Stream Cipher from Chaotic Systems and High Gain Observers

2019 ◽  
Author(s):  
Ines Daldoul ◽  
Ali Sghaier Tlili
Keyword(s):  
Chaotic Systems ◽  
Stream Cipher ◽  
High Gain

SPEED-GRADIENT ADAPTIVE HIGH-GAIN OBSERVERS FOR SYNCHRONIZATION OF CHAOTIC SYSTEMS

2007 ◽  
Vol 40 (13) ◽  
pp. 232-237
Author(s):  
Antonio Loría ◽  
Elena Panteley ◽  
Arturo Zavala
Keyword(s):  
Chaotic Systems ◽  
High Gain ◽  
Speed Gradient

scholarly journals Robust Synchronization of Class Chaotic Systems Using Novel Time-Varying Gain Disturbance Observer-Based Sliding Mode Control

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yang Wang ◽  
Zhen Wang ◽  
Lingyun Kong
Keyword(s):  
Sliding Mode Control ◽  
Disturbance Observer ◽  
Chaotic Systems ◽  
Sliding Mode ◽  
High Gain ◽  
Time Varying ◽  
Mode Control ◽  
Control Precision ◽  
Robust Synchronization ◽  
And Control

For synchronization of a class of chaotic systems in the presence of nonvanishing uncertainties, a novel time-varying gain observer-based sliding mode control is proposed. First, a novel time-varying gain disturbance observer (TVGDO) is developed to estimate the uncertainties. Then, by using the output of TVGDO to modify sliding mode control (SMC), a new TVGDO-based SMC scheme is developed. Although the observation and control precision of conventional fixed gain disturbance observer-based control (FGDOC) for chaotic systems can be guaranteed by a high observer gain, the undesirable spike problem may be caused by the high gain if the initial values of estimate and true states are not equal. The most attractive feature of this work is that the newly proposed TVGDO can eliminate the spike problem by developing a time-varying gain scheme. Finally, the effectiveness of the proposed method is demonstrated by the numerical simulation.

DIGITAL STREAM CIPHER BASED ON SCS-PRBG

2009 ◽  
Vol 23 (25) ◽  
pp. 5085-5092
Author(s):  
XINGYUAN WANG ◽  
WEI LIU ◽  
NINI GU ◽  
HUAGUANG ZHANG
Keyword(s):  
Parallel Computation ◽  
Chaotic System ◽  
Chaotic Systems ◽  
Stream Cipher ◽  
Theoretic Analysis ◽  
Switch Control ◽  
Random Bit Generator ◽  
And Performance ◽  
Multiple Chaotic Systems

Limitations caused by degeneration of dynamics characteristics may exist in the traditional single chaotic system. The authors propose a method i.e., switch controller chaos and pseudo random bit generator (it is called SCS-PRBG for short), which is based on multiple chaotic systems and switch control. By the theoretic analysis of random key stream and performance of SCS-PRBG, we can see that its digital stream cipher has better randomicity and security. And if using hardware parallel computation, the speed of encryption can be improved sharply. The results of the experiments also present better security of this arithmetic.

Observer-Based Synchronization of Chaotic Systems with Both Parameter Uncertainties and Channel Noise

2014 ◽  
Vol 24 (07) ◽  
pp. 1450095 ◽  
Author(s):  
Xiu Jiang ◽  
Junqi Yang ◽  
Fanglai Zhu ◽  
Liyun Xu
Keyword(s):  
Secure Communication ◽  
Chaotic Systems ◽  
Sliding Mode ◽  
High Gain ◽  
High Order ◽  
Sliding Mode Observer ◽  
Channel Noise ◽  
Parameter Uncertainties ◽  
Reduced Order ◽  
Reduced Order Observer

This paper considers observer-based chaos synchronization and chaos-based secure communication problems for a class of uncertain chaotic systems with both parameter uncertainties and channel noise. First, by introducing an augmented vector, the original system is transformed into a new system which has no channel noise. Second, based on the concept of relative degree, an auxiliary drive signal vector is constructed so that the observer matching condition is satisfied. Third, a reduced-order observer is designed to estimate the states of the new augmented system. Then, a high-order high-gain sliding mode observer is considered to estimate the auxiliary drive signals and their derivatives exactly in a finite time. After this, the combination of the reduced-order observer and the high-order high-gain sliding mode observer is used as the receiver in the secure communication mechanism. And a kind of secure information recovery method is developed. Finally, a four-dimensional hyperchaos system is used as the simulation example to illustrate the effectiveness of the proposed methods.

DESIGN OF CHAOTIC PSEUDO-RANDOM BIT GENERATOR AND ITS APPLICATIONS IN STREAM-CIPHER CRYPTOGRAPHY

2008 ◽  
Vol 19 (05) ◽  
pp. 813-820 ◽  
Author(s):  
XING-YUAN WANG ◽  
XIAO-JUAN WANG
Keyword(s):  
Cycle Length ◽  
Chaotic Systems ◽  
Stream Cipher ◽  
Initial Conditions ◽  
Piecewise Linear ◽  
Chaotic Map ◽  
Control Parameters ◽  
One Dimensional ◽  
Piecewise Linear Chaotic Map ◽  
Encryption And Decryption

Because of the sensitivity of chaotic systems on initial conditions/control parameters, when chaotic systems are realized in a discrete space with finite states, the dynamical properties will be far different from the ones described by the continuous chaos theory, and some degradation will arise. This problem will cause the chaotic trajectory eventually periodic. In order to solve the problem, a new binary stream-cipher algorithm based on one-dimensional piecewise linear chaotic map is proposed in this paper. In the process of encryption and decryption, we employ a secret variant to perturb the chaotic trajectory and the control parameter to lengthen the cycle-length of chaotic trajectory. In addition, we design a nonlinear principle to generate a pseudo-random chaotic bit sequence as key stream. Cryptanalysis shows that the cryptosystem is of high security.

Design of a High Gain Observer Optimization Method for the State Synchronization of Nonlinear Perturbed Chaotic Systems

2018 ◽  
Vol 13 (11) ◽  
Author(s):  
Ines Daldoul ◽  
Ali Sghaier Tlili
Keyword(s):  
Chaotic Systems ◽  
Correction Term ◽  
Salient Feature ◽  
Optimization Method ◽  
High Gain ◽  
Optimization Criterion ◽  
The State ◽  
Observation Error ◽  
High Gain Observer ◽  
The Cost

This paper propounds addressing the design of a high gain observer optimization method in order to ensure a reliable state synchronization of nonlinear perturbed chaotic systems. The salient feature of the developed approach lies in the optimization of the high gain observer by using the optimal control theory associated with a proposed numerical algorithm. Thereby, an innovative quadratic optimization criterion is proposed to calculate the required optimal value of the observer setting parameter θ, characterizing the observation gain and corresponding to the minimal value of the cost function, by achieving a compromise between the correction term of the state observer and its observation error. Moreover, the exponential stability of the high gain observer is demonstrated within the Lyapunov framework. The efficacy of the designed approach is highlighted by numerical simulation on two prominent examples of nonlinear perturbed chaotic systems.

Hyperchaos based Cryptography: New Seven Dimensional Systems to Secure Communications

2017 ◽  
Vol 2 (2) ◽  
pp. 20-30 ◽  
Author(s):  
S.N. Lagmiri ◽  
M. Amghar ◽  
N. Sbiti
Keyword(s):  
High Performance ◽  
Chaotic Systems ◽  
High Gain ◽  
Secure Communications ◽  
Initial Condition ◽  
Chaotic Signals ◽  
Chaotic Cryptography ◽  
Error Dynamics ◽  
Hyperchaotic Systems ◽  
Order Continuous

The growth of technology and the emphasis on privacy have intensified the need to find a fast and secure cryptographic method. As chaotic signals are usually noise-like and chaotic systems are very sensitive to the initial condition, they can be used in cryptography. We have analyzed the properties of two new hyperchaotic systems that we have developed and then propose a secure chaotic cryptography scheme for the transmission of confidential communication. The purpose of this article is to synchronize our two new hyperchaotic systems. These new systems are the fourth-order and six-order continuous hyperchaotic systems. After studying and verifying the hyperchaotic bihaviour of these systems, a high gain observer class is used to synchronize and stabilize the synchronization error dynamics. Then, a chaotic masking scheme is applied to secure the information between a transmitter and a receiver. The results of the simulations confirm the high performance of the observer designed for these high-dimensional systems and the proposed method leads to an almost perfect restoration of the original signal.

A SCALAR SIGN FUNCTION APPROACH TO DIGITAL CONTROL OF CONTINUOUS-TIME CHAOTIC SYSTEMS WITH STATE CONSTRAINTS

2009 ◽  
Vol 19 (06) ◽  
pp. 2009-2029 ◽  
Author(s):  
JIAN WU ◽  
LEANG S. SHIEH ◽  
JASON S. H. TSAI
Keyword(s):  
Nonlinear System ◽  
Continuous Time ◽  
Digital Control ◽  
Chaotic Systems ◽  
State Constraints ◽  
High Gain ◽  
Operating Point ◽  
Matrix Sign Function ◽  
Sign Function ◽  
Absolute Value

In this paper, a scalar sign function-based digital design methodology is presented to develop a digital tracking controller for the continuous-time chaotic systems with absolute value state constraints. A scalar sign function, which is the counterpart of the well-known matrix sign function, is utilized to approximately represent the absolute value state term by a rational function. As a result, the original state constrained nonsmooth nonlinear system becomes a smooth nonlinear system having rational nonlinear terms. Then, an optimal linearization technique is applied to the afore-mentioned nonlinear system for finding an optimal linearization model, which has the exact dynamics of the original nonlinear system at any operating point of interest with minimal modeling error in the vicinity of the operating point on the trajectory. To overcome the effect of modeling errors and to quickly track the desired reference signals, a high-gain optimal analog tracker is designed for the obtained linear model. For practical implementation of the high-gain analog tracker, the prediction-based digital redesign technique is utilized to obtain a low-gain digital tracker for digital control of the sampled-data nonlinear system with constrained states. Chua's chaotic circuits are used to demonstrate the effectiveness of the proposed approach.

Design and ARM Platform-Based Realization of Digital Color Image Encryption and Decryption via Single State Variable Feedback Control

2014 ◽  
Vol 24 (04) ◽  
pp. 1450049 ◽  
Author(s):  
Hanzhong Zheng ◽  
Simin Yu ◽  
Jinhu Lü
Keyword(s):  
Feedback Control ◽  
Image Encryption ◽  
Discrete Time ◽  
Chaotic Systems ◽  
Stream Cipher ◽  
Color Image ◽  
Color Image Encryption ◽  
State Variable ◽  
Encryption And Decryption ◽  
Single State

In this paper, discrete-time chaotic systems under single state variable feedback control are studied, and drive-response synchronization is investigated. To that end, ARM platform-based digital color image encryption and decryption using a chaotic stream cipher is designed and implemented, with experimental results demonstrated.

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