具有冗余度的抗干扰文本伪装算法

【作者】 王丹丹；

【导师】 蔡翔云；

【作者基本信息】 昆明理工大学 ， 系统理论， 2007， 硕士

【摘要】 随着计算机技术和因特网技术的飞速发展,数字作品的传播达到了前所未有的深度和广度,其版权保护也正成为一个迫切需要解决的问题。数字水印是近十年来出现的一种有效的数字产品版权保护技术。它克服了传统密码学技术中加密的内容在解密之后不再安全的问题,因而作为知识产权保护和数字多媒体防伪的有效手段,正得到广泛的研究与应用。目前,基于图像、视频和音频的数字水印研究成果很多,并且很多方法是比较有效的。但是这些方法都不太适用于文本文档的规则结构。迄今为止,基于文本的数字水印研究因其特殊性,相关的研究成果主要集中在基于文本的格式方面,即通过对文档的格式作一些微量调整,将信息以二进制编码的形式隐藏于文本对象的变动中。这类算法由于完全信赖于文本格式(行移、字移、特征编码等),均存在抗攻击性不够强,鲁棒性较差,容量较小的缺点。究其原因,主要是因为水印信息只能加入文本内容之外或基于文本内容。为了提高秘密文本在传输过程中的安全性,加大水印容量,本文在文本伪装算法的基础上改进提出了一种具有冗余度的抗干扰文本伪装算法。本算法利用小波分析的多分辨特性,将秘密文本在小波域进行变换,它将不具有冗余度的文本信号变为具有冗余度的信号,再对冗余信号进行文本的伪装。算法基于Matlab平台处理文本数据,Delphi平台编制的水印程序进行实验,重点针对水印的容量、鲁棒性、抗干扰、隐蔽性这四个指标进行了大量的水印嵌入、提取和攻击实验,验证了本文的数字水印方法具有较好的隐蔽性、鲁棒性、抗干扰能力以及较好的容量性能。本文提出的具有冗余度的抗干扰文本伪装算法不但可以实现用一段普通文本和图像来掩饰秘密文本的传输,突破了现有水印方法中容量不足、鲁棒性较差的难题,对解决目前文本文件安全难以控制的问题是一个有益的尝试,对文本水印领域的研究和发展有着一定的意义。更多还原

【Abstract】 The rapid development of computer and Internet technology has led to digital products being distributed deeply and widely to a previously unpredicted level. Meanwhile, their copyright protection is a pressing problem. Fortunately Digital Watermarking has become an effective method of copyright protection for digital products in the last ten years. It has solved the problem of traditional cryptography that encrypted contents are not secure after decryption, therefore it has been studied and used widely as an effective method of knowledge copyright protection and preventing from sham for digital multimedia.There are now many published digital watermarking research papers covering image, video and audio documents, which demonstrate how effective these methods are. However these methods can’t be applied to the regular structure of text documents very much. Until now digital watermarking researches on text, have been focusing on the format of text documents because of their particularity. In detail these methods convert binary information into tiny changes in the format of text documents. These algorithms are vulnerable to attack and poor in robustness because they depend totally on the format of text documents, such as line-shift, word-shift and feature coding. Chiefly this is because the watermark data can only be embedded onto the text document’s or the text-watermarking algorithms based on the content of text documents.In order to improve the security of secret text during transmission processing, enlarge the capacity of watermarking. This article improved in the algorithm of text steganography, and statement a the algorithm of text steganography which has redundance and can antijamming. This algorithm based on multi resolution characteristics of wavelet analysis, The text become has the redundance signal again. The algorithm based on the Matlab platform processing text data, the Delphi platform establishment watermark procedure carries on the experiment. It aimed at the watermark with emphasis the capacity, robust, antijamming confidentiality these four targets has carried on massive watermark inserting, the extraction and the attack experiment, confirmed this article digital watermark method to have the good confidentiality, robustness, antijamming ability as well as the good capacity performance.This algorithm realizes conceals transmission the secret text with ordinary texts and the image, broken through in the capacity insufficiency, the robust bad difficult problem of the existing watermark method. It is a beneficial attempt to solves the problem which at present text document safe controls with difficulty has certain significance to the text watermark domain research and the development.更多还原