外文原文1-一个基于修改后的Logistics映射的图片加密方案.docVIP

2011 Fourth International Workshop on Chaos-Fractals Theories and Applications An Image Encryption Scheme Based on Modified Logistic Map Yue Sun School of Electronics Information Hangzhou Dianzi University Hangzhou, China e-mail: sunyue328@126.com Abstract—In order to improve the security of chaotic encryption algorithm, a modified chaotic map, which is based on the Logistic map, is proposed in this paper. Compared with original logistic map，the proposed map makes it always be chaotic, and expands the iteration range from original (0, 1) to (0, 4λ) (λ0.25). We designed an encryption scheme based on the proposed map for implementing image encryption. Some simulation results show that the modified Logistic map possesses bigger key space, faster sequence generation rate and faster encryption speed compared with the original logistic map. Keywords-chaos; modified logistic map; encryption Guangyi Wang School of Electronics Information Hangzhou Dianzi University Hangzhou, China e-mail: wanggyi@163.com I. INTRODUCTION In recent years, digital information has been widely used in many fields. Any of us has a lot of private multimedia sources and these sources should be protected from any kind of unauthorized manipulation. Chaos has nonlinear dynamic behaviou and chaotic sequence is paseudorandom and sensitive to the initial conditions [1]. Because of the nature of chaotic sequence, it is widely used in cryptology, control and communications [2-7]. Discrete chaotic system has high efficiency but low security because the range of its key space is smal， while continuous chaotic system has higher security, but low efficiency, because its calculation is complex. This paper proposes a modified Logistic map, which contains two parameters and can expand its onto mapping from original 0 - 1 to 0 - 4λ (λ 0.25) . This is important for expanding key space of chaotic sequence and enhancing rate of change of chaotic signal. An encryption algor