• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.99-104
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• 2000

In this paper, as a digital watermark we propose to use a chaotic sequence instead of the conventional Gaussian sequence. It is relatively easy to generate the chaotic sequence and is very sensitive to the change of initial value. The chaotic sequence adopted in this paper is a modified version of logistic map to give the sequence distribution of Chebyshev map. In the experiments, we applied the Gaussian sequence and chaotic sequence to wavelet coefficients of images to compare the similarity distribution. The results show that, as id the DCT-based watermarking system, the chaotic sequence is robust for various signal processing attacks, Moreover, the similarity variance is smaller than the Gaussian sequence for iterative experiments. It also shows a better performance for compression errors than the Gaussian sequence.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.630-637
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• 2003

This paper proposed a new watermarking algorithm using chaotic sequence instead of conventional M-sequence for protecting copyright to the author. Robustness and security is very important for watermarking process. We use multi-threshold value according to the human visual system for improving robustness of watermarking to each subband images coefficient differently after wavelet transform. And then, we embedded watermark image to original image by multi-watermark weights which are made by random sequence generator. We detect watermark image from the difference data which is made from each wavelet subband images. We also simulate the efficiency from the various possible attacks. Chaotic sequence is better than M-sequence, because the one is very easy to make sequence and the chaotic sequence is changed easy according to the initial value. So, the chaotic sequence has the better security than the conventional M-sequence.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.1 s.116
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• pp.90-95
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• 2007

Chaotic OOK(On-Off Keying) modulation method can be used in LDR(Low Data Rate) UWB systems. The chaotic generator in one of the most important circuit in this system. The traditional chaotic generator circuits using analog feed back technique have low yield characteristic due to the process variation. A novel quasi-chaotic signal generator using digital PN-sequence in proposed in this paper and verified in 0.18um CMOS teleology.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.9
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• pp.4645-4664
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• 2019

It is significant to construct deterministic measurement matrices with easy hardware implementation, good sensing performance and good cryptographic property for practical compressed sensing (CS) applications. In this paper, a deterministic construction method of bipolar chaotic measurement matrices is presented based on binary sequence family (BSF) and Chebyshev chaotic sequence. The column vectors of these matrices are the sequences of BSF, where 1 is substituted with -1 and 0 is with 1. The proposed matrices, which exploit the pseudo-randomness of Chebyshev sequence, are sensitive to the initial state. The performance of proposed matrices is analyzed from the perspective of coherence. Theoretical analysis and simulation experiments show that the proposed matrices have limited influence on the recovery accuracy in different initial states and they outperform their Gaussian and Bernoulli counterparts in recovery accuracy. The proposed matrices can make the hardware implement easy by means of linear feedback shift register (LFSR) structures and numeric converter, which is conducive to practical CS.

• The Journal of the Korea Contents Association
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• v.8 no.7
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• pp.53-57
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• 2008

The discretized saw-tooth map with the 16-bit finite precision which is one of the 1-dimensional chaotic maps is designed, and the circuit of chaotic binary sequence generator using the discretized saw-tooth map is presented also in this brief. The real implementation of designed chaotic map is accomplished by connecting the input and output lines exactly according to the simplified Boolean functions of output variables obtained from truth table which is discretized. The random binary output sequences generated by mLFSR generator were used for the inputs of descretized saw-tooth map, and, by the descretized map, chaotic binary sequence which has more long period of 16 times minimally is generated as a results.

• Journal of Multimedia Information System
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• v.8 no.2
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• pp.131-142
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• 2021

This paper traces the process of constructing a new one-dimensional chaotic map, and will provide a simple application in color image encryption. The use of Sarkovskii's theorem will make it possible to determine the existence of chaos and restrict all conditions to ensure the existence of this new sequence. In addition, the sensitivity to initial conditions will be proved by Lyapunov's index value. Similarly, the performance of this new chaotic map will be illustrated graphically and compared with other chaotic maps most commonly used in cryptography. Finally, a humble color image encryption application will show the power of this new chaotic map.

• Bulletin of the Korean Mathematical Society
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• v.57 no.1
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• pp.95-108
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• 2020

The aim of this paper is to show that for the one-sided symbolic system, there exist an uncountable distributively chaotic set contained in the set of irregularly recurrent points and an uncountable distributively chaotic set in a sequence contained in the set of proper positive upper Banach density recurrent points.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.2
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• pp.411-418
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• 2018

This paper presents a novel three-dimensional (3D) object encryption scheme by combining the use of the virtual optics and the chaotic sequence. A virtual 3D object is digitally produced using a two-dimensional (2D) elemental image array (EIA) created with a virtual pinhole array. Then, through a logistic mapping of chaotic sequence, a final encrypted video can be produced. Such method converts the value of a pixel which is the basic information of an image. Therefore, it gives an improved encryption result compared to other existing methods. Through computational experiments, we were able to verify our method's feasibility and effectiveness.

• ETRI Journal
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• v.28 no.2
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• pp.250-252
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• 2006

In this letter, a discrete state, discrete time chaotic pseudo random number generator (CPRNG) is presented for stream ciphering of text, audio, or image data. The CPRNG is treated as a finite state machine, and its state is modulated according to the input bit sequence of the signal to be encrypted. The modulated state sequence obtained can be transmitted as a spread spectrum or encrypted data.

• The KIPS Transactions:PartB
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• v.10B no.5
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• pp.485-490
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• 2003

In this paper, we propose the possibility of introducing chaotic sequences into digital watermarking systems as potential substitutes to commonly used pseudo noise sequences. Chaotic sequences have several good properties including the availability of a great number of them, the ease of their generation, as well as their sensitive dependence on their initial conditions. And the quantization does not destroy the good property. So this paper proposes a method that transforms Hangul text to chaotic sequence. And we presents how the Hangul text is expressed by an implied data and the implied data is regenerated into the original text. In this paper, we use this implied Hangul text for watermarking.