Optical networks’ physical layer is vulnerable to a variety of attacks, such as jamming, eavesdropping, and, finally, interception. Optical technology may have focused mainly on the more bandwidth race, but the issue of securing the physical layer needs the proper attention. In this paper we survey on recent progress in Optical Frequency Hopping (OFH) techniques used for securing fiber-optic networks and discuss up to date experimental demonstrations. Furthermore, we study on how this technique can effectively improve security for a variety of optical network technologies. Finally, we comment on OFH research challenges and address fields of possible future interest.
Optical networks’ physical layer is vulnerable to a variety of attacks, such as jamming, eavesdropping, and, finally, interception. Optical technology may have focused mainly on the more bandwidth race, but the issue of securing the physical layer needs the proper attention. In this paper we survey on recent progress in Optical Frequency Hopping (OFH) techniques used for securing fiber-optic networks and discuss up to date experimental demonstrations. Furthermore, we study on how this technique can effectively improve security for a variety of optical network technologies. Finally, we comment on OFH research challenges and address fields of possible future interest.
The physical layer of an optical network is vulnerable to a variety of attacks, including jamming, physical infrastructure attacks, eavesdropping, and interception. As the demand for network capacity grows dramatically, the issue of securing the physical layer of optical network cannot be overlooked. In this survey paper, we discuss the security threats in an optical network as well as present several existing optical techniques to improve the security. In the first part of this paper, we discuss various types of security threats that could appear in the optical layer of an optical network, including jamming, physical infrastructure attacks, eavesdropping, and interception. Intensive research has focused on improving optical network security, in the above specific areas. Real-time processing of the optical signal is essential in order to integrate security functionality at the physical layer while not undermining the true value of optical communications, which is its speed. Optical layer security benefits from the unique properties of optical processing-instantaneous response, broadband operation, electromagnetic immunity, compactness, and low latency. In the second part of this paper, various defenses against the security threats outlined in this paper are discussed, including optical encryption, optical code-division multiple access (CDMA) confidentiality, self-healing survivable optical rings, anti-jamming, and optical steganography.
At present, the optical fiber transmission technology is developing more and more rapidly. In the meantime, the discussion on the security issues triggered by it has become more and more intense. Based on this, this article summarizes the mainstream methods for improving the security of optical fiber transmission technology at the present stage. This can provide the certain reference direction for future research and exploration. Currently certain accomplishments have been attained in the physical layer, management layer, the network layer, the encryption technology, and the access control. But at the same time, there are also some disadvantages in certain aspects. For example, the complexity of the encryption technology is too high, the cost of the management layer is too excessive, and the difficulty of constructing the network layer is too great. In the future, more in-depth research can be conducted in material improvement, intelligent management, optimization of encryption technology, construction of secure networks, and detection of intrusion signals. This will further enhance the security of optical fiber transmission technology.
As the existing radio-frequency (RF) networks cannot meet the ever-increasing data rate demand, the optical wireless communication (OWC), which uses a wide untapped unregulated spectrum, has been proposed as a promising technology to overcome the RF spectrum limitations. On the other hand, with the increasing demand for high data rate and the prevalence of the broadcast-nature networks, researchers have recently come up with new mechanisms to improve secure communication using physical layer techniques. Compared to RF networks, the OWC networks are more secure and less susceptible to the interception because of the small coverage provided by LEDs, and because they work properly only in the presence of the line-of-sight (LoS) components. However, the security in OWC networks is still an issue, especially in visible light communication (VLC) when the transmitted information can be accessed by multiple users as in public areas, meeting rooms, laboratories, and libraries. That means potential eavesdroppers may be existing to gather confidential messages. This paper reviews all the conducted work on physical layer security (PLS) in two types of OWC networks, which are the VLC and free space optical (FSO) networks. Furthermore, the paper proposes several open problems in these networks to optimize and enhance the security performance.
Physical layer security (PLS) is becoming a fundamental requirement in both present and next-generation optical networks, driven by the emerging threat imposed by the immense processing power of quantum computers. To address the need for cost-effective PLS solutions suitable for economically sensitive optical access networks, we have proposed and experimentally demonstrated a DSP-enabled PLS technique offering retrofittable compatibility with existing optical networks and a purely DSP-based solution for seamless digital integration in future communication systems. This paper presents an overview of the proposed techniques, including details of operating principles, experimental validations and investigations, prototype development, and field trials.
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.
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.