Experimental optical secret sharing via an iterative phase retrieval algorithm

The concept of threshold cryptosystem is fresh and rare in the field of optical information security. Based on a phase retrieval algorithm, we propose a novel threshold scheme with optical realization. In this method, a secret image is encoded into three phase-only masks (POMs), of which any two could recover the secret image but any single one could not. Besides, every POM is designed to be uniquely correlated with a pre-determined authentication image, which could be more easily authenticated than the POM. Numerical simulations and optical experimental results are provided to demonstrate the feasibility of the proposed method.