Asymmetric double image encryption using computer-generated holography, QZ synthesis, and unequal modulus decomposition
Ayushi Bansal, Pankaj Rakheja, Hukum Singh
Abstract
In this paper, an innovative asymmetric double image encryption scheme is proposed that integrates computer-generated holography (CGH) with Quasi-Zernike synthesis (QZS) and unequal modulus decomposition within the gyrator transform domain. The quasi-Zernike synthesis (QZS) technique combines two input images into a single-channel cryptosystem, improving efficacy and practicality, while unequal modulus decomposition expands the overall keyspace and adds security. To strengthen the encryption, a hybrid transform incorporating fractional Fourier transform, Kekre transform, and Hadamard-Walsh transform is used in varying proportions. It offers flexibility in combining orthogonal bases, making it adaptable for multiple applications. Multiple standard images are used to validate the scheme. Statistical, key sensitivity, and attack analyses confirm the sturdiness and efficacy of the proposed system, with high metrics (CC=1,NPCR=99.61263%, and UACI=33.333%), entropy (7.9956), and execution time of 0.524535 seconds. A comparative analysis with existing techniques highlights improved statistical performance and security against numerous attacks, including brute-force, noise, special and differential attacks.