A Systematic Review of Hybrid Encryption Techniques for Secure and Scalable Cloud-Based File Storage and Sharing Systems

Cloud-based file storage and sharing systems offer scalability, cost-efficiency and remote accessibility, but outsourcing data to third-party cloud service providers introduces significant confidentiality, integrity and access-control risks. Neither purely symmetric nor purely asymmetric cryptographic schemes satisfactorily address these risks in isolation: symmetric algorithms such as AES offer high throughput but weak key-distribution properties, while asymmetric algorithms such as RSA offer secure key exchange at substantially higher computational cost. This has motivated a large body of research into hybrid encryption techniques that combine multiple cryptographic primitives — symmetric-asymmetric combinations, attribute-based encryption (ABE), homomorphic encryption, convergent encryption for deduplication, and blockchain-integrated access control — to jointly achieve confidentiality, fine-grained access control, scalability and performance. This paper presents a systematic review of hybrid encryption techniques for secure and scalable cloud-based file storage and sharing systems, synthesizing findings from peer-reviewed surveys and primary studies retrieved through structured literature search. The review develops a taxonomy of hybrid encryption approaches, summarizes their reported security and performance characteristics, and discusses persistent open challenges including key management complexity, the quantum vulnerability of RSA-based hybrid schemes, the computational overhead of fully homomorphic encryption, the tension between data deduplication and per-user encryption, and the scalability limits of blockchain-based access control. All claims in this review are attributed to their original cited source; no performance figures are invented.