The rapid globalization of the digital ecosystem has elevated information security to a critical concern in modern society. Optical encryption offers an effective approach for enhancing information protection; however, existing optical encryption strategies are unable to reliably recover encrypted information following free-space transmission. To address this challenge, we propose a novel protocol named the optical coherence engineering encryption protocol (OCE-Encryption Protocol). By jointly manipulating the optical coherence structure and introducing astigmatic phase modulation, the protocol generates a spectral intensity ciphertext capable of secure free-space transmission. At the receiver, the original information can be accurately reconstructed by measuring the optical coherence structure of the received ciphertext and applying the correct decryption key. Furthermore, the proposed protocol demonstrates strong resilience to transmission channel disturbances. We hope that optical coherence engineering can expand the functional boundaries of existing optical encryption protocols and provide a pathway toward next-generation secure optical communication systems.
The rapid globalization of the digital ecosystem has elevated information security to a critical concern in modern society. Optical encryption offers an effective approach for enhancing information protection; however, existing optical encryption strategies are unable to reliably recover encrypted information following free-space transmission. To address this challenge, we propose a novel protocol named the optical coherence engineering encryption protocol (OCE-Encryption Protocol). By jointly manipulating the optical coherence structure and introducing astigmatic phase modulation, the protocol generates a spectral intensity ciphertext capable of secure free-space transmission. At the receiver, the original information can be accurately reconstructed by measuring the optical coherence structure of the received ciphertext and applying the correct decryption key. Furthermore, the proposed protocol demonstrates strong resilience to transmission channel disturbances. We hope that optical coherence engineering can expand the functional boundaries of existing optical encryption protocols and provide a pathway toward next-generation secure optical communication systems.
In the modern landscape of the internet, the secure storage and transmission of information are key objectives. Optical encryption is a long-standing method for improving information security; however, existing optical encryption strategies are unable to reliably recover encrypted information following free-space transmission. We propose an encryption protocol that utilizes the statistical features of random light fields to overcome the limitations of existing approaches. This protocol entails continuously refreshing the white complex noise to generate a colored complex noise set that carries encrypted information. Users can recover information by determining the spatial coherence structure of the ciphertext at the receiving end. Furthermore, the proposed protocol exhibits resilience against external noise attacks within the transmission channel, and the protocol’s unlimited key set makes it resistant to computer brute-force attacks. We hope that optical coherence engineering will extend the capabilities of existing optical encryption protocols, paving the way for future optical encryption technology.
Abstract We propose a comprehensive and efficient optical-cryptographic encryption scheme to improve the security of vulnerable optical encryption systems. Based on cryptography theory, we increase data protection using diffusion-confusion processes acting in the input and output of the optical encryption scheme. The new enhanced ciphertext has attributes of a one-way function that is easy to achieve but almost impossible to revert without the correct random phase masks used for diffusion-confusion operations. Despite the straightforward design, combining optical, cryptographic, and chaos methods increases the number of encryption–decryption keys raising two significant concerns. First, the management and transmission of several keys carry a high storage footprint, and second, it impairs the optical high-speed information processing capability. We overcome these two drawbacks by applying a new optical keystream synthesizer based on the stochastic speckle nature and a maximum entropy constraint in a forward–backward propagation algorithm. This new approach quickly replicates the necessary keystream in the encryption–decryption stations offering higher security and efficiency than other reported systems. We validate the feasibility of this proposal by synthesizing an experimental keystream and performing 24-bit data encryption–decryption. Then, we verify the security improvement of two vulnerable cryptosystems and their robustness against cryptanalysis attacks. Finally, we perform experimental encryption–decryption.
Abstract Optical encryption strategies utilizing fully coherent light have been widely explored but often face challenges such as speckle noise and beam instabilities. In this work, we introduce a novel protocol for multi-channel optical information encoding and encryption using vectorial spatial coherence engineering of a partially coherent light beam. By characterizing the beam’s spatial coherence structure with a 2×2 2 × 2 coherence matrix, we demonstrate independent control over the three components of the coherence Stokes vector. This allows for three-channel optical information encoding and encryption, with applications in color image representation. Unlike existing methods based on fully coherent light modulations, our approach utilizes a two-point dependent coherence Stokes vector, proving resilient to random noise in experimental scenarios. Our findings provide a robust foundation for higher-dimensional optical encoding and encryption, addressing limitations associated with partially coherent light in complex environments.
Optical layer attacks on communication networks are one of the weakest reinforced areas of the network, allowing attackers to overcome security when proper safeguards are not put into place. Here, we present our solution or Quantum Encryption in Phase Space (QEPS), a physical layer encryption method to secure data over the optical fiber, based on our novel round-trip Coherent-based Two-Field Quantum Key Distribution (CTF-QKD) scheme. We perform a theoretical study through simulation and provide an experimental demonstration. The same encryption is used for QEPS as CTF-QKD but achieved through a pre-shared key and one-directional transmission design. QEPS is uniquely different from traditional technology where encryption is performed at the optical domain with coherent states by applying a quantum phase-shifting operator. The pre-shared secret is used to seed a deterministic random number generator and control the phase modulator at the transmitter for encryption and at the receiver for decryption. Using commercially available simulation software, we study two preventative measures for different modulation formats which will prevent an eavesdropper from obtaining any data. QEPS demonstrates that it is secure against tapping attacks when attackers have no information of the phase modulator and pre-shared key. Finally, an experiment with commercial components demonstrates QEPS system integrability.
In conventional optical communication systems, the transmission signals are regular digital signals. Due to the openness of optical fiber networks, it is rather easy for eavesdroppers to obtain the transmission signals from the public fiber-link and then intercept the message directly. To address this crucial security challenge, in this work we propose a high-speed secure optical communication system in virtue of physical random temporal encryption based on private physical random phase modulation and phase-to-intensity conversion. The proposed physical random temporal encryption is performed by a module composed of a phase modulator (PM) and a chirped fiber Bragg grating (CFBG), and the corresponding decryption is achieved with a similar module composed of an inverse-phase driven PM and an oppositedispersion CFBG. By distributing a constant-amplitude random-phase signal to the local semiconductor lasers deployed in the encryption module and decryption module, a pair of synchronized physical random PM driving signals that are not exchanged on public link can be independently generated, which guarantees the receiver end can correctly decrypt the original transmission message. Our numerical results demonstrate that with the proposed encryption scheme, the regular transmission signal is encrypted as a noise-like signal that can greatly enhance the security of message, and moreover, based on the private synchronized physical random phase modulation, the privacy of encryption and decryption are guaranteed, which prevents the eavesdroppers from intercepting transmission message. This work provides a promising strategy for the implement of high-speed high-security physical-layer optical communication.
Communication technology is the cornerstone of the modern information society. Among them, optical communication technology, with its advantages of high bandwidth, low loss, and anti-interference, is gradually becoming the core transmission method of future information. However, optical communication systems still have security risks, such as signal eavesdropping, data tampering, and channel interference. To address these challenges, an optical communication encryption technology based on CPolSK modulation is proposed. The results show that this technology has a 16% higher anti-side-channel attack performance than traditional modulation at a lower signal-to-noise ratio, and in the free-space optical communication (FSO) scenario, the decoding accuracy of encrypted image information transmitted through optical communication exceeds 95%.