Apply a Digital Signature to a Document

Normally, you sign a (paper) check to authenticate its validity to the recipient (and, in due course, to your bank). Similarly, you can apply a digital signature to a Word document to authenticate its validity.

If your computer already has one or more digital IDs installed, you're ready to go; skip ahead to the section "Apply a Digital Signature." If not, you must first set Word up to use a digital signature, as described in the next section.

This feature can be useful for determining whether a document has been changed since the digital signature's holder applied the signature, but because digital signatures are neither widely used nor widely accepted at this writing, applying a digital signature to a Word document doesn't always have the intended effect.

Set Word Up to Use a Digital Signature

To set Word up to use a digital signature, follow these steps:

1. Open a Word document that has been saved. (If you start from a new document, Word will prompt you to save the document.)
2. Click the Office Button, click or highlight Prepare, and then click Add A Digital Signature. Word displays the Microsoft Office Word dialog box shown, warning you that "evidentiary laws may vary by jurisdiction" and that Microsoft "cannot warrant a digital signature's legal enforceability."
3. Select the Don't Show This Message Again check box (unless you want to see this message each time you go to apply a digital signature), and then click the OK button. Word displays the Get A Digital ID dialog box.
4. Choose how to get a digital ID:
   • Get A Digital ID From A Microsoft Partner: Select this option button and click the OK button to open a browser window to the Digital Signing page on the Microsoft web site. Here, you will find a variety of services that provide digital signatures. Most provide a trial of their paid services.
   • Create Your Own Digital ID Select this option button and click the OK button to display the Create A Digital ID dialog box. Type the details of your ID, and then click the Create button. Word creates the digital ID, installs it, and then displays the Sign dialog box. Go to step 3 in the next section.

A digital ID you create yourself via the Create A Digital ID dialog box is useful only for testing. It has no authentication and is worthless in the real world.

Apply a Digital Signature

To apply a digital signature to a document, follow these steps:

1. Finalize the document, and save any unsaved changes to it.
2. Click the Office Button, click or highlight Prepare, and then click Add A Digital Signature. Word displays the Sign dialog box.
3. In the Purpose For Signing This Document text box, type a description of why you're signing the document.
4. If your computer has two or more digital IDs installed, and the Signing As group box shows the wrong signature, click the Change button, choose the correct certificate in the Select Certificate dialog box, and then click the OK button.
5. Click the Sign button. Word closes the Sign dialog box, applies the digital signature, and then displays the Signature Confirmation message box, warning you that changing the document will render your signature invalid.
6. Select the Don't Show This Message Again check box if you can dispense with this message box in future, and then click the OK button. Word closes the message box and displays the Signatures pane.
7. Close the document. (You don't need to save changes-Word has already saved them for you.)