CRYPTANALYSIS OF THE QUANTUM STATE SHARING PROTOCOL USING FOUR SETS OF W-CLASS STATES

Abstract

Recently, a protocol is proposed for the quantum state sharing (QSTS) of an arbitrary three-photon state using four sets of W-class states. Unfortunately, its security analysis is inadequate. In this paper, we find the security loophole of this QSTS protocol. It is mainly caused by the fake quantum channel, whose security is not guaranteed by the legal participants. We present a simple but feasible strategy, by which an eavesdropper can successfully steal the exact secret. Furthermore, a secure QSTS protocol is put forward. The security of our improved protocol is analyzed in details.