Classical Simulation Of Quantum Cryptography Comunication

Quantum cryptography and computer cryptography are two branches of cryptography at the same age. Quantum cryptography based on the quantum mechanics can achieve unconditionally secure communications. Since BB84 protocol was proposed, quantum cryptography attract much attention. In recent years, with the development of technology, quantum cryptography has begun to attract commecial attention. The international community has set up several quantum information processing companies.Quantum cryptography communication is a rapidly growing field, it involves many subjects, such as quantum mechanics, quantum optics, information theory, cryptography and communication technology. Currently, quantum cryptography communication is mainly used in quantum key distribution. There are a number of systems and products about quantum key distribution.In the actual quantum cryptography communication, there are many non-ideal factors (such as non-ideal single-photon source, channel noise and dark count of single-photon detector, etc.) as well as the limitations of experimental condition, the simulation with classical computers is becoming an important method of quantum cryptography communication.In this paper, classical simulation of quantum cryptography communicationis studied. The main contents of this paper are,1. Classical simulation of quantum cryptography communication based on BB84 protocol with Matlab in classical computer has been achieved. Two important quantum noisy channels for quantum key distribution are simulated. The bit rate of key after distribution is calculated.2. Since quantum capacity is equal to private classical capacity when channel is degradable. The private classical channel capacity was deprived for the phase damping channel.3. In this paper, a model to deal with the quantum bit error rate caused by dark counts was constructed. The analytical relationship of bit error and dark count was given which may find applications in reducing bit error and improving the safety distance.4. The bifurcation protocol of privacy amplification have been improved the error-correcting capacity greatly.We have improved the binary protocol, which improved the error-correcting capability greatly.