Unlike in the conventional DRPE scheme, here we have used a structured phase mask based on Devil's vortex Fresnel lens (DVFL) in the frequency plane  by multiplying the FrMT transformed image with phase function based on DVFL.
(iii) Multiply the transformed image by a structured phase mask based on (DVFL).
The keys of the proposed scheme include the order [alpha] of FrFT in the iterative process, the final phase key [phi](u, v), and the order p of the FrMT along with parameters of the structured phase mask, DVFL.
When even one incorrect parameter of DVFL is used, one can hardly retrieve the original image with other correct parameters.
Besides the decryption phase key obtained from the PRA, the proposed scheme also depends on some other factors such as the DVFL parameters, as well as orders of the FrMT and FrFT.