Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of Lightwave Technology

Tapping Eavesdropper Designs Against Physical Layer Secret Key in Point-to-Point Fiber Communications

Wenxiu Hu, Zhuangkun Wei, Sergei Popov, Mark Stephen Leeson, Tianhua Xu

Published Nov 17, 2022• 15 citations
Publisher

Abstract

With the growing demand for service access and data transmission, security issues in optical fiber systems have become increasingly important and the subject of increased research. Physical layer secret key generation (PL-SKG), which leverages the random but common channel properties at legitimate parties, has been shown to be a secure, low-cost, and easily deployed technique as opposed to computational-based cryptography, quantum, and chaos key methods that rely on precise equipment. However, the eavesdropper (Eve) potential for current PL-SKG in fiber communications has been overlooked by most studies to date. Unlike wireless communications, where the randomness comes from the spatial multi-paths that cannot be all captured by Eves, in fiber communications, all the randomness (from transmitted random pilots or channel randomness) is contained in the signals transmitted inside the fiber. This, therefore, enables a tapping Eve to reconstruct the common features of legitimate users from its received signals, and further decrypt the featured-based secret keys. To implement this idea, we designed two Eve schemes against polarization mode distortion (PMD) based PL-SKG and the two-way cross multiplication based PL-SKG. The simulation results show that our proposed Eves can successfully reconstruct the legitimate common feature and the secret key relied upon, leading to secret key rate (SKR) reductions of between three and four orders of magnitude in the PL-SKG schemes studied. As a result, we reveal and demonstrate a novel eavesdropping potential to provide challenges for current physical layer secret key designs. We hope to provide more insightful vision and critical evaluation on the design of new physical layer secret key schemes in optical fiber links, to provide more comprehensively secure, and intelligent optical networks.

DOI
10.1109/jlt.2022.3223025

Related papers

Random Matrix based Physical Layer Secret Key Generation in Static Channels

Zhuangkun Wei, Weisi Guo

Physical layer secret key generation exploits the reciprocal channel randomness for key generation and has proven to be an effective addition security layer in wireless communications. However, static or scarcely random channels require artificially induced dynamics to improve the secrecy performance, e.g., using intelligent reflecting surface (IRS). One key challenge is that the induced random phase from IRS is also reflected in the direction to eavesdroppers (Eve). This leakage enables Eve nodes to estimate the legitimate channels and secret key via a globally known pilot sequence. To mitigate the secret key leakage issue, we propose to exploit random matrix theory to inform the design of a new physical layer secret key generation (PL-SKG) algorithm. We prove that, when sending appropriate random Gaussian matrices, the singular values of Alice's and Bob's received signals follow a similar probability distribution. Leveraging these common singular values, we propose a random Gaussian matrix based PL-SKG (RGM PL-SKG), which avoids the usages of the globally known pilot and thereby prevents the aforementioned leakage issue. Our results show the following: (i) high noise resistance which leads to superior secret key rate (SKR) improvement (up to 300%) in low SNR regime, and (ii) general improved SKR performance against multiple colluded Eves. We believe our combination of random matrix theory and PL-SKG shows a new paradigm to secure the wireless communication channels.

arXiv:2110.12785•Oct 25, 2021•3 citations

Eavesdropping Against Bidirectional Physical Layer Secret Key Generation in Fiber Communications

Wenxiu Hu, Zhuangkun Wei, Mark Stephen Leeson +1 more

Physical layer secret key exploits the random but reciprocal channel features between legitimate users to encrypt their data against fiber-tapping. We propose a novel tapping-based eavesdropper scheme, leveraging its tapped signals from legitimate users to reconstruct their common features and the secret key.

IEEE Photonics Conference•Nov 1, 2022•6 citations

Adversarial Reconfigurable Intelligent Surface Against Physical Layer Key Generation

Zhuangkun Wei, Bin Li, Weisi Guo

The development of reconfigurable intelligent surfaces (RIS) has recently advanced the research of physical layer security (PLS). Beneficial impacts of RIS include but are not limited to offering a new degree-of-freedom (DoF) for key-less PLS optimization, and increasing channel randomness for physical layer secret key generation (PL-SKG). However, there is a lack of research studying how adversarial RIS can be used to attack and obtain legitimate secret keys generated by PL-SKG. In this work, we show an Eve-controlled adversarial RIS (Eve-RIS), by inserting into the legitimate channel a random and reciprocal channel, can partially reconstruct the secret keys from the legitimate PL-SKG process. To operationalize this concept, we design Eve-RIS schemes against two PL-SKG techniques used: (i) the CSI-based PL-SKG, and (ii) the two-way cross multiplication based PL-SKG. The channel probing at Eve-RIS is realized by compressed sensing designs with a small number of radio-frequency (RF) chains. Then, the optimal RIS phase is obtained by maximizing the Eve-RIS inserted deceiving channel. Our analysis and results show that even with a passive RIS, our proposed Eve-RIS can achieve a high key match rate with legitimate users, and is resistant to most of the current defensive approaches. This means the novel Eve-RIS provides a new eavesdropping threat on PL-SKG, which can spur new research areas to counter adversarial RIS attacks.

arXiv:2206.10955•IEEE Transactions on Information Forensics and Security•Jan 1, 2023•33 citations

Physical Layer Security Key Generation for Fiber Optic and Inter-Vehicular Optical Communication Link

Imam Uz Zaman

Point to Point Optical Link (PPOL) and Inter Vehicular Visible Light Communications (IVVLC) as susceptible to many security threats including jamming, eavesdropping, interception and physical infrastructure attack. To address this problem, researchers have recently proposed to generate secret keys from the randomness of the physical environment such as wireless communication channel fading characteristics, phase fluctuation inside optical fiber and polarization mode dispersion in a long-haul network. In this thesis, I presented a novel symmetric physical layer based secret key generation schemes for both PPOL and IVVLC. Polarization Mode Dispersion (PMD) of long optical fiber links and intensity variations due to road surface roughness along with driving behavior are exploited as a random channel characteristic to generate cryptographic keys for PPOL and IVVLC, respectively. It has been demonstrated, modulation of a probe signal caused by PMD in a high speed PPOL (40Gb/s and 60Gb/s) is reciprocal with average Pearson correlation coefficient of 0.862, despite the presence of optical nonlinearities, dispersion, and noise in the system. 128-bit symmetric cryptographic key has been successfully generated using the proposed scheme. Moreover, PMD based encryption keys passed the National Institute of Standards and Technology (NIST) tests. It is proved through simulations of a 50km link that, with optimal key generation settings, symmetric keys can be generated with high randomness (high P-values for NIST randomness tests) and with sufficient generation rates (>50%). Furthermore, this key generation algorithm successfully generated, with extremely low error, high entropy, secret keys with lengths up to 128-bits using a 1kbps probe signal with the proposed scheme. It is also found that the vehicular visible light channels have high entropy (e.g., 12-14 bits for 5000 samples) and that separate channels are highly uncorrelated to one another (e.g., Pearson correlation coefficient of 0.32). These results prove that physical communication channel can be exploited to generate symmetric cryptographic keys.

•Jan 1, 2018•0 citations

Secret Key Generation Over Multi-Mode Fiber: Channel Measurements, Key Rate Analysis, and System Implementation

Pin-Hsun Lin, Paul Nowitzki, Eduard Axel Jorswieck +2 more

Secret keys are critical for many security mechanisms including secure data transmission. An efficient secret key generation and sharing scheme enhances the secure transmission rate. Meanwhile, secret keys are scarce resources for classical encryption schemes like the Rivest-Shamir-Adleman (RSA) cryptosystem and its post-quantum security counterparts in quantum applications. Therefore, harnessing every available random source for secret key extraction is crucial for maximizing the key rate across a range of potential applications. In this paper, we investigate the achievable rate of the secret key generation (SKG)-channel-model based on an actual measured multi-mode fiber (MMF) channel, where there is an additional public discussion channel between the legitimate parties, which the adversary can perfectly overhear. In particular, we first measure the MMF transmission matrix using digital holography, then design power allocation schemes among the modes. Our schemes can achieve a positive secret key rate at 51.3 bit per channel use, under a mode-dependent loss of 1 dB and a transmit power of 20 dBm. In addition, we implement an SKG system via MMF by explicitly designing the wiretap codes and discussion protocol. More specifically, we design the hash function and point-to-point channel encoder/decoder for each mode in the MMF based on Hayashi’s wiretap coding. The designed system can achieve a secret key rate-leakage trade-off at$R_{SK} = 23.6$bits per channel use and an average leakage rate at$ 4.22 \cdot 10^{-3}$bits per channel use per mode, at the transmit power$\textsf {P}_{T}$at 50 dBm and mode-dependent loss at 1 dB with the error probability constraint at Bob as$10^{-5}$. This demonstrates the feasibility and effectiveness of generating SKG via MMF, aligning with the common approaches of post-quantum cryptography and quantum key distribution in addressing the challenges posed by emerging quantum computers.

IEEE Open Journal of the Communications Society•Jan 1, 2025•3 citations

Physical-Layer Secret Key Generation in Power Line Communication Networks

Jiarui Zhang, Xiaosheng Liu, Ying Cui +1 more

Due to the inherent broadcast nature, power line communication (PLC) is vulnerable to eavesdropping. Traditionally, the secret keys are generated/distributed by pre-shared keys, adaptive tone mapping, or asymmetric encryption algorithm. All of these methods face problems such as high computational complexity, high cost, or less security. To solve the problem, a physical layer security (PLS)-based secret key generation (SKG) scheme aiming at the typical in-home broadband PLC network is proposed in this paper. However, the slowly time-varying characteristic and the serious noise interference in PLC channels will degrade the performance of the PLS-based SKG scheme. To break through the limitation of the randomness of PLC channels, two-way random signals are introduced. To make the SKG system more resistant to noise, the channel frequency response-based adaptive quantization (CFR-AQ) algorithm is designed, in which the amplitude threshold and the quantization level are adaptive to the noise power and the target key disagreement rate (KDR) to maximize the key generation rate (KGR). The performance is analyzed in two scenarios: single eavesdropper and multiple eavesdroppers. The simulation results demonstrate that the proposed scheme has a good overall performance in terms of KDR, KGR, and security with a lower complexity in the presence of single or multiple non-collusive eavesdroppers, and it can be regarded as an alternative solution to generate secret keys in PLC networks.

IEEE Access•Jan 1, 2022•19 citations
With the growing demand for service access and data transmission, security issues in optical fiber systems have become increasingly important and the subject of increased research. Physical layer secret key generation (PL-SKG), which leverages the random but common channel properties at legitimate parties, has been shown to be a secure, low-cost, and easily deployed technique as opposed to computational-based cryptography, quantum, and chaos key methods that rely on precise equipment. However, the eavesdropper (Eve) potential for current PL-SKG in fiber communications has been overlooked by most studies to date. Unlike wireless communications, where the randomness comes from the spatial multi-paths that cannot be all captured by Eves, in fiber communications, all the randomness (from transmitted random pilots or channel randomness) is contained in the signals transmitted inside the fiber. This, therefore, enables a tapping Eve to reconstruct the common features of legitimate users from its received signals, and further decrypt the featured-based secret keys. To implement this idea, we designed two Eve schemes against polarization mode distortion (PMD) based PL-SKG and the two-way cross multiplication based PL-SKG. The simulation results show that our proposed Eves can successfully reconstruct the legitimate common feature and the secret key relied upon, leading to secret key rate (SKR) reductions of between three and four orders of magnitude in the PL-SKG schemes studied. As a result, we reveal and demonstrate a novel eavesdropping potential to provide challenges for current physical layer secret key designs. We hope to provide more insightful vision and critical evaluation on the design of new physical layer secret key schemes in optical fiber links, to provide more comprehensively secure, and intelligent optical networks.
Physical layer secret key generation exploits the reciprocal channel randomness for key generation and has proven to be an effective addition security layer in wireless communications. However, static or scarcely random channels require artificially induced dynamics to improve the secrecy performance, e.g., using intelligent reflecting surface (IRS). One key challenge is that the induced random phase from IRS is also reflected in the direction to eavesdroppers (Eve). This leakage enables Eve nodes to estimate the legitimate channels and secret key via a globally known pilot sequence. To mitigate the secret key leakage issue, we propose to exploit random matrix theory to inform the design of a new physical layer secret key generation (PL-SKG) algorithm. We prove that, when sending appropriate random Gaussian matrices, the singular values of Alice's and Bob's received signals follow a similar probability distribution. Leveraging these common singular values, we propose a random Gaussian matrix based PL-SKG (RGM PL-SKG), which avoids the usages of the globally known pilot and thereby prevents the aforementioned leakage issue. Our results show the following: (i) high noise resistance which leads to superior secret key rate (SKR) improvement (up to 300%) in low SNR regime, and (ii) general improved SKR performance against multiple colluded Eves. We believe our combination of random matrix theory and PL-SKG shows a new paradigm to secure the wireless communication channels.
The development of reconfigurable intelligent surfaces (RIS) has recently advanced the research of physical layer security (PLS). Beneficial impacts of RIS include but are not limited to offering a new degree-of-freedom (DoF) for key-less PLS optimization, and increasing channel randomness for physical layer secret key generation (PL-SKG). However, there is a lack of research studying how adversarial RIS can be used to attack and obtain legitimate secret keys generated by PL-SKG. In this work, we show an Eve-controlled adversarial RIS (Eve-RIS), by inserting into the legitimate channel a random and reciprocal channel, can partially reconstruct the secret keys from the legitimate PL-SKG process. To operationalize this concept, we design Eve-RIS schemes against two PL-SKG techniques used: (i) the CSI-based PL-SKG, and (ii) the two-way cross multiplication based PL-SKG. The channel probing at Eve-RIS is realized by compressed sensing designs with a small number of radio-frequency (RF) chains. Then, the optimal RIS phase is obtained by maximizing the Eve-RIS inserted deceiving channel. Our analysis and results show that even with a passive RIS, our proposed Eve-RIS can achieve a high key match rate with legitimate users, and is resistant to most of the current defensive approaches. This means the novel Eve-RIS provides a new eavesdropping threat on PL-SKG, which can spur new research areas to counter adversarial RIS attacks.
Point to Point Optical Link (PPOL) and Inter Vehicular Visible Light Communications (IVVLC) as susceptible to many security threats including jamming, eavesdropping, interception and physical infrastructure attack. To address this problem, researchers have recently proposed to generate secret keys from the randomness of the physical environment such as wireless communication channel fading characteristics, phase fluctuation inside optical fiber and polarization mode dispersion in a long-haul network. In this thesis, I presented a novel symmetric physical layer based secret key generation schemes for both PPOL and IVVLC. Polarization Mode Dispersion (PMD) of long optical fiber links and intensity variations due to road surface roughness along with driving behavior are exploited as a random channel characteristic to generate cryptographic keys for PPOL and IVVLC, respectively. It has been demonstrated, modulation of a probe signal caused by PMD in a high speed PPOL (40Gb/s and 60Gb/s) is reciprocal with average Pearson correlation coefficient of 0.862, despite the presence of optical nonlinearities, dispersion, and noise in the system. 128-bit symmetric cryptographic key has been successfully generated using the proposed scheme. Moreover, PMD based encryption keys passed the National Institute of Standards and Technology (NIST) tests. It is proved through simulations of a 50km link that, with optimal key generation settings, symmetric keys can be generated with high randomness (high P-values for NIST randomness tests) and with sufficient generation rates (>50%). Furthermore, this key generation algorithm successfully generated, with extremely low error, high entropy, secret keys with lengths up to 128-bits using a 1kbps probe signal with the proposed scheme. It is also found that the vehicular visible light channels have high entropy (e.g., 12-14 bits for 5000 samples) and that separate channels are highly uncorrelated to one another (e.g., Pearson correlation coefficient of 0.32). These results prove that physical communication channel can be exploited to generate symmetric cryptographic keys.
Secret keys are critical for many security mechanisms including secure data transmission. An efficient secret key generation and sharing scheme enhances the secure transmission rate. Meanwhile, secret keys are scarce resources for classical encryption schemes like the Rivest-Shamir-Adleman (RSA) cryptosystem and its post-quantum security counterparts in quantum applications. Therefore, harnessing every available random source for secret key extraction is crucial for maximizing the key rate across a range of potential applications. In this paper, we investigate the achievable rate of the secret key generation (SKG)-channel-model based on an actual measured multi-mode fiber (MMF) channel, where there is an additional public discussion channel between the legitimate parties, which the adversary can perfectly overhear. In particular, we first measure the MMF transmission matrix using digital holography, then design power allocation schemes among the modes. Our schemes can achieve a positive secret key rate at 51.3 bit per channel use, under a mode-dependent loss of 1 dB and a transmit power of 20 dBm. In addition, we implement an SKG system via MMF by explicitly designing the wiretap codes and discussion protocol. More specifically, we design the hash function and point-to-point channel encoder/decoder for each mode in the MMF based on Hayashi’s wiretap coding. The designed system can achieve a secret key rate-leakage trade-off atRSK=23.6R_{SK} = 23.6RSK​=23.6bits per channel use and an average leakage rate at$ 4.22 \cdot 10^{-3}bitsperchannelusepermode,atthetransmitpowerbits per channel use per mode, at the transmit powerbitsperchannelusepermode,atthetransmitpower\textsf {P}_{T}$at 50 dBm and mode-dependent loss at 1 dB with the error probability constraint at Bob as10−510^{-5}10−5. This demonstrates the feasibility and effectiveness of generating SKG via MMF, aligning with the common approaches of post-quantum cryptography and quantum key distribution in addressing the challenges posed by emerging quantum computers.
Due to the inherent broadcast nature, power line communication (PLC) is vulnerable to eavesdropping. Traditionally, the secret keys are generated/distributed by pre-shared keys, adaptive tone mapping, or asymmetric encryption algorithm. All of these methods face problems such as high computational complexity, high cost, or less security. To solve the problem, a physical layer security (PLS)-based secret key generation (SKG) scheme aiming at the typical in-home broadband PLC network is proposed in this paper. However, the slowly time-varying characteristic and the serious noise interference in PLC channels will degrade the performance of the PLS-based SKG scheme. To break through the limitation of the randomness of PLC channels, two-way random signals are introduced. To make the SKG system more resistant to noise, the channel frequency response-based adaptive quantization (CFR-AQ) algorithm is designed, in which the amplitude threshold and the quantization level are adaptive to the noise power and the target key disagreement rate (KDR) to maximize the key generation rate (KGR). The performance is analyzed in two scenarios: single eavesdropper and multiple eavesdroppers. The simulation results demonstrate that the proposed scheme has a good overall performance in terms of KDR, KGR, and security with a lower complexity in the presence of single or multiple non-collusive eavesdroppers, and it can be regarded as an alternative solution to generate secret keys in PLC networks.