Optical Asymmetric Cryptosystem centered on Fractional Fourier Domain using Hilbert Phase Mask

In order to enhance the con entiality we propose a new technique in visual image encryption system In this technique asymmetric cryptosystem is carried out in the Fractional Fourier Transform (FrFT). The phase masks used here are different from the random phase masks (RPM) used in conventional Double Random Phase Encoding (DRPE) system. Here, we make use of Radial Hilbert Mask (RHM) along with RPM. Also, different keys are used for encryption and decryption purpose to make the system much more secure. Mean Square Errors (M,SE) and Peak Signal to Noise Ratio (PSNR) are calculated for the proposed algorithm.