Stream cipher based on pseudorandom number generation with optical affine transformation

We propose a new, to our knowledge, stream cipher technique for two-dimensi onal (2-D) image data that can be implemented by iterative optical transfor mation. The stream cipher uses a pseudorandom number generator (PRNG) to ge nerate a pseudorandom bit sequence. The proposed method for the PRNG is com posed of the iterative operation of 2-D affine transformation achieved by o ptical components and by modulo-n addition of the transformed images. We ex pect efficient execution of the method by optical parallel processing. We v erify the performance of the proposed method in terms of security strength and clarify problems on optical implementation by the optical fractal synth esizer. (C) 2000 Optical Society of America. OCIS codes: 100.1160, 200.3050 , 200.4960.