Eavesdropping in semiquantum key distribution protocol
Boyer et al. introduced the semiquantum key distribution protocol with classical Bob and showed its robustness. However, any analysis relating the amount of information leakage to the eavesdropper and the disturbance caused by her was open. We analyze this scheme and explicitly derive eavesdropper?s advantage as a function of the disturbance. Our proposed eavesdropping strategy exploits both the directions of communication between the two parties. Our two-way eavesdropping extracts more information on the secret bits than one-way application of the strategy that worked on BB84.
semiquantum key distribution bb84 protocol binary symmetric channel cryptography optimal eavesdropping quantum cryptography