Hui-Juan Zuo

Security analysis of quantum multi-signature protocol based on teleportation

The security of the recent quantum multi-signature protocol based on teleportation is analyzed. We show that there are some security vulnerabilities in the protocol. The detailed attack strategies are described from the aspect of participant attack. We also point out that the protocol is not secure against external attack. Finally, we give some possible countermeasures to improve the protocol.

Quantum secret sharing via local operations and classical communication

We investigate the distinguishability of orthogonal multipartite entangled states in d-qudit system by restricted local operations and classical communication. According to these properties, we propose a standard (2, n)-threshold quantum secret sharing scheme (called LOCC-QSS scheme), which solves the open question in [Rahaman et al., Phys. Rev. A, 91, 022330 (2015)]. On the other hand, we find that all the existing (k, n)-threshold LOCC-QSS schemes are imperfect (or “ramp”), i.e., unauthorized groups can obtain some information about the shared secret. Furthermore, we present a (3, 4)-threshold LOCC-QSS scheme which is close to perfect.

A quantum protocol for millionaire problem with Bell states

We propose a quantum protocol for the millionaire problem with Bell states, where two distrustful parties can compare the values of their fortune with the help of a semi-dishonest third party. The efficiency of our protocol is higher than that of previous protocols for millionaire problem. In our protocol, any information about the values of their fortune will not be leaked out. The security of our protocol is also discussed.

Characterizing unextendible product bases in qutrit-ququad system.

Unextendible product bases (UPBs) play an important role in quantum information theory. However, very little is known about UPBs in Hilbert space of local dimension more than three. In this paper, we study the UPBs in qutrit-ququad system and find that there only exist six, seven and eight-state UPBs. We completely characterize the six-state and seven-state UPBs. For eight-state UPBs, seven classes of UPBs are found. As auxiliary results, we study the distinguishability of qutrit-ququad UPBs by separable measurements, and find that there exists a UPB that cannot be distinguished.

Bound on local unambiguous discrimination between multipartite quantum states

We investigate the upper bound on unambiguous discrimination by local operations and classical communication. We demonstrate that any set of linearly independent multipartite pure quantum states can be locally unambiguously discriminated if the number of states in the set is no more than

Arbitrated quantum signature scheme based on χ-type entangled states

\max \{d_{i}\}

Cryptanalysis of the Quantum Group Signature Protocols

max{di}, where the space spanned by the set can be expressed in the irreducible form