标题: 新视觉化密码编码法的分析
The Analysis of New Visual Cryptography Scheme
作者: 邱善福
Shan-Fu Chiou
曾文贵
Wen-Guey Tzeng
资讯科学与工程研究所
关键字: 视觉化密码;视觉化密码编码法;秘密分享;visual cryptography;visual cryptography scheme;secret sharing
公开日期: 2000
摘要: 视觉化密码(visual cryptography)是指一种把秘密图像编码成秘密图像分享的编码法,在每个参与者拥有一份印有秘密图像分享的投影片时,让某些合乎资格(qualified)的参与者,可以透过“视觉”直接地回复秘密图像,而无需拥有任何密码学相关的知识,也无需任何的运算;但是,对于限制资格(forbidden)的参与者来说,不管透过任何方法,都无法从手中的秘密图像分享,得到任何关于秘密图像的资讯。
由于先前视觉化密码的定义,几乎都局限于单调(monotone)的情况,而且,定义上也有不合理的地方,举例来说,在叠合投影片后,秘密图像都比周围背景的颜色为深。而实际上,只要有对比存在,不管秘密图像是比周围背景的颜色深或浅,我们都可以透过视觉系统分辨出来。而新的定义便修正了上述不合理的地方,也较原先的定义更适用于一般的情况。
本篇论文就基于新视觉化密码的定义,对新的定义做性质方面的讨论,提出一套能让建构的过程更有效率的编码方法,并在两种定义下,比较其对于相同的存取结构(access structure)的编码效果。
Visual cryptography is a method to encode a secret image into some secret image shares. Each participant receives a transparency that is printed some secret image share. Certain qualified subsets of participants can “visually” recover the secret image directly without knowing any knowledge of cryptography and performing any computations, but other sets, called forbidden sets, of participants have no information about the secret image, even to any cryptanalyst.
The conventional definition of visual cryptography is limited to monotonic situation, and it is unreasonable about the part of “contrast”, for example, the recovered secret image is always darker than background after stacking transparencies, but we know that this is not necessary. No matter the recovered secret image is darker or lighter than background, we can recover the secret image by human visual system. New definition corrects this and makes it more general than conventional one.
Based on the new definition, in this paper, we study the properties of new definition, propose a more efficient construction method, and show some results about comparison of two definitions.
URI: http://140.113.39.130/cdrfb3/record/nctu/#NT890394094
http://hdl.handle.net/11536/66999
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