Quantum image encryption based on phase-shift transform and quantum Haar wavelet packet transform

An algorithm of quantum image encryption based on a normal arbitrary superposition state (NASS) is proposed by using quantum geometric transform, phase-shift transform, and quantum Haar wavelet packet transform (QHWPT) in this paper. Firstly, to scramble an image, we design an implementation circuit of quantum image pixel exchanges along diagonal lines. Next, 2((n+1)) - 2 keys randomly distributed between 0 and 2 pi are encoded in the encryption algorithm by using phase-shift transform. The huge key space makes it difficult to attack encrypted images. Then, we store image information in low frequency using QHWPT to improve encryption effect. After that, the encryption algorithms of gray image and color image are simulated by using MATLAB, respectively. Meanwhile, evaluation indexes such as histogram, complexity and correlation of adjacent pixels are analyzed. Simulation experiments show that the proposed algorithm is valid.