Patent attributes
Methods, apparatus, and systems are provided for performing a quantum key distribution (QKD) protocol between a first device, a second device, and an intermediary device. The intermediary device transmitting: a first secret symbol string over a first quantum channel to the first device; a first basis set over a first communication channel to the first device. The intermediary device; a second secret symbol string over a second quantum channel to the second device; a second basis set over a second communication channel to the second device. The intermediary device generating a third symbol string based on combining the first and second secret symbol strings and transmitting to the second device, via the second communication channel, data representative of the third symbol string. The first device and second device perform a quantum key exchange and sifting based on the corresponding received first and second secret symbol strings and first and second basis sets, and a fourth set of symbols generated by the second device generates a fourth set of symbols based on combining the second received secret symbols with the received third symbol string.