Enhancing Quantum Information Encryption System Security: An Optimization Approach with BFGS-Supported VQE Solver

With the rapid development in the field of quantum computing, the security of traditional encryption algorithms is facing serious challenges. And quantum key distribution (QKD) provides a new way to solve the key distribution problem, and QKD protocol has become a new hotspot of encryption technology. This research makes a breakthrough in optimizing and applying the unstructured QKD security proof model, which is not only applicable to a variety of QKD protocols, but also dramatically reduces the dependence on mathematical skills for solving the security key. By replacing the original classical optimization solver with a VQE optimization solver based on the BFGS algorithm, this research successfully improves the processing efficiency, simplifies the pairwise constraints, and optimizes the key rate optimization solving algorithm. In practical applications, it successfully implements the secure key rate computation and solving for the QKD protocol BB84 without security vulnerability, the measurement device independent QKD protocol, and the QKD protocol BB84 under laser seed attack. Through these application cases, this project not only verifies the wide applicability of the model, but also significantly improves the computation speed and the accuracy of key rate estimation by improving the key components in the model.