Novel Stream Cipher Using SCAN and Variable Ordered Recursive CA Substitutions and Its DSP+FPGA Implementation

This paper presents a new stream cipher for data security, which is based on permutation of the data and replacement of the data values. Permutation is done by scan patterns generated by the SCAN approach. The replacement of data values using variable ordered recursive cellular automata (CA) substitutions. To achieve this aim, an encryption-specific SCAN technique was firstly developed, 2-D hybrid CA was next built, and then 1-ordered and 2-ordered generalized CA transforms were introduced to build variable ordered recursive CA substitutions. The proposed stream cipher satisfies the properties of confusion and diffusion because of characteristics of the SCAN and the 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 9568 10 ~ 14785 10 according to the size of the 2-D von Neumann CA), and key-dependent pixel value replacement. Experimental results obtained using some color images clearly demonstrate the strong performance of the proposed stream cipher. This paper also shows the DSP+FPGA implementation of the proposed stream cipher for the real-time image security.