OMAHE: An Adaptive Post-Quantum Hybrid Encryption Framework with Formal IND-CCA2 Security for Cloud Object

Abstract

Cloud storage systems face escalating security threats requiring cryptographic mechanisms that jointly optimise confidentiality, performance, and quantum resilience. Single-algorithm encryption schemes are inadequate against quantum-capable adversaries and contemporary latency constraints. This paper proposes the Optimised Multi-Algorithm Hybrid Encryption Framework (OMAHE), which integrates AES-256-GCM for bulk data encryption, ECDH with Curve25519 for ephemeral key exchange, and CRYSTALS-Kyber (NIST FIPS 203) for post-quantum key encapsulation. An adaptive algorithm-selection module employs eBPF-based runtime profiling heuristics to dynamically route encryption tasks according to file size, access frequency, and security-level policy.Evaluated on a 24-node private OpenStack cluster against three baselines (AES-256-GCM pre-shared key, RSA-2048/AES, and ChaCha20-Poly1305/ECDH), OMAHE achieved 2.14 GB/s throughput for large files — a 37.8% improvement over the RSA-2048/AES baseline — while reducing key establishment latency by 52.1%, CPU utilisation by 28.4%, and energy consumption by 36.4%. These improvements carry practical significance for cloud operators seeking to migrate to post-quantum cryptography without incurring prohibitive performance penalties; however, results are specific to the hardware configuration evaluated, and generalisation to heterogeneous deployments warrants further study. Formal IND-CCA2 security is established under the MLWE hardness assumption, with forward secrecy and mutual authentication properties verified via ProVerif version 2.05.