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UC-029: Query Audit Trail

Reference Flow

Corresponds to Flow 7 — Traceability and Audit (Query section).

Functional Specification

This use case defines intended behavior. Audit trail querying is not yet implemented.

Description​

An authorized auditor queries the blockchain for audit records. The query returns on-chain data (hashes, timestamps, event types, participating DIDs) without exposing personal data. If the auditor needs complete detail, they must request access to off-chain storage, which requires authorization and — if containing personal data — the Holder's consent.

Actors​

  • Auditor: Authorized person or entity querying audit records
  • Blockchain: Distributed network where audit hashes and metadata are stored
  • Holder: User whose consent may be required for accessing off-chain personal data

Preconditions​

  • The auditor has authorization to query audit records
  • Audit records exist on the blockchain (UC-028)

Main Flow​

  1. The auditor queries the blockchain filtering by DID, date range, or event type
  2. The blockchain returns on-chain records: hashes, timestamps, event types, and participating DIDs — no personal data is exposed
  3. If the auditor needs complete detail, they request access to off-chain storage
  4. Off-chain access requires authorization and, if containing personal data, the Holder's explicit consent

Alternative Flows​

AF-1: No records found​

  • At step 2, no records match the query criteria
  • The auditor is informed and can adjust the search parameters

AF-2: Off-chain access denied​

  • At step 4, the auditor does not have sufficient authorization or the Holder has not consented
  • Only the on-chain records (hashes, metadata) are available

AF-3: Off-chain data deleted (right to erasure)​

  • At step 3, the off-chain detail has been deleted per GDPR right to erasure
  • The on-chain hash still exists as evidence that the operation occurred, but the detail is no longer available

Postconditions​

  • The auditor has received the requested audit records
  • On-chain records are always available (immutable)
  • Off-chain personal data access is governed by authorization and consent

Modules Involved​

ModuleRole
frontendAudit query interface, results display
backendQuery orchestration, authorization verification, off-chain data retrieval
blockchainAudit record queries (by DID, date, event type)
storageOff-chain detail retrieval (with authorization)

Technical Notes​

  • On-chain queries: Filter by DID, date range, or event type — returns only hashes, metadata, and DIDs
  • Off-chain access: Requires separate authorization — personal data access requires Holder consent per GDPR
  • Right to erasure: Off-chain personal data can be deleted per GDPR — on-chain hashes remain as they are not personal data
  • Audit independence: The on-chain record provides tamper-proof evidence independent of the platform operator
  • Standards: GDPR (right of access, right to erasure), eIDAS 2.0 (audit requirements)