Insight into collusion attacks in random-grid-based visual secret sharing

Visual secret sharing (VSS), either visual-cryptography-based (VC-based) VSS or random-grid-based (RG-based) VSS, is a well-known technology of secret communication for sensitive security applications. Horng et al. (2006) kindled the interest in the cheating problem existing in threshold VC-based VSS. The cheating problem happened when dishonest participants collude to cheat honest ones by enabling the latter to accept the wrong secret information generated by the former. As RG-based VSS (RGVSS) has gained significant attention in academia in the past years, it is concerned that RG-based VSS may also suffer cheating attacks. The authors of the present study demonstrate that the security risk does exist in RG-based VSS. To prove the feasibility of cheating, the experimental results and formal analysis illustrate that the proposed collusion attacks do work.

► RG-based VSS (RGVSS) has gained significant attention in academia in the past years.
► It is concerned that RG-based VSS may also suffer cheating attacks.
► The authors of the present study demonstrate that the security risk does exist in RG-based VSS.