Verify a digital signature

That the signature is mathematically valid, that the signed part wasn't changed, who the signer and certificate issuer are, when it was signed and whether the certificate was valid then. We also show whether the issuer marks the certificate as qualified.

Whether the certificate has since been revoked and whether the issuer is on a trust list — that would require contacting other servers. For an official check of a qualified signature, also use the issuer's tool or Adobe Acrobat Reader.

The signature is valid for the version of the document at signing time, but something was added later (e.g. another signature, a comment or a filled field). That's often normal, but check what was added.