# An attestation or a register anyone can check, no account needed

> Drop a sign-off attestation or a closing register: Kolinea tells you whether it issued it, without the slightest change since.

## A PDF can be edited in two minutes

An approval attestation travels: sent to a partner, attached to a letter, brought out a year later when a dispute starts. Whoever receives it has no way of knowing whether the date, the name or the subject were touched up on the way. The document tells the truth, or it was arranged, and nothing settles which.

## The document says where to check it

Two Kolinea documents carry a reference and the address where they can be checked: the [attestation of a sign-off](/en/features/sign-off) and a folder's [closing register](/en/features/closing-and-archiving).

- **No account**: the "Verify a document" page is open to anyone. Whoever received the file drops it there, without signing up and without knowing the workspace that issued it.
- **What it answers**: "Authentic attestation" or "Authentic register", with the folder, the workspace and the date the document was drawn up, when the file is the original copy, byte for byte.
- **An altered copy**: when the file no longer matches, Kolinea finds it by the reference it carries and answers "Altered document": it says which document it comes from and when that one was drawn up, never naming the folder. A reference can also be typed in by hand, the one printed at the foot of an attestation or at the top of a register.
- **The answers in an attestation**: each answer to a sign-off is sealed the moment it is given. The page says whether the answers the attestation sets out still match what was recorded.
- **An outdated register**: when the folder was reopened after the closure, the page says so. The register is still authentic, but it describes the folder as it stood then.
- **The file is not kept**: it is used to compute its fingerprint, then deleted.

## Checking a seal without Kolinea

Each answer to a sign-off carries a seal: an Ed25519 signature of a message that sets out the decision, its date, the document's fingerprint, the identification method, the IP address, the browser, the channel of a relay and the answer's identifiers. The "Sealed data" annex of the attestation prints that message and its seal. The page publishes Kolinea's public key and the steps to check the seal with OpenSSL, on your own machine.

## What it does not do

An authentic document proves it has not changed since Kolinea drew it up, and that the answers it sets out have not changed since they were given. It is neither an advanced nor a qualified electronic signature under the eIDAS Regulation: it is a time-stamped, sealed record of what was recorded.

The page shows nothing the file does not already show, and it limits how many checks can follow one another from the same address.

## Read also

The [sign-off](/en/features/sign-off) page says what each answer records, and [closing a folder](/en/features/closing-and-archiving) what its register contains.