一個機密影像分享演算法的實作

Implementation of A Secret Image Sharing Algorithm

鄭弘倫(Hung-Lun Cheng)

指導教授 ： 陳朝欽

國立清華大學/電機資訊學院/資訊系統與應用研究所/碩士(2010年)

摘要

In this thesis, we implement a (k, n) secret image sharing algorithm based on Thien and Lin’s scheme with modifications to reduce some distortion. The secret image is processed and split into n shadow images. We can reconstruct the secret image by using Lagrange interpolation when we collect k or more shadow images. Firstly, we propose an elegant method using the concept of generators in a multiplicative cyclic group to shuffle the secret image. The security is based on the difficulty of solving the discrete logarithm problem. We also present a truncated method to reduce the truncation distortion. We replace zero points in the range [0, 250] with those grayscale of pixels greater than 250 with positions of zero occurrences under 251. Experimental results show that the proposed method can suffer from the truncation distortion while preserves the security.

關鍵字

機密影像分享 ； 門檻值 ； 循環群 ； 直方圖

參考文獻

[Chan2008] C.C. Chang, Y.P. Hsieh, and C.H. Lin,” Sharing secrets in stego images with authentication,” Pattern Recognition, vol. 41, no. 10, 3130-3137, 2008.

[Chen2009] C.C. Chen, C.C. Chen, and Y.C. Lin, “Weighted modulated secret image sharing method,” Journal of Electronic Imaging, vol. 18, no. 4, 1-6, 2009.

[John1998] N.F. Johnson and S. Jajodia, “Exploring steganography: Seeing the Unseen,” IEEE Computer, vol. 31, no. 2, 26-34, 1998.

[Lin2003] C.C. Lin and W.H. Tsai, “Visual cryptography for gray-level images by dithering techniques,” Pattern Recognition Letters, vol. 24, no. 1-3, 349-358, 2003.

[Lin2004] C.C. Lin and W.H. Tsai, “Secret image sharing with steganography and authentication,” Systems and Software, vol. 73, no. 3, 405-414, 2004.