【作者】 李光；

【导师】 车生兵；

【作者基本信息】 中南林业科技大学 ， 计算机应用技术， 2010， 硕士

【摘要】 信息隐藏技术作为一种既古老而又年轻的技术,已成为信息安全领域的一个重要组成部分,是现代社会迫切需要解决信息秘密传输的一种途径。其作为一门覆盖大范围科学领域的学科,涉及感知科学、信息论、密码学等多个学科领域,涵盖了对信号处理、扩频通信、图像处理等多种专业技术的研究。本文以文本信息隐藏技术为主题,跨学科的研究,提出了一种新颖的保护文本隐私和秘密的方法。先深入分析了现有文本信息隐藏技术的模型、分类、特性、典型算法；并且采用辨证方法,先分解再综合地对整个系统分为信息预处理过程和信息嵌入过程,在两个过程中分别做工作来提高系统的鲁棒性和透明性,而后综合设计出整套算法系统,并做仿真实验予以验证。在文本信息预处理过程中,文章深入分析了文本信息的特殊性和敏感性。本文拟采用为文本信息编码、容错控制和加密的手段对文字信号的预处理。本文提出了一种改进型Unicode编码,能解决多种字符的编码问题的,跨平台性能好；本文同时考虑到信息隐藏系统与通信系统的相似性,将文本信息隐藏问题等效为一个数字通信模型,应用数字通信中的信号编码中纠错编码进行容错设计来改善系统的稳健性；并且本文用一种复合混沌加密系统,不仅做到即使攻击者发觉也不能获取信息,同时还可以规避容错设计中码元具有统计规律的弊端。在信息隐藏过程中,文章分析并选择了最佳的数字图像作为文本信息隐藏的载体；由于文本信息冗余度小,相对常规算法有较大的隐藏容量；在信息隐藏的方法上,本文采用图像全局小波变换,避免视觉上的块状效应；并结合攻击特性使用并优化了中心极限定理；在信息隐藏的方式上,不仅在低频子带嵌入信息,而且同时在高频子带等多频带嵌入信息,重复嵌入信息,以规避有针对性的攻击；同时将秘密信息分段,分散了攻击目标,避免了统计分析。实验表明算法生成的载体图像透明性好,算法系统对噪声迭加、平滑滤波和JPEG压缩等常见图像处理操作,也具有较强的鲁棒性。特别是在知道其攻击方式的情况下,进行有针对性的嵌入和提取信息,以期得到正确秘密信息。算法系统信息隐藏容量大,并且在提取过程中无需原始图像,属于一种盲信息隐藏算法。更多还原

【Abstract】 Information Hiding as a technology both old and young, has become an important part of the field of information security, and it is an urgent need to address a way to transmit secret information security in modern society. As a cover a wide range of science disciplines, involving perception science, information theory, cryptography and other disciplines, covers the signal processing, spread spectrum communications, image processing and other specialized technology research.In this paper, the theme of the text information hiding interdisciplinary research, a new method of protection of privacy and confidentiality.Articles by dialectical method of decomposition first and then integrated the whole system is divided into information and information into the process, of pretreatment process.Separately in the two processes work to improve the system robustness and transparency, and then design a comprehensive set of algorithms systems, and experiments to verify.Preprocessing in a text message, the article in-depth analysis of the specificity and sensitivity of the text information. This paper adopted as the text encoding, fault-tolerant control and text signals encrypted by means of the pretreatment. This paper presents an improved Unicode encoding, can solve a variety of character encoding issues, cross-platform performance is well. Text information hiding system, taking into account the similarity with the communication system, the text information hiding problem is equivalent to a digital communication model to application of digital communication signals encoded in error correction coding for fault-tolerant design to improve the robustness of the system; In this paper, a complex and chaotic encryption system, not only even if an attacker finds that cannot get information, while also avoiding fault-tolerant design with statistical regularity symbol of the state.In the information hiding process, the article analyzes and choose the best digital image as a carrier of hidden text. Because text information redundancy small, relatively general algorithm has large hidden capacity; In the Information hiding methods, This article uses the global Wavelet transform, avoid Visual effects on the block. Combined attack of use and optimize the central limit theorem. In the way of information hiding, Embedded not only in the low frequency sub-band information, but also in the high frequency sub-band multi-band embedded information, etc. Repeat embedded information to avoid a targeted attack; while secret information section, dispersed targets, to avoid the statistical analysis.Experiments show that the resulting vector image transparency is good, the algorithm system on common image processing operation has the strong robustness. For example:noise superposition, filtering and JPEG compression, etc. Especially in the know its attack which targeted embed and extract information in order to get the correct secret information. This algorithm system has a large capacity of information hiding, and the extraction process without the original image, it is a kind of Blind Information Hiding Algorithm.更多还原