Pairing-Free Certificate-Based Proxy Re-Encryption Plus Scheme for Secure Cloud Data Sharing

The popularity of secure cloud data sharing is on the rise, but it also comes with significant concerns about privacy violations and data tampering. While existing Proxy Re-Encryption (PRE) schemes effectively protect data in the cloud, challenges persist with certificate administration and key escrow. Moreover, the increasing number of users and prevalence of lightweight devices demand functional and cost-effective solutions. To address these issues, this paper presents a novel Pairing-free Certificate-Based Proxy Re-Encryption Plus scheme that leverages elliptic curve groups for improved effectiveness and performance. This scheme successfully resolves challenges related to certificate management and key escrow in traditional PRE schemes, while also introducing non-transferable and message-level fine-grained control characteristics. These enhancements bolster data security during sharing and minimize the risk of malicious information leakage. Our proposed scheme's correctness, security, and effectiveness are rigorously verified and analyzed. The results demonstrate that the scheme achieves the chosen ciphertext security in the random oracle model. Compared to current PRE schemes, our approach offers greater advantages, lower computational overhead, and enhanced suitability for practical cloud computing applications.