NOTE that Digital Signature facility is available only for Microsoft Office Xp [2002] or higher. And you can also use the Digi-Seal™ system to sign documents too.
Open the document that you want to check
1. On the Tools menu, click Options to display the Options dialog box.
2. Click the Security tab.
3. Click Digital Signatures button.
4. In the Digital Signature dialog box you will see a list of all Digital Certificates applied to the document along with the relevant dates they were added on.