基于数字混沌的图像选择加密算法的研究计算机系统结构专业论文.docxVIP

重庆大学硕士学位论文英文 重庆大学硕士学位论文 英文摘要 PAGE PAGE IV ABSTRACT In recent years, computer technology and the Internet is developing rapidly and dramatically changing peoples life. Multimedia is a newly born technology which is generated accompanied with these two technologies. Therefore, to protect the security of multimedia information has become a growing consideration. It is widely agreed that the cryptography is the important method to resolve it. Because of the large size of multimedia data, it will cost more resources and time if people encrypt the whole bunch of data. Therefore, selective encryption becomes an important tool. Digital image is a kind of multimedia information, and the research results can be extended to other media forms. During the image transmission process, we use two kinds of encryptions: the confidentiality encryption and the degradation encryption for different purposes. In the image degradation encryption, in order to meet the purchasing model of “try before you buy”, it allows users to see a part of the image before they decide to buy. If the user is interested in the image, we can provide the decryption keys to him online or offline so he can decrypt the image to get full details. According to the natural characteristics of image information, we found that some of the traditional image encryption algorithms are not suitable in practical applications because there are many flaws and shortcomings. In recent years, many scholars have put forward some new encryption algorithms for image degradation, but these algorithms also have shortcomings and deficiencies. Therefore, in this paper, we present an image degradation encryption algorithm which leverages the advantages of wavelet transform and the characteristics of chaotic map which are used to select the main information of image and overcome the previous deficiencies respectively. Confidentiality encryption is a traditional image encryption mode which preserves the main content of the image again