In this paper, a new scheme for image encryption is presented. The scheme is based on a chaotic map and cellular automata (CA). CA is a collection of cells arranged in a grid, such that each cell changes state as a function of time according to a defined set of rules that includes the states of neighboring cells. The major disadvantages of cellular automata in cryptography include limited number of reversal rules and inability to produce long sequences of states by these rules. In this paper, reversible cellular automaton is presented and used to solve this problem. The presented scheme is applied in three individual steps. Firstly, the image is blocked and the pixels are substituted by a reversible cellular automaton. Then, image pixels are scrambled by a chaos map that is produced by an elementary cellular automata and finally the blocks are attached and pixels are substituted by an individual reversible cellular automaton. Due to reversibility of used cellular automata, decryption scheme can reversely be applied. The experimental results show that encrypted image is suitable visually and this scheme has satisfied quantitative performance.
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