Element-Level Access Control on Encrypted SQL Tables Using CP-ABE: Optimized on Reusable Sub-Policy

This research proposes EGuardSQL, a system that allows fine-grained access control at the individual data-element level for encrypted SQL databases using CP-ABE (ciphertext-policy attribute-based encryption, a method where access rules are embedded in encrypted data). The system improves efficiency by using an optimized reusable sub-policy mechanism that reduces the computational work needed for encrypting and decrypting data while maintaining security protections against collusion attacks (where multiple unauthorized users combine their access to break security).