【作者】 商艳红；

【导师】 邹建成；

【作者基本信息】 北方工业大学 ， 计算机应用技术， 2005， 硕士

【摘要】 当今,数字图像的信息安全已经成为国际上研究的热门课题。本文立足于国内外该领域的先进成果,充分结合数学、密码学、信息论等相关学科的知识,主要探讨了有关数字图像信息安全的加密技术。从背景、发展、现状和应用等方面阐述了数字图像加密技术并对其进行了归纳和分类,此外文中提出了基于现代密码体制的加密方法,给出了评价置乱加密效果的量化计算式,最后以一种商业票据的防伪算法具体实践了图像加密在数字水印中的影响和作用。 本文主要工作可分为如下四部分: 1 数字图像加密技术的方法综述:从相关文献来看,数字图像加密的方法有很多种。本文具体详细地总结了现有的图像加密方法及其特点,并对其进行了分类和规整,试图为今后寻找合适的图像加密方法提供一些参考信息。 2 基于现代密码体制的数字图像加密算法:现代密码体制对一维信号提供了良好的保密基础,而数字图像最终在传输信道上也转化为一维二进制流。可见,现代密码体制适用于数字图像保密。本文在研究现代密码体制的基础上,试图将其应用于数字图像加密上来,提出了一种基于数据加密标准DES的图像加密算法。实验表明了该算法的可行性,算法能够抵抗如局部破坏等一定程度的攻击,其良好的雪崩效应更增加了该算法的优势。 3 数字图像置乱加密技术及其效果分析:置乱加密是数字图像加密技术中的热点问题。算法的优劣直接影响其安全性及其它处理的效果。本文讨论了现有的置乱加密方法,并结合图像处理中常用的基本统计量,提出了一种基于纹理特征的置乱加密效果的量化评价,定义了一种新的置乱度。该置乱度计算量小,从纹理结构上反映置乱效果,测试数据和人的视觉较一致,可满足一定的度量标准,适用作置乱效果的定量分析。 4 置乱加密技术在数字水印中的应用研究:理论上,良好的数字图像置乱加密技术可以有效地分散比特信息。本文详细分析了置乱加密技术在数字水印预处理中的作用,提出了图像加密技术在商业票据水印防伪中的实际应用算法。该算法能够抵抗票据使用过程中的打印和扫描,图像置乱加密技术确保了在票据破损的情况下,能够恢复出水印信息。更多还原

【Abstract】 Nowadays, the information security of digital image has already become the international hot subject. Based on the advanced achievement in this field, this thesis discusses mainly the encryption technology in the security of digital image by using mathematics, cryptography, information theory etc. Firstly it explains the background, development, current situation and application of the digital image encryption technologies, which are summarized and classified. Secondly the thesis proposes a novel method of image encryption that is based on modern cryptogram system, and a formula that can evaluate the encryption result. Finally it uses the anti-counterfeit algorithm for commercial bills to practice the effect and influence of the digital image encryption in the digital watermarking.The details of the thesis are as follows:1. The summarization of the digital image encryption methods: According to the relevant papers, there are many kinds of the digital image encryption methods. By classifying these encryption methods and their characteristics, the thesis tries to offer relevant information for searching more suitable encryption methods.2. The digital image encryption algorithm based on modern cryptogram system: Modern cryptogram systems have offered a good cryptic foundation to the one dimension digital signal, and the digital image is finally turned into one-dimensional binary data when transmitted. In principle, the methods of modern cryptogram system are suitable for the digital image encryption. On the basis of studying modern cryptogram system, this thesis tries to apply it to encrypt the digital image. A digital image encryption algorithm based on DES is proposed in the thesis. The experiment shows the feasibility of the algorithm. What is more, it is robust to anti-attack tests such as partly-destroyed attack. Favorable avalanche effect increases the advantage of the algorithm even more.更多还原