An entropy increasing circuit for quantum walking and its application in quantum encryption

The rapid development of quantum computing poses a serious threat to traditional encryption technologies, especially in the field of image security, where existing encryption schemes struggle to withstand quantum attacks. Therefore, quantum image encryption research is crucial. In the field of quantum image encryption, keys with high randomness and high security are essential. To address the issue of insufficient randomness in quantum walks in low-dimensional spaces, this paper proposes two solutions: the high-dimensional quantum walk paradigm and the entropy-increasing circuit. The high-dimensional quantum walk paradigm enhances the complexity of random sequences by expanding the dimensions of quantum walks, while the entropy-increasing circuit boosts the entropy of the key through quantum operations, thereby improving its randomness and resistance to attacks. To verify the random performance of the entropy-increased key, it is applied to quantum image encryption, with the specific circuit implementation of the encryption process provided. Finally, experimental analysis demonstrates the security of the algorithm.