Quantum Watermarking Algorithms Based On Maximum Pixel Difference Blocking And Quantum Haar Wavelet Transform

The ability of quantum computing to quickly process data poses a threat to classical cryptography.With the rapid development of quantum secure communication in theoretical foundations and physical experiments,scholars have begun to pay attention to and study different directions.Quantum information hiding is one of the new research directions.Two quantum watermarking algorithms and their quantum circuits based on chaotic map are designed in this dissertation.The main research work is as follows.In the quantum wavelet transform,the pixels of the image may be signed decimal fractions instead of integers.Consequently,a generalized representation of signed decimal fraction is proposed to carry the pixels in the quantum image.Based on the generalized representation of signed decimal fraction,the quantum modules including addition,subtraction,multiplication,and division operations are designed,and the quantum Haar wavelet transform is implemented.A quantum scrambling mechanism based on the Henon map is proposed to scramble the watermark image,and the scrambling effect is good.Finally,with the assistance of multiple quantum Haar wavelet transforms,a quantum watermarking algorithm based on quantum Haar wavelet transform and Henon map is presented.The complexity of the embedding process is O(7)n ~2(8),while that of the extraction process is O(7)n ~3(8).Simulation experiments show that the proposed quantum watermarking algorithm has good performance in terms of embedding ability and invisibility.A new quantum watermarking algorithm is designed by implementing the least significant bit replacement strategy based on the maximum pixel difference block method and the tent map.A quantum cover image with the novel enhanced quantum image representation is divided into non-overlapping blocks.And the difference between the maximal and the minimal pixel values in a block is calculated and compared with the predefined threshold.Then the current block is defined as an edge block or a smooth block according to the comparison result.Subsequently,an edge block could be embedded into more secret information than a smooth block due to the visual characteristic of human eyes.To enhance the security of the quantum watermark algorithm,the chaos matrix obtained by tent map is utilized in the scrambling and embedding processes.The scrambled quantum watermark image is embedded into a quantum carrier image with the least significant bit substitution strategy.The complexity of the embedding process is O(7)n ~2(8).Compared with other quantum watermark schemes,the proposed quantum watermark algorithm based on maximum pixel difference and tent map could achieve a better visual quality and a higher embedding capacity.