Sign Microsoft Word Documents with S/MIME Certificate

You can add a trusted digital signature to your Microsoft Word documents for an extra layer of authenticity and security.

What You Need:

Not all S/MIME certificates include document signing capabilities. You need a certificate that is classified as “multi-purpose” and not just “strict”. Any of the following certificates will work:

• Sectigo or Comodo Personal Authentication Pro
• Sectigo or Comodo Personal Authentication Enterprise
• DigiCert S/MIME for Individuals (also known as Class 1 DV)
• DigiCert S/MIME for Business (also known as OV)

The Basic Personal Authentication Certificate is not capable of document signing.

How to Add Your Signature:

1. Open the Microsoft Word document you want to sign.
2. Click File in the top-left corner of the window.
3. In the File menu, click on Info.
4. On the Info page, click the Protect Document button.
5. From the drop-down menu, select Add a Digital Signature.
6. The Sign window will pop up:
   • Commitment Type: Select a reason for signing from the drop-down menu.
   • Purpose for signing this document: Type any additional information here.
   • Details: In this area, you can add the signer’s title and organization details.
   • Change Certificate: If you have multiple certificates installed, Word might select one automatically. Click Change to select the correct S/MIME certificate from your computer’s certificate store.
7. Once you’ve selected your certificate and added any optional details, click Sign.

Adding your digital signature finalizes the document. If you need to make any changes to the document, the signature will be removed.