Nonequal-length quantum image encryption based on bitplane chaotic mapping and the Arnold transformation

Abstract

Abstract In recent years, extensive research has been conducted on encryption algorithms based on square images. However, relatively few studies have evaluated nonsquare images. In this paper, we propose a novel encryption algorithm for nonequal length images. This algorithm incorporates bitplane chaotic mapping and Arnold transformation. To implement the algorithm effectively, we first transform the plain image into two binary sequences of equal size. Then, we introduce a new diffusion strategy to mutually diffuse these two sequences. Next, we utilize a chaotic map to control the swapping of binary elements between the two sequences. This process allows for the permutation of bits from one bitplane to any other bitplane. Finally, we employ the Arnold transform to scramble the positional information of the image, resulting in the final encrypted image. Using the parameters of nonequal Arnold transformation and the initial value of the Lorenz chaotic map as keys not only simplify the transmission of keys, but also makes the cryptosystem have infinite key space for resisting brute force attacks. Experimental results and security analysis verify that the proposed quantum image encryption algorithm can encrypt nonsquare images, and has good performance in terms of nonstatistical properties, key sensitivity, robustness and so on. Moreover, simulation experiments based on Qiskit successfully verify the correctness and feasibility of the quantum image encryption algorithm.