Study On Image Encryption Algorithm Under The Dual Chaotic System

Along with social progress and rapid development of science and technology, people's communion becomes more and more closely, and the image information exchange has become an important channel for exchange of mankind. Although the image transmission of information provides a great convenience for people, its security issues received extensive attention at the same time. Encryption technology is the most effective means of protecting information security, many scholars has made very fruitful results. However, these encryption technologies is still not perfect, and with the theoretical study of encryption , many encryption methods are under attack, there is an urgent need to develop a new theory of information security and advanced encryption technology.Conventional encryption algorithm encryption fits in with text and is not entirely suitable for image data encryption. In order to adapt to the inherent characteristics of the image and improve the efficiency and security of image encryption, the need for proposing a new image encryption scheme. The basic features of many chaotic systems such as: Ergodicity, mixing, certainty and extreme sensitivity to initial conditions, can be in contact with the confusion and proliferation of cryptography. Thus chaos theory can be directly used to design cryptographic algorithms, it also provides a new research way for image encryption. Generally it requires the use of digital circuits such algorithms or computer software, so it called chaos cryptographic algorithms. Nowadays chaos cryptographic algorithm development has its problems: currently there is a lack of an overall feasibility of their security theory; limited computing precision effect caused degradation of the dynamics of chaotic systems. For the former, the test of chaos encryption is particularly important. For the latter, we can adopt a number of chaotic systems and disturbance strategies to improve it. Meanwhile, conventional encryption security is in possession of the complete support of the mathematical theory, the use of the combination between conventional code and chaos cipher is expected to constitute a good cipher security algorithm.Therefore, in order to provide the large number of non-related, determined, similar to random and reproducible signals, we can use the sensitive dependence of the initial value and structural parameters.And we can use the many other advantages such as: the pseudo-randomness, the unpredictability of the track, the extreme sensitivity of the initial state and the structural parameters, in order to design the well-constructed image data encryption system.The following tasks have been accomplished in this paper:1) Cryptography research status and the list of several mature type of cipher encryption are introduced, and then their respective trends are analyzed.2) Chaos theory is discussed in detail in many ways. Firstly, the history of chaos theory and its development trend are discussed. Secondly, the definition of chaos, the characteristics of chaos and chaotic introduction of the necessary criteria and guidelines are given. At last the several common chaotic models are introduced in brief.3) The common image encryption technologies are introduced firstly. And the separate encryption system based on Logistic map, chaotic block cipher encryption system and dual chaotic encryption system are described and theoretical supported for the argument.4) The images of the three encryption model are evaluated respectively. And the length of the key space, histogram analysis, the key sensitivity, pixel correlation and analysis of resistance to differential attacks are evaluated especially.5) Finally, the research work of this paper is summarized, and the future developing direction is indicated.