A dynamic semi-quantum private comparison protocol for size relations

Abstract Semi-quantum private comparison allows multiple ‘classical’ users who have restricted quantum capabilities to compare their private data with the assistance of a quantum third party. In this work, we propose a novel dynamic semi-quantum private comparison protocol using a circular transmission mode along with d -dimensional single-particle states. The protocol enables the comparison of data size relations among several ‘classical’ users, while the third party can only determine the relative sizes without accessing the users’ secret information. Security evaluations demonstrate that the designed protocol withstands typical external and internal attacks. Compared to previous works, this protocol offers several improvements: first, it supports dynamic addition or removal of users, enhancing applicability in practical scenarios; second, it eliminates the need for pre-shared keys, reducing quantum resource consumption; third, it avoids the use of high-dimensional multi-particle entangled states, thereby enhancing the feasibility of implementation. Therefore, the proposed protocol may have more practical potential compared to previous protocols.