An Efficient Post-Quantum Collaborative Encryption Scheme for Mobile Internet Environment

The rapid development of the mobile internet has elevated data privacy protection to a critical priority. However, current encryption mechanisms for mobile devices face significant challenges. First, reliance on single cryptographic keys risks exposing the ciphertext space if an individual user’s private key is compromised. Second, the emergence of quantum computing threatens traditional algorithms, while existing post-quantum threshold schemes often impose prohibitive computational and communication overheads on resource-constrained devices. To address these issues, we propose an efficient Post-Quantum Collaborative Encryption Scheme (PQCES) tailored for mobile internet environments. PQCES designs a distributed key-splitting protocol that decentralizes key control, ensuring that independent decryption by any compromised user is cryptographically infeasible. To counter quantum threats while supporting heterogeneous mobile internet data, we instantiate our framework using both BFV and CKKS instantiations under the ring learning with errors assumption. By incorporating an aggregation server, PQCES significantly reduces user-to-user interactions, achieving a constant O(1) uplink communication overhead per user and a zero-depth homomorphic multiplicative overhead on the user side, thereby minimizing the computational and communication burden for resource-constrained mobile devices. Security analysis confirms that PQCES is able to preserve indistinguishability under chosen-plaintext attack and joint key security, providing a robust post-quantum security level of at least 128-bit. Empirical evaluations demonstrate that PQCES achieves a competitive decryption throughput of up to 1.61 × 10⁷ bits/s, delivering a significant speedup over baseline threshold schemes, verifying its efficiency and scalability for resource-constrained mobile deployments.