Image encryption using hybrid structured phase mask and hybrid mask based on affine and Fresnel transforms

Abstract

An asymmetric cryptosystem is proposed for securing of double image encryption using hybrid structured phase mask and hybrid mask in affine transform and Fresnel transform domain. The structured phase mask used is a combination of Radial Hilbert mask (RHM) and Fresnel Zone plate (FZP) and the hybrid structured phase mask is a hybrid of phase masks and secondary images after taking Fourier transform (FT) which increases the number of parameters and key length. Hence it helps in enhancement of security against attackers. Affine transform is for inserting randomness in the original images which act as additional key for the proposed work. The encoding and decoding are done by using different keys. The results are carried out by the help of MATLAB R2018a. For the proposed work, Mean Square error (MSE), Peak signal to noise ratio (PSNR) is calculated. The statistical outcome Entropyis also evaluatedwhich ensures that the proposed technique is relevant.