SECURE CONSORTIUM-BASED BLOCKCHAIN CERTIFICATE ISSUANCE ARCHITECTURE COMPLIANT WITH EUROPEAN PERSONAL DATA PROTECTION REQUIREMENTS FOR E-LEARNING SYSTEMS

Abstract

The object of research is blockchain-based certification systems for educational achievements in e-learning. According to the HireRight Global Benchmark Report (2025), up to 47% of employers in the EMEA region identify education-credential discrepancies during screening, confirming the topic’s relevance. Existing blockchain solutions target a single issuer, lack a mechanism reconciling ledger immutability with the GDPR right to erasure (Art. 17), and lack an LMS integration methodology. An architectural model and prototype of a consortium CertificateRegistry system were developed, combining: separation of data into an immutable on-chain hash (SHA-256, Merkle Root) and an erasable off-chain personal-data store; role-based access control separating issuer and administrator roles, enabling one registry to serve a university consortium; and a methodology for Moodle LMS integration via Webhooks, REST API and LTI 1.3. Known solutions implement these mechanisms separately or not at all; here they are combined in one contract architecture. Deleting off-chain data turns the on-chain hash into an «orphan» that no longer identifies a person, removing the contradiction between immutability and the right to erasure. The prototype passed unit testing (15 test cases) and functional testing on Ethereum Sepolia; the calculated cost of certificate issuance on Polygon PoS is $0.00001, user testing showed fraud-detection accuracy rising from 66.7% to 100%, and portal usability (SUS) reached 82.5 of 100. The results can be applied by consortia of higher education institutions on Moodle within the EU legal framework to deploy verifiable digital certificates without significant infrastructure costs.