An optical Hash function construction based on equal modulus decomposition for authentication verification

This paper proposes a Hash based authentication scheme that employs equal modulus decomposition (EMD) and fractional joint transform correlator. An 8-bit grey scale image is separated into its constituent bit plane matrices. Each bit plane matrix is subjected to EMD encryption procedure employing numerically generated random phase mask (RPM) and amplitude mask (AM). The EMD encryption results into two complex functions, which are used for the generation of phase mask and amplitude mask for the next bit plane matrix. A two round EMD procedure is carried out to obtain an 8-bit intensity matrix which is Fourier transformed and its central frequency components are extracted to obtain a 256-bit Hash value. Numerical simulations have been carried out to validate the effectiveness and performance of the proposed scheme.