NEW PARADIGM IN GRAPH-BASED VISUAL SECRET SHARING SCHEME BY ACCEPTING REVERSAL IN BLACK-WHITE IMAGES

摘要

The visual secret sharing scheme (for short the VSS scheme) with access structure based on graph has been proposed as one of the (2, n)-threshold visual secret sharing schemes. Ateniese et al. showed a decomposition method into star graphs from a given graph which edges are specified by qualified sets, that is, two different participants (two vertices in the graph) have a common edge if and only if they can decrypt the secret image by stacking each share images. In this paper, we expand the definition of black-white visual secret sharing scheme and propose new decomposition methods by splitting complete n-partite graphs. These methods improve contrast of the decoded secret image. Moreover, we obtain several optimal examples and evaluate on graph-based VSS schemes.