  The purpose of quantum private comparison (QPC) is to solve "Tierce problem"
using quantum mechanics laws, where the "Tierce problem" is to judge whether
the secret data of two participants are equal under the condition of protecting
data privacy. Here we consider for the first time the usefulness of eight-qubit
entangled states for QPC by proposing a new protocol. The proposed protocol
only adopts necessary quantum technologies such as preparing quantum states and
quantum measurements without using any other quantum technologies (e.g. unitary
operations and entanglement swapping), thus the protocol has advantages in
quantum device consumption. The measurements adopted only include
single-particle measurements, which is easier to implement than entangled-state
measurements under the existing technical conditions. The proposed protocol
takes advantage of the entanglement characteristics of the eight-qubit
entangled state, and uses joint computation, decoy photon technology, the keys
generated by a quantum key distribution protocol to ensure data privacy. We
show that when all singleparticle measurements in the proposed protocol are
replaced by Bell measurements, the purpose of the protocol can also be
achieved. We also show that the proposed protocol can be changed into a
semi-quantum protocol with a few small changes.
