Bit leakage-resistant quantum private magnitude comparison

Abstract

Lots of ready quantum private comparison (QPC) protocols usually only judge whether two users’ data are equal, whereas the quantum private magnitude comparison (QPMC) protocol can compare the magnitude of two numbers, whose results are greater than, equal and less than. It is by announcing a comparison result of two bits in two data that the existent QPMC protocols determine the size relationships of the whole data. Although the announcement leaks no information to outside attackers, yet it alerts two participants to know each other’s value of a certain bit. This is termed as bit leakage in this paper. In order to remedy this shortage, the paper proposes a novel QPMC protocol using a type of Bell state. The protocol is thoroughly analyzed, correct and secure. Also, it proves free of bit leakage. Additionally, because it is easier to implement because of the usage of a type of Bell state, it counts as a better alternative for QPMC.