Proof files and verification

Every passport is signed with the operator’s key, so anyone can check it against the operator’s DID document without Odal. For a complete, portable proof, a node produces an evidence dossier: one signed file holding the passport and everything needed to check it.

What a dossier holds

• a signed manifest naming the passport, the issuer’s DID, the node and core versions, and a hash of every part;
• the passport’s full view and its public view, as signed at publication;
• the DID documents needed to check every signature in it;
• the passport’s audit trail;
• where they exist: the transfer chain, the end-of-life record, calculation receipts, the component tree and the qualified seal.

odal passport evidence <id> -o dossier.json   # generate and store a dossier

Three ways to check one

• Against the node: odal verify <dossier-id|file>. The node’s verifier checks every signature, the audit chain link by link, the transfer chain and, where present, the qualified seal.
• In a browser: odal-node.io/verify runs the same checks in the page, offline. The file is not uploaded. Its verdicts are tested against the node verifier’s own on every change to the site. It reports a qualified seal as not checked rather than guessing.
• By hand: every signature is a JSON Web Signature, checkable with any JOSE library against the keys in the included DID documents; the manifest’s hashes are taken over canonical JSON (RFC 8785).

What a dossier does not prove

A valid dossier proves the file is intact and was signed by the keys it names. It does not prove who controls those keys: compare the included DID document with the one the operator publishes on its own domain.

When the node is down

A node can mirror each published passport’s signed public view to a public object-storage bucket, with a signed time bound (validUntil) saying how long that copy is valid. A CDN or bucket website serves it while the node is unreachable.

odal snapshot verify <path|url> --key <base64-public-key>
odal snapshot verify <path|url> --did-url <url>

checks that time bound. You supply the key, or a DID document URL that is still reachable, because on a single-binary deployment the node also serves its own DID document, so that is unreachable too. This checks the snapshot’s outer proof only; the passport content inside still carries its own publish-time signature, checked separately.

Read next

• Security & cryptography: the signing model behind all of this.
• A passport’s lifecycle: the history a dossier carries.