Skip to content
SignClearly

Check a signed PDF

A PDF signed with SignClearly has two digital signatures. Adobe Acrobat and Reader check both and show whether the file changed after signing.

What is in the file

  • The signer's signature. It is made with a key created in the signer's browser for this one document. The certificate for that key is issued by SignClearly and shows the signer's email address. If the sender asked for an ID check, it also shows the name from the signer's ID.
  • The SignClearly seal. SignClearly adds it after the signer signs, over the whole final file, including the event log page. It stands for SignClearly, not for a person.

Both carry a timestamp from DigiCert, so the signing time does not rely on our server clock.

Why Adobe shows the identity as unknown

Adobe trusts certificates from its own list of certificate authorities and from the EU trusted lists. SignClearly issues its own certificates and is on neither list. Adobe still checks that the file has not changed. To make it trust the certificates too, add the SignClearly root certificate as shown below. You do this once on each computer.

SignClearly root certificate

Name
SignClearly Root CA
Valid until
28 Oct 2046
SHA-256 fingerprint
43c834d551231a81d8cfd940eda1fafb6cb59a0738ca96a016c323840e281859
Download r1.crt

Before importing, compare the fingerprint of the downloaded file with the one above. The two values must match.

On a Mac, in Terminal:
shasum -a 256 r1.crt
On Windows, in Command Prompt:
certutil -hashfile r1.crt SHA256

Trust it in Adobe Acrobat or Reader

  1. Open Preferences: Menu → Preferences on Windows, Acrobat → Preferences on a Mac.
  2. Choose Signatures. Under Identities & Trusted Certificates, click More.
  3. Select Trusted Certificates and click Import.
  4. Click Browse and choose the r1.crt file you downloaded.
  5. Select SignClearly Root CA in the list and click Trust. Tick “Use this certificate as a trusted root”, click OK, then Import.
  6. Close Preferences and open the signed PDF again. The bar above the document should say “Signed and all signatures are valid.”

What “valid” means

The file is exactly what was signed and sealed, and both certificates lead to the SignClearly root. If Adobe says the document was changed after signing, you have a different file from the one that was signed. Ask the sender for the copy they downloaded from SignClearly.

A valid signature is still not a qualified electronic signature (QES). Whether a signature is accepted depends on your country and the type of document.