Simulation of the BB84 Quantum Key Exchange Protocol

Currently, quantum cryptography is a topical and well-researched topic in the face of the emerging quantum computing platform. The BB84 quantum key exchange protocol was first proposed in 1984, and then there have been improvements to this protocol, such as the E91 and B92 protocols. The idea of this study is based on the BB84 quantum key exchange method, simulating the key exchange process in quantum to obtain a shared key, and design programming of basic quantum gates such as Hadamard, X used in the BB84 protocol. From that, determine the corresponding alphabet table for the quantum states used. As a result, calculating the key exchange between the two parties with a public key size of about 1000 bits, the computation time takes 2,3913s. When the public key size goes up to 4000 bits, it takes about 15,7111s. This shows that the execution speed of quantum key exchange according to the BB84 protocol has significantly improved and ensured safety in the quantum computer system.