Wenping Ma

Two-party quantum key agreement with four-qubit cluster states

Based on four-qubit cluster states, we present a two-party quantum key agreement (QKA) scheme using unitary operations. In this scheme, two participants perform the unitary operation on the different photon of the same cluster state, which guarantees that each party contributes equally to the agreement key. By measuring each cluster state and decoding, these two participants can generate a four-bit classical key without the exchange of classical bits between them. Compared with other existed two-party QKA protocols, our scheme is efficient. Security analysis shows that our protocol is secure against both participant and outsider attack.

Quantum key agreement protocols with four-qubit cluster states

Based on unitary operations and four-qubit cluster states, a two-party and a three-party quantum key agreement protocols are proposed, respectively, in this paper. The two-party protocol allows that each participant contributes equally to the agreement key by one party performing the unitary operations on two photons of a cluster state and another party performing the delayed measurement on the transformed cluster state. In the three-party scheme, each party can extract the other two parties’ secret keys, respectively, encoded in the different photons of the same cluster state by performing the measurement with cluster basis and fairly generates the shared key. The security analysis shows that the two protocols can resist against both participant and outsider attacks. Furthermore, the two protocols also achieve high qubit efficiency.

Efficient bidirectional quantum secure communication with two-photon entanglement

An efficient bidirectional quantum secure communication protocol is proposed with two-photon entanglement. Compared with the previous protocol proposed by Shi et al., our protocol can achieve higher efficiency. Meanwhile, for the same length secret messages, only half of entangled photon pairs need to be prepared in our protocol. And the number of classical bits in public classical communication is also a half of that in the previous protocol. Moreover, the information leakage does not exist in our scheme.

QUANTUM PROXY GROUP SIGNATURE SCHEME WITH χ-TYPE ENTANGLED STATES

A quantum proxy group signature scheme is proposed with χ-type entangled states. Our scheme combines the properties of group signature and proxy signature. Moreover, the particles in the χ-type state sequence are used to distribute proxy warrants and quantum keys in the initial phase, and then used for quantum signature. Therefore it increases the utilization rate of quantum resources compared with the general quantum signature scheme. Finally, the unconditional security of our scheme is also analyzed.

Two-party quantum key agreement against collective noise

In this paper, two two-party quantum key agreement protocols are proposed with logical

A quantum proxy group signature scheme based on an entangled five-qubit state

\chi

A new controlled quantum secure direct communication protocol based on a four-qubit cluster state

χ-states and logical Bell states. These two protocols can be immune to the collective-dephasing noise and the collective-rotation noise, respectively. They make full use of the measurement correlation property of multi-particle entangled states and the delayed measurement technique. This ensures that two participants can exchange the secret keys of each other and fairly establishes a shared key. There is no information leakage problem when establishing a shared key. The use of the delayed measurement technique and the decoy state technology makes the two protocols resist against both participant and outsider attacks. Furthermore, the two protocols are congenitally free from the Trojan horse attacks and have high qubit efficiency.

Improvement of a controlled quantum secure direct communication protocol

Based on logical quantum states, two three-party quantum secure direct communication protocols are proposed, which can realize the exchange of the secret messages between three parties with the help of the measurement correlation property of six-particle entangled states. These two protocols can be immune to the collective-dephasing noise and the collective-rotation noise, respectively; neither of them has information leakage problem. The one-way transmission mode ensures that they can congenitally resist against the Trojan horse attacks and the teleportation attack. Furthermore, these two protocols are secure against other active attacks because of the use of the decoy state technology.