A cheating-prevention mechanism for hierarchical secret-image-sharing using robust watermarking

Secret image sharing (SIS) techniques allow visual secrets to be shared between multiple people. These techniques require a predetermined access structure to be satisfied to reveal the secret. SIS schemes have the potential to increase security in several applications including telemedicine and image transfer in the cloud computing environment, providing controlled access to confidential images. To date, a significant number of SIS schemes with various properties and access structures have been proposed. Among them, hierarchical SIS (HSIS) is considered foremost since almost all organizations and associations manage their secret information in a hierarchical manner. However, the HSIS scheme tends to suffer from security flaws as the secret image can often be visually leaked, even when the access structure is not properly satisfied. To avoid this security flaw, we propose a cheating prevention mechanism by introducing a robust watermarking technique based on the Quantization Index Modulation-Dither Modulation (QIM-DM) algorithm in the discrete cosine transform (DCT) domain. Experimental results demonstrate the superior effectiveness of our proposed cheating prevention mechanism. Furthermore, our approach retains all of the desirable properties of the HSIS scheme.