Robust Cheat-prevention for Random Grids Based Visual Secret Sharing Scheme

In conventional visual secret sharing (VSS), a secret image is encrypted into noise-like random-looking shares, a subset of which when stacked together reveal the secret. Random grids (RG) eliminate pixel expansion and extensive codebook designs of conventional VSS. However, like conventional VSS, RG-based VSS are prone to collusion attacks. Existing cheat-prevention algorithms reduce the probability of collusion attacks, but these do not consider issues arising due to noise-like nature of the shares. We introduce two issues that may lead to false accusations and we devise a robust cheat-prevention algorithm to tackle these. Experimental results validate the efficacy of the algorithm.