Lattice-based public key encryption with equality test supporting flexible authorization in standard model
This work addresses privacy protection in encrypted data applications like health records and email filtering by providing a quantum-resistant solution, though it is incremental as it builds on prior PKEET-FA schemes.
The authors tackled the lack of quantum-safe and standard model secure public key encryption with equality test supporting flexible authorization (PKEET-FA), proposing three lattice-based constructions and implementing one over ideal lattices to achieve security against quantum attacks.
Public key encryption with equality test (PKEET) supports to check whether two ciphertexts encrypted under different public keys contain the same message or not. PKEET has many interesting applications such as keyword search on encrypted data, encrypted data partitioning for efficient encrypted data management, personal health record systems, spam filtering in encrypted email systems and so on. However, the PKEET scheme lacks an authorization mechanism for a user to control the comparison of its ciphertexts with others. In 2015, Ma et al. introduce the notion of PKEET with flexible authorization (PKEET-FA) which strengthens privacy protection. Since 2015, there are several follow-up works on PKEET-FA. But, all are secure in the random-oracle model. Moreover, all are vulnerable to quantum attacks. In this paper, we provide three constructions of quantum-safe PKEET-FA secure in the standard model. Proposed constructions are secure based on the hardness assumptions of integer lattices and ideal lattices. Finally, we implement the PKEET-FA scheme over ideal lattices.