Hyper-chaos encryption using convolutional masking and model free unmasking

In this paper, during the masking process the encrypted message is convolved and embedded into a Qi hyper-chaotic system characterizing a high disorder degree. The masking scheme was tested using both Qi hyper-chaos and Lorenz chaos and indicated that Qi hyper-chaos based masking can resist attacks of the filtering and power spectrum analysis, while the Lorenz based scheme fails for high amplitude data. To unmask the message at the receiving end, two methods are proposed. In the first method, a model-free synchronizer, i.e. a multivariable higher-order differential feedback controller between the transmitter and receiver is employed to de-convolve the message embedded in the receiving signal. In the second method, no synchronization is required since the message is de-convolved using the information of the estimated derivative.     

Optical hyperspectral data encryption in spectrum domain by using 3D Arnold and gyrator transforms

In this letter, a hyperspectral image encryption algorithm based on 3D Arnold transform and gyrator transform in spectrum domain is proposed. First, the original hyperspectral cube will be scrambled by 3D Arnold transform in the spatial domain. Subsequently, the obtained intermediate data are converted into spectrum domain to create a new spectral image. This new spectral image is decomposed into numerous single pieces and encoded using gyrator transform. The corresponding decrypted hyperspectral cube can be recovered by performing along the reverse direction of the encryption process. Some numerical simulations have been performed to verify the validity and capability of the proposed hyperspectral encryption algorithm.     

使用计算全息进行三维信息加密的方法研究

全息加密技术作为一种特殊的加密方法被广泛应用于信息加密和防伪等领域。在全息加密过程中,光波的波长、记录距离和入射角度等参数用做加密密钥和解密密钥被人们深入研究,但所加密的信息几乎都是二维信息。利用一种基于虚拟光学的对三维信息进行加密的方法,将三维物体的大小作为一个新的密钥被引入安全全息加密算法,其安全性能得到了极大提高;在此基础上提出了对再现三维图像进行客观评价的方法,即修正峰值信噪比法(PSNR,PeakSignal-to-Noise Ratio)。模拟实验证明,计算全息方法(CGH,Computer-Generated Hologram)作为一种对三维信息进行加密的方法是可行的,修正PSNR法对再现三维图像的质量进行定量分析是有效的。     

Autonomous satellite constellation orbit determination using the star sensor and inter-satellite links data

A method of autonomous orbit determination for a satellite constellation using a star sensor combined with inter satellite links(ISLs) is studied.Two types of simulated observation data,Three-Satellite Constellation ISLs and background stellar observations by a CCD star sensor,are first produced.Based on these data,an observation equation is built for the constellation joint autonomous orbit determination,in which the simulations are run.The accuracy of this method with different orbital determination model...     

A scheme for data encryption and transmission using temporal correlation-based spectral switches

We present a method for data encoding in terms of spectral shifts in the source spectra. The spectral switching of polychromatic light due to temporal correlation, around the intensity minima in a Michelson Interferometer (MI) has been utilized for this purpose. The potential application of the encoding method for free space communication is described in detail. The advantages of this method are compared with the proposed schemes of data communication using spectral switches. The experimental constraints of this method are also discussed.     

Universal quantum circuit evaluation on encrypted data using probabilistic quantum homomorphic encryption scheme

Homomorphic encryption has giant advantages in the protection of privacy information. In this paper, we present a new kind of probabilistic quantum homomorphic encryption scheme for the universal quantum circuit evaluation. Firstly,the pre-shared non-maximally entangled states are utilized as auxiliary resources, which lower the requirements of the quantum channel, to correct the errors in non-Clifford gate evaluation. By using the set synthesized by Clifford gates and T gates, it is feasible to perform the arbitrary quantum computation on the encrypted data. Secondly, our scheme is different from the previous scheme described by the quantum homomorphic encryption algorithm. From the perspective of application, a two-party probabilistic quantum homomorphic encryption scheme is proposed. It is clear what the computation and operation that the client and the server need to perform respectively, as well as the permission to access the data. Finally, the security of probabilistic quantum homomorphic encryption scheme is analyzed in detail. It demonstrates that the scheme has favorable security in three aspects, including privacy data, evaluated data and encryption and decryption keys.     

A fast image encryption method by using chaotic 3D cat maps

An image encryption method using a chaotic 3D cat map is presented in this paper. The process of the proposed algorithm contains the simultaneous operations of pixels’ locations permutation and pixels’ values substitution at every iterative step of the chaotic map, which making the forward and reverse encryption needs only one traverse of the image pixels. Moreover, a perturbation is introduced to eliminate the undesirable finite precision effect of computer in realization. The main advantages of such a secure method are the simplicity and efficiency. Both simulations and analysis show the proposed algorithm can produce a large key space and resist the common existing cipher attacks. These good cryptographic properties make it suitable for image applications.     

Security enhancement for double-random phase encryption using orthogonally encoded image and electronically synthesized key data

We propose a security-enhanced double-random phase encryption(DRPE) scheme using orthogonally encoded image and electronically synthesized key data to cope with the security problem of DRPE technique caused by fixed double-random phase masks for encryption. In the proposed scheme, we adopt the electronically synthesized key to frequently update the phase mask using a spatial light modulator, and also employ the orthogonal encoding technique to encode the image and electronically synthesized key data, which can enhance the security of both data. We provide detailed procedures for encryption and decryption of the proposed scheme, and provide the simulation results to show the encryption effects of the proposed scheme.     

Rapid 3D surface profile measurement of industrial parts using two-level structured light patterns

This paper aims to present a rapid 3D shape measurement system based on novel monochromatic structured light patterns. The system consists of projectors shooting the fringe patterns onto the inspected parts and cameras recording the corresponding distorted images. Using the two-level fringe patterns, the correspondence between the projector image and camera image can be established with sub-pixel accuracy. The two-level pattern is based on three spatiotemporal binary stripes, in which the value of the stripe boundary (first-level coding) is determined by the two adjacent stripes patterns over time and the codeword of the strip boundary (second-level coding) depends on its values and neighbor boundary values in space. The proposed pattern is robust to ambience light variation and part texture. Moreover, the occlusion can be overcome and high density measurement can be achieved. Experiments with different 3D parts are conducted to evaluate the robustness and accuracy of the inspection system using the two-level patterns. The results show that the system has desired properties of high accuracy, high density, rapid acquisition, and robustness, which are essential for industrial application.     

网络信息安全中DES数据加密技术研究

网络信息安全关系到数据存储安全和数据通信安全,为了提高网络信息安全管理能力,需要进行数据优化加密设计,提出一种基于前向纠错编码的DES数据公钥加密技术,采用Gram-Schmidt正交化向量量化方法构建DES数据的Turbo码模型,通过三次重传机制产生密文序列,对密文序列进行前向纠错编码设计,结合差分演化方法进行频数检验,实现网络信息安全中DES数据加密密钥构造,选择二进制编码的公钥加密方案有效抵抗密文攻击。仿真结果表明,采用该加密技术进行DES数据加密的抗攻击能力较强,密钥置乱性较好,具有很高的安全性和可行性。     

Physical properties and microstructures of nanocrystals reinforced ice laser 3D print layer

Rapid prototyping based on laser alloying by the pre-placed mixed powders has been used to produce the nanocrystals reinforced three-dimensional layer in this study. Such a layer was fabricated on a TC17 titanium alloy by laser rapid prototyping (LRP) of the Co–Sb–TiB₂ mixed powders in ice. Scanning electron microscope (SEM) and high resolution transmission electron microscopy (HRTEM) test results indicated that the ice addition was able to decrease the maximum temperature of molten pool during the LRP process, favoring the formation of nanocrystals; growth of such nanocrystals was retarded by the surrounded amorphous in a certain extent, favoring the formations of ultrafine nanoparticles (UN), and the twin crystals and the high-angle grain boundaries were also observed; differential thermal analysis (DTA) test was used to explain the physical properties and formation mechanism of amorphous–nanocrystals, and also the relationship between the amorphous and nanocrystalline phases in such a LRP layer.     

A 3D image encryption technique using computer-generated integral imaging and cellular automata transform

A novel three-dimensional (3D) image encryption approach by using the computer-generated integral imaging and cellular automata transform (CAT) is proposed, in which, the two-dimensional (2D) elemental image array (EIA) digitally recorded by light rays coming from the 3D image is mapped inversely through the virtual pinhole array according to the ray-tracing theory. Next, the encrypted image is generated by using the 2D CAT scrambling transform for the 2D EIA. The reconstructed process is carried out by using the modified computational integral-imaging reconstruction (CIIR) technique; the depth-dependent plane images are reconstructed on the output plane. The reconstructed 3D image quality of the proposed scheme can be greatly improved, because the proposed encryption scheme carries out in a computer which can avoid the light diffraction caused by optical device CIIR, and solves blur problem caused by CIIR by using the pixel-averaging algorithm. Furthermore, the CAT-based encryption algorithm is an error-free encryption method; CAT as an orthogonal transformation offers considerable simplicity in the calculation of the transform coefficient, that is, it can improve the quality of the reconstructed image by reducing energy loss compared with the traditional complicated transform process. To show the effectiveness of the proposed scheme, we perform computational experiments. Experimental results show that the proposed scheme outperforms conventional encryption methods.     

Selective phase masking to reduce material saturation in holographic data storage systems

Emerging networks and applications require enormous data storage. Holographic techniques promise high-capacity storage, given resolution of a few remaining technical issues. In this paper, we propose a technique to overcome one such issue: mitigation of large magnitude peaks in the stored image that cause material saturation resulting in readout errors. We consider the use of ternary data symbols, with modulation in amplitude and phase, and use a phase mask during the encoding stage to reduce the probability of large peaks arising in the stored Fourier domain image. An appropriate mask is selected from a predefined set of pseudo-random masks by computing the Fourier transform of the raw data array as well as the data array multiplied by each mask. The data array or masked array with the lowest Fourier domain peak values is recorded. On readout, the recorded array is multiplied by the mask used during recording to recover the original data array. Simulations are presented that demonstrate the benefit of this approach, and provide insight into the appropriate number of phase masks to use in high capacity holographic data storage systems.     

Analysis of machining characteristics in electrochemical etching using laser masking

Electrochemical etching using laser masking (EELM), which is a combination of laser beam irradiation for masking and electrochemical etching, allows the micro fabrication of stainless steel without photolithography technology. The EELM process can produce various micro patterns and multilayered structures. In this study, the machining characteristics of EELM were investigated. Changes in characteristics of recast layer formation and the protective effect of the recast layer according to the laser masking conditions and electrochemical etching conditions were investigated by field emission scanning electron microscopy (FE-SEM), focused ion beam (FIB) and X-ray photoelectron spectroscopy (XPS). The oxidized recast layer with a thickness of 500 nm was verified to yield a superior protective effect during electrochemical etching and good form accuracy. Finally, micro patterns and structures were fabricated by EELM.     

Advantages of using multiple-echo image combination and asymmetric triangular phase masking in magnetic resonance venography at 3 T

The present work explores the possibility of localizing veins with magnetic resonance venography using susceptibility weighted imaging. It also seeks new approaches, directed by the spatial specificity of activated brain regions, that have sufficient precision for practical use in functional MRI studies. A 3D flow compensated multiple gradient echo sequence, featuring optimized T2* weighting within a reasonable time of acquisition (11 min) and a small voxel size (0.5x0.5x1 mm3), was used to acquire MR images at 3 T. Post-processing consisted of homodyne filtering, linear phase scaling and magnitude masking prior to minimum intensity projection (mIP). The multiple echo approach provided a satisfactory (48+/-7%) increase in signal-to-noise ratio with respect to conventional methods. Specific features of the blood oxygenation level-dependent phase effect were simulated and used for designing and exploring different phase masking methods in relation to vessel morphology and MRI voxel geometry. As with simulations, the best results were obtained with an asymmetric triangular phase masking, featuring an improved venographic contrast without any increase in the full-width at half-maximum. The multiple echo approach provided satisfactory vessel localization capacity by using asymmetric triangular phase masking and a 4-mm-thick mIP. The venographic contrast obtained enabled the detection of vessels with diameter down to approximately 500 microm, suggesting the applicability of the proposed method as an additional technique in fMRI studies.     

Optical encryption using phase-shifting interferometry in a joint transform correlator

We propose an optical encryption technique where the encrypted field and the decrypting key are obtained by three-step phase-shifting interferometry and registered as digital Fresnel holograms in a joint transform correlator architecture. Decryption can be achieved by digital or optical means. The technique allows the complete process to be achieved at high speed and data to be transfered via digital communication channels. Experimental implementation is performed in a system based on a programmable liquid-crystal TV display working in pure phase mode to represent the input data and to introduce the required phase shifts. A CCD is used to register the output data.     

Geodetic VLBI data analysis using VLBI3 software

Summary VLBI (Very Long Baseline Interferometry) geodetic data have been analysed. Baseline, lengths of several thousands kilometers and their time rates have been estimated from a subset of data, spanning three years, of the IRIS project and using VLBI3 software. A weighted-least-squares estimation has been carried out with thea priori standard deviations of the data modified to account for systematic biases due to mismodelling of the clocks and atmosphere. Comparisons with independent analysis show an agreement to the cm level or better both in baseline lengths and rates.     

Evidence for spatial tuning in informational masking using the probe-signal method

Auditory spatial attention is one mechanism that may contribute to the ability to identify one sound source in a multi-source environment. The role of auditory spatial attention in a multi-source environment was investigated using the probe-signal method. The experiment took place in a quiet room with seven speakers arranged in a semi-circle in front of the listener. The speakers were placed at 30-degree intervals at a distance of 5 ft from the listener. The signal was comprised of eight contiguous, 60-ms pure-tone bursts arranged in either a rising or falling frequency pattern. Masker components were also comprised of eight contiguous pure-tone bursts but with durations that varied randomly from 20 to 100 ms. The six maskers were played with the signal and were constructed in order to result in informational rather than energetic masking. The frequency of each masker component was chosen randomly on each burst from a narrow frequency band, independent from the signal frequency band. The task was 1I-2AFC fixed-level identification with response time measurement. The listener was instructed to focus attention on a specified speaker (expected location) for a block of trials. Accuracy and response time were compared across two conditions: (1) signal presented at the expected location and (2) signal presented at an unexpected location. Results indicate a significant increase in accuracy and faster response time when the signal was presented at the expected location as compared to an unexpected location. These results suggest that auditory spatial attention plays an important role in multi-source listening, especially when the listening environment is complex and uncertain.     

Physical layer security using beamforming techniques for 5G and beyond networks: A systematic review

It has been predicted that by the year 2030, 5G and beyond 5G (B5G) networks are expected to provide hundreds of trillions of gigabytes of data for various emerging applications such as augmented, mixed, and virtual reality (AR/MR/VR), wireless computer-brain interfaces (WCBI), connected robotics and autonomous systems. Most of these applications share data with each other using an open channel, i.e., the Internet. The open and broadcast nature of wireless channel makes the communication susceptible to various types of attacks (e.g., eavesdropping, jamming). Thus, there is a strong requirement to enhance the secrecy of wireless channel to maintain the privacy and confidentiality of transmitted data. Physical layer security (PLS) has evolved as a novel concept and robust alternative to cryptography-based techniques, which have a number of drawbacks and practical issues for 5G and beyond networks. Beamforming is an energy-efficient PLS technique, that involves steering of the transmitted signal in a particular direction, while considering that an intruding user attempts to decode the transmitted data. Motivated from these points, this article summarizes various beamforming based PLS techniques for secure data transmission in 5G and B5G networks. We investigate the eight most promising techniques for beamforming in PLS: Non-Orthogonal Multiple Access (NOMA), Full-Duplex Networks, Massive Multiple-Input Multiple-Output (MIMO), Cognitive Radio (CR) Network, Relay Network, Simultaneous Wireless Information and Power Transfer (SWIPT), UAV Communication Networks and Space Information Networks, and Heterogeneous Networks. Moreover, various physical layer threats and countermeasures associated with 5G and B5G networks are subsequently covered. Lastly, we provide insights to the readers about constraints and challenges for the usage of beamforming-based PLS techniques in various upcoming future applications.     

Multiple-image encryption using phase retrieve algorithm and intermodulation in Fourier domain

We propose a novel method for multiple-image encryption using a phase retrieve algorithm and intermodulation in the Fourier domain. All plaintexts to be encoded are first encoded separately into a phase-only function in the Fourier domain with the help of the phase retrieve algorithm. Then these phase-only functions serve mutually as the second encryption keys to be intermodulated into a single image. As a result, all plaintexts can be extracted from the ciphertext without any cross-talk and the encrypted capacity is nearly unlimited. The feasibility and effectiveness of the proposed method are demonstrated by numerical results.