Verifiable ledger
Two jobs for a ledger. Everything else is a liability.
Anchoring proves a record existed in a given state at a given time. A revocation registry stops a withdrawn certification validating forever. Passport data itself stays off the ledger — because regulated product data sometimes has to be corrected.
- On the ledger
- Digests only
- Token
- None
- Wallet
- Not required
Definition
Does a Digital Product Passport need a blockchain?
No. Passport records are not stored on a ledger, because regulated product data must sometimes be corrected or erased and immutability prevents both. A ledger is used only for anchoring — proving a record existed in a given state at a given time — and for revocation registries no single party should control.
Verifiable Credentials themselves do not require one either. A W3C Verifiable Credential is a signed document; verification needs the issuer’s key, resolved via a Decentralized Identifier, and only some DID methods use a ledger at all.
Scope
What goes on the ledger, and what never does
| Data | On the ledger? | Why |
|---|---|---|
| Credential digests | Yes — a hash only | Proves prior state without publishing the content |
| Revocation status | Yes | No single party should be able to un-revoke silently |
| Passport records | No | Must be correctable; errors and mistaken submissions happen |
| Supply chain events | No | Volume and correctability both rule it out |
| Personal data | Never | The right to erasure and immutability cannot both hold |
| Commercial terms | Never | Not in the passport at all, let alone on a public ledger |
Capabilities
What anchoring buys you
Proof of prior state
Show that a record said what it said on a given date, without republishing it.
Independent timestamping
The date does not depend on our clock, our database or our continued existence.
Revocation that holds
A withdrawn certification stops verifying, checked at read time against the registry.
Digest, never content
Only a hash is published, so anchoring reveals nothing about the record itself.
Erasure stays possible
Because the record is off-ledger, a correction or an erasure request can be honoured.
No token, no wallet
Nothing for you to acquire, hold or explain to procurement. Anchoring costs are ours.
Mechanism
How an anchored claim is verified later
- 01
Issue and hash
The credential is signed by its issuer, and a cryptographic digest of it is computed.
- 02
Anchor the digest
The digest is published to the ledger. The content is not — only proof that something with that exact hash existed.
- 03
Verify the signature
A reader checks the issuer signature against their Decentralized Identifier, which resolves independently of us.
- 04
Check the anchor
Re-hashing the credential and finding that digest anchored on the stated date proves it has not changed since.
Answers
Frequently asked questions
Is a Digital Product Passport stored on a blockchain?
Not in CirculeID, and it should not be anywhere. Passport data must sometimes be corrected, and occasionally erased — a supplier name entered in error, a personal detail that should never have been submitted. An immutable ledger makes both impossible, which turns a compliance feature into a compliance problem.
So what is the ledger actually for?
Two narrow jobs. Anchoring: publishing a cryptographic digest so anyone can later prove a specific record existed in a specific state at a specific time. And revocation: a status registry that no single party controls, so a withdrawn certification cannot keep validating because the issuer failed to say otherwise.
Do Verifiable Credentials require a blockchain?
No, and this is the most common misconception in the category. A W3C Verifiable Credential is a signed document; verifying it needs the issuer’s public key, resolved through a Decentralized Identifier method. Some DID methods use a ledger, others use DNS or web hosting, and the credential model is indifferent.
Is there a token involved?
No. There is no token, no wallet requirement and nothing for a customer to hold or trade. Anchoring costs are ours and are invisible to you. A passport platform that needs its buyer to acquire a token has added a procurement obstacle in exchange for nothing the buyer asked for.
How does anchoring survive if we leave the platform?
The anchor is a public record independent of us, and the credential it attests to is a standards-based document you hold. Verification uses the digest and the issuer’s Decentralized Identifier — neither of which resolves through CirculeID — so proof of prior state outlives the contract.
Next step
Ask us where the ledger is not used
It is a better question than the reverse, and the answer tells you whether a vendor has thought about correction, erasure and the fifteen-year case.