Cellular Automaton (CA) has been shown to be capable of generating complex and random patterns out of simple rules. There has been constant efforts of applying CA to develop ciphers, but the attempts have not been successful. This paper describes how repeated application of simple CA transfomr may be used to achieve confusion and difision, needed in block ciphers. The components have been evaluated for their mbusmess against conventional cryptanalysis and the results have been found to be comparable to standards. Finally, the parts are assembled in an unconventional way to construct a self-invertible CA based round, which is resistant against linear and differential cryptanalysis and yet can be eficiently implemented.