Optical image encryption based on multiple-region plaintext and phase retrieval in three-dimensional space

Recently, three-dimensional (3D) phase retrieval algorithm has been developed for optical image encryption to overcome the limitations inherent in conventional two-dimensional (2D) phase-retrieval-based optical cryptosystems. In this paper, we propose a novel method for optical image encryption based on multiple-region plaintext and phase retrieval in 3D space. The plaintext is divided into multiple regions, and each region is encrypted into one phase-only mask based on phase retrieval in 3D space. The plaintext can be encrypted into multiple independent phase-only masks (i.e., ciphertexts) during image encryption, and cryptosystem security is effectively enhanced. Numerical experiment is conducted to demonstrate feasibility and effectiveness of the proposed method.