Abstract:

Quantum image encryption can greatly improve the efficiency with help of quantum entanglement and superposition characteristics, and has advantages over traditional image encryption algorithms in ensuring the security of information transmission. Aiming at the problem that quantum images could not be fully scrambled and confused only in the spatial domain or the transform domain, a scramble and confusion method combining the spatial domain and the transform domain was proposed. Firstly, the positions of image pixels were scrambled in spatial domain by quantum Baker map. Secondly, the gray information of pixels in spatial domain was changed by the rotation of quantum bits. The rotation angle was determined by the pseudo-random sequence generated by the cascade chaotic system. Then, the quantum state in the spatial domain was converted to the Fourier transform domain, and the quantum bits were rotated in the Fourier domain. Finally, the information in the transform domain was converted to the spatial domain by the inverse quantum Fourier transform to obtain the ciphertext image. Because the Baker map has a longer period, the key space of the proposed algorithm is larger. In addition, the rotation parameter generation based on the cascade chaotic system can reduce the burden of keys transmission. Numerical simulation results verify the security and effectiveness of the proposed algorithm, and the complexity is superior to the classical image encryption algorithm.

Key words: quantum image processing, image security, quantum Baker map, cascade chaotic system, image encryption