Quantum image encryption based on Lorenz hyper-chaotic system

According to the higher security of higher-dimensional chaotic system, a new scheme of quantum image encryption and decryption based on Lorenz hyper-chaotic system is proposed. The encryption process is mainly divided into two parts: the location information scrambling process and the color information replacement process. In the location information scrambling process, the pseudo-random sequence obtained by the Lorenz hyper-chaotic system is first sorted to obtain the corresponding position index sequence, and then the rows and columns of the position information are scrambled by the index sequence. In the process of color replacement, the change of pixel value is firstly diffused to each pixel through chaotic sequence, and then the information of each pixel is confused, so as to realize the process of color information replacement. Experimental analysis shows that the encryption scheme in this paper has a good effect.

Quantum image scrambling algorithm based on discrete Baker map

Quantum image processing has become a significant aspect within the field of quantum information processing because the image is an essential carrier of information, and quantum computation has powerful image processing ability. Image scrambling algorithms are often required as initial image operations in quantum image processing applications such as quantum image encryption and watermarking. However, the efficiency of existing quantum image scrambling algorithms needs to be improved urgently, especially in terms of periodicity. Therefore, a novel quantum image scrambling algorithm based on discrete Baker map is proposed in this paper, which can be implemented by swapping qubits with low circuit complexity. The quantum version of discrete Baker map is deduced and the corresponding quantum circuit is designed. The simulation results show that the scrambling algorithm has the characteristic of long period, which can further enhance the security of quantum image encryption algorithms. Besides, for generalized discrete Baker maps, the conditions that they can be implemented by swapping qubits are given. Moreover, the number of discrete Baker maps satisfying the conditions is also calculated.

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, [Formula: see text] keys randomly distributed between 0 and [Formula: see text] 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.