Novel Stream Cipher Using 2-D Hybrid CA and Variable Ordered Recursive CA Substitutions

This paper presents a new stream cipher for data security, which is based on the replacement of data values using variable ordered recursive cellular automata (CA) substitutions. To achieve this aim, 2-D hybrid CA was built firstly, then 1^st-ordered and 2^nd-ordered generalized CA transforms were developed to build variable ordered recursive CA substitutions. The proposed stream cipher satisfies the properties of confusion and diffusion because of the proposed CA substitutions are flexible. Moreover, the characteristics of the proposed stream cipher are loss-less, symmetric private key, very large number of security keys (number of possible security keys is more than 10²⁷⁴), and key-dependent pixel value replacement. Simulation results obtained using some color images clearly demonstrate the strong performance of the proposed stream cipher.