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      • KCI등재

        CDSK 방식의 디지털 카오스 통신 시스템

        복준영(Junyeong Bok),유흥균(Heung-Gyoon Ryu) 한국통신학회 2013 韓國通信學會論文誌 Vol.38 No.6C

        최근 정보 보안이 중요시됨에 따라서 향상된 보안성과 낮은 도청 확률을 가지는 무선 통신 기술에 대한 관심이 급격히 증가하고 있다. 카오스 신호는 불규칙한 현상으로 인하여 정보를 효율적으로 부호화 하는데 적용할 수 있다. 카오스 신호는 초기 조건에 매우 민감하며 초기 조건을 모른다면 신호의 감지가 어렵다는 단점을 가지고 있지만 다중 경로 간섭에 강한 장점을 가진다. 본 논문에서는 디지털 카오스 변조 방식인 CDSK 방식에서 여러 가지 카오스 맵을 적용하여 수신 성능을 평가한다. 또한, CDSK 방식에서 확산인자 (Spreading factor)의 변화에 따른 수신 BER 성능을 분석한다. 시뮬레이션 결과, Hennon map을 사용할 경우 다른 Chaotic map들 보다 훨씬 좋은 수신 성능을 얻을 수 있었으며, 확산인자가 70에서 가장 좋은 수신 BER 성능을 얻는 것을 확인하였다. Recently, interest for wireless communication technology with improved security and low eavesdropping probability is increasing rapidly recognizing that information security is an important. Chaos signal can be used encode information efficiently due to irregular phenomena. Chaotic signal is very sensitive to the initial condition. Chaos signal is difficult to detect the signal if you do not know the initial conditions. Also, chaotic signal has robustness to multipath interference. In this paper, we evaluate the performance of correlation delay shift keying (CDSK) modulation with different chaotic map such as Tent map, Logistic map, Henon map, and Bernoulli shift map. Also, we analyze the BER performance depending on the selection of spreading factor (SF) in CDSK. Through the theoretical analyses and simulations, it is confirmed that Henon map has better BER performance than the other three chaotic maps when spreading factor is 70.

      • KCI등재

        DCSK와 CDSK 방식을 사용하는 카오스 통신 시스템의 항재밍 특성

        이준현(Jun-Hyun Lee),유흥균(Heung-Gyoon Ryu) 한국전자파학회 2013 한국전자파학회논문지 Vol.24 No.4

        디지털 통신 기술은 보다 높은 데이터 효율과 정보의 효율적인 부호화에 초점을 맞추고 있다. 또한, 보안성을 높이고 외부 요인의 간섭을 최소화하는 것이 중요하다. DCSK(Differential Chaos Shift Keying)나 CDSK(Correlation Delay Shift Keying)와 같은 비선형 시스템에서는 정보를 효율적으로 부호화하여 보안성을 높이고 외부 요인의 간섭을 최소화시키는 방법으로 카오스 통신 시스템을 많이 사용하고 있다. 본 논문에서는 DCSK 방식과 CDSK 방식에 카오스 맵을 적용하여 카오스 통신 시스템의 BER 성능과 정보의 항재밍 특성을 평가한다. 시뮬레이션을 통해 Gauss iterated map이 다른 3개의 카오스 맵보다 좋은 성능을 얻을 수 있다는 것을 알 수 있다. 또한, DCSK 방식과 CDSK 방식은 카오스 맵을 적용함으로써 더 좋은 항재밍 특성을 얻을 수 있다. Digital communication technology have been focused on the higher data efficiency and the effective coding of information. Also, it is very important to improve security and minimize the interference of the external sources, Chaos communications system is studied to improve security and minimize the interference by effective encoding of information in the nonlinear systems such as DCSK(Differential Chaos Shift Keying) and CDSK(Correlation Delay Shift Keying). In this paper, we evaluate anti-jamming performance of chaos communications system using the DCSK and CDSK system. The simulation results show that the Gauss iterated map has better BER performance than the other maps(tent map, logistic map, Henon map). Also, DCSK and CDSK system can get the better anti-jamming performance by applying different chaotic maps.

      • KCI등재

        Image Encryption Based on Quadruple Encryption using Henon and Circle Chaotic Maps

        Hanchinamani, Gururaj,Kulkarni, Linganagouda Korea Multimedia Society 2015 The journal of multimedia information system Vol.2 No.2

        In this paper a new approach for image encryption based on quadruple encryption with dual chaotic maps is proposed. The encryption process is performed with quadruple encryption by invoking the encrypt and decrypt routines with different keys in the sequence EDEE. The decryption process is performed in the reverse direction DDED. The key generation for the quadruple encryption is achieved with a 1D Circle map. The chaotic values for the encrypt and decrypt routines are generated by using a 2D Henon map. The Encrypt routine E is composed of three stages i.e. permutation, pixel value rotation and diffusion. The permutation is achieved by: row and column scrambling with chaotic values, exchanging the lower and the upper principal and secondary diagonal elements based on the chaotic values. The second stage circularly rotates all the pixel values based on the chaotic values. The last stage performs the diffusion in two directions (forward and backward) with two previously diffused pixels and two chaotic values. The security and performance of the proposed scheme are assessed thoroughly by using the key space, statistical, differential, entropy and performance analysis. The proposed scheme is computationally fast with security intact.

      • Bit-Level Image Encryption Algorithm Based on Composite Chaotic Mapping

        Cai Yang,Haiyu Zhang,Jinliang Guo,Songhao Jia,Fangfang Li 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.8

        Because the single chaotic mapping easily creates security weaknesses in the image encryption algorithm, the security needs to be improved. Aiming at this problem, a bit-level image encryption algorithm based on composite chaotic mapping (CCM-IEA) is proposed. First of all, the algorithm scrambles the plain image on bit level through the Cat mapping for the first time. And then the Henon mapping of two dimensional discrete is used to scramble for the second time. Finally, image diffusion is operated through the one dimensional Logistic mapping, and the data sensitivity is enhanced. The experimental results show that the performance of the CCM-IEA algorithm is better on the histogram, information entropy and correlation analysis. Compared with the single chaotic images encryption algorithm, the CCM-IEA algorithm has the ability to resist the information entropy analysis and correlation analysis. It can be seen that the CCM-IEA algorithm has high safety performance and good encryption effect.

      • KCI등재

        혼돈신호에 따른 암호화 정도 분석

        임거수(Geo-Su Yim) 한국정보기술학회 2009 한국정보기술학회논문지 Vol.7 No.6

        The Chaotic system using encoding methods has seen a great deal of research being conducted in data communication and image encoding. For more effective encoding methods, researchers have created a complicated chaotic system, and employ the signals generated from the said system in encoding. In the study, it was identified that variation of probability distribution which appears in the time series, a used signal in the chaotic system, has a big impact on the efficiency of encoding. In order to present this impact in a numerical mode, a correlation coefficient of data following encoding was calculated with the subsequent image encoding. In this paper, we propose that the method is a new effective encryption algorithm as well as easily application one.

      • SCIESCOPUSKCI등재

        HYPERBOLICITY AND SUSTAINABILITY OF ORBITS

        Fornaess, John-Erik Korean Mathematical Society 2003 대한수학회지 Vol.40 No.3

        Let $F: \mathbb{C}^k\;{\rightarrow}\;\mathbb{C}^k$ be a dynamical system and let $\{x_n\}_{n{\geq}0}$ denote an orbit of F. We study the relation between $\{x_n\}$ and pseudoorbits $\{y_n}, y_0=x_0.\;Here\;y_{n+1}=F(y_n)+s_n.$ In general $y_n$ might diverge away from $x_n.$ Our main problem is whether there exists arbitrarily small $t_n$ so that if $\tilde{y}_{n+1}=F(\tilde{y}_n)+s_n+t_n,$ then $\tilde{y}_n$ remains close to $x_n.$ This leads naturally to the concept of sustainable orbits, and their existence seems to be closely related to the concept of hyperbolicity, although they are not in general equivalent.

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