Authors:
Adina Rakesh Reddy, K. Jayasurya, Papisetty Pavan Kalyan

Addresses:
Department of Computer Science and Engineering, SRM Institute of Science and Technology, Ramapuram, Chennai, Tamil Nadu, India.

Abstract:

The rapid adoption of e-learning has raised concerns about online exam security, transparency, and scalability.  We introduce DeCentralEx, a decentralized hybrid system that verifies blockchain-based smart contracts and stores them in encrypted cloud storage for secure and rapid scrutiny.  It reduces on-chain data dependencies by using Ethereum smart contracts for decentralized role validation and Firebase Firestore for AES-encrypted questions and answers. Thus, DeCentralEx addresses the drawbacks of blockchain models, which have high gas fees, latency, and low concurrency. Its deployment and testing on the Sepolia testnet show good tamper resistance, secure data handling, and automatic result processing. Compared to entirely blockchain-based systems, its hybrid architecture, with a calibrated design, offers great scalability and prevents disruptions during periods of high demand.  Comparative performance testing reveals that DeCentralEx strikes a balance between security, affordability, and scalability.  Such testing confirmed its capacity to handle high concurrency with low gas usage compared to on-chain solutions.  The study's aims were confirmed, proving an implementable and pragmatic approach for online exam security. Zero-knowledge proofs and Layer 2 blockchain technology could boost efficiency and decentralization. Decentralized architecture has the potential to transform digital testing environments in academic institutions worldwide.

Keywords: Blockchain-based Examination; Smart Contracts; Online Assessment Security; AES Encryption; Cloud Storage; Hybrid Architecture; Ethereum Sepolia; Decentralized Authentication; Scalable Exam System.

Received on: 03/07/2024, Revised on: 29/09/2024, Accepted on: 28/10/2024, Published on: 03/03/2025

DOI: 10.69888/FTSCS.2025.000375

FMDB Transactions on Sustainable Computing Systems, 2025 Vol. 3 No. 1, Pages: 1-17

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