基於視覺密碼的改良式多機密影像分享機制

An Improved Sharing Multiple Secret Images Scheme Based-on Visual Cryptography

許詔勛(Chao-Hsun Hsu)

指導教授 ： 涂世雄

中原大學/工學院/電機工程研究所/碩士(2010年)

https://doi.org/10.6840/cycu201000668

摘要

摘要
在本論文中，我們提出一個方法，在分享多機密影像視覺密碼時，可以有效的改善投影片資源的利用。我們考慮到多機密影像，對所有的機密影像產生一個主金鑰，相對的我們使用主金鑰去分享機密影像並得到多機密分享影像。我們合併這些分享影像結合成一個影像，接著我們調整主金鑰並產生一個新的金鑰。當新的金鑰疊合在結合的分享影像上不同的位置時就會顯示不同的機密影像。
在提出的方法中，我們使用傳統{2,2}視覺密碼模型來加密。利用水平或垂直的方式去結合分享影像，根據機密影像數量的不同，可以隱藏兩張到四張的機密影像並且可以有效的減少儲存空間。我們的方法分成兩類，第一個方法是將金鑰疊合在結合分享影像上便可產生機密影像1，當金鑰移動到底部機密影像2就會顯現出來。在這個方法中，我們使用交錯的加密方式來節省資源。第二個方法只要將金鑰與結合的分享影像疊合，並旋轉金鑰的方向，就可以得到四個不同的機密影像。在此方法中，我可以有效的減少分享影像的大小。
我們提出的方法有下列幾點貢獻：
1. 我們只需要兩張分享影像，即可隱藏兩到四張的分享影像。
2. 可以有效減少儲存空間、透明投影片與碳粉的使用量，響應節能減碳。

我們相信本論文的研究結果對未來視覺密碼學的相關研究上能有更進一步的改良發展且在應用上能有相當的助益。

關鍵字

視覺密碼

並列摘要

Abstract
In this thesis, we propose a scheme for sharing multiple secrets that it can effectively to improve the resource saving scheme on visual cryptography. In our scheme, the multiple secrets are taken into consideration, and a master key is generated for all the secrets; correspondingly, we share each secret by using the master key and obtain the multiple shares. Then, we merge these shares into a combined share, and adjust the master key to generate a new key. The secrets are revealed when the key is superimposed on the combined share in different locations using the proposed scheme.
In our proposed scheme, the encryption process is performed by using traditional {2, 2} visual cryptography scheme. The sharing images are combined by using horizontal or vertical method. According to different quantity of secret images, we can hide 2~4 secret images and effectively reduce the storage. The proposed scheme is divided into two categories. For the first case, when the key is superimposed, one secret appears; when the key is shifted down to the bottom, the other secret is revealed. Hence, we save the storage resource by using staggered encryption. For the other case, we superimpose the key and the merged share, and we turn the angle of the key. Finally we will get four different secret images. In this case, the size of the shared images can be greatly reduced.

The contributions of our research are as follows：
1. In traditional visual cryptography, two share images can only be hidden one secret image. But in our proposed scheme, we can hide two to four secret images with two share images.
2. We can avoid wasting a lot of storage and reduce amount of transparencies and black toner to reach to Energy Saving and Carbon Reduction purpose.
As expected, visual cryptography will be employed in future. We trust that results of our research in this thesis will be probably practical and efficient to establish a useful visual cryptography scheme with above advantages in applications.

並列關鍵字

Visual Cryptography

參考文獻

[4] 倪明輝，“以影像統計資訊為基礎之強健性空間浮水印技術” ，中原大學電

[7] 呂晏君，“應用互斥或運算於全彩機密影像之分享” ，淡江大學資訊管理學

[2] 羅志平，“A Study of the Robustness of Watermark” ，淡江大學電機工程學

[9] Amalfi, Italy, “Visual cryptography II: Improving the contrast via the cover

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