Information leakage via side channels in freespace BB84 quantum cryptography

Abstract

While the BB84 protocol is in principle secure, real implementations suffer from imperfections. Here, we analyse a free space BB84 transmitter, operating with polarization encoded attenuated pulses. We report on measurements of all degrees of freedom of the transmitted photons in order to estimate potential side channels of the state preparation at Alice. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.