Lattice-Based Forward Secure Multi-User Authenticated Searchable Encryption for Cloud Storage Systems

Public key authenticated encryption with keyword search (PAEKS) has been widely studied in cloud storage systems, which allows the cloud server to search encrypted data while safeguarding against insider keyword guessing attacks (IKGAs). Most PAEKS schemes are based on the discrete logarithm (DL) hardness. However, this assumption becomes insecure when it comes to quantum attacks. To address this concern, there have been studies on post-quantum PAEKS based on lattice. But to our best knowledge, current lattice-based PAEKS exhibit limited applicability and security, such as only supporting single user scenarios, or encountering secret key leakage problem. In this paper, we propose FS-MUAEKS, the forward-secure multi-user authenticated searchable encryption, mitigating the secret key exposure problem and further supporting multi-user scenarios in a quantum setting. Additionally, we formalize the security models of FS-MUAEKS and prove its security in the random oracle model (ROM). Ultimately, the comprehensive performance evaluation indicates that our scheme is computationally efficient and surpasses other state-of-the-art PAEKS schemes. The ciphertext generation overhead of our scheme is only 0.27 times of others in the best case. The communication overhead of our FS-MUAEKS algorithm is constant at 1.75MB under different security parameter settings.