Digital Signatures for Adobe PDF Files

Digital signatures can be attached to PDF documents as proof that you are the author and that the document was not altered by someone else.

A digitally signed PDF will have a notation in it that it was digitally signed, usually a scan of a signature or just text with the author's name, with an Adobe logo watermark in the background.

If you don't already have a certificate, please visit the Digital Certificates page.

Configuring Adobe Acrobat Reader

This procedure should be the same for other Adobe products such as Acrobat Professional.

Before continuing, ensure you have imported your certificate into either the Windows Certificate Store or the macOS Keychain. If you have not already done so, use the following instructions for your operating system:

To check if your certificate is visible to Adobe Acrobat Reader, and to make it the default:

  1. Open Adobe Acrobat Reader.
  2. Open the "Preferences" window.
    • On Windows: Select the "Menu" button in the menu bar, then select "Preferences...".
    • On macOS: Select "Acrobat" in the menu bar, then select "Preferences...".
  3. Select "Signatures" in the "Categories" pane.
  4. In the box labeled "Identities & Trusted Certificates", click "More...".
  5. Select the "Digital IDs" section if it is not open already.
  6. In the list of certificates, find the certificate you want to use.
    • A UBIT email certificate will contain your email address in the "Name" field, but it may not contain your name. When selected, "Email Protection" should be listed as an intended usage in the description pane.
  7. If you cannot find the certificate you want to use, refer to the instructions for importing a digital certificate.
  8. Select "Usage Options" (which may only appear as a pencil icon), then select "Use for Signing". A blue pen icon should appear next to the certificate in the list.
  9. Close the certificate settings window, then select "OK" in the preferences window.

Signing a PDF Document

Adding a signature should always be the last change made to a document.

Making any further changes after signing a document will invalidate the signature.

To sign a PDF document using a certificate:

  1. Open a PDF document in Adobe Acrobat Reader.
  2. In the "All tools" menu, select "Use a certificate".
    • This option may be hidden until "View more" is selected.
  3. Select "Digitally Sign".
  4. Follow the presented instructions to specify where the signature should appear.
  5. Select the certificate that should be used to sign the document and select "Continue".
  6. Select how you want your signature to appear.
    • If you select the "Create" button, you will be able to create a new signature appearance, which may include an image of your signature or a simple text signature.
  7. Click "Sign" to sign your document.
  8. You will be prompted to save the signed copy of your document as a new file. Choose where to save it.
  9. You may be prompted multiple times by the operating system to approve use of your certificate by Adobe Acrobat. Enter your login password to finish signing the document.
    • Your operating system may offer to always allow Adobe Acrobat to use your certificate. Since digital signatures are legally binding in some situations, you may want to refuse this option so that you always have to enter your password when signing a document.