What verification proves

A check of a signed PDF shows whether it changed after each signature, whose email address each signature is tied to, and in what order people signed.

Every Sovrasign document carries its own evidence inside the PDF. A check reads that evidence and tells you four things.

1. Nothing changed after each signature

Each signature covers the whole document as it was at that moment, including the signatures before it. If anyone changed even one character afterwards, the check says the document is not intact.

2. Who signed

For each signer, the PDF holds a confirmation that the person controlled a given email address when they signed: a sign-in with Google, Microsoft or Apple, or a one-time code that Sovrasign emailed to that address. That confirmation is tied to this exact document, so it cannot be copied into another one. The check tests it against the keys those providers published at the time (the trust list).

The person who prepared and sent the document is recorded the same way: when they select Send, Sovrasign's own identity service confirms which Sovrasign account prepared it.

3. The order and what each person added

The check lists each step in the order it happened: the sender preparing the document, then each signature, with the fields that person filled in.

4. When

Each signature records when it was made. Today that time comes from the signer's device clock, and the check says so ("not independently confirmed"). The evidence still bounds it: a signature was made after the signer's sign-in, and before any trusted timestamp added later. The consent each signer gave to sign electronically is recorded with their signature, with the version of the disclosure they read.

Trusted timestamps come from an independent time-stamping authority: on every signature on paid plans, and one for the whole document when a Free envelope completes, which bounds its signing times.

What a check does not prove

That the signer read or understood the document, or that it is fair or enforceable. See Legal validity.
Who the person is beyond the email account: there is no check of an ID document.
That the signer was the only person with access to that email account.

Each signature also carries an assurance level, from L1 to L5, that says what the identity rests on: L1 an email code, L2 a sign-in with an account such as Google. See Read a verification report.

Independent of Sovrasign

The check runs on Sovrasign's own signing engine, in your browser. You need no Sovrasign account to run it, the file is not uploaded, and the evidence is in the PDF itself, so it stays checkable even if Sovrasign stops. See Verify a signed PDF.