Abstract: Based on constant weight code constructed from steiner system, a (2,n) visual cryptography scheme is proposed through research on the relation between constant weight code and (2,n) visual cryptography scheme. The design method is proposed in process of the scheme’s existence proof. The scheme can balance performance between pixel expansion and contrast much better as contrast to existing schemes. Experimental results demonstrate that pixel expansion decreases greatly and contrast is closing to maximum in the scheme.

Key words: visual cryptography scheme, constant weight code, secret sharing, threshold scheme

摘要： 通过研究恒权码与(2,n)视觉密码方案的关系，利用steiner系统构造恒权码，提出了基于恒权码的(2,n)视觉密码方案，在证明其存在性的同时，给出了该方案的构造方法。与现有方案相比，能较好地折衷像素扩展度和相对差。实验结果表明，该方案在保证相对差接近极大值的前提下，大大降低了像素扩展度。

关键词: 视觉密码, 恒权码, 秘密分享, 门限方案

CLC Number: 

• TP393.08