What is a qualified electronic seal worth as evidence?

Article 35(2) of Regulation (EU) 910/2014 gives a qualified electronic seal a presumption of the integrity of the data it is linked to and of the correctness of that data's origin; Article 35(3) makes a qualified seal issued in one Member State valid as one in all of them. In practical terms it moves the burden of proof: the other side has to show the data was altered, rather than you having to show it was not.

What is a seal, and how does it differ from a signature?

A signature belongs to a natural person; a seal belongs to a legal person. Both come in ordinary, advanced and qualified forms, and only the qualified form carries the presumption. Qualified means the certificate was issued by a qualified trust service provider on an EU trusted list and the seal was created with a qualified seal creation device — supervision, not cryptography, is what makes the difference. The maths under an advanced seal can be identical.

Article 35(1) is worth reading next to it: a seal may not be denied legal effect merely because it is electronic or because it is not qualified. Unqualified evidence is admissible. It is just evidence you have to argue for.

What does the presumption actually cover?

Two things, and it is a shorter list than most write-ups imply: that the sealed data has not changed since sealing, and that it originates from the entity named in the certificate. That is all.

• Not that the sealed statement is true. A seal over a false statement gives you a reliably attributable false statement.
• Not that the sealer was entitled to make it. Authority is a separate question, and in the agent world it is the whole question.
• Not when it happened. Time is a different instrument: a qualified electronic time stamp under Article 41 carries its own presumption of the accuracy of the date and time. If the moment matters to your case, the seal alone does not carry it.

What do you get without a seal, from a hash and a log?

Quite a lot, and it stops in a specific place. Canonicalising a record (RFC 8785) and hashing it means anyone can recompute the hash and detect a changed byte. Appending that hash to a Merkle tree (RFC 6962) and publishing the signed tree head means a record cannot be removed or reordered without breaking an inclusion proof that third parties already hold.

Where it stops: a transparency log is only as good as the guarantee that its operator never published a different tree to somebody else. Until the heads are anchored somewhere the operator does not control, “the log says so” means “the operator says so, in a form that is expensive to fake consistently”. That is genuinely better than a database row and genuinely less than a presumption in law.

Does sealing the tree head cover every receipt underneath it?

That is an open legal question, and anyone who answers it confidently is guessing. The technical construction is sound — an inclusion proof binds a specific record to a specific signed head, so a seal over the head is arithmetically a statement about every leaf under it. Whether the Article 35(2) presumption travels down that proof to an individual record is a question about how a court reads “the data to which the qualified electronic seal is linked”, and it has not been tested.

It matters commercially, not just academically: qualified seals are priced per operation, and at agent volumes a seal per record can cost more than the decision it documents is worth. Sealing heads instead of records is the design that makes the economics work, and its legal strength is the open question underneath it. We would rather write that down than have you discover it.

Where Mandaton stands today

Receipts are canonicalised, hashed, and logged, and the tree head is signed by a key held in a European key management service. They are not qualified seals. The trust service provider integration is the next milestone, and until it is live nothing on this site claims the presumption above. A vendor that oversells its own evidence has sold you the wrong thing twice.

Check a receipt yourself → · How the pipeline fits together →

Ask about the seal roadmap