Paper 2022/199 Original: eprint.iacr.org/2022/199 ↗

Lattice-based Public Key Encryption with Multi-Ciphertexts Equality Test in Cloud Computing

Abstract

Nowadays, together with stormy technology advancement, billions of interconnected devices are constantly collecting data around us. In that fashion, privacy protection has become a major concern. The data must be in encrypted form before being stored on the cloud servers. As a result, the cloud servers are unable to perform calculations on en- crypted data, such as searching and matching keywords. In the PKE- MET setting, a cloud server can perform an equality test on a number of ciphertexts which encrypted with the same designated number. In this paper, we propose, for the first time, an efficient construction of a quantum-safe PKE-MET system based on the hardness of the Learning with Errors (LWE) problem in the lattice setting. Furthermore, we also discuss the first lattice-base public key encryption with flexible multi- ciphertext equality test (PKE-FMET) constructions, which allow per- forming equality test on multiple ciphertexts whose designated numbers are less than a threshold number. Our proposed schemes are proven to be secure in the standard model.