A recursive non-linear pre-encryption for opto-digital double random phase encoding

Abstract

In this paper, we propose a recursive non-linear pre-encryption to be carried out digitally on the input image in the spatial domain before applying any double random phase encoding (DRPE). It consists of firstly scrambling the input image chaotically and then performing the bit-wise XOR operation recursively between two consecutive pixels following a given pattern. The starting two consecutive pixels are formed by the initial pixel in the pattern and a random eight-bit integer. The proposed pre-encryption-based DRPE image encryption system and existing DRPE cryptosystems are compared in terms of the sensitivity of the various encryption keys to decryption attacks.