We analyzed the security of the multiparty quantum secret sharing (MQSS) protocol recently proposed by Zhang, Li, and Man [Phys. Rev. A 71, 044301 (2005)] and found that this protocol is secure for any other eavesdropper except for the agent Bob who prepares the quantum signals as he can attack the quantum communication with a Trojan horse. That is, Bob replaces the single-photon signal with a multiphoton one and the other agent Charlie cannot find this cheating as she does not measure the photons before they run back from the boss Alice, which reveals that this MQSS protocol is not secure for Bob. Finally, we present a possible improvement of the MQSS protocol security with two single-photon measurements and four unitary operations.

https://arxiv.org/pdf/quant-ph/0506194.pdf

Improving the security of multiparty quantum secret sharing against Trojan horse attack

Multi-step quantum secure direct communication using multi-particle Green–Horne–Zeilinger state

We propose a theoretical scheme for secure quantum key distribution network following the ideas in quantum dense coding. In this scheme, the server of the network provides the service for preparing and measuring the Bell states, and the users encode the states with local unitary operations. For preventing the server from eavesdropping, we design a decoy when the particle is transmitted between the users. The scheme has high capacity as one particle carries two bits of information and its efficiency for qubits approaches 100%. Moreover, it is unnecessary for the users to store the quantum states, which makes this scheme more convenient in applications than others.

https://iopscience.iop.org/article/10.1088/0256-307X/22/5/006/pdf

Secure Quantum Key Distribution Network with Bell States and Local Unitary Operations

Based on EPR pairs, this paper proposes a different quantum private comparison (QPC) protocol enabling two parties to compare the equality of their information without revealing the information content. Due to the use of quantum entanglement of Bell state as well as one-way quantum transmission, the new protocol provides easier implementation as well as better qubit efficiency (near 50%) than the other QPCs. It is secure against Trojan horse attack and other well-known attacks.

New quantum private comparison protocol using EPR pairs

We present a scheme for symmetric multiparty quantum state sharing of an arbitrary m-qubit state with m Greenberger–Horne–Zeilinger states following some ideas from the controlled teleportation (2005 Phys Rev A 72 02338) The sender Alice performs m Bell-state measurements on her 2m particles and the controllers need only take some single-photon product measurements on their photons independently, not multipartite entanglement measurements, which makes this scheme more convenient than the latter Also it does not require the parties to perform a controlled-NOT gate on the photons for reconstructing the unknown m-qubit state and it is an optimal one as its efficiency for qubits approaches 100% in principle

http://iopscience.iop.org/article/10.1088/0953-4075/39/8/015/pdf

Efficient symmetric multiparty quantum state sharing of an arbitrary m-qubit state

Based on a quantum secure direct communication (QSDC) protocol [Phys. Rev. A 69 052319 (2004)], we propose a (n,n)-threshold scheme of multiparty quantum secret sharing of classical messages (QSSCM) using only single photons. We take advantage of this multiparty QSSCM scheme to establish a scheme of multiparty secret sharing of quantum information (SSQI), in which only all quantum information receivers collaborate can the original qubit be reconstructed. A general idea is also proposed for constructing multiparty SSQI schemes from any QSSCM scheme.

Multiparty quantum secret sharing

In this paper, only Bell states are employed and needed to be identified to realize the multiparty secret sharing of quantum information, where the secret is an arbitrary unknown quantum state in a qubit. In our multiparty quantum information secret sharing (QISS) scheme, no subset of all the quantum information receivers is sufficient to reconstruct the unknown state in a qubit but the entire is. The present multiparty QISS scheme is more feasible with present-clay technique.

Multiparty secret sharing of quantum information using and identifying Bell states

Improving Wojcik's eavesdropping attack on the ping-pong protocol

Many-agent controlled teleportation of multi-qubit quantum information

In this paper, by introducing the additional classical information and taking advantage of the property of quantum entanglement swapping of two photon pairs instead of the property of quantum entanglement of a photon pair, the Bostrom-Felbinger protocol [Phys. Rev. Lett. 89, 187902 (2002)] is improved. In the improved protocol, when the photon travels from the message receiver's site to the message sender's site, any attack can be detected in the control mode. Moreover, it is deterministically successful to transmit the secret messages in the message mode. The security of the present improved protocol against the eavesdropping is ensured by the Bostrom-Felbinger protocol, and besides, the attacks proposed by Cai [Phys. Rev. Lett. 90, 109801 (2003)] to attack the Bostrom-Felbinger protocol without eavesdropping can be prevented.

Zhong-xiao Man

Papers

Multiparty quantum secret sharing

Multiparty secret sharing of quantum information using and identifying Bell states

Improving Wojcik's eavesdropping attack on the ping-pong protocol

Many-agent controlled teleportation of multi-qubit quantum information

The improved Bostrom-Felbinger protocol against attacks without eavesdropping