Semi-quantum private comparison based on Bell states

Abstract

In this paper, we propose two semi-quantum private comparison (SQPC) protocols based on Bell states. With the help of a semi-honest quantum third party (TP), two classical users can compare the equality of their secrets without leaking them. That TP is semi-honest means she may misbehave on her own, but she is not allowed to conspire with any user. The quantum measurement is not invoked in the first protocol, whereas the classical user in previous SQPC protocols has to be equipped with quantum measurement equipment. In the second protocol, the classical user prepares the opposite states based on her (his) measurements. By this way, all cases can produce the sharing key. The two protocols are more efficient than the previous SQPC protocols. What is more, we show that our protocols are secure against some famous attacks, such as the intercept-resend attack, the measure-resend attack, the entangle-measure attack and the participant attack.