【作者】 蒋斌；

【导师】 平西建；

【作者基本信息】 解放军信息工程大学 ， 信号与信息处理， 2008， 博士

【摘要】 随着信息技术发展和应用的不断深入,信息安全越来越被世界各国所重视。信息隐藏技术是近年来信息安全领域的一个研究热点,它在数字媒体的版权保护,隐蔽通信等都有着广泛的应用。信息隐藏的两个主要技术分支即信息伪装和数字水印,其中信息伪装技术通过隐藏通信过程的存在来获得通信的安全性。信息隐藏的载体主要包括图像、视频、文本、音频等等,其中文本载体作为信息隐藏的一种重要载体类型,在人们工作生活中扮演着越来越重要的角色,文本载体中的产权保护、内容验证等安全问题也已成为人们必须考虑的重要问题。本文对文本载体信息隐藏以及隐写分析等相关技术进行了比较详细的研究与实践,主要研究内容和创新点如下:1.对文本载体的概念、范畴等做了阐释,明确文本载体信息隐藏的研究方向和内容,即文本信息隐藏和文本图像信息隐藏,对文本结构、冗余性、隐藏安全性做了理论的分析,建立了文本信息隐藏的理论基础。2.总结和分析了TXT、WORD、PDF等几种常见办公格式文本,以及HTML、XML、CSS、XSL等几种基于Web应用格式文本信息隐藏的各种方法,同时深入剖析这些文件的结构特点、冗余特性。3.针对WORD信息隐藏的特点,提出了一种基于字体缩放技术的WORD信息隐藏方法,该方法对WORD字体缩放比例进行编码,实现了单个字符嵌入3比特信息容量,并对秘密消息采用混沌序列加密,增强了算法的安全性。同时对实现WORD信息隐藏的两种方式即VBA技术和VC的Office自动化技术,从时间代价、难易程度等方面做了分析对比。4.将基于Web应用的文本载体信息隐藏作为重要的研究内容。利用级联样式表(CSS)文件描述RGB颜色值的不同编写方法,提出了基于颜色名称的CSS信息隐藏方法;根据CSS文本结构和规则编写方式,提出了基于规则结构的CSS信息隐藏方法,该算法在分析CSS规则编写特点基础上,从数学模型上建立CSS等价规则的多种定义,推导出相应的定理和推论,以此设计出基于CSS等价规则的嵌入和提取算法,实验结果表明该算法具有很高的嵌入容量和安全性;利用XML文本的结构特点和XSL转换XML过程中的方法特点,提出了基于XML查询重写的信息隐藏算法,该算法建立了路径查询自动机,利用修改XML路径查询结果,制定嵌入秘密消息与查询重写的相应规则,来实现信息隐藏。5.在详细分析了两种具有代表性的二值文本图像嵌入算法的优点和问题基础上,提出了一种新的基于分块的二值文本图像信息隐藏算法。该算法先对图像做分块处理,计算图像块特征值,选择视觉效果好的块作为嵌入的图像块,嵌入采用一种大容量的嵌入方法,对嵌入过程中存在的多个像素翻转选择,利用像素可翻转标准来做最优判定。实验结果表明该算法既提高了单个图像块中的嵌入容量,又保持了良好的视觉效果。6.分析了已有的二值文本图像隐写分析研究成果,对二值文本图像隐写分析做了有益的探索,提出了基于模式分析的二值文本图像隐写分析算法。算法提出了二值图像“模式”的概念,按照人体视觉的影响程度,将图像模式分成三类,建立了二值图像嵌入位置模式库,通过统计分析二值文本图像的模式在嵌入信息前后的变化特征,提出了基于模式分析的二值文本图像隐写分析算法,实验也证明该算法是一种性能较佳的检测算法。文章的最后,对本文工作进行了总结,并对文本载体信息隐藏及相关技术指出了研究方向。更多还原

【Abstract】 With the further development and application for information technique, information security has been absorbing much more attention by every country in the world. Information hiding has become a hot interest area in the research of information security, which has wide applications in many fields such as copyright protection of digital media, hidden communication. Steganography and watermarking are two main sub-disciplines of information hiding. Steganography is the art and science of communicating in a way which hides the existence of the communication.The carriers of information hiding mainly include image, video, text, audio and so on. Text carrier is acting as a more and more important role in people’s work and life, which is a very important carrier type in the information hiding. The property right protection and content validation of text carrier have been considered significant by people. Detailed researches and practice are completed in this paper on text carrier information hiding, steganalysis and other correlated techniques. The main works and creations are as follows:1. The conception and category of text carrier is explainded. The research direction of text carrier information hiding is oriented . The structure, redundancy and hiding security for text carrier are analyzed in theory, and the theoretical base of text carrier is founded.2. Some normal text carriers such as TXT, WORD, PDF, and other text carriers based on Web application for information hiding such as HTML, XML. CSS and XSL are summarized and analyzed. The structure and redundancy characteristics are deeply anatomized for those documents.3. A new information hiding algorithm based on font zooming for WORD is proposed. The algorithm coding for the scaling of WORD font, could embed 3 bits in each character. The algorithm increases the security from chaos sequence encryption for secret message. We made analysis comparison to the two ways of achieving information hiding for WORD, such as VBA and Office Automation technique for VC, by the side of time cost, difficulty extent etc.4. We take the information hiding for text carrier based on Web application as an important research content. A CSS(Cascading Style Sheet) information hiding algorithm based on color name is proposed, using the different compiling methods of describing RGB color for CSS document. A new CSS information hiding algorithm based on rule structure is proposed, according to CSS document structure and rule compiling mode. Some definitions about CSS equivalence rule are founded, some corresponding theorems and deductions are deduced on the basis of mathematics model, thus the embedding and extracting arithmetics are worked out, and the experimental results indicate this information hiding algorithm has quite large embedding capacity and security. A type of information hiding algorithm based on XML query rewriting is proposed, according to the structure characteristic of XML document and the XML translating method characteristic by XSL. The path query automaton is founded, and we constitute the rules between embedding message and query rewriting to achieve information hiding by modifying path query results for XML.5. A new information hiding algorithm based on partitioned for binary text image is proposed, on the basis of analyzing the virtues and questions of two representational embedding algorithm for binary text image in detail. The algorithm partition image into blocks firstly, then calculate the characteristic value for each image blocks, and choose fine vision image blocks as embedding blocks. The embedding method adopt a great capacity embedding method, utilizing pixel flippability criterion to determine the best flipping pixel where have several pixel flipping lacations to choose. The experimental results indicate this algorithm could not only increase capacity in each image block, but also preserve fine vision effect.6. Some beneficial explores are done about steganalysis for binary text image, a steganalysis algorithm based on pattern analysis for binary text images is proposed on the bases of analyzing existent research achievements. The“pattern”conception for binary image is put forward in the algorithm, and classify the patterns into three categories according to human vision extent, thus establish an embedding location pattern storeroom. The steganalysis algorithm based on pattern analysis is proposed based on statistic analyzing the changing characteristics of the patterns for binary text images before and after embedding messages. The experimental results indicate this algorithm is a fine detection algorithm.Finally, we summarize our research work, and indicate the research directions of information hiding and correlated techniques for text carrier.更多还原