This paper presents the design and implementation of a new technology that can securely transfer symmetric encryption keys, e.g., Advanced Encryption Standard (AES) keys, over an optical fiber using a polarization-based channel. The integrity of the polarization channel against possible leakage of information is established. The polarization channel is used to transfer symmetric key information between the two parties using states of polarization (SoP) as the carrier of information and to detect presence of an intruder. Since the SoP is known to evolve during propagation along optical fiber, a correction matrix is applied to the received state to recover the original SoP. The information transferred over the corrected SoP forms the key for one or more channels on the fiber for symmetric encryption.
This paper presents the design and implementation of a new technology that can securely transfer symmetric encryption keys, e.g., Advanced Encryption Standard (AES) keys, over an optical fiber using a polarization-based channel. The integrity of the polarization channel against possible leakage of information is established. The polarization channel is used to transfer symmetric key information between the two parties using states of polarization (SoP) as the carrier of information and to detect presence of an intruder. Since the SoP is known to evolve during propagation along optical fiber, a correction matrix is applied to the received state to recover the original SoP. The information transferred over the corrected SoP forms the key for one or more channels on the fiber for symmetric encryption.
Optical fiber channels are used as media to transfer the information globally. This paper presents an implementation of a novel procedure using which a secured communication between two parties can be carried out using polarized beam of light over an optical fiber. The paper presents the experimental results obtained of the procedure in the lab environment and a security analysis of the same. It is observed that polarization state of a light pulse cannot be retained as it travels over an optical fiber because of the birefringence phenomenon. Multiple environmental factors such as pressure, vibration, temperature, etc. also add a non-linearity to the birefringence of an optical fiber leading towards an unpredictable polarization state changes over the course of an optical fiber. The proposed procedure helps the receiving party to successfully retrieve the data in the form of a polarization state transmitted by the sending party without having any knowledge about the state of polarization at the transmitting end. The paper also explains an added layer of security the procedure provides to the communicating parties to make it difficult for an adversary to fetch the data being transferred. The proposed system does not depend on the wavelength of the light being used, nor does it depend upon the type of the optical fiber used for the communication. Using this procedure, multiple bits of secured information can be sent over an optical fiber in a single polarized pulse and retrieved at the receiving end, also known as Polarization Shift Keying.
The rapid increase on the information sharing around the world, leads to an utmost requirement for capacity and bandwidth. However, the need for security in the transmission and storage of information is also of major importance. The use of quantum technologies provides a practical solution for secure communications systems. Quantum key distribution (QKD) was the first practical application of quantum mechanics, and nowadays it is the most developed one. In order to share secret keys between two parties can be used several methods of encoding. Due to its simplicity, the encoding into polarization is one of the most used. However, when we use optical fibers as transmission channels, the polarization suffers random rotations that may change the state of polarization (SOP) of the light initially sent to the fiber to a new one at the output. Thus, in order to enable real-time communication using this encoding method it is required the use of a dynamic control system. We describe a scheme of transmission of quantum information, which is based in the polarization encoding, and that allows to share secret keys through optical fibers without interruption. The dynamic polarization control system used in such scheme is described, both theoretically and experimentally. Their advantages and limitations for the use in quantum communications are presented and discussed.
The method and the scheme of multichannel quantum system of secure communication for transfer of confidential data on optical fiber are developed. The considered scheme combines quantum key distribution with quantum secure data transmission. Such approach does not give possibility to the eavesdropper to decipher that part of information, which he can receive before the detection. The suggested scheme provides higher security level of transferred confidential information, than known, which use traditional pro-tocols of symmetric enciphering in a combination to quantum key distribution. It is found out that for the transmission protected in such a way on optical fiber the choice of wavelengths of 850 and 1625 nanometers is optimum. It is found out that when using in such systems of the avalanche photo diode FD-115L it is possible to provide a speed of information transfer up to 0,8 Mbps in one channel. For increase in speed of transfer, it is proposed to use two and more channels of transfer.
The physical-layer properties of the classical optical fiber channel provide an inherent, unique, random and reciprocal source for secure key generation and distribution (SKGD). However, the key generation rate (KGR) is generally less than kbit/s in the reported SKGD schemes. In this paper, an accelerated SKGD scheme based on active polarization scrambling is proposed in the classical optical fiber channel. A combination of unique birefringence distribution of optical fiber channel and active scrambling of instant state of polarization (SOP) enables a fast and random SOP fluctuation to be securely shared between the legitimate users for accelerated SKGD. The proposed SKGD scheme is experimentally demonstrated over 24-km standard single-mode fiber (SSMF), where a KGR of 200-kbit/s with an error-free operation is achieved after the post-processing procedure. Moreover, the possible fiber-tapping attacks are theoretically and experimentally analyzed for the security robustness of the proposed scheme. The results imply that a faster SKGD scheme could be achieved by incorporating an active polarization scrambling mechanism into the random properties of the fiber channel.
The quantum key distribution (QKD) method allows for the safe creation of encryption keys between trusted entities for secure communication. The suggested system is designed to enable secure communication between multiple parties (a single sender, Alice, and multiple receivers, Bobs) connected via a public channel susceptible to interception. It enables Alice to privately share encryption keys with each Bob over dedicated quantum channels, which can then be used to decrypt messages sent over the public network. The procedure involves Alice generating optical signals with randomly assigned properties such as intensity, phase, polarization, and frequencies. Alice randomly sends either signal states carrying information or decoy states with different frequencies to the receivers (Bobs) over the quantum channels. She also sends a synchronization signal for timing alignment with the quantum signals over the optical links. At the receiving end, the synchronization pulse timestamps the incoming quantum signals. Each Bob then randomly alters the frequencies of the received quantum signals and randomly measures their phase or polarization. The key is created from the frequency, phase, or polarization information of the quantum signals, resulting in longer keys. Key management agents manage the securely QKD-generated keys to encrypt information before sending it to the intended receivers. Essentially, this framework establishes authenticated, private communication by using QKD over dedicated ultra-secure quantum links to distribute decryption keys, ensuring that only intended users can access the content. The approach is designed to ensure end-to-end secure communication across the network.
Dynamic properties of optical signals in fiber channel provide a unique, random and reciprocal source for physical-layer secure key generation and distribution (SKGD). In this paper, an inherent physical-layer SKGD scheme is proposed and demonstrated, where the random source is originated from the dynamic fluctuation of the instant state of polarization (SOP) of optical signals in fiber. Due to the channel reciprocity, highly-correlated fluctuation of Stokes parameter of SOP is shared between the legal partners, where an error-free key generation rate (KGR) of 196-bit/s is successfully demonstrated over 25-km standard single-mode fiber (SSMF). In addition, an active polarization scrambler is deployed in fiber to increase the KGR, where an error-free KGR of 200-kbit/s is achieved.