Best Practices
Please note that this specification is suitable for pre-production pilot implementations.
Overview
Supply chain transparency is not just a matter of issuing verifiable credentials — it requires solving a series of interconnected challenges that arise when many independent actors exchange sustainability data across complex, multi-tier value chains. This section describes common supply chain challenges and presents how UNTP can be used to address each of them. Each design pattern is non-normative best practice guidance for UNTP implementers.
Transparency Graphs
Challenge: Verifying a single credential proves it hasn't been tampered with and was issued by the stated issuer — but it says nothing about whether the graph of linked claims across many credentials is trustworthy. Real compliance verification requires following chains of evidence across multiple credentials issued by different parties: confirming issuer identity, checking accreditation of conformity assessment bodies, tracing product origins through traceability events, and verifying mass-balance consistency.
Solution: UNTP provides a method to recursively discover credentials via identity resolvers, assemble them into a linked-data transparency graph that represents your value chain, and verify the graph against tiered business rules — from core UNTP validation through industry-specific, geography-specific, and organisation-specific rules.
Different Digital Maturities
Challenge: Supply chains will operate with a mix of paper certificates, PDF documents, and digital credentials for years to come. Upstream suppliers may not yet issue verifiable data (no machine-readable structure, no cryptographic integrity, no consistent discovery). Downstream customers may not yet be equipped to consume digital credentials.
Solution: Use AI (Large Language Models) to transform unstructured upstream data into graph-compatible linked data — flagged as unverified — so that the same validation rules can run across the entire graph regardless of source maturity. For downstream consumers, every UNTP credential is designed to be both human-readable (via render templates and hosted verifier links) and machine-readable, so a single credential serves all maturity levels.
Mass Balance
Challenge: When qualifying and non-qualifying materials are mixed during production, a manufacturer could fraudulently claim the entire output as sustainable — re-using valid input credentials across a larger volume than they cover. Verifying mass-balance integrity requires visibility of all facility inputs, outputs, and production processes, but this data is almost always commercially confidential.
Solution: Record every input shipment, production run, and output shipment as verifiable traceability events with quantity data. An independent auditor verifies that output sustainability claims never exceed input quantities, issuing a conformity credential that attests to mass-balance integrity — without exposing the facility's confidential production data to buyers or competitors.
Linked Lifecycle Data
Challenge: A product's lifecycle extends far beyond the factory gate — through retail, use, repair, refurbishment, and end-of-life processing. But the original manufacturer may no longer exist when lifecycle events need to be recorded years later, and re-issuing product passports creates problems of provenance, authorisation, and fragmentation.
Solution: Maintain the original Digital Product Passport as an immutable, cryptographically signed record. Authorised parties (service centres, recyclers, owners) add lifecycle events as new linked credentials via the identity resolver — building a complete, verifiable audit trail without modifying the original passport.
Variant-Based Disclosure
Challenge: Different supply chain actors — the public, customers, regulators, auditors, recyclers — need access to different claims within the same credential. But credential-level access control is too coarse-grained: a party either has access to an entire credential or they don't.
Solution: Publish multiple document variants of the same credential, each containing a role-appropriate subset of claims with stubs indicating what other data exists. The identity resolver routes requests to the appropriate variant based on an access role parameter, enabling claim-level granularity without requiring cryptographic selective disclosure.
Digital Wallets
Challenge: The verifiable credentials ecosystem assumes a human holder presenting credentials from a wallet on demand. But UNTP credentials describe inanimate products — a box of goods, a shipment of steel — that cannot participate in presentation exchanges. The wallet-centric model does not fit supply chain transparency as the primary exchange pattern.
Solution: UNTP centres on resolver-based credential discovery rather than wallet-based presentation, ensuring any party with access to a product identifier can find credentials without prior relationships or specific software. Wallets remain a complementary mechanism for organisational authentication, regulatory compliance in wallet-mandated jurisdictions, and B2B credential exchange.
Durable Storage
Challenge: UNTP credentials must remain verifiable for the lifetime of a product — potentially decades — but issuing organisations may cease operations and stop paying for hosting. Conventional web hosting and even commercial cloud storage fail once the bills stop being paid.
Solution: Use content-addressable, economically incentivised storage protocols (IPFS/Filecoin or Arweave) where the credential's address is derived from its content hash, storage persists independent of the original publisher, and tamper-evidence is guaranteed at the storage layer. This provides post-issuer and post-provider durability without requiring centralised government registers.