关键词: 可视密码, 可视秘密共享方案, 一般访问结构, 阈值方案

Abstract: Most recent papers about binary visual cryptography schemes are dedicated to study a higher contrast of recovered images or a smaller share size in visual secret sharing schemes.This paper proposes a new binary （k，n）-VCS based on the secret sharing schemes.A strong access structure is given which uses the feature of the solution of a system of linear equations over the binary field and hierarchical method for constructing basis binary matrices S⁰，S¹，and the （k，n）-VCS is obtained and in almost all the case a much smaller pixel expansion is gained from this method.

Key words: visual cryptography, visual secret sharing scheme, general access structure, threshold scheme