Verifiable Credentials in Supply Chains: A Primer

The trust problem credentials solve

Conventional supply chain systems record what suppliers told you. That record is only as trustworthy as the system holding it, and to a downstream party — a customer, an auditor, a regulator — it is an assertion by you about what someone else said. There is no way for them to check it independently, and increasingly that is exactly what they are being asked to do.

Verifiable Credentials change where the trust sits. The party making a claim signs it cryptographically: a testing laboratory signs a test result, a certification body signs a certificate, a supplier signs a declaration of material composition. Anyone holding that credential can verify the signature offline, against the issuer's published key, without asking you or trusting your database.

The practical consequence is that evidence outlives the system that stored it. A credential remains verifiable after you change platforms, after the supplier changes systems, and after the original database has been decommissioned, which is a meaningfully different property from a row in a table.

How the pieces fit together

Three components matter. An issuer is the party making the claim, identified by a decentralised identifier — an identifier that resolves to public keys without depending on any single registry. A credential is the signed claim itself, expressed in a standard structure so that any conforming verifier can read it. A presentation is what a holder shows to a verifier, which may contain several credentials and is itself signed.

The separation between holder and issuer is the part that is easy to miss and important in practice. A supplier holds credentials issued to them by testing labs and certification bodies, and presents them to you. You are not asking the lab anything; you are checking a signature the lab produced, which means the lab does not need to be online, integrated with you, or even still in business.

Key management is the unglamorous part that determines whether any of this works in five years. Keys rotate, staff leave, and organisations restructure. A credential scheme without a documented key rotation and revocation story produces evidence that becomes unverifiable at exactly the point somebody wants to check it.

Selective disclosure, and why it is usually the requirement

Suppliers are frequently unwilling to expose their own supply chains, because their supplier relationships are commercially valuable and disclosing them invites disintermediation. This is not obstruction; it is a rational position, and any traceability scheme that ignores it will simply not be adopted.

Selective disclosure resolves the tension. It lets a holder prove a specific property from a credential without revealing the whole credential — that a material meets a threshold without revealing the exact value, or that a component came from a certified source without naming the source. The cryptographic mechanisms differ in maturity, but the design requirement is consistent and should be established at the start.

This is the single most common reason schemes fail in adoption rather than in engineering. A design that requires full disclosure works technically and stalls commercially, and retrofitting selective disclosure afterwards usually means changing the credential structure, which means reissuing everything already in circulation.

Design decisions to settle early

• Which claims genuinely need to be verifiable by third parties, and which are internal records
• Who issues each credential type, since the issuer must be the party actually making the claim
• Which identifier method you use, and whether partners can resolve it without bespoke tooling
• Key rotation and revocation, documented before the first credential is issued
• Whether selective disclosure is required, which constrains the credential structure
• How credentials are stored and presented, and by whom, across organisational boundaries
• What happens when an issuer ceases to exist, which is a certainty over a long enough horizon

When a shared database is the better answer

Credentials are not always the right tool and it is worth being clear about when they are not. If all participants already trust a single operator, and that operator is stable, a shared database is simpler, faster and cheaper. The verification machinery is overhead that buys nothing when nobody disputes the record.

Credentials earn their cost when the verifier does not trust the holder, when the evidence must outlive the storing system, or when claims cross organisational boundaries where no shared operator exists. Regulatory contexts frequently satisfy all three, which is why the approach has gained ground in compliance-driven traceability specifically rather than in supply chain software generally.

The related question — whether a distributed ledger is needed — usually answers itself once credentials are in place. Signed credentials plus standard APIs provide tamper-evidence and independent verification without a ledger's operational cost. A ledger addresses shared mutable state that no participant can be trusted to host, which is a narrower problem than the marketing suggests.

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