Double image encryption using gyrator wavelet transform
Isha Mehra, Naveen Kumar Nishchal · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2015
In this paper, we implement a novel optical information processing tool termed as gyrator wavelet transform for the application of double image encryption using amplitude- and phase-truncation approach. This approach enhances the key space in an asymmetric cryptosystem by adding supplementary security layers, i.e., family of mother wavelet and the gyrator transform order. Double input images bonded with random phase masks are independently gyrator transformed. Amplitude truncation of obtained spectrum generates individual and universal keys while phase truncation generates two real-valued functions. Each of the retrieved amplitude function is discrete wavelet transformed, which results into four different frequency bands. We have fused the obtained wavelet spectrum of an individual image by again gyrator transforming them following amplitude- and phase truncation. The obtained real-valued functions corresponding to each image are bonded to form the encrypted image. After using the correct universal key, individual asymmetric key, type of wavelet, and correct gyrator transform order, the original images are retrieved successfully. Numerical simulation results prove that the proposed scheme is more flexible and effective than existing wavelet fusion schemes.