Image Encryption And Decryption Using Phase Mask over Sinusoidal Single and Cross Grating

In the journey towards secured communication, the present paper proposes a technique that can be applied to images, for its successful encryption and decryption. The key idea behind this is the sinusoidal phase grating (SPG) in optical domain. The idea is incorporated in digital domain using a set of random phase mask (RPM) and a sinusoidal phase grating (SPG) in the Fourier plane using the concept of double random phase encoding system (DRPE). As a result of larger key size, the encryption system become more secure and resistant to impulse attack, and claims to improve the level of security and confidentiality as compare to single RPM, in transmission of the image based data as well as in storage. Encryption key is formed by combining phase key functions with grating parameters. The robustness of the technique has been analysed by calculating correlation coefficient and mean-square-error (MSE) between the decrypted and the original image.