| With the rapid development and wide applications of Internet technology and media technology,more and more information has been quickly and conveniently transmitted through the network, and become one of the important means for people to access information,at the same time there arouses the potential problems of the information security. When those images, involving some important information such as national secrets,commercial or individual privacy, transmitted through the network, the security of image information is becoming very important. Therefore,how to protect information security has become a hot topic. Encryption technology is the best method to protect information security, which is greatly practical and urgent to develop key technology.However,on one hand,most encryption methods are designed for text information; on the other hand,some encryption schemes are easily to be attacked.There are many disadvantages in traditional encryptions,and a lot of encryptions for images are put forward.In fact,there are more or less disadvantages in one signal encryption.This paper studies on chaotic technology and its application in digital imageencryption.The contributions of this dissertation can be summarized as follows:Chapter 1 is the introduction of this thesis.It gives the outline of the research work.This thesis firstly introduces the principle of image encryption in Chapter2, which is useful for our understanding of following chapters,and later in Chapter 3 introduces the basic knowledge of chaos,including its concept, characteristics and models,then make analysis for several classical chaotic maps. These are the foundation of our research work.In Chapter 4, we discussed how to use the chaos system to image encryption,the basis theory and its method of image encryption, and we analyzed the result of emluator experimental which based the Logistic map.In Chapter 5, present a new image encryption algorithm base chaotic sequences,and designed the substitution and diffusion system. Finally the conclusion is given, including the advantage and disadvantage of the work.This paper analyses the image encryption algorithms from these aspects, including sensitive dependence on the key, histogram,correlation of adjacent pixels and ect.The conclusion can be drawn that these algorithms can encrypt/decrypt image effectively,with the good effect of confusion, sensitive dependence on the key,better stability and high speed execution. Both theory analysis and experimental test have proved the security of the proposed cryptosystems. |
