Research And Implementation Of Image Encryption Algorithm Based On Chaotic System

In recent years, with the development of communication technique, there are a great many digital images in web system and distributed multimedia system. Because of the development of communication, gaining data becomes more and more easy illegally through common and wireless communication. Therefore, information security becomes one important problem, and digital image technique has already been useful and needs to be further developed. The most effective method that protect digital images is encryption. However, on one side, most encryption method is desinged for text information, on the other side, some encryption is easily to be attacked. There are many disadvantages in traditional encryptions, and a lot of encryptions for images are putforward. In fact, there are more or less disadvantages in one singal encryption. This thesis firstly introduces image encryption in Chapter 1, which is useful for our understanding of following chapters, and later in Chapter 2 introduces the basic knowledge of chaos, including its concept , character and models. Then discusses image encryption methods in,Chapter 4,Chapter 5,including 3 parts of content: (1)improves the traditional encryption,combines mirror transformation and rubik cube tranformation, proposes"Modified image encryption based on chaotic sequences and rubik cube transformation".Both cubic transformation and mirror transformation are realized through scrambling of pixls, so combination of both is feasible.This is introduced in Chapter 3 (2)S-box is nonlinear part among most block-cipher,and it provides security.Based on S-box,propose"An image encryption means based on rijndael". This is introduced in Chapter 4 (3)in encryption with compression, nearly all images are needed to be compressed before transfored because of big image size.So cryptosystem combined with compression is amazing . Based on wavelet, proposes"Image encryption based on wavelet dicrete transformation". Finally the conclusion is given, including the advantage and disadvantage of the work.This thesis fouses on two aspects-- image encryption in spatial domain and in frequency domain.Both theory analysis and experiment show security in the proposed cryptosystems.