Mediated authenticated differential phase shift quantum key distribution

This paper proposes the first mediated authenticated differential phase shift quantum key distribution (DPS-QKD) protocol. An untrusted third party is introduced to reduce the burden of the sender and help two participants to share a session key. Besides, a pre-shared secret key between two participants is used for mutual authentication and key distribution without assuming the existence of an ideal authenticated classical channel needed in existing DPS-QKD schemes. The security analysis shows that our modified scheme is resistant to the Trojan-horse attack, and the unconditional security proof is presented.