Cryptography in communications is of increasing importance and several sophisticated cryptographic algorithms have been developed. Quantum mechanical principles have been employed yielding cryptographic keys to generate ciphertext, especially applicable to optical communications, and which are believed to be unbreakable. In optical communications, the quantum ciphertext is the bit-by-bit exclusive-Or (XOR) operation of the quantum key and the text. Thus, an all-optical XOR gate is required at the transmitter, which for compactness and efficiency it should be simple and monolithically integrable. In this paper we review the quantum ciphertext generation, and we present a novel XOR gate that requires a single wavelength, in contrast to other solutions that require additional optical signals for control and synchronization. Simulation results support the viability of our novel all-optical XOR gate at data rates up to 40 Gbps.
Cryptography in communications is of increasing importance and several sophisticated cryptographic algorithms have been developed. Quantum mechanical principles have been employed yielding cryptographic keys to generate ciphertext, especially applicable to optical communications, and which are believed to be unbreakable. In optical communications, the quantum ciphertext is the bit-by-bit exclusive-Or (XOR) operation of the quantum key and the text. Thus, an all-optical XOR gate is required at the transmitter, which for compactness and efficiency it should be simple and monolithically integrable. In this paper we review the quantum ciphertext generation, and we present a novel XOR gate that requires a single wavelength, in contrast to other solutions that require additional optical signals for control and synchronization. Simulation results support the viability of our novel all-optical XOR gate at data rates up to 40 Gbps.
This paper presents a study of magneto-optical waveguide logic gates for optical communication systems. Simple logic operations are implemented by modulating photon states in a material through applied magnetic fields. By controlling the magnetic field's amplitude and orientation relative to light propagation, selecting polarizer/analyzer alignment, and configuring waveguides, we designed logic gates including qubit-compatible models that overcome the low coherence times typical of optical qubits. Optical qubits are promising candidates for quantum information processing and data transmission. For cryptographic applications using Vernam encryption, we developed an XOR logic gate simulator based on magneto-optical principles. Experimental validation employed ASCII encoding and text encryption/decryption algorithms, demonstrating successful cryptographic processing of confidential data over fiber-optic lines. The results show that magneto-optical qubit control mechanisms enable modeling diverse waveguide-based logic gates, including a half adder performing parallel XOR and AND operations. These devices facilitate novel information processing and transmission architectures.
Secure optical communication technologies are important means to solve the physical layer security for optical network. We present a scheme of secure optical communication system by all-optical signal processing technique. The scheme consists of three parts, as all-optical signal processing unit, optical key sequence generator, and synchronous control unit. In the paper, all-optical signal processing method is key technology using all-optical exclusive disjunction (XOR) gate based on optical cross-gain modulation effect, has advantages of wide dynamic range of input optical signal, simple structure and so on. All-optical XOR gate composed of two semiconductor optical amplifiers (SOA) is a symmetrical structure. By controlling injection current, input signal power, delay and filter bandwidth, the extinction ratio of XOR can be greater than 8dB. Finally, some performance parameters are calculated and the results are analyzed. The simulation and experimental results show that the proposed method can be achieved over 10Gbps optical signal encryption and decryption, which is simple, easy to implement, and error-free diffusion.
The increasing reliance on optical communication networks for high-speed data transmission has amplified concerns regarding secure information exchange in the era of quantum computing. Classical cryptographic protocols such as RSA and ECC, though widely deployed, are vulnerable to attacks from large-scale quantum computers executing Shor’s algorithm. Quantum Key Distribution (QKD) has emerged as a revolutionary cryptographic paradigm that leverages the principles of quantum mechanics to enable theoretically unbreakable key exchange. This paper investigates the integration of QKD into optical communication networks, focusing on protocol design, implementation challenges, and potential scalability. Through scenario-based evaluation, the study highlights the trade-offs between quantum security and practical deployment constraints such as channel loss, photon detector efficiency, and key generation rates. Results from simulated models demonstrate that while QKD can achieve provable security in metropolitan-area networks, long-distance transmission requires advanced techniques such as quantum repeaters and trusted nodes. This work concludes that QKD offers a promising pathway toward quantum-safe communication but necessitates
The increasing reliance on optical communication networks for high-speed data transmission has amplified concerns regarding secure information exchange in the era of quantum computing. Classical cryptographic protocols such as RSA and ECC, though widely deployed, are vulnerable to attacks from large-scale quantum computers executing Shor�s algorithm. Quantum Key Distribution (QKD) has emerged as a revolutionary cryptographic paradigm that leverages the principles of quantum mechanics to enable theoretically unbreakable key exchange. This paper investigates the integration of QKD into optical communication networks, focusing on protocol design, implementation challenges, and potential scalability. Through scenario-based evaluation, the study highlights the trade-offs between quantum security and practical deployment constraints such as channel loss, photon detector efficiency, and key generation rates. Results from simulated models demonstrate that while QKD can achieve provable security in metropolitan-area networks, long-distance transmission requires advanced techniques such as quantum repeaters and trusted nodes. This work concludes that QKD offers a promising pathway toward quantum-safe communication but necessitates advancements in hardware, standardization, and hybrid cryptographic strategies for widespread adoption.
The optical network supporting emerging bandwidth-intensive services has become the cornerstone of the 5G era. However, the development of optical fiber eavesdropping and quantum computing has brought huge security challenges to traditional cryptography. As an effective approach to improving optical layer transmission security, all-optical logic gate encryption has important research significance. This paper proposes a high-speed coherent optical encryption and decryption system based on phase encoding with all-optical logic gates. The system ingeniously designs the phase encoding and decoding scheme between two quadrature phase-shift keying (QPSK) signals, which doubles the encryption and decryption efficiency. In addition, the integration of physical-layer key distribution (PLKD) and physical-layer encryption (PLE) contributes to a reduction in overall system complexity. By adopting real-time signal processing in an all-optical domain, the single-wavelength rate of system security communication can reach 100 Gbps. The system is also applicable to other phase-modulated signals and provides a feasible scheme to enhance transmission security in wavelength division multiplexing (WDM) optical networks featuring high speed, low latency, and high flexibility.
Abstract Exclusive-OR (XOR) operation is a popular technique in optical cryptography. The linear and inverse properties of XOR operation provide a simple way of encryption but in some cases fail to provide strong security. In XOR-based image encryption, each pixel is individually encrypted, therefore secret information can be traced with partial knowledge of the key. In this paper, we describe a simple and practical method to improve the strength and effectiveness of XOR-based encryption. A higher level of security is achieved by implementing a phase retrieval algorithm with XOR operation. Another advantage of the proposed scheme is that the optical XOR operation is demonstrated using incoherent light sources, which make the system compact, speckle free, and cost effective. Also, to overcome the problem of quality degradation while decrypting, quick response code-based ciphertext has been implemented. Both simulation and experimental results are demonstrated as a proof-of-concept.