Robust multidepth object encryption based on a computer-generated hologram with a cascaded structure

A robust, asymmetric, multidepth, three-dimensional object encryption scheme based on a computer-generated Fresnel hologram in the cascaded fractional Fourier domain is proposed. A layer-based Fresnel transform is used to generate a computer-generated hologram, which is then decomposed into two phase-only masks with a random phase distribution using matrix composition and decomposition methods. Encryption is implemented by using the created phase-only masks in two cascaded fractional Fourier transform domains, and a pair of private keys is generated in the encryption process. The cryptosystem is asymmetric and possesses high resistance against various potential attacks, such as brute-force, chosen-plaintext, known-plaintext, and ciphertext-only attacks. The simulation results and cryptanalysis confirmed the feasibility and effectiveness of the proposed encryption scheme.