How to sign a MS Office Word document

Getting the signing client certificate

You need a client certificate for signing documents or software/code. That article describes requirements you have to fulfill; see also this summary table. Note the certificate purposes:

Code signing certificate image in Windows 10

Acquiring a certificate using the menu "Client certificates - New" on the CAcert web page, you must check the box "Show advanced options" and the box "Code signing" in advanced options. If you cannot see that box, you do not fulfil all requirements for the ability to ask for such a certificate, or you did not ask for enabling that feature for your account.

New client code signing certificate

Select "Options" from the "File" menu (left side of the main window). Select "Protect document" on the right side. Then select "Add a digital signature".

Find the signing dialog

The signing dialog appears. A suitable certificate is already preselected here. Only if you have no code/document signing certificate, that field is empty. If you do have more such certificates, you can select another one after you press the "Change..." button.

Digital signing dialog

Select <> from the drop-down menu "Commitment type" your action over the document. Also enter the "Purpose for signing this document". You should also add some information about you, after you press the "Details..." button:

Information about the signatory

Enter your information and press OK; the signing dialog appears again. Press the "Sign" button.

The signing itself

You will see the confirmation (you can suppress this dialog for the future). The document is now digitally signed.

Confirmation

After signing, and next time anybody opens the document, the two yellow bars appear at the "Options" page: "Signed document" and "Protect document".

The indication of a digitally signed document

After you press the "View signatures" button, the document window with the rightside pane appears, containing the essential information about the signature(s). You can display details after pressing the "Signature details..." link.

The indication on the right of a digitally signed document

This dialog announces a digitally signed document

The link "See information about the signer", a dialog appears containing the information entered as "Details" in the time of signing .

Signer information