Optical fiber communication was widely believed that an optical network was a good way to prevent hacking through wiretaps which intercept network data. However, fiber optic cable is not particularly secure. Various tapping methods can be used to extract data from fiber optic networks with little or no risk of detection. One of the easiest ways of intruding into a fiber optic communication link is creating a bend on the fiber cable. Even small percentage of the transmitted light acquired with the bending method is enough for recovering the data by the attacker. Though there are some techniques and devices that can track the power and intensity inside the fiber cable, these methods cannot detect an attack exploiting small leakage. Therefore, it is critical to determine a range of radii of curvature for which tapping attacks are not detectable. Though there are some studies to quantify the power loss both theoretically and numerically, as of the authors' knowledge, there has not been any experimental validation of those studies. In this respect, an experimental optical setup and a technique relying on the ADC conversion capability of Arduino UNO to measure power loss resulting from different bending radii are proposed in this paper. A lower limit for radius of curvature for an attack to be undetected is obtained and the estimations in the literature for power loss resulting from fiber bending is validated.
Optical fiber communication was widely believed that an optical network was a good way to prevent hacking through wiretaps which intercept network data. However, fiber optic cable is not particularly secure. Various tapping methods can be used to extract data from fiber optic networks with little or no risk of detection. One of the easiest ways of intruding into a fiber optic communication link is creating a bend on the fiber cable. Even small percentage of the transmitted light acquired with the bending method is enough for recovering the data by the attacker. Though there are some techniques and devices that can track the power and intensity inside the fiber cable, these methods cannot detect an attack exploiting small leakage. Therefore, it is critical to determine a range of radii of curvature for which tapping attacks are not detectable. Though there are some studies to quantify the power loss both theoretically and numerically, as of the authors' knowledge, there has not been any experimental validation of those studies. In this respect, an experimental optical setup and a technique relying on the ADC conversion capability of Arduino UNO to measure power loss resulting from different bending radii are proposed in this paper. A lower limit for radius of curvature for an attack to be undetected is obtained and the estimations in the literature for power loss resulting from fiber bending is validated.
Optical chaos communication has a physical-layer security advantage but defends passively against a malicious attack. Here, we conduct a proof-of-concept experiment of detecting the attack proactively by observing performance degradation in optical chaos communication tapped with fiber bending. Influences of the curvature radius of the bent fiber on a chaos synchronization coefficient and bit error rate are investigated. Results show that the synchronization coefficient decreases from 0.958 to 0.904 and the bit error rate increases from 1.31 × 10 −4 to 1.73 × 10 −3 under a curvature radius of 10 mm, revealing the attack. Bending fiber to this extent leads to a power loss of 1.81%, which is difficult to detect by the optical time-domain reflectometer but causes significant interference to chaos communication due to the concurrent change in the light polarization, jointly decreasing the effective optical injection strength for yielding chaos synchronization.
Initially considered secure against interception, fiber-optic networks were subsequently found susceptible to covert tapping, although such attacks require different coupling mechanisms and components than those used for twisted pair and coaxial cables. Fiber-optic networks carry the majority of data and voice traffic worldwide, including backhaul and fronthaul traffic in 4G and 5G radio networks, connections between data centers, and submarine cable systems. Consequently, physical access to fibers for interception has attracted the attention of intelligence agencies and industrial spies. This vulnerability is facilitated by the fact that single-mode optical fibers (SMFs) used in telecommunication networks have evolved relatively little over the last 40 years. Fibers of substantially different designs—anti-resonant hollow core fibers (HCF) and multi-core fibers (MCF)—made their commercial debut around 2023, and their susceptibility to tapping may differ substantially from that of conventional SMFs. New promising fiber monitoring techniques based on polarization measurements have also been demonstrated recently. While established tapping techniques remain feasible for conventional fibers, new fiber designs and monitoring technologies can make covert interception difficult. This review examines physical fiber tapping techniques and their practical feasibility, with particular emphasis on optical power constraints, introduced loss, detectability, and implementation limitations. It also reviews prevention and monitoring approaches, including optical time-domain reflectometry, received-power monitoring, and state-of-polarization (SOP) monitoring, and provides a prospective engineering assessment of the susceptibility of MCFs and HCFs to physical tapping.
Optical fiber communication is not as secure as generally perceived. There are a number of known methods of extracting or injecting information into a fiber link, while avoiding detection. Few incidents have been reported as a successfully tapped fiber is difficult to detect. In this paper we highlight a number of known fiber tapping methods. We report simulation of optical characteristics of a fiber being tapped by `bend' method and proof of concept with physical experiment. We also presented visualized scenarios in which a resourceful eavesdropper can compromise security of a fiber link with existing technologies. Some measures to prevent fiber tapping or to nullify the significance of information tapped from fiber were also discussed.
Optical fiber communication networks are the backbone of information transmission, carrying over 90% of the world's data. However, optical fibers are susceptible to fiber-bending eavesdropping attacks, which can result in massive data leaks. The detection of fiber-bending eavesdropping attacks has become one of the effective strategies to safeguard data security. In this paper, we propose a detection scheme based on a convolutional neural network (CNN) for detecting fiber-bending eavesdropping attacks in dual-polarization coherent optical communication systems. To validate the feasibility and effectiveness of the proposed scheme, we first establish the relationship between the fiber-bending radius and the bending power loss coefficient. Based on this relationship, a 100 km, 25 GBaud dual-polarization 16 quadrature amplitude modulation (16QAM) coherent optical communication system is constructed. This system collects both normal polarization data and bending eavesdropping polarization data. Subsequently, the performance of the CNN algorithm in detecting fiber-bending eavesdropping attacks is evaluated. The results show that under bending radii of 10.8 mm, 12.1 mm, 15 mm, and mixed bending radii, the eavesdropping detection accuracy rates of the CNN reach 99.8%, 99.67%, 99.22%, and 96.15%, respectively.
Fiber optic cables have long been considered a secure medium that prevents eavesdropping due to their complexity. However, there are attack methods that allow eavesdropping or denial of service. These include methods based on bending optical fibers. The danger resides in the possibility of being able to carry out an attack without having to interrupt the path. To facilitate such attacks, it is possible to use a clip-on coupler. This coupler is designed to allow eavesdropping on the link without interruption. In this study, we focus on evaluating the coupling efficiency of a simple but commercially available clip-on coupler. This work investigates the effectiveness of jamming into the optical link, i.e., replicating the jamming attack and measuring it by simulating real traffic conditions. To better understand the complexity of these attacks, we perform additional measurements to investigate the effect of clip-on coupling on changes in the polarization state. Through this research, we highlight the increasing vulnerability of optical fibers to eavesdropping attempts, especially those using macro-based methods. By evaluating the performance of commercially available clip-on coupling, we provide valuable insights into potential risks and mitigation strategies for securing modern optical communication networks.
One important advantage of fiberoptic communication is security. Compared with conventional electric cables, optical fiber cables are very hard to tap on information because no elctric or magnetic fields are generated from the cables. However, it is still possible to make an optical fiber to leak some of its power by peeling the jacket and bending the fiber or removing the cladding. Methods to pro-tect fiberoptic communication from tapping has been proposedl). In this paper we propose a new, simple but effective method bases on intermodal interference to protect multimode fiberoptic communication. The optical fiber detects any mechanical distortion of itself, which unavoidably occurs in an attempt to tap information. Although the lightwave carries both communication and security informations, we demonstrate that there is no degradation in communication quality.