Add a digital signature to a file or a VBA project

You can obtain a digital certificate from a commercial certification authority, such as VeriSign, Inc., or from your internal security administrator or Information Technology (IT) professional. Or, you can create a digital signature yourself by using the Selfcert.exe tool.

To learn more about certification authorities that offer services for Microsoft products, see the list of Microsoft Root Certificate Program Members, on the MSDN Web site.

 Notes 

• The hyperlink (hyperlink: Colored and underlined text or a graphic that you click to go to a file, a location in a file, a Web page on the World Wide Web, or a Web page on an intranet. Hyperlinks can also go to newsgroups and to Gopher, Telnet, and FTP sites.) in this topic goes to the Web. You can switch back to Help at any time.
• Because a digital certificate you create yourself isn't issued by a formal certification authority, VBA projects signed (macro project: A collection of components, including forms, code, and class modules, that make up a macro. Macro projects created in Microsoft Visual Basic for Applications can be included in add-ins and in most Microsoft Office programs.) by using such a certificate are referred to as self-signed projects. Depending on how Microsoft Office digital-signature features are being used in your organization, you might be prevented from using such a certificate, and other users might not be able to run self-signed macros for security reasons.

• If you want to prevent users of your solution from accidentally modifying your VBA project and invalidating your signature, lock the VBA project before signing it. Your digital signature says only that you guarantee that the project has not been tampered with since you signed it. It does not prove that you wrote the project. Locking your VBA project doesn't prevent another user from replacing the digital signature with another signature. Corporate administrators might re-sign templates (template: A file or files that contain the structure and tools for shaping such elements as the style and page layout of finished files. For example, Word templates can shape a single document, and FrontPage templates can shape an entire Web site.) and add-ins (add-in: A supplemental program that adds custom commands or custom features to Microsoft Office.) so that they can control exactly what users may run on their computers.
• If you create an add-in that adds code to a VBA project, your code should determine if the project is digitally signed and notify the user of the consequences of modifying a signed project before continuing.
• When digitally signing macros, consider obtaining a timestamp so that others can verify your signature even after the certificate used for the signature has expired. See Microsoft Office Online for more information on macro security and timestamps.