Stream cipher based on pseudorandom number generation with optical affine transformation.

We propose a new, to our knowledge, stream cipher technique for two-dimensional (2-D) image data that can be implemented by iterative optical transformation. The stream cipher uses a pseudorandom number generator (PRNG) to generate a pseudorandom bit sequence. The proposed method for the PRNG is composed of the iterative operation of 2-D affine transformation achieved by optical components and by modulo-n addition of the transformed images. We expect efficient execution of the method by optical parallel processing. We verify the performance of the proposed method in terms of security strength and clarify problems on optical implementation by the optical fractal synthesizer.