Graph state-based quantum authentication scheme

Inspired by the special properties of the graph state, a quantum authentication scheme is proposed in this paper, which is implemented with the utilization of the graph state. Two entities, a reliable party, Trent, as a verifier and Alice as prover are included. Trent is responsible for registering Alice in the beginning and confirming Alice in the end. The proposed scheme is simple in structure and convenient to realize in the realistic physical system due to the use of the graph state in a one-way quantum channel. In addition, the security of the scheme is extensively analyzed and accordingly can resist the general individual attack strategies.

CRYPTANALYSIS OF THE QSDC PROTOCOL WITHOUT USING PERFECT QUANTUM CHANNEL

We study the security of quantum secure direct communication without perfect quantum channel. Our analysis is focused on a general individual attack, i.e. entangle-ancilla attack. The sufficient and necessary condition for a successful eavesdropping operation is obtained, and a particular attack is presented, by which Eve can elicit the whole secret without being discovered. Finally we find the root of this loophole and give a possible improvement of this protocol accordingly.

A TWO-STEP CHANNEL-ENCRYPTING QUANTUM KEY DISTRIBUTION PROTOCOL

A two-step channel-encrypting quantum key distribution protocol is proposed. Using the previously shared EPR pairs as the quantum key, two bits of classical key can be established via one information carrier EPR state on average. In theory, the efficiency of this protocol reaches 100%, and there is no need to consume any entangled states including both the quantum key and the information carriers in ideal condition. The protocol can resist the particular attack that is fatal to other some channel-encrypting schemes. Principally, we prove the security against the most general individual attack of this protocol. Entanglement collapse in practical situation, as well as the realistic implementation of this protocol is also discussed.