Finite Precision Computations

La teoría del caos estudia el comportamiento errático de los sistemas dinámicos no lineales, altamente sensibles a las condiciones iniciales (efecto mariposa). Su estudio se remonta a los 1950s, en que el meteorólogo Edward N. Lorenz intentó hacer un modelo de los fenómenos atmosféricos . Generador recursivo múltiple: x n = x n-1 + 12 x n-2 + 0.5 mód 1. Generador congruencial lineal. Como remediar los problemas de los sistemas dinámicos discretos: con pseudocáos Perturbación de los bits menos significativos de los números generados. Rotación de los bits de los números generados. Realización dinámica de los anteriores. Variación dinámica del valor de los parámetros.

This paper describes how to determine the parameter values of the chaotic Lorenz system from one of its variables waveform. The geometrical properties of the system are used firstly to reduce the parameter search space. Then, a synchronization-based approach, with the help of the same geometrical properties as coincidence criteria, is implemented to determine the parameter values with the wanted accuracy. The method is not affected by a moderate amount of noise in the waveform. As way of example of its effectiveness, the method is applied to figure out directly from the ciphertext the secret keys of two-channel chaotic cryptosystems using the variable z as a synchronization signal, based on the ultimate state projective chaos synchronization.

This paper illustrates a general framework in which a neural network application can be easily integrated and proposes a traffic forecasting approach that uses neural networks based on graphs. Neural networks based on graphs have the advantage of capturing spatial–temporal
characteristics that cannot be captured by other types of neural networks. This is due to entries that are graphs that, by their nature, include, besides a certain topology (the spatial characteristic),
connections between nodes that model the costs (traffic load, speed, and road length) of the roads between nodes that can vary over time (the temporal characteristic). As a result, a prediction in a node
influences the prediction from adjacent nodes, and, globally, the prediction has more precision. On the other hand, an adequate neural network leads to a good prediction, but its complexity can be higher.
A recurrent neural network like LSTM is suitable for making predictions. A reduction in complexity can be achieved by choosing a relatively small number (usually determined by experiments) of hidden levels. The use of graphs as inputs to the neural network and the choice of a recurrent neural
network combined lead to good accuracy in traffic prediction with a low enough implementation effort that it can be accomplished on microcontrollers with relatively limited resources. The proposed
method minimizes the communication network (between vehicles and database servers) load and represents a reasonable trade-off between the communication network load and forecasting accuracy.
Traffic prediction leads to less-congested routes and, therefore, to a reduction in energy consumption.
The traffic is forecasted using an LSTM neural network with a regression layer. The inputs of the neural network are sequences—obtained from a graph that represents the road network—at specific moments in time that are read from traffic sensors or the outputs of the neural network
(forecasting sequences). The input sequences can be filtered to improve the forecasting accuracy. This general framework is based on the Contiki IoT operating system, which ensures support for wireless communication and the efficient implementation of processes in a resource-constrained system, and it is particularized to implement a graph neural network. Two cases are studied: one case in which the traffic sensors are periodically read and another case in which the traffic sensors are read when
their values’ changes are detected. A comparison between the cases is made, and the influence of filtering is evaluated. The obtained accuracy is very good and is very close to the accuracy obtained in an infinite precision simulation, the computation time is low enough, and the system can work in real time.

The symbolic time series generated by a unimodal chaotic map starting from any initial condition creates a binary sequence that contains information about the initial condition. A binary sequence of a given length generated this way has a one-toone correspondence with a given range of the input signal. This can be used to construct analogue to digital converters (ADC). However, in actual circuit realizations, component imperfections and ambient noise result in deviations in the map function from the ideal, which, in turn, can cause significant error in signal measurement. In this paper, we propose ways of circumventing these problems through an algorithmic procedure that takes into account the non-idealities. The most common form of nonideality-reduction in the height of the map function-alters the partitions that correspond to each symbolic sequence. We show that it is possible to define the partitions correctly if the height of the map function is known. We also propose a method to estimate this height from the symbolic sequence obtained. We demonstrate the efficacy of the proposed algorithm with simulation as well as experiment. With this development, practical ADCs utilizing chaotic dynamics may become reality.

The purpose of this paper is to investigate the logistic model using Ishikawa iterative procedure through time series and Lyapunov exponent analysis. It is observed that for certain choices there is an appreciable growth in the stability of the model even for the higher values of the control parameter.

Lightweight cryptographic algorithms must develop to ensure the confidentiality and integrity of the data in resource-constrained devices. Keys are vital to every cryptography algorithm because they provide randomness, complexity, unexpected nature, and robustness. A light encryption device (LED) is considered a lighter version of advanced encryption standard (AES), but it is vulnerable to related key attacks due to using the same key during the whole encryption process. This paper presents a hybrid chaotic key generator (HCKG) based on 3D Lorenz, and 2D Henon maps to generate a highly randomized key that combines with the LED to provide a high level of secure encryption on resource-constrained devices. We modified the HCKG every four rounds via simple operations to get the subkeys and XORed it with the state to increase the complexity of the ciphertext. Moreover, the HCKG with subkeys allows us to decrease the total number of LED rounds from 32 to 24 to minimize the calculation cost while maintaining a high level of security. National Institute of Science and Technology (NIST) test suite proves that the proposed LED-HCKG demonstrates a high-performance increase by nearly 0.3283 higher than LED concerning data integrity and secrecy.

Recently, the use of nonlinear discrete dynamic systems to construct cryptographic applications has received a great deal of attention. The encryption applications are intrinsically related to the chaotic behavior of the system, by properties such as sensitivity to the initial conditions, ergodicity and mixing. Obviously, the security of these applications is induced by wide ranges of the control parameters for which the used dynamic system has a chaotic behavior. A map that is preferred for the simplicity and performances offered in applications aimed to protect the information is represented by the tent map. The disadvantage of its use is related to the fact that it shows a chaotic behavior only for a very small set of control parameter values. To attenuate this disadvantage, we propose a new method based on the composition of two tent maps. The viability of the proposed method is mathematically validated by the analysis of Lyapunov exponents and chaotic orbits generated by the on...

This paper analyzes the use of the logistic map for cryptographic applications. The most important characteristics of the logistic map are shown in order to prove the inconvenience of considering this map in the design of new chaotic cryptosystems.

In recent years many chaotic cryptosystems based on Baptista's seminal work have been proposed. We analyze the security of two of the newest and most interesting ones, which use a dynamically updated look-up table and also work as stream ciphers. We provide different attack techniques to recover the keystream used by the algorithms. The knowledge of this keystream provides the attacker with the same information as the key and thus the security is broken. We also show that the dependence on the plaintext, and not on the key, of the look-up table updating mechanism facilitates cryptanalysis.

We propose a new audio signal encryption scheme based on the chaotic Hénon map. The scheme mainly comprises two phases: one is the preprocessing stage where the audio signal is transformed into a data by the lifting wavelet scheme and the other in which the transformed data is encrypted by chaotic data set and hyperbolic functions. Furthermore, we use dynamic keys and consider the key space size to be large enough to resist any kind of cryptographic attacks. A statistical investigation is also made to test the security and the efficiency of the proposed scheme.

There are many algorithms used with different purposes in the area of cryptography. Amongst these, Genetic Algorithms have been used, particularly in the cryptanalysis of block ciphers. Interest in the use of and research on such algorithms has increased lately, with a special focus on the analysis and improvement of the properties and characteristics of these algorithms. In this way, the present work focuses on studying the fitness functions involved in Genetic Algorithms. First, a methodology was proposed to verify that the closeness to 1 of some fitness functions’ values that use decimal distance implies decimal closeness to the key. On the other hand, the foundation of a theory is developed in order to characterize such fitness functions and determine, a priori, if one method is more effective than another in the attack to block ciphers using Genetic Algorithms.

In the era of a global village, a huge amount of people are connected to the web through their PC, mobile and any type of communication tool for communication purposes, hence we require a safe approach that provides security and protection from unauthorized clients and misuses of data and information. Cryptography is a widespread technique to guarantee security for the internet-based communication framework. Many cipher technique have developed but the rail Fence is the simplest and amusing cryptographic algorithm until now. In this technique, the plain text is organized as crosswise and read it from top to the bottom row produces the cipher text. An inadequate quantity of keys is its weakness. This paper redesigned the current rail fence by applying the three basic phases: substitution phase once and transposition phases uses twice. The proposed technique ensures that the resultant cipher text is a fusion of various symbols precise by a chart. The proposed algorithm eliminates the ...

The binary patterns of the shares, however, have no visual meaning and hinder the objectives of visual cryptography. By improving the intensity transformation in Myodo’s method, authors have proposed a method to generate high quality share images with high speed from which a secret image can be reconstructed with apparently higher quality than myodo’s method. In this paper, we review the method and evaluate its performance Based on the blue-noise dithering principles, the proposed method utilizes the void and cluster algorithm to encode a secret binary image into halftone images carrying significant visual information.

A new probabilistic symmetric-key encryption scheme based on chaotic-classified properties of Hopfield neural networks is described. In an overstoraged Hopfield Neural Network (OHNN) the phenomenon of chaotic-attractors is well documented and messages in the attraction domain of an attractor are unpredictably related to each other. By performing permutation operations on the neural synaptic matrix, several interesting chaotic-classified properties of OHNN

Security of multimedia data is a major concern due to its widespread transmission over various communication channels. Hence design and study of good image encryption schemes has become a major research topic. During the last few decades, there has been a increasing in chaos-based cryptography. This paper proposes an attack on a recently proposed chaos based image encryption scheme. The cryptosystem under study proceed by first shuffling the original image to disturb the arrangement of pixels by applying a chaotic map several times. Second, a keystream is generated using Chen's chaotic system to mix it with the shuffled pixels to finally obtain the cipher image. A chosen ciphertext attack can be done to recover the system without any knowledge of the key. It simply demands two pairs of plaintext-ciphertext to completely break the cryptosystem.

In this paper, we have discussed the dynamics of 1-D Mouse map which is also known as Gaussian Iterated map or simply Gauss map and analyzed their chaotic behaviors in several senses. We have mainly focused on several chaotic dynamics like Orbit Analysis, Time Series Analysis, Lyapunov Exponent Analysis, Sensitivity to Initial Conditions, Bifurcation Diagram, Cobweb Diagram, Histogram, Trajectories and Sensitivity to Numerical Inaccuracies of this map. Finally we have shown its graphical analysis and found that this map is chaotic in the mentioned senses. We have performed all graphical activities by using Mathematica and MATLAB.

In this paper, a fast encryption scheme based on chaotic maps is proposed. Firstly the dynamical 8×8 S-box is<br> produced by using logistic map and 2D standard map. Secondly a sequence of pseudo-random bytes is generated by using<br> 2D chaotic cat map to index the entries of the S-box. The output bytes from the S-box are XOR-ed with the plaintext to<br> produce the ciphertext. The results of simulations show that this encryption scheme is secure and fast enough to be used in<br> real-time image encryption applications.

This Letter describes how to determine the parameter of the chaotic Lorenz system used in a two-channel cryptosystem. First the geometrical properties of the Lorenz system are used to reduce the parameter search space. Second the parameters are exactly determined-directly from the ciphertext-through the minimization of the average jamming noise power created by the encryption process.

This paper analyzes and evaluates the performance of neural network testing using microcontrollers. The finite precision of microcontrollers registers and the computation time were considered for evaluation. The paper illustrates a general framework in which a neural network application can be easily integrated. This framework is based on Contiki IoT operating system that ensure support for wireless communication and efficient implementation of processes in a resource constrained system. As a practical example, a human activity recognition system, based on Long Short-Term Memory recurrent neural network, was implemented, and evaluated using a modified evaluation board from Analog Devices. The obtained system accuracy is very good, very close to the accuracy obtained in infinite precision simulation, the computation time is low enough and the system works in real time.

The frequency of occurrence of ordinal patterns in an observed (or measured) times series can be used to identify equivalent dynamical system. We demonstrate this approach for system identification and parameter estimation for dynamics that can (at least approximately) be described by one-dimensional iterated maps.

A technique for the recursive inversion of matrices and matrix functions is presented. The proposed method can be modelled as a discrete nonlinear dynamic system. Convergence, stability and robustness properties are discussed and eventually verified through various numerical experiments.

This paper analyzes and evaluates the performance of neural network testing using microcontrollers. The finite precision of microcontrollers registers and the computation time were considered for evaluation. The paper illustrates a general framework in which a neural network application can be easily integrated. This framework is based on Contiki IoT operating system that ensure support for wireless communication and efficient implementation of processes in a resource constrained system. As a practical example, a human activity recognition system, based on Long Short-Term Memory recurrent neural network, was implemented, and evaluated using a modified evaluation board from Analog Devices. The obtained system accuracy is very good, very close to the accuracy obtained in infinite precision simulation, the computation time is low enough and the system works in real time.

This paper presents a medical image cipher with hierarchical diffusion and non-sequential encryption mechanism. An improved permutation approach is developed, which can contribute to not only image shuffling but also lightweight pixel modification at the same time. Therefore, diffusion property of the proposed scheme is achieved from both the permutation and diffusion phases, and hierarchical diffusion effect is thus obtained. Besides, non-sequential visiting mechanism is developed to encrypt the plain pixels in secret order; in other words, pixel visiting order is exploited as extra encryption factor in addition to the traditional pixel location and gray value. With hyperchaotic Lorenz system employed as key stream generator, a complete image encryption scheme is finally constructed. Experimental results and security analyses validate the effectiveness and superiority of the proposed cipher.

In this paper, a symmetric key block cipher cryptosystem is proposed, involving multiple twodimensional chaotic maps and using 128-bits external secret key. Computer simulations indicate that the cipher has good diffusion and confusion properties with respect to the plaintext and the key. Moreover, it produces ciphertext with random distribution. The computation time is much less than previous related works. Theoretic analysis verifies its superiority to previous cryptosystems against different types of attacks.

This paper presents an improved version of GLS-coding for simultaneous data compression and encryption called Range GLS-coding. It removes implementation issue of infinite precision real numbers due to long products of real numbers in GLS-Coding. This improvement increases the algorithm efficiency to almost double. Furthermore, encryption quality is improved by masking pseudorandom keystream; the secret key is incorporated by changing the direction and performing cyclic-shift operation in a complex piecewise linear chaotic map (PWLCM). Experimental results demonstrate that proposed algorithm has acceptable security and compression features. The overall algorithm provides simultaneous data encryption and compression and useful for real-time applications.

In recent years, the need for secured communication research based on Speech Coding with chaos cryptography has highly increased. Therefore, it is absolutely necessary to have secure systems to protect the transferred data against arbitrary intrusions. So, data encryption is an effective way to meet these requirements. In this paper, we propose a full and a partial speech encryption schemes based on chaos maps for AMR-WB G.722.2 Codec. To increase the security level, we combine chaos maps logistic and Hénon for shuffling and scrambling speech in order to have a hybrid chaotic key generator. The proposed algorithms evaluated with both Perceptual Evaluation of Speech Quality (PESQ) and Enhanced Modified Bark Spectral Distortion (EMBSD) measure confirm the efficiency of our proposed cryptosystem scheme.

Information Security is a primary concern of communication. Increasing rate of Image applications demands a good cryptosystem for image security. Unfortunately traditional cryptosystem is not very suitable for multimedia applications due to their statistical property while sensitivity to initial condition makes chaos very popular for image encryption. A variety of methods for image encryption based chaos have been developed in recent years. In this paper we are trying to discuss some of the chaos based algorithm for image encryption.

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Cryptography is a method of storing and transmitting data in a particular form so that only those for whom it is intended can read and process it. Cryptography includes techniques such as microdots, merging words with images, and other ways to hide information in storage or transit. However, in today's computer-centric world, cryptography is most often associated with scrambling plaintext (ordinary text, sometimes referred to as cleartext) into ciphertext (a process called encryption), then back again (known as decryption). Individuals who practice this field are known as cryptographers. To make a secure and successful transaction of message, the security of cipher text is must before transmission over communication channel. This paper propose a new encryption technique with the help of random segmentation and random re-arrangement of cipher text using two dimensional array before transmission over communication channel so that the transmitted cipher text is more complex to decr...

Based on the better properties of chaotic maps, the studies of chaotic-based image encryption have received much attentions by researchers in recent years. In this paper, an image encryption algorithm based on logistic map with substitution approach is proposed. Meanwhile, we make the line chart, histogram, and pixel loss analysis to show the performance of our algorithm.

In contradiction to one-dimensional mapping, higher-dimensional mapping may be conservative (volume preserving) as well as dissipative (volume contracting), invertible as well as non-invertible, depending on the parameter in the model. In this paper, we use two-dimensional chaotic maps, specifically Henon map [1], for compression as well as encryption. The Henon map is used to construct a privatekey block cryptosystem.

In this comment, we analyze a recently proposed Baptista-like cryptosystem and show that it is not invertible. Others weaknesses are also reported. A modified version of this cryptosystem is proposed to show how to overcome the non-invertibility.

With the development of chaos theory, many image encryption algorithmshave been designed using the properties associated withthechaotic map. The chaotic map shows high sensitivity to initial conditions and the sequence generated using chaotic map are unpredictable making it a good choice for performing encryption operation. But, without proper encryption algorithm design, encryption scheme designed based onthechaotic map can be cryptanalyzed to reveal the plain image. In this paper, an image encryption scheme based on chaotic tent map is cryptanalyzed using chosen-plaintext. Simulation results are shown where the plain image is successfully revealed from the cipher image without using the initial key used during encryption.

Security of multimedia data is a major concern due to its widespread transmission over various communication channels. Hence design and study of good image encryption schemes has become a major research topic. During the last few decades, there has been a increasing in chaos-based cryptography. This paper proposes an attack on a recently proposed chaos based image encryption scheme. The cryptosystem under study proceed by first shuffling the original image to disturb the arrangement of pixels by applying a chaotic map several times. Second, a keystream is generated using Chen's chaotic system to mix it with the shuffled pixels to finally obtain the cipher image. A chosen ciphertext attack can be done to recover the system without any knowledge of the key. It simply demands two pairs of plaintext-ciphertext to completely break the cryptosystem.

Security of multimedia data is a major concern due to its widespread transmission over various communication channels. Hence, design and study of good image encryption schemes has become a major research topic. During the last few decades, there has been an increase in chaos-based cryptography. This paper proposes an attack on a recently proposed chaos-based image encryption scheme. The cryptosystem under study proceeded by first shuffling the original image to disturb the arrangement of pixels by applying a chaotic map several times. Second, a key stream is generated using Chen’s chaotic system to mix it with the shuffled pixels to finally obtain the cipher image. A chosen-ciphertext attack can be done to recover the system without any knowledge of the key. It simply demands two pairs of plaintext–ciphertext to completely break the cryptosystem.

Global command and control system (GCCS-Joint) is a command, control, communications, computers and intelligence (C4I) system which consists of hardware, software, procedures and standards and which provides directory services, enterprise services and security services by exchanging imagery, intelligence, status of forces and planning information. In order to secure this exchange of imagery and information, we need more secure techniques and algorithms to be implemented. During the war, the commanders and forces needs the information and images of the exact location to which they are going to target and these images can be easily taken from the satellite. But the main problem of these satellite images is its transmission over the unsecure electronic media. This paper basically introduces a technique for the encryption and decryption of satellite imagery in order to securely transmit it during the war. The methodology used here for the process of encryption and decryption is that of chaotic maps. The research work is carried out by using the Henon and logistic maps.

We propose a general method for security evaluation of SNOW 2.0-like ciphers against correlation attacks that are built similarly to known attacks on SNOW 2.0. Unlike previously known methods, the method we propose is targeted at security proof and allows obtaining lower bounds for efficiency of attacks from the class under consideration directly using parameters of stream cipher components similarly to techniques for security proofs of block ciphers against linear cryptanalysis. The method proposed is based upon automata-theoretic approach to evaluation the imbalance of discrete functions. In particular, we obtain a matrix representation and upper bounds for imbalance of an arbitrary discrete function being realized by a sequence of finite automata. These results generalize a number of previously known statements on matrix (linear) representations for imbalance of functions having specified forms, and may be applied to security proofs for other stream ciphers against correlation attacks. Application of this method to SNOW 2.0 and Strumok ciphers shows that any of the considered correlation attacks on them over the field of the order 256 has an average time complexity not less than 20. 146

Encryption is to reorganize the message into discrepancy form so that the message is keep secret. The goal of encryption is to give an easy and inexpensive means of encryption and decryption to all authoritative users in possession of the suitable key and difficult and expensive means to estimate the plain text without use of the key. The Baptista proposed a Chaotic Encryption technique, which seems to be much better than traditional encryption methods used today. Chaotic encryption is the new trend of cryptography. It makes use of chaotic system properties such as sensitive to initial condition and lot of information. It is possible to encrypt a message (a text composed by some alphabet) using the Ergodic property of the simple low-dimensional and chaotic logistic equation. But it still has several problems, such as slow in speed and suffering from floating point operations and has less security. This paper is to overcome these problems with dynamic loop up table.

The residential environments are an important scenario for Ultra Wide Band (UWB) communication systems. In this paper, the performance of correlating receivers operating in a Line-Of-Sight (LOS) scenario in these environments is evalu- ated. In such channel the interference between users is an additional source of noise, that may deteriorate the performance of the system. In this research axis; it aims to exploit the richness of chaotic and spatiotemporal sequences with respect to topologic properties. We check through simulations, that chaotic sequences are shown to have improved performance compared to the Gold sequences in terms of Bit Error Rate (BER).

In this paper, we study basic dynamical behavior of one-dimensional Doubling map. Especially emphasis is given on the chaotic behaviors of the said map. Several approaches of chaotic behaviors by some pioneers it is found that the Doubling map is chaotic in different senses. We mainly focused on Orbit Analysis, Sensitivity to Initial Conditions, Sensitivity to Numerical Inaccuracies, Trajectories and Staircase Diagram of the Doubling map. The graphical representations show that this map is chaotic in different senses. The behavior of the said map is found irregular, that is, chaotic.

The data space for audio signals is large, the correlation is strong, and the traditional encryption algorithm cannot meet the needs of efficiency and safety. To solve this problem, an audio encryption algorithm based on Chen memristor chaotic system is proposed. The core idea of the algorithm is to encrypt the audio signal into the color image information. Most of the traditional audio encryption algorithms are transmitted in the form of noise, which makes it easy to attract the attention of attackers. In this paper, a special encryption method is used to obtain higher security. Firstly, the Fast Walsh–Hadamar Transform (FWHT) is used to compress and denoise the signal. Different from the Fast Fourier Transform (FFT) and the Discrete Cosine Transform (DCT), FWHT has good energy compression characteristics. In addition, compared with that of the triangular basis function of the Fast Fourier Transform, the rectangular basis function of the FWHT can be more effectively implemented in ...

A chaotic system for an image encryption and decr yption is the basic theme of this paper. Presentably many image encryption algorithms have b een proposed, based on one chaotic system. An image encryption and decryption scheme based on two chaot ic systems is being proposed. The scheme combines t he spatial – domain encryption of digital images and t he raditional stream cipher technology. The very w ide encrypting space is the main advantage of using two chaotic systems. In addition to chaotic sequences ar easy to control and easy to generate. The encryption pha se makes use of two chaotic sequences to encrypt an image. The reverse operation is carried out to recover ori ginal image in decryption phase.

Recently, a cryptosystem based on two-dimensional discretized chaotic maps was proposed [T. Xiang, et al., Phys. Lett. A 364 (2007) 252]. In this Letter, we cryptanalyze the proposal using algebraic methods. We give three different attacks that yield all the secret parameters of the cryptosystem.

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In this paper, we study basic dynamical behavior of one-dimensional Doubling map. Especially emphasis is given on the chaotic behaviors of the said map. Several approaches of chaotic behaviors by some pioneers it is found that the Doubling map is chaotic in different senses. We mainly focused on Orbit Analysis, Sensitivity to Initial Conditions, Sensitivity to Numerical Inaccuracies, Trajectories and Staircase Diagram of the Doubling map. The graphical representations show that this map is chaotic in different senses. The behavior of the said map is found irregular, that is, chaotic.

In this paper, a novel symmetric multiple image encryption algorithm is proposed. The scheme exploits the features of discrete wavelet transform, finite ridgelet transform and chaotic maps in a way to achieve completely distorted and meaningless single encrypted image which secretly contains the information of the original images. The four original images are first transformed in wavelet domain followed by the finite ridgelet transformations of their HH bands to get two combined transformed matrices. This on pixel values rotation using chaotic key image, mixing and then their shuffling using random sequences results into a final encrypted image. The piece-wise linear chaotic map and 2D gingerbreadman chaotic map are utilized to generate the chaotic key image and shuffling sequences, respectively. The encrypted image is highly distorted and meaningless for a casual observer. The mean square error between the pairs of decrypted and original images is less than 0.004. Moreover, the exp...

Chaos-based image encryption has great significance as a branch of image security. So, a series of chaos-based cryptosystems protecting digital images are proposed in recent years. But, most of them have been broken as a result of poor encryption structure. This research paper suggests an effective image encryption structure to resist possible attacks. The proposed method employs plain image related Henon map (PIHM) for shuffling and diffusion processes in a connected way which is different from conventional chaotic based image encryption systems, since the initial conditions of diffusion process are established based on the initial conditions of shuffling process. The principle of confusion is achieved by shuffling the pixels over all the rows and columns. And the diffusion is ensured by using XOR operation of current shuffled pixel value with the previous value, and random pixel produced from PIHM map. The results of simulation and security analysis indicate that the proposed sche...

The design of a secure, digital communication scheme based on the chaotic iterations of the logistic map is proposed. A two-stage encryption technique encapsulates encrypted initial conditions in a synchronization interval and produces a keystream varying with the plaintext, at sampling clock rate. A proof of concept is provided by means of simulation. The overall coincidence probability, demonstrated by the system depends on the accuracy of the fixed-point calculations. Keywords—Digital chaotic circuit, logistic map, chaotic synchronization, secure communication, chaotic encryption.