Numerical simulation is one of primary methods in which people study the property of chaotic systems. However, there is the effect of finite precision in all processors which can cause chaos to degenerate into a perio...
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Numerical simulation is one of primary methods in which people study the property of chaotic systems. However, there is the effect of finite precision in all processors which can cause chaos to degenerate into a periodic function or a fixed point. If it is neglected the precision of a computer processor for the binary numerical calculations, the numerical simulation results may not be accurate due to the chaotic nature of the system under study. New and more accurate methods must be found. A quantitative computable method of sequence complexity evaluation is introduced in this paper. The effect of finite precision is evaluated from the viewpoint of sequence complexity. The simulation results show that the correlation function based on information entropy can effectively reflect the complexity of pseudorandom sequences generated by a chaotic system, and it is superior to the other measure methods based on entropy. The finite calculation precision of the processor has significant effect on the complexity of chaotic binary sequences generated by the Lorenz equation. The pseudorandom binarysequences with high complexity can be generated by a chaotic system as long as the suitable computational precision and quantification algorithm are selected and behave correctly. The new methodology helps to gain insight into systems that may exist in various application domains such as secure communications and spectrum management.
In this letter, we will prove that chaotic binary sequences generated by the tent map and Walsh functions are i.i.d. (independent and identically distributed) and orthogonal to each other.
In this letter, we will prove that chaotic binary sequences generated by the tent map and Walsh functions are i.i.d. (independent and identically distributed) and orthogonal to each other.
In Monte-Carlo simulations, various types of random numbers are necessary for simulating various kinds of stochastic phenomena. Using one-dimensional chaotic maps, we can design statistical properties of the chaotic s...
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When chaotic systems are applied to stream ciphers, chaotic real-valued sequences generally need to be converted into binarysequences with the purpose of encrypting data. However, the performance of binarysequences ...
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When chaotic systems are applied to stream ciphers, chaotic real-valued sequences generally need to be converted into binarysequences with the purpose of encrypting data. However, the performance of binarysequences will be degraded under the joint influence of round-off and quantization errors. In this case, the randomness of some chaotic binary sequences may be weakened in a local range. Taking advantage of parallel computing, a fast period detection algorithm is designed to locate all local "periodicities" contained in chaotic binary sequences quickly and accurately. This algorithm evaluates the randomness of a chaotic binary sequence from a new perspective of periodicity which enriches the randomness test methods for binarysequences. Different logistic binarysequences are analyzed to demonstrate the effectiveness and practicability of the proposed algorithm.
It is well known that the periodic performance of spread spectrum sequence heavily affects the correlative and secure characteristics of communication systems. The chaotic binary sequence is paid more and more attenti...
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It is well known that the periodic performance of spread spectrum sequence heavily affects the correlative and secure characteristics of communication systems. The chaotic binary sequence is paid more and more attention since it is one kind of applicable spread spectrum sequences. However, there are unavoidable short cyclic problems for chaotic binary sequences in finite precision. The chaotic binary sequence generating methods are studied first. Then the short cyclic behavior of the chaoticsequences is analyzed in detail, which are generated by quantification approaches with finite word-length. At the same time, a chaotic similar function is defined for presenting the cyclic characteristics of the sequences. Based on these efforts, an improved method with scrambling control for generating chaotic binary sequences is proposed. To quantitatively describe the improvement of periodic performance of the sequences, an orthogonal estimator is also defined. Some simulating results are provided. From the theoretical deduction and the experimental results, it is concluded that the proposed method can effectively increase the period and raise the complexity of the chaoticsequences to some extent.
It has been proved that Local-Period phenomena widely exist in any chaotic binary sequences. Among the reasons of Local-Period phenomena, the quantifications of chaoticbinary random number generators are the key fact...
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It has been proved that Local-Period phenomena widely exist in any chaotic binary sequences. Among the reasons of Local-Period phenomena, the quantifications of chaoticbinary random number generators are the key factors. This paper proposed that different quantifications could make the generated sequences from the same chaotic real value sequence appear different randomness. Moreover, the simulation results illustrated that for the same Logistic real value sequence quantified by different quantifications, such as L-bits quantification, C-threshold quantification and Region quantification, Local-Period phenomena are located in different places by binarysequence period detection (BSPD) detecting method. Meanwhile, statistical data inferred that C-threshold quantification has less effect on the randomness of original chaotic real value sequence.
The pseudo-randomness and complexity of binarysequences generated by chaotic systems are investigated in this paper. These chaotic binary sequences can have the same pseudo-randomness and complexity as the chaotic re...
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The pseudo-randomness and complexity of binarysequences generated by chaotic systems are investigated in this paper. These chaotic binary sequences can have the same pseudo-randomness and complexity as the chaotic real sequences that are transformed into them by the use of Kohda's quantification algorithm. The statistical test, correlation function, spectral analysis, Lempel-Ziv complexity and approximate entropy are regarded as quantitative measures to characterize the pseudo-randomness and complexity of these binarysequences. The experimental results show the finite binarysequences generated by the chaotic systems have good properties with the pseudo-randomness and complexity of sequences. However, the pseudo-randomness and complexity of sequence are not added with the increase of sequence length. On the contrary, they steadily decrease with the increase of sequence length in the criterion of approximate entropy and statistical test. The constraint of computational precision is a fundamental reason resulting in the problem. So only the shorter binarysequences generated by the chaotic systems are suitable for modern cryptography without other way of adding sequence complexity in the existing computer system. (C) 2010 Elsevier B.V. All rights reserved.
A scheme is proposed in which a watermark is transformed and then used to modify the third, fourth, or fifth bit of the pixels in a permuted image according to a chaotic binary sequence. The PSNR is larger than 44dB a...
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A scheme is proposed in which a watermark is transformed and then used to modify the third, fourth, or fifth bit of the pixels in a permuted image according to a chaotic binary sequence. The PSNR is larger than 44dB and the extracted watermarks are still recognisable when the compression ratio reaches 39%.
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