T4 Trust issues Visible Digital Seals on the international standard that lets anyone verify a document offline, in seconds, on paper or screen.
Verification chain
Valid01Acquire VDS data from the carrier, Passed
02Retrieve and validate the trust list chain, Passed
03Locate Manifest and certificate, Passed
04Validate resource signatures, Passed
05Process the Payload, Passed
06Verify the VDS signature, Passed
07Present the result (RFF), Passed
A VDS is a 2D code holding a document's key data, electronically signed by its issuer and defined by ISO 22376 and ISO 22385. No database lookup, no network needed at the moment of checking.
The document's key fields travel inside the code, signed with the Issuer's private key. Change one byte and the signature fails.
An XML rulebook per use case says which fields exist, how they are validated and how a verifier presents them.
Signed trust lists tell any verifier whether the Issuer is legitimate, all the way back to the VDSIC Root LoTL.
From civil status in Côte d'Ivoire to professional identity in France.
Côte d'Ivoire, civil status & identity
National-scale seals on civil status documents
France, professional identity
Expert-ID digital professional card
France, certification
Label attestations protected against forgery
Figures from the VDSIC case studies on vdsic.org.
How it is built, who stands behind it, which standards define it and where it goes next.