Private Comparison Protocol for Multiple Semi-Quantum Users Based on Bell States

Quantum private comparison has attracted the attention of many researchers in recent years, and it extends to two branches: semi-quantum private comparison and multi-party quantum private comparison, but there are not many studies on the combination of the two. Therefore, this paper proposes a multi-party semi-quantum private comparison protocol based on Bell states. This protocol uses the semi-honest third-party TP to judge the equality of private secret messages of classical users without divulging the real value. Among them, TP's quantum ability is complete, but users are limited. Our protocol differs from other similar protocol s in two points: 1. The combination of "multi-party" and "semi-quantum". 2. It can not only compare whether the secret messages of all users are equal, but also determine whether the secret messages of any two users are equal under the condition of allowing a large number of computations. Security analysis and efficiency analysis show that the protocol can resist both internal and external attacks, and it has ideal qubit efficiency.