Image encryption based on non-affine and balanced cellular automata

• The entire encryption process is completed by both reversible and irreversible CA.
• The reversible CA is responsible for confusion and diffusion processes.
• The irreversible CA is used to generate pseudo-random key stream sequence.
• Non-affine and balanced rules are adopted for CA to obtain good properties.

On the basis of the analysis and classification of the 256 elementary cellular automata, a kind of non-affine and balanced cellular automata with complex behavior are used as basic blocks in an image encryption scheme. In this scheme, the diffusion operation is performed by the local interaction among cells, while the confusion operation is achieved by the nonlinear and balanced rules applied to cells. As a result, confusion and diffusion are well integrated. Experimental results show that the proposed image encryption scheme has a lot of characteristics, including large key space, low correlation of adjacent cipher pixels, and high sensitivity to the plaintext and key, which can effectively protect the security of the encrypted image.