Optical encryption based on 3-D sphere and phase retrieval in gyrator transform domain

With the rapid development of modern technologies, information security has attracted more and more current attention. In this paper, we present optical image encryption based on 3-D sphere and phase retrieval in gyrator transform domain. The plaintext is divided into a series of small quadratic blocks, and each block is treated as a particle. The series of particles is distributed in 3-D spheres, and is encrypted into one phase-only mask based on an iterative phase retrieval algorithm. During image decryption, the extracted phase-only mask is rotated and illuminated to sequentially extract a series of focused particles. Subsequently, a decrypted image can be obtained by incorporating all the decoded particles in the transverse domain. Numerical experiment is conducted to demonstrate feasibility and effectiveness of the presented method.