A record is sealed in your browser with a real signature. Then you alter it, and the verification tells you exactly which part broke and why.
What is real here, and what is not. The keypair, the content hash, the signature and every verification are computed by your own browser using Web Crypto — Ed25519, the same algorithm the production system uses. When a check fails below, it fails because the mathematics says so.
The timestamp is illustrative only. A browser cannot reach an outside timestamp authority from this page — the site's content policy forbids it, and so it should. The attestation block is built locally to show its shape and the difference between the two grades. It is not evidence of anything. Faking a timestamp in a demonstration about timestamps would be the exact thing this architecture exists to detect.
The attestation is folded in before signing, which is the whole design: because it sits inside what was signed, a receipt cannot afterwards be re-stamped, back-dated or stripped of its timestamp without breaking the signature. The buttons below let you try.
Nothing to break yet — press Seal this record above, and five ways to attack it appear here.
Each button alters the sealed record the way somebody would if they wanted a different story told later. Nothing is re-signed — that is the point.
The form above is no longer connected to this record. Editing it now changes nothing — the verifier checks the sealed record, not the box you typed in. That is the correct behaviour and it is worth noticing: once sealed, a record is a thing in its own right. Press Seal this record again to start over with new text.
The sealed record will be printed here in full, exactly as a holder would have it.
This is what a holder would have. Everything needed to check it is in here except the private key, which never leaves the browser and is discarded when you close the page.
This page is a demonstration, not the product. The records under /records/ were produced by the real system and can be checked with a tool that runs on your machine and contacts nobody.