An improved method to enhance the security of double random-phase encoding in the Fresnel domain

Optical encryption technique based on double random-phase encoding in the Fresnel domain (named as FrDRPE) has been shown to be vulnerable to the chosen-plaintext attack owing to the linear property of the Fresnel transform. To negate such an attack, different phase-masks (i.e. part of the encryption keys of FrDRPE) are used in our system to encrypt different plaintexts while the number of the transmitted keys is not increased. In this case, a plurality of plaintext–ciphertext pairs corresponding to the same encryption key that are needed in the chosen-plaintext attack cannot be acquired by our improved system. Accordingly, this system can successfully resist the chosen-plaintext attack. Some numerical simulations are performed to validate the feasibility of our proposed scheme.

► We improve the double random-phase encoding in the Fresnel domain.
► Chosen-plaintext attack is invalid for our proposed system.
► Number of the transmitted keys is reduced extremely.
► Addition of the amplitude mask enhances the security of our designed system.