建立在以量化為基嵌入技術上之數位影像藏密法

A Digital Image Steganographic Scheme Based on Quantization-Based Embedding Technique

楊士鋒(Shih-Feng Yang)

《環球科技人文學刊》 18期 (2014/03) Pp. 23-34

摘要

藏密法（steganography）為資訊隱藏（information hiding）技術的一種應用，希望藉由將機密訊息藏入掩護媒體（cover medium）中不被發現，來達到秘密通訊之目的。本文提出了利用量化為基嵌入技術（quantization-based embedding technique）所設計出，以數位影像做為掩護媒體之藏密法。在使用量化為基嵌入技術所設計出之數位影像資訊隱藏法來隱藏機密訊息時，使用之量化步距（quantization step size）越小，掩護影像（cover image）之失真程度越低。而本文所提出之方法，在原本之量化步距外，額外再導入一個可調整控制之參數，以進一步降低掩護影像之失真程度。實驗結果顯示，藉由此新導入之參數，的確可在選定量化步距後，進一步降低掩護影像之失真程度。惟需注意的是，偽裝影像之直方圖，可能會因為此新導入參數數值之不同，而出現不同程度之尖刺狀圖形，導致偽裝影像較難以抵抗以直方圖為工具所進行之偵測攻擊。

關鍵字

資訊隱藏 ； 藏密法 ； 量化為基嵌入技術 ； 數位影像

並列摘要

Steganography is one of the applications of information hiding techniques. The purpose of steganography is to transfer messages secretly by embedding messages into cover media to conceal the very existence of the messages. In this paper, a digital image steganographic scheme is presented. The steganographic scheme is based on quantization-based embedding technique and uses digital images as the cover medium. In using digital image information hiding schemes based on quantization-based embedding technique to hide secret messages, the distortion of cover images will be smaller if a smaller quantization step size is used. Besides the quantization step size, the scheme presented in this paper incorporates an additional adjustable parameter to further decrease the distortion of cover images. Experimental results show that the new incorporated parameter can indeed further decrease the distortion of cover images under a selected quantization step size. However, it should be noted that because of the selection of different values of the new incorporated parameter, different types of spikes may appear in the histograms of stego-images leading to a decrease of the ability of stego-images against detection attacks based on histogram analysis.

並列關鍵字

information hiding ； steganography ； quantization-based embedding technique ； digital image