(ICBC 2026) Blockchain-Based Credential Systems in Higher Education: A Comparative Review and Research Gap Analysis

Blockchain technology has emerged as a transformative infrastructure for securing, verifying, and sharing academic credentials. Over the past nine years (2017-2026), numerous blockchain-based credential systems have been proposed, spanning on-chain platforms, hybrid storage architectures, Self-Sovereign Identity frameworks, and privacy-preserving verification mechanisms. Despite this proliferation, the field remains fragmented: systems are developed in isolation, rarely comply with international standards, and do not integrate with the Learning Management Systems (LMS) in which academic activities are actually conducted. This paper presents a structured comparative review of twenty-four representative blockchain-based credential systems published between 2017 and 2026, identified through searches of major academic databases (IEEE Xplore, ACM Digital Library, Scopus, ScienceDirect, MDPI, and arXiv) and backward snowballing. Each system is analyzed using an author-defined five-criteria framework: blockchain utilization (CR1), smart contract support (CR2), W3C Verifiable Credentials compliance (CR3), LMS integration (CR4), and middleware/interoperability capability (CR5). The review classifies the systems into seven taxonomic categories across five evolutionary phases, and derives six research gaps from the comparative matrix. The key finding is that no analyzed system satisfies all five criteria simultaneously: while blockchain utilization is near-universal, W3C compliance, LMS integration, and middleware interoperability remain critically underexplored. The complete absence of university-level middleware architectures connecting LMS platforms to blockchain-based credential infrastructure via full W3C standards constitutes the most significant gap. A six-direction research agenda is proposed to guide future work.