Overview of Optical Image Authentication Schemes; Double Random Phase Encoding and Photon Counting Imaging

Double-random-phase encoding technique (DRPE) is an optical image encryption technique which has the advantage of parallelisms with optical processing. In this study, we aim to evaluate cryptographic properties of DRPE scheme. DRPE encodes an input image into a complex-amplitude image which real and imaginary parts resemble independent stationary white noises. The encryption process can be employed by using two random phase masks as keys and two lenses in Fourier space. The original image can be decoded only when the exact keys are given. To verify the performance of the authentication of DRPE images the peak-to-correlation energy (PCE) between the reference images and the input images are computed. Further, to improve the robustness against different attacks, photon counting imaging (PCI) technique and DRPE can be integrated. PCI encrypts amplitude part of DRPE by using various numbers of photons. Experimental results demonstrate that the DRPE is highly key sensitive while the authentication verification is completely preserved. Also, results of PC-DRPE encryption technique seem to perform reasonably well in terms of security and authentication factors.