Abstract We propose and study a new technique for securing fibre data communication. The paper presents a method for optical encryption of information transmitted with a traditional fibre link. The encryption method uses a spatial light modulator which converts light pulses representing original data into pseudo-random patterns. A linear combination of light pulses with pseudo-random patterns provides a required encryption performance. The main element of the encryptor is the spatial light modulator which comprises a matrix of cells selectively transmitting or blocking the light beam depending on the pseudo-random configuration of cells. The encrypted information is transmitted through the optical fibre. The decryption process relies on a computational solving of linear program or greedy pursuit. We present a brief description of the method, theoretical analysis and results of numerical simulation. A physical model concept of the method is also presented.
Abstract We propose and study a new technique for securing fibre data communication. The paper presents a method for optical encryption of information transmitted with a traditional fibre link. The encryption method uses a spatial light modulator which converts light pulses representing original data into pseudo-random patterns. A linear combination of light pulses with pseudo-random patterns provides a required encryption performance. The main element of the encryptor is the spatial light modulator which comprises a matrix of cells selectively transmitting or blocking the light beam depending on the pseudo-random configuration of cells. The encrypted information is transmitted through the optical fibre. The decryption process relies on a computational solving of linear program or greedy pursuit. We present a brief description of the method, theoretical analysis and results of numerical simulation. A physical model concept of the method is also presented.
The growing awareness of the vulnerability of information transmitted on communication systems within the government, military and commercial sectors, has stimulated a number of areas of research within the optical community to design optical hardware encryption systems providing inherent immunity to espionage techniques. This paper describes a hardware optical encryption technique that utilises off the shelf telecommunication equipment and negates the necessity for an independent key distribution system with respect to the data transmission system, as is common with alternative encryption system implementations. This method also lends itself easily to fiber optic or free space communication and is applicable within any optical waveband. The encryption-decryption of the optical signal is achieved through low coherence optical interferometry. This requires the instantaneous processing and analysis of the signal, optically, to retrieve the relevant optical phase information hidden in the transmitted optical noise. This technology allows an authorised user to transmit encrypted information at a high data rate securely, while maintaining opaqueness to an unauthorised observer that data transmission is occurring. As the instantaneous optical field properties of the signals present in the system are essential to the optical encryption - decryption process, the system is inherently protected against electronic recording and advances in computational decryption algorithms. For organisations wishing to protect sensitive data and levels of communication activity these are highly desirable features.
Double random phase encryption (DRPE) is one of the well-known optical encryption techniques, and many techniques with DRPE have been developed for information security. However, most of these techniques may not solve the fundamental security problem caused by using fixed phase masks for DRPE. Therefore, in this paper, we propose a key phase mask updating scheme for DRPE to improve its security, where a spatial light modulator (SLM) is used to implement key phase mask updating. In the proposed scheme, updated key data are obtained by using previous image data and the first phase mask used in encryption. The SLM with the updated key is used as the second phase mask for encryption. We provide a detailed description of the method of encryption and decryption for a DRPE system using the proposed key updating scheme, and simulation results are also shown to verify that the proposed key updating scheme can enhance the security of the original DRPE.
Optical layer attacks on optical fiber communication networks are one of the weakest reinforced areas of the network, allowing attackers to overcome security software or firewalls when proper safeguards are not put into place. Encrypting data using a random phase mask is a simple yet effective way to bolster the data security at the physical layer. Since the interactions of the random phases used for such encryption heavily depend on system properties like data rate, modulation format, distance, degree of phase randomness, laser properties, etc., it is important to determine the optimum operating conditions for different scenarios. In this work, assuming that the transmitter and the receiver have a secret pre-shared key, we present a theoretical study of security in such a system through mutual information analysis. Next, we determine operating conditions which ensure security for 4-PSK, 16-PSK, and 128-QAM formats through numerical simulation. Moreover, we provide an experimental demonstration of the system using 16-QAM modulation. We then use numerical simulation to verify the efficacy of the encryption and study two preventative measures for different modulation formats which will prevent an eavesdropper from obtaining any data. The results demonstrate that the system is secure against a tapping attack if an attacker has no information of the phase modulator and pre-shared key.
An encrypted database interfaced with an ultrafast secure data communication system using spatial-temporal converters is proposed. The original spatial signal is optically encrypted, and the encrypted signal is holographically stored in a storage medium such as photorefractive materials. The spatially encrypted signal is sampled to avoid the overlap of each datum at the receiver. The sampled data are converted into a temporal signal to transmit the information through an optical fiber. At the receiver the temporal signal is converted back into the spatially encrypted signal. Retrieval of the original data can be achieved when the correct phase key is used in the decryption system. We developed an expression for encrypted output and decrypted data. We numerically evaluate the effect of sampling the spatially encrypted signal on the quality of the decrypted data.
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.
A novel way for encrypting optical information based on the principle that rays are retrievable using optical holography is presented.A random modulating plate is added to the Fresnel diffraction field of the original information.The parameters,such as the distance of information propagating and the modulating plate constitute the keys of encryption process.The results of numerical computing and optical experiments show that our method can encrypt and decrypt optical information successfully,being very sensitive to the keys,and have good performance on secrecy and anti-noise.