Eavesdropping on practical QKD system based on six-state protocol
基于六态协议的实际QKD系统的窃听问题研究

Based on practical implementations of quantum cryptography with the attenuated l aser pulses as the signal source rather than single photon, as well as lossy cha nnels, detection efficiency, dark count of single-photon counter, and technolog ical possibilities of a realistic eavesdropping, we discuss a combining eavesdro pping strategy of Breidbart basis and beamsplitting, and give a bound on maximum disturbance for a given mean photon number and transmission length for which a secret key can be distilled.