An Application of Keystream Using Cellular Automata for Image Encryption in IoT

Abstract

Recently, there have been some studies on security applications using cellular automata. A cellular automaton (CA) is characterized by simplicity and high-speed computation, making it suitable for the resource-constrained IoT environment. In this paper, we first merge a sliding-window, bit permutation, and a CA and propose a keystream generator that has the inherent CA advantages of simplicity and speed. The sliding-window provides the unpredictability of the keystream and gains strength in terms of security. The produced keystream has passed the tests of NIST SP800-22. On the basis of the proposed sliding-window CA keystream generator, an image encryption system is further proposed. We use the keystream generated to scramble and confuse the original image. The histogram of the encrypted image is more average. It can resist differential attacks, and in the differential attack analysis, the NPCR and UACI values are at least 99% and 33%, respectively.