对OPA密写的检测和增强安全性的调色板图像密写方案

在以调色板图像为载体的密写方法中,最佳奇偶分配(OPA)是一种失真小,因而隐蔽性较好的方法.本文首先指出OPA方法仍存在安全漏洞,因为经OPA密写的图像中存在一些特殊的颜色,这些颜色只能被修改为其它颜色,其它颜色却不能改为这些颜色,分析者可根据这些特殊颜色察觉秘密信息的存在.本文提出一种新的调色板图像密写方法,既保留了OPA失真小的优点,又不存在可被密写分析者利用的奇异颜色.另外,本文还考虑了调色板图像密写的另一个安全漏洞,即由调色板图像生成二值图像并检测其混乱程度可暴露其中是否含有密写信息.根据原始图像局部特性进行自适应嵌入可进一步提高系统的安全性,使这种基于二值图像的分析方法也不能奏效.

Detection of OPA Stego-Data and Secure Steganography in Palette Images

Although distortion caused by the optimal parity assignment (OPA) steganography is very small,it is not secure enough due to the existence of some peculiar colors.No other colors can be modified into these colors in data embedding.This paper proposes a new steganographic scheme that,while keeping the advantage of low distortion of the OPA,avoids the above-mentioned peculiar colors so that steganalysis based on the exploration of these colors is defeated.In addition,existence of stego-information in a palette image may often be revealed through observation of a generated binary image that,due to the randomness of the embedded data,exhibits no correlation with the host image.Making use of the local properties in the host image so that the chaotic degree is reduced,this security flaw in many steganographic techniques using palette images is removed.