一种同态加密域图像可逆水印算法  

A Novel Reversible Image Watermarking Algorithm in Homomorphic Encrypted Domain

作　　者：项世军[1] 罗欣荣[1] 石书协 

机构地区：[1]暨南大学信息科学技术学院,广州510632

出　　处：《计算机学报》2016年第3期571-581,共11页Chinese Journal of Computers

基　　金：国家自然科学基金(61272414)资助~~

摘　　要：可逆水印技术是一种能够在提取水印信息后无失真地恢复出原始载体内容的信息隐藏技术,在军事和医学等对载体内容保真度要求较高的领域中具有很好的应用前景.当原始载体内容涉及个人隐私时,载体所有者不希望其直接暴露在传输信道中.因此,该文提出了一种基于Haar-DWT(Haar-Discrete Wavelet Transform)的同态加密域中的图像可逆水印技术:(1)通过利用数据搬移及量化的方法,分别解决了Haar-DWT过程中可能遇到的负数问题和小数问题,实现了加密域的整数Haar-DWT;(2)在保证逆变换系数为整数的前提下,将水印嵌入到k层高频子带中,得到的密文结果与明文域处理的结果一一对应,很好地实现了同态加密域中基于Haar-DWT的图像可逆水印;(3)能够利用乘法逆元MIM(Multiple Inverse Method)的方法,完全移除扩展因子,大大降低了加密域中的数据扩展.实验结果表明该文算法具有较大的嵌入容量,嵌入率最高可达到0.25bpp,而对应的峰值信噪比平均可达39dB.据作者了解,该文提出的图像可逆水印算法在同态加密域尚属首创.Reversible watermarking is a technology which can perfectly recover the content of original carrier after the watermark is extracted. It is a potential technique in applications of military and medical image. When the contents involve privacy, the owner doesn＇t want to expose them to the public channel To this end, we propose a reversible image watermarking algorithm in homomorphic encrypted domain by using Haar-DWT （Discrete Wavelet Transform）; （1） Employing the representation of the negative and decimal values in encrypted domain correspondingly, the integer Haar-DWT is implemented directly for the encrypted image; （2） A reversible image watermarking algorithm in homomorphic encrypted domain is successfully implemented by analyzing inverse transform of Haar-DWT, embedding watermark data into the high frequency sub-band and keeping all the coefficients after the inverse transform as integer values; （3） The expanding factor can be totally removed by employing the MIM （Multiple Inverse Method） and the water-marked image in encrypted domain has less data expansion. The experimental results demonstrate that the proposed algorithm has a superior performance in the PSNR values and embedding capacity （0. 25 bpp with 39 dB on average）. To the best of our knowledge, there has been no report on the reversible watermarking scheme in homomorphic encrypted domain.

关 键 词：整数Haar-DWT 同态加密 可逆水印 数据扩展 大容量 

分 类 号：TP309[自动化与计算机技术—计算机系统结构]