Improved multiparty quantum private comparison based on quantum homomorphic encryption

Quantum homomorphic encryption has obvious superiority in privacy protection. In this paper, we propose an improved multiparty quantum private comparison protocol based on quantum homomorphic encryption. Firstly, a trusted key center is introduced to se-curely assist the distribution of the encryption keys and update of decryption keys, while preventing a malicious server from launching an attack that announces a false result. It can significantly improve the security of the protocol while ensuring that all participants get the correct comparison results. Then, our protocol is different from the previous protocols that use the help of a semi-honest third-party. The third-party in our protocol can be almost dishonest and will faithfully perform the homomorphic evaluation on the encrypted data without decryption. Finally, by preparing single photons, multiple participants request homomorphic computations from an almost dishonest third-party in parallel and there is no need for detection of the decoy photon, which greatly reduces the consumption of quantum resources. In addition, the correctness of the protocol is verified by the IBM Q experimental platform.(c) 2022 Published by Elsevier B.V.