Every certificate prints an address catalog.obscuraflow.app/c/<number>/<version>. The page it opens checks, in the browser and without uploading the file, the Ed25519 signature of the certificate you drop, against the key the issuer publishes, and that the signed number and version are those of the address. It answers with one of five results: valid, invalid signature, unreadable certificate, unknown key, unsupported version.
Register status (superseded, revoked) cannot be queried online yet: the page shows it as “unknown outside the register”.
A certificate attests, signed and dated, the authenticity of a work or a print. It is an archival PDF (PDF/A-2b) carrying an embedded manifest signed with Ed25519: any change to the content or the page is detected on verification.
It describes the work (number, title, author, attribution, date, technique, series, rights), the certified object (for a print: number, edition, dimensions, process, signature, condition), the source file (name, SHA-256 digest, dimensions, colour profile), declarations signed by a named person, the provenance, exhibitions and publications, the notices, the signature (key fingerprint, key publication address, optional RFC 3161 timestamp) and a QR code to the verification address. Confidential provenance never appears in it.
Works that are validated or published, with an accepted attribution in the photographer role and not confidential, can be certified. An object has only one valid certificate at a time; an issued number is never reused. The app's register keeps every certificate, valid, superseded (re-issued) or revoked (public reason). The free tier issues up to 10 certificates (a re-issue does not count); beyond that, a license is required. Verifying is free.
