Quantum block image encryption based on Arnold transform and improved zigzag transform

With the rapid development of science and technology, image security has become increasingly critical. In this paper, a novel quantum block image encryption algorithm based on quantum Arnold transform and improved Zigzag transform is proposed. First, the classical plaintext image is transformed into quantum form with the novel enhanced quantum representation model. Then, the Quantum Arnold Transform (QArT) is utilized to scramble the image sub-blocks by manipulating the qubits that represent positional information. By iterating the block-level permutation procedure with varying block sizes and QArT parameters each time, the lack of periodicity of the QArT can be compensated to a certain extent. The scrambled image undergoes secondary diffusion through an improved Zigzag transform, altering both pixel position and pixel value. The corresponding quantum circuits are given, and the numerical simulation results demonstrate that the proposed quantum image encryption scheme is both valid and reliable for quantum image protection in terms of security and computational complexity.