfully demonstrate the proposed CPR-CRKG countermeasure to tackle RIS jamming in wideband systems as long as the source of randomness and the RIS propagation paths are separable.
Reconfigurable Intelligent Surface (RIS) is a new paradigm that enables the reconfiguration of the wireless environment. Based on this feature, RIS can be employed to facilitate Physical-layer Key Generation (PKG). However, this technique could also be exploited by the attacker to destroy the key generation process via manipulating the channel features at the legitimate user side. Specifically, this paper proposes a new RIS-assisted Manipulating attack (RISM) that reduces the wireless channel reciprocity by rapidly changing the RIS reflection coefficient in the uplink and downlink channel probing step in orthogonal frequency division multiplexing (OFDM) systems. The vulnerability of traditional key generation technology based on channel frequency response (CFR) under this attack is analyzed. Then, we propose a slewing rate detection method based on path separation. The attacked path is removed from the time domain and a flexible quantization method is employed to maximize the Key Generation Rate (KGR). The simulation results show that under RISM attack, when the ratio of the attack path variance to the total path variance is 0.17, the Bit Disagreement Rate (BDR) of the CFR-based method is greater than 0.25, and the KGR is close to zero. In addition, the proposed detection method can successfully detect the attacked path for SNR above 0 dB in the case of 16 rounds of probing and the KGR is 35 bits/channel use at 23.04MHz bandwidth.
Physical layer key generation (PKG) is a promising means to provide on-the-fly shared secret keys by exploiting the intrinsic randomness of the radio channel. However, the performance of PKG is highly dependent on the propagation environments. Due to its feature of controlling the wireless environment, reconfigurable intelligent surface (RIS) is appealing to be applied in PKG. In this article, in contrast to the existing literature, we investigate both the constructive and destructive effects of RIS on the PKG scheme. For the constructive aspect, we have identified static and wave-blockage environments as two RIS-empowered-PKG applications in future wireless systems. In particular, our experimental results in a static environment showed that RIS can enhance the entropy of the secret key, achieving a key generation rate (KGR) of 97.39 bit/s with a bit disagreement rate (BDR) of 0.083. In multi-user systems where some remote users are in worse channel conditions, the proposed RIS-assisted PKG algorithm improves the sum secret key rate by more than 2 dB, compared to the literature. Furthermore, we point out that RIS could be utilized by an attacker to perform new jamming and leakage attacks and give countermeasures, respectively. Finally, we outline future research directions for PKG systems in light of the RIS.
With the rapid development of wireless communication, the traditional communication encryption method is not adequate for our needs of high-speed and low latency. As a consequence, Physical Layer-Key Generation (PKG) and Reconfigurable Intelligent Surface (RIS) emerged. The existing researches on the combination of PKG and RIS mainly focus on the randomness increase of the communication environment and the key generation rate under a quasi-static environment. On the other hand, there is little research on the active attack of RIS by eavesdroppers. In this paper, the attack and defense method based on the combination of RIS and PKG is discussed. We propose a random phase attack method derived from the multiple-input single-output (MISO) model and analyze the effectiveness of the attack. To resist the random phase attack under a hypothetical scenario in which RIS is under the control of the attacker, we propose a path separation and path detection defense method according to the Multiple Signal Classification (MUSIC) algorithm. Simulation results show that the Bit Disagreement Rate (BDR) achieves a significant reduction, which proves the effectiveness of the proposed defense method based on path detection and path separation.
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 )
Physical layer key generation (PKG) is a promising means to provide on-the-fly shared secret keys by exploiting the intrinsic randomness of the radio channel. However, the performance of PKG is highly dependent on the wireless propagation environment. Due to its feature of controlling the wireless environment, reconfigurable intelligent surface (RIS) is appealing to be applied in PKG. In this chapter, we explore the effects of RIS on PKG from both constructive and destructive perspectives. For the constructive aspect, we have identified static and wave-blockage environments as two RIS-empowered-PKG applications in future wireless systems. Furthermore, we also point out that RIS could be utilized by an attacker to perform new jamming and leakage attacks and provide countermeasures, respectively. At last, possible directions for future research have also been given.