A Hybrid AES-256 and Permissioned Blockchain Framework with Smart-Contract-Style Access Control for Tamper-Evident Educational Record Management: Design and Performance Evaluation

Abstract: Educational institutions hold academic records whose confidentiality and integrity are essential for credential verification. This paper presents a four-layer framework combining AES-256-CBC encryption, SHA-256 hash anchoring on a permissioned ledger, off-chain ciphertext storage, and smart-contract-style role-based access control with an append-only audit log. A Python prototype was evaluated functionally on three anonymised records and quantitatively on 200 synthetic records using a university marks-sheet schema, with metrics averaged over seven runs. Mean encryption and decryption times were 0.0354 ms and 0.0227 ms per record, while mean block-append latency was 0.0068 ms. Encrypted storage increased by 37.85%, whereas the on-chain digest footprint remained 64 bytes per record. All 20 deliberately corrupted records were detected. The single-node in-memory ledger makes throughput figures computational upper bounds rather than production measurements.

Keywords: student data security; AES-256; permissioned blockchain; SHA-256 hash anchoring; role-based access control; smart contracts; tamper detection; educational records