How a seal proves a document without showing it

For centuries a letter was trusted because of a blob of wax. Nobody could read the seal’s meaning in the wax itself; what mattered was that it was whole, and that it was the right seal. Digital certificates keep the same promise with better wax. You do not need mathematics to understand them, only three ideas.

Idea one: a fingerprint of a text

Imagine a machine that reads a document and gives back a short fingerprint: a string of characters that belongs to that exact text. Change one comma and the fingerprint changes completely, not a little. The machine works in one direction only: from the fingerprint, nobody can rebuild the document.

That is useful twice. You can publish the fingerprint without publishing the document, and anyone who later holds the document can check that it is the same one.

Idea two: a book whose pages hold each other

Now imagine a bound ledger where each new page carries the fingerprint of the page before it. Tear out a page, or rewrite an old line, and every page after it stops matching. A history kept this way can grow, but it cannot be quietly changed. This is what people mean, at heart, when they speak of a chain.

Idea three: a signature only one person can make

A digital signature works like a seal that only its owner can press but that anyone can recognise. The person signing keeps something private; the world holds the matching public half and can confirm the seal is theirs. The signature also covers the fingerprint of what was signed, so the two cannot be separated and reused.

What this proves, and what it does not

It proves that a record has not changed since it was sealed, and who sealed it.

It does not prove, by itself, that a work is by the artist. That comes from people: the artist, the gallery, the papers, the history. The seal keeps their word intact over time.

It does not need to expose you. A public check can confirm the work and its seal while your name and your price stay out of sight.

On our certificates

Each change to one of our certificates is sealed against the one before, and anyone with its QR can check that the chain holds. We will not describe the machinery behind it in more detail than this, and you should be a little wary of anyone who would: the security of a seal never depended on everyone knowing how the wax was made.

If you would like company

This is what we do every day from Mexico City: help people find, buy and live with original contemporary art, with its papers in order. Book a free 30-minute call, or look at how our certificates work.