Trusted micro-credentials: issuance and verification with blockchain technology

Abstract

This article proposes a methodology for issuing academic micro-credentials that remain verifiable after the issuing institution ceases to exist. Existing blockchain credentialing systems still require HTTP calls to the issuer's infrastructure during verification, which fails when the institution closes. We anchor issuer identity in did:blox on the Bloxberg consortium blockchain. Only the credential hash and the issuer's Decentralized Identifiers are stored on-chain, while the Verifiable Credential remains in the holder's wallet. Verification resolves directly from the blockchain, with no dependence on the issuer. The methodology is designed for institutions to adopt through application programming interface (API) integration with existing systems. We define three design goals: issuer-independent verification, general data protection regulation (GDPR) compliance and open standards alignment. From these we derive three architectural decisions: a consortium blockchain (Bloxberg) suited to institutional deployment, a chain-anchored DID method (did:blox) that removes HTTP dependency from verification, and a hybrid on-chain/off-chain storage model that keeps personal data in the holder's wallet. Verification is independent of the issuer. The verifier resolves the issuer's identity through did:blox on Bloxberg, without any HTTP call to the issuer's domain. GDPR compliance is achieved by keeping all personal data off-chain in the holder's wallet. The architecture complies with W3C Verifiable Credentials Data Model v2.0, making credentials portable across any compliant verifier. Revocation still depends on the issuer's ability to sign new transactions, which can fail if the institution loses its signing key. The architecture is bound to a single consortium blockchain. Consortium dissolution would require migration of the trusted issuers registry. Handling of DID deactivation is unresolved in current W3C specifications (Mazzocca et al., 2025). These limitations open three research directions: formal protocols for DID deactivation and historical key attestation, multi-signature or escrowed revocation models, and cross-chain interoperability mechanisms (Deng et al., 2025) to mitigate single-consortium risk. For educational institutions, the adoption barrier is low. The institution does not operate a blockchain node, host the credential infrastructure, or learn blockchain-specific protocols. Adoption requires only key management and an API integration with the existing Student Information System. For employers and other verifiers, credential verification is reduced from postal correspondence with registrars or third-party transcript services to a quick response (QR) code scan and a cryptographic check in seconds. No intermediary is trusted. The trust comes from the consortium-governed registry on Bloxberg and from the cryptographic properties of the credential itself. Students gain ownership of their academic credentials. The Verifiable Credential lives in the holder's wallet under their control, and survives institutional changes, mergers or closures that would otherwise invalidate the verifiability of centrally hosted credentials. Cross-border recognition becomes feasible without bilateral institutional agreements, because any W3C VC-compatible verifier can validate the credential. The architecture reduces credential fraud, since each credential is cryptographically tied to an issuer DID on a public ledger. It also lowers the institutional and verifier costs of credentialing. Issuer-independent verification (through did:blox chain resolution rather than HTTP), GDPR-compliant hybrid storage, full W3C Verifiable Credentials and DID compliance, and predictable institutional costs through the Bloxberg consortium model. Institutions integrate through an authenticated API to an existing issuance backend, without operating their own blockchain infrastructure.