A modified protocol of quantum state sharing based on entanglement swapping and random EPR selection

Quantum secret sharing (QSS), an important branch of quantum communication, is the generalization of classical secret sharing into quantum scenario. The secret messages are split into several parts, and each part is distributed to a separate party so that no action of a subset of all the parties without the cooperation of the entire group is able to read out the secret messages. In this paper, a quantum state sharing protocol is proposed by using entanglement swapping and random EPR selection. The EPR pairs of Bell-state measurement are selected randomly by the sender Alice, which can improve the security of the scheme and raise probability of detecting Eve to 95.8%. In addition, difference coding is used in this protocol to achieve a high efficiency. The security of the present multiparty QSS against eavesdropping has been analyzed. It is convenient in application as it require only two qubit entanglements, one measuring-basis and two-qubit joint measurements, not GHZ states, for sharing an arbitrary secret two-qubit state.