High-security image encryption by multiplexing phase encoding in domains of dual optical transforms

Abstract

A novel optical image encryption is proposed based on multiplexing of the random phase encoding after shift and rotation operations in domains of extended fractional Fourier transform (eFrFT) and Fresnel transform. The original image is subjected to eFrFT with the action of the random phase mask. The mask is shifted and rotated. The image obtained from the fractional Fourier transform is entered into Fresnel diffraction by the use of the phase mask to obtain the final encrypted image. We design that the multiplexing operation of the phase keys can reduce the storage volume of the keys. Here, the displacement amount, rotation angle and wavelength in this system can be used as additional keys to improve the security and reliability of the encryption system. Numerical experiments are conducted to verify the effectiveness and security of the algorithm. The results show that the keys are very sensitive enough for high security.