一種保持直方圖特性的JPEG圖像掩密算法
A Steganography Preserving the Property of the Histogram for JPEG Images
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摘要: 傳統(tǒng)的JPEG圖像掩密算法往往因?yàn)楦淖兞溯d體圖像的DCT系數(shù)直方圖而不能抵抗各種基于直方圖的攻擊，或者為了矯正直方圖而降低了隱藏容量，該文提出一種新的保持直方圖特性的算法。該算法在嵌入秘密消息時(shí)，動(dòng)態(tài)建立Adjust_info表記錄系數(shù)直方圖被改變的情況，然后根據(jù)該表調(diào)整系數(shù)的變化方向，這樣不但可以補(bǔ)償直方圖的改變，而且并不降低隱藏容量。對(duì)多幅圖像的實(shí)驗(yàn)表明，該算法不但能夠達(dá)到13%的高隱藏容量(壓縮因子為75)，而且掩密后圖像總體DCT系數(shù)直方圖的平均失真率為0.81%。由改進(jìn)算法掩密后圖像低頻DCT系數(shù)直方圖的最大失真率為3.83%，平均失真率只有1.98%，僅對(duì)直方圖做了微小的改變，因此可以有效抵御各種直方圖攻擊，從而為安全掩密提供了可靠保證。
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關(guān)鍵詞:
- 掩密技術(shù);掩密分析技術(shù);JPEG圖像;直方圖特性;直方圖攻擊
Abstract: Traditional steganographic techniques for JPEG images always suffer from histogram-based attacks because they change the DCT coefficient histogram of the cover image, or from the reduced hiding capacity due to the correction of the change of the histogram. A new steganography preserving the property of the histogram is proposed in this paper. When the secret message is embedded, an adjust_info table is built to memorize the alteration of the histogram. Then the modification direction of the coefficient is adjusted according to the table. In this way, the change of the histogram is compensated and the hiding capacity is not reduced yet. Several experimental results demonstrate that the algorithm can attain a high hiding capacity of 13% (the quality factor is 75). Furthermore the average distortion rate of the general DCT coefficient histograms on stego-images is 0.81%, the maximal distortion rate of the histograms on low frequency coefficients is 3.83% obtained from the stego-images generated by the improved algorithm and the average distortion rate of them is only 1.98%. The property of the histogram is fine changed; therefore, various histogram-based attacks can be effectively resisted and secure steganorgraphy can be insured. -
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