Create a Digital Signature in Excel First things first, to create a digital signature, you must have a signing certificate, which proves identity and verifies the authenticity of the document.

Want to protect an important Word document or Excel spreadsheet? Here's how to add a password, make documents read-only, and tap into other tricks to safeguard sensitive files.

If the Signature Line option is greyed out in Excel or Word on your desktop, remove editing restrictions or add a signature line manually.