Dynamic Look-up Table Research Articles

Watermarking for the Secure Transmission of the Key into an Encrypted Image

Ensuring the confidentiality of any data exchanged always presents a great concern for all communication instances. Technically, encryption is the ideal solution for this task. However, this process must deal with the progress of the cryptanalysis that aims to disclose the information exchanged. The risk increases due to the need for a dual transmission that includes the encrypted medium and the decryption key. In a context of chaotic encryption of images, we propose to insert the decryption key into the encrypted image using image watermarking. Thus, only the watermarked encrypted image will be transmitted. Upon reception, the recipient extracts the key and decrypts the image. The cryptosystem proposed is based on an encryption using a dynamic Look-Up Table issued from a chaotic generator. The obtained results prove the efficiency of our method to ensure a secure exchange of images and keys.

EFFICIENT OPERATIONS IN LARGE FINITE FIELDS FOR ELLIPTIC CURVE CRYPTOGRAPHIC

An efficient method to compute the finite field multiplication for Elliptic Curve point multiplication at high speed encryption of the message is presented. The methods of the operations are based on dynamic lookup table and modified Horner rule method. The modified Horner rule method is not only to finite field operations but also to Elliptic curve scalar multiplication in the encryption and decryption. By comparison with using Russian Peasant method and in the new proposed method, one of the advantages of utilizing the proposed algorithm is that in the Elliptic Curve point addition are reduced by a factor of three in GF (2163). Therefore, using the Algorithm 1 running on Intel CPU, computation cost of the multiplication method is above 70% faster than using standard multiplication by Russian Peasant method. Ultimately, the proposed Algorithm 1 for evaluating multiplication can be made regular, simple and suitable for software implementations.

Cryptanalysis of a chaotic image cipher based on plaintext-related permutation and lookup table

In 2017, an efficient chaotic image cipher with dynamic lookup table driven by bit-level permutation strategy (ICDLT) was proposed (Hu et al. Nonlinear Dyn 87:1359–1375). The chaotic cipher adopts a plaintext-related image encryption mechanism as an efficient measure against chosen-plaintext/ciphertext attack. ICDLT is composed of four basic parts: inter-pixel permutation, sequential addition, intra-pixel permutation and diffusion processes, where two kinds of permutation are both related to the plaintext. Although ICDLT is built on complex nonlinear dynamics, we found that it is still vulnerable against chosen-plaintext attack and its individual sub-keys can be recovered using a divide-and-conquer strategy. Benefiting from the essential structure of ICDLT and the intrinsic properties of Latin square, the proposed attack requires only $$ (8 \cdot N^2 +256 + n_c \cdot (2 \cdot N -1))$$ plain images, where $$N^2$$ is the size of the image and $$n_c$$ is the number of cipher images that need to be cracked. Furthermore, we summarize a more general framework which is beneficial for cryptanalyzing a class of plaintext-related image ciphers. Finally, we propose an improved scheme based on the designed plaintext-related XOR encryption (PR-XOR) module to enhance the security of ICDLT. Theoretical analysis and experiments prove that the improved scheme not only maintains the excellent statistical performances of the original one, but also can resist various attacks.

Baptista chaotic cryptosystem based on alternate superior dynamic lookup table

Chaotic cryptosystems are using for securing text data and images over the network. In 1998, M S Baptista suggested a chaotic cryptosystem based on partitioning the visiting interval of chaotic orbits of the logistic map, which attracted much attention. In 2002, K W Wong presented a prompt chaotic cryptosystem based onthe dynamic lookup table using a logistic maptoimprove the security in Baptista type cryptosystem. In 2004, Alvarezet al. [1] found that Wong’s cryptosystem [15] is not resistant tochosen-plaintext and known-plaintext attacks. To improve the security of the dynamic lookup table, weintroduce an alternate dynamic lookup table that will be more secure in context to the existing system.

Directive local color transfer based on dynamic look-up table

Color transfer in image processing usually suffers from misleading color mapping and loss of details. This paper presents a novel directive local color transfer method based on dynamic look-up table (D-DLT) to solve these problems in two steps. First, a directive mapping between the source and the reference image is established based on the salient detection and the color clusters to obtain directive color transfer intention. Then, dynamic look-up tables are created according to the color clusters to preserve the details, which can suppress pseudo contours and avoid detail loss. Subjective and objective assessments are presented to verify the feasibility and the availability of the proposed approach. Experimental results demonstrate that our proposed method has better performance on natural color images than classical color transfer algorithms. Furthermore, the reference image can be extended to color blocks instead of images.

Construction of simulation framework for dynamic analysis of a superconducting magnetic levitation train with flexible car bodies

Magnetic levitation (maglev) trains are eco-friendly and help to transport passengers efficiently and safely. Among two main types of maglev train, the EDS type is more appropriate for ultra-high-speed maglev trains. However, it has disadvantages with regard to vertical and lateral stability induced by external and internal vibrations. To analyze and evaluate the dynamics of ultra-high-speed maglev, we proposed a co-simulation framework for dynamic analysis of an EDS-type maglev with ultra-high-speed and all-flexible car bodies using couple-field analysis. First, electromagnetic forces were calculated with the superconducting coils and magnets using 2D analytic model. And a lookup table for electromagnetic forces was constructed with a large range of levitation from −100 mm to 100 mm and guidance from −50 mm to 50 mm. A rigid car body model was then constructed using a multi-body dynamics program. The flexible car body were modeled using the ANSYS program and converted using rigid body element (RBE2 element). The total simulation framework was constructed using MATLAB Simulink, and the dynamic models, electromagnetic model and lookup table were connected using a cosimulation process. The constructed co-simulation framework was used to investigate the dynamics of a high-speed train under conditions of random irregularity. As results, we found that the first bending and middle layer modes of the flexible car body mutually affected the vibration characteristics of the flexible car body compared to the rigid car body. In addition, flexible car bodies showed greater vibration than rigid car bodies because of elastic modal effects and additional vibration induced by the interactions of the car bodies.

DQ-Voltage Droop Control and Robust Secondary Restoration With Eligibility to Operate During Communication Failure in Autonomous Microgrid

The combination of droop control and communication-based secondary control is eligible to maintain the steady voltage and frequency at the point of common coupling (PCC) together with the property of power sharing between the distributed generators. However, the performance of this combination is threatened by the slow dynamic and communication failure. In this context, an improved droop control is proposed to address the issue of slow dynamic and enhance the power-sharing accuracy in the autonomous microgrid. The droop coefficients are determined through a comprehensive analysis to assess the eigenvalues and plot the loci of the dominant poles. Robust secondary control is subsequently proposed to restore the voltage and frequency to their nominal values with a novel feature that ensures the performance continuity during the communication failure. The key idea of the proposed secondary control relies on utilizing the predictive values of the PCC voltage in the dq-rotating frame using two dynamic lookup tables during communication loss. The proposed control is evidenced by the simulation results in the MATLAB environment.

Budgeting Time for Dynamic Vehicle Routing with Stochastic Customer Requests

Parcel services route vehicles to pick up parcels in the service area. Pickup requests occur dynamically during the day and are unknown before their actual request. Because of working hour restrictions, service vehicles only have a limited time to serve dynamic requests. As a result, not all requests can be confirmed. To achieve an overall high number of confirmed requests, dispatchers have to budget their time effectively by anticipating future requests. To determine the value of a decision, i.e., the expected number of future confirmations given a point of time and remaining free time budget, we present an anticipatory time budgeting heuristic (ATB) drawing on methods of approximate dynamic programming. ATB frequently simulates a problem’s realization to subsequently approximate the values for every vector of point of time and free time budget to achieve an approximation of an optimal decision policy. Since the number of vectors is vast, we introduce the dynamic lookup table (DLT), a general approach adaptively partitioning the vector space to the approximation process. Compared with state-of-the-art benchmark heuristics, ATB allows an effective use of the time budget resulting in anticipatory decision making and high solution quality. Additionally, the DLT significantly strengthens and accelerates the approximation process. The online appendix is available at https://doi.org/10.1287/trsc.2016.0719 .

An efficient chaotic image cipher with dynamic lookup table driven bit-level permutation strategy

Recently, bit-level permutation strategy in chaotic image cryptosystem has been studied extensively due to its pixel value mixing effect. However, the efficiency of such a cryptosystem suffers from its high computational complexity, since more chaotic state variables are required to shuffle the bits rather than pixels. Besides, there exists computational redundancy when ciphering some special images using conventional approaches. To promote the efficiency, a novel bit-level chaotic image cipher based on lookup table is proposed in this paper. Accordingly, a sequential addition operation is introduced before the bit-level permutation for the purpose of reducing the permutation redundancy. Moreover, the diffusion in a cross-reverse manner is also contributed to the speed acceleration. On the other hand, a plaintext-related permutation mechanism is implemented in the lookup table construction to enhance the security of the proposed cryptosystem. Simulation results and analyses show that the proposed scheme is efficient while maintaining high security performance.

Estimation of snow depth from passive microwave brightness temperature data in forest regions of northeast China

Abstract Snow depth is an important factor in water resources management in Northeast China. Forest covers 40% of Northeast China, and the presence of forests influences the accuracy of snow depth retrievals from passive microwave remote sensing data. An optimal iteration method was used to retrieve the forest transmissivities at 18 and 36 GHz based on the snow and forest microwave radiative transfer models and the snow properties measured in field experiments. The transmissivities at 18 and 36 GHz are 0.895 and 0.656 in the horizontal polarization, and 0.821 and 0.615 in the vertical polarization, respectively. Furthermore, the forest transmissivity and snow properties were input into the Microwave Emission Model of Layered Snowpacks (MEMLS) to establish a dynamic look-up table (LUT). Snow depths were retrieved from satellite passive microwave remote sensing data based on the LUT method, and these retrievals were verified by snow depth observations at 103 meteorological stations. The results showed that the bias between the retrieved and measured snow depths is very small, with root mean square errors (RMSEs) of approximately 6 cm in forest regions and 4 cm in non-forest regions. When compared with the existing snow products, the snow depth retrieved in this work presented the highest level of accuracy. The regional snow depth product in China is superior to the GlobSnow and NASA AMSR-E standard SWE products in non-forest regions, whereas the GlobSnow estimate is superior to the regional snow depth product in China and NASA AMSR-E standard SWE product estimates in forest regions. Therefore, we conclude that 1) the influence of forest on snow depth retrieval is important, and the appropriate forest parameters should be considered in the estimation of snow depth from passive microwave brightness temperature data; and 2) the snow depth retrieval algorithm based on the dynamic LUT method proved to be efficient in Northeast China.

Optimal-Behavior-Based Dynamic Calibration of the Automotive Diesel Engine

This paper presents a novel automotive engine management system (EMS) calibration methodology for rapid dynamometer test-bed data collection and mapping I.C. engine controllers with significant dynamic and transient performance requirements. This paper applies the methodology to an industrial state of the art WAVE-RT 1 model of a 1.5 L Turbo EU6.1 Diesel engine acting as a virtual dynamometer based engine. The approach directly yields a feedforward controller in a nonlinear polynomial structure that can be either directly implemented in the EMS or converted into a dynamic or static lookup table format. The methodology is based on multistage black-box modeling and dynamic system optimization. The process can exploit the power of global constrained numerical optimization codes and use system identification techniques with dynamic design of experiments. The objective of the engine controller optimization is to improve the fuel economy while maintaining specified (legislated) limits on emissions and map smoothness for driveability. The key contribution is a novel approach to obtaining a feedforward dynamic calibration controller from the system identification of the computed optimal behavior. Model structure selection techniques are shown to be usefully employed to further improve the accuracy of the system identification and so enhance the control performance of the dynamic controllers. The results indicate that the dynamic calibration methodology leads to a considerably reduced requirement for testing time and an improvement of between 1.9% and 2.6% in fuel economy over extra urban driving cycle without violating the emission constraints compared with current steady-state model-based calibration methods. 1 Ricardo PLC.

Quick and high performance direct power control for multilevel voltage source rectifiers

The paper deals with the control of three-phase voltage source rectifiers (VSRs) with an arbitrary number of voltage levels. By means of an approach borrowed from the “Direct Torque Control” of AC drives, the paper presents an enhanced direct power control (DPC) strategy for VSRs which directly controls both active (P) and reactive (Q) line power by considering the values of their time derivatives. This control strategy can be applied both to the Neutral Point Clamped and to Cascaded H-bridge multilevel converters.In every sampling interval the proposed control technique is able to select the most suitable converter voltage vector to obtain good dynamic response and to maintain P and Q within their respective reference bands. This result is achieved in the different operating conditions by means of a Dynamic Look-Up Table (D-LUT) of the converter voltage vectors, which are ordered on the basis of their influence on P and Q time derivatives. The mentioned D-LUT depends on the instantaneous operating point and is not predetermined.Some significant operating conditions are numerically investigated in order to show the capability of the modified DPC technique to ensure good values of power quality indexes for the grid. Experimental results on a laboratory setup based on a three-level VSR show good accordance with the simulation ones.

FREAC-LUT: A NEW DYNAMIC LOOK-UP TABLE APPROACH TO SECURE CHAOTIC ENCRYPTION

In this work, we present a new chaos-based cryptosystem scheme consisting of a noniterative plaintext transformation and a high dimensionally (K-map) populated dynamic Look-Up Table (LUT) with random access that outperforms the security and speed of previous LUT-based chaotic encryption schemes. Experimental analysis of the proposed scheme reveals excellent statistical properties, naturally extended permanent cycle, and high performance for real-time multimedia communications. Our scheme is one order of magnitude faster than the fastest LUT-based approach in the literature and robust to differential and chosen plaintext attacks.

A NOVEL CHAOTIC IMAGE ENCRYPTION SCHEME BASED ON MAGIC CUBE PERMUTATION AND DYNAMIC LOOK-UP TABLE

This paper puts forward a novel image encryption algorithm that is based on permutation-diffusion architecture. In pixels' permutation stage, algorithm takes full advantage of the idea of magic cube's scrambling. There is only simple cyclic shift operation in each sub-block's permutation, but when the algorithm has disposed the current sub-block, the adjacent sub-blocks will be dealt with, too. In the cyclic shift of each row, stable points will help to decrease the correlation of adjacent pixels. To make encryption procedure uncertain, this paper brings in a parameter named delay-time that is generated by chaotic map. In the diffusion stage, by combining multiple operations and dynamic look-up table together, the proposed algorithm highly increases the uncertainty of the encryption procedure. At last, the experiment results of key space analysis, information entropy analysis, histogram analysis and etc. show that the encryption algorithm has well performance and it can be used in image encryption and transmission.

Keyed hash function based on a dynamic lookup table of functions

In this paper, we present a novel keyed hash function based on a dynamic lookup table of functions. More specifically, we first exploit the piecewise linear chaotic map (PWLCM) with secret keys used for producing four 32-bit initial buffers and then elaborate the lookup table of functions used for selecting composite functions associated with messages. Next, we convert the divided message blocks into ASCII code values, check the equivalent indices and then find the associated composite functions in the lookup table of functions. For each message block, the four buffers are reassigned by the corresponding composite function and then the lookup table of functions is dynamically updated. After all the message blocks are processed, the final 128-bit hash value is obtained by cascading the last reassigned four buffers. Finally, we evaluate our hash function and the results demonstrate that the proposed hash algorithm has good statistical properties, strong collision resistance, high efficiency, and better statistical performance compared with existing chaotic hash functions.

Multiaxial Haar-Like Feature and Compact Cascaded Classifier for Versatile Recognition

A versatile recognition algorithm has been proposed to process image, sound, and 3-D acceleration signals with a common framework at low calculation cost. Firstly, a novel 1-D Haar-like feature is used to roughly extract frequency information from temporal signals. Biaxial and mean-embedded Haar-like features are proposed to extract the standard deviation and the interaxial correlation from 3-D acceleration signals. Secondly, two techniques are proposed to build a compact cascaded classifier. Redundant feature selection (RFS) incorporates the features which are already selected in previous stage classifiers to reduce the calculation cost. A dynamic look-up table (DLUT) is proposed to construct a look-up table-based weak classifier with the smallest possible number of bins. A train loss function is by globally optimized using dynamic programming. The proposed algorithm is tested experimentally on speech/nonspeech classification and human activity recognition. The proposed algorithm yields a speech/nonspeech classification performance comparable to the state-of-art method called MFCC while reducing the calculation cost by 100 times. The algorithm also achieves human activity recognition accuracy of 96.1% with calculation cost reduction of 84% compared with the state-of-art method based on C4.5 decision-tree classifier using the basic statistical features. The proposed algorithm has been employed to build the versatile recognition processor.

Modeling the land surface heat exchange process with the aid of moderate resolution imaging spectroradiomer images

Most ecosystems and crops experience water stress in arid and semiarid areas of the Inner Mongolia grassland, Northern China. Yet the lack of long-term in situ monitoring data hinders the managerial capacity of changing water vapor environment, which is tied with sustaining the grassland in the Inner Mongolia. Environmental remote sensing monitoring and modeling may provide synergistic means of observing changes in thermodynamic balance during drought onset at the grassland surface, providing reliable projections accounting for variations and correlations of water vapor and heat fluxes. It is the aim of this paper to present a series of estimates of latent heat, sensible heat, and net radiation using an innovative first-principle, physics-based model (GEOMOD: GEO-model estimated the land surface heat with MODis data) with the aid of integrated satellite remote sensing and in situ eddy covariance data. Based on the energy balance principle and aerodynamics diffusion theory, the GEOMOD model is featured with MODIS (Moderate Resolution Imaging Spectroradiometer) data with 250 m spatial resolution to collectively reflect the spatial heterogeneity of surface properties, supplement missing data with the neighborhood values across both spatial and temporal domains, estimate the surface roughness height and zero-plane displacement with dynamic look-up table, and implement a fast iterative algorithm to calculate sensible heat. Its analytical framework is designed against overreliance on local micro-meteorological parameters. Practical implementation was assessed in the study area, the Xilin Gol River Basin, a typical grassland environment, Northern China. With 179 days of MODIS data in support of modeling, coincident ground-based observations between 2000 and 2006 were selected for model calibration. The findings indicate that GEOMOD performs reasonably well in modeling the land surface heat exchange process, as demonstrated by a case study of Inner Mongolia.

Dynamic Look-Up-Table-Based Maximum a Posterior Probability Algorithm

In this paper, a Look-Up-Table (LUT) based calculation for implementing log-likelihood ratio (LLR) of the Maximum a Posterior (MAP) decoder is introduced and analysed. In the region of low signal to noise ratio, the analysed performances of turbo coding have been found very satisfying. However, when implementing the MAP turbo decoder, the required calculation for LLR is too complex prohibiting its applications. In order to reduce the complexity a dynamic-LUT based simplification is proposed whereas a static-LUT never converge the expectations, since the limited size and resolution of LUT dramatically degrade the performance. In order to maintain simplicity for a high performance implementation, a dynamic LUT, which has partial resolutions in separate decision regions and being re-calculated for further iterations of decoding, is proposed. One of the most important results obtained is that our proposed dynamic-LUT based MAP algorithm removes "ln(·)" process, which is the natural logarithm in LLR's calculation. Therefore, it reduces high computational complexity in the MAP algorithm with some reasonable performance degradations.

A Dynamic and Differential CMOS Lookup Table with Data Independent Power Consumption for Cryptographic Applications on Chip Cards

Attacks based on a differential power analysis (DPA) are a main threat when designing cryptographic functions for implementation on chip cards. In this paper, a dynamic and differential lookup table (LUT) is presented and evaluated on a case study simulation. The proposed circuit shows a power consumption independent from the input data and can be employed to implement combinatorial functions in cryptographic processors when a high resistance against tampering is required. A typical application is the design of nonlinear functions (for example, substitution boxes) since protecting them with less expensive countermeasures (for example, random masking) implies a significant overhead. In the adopted case study, a 1.02 percent spread in the power consumption has been obtained when parasitic capacitances are taken into account. Moreover, a comparison with a static complementary metal-oxide semiconductor implementation shows an acceptable overhead in terms of area and power consumption.

Improving the security of a dynamic look-up table based chaotic cryptosystem

In this brief, we analyze the cause of vulnerability of the original dynamic look-up table based chaotic encryption scheme in detail, and then propose the corresponding enhancement measures. Theoretical analysis and computer simulation indicate that the modified scheme is more secure than the original one