This article describes how you can digitally sign (digital signature: An electronic, encryption-based, secure stamp of authentication on a macro or document. This signature confirms that the macro or document originated from the signer and has not been altered.) a macro project (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 a certificate (certificate: A digital means of proving identity and authenticity. Certificates are issued by a certification authority, and like a driver's license, can expire or be revoked.). If you don't already have a digital certificate, you must obtain one. To test macro projects on your own computer, you can create your own self-signing certificate by using the Selfcert.exe tool.
In this article
Obtain a digital certificate for signing
You can obtain a digital certificate from a commercial certificate authority (CA) (certificate authority (CA): A commercial organization that issues digital certificates, keeps track of who is assigned to a certificate, signs certificates to verify their validity, and tracks which certificates are revoked or expired.) or from your internal security administrator or information technology (IT) professional.
To learn more about certificate authorities that offer services for Microsoft products, see the list of Microsoft root certificate program members.
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Your macro projects and Microsoft Office
Because a digital certificate that you create isn't issued by a formal trusted certificate authority, macro projects that are signed by using such a certificate are known as self-signed projects. Microsoft Office trusts a self-signed certificate only on a computer that has the self-signing certificate added to the Trusted Root Certification folder in the Certificates - Current User store.
To learn how to create a self-signing certificate, see the following section.
Create a self-signing certificate
Windows 7, Windows Vista, or Windows XP
- Click Start, point to All Programs, click Microsoft Office, click Microsoft Office Tools, and then click Digital Certificate for VBA Projects.
The Create Digital Certificate dialog box appears.
- In the Your certificate's name box, type a descriptive name for the certificate.
- Click OK.
- When the SelfCert Success message appears, click OK.
View the certificate by using Internet Explorer
To view the certificate in the Personal Certificates store, do the following:
- Open Internet Explorer.
- On the Tools menu, click Internet Options, and then click the Content tab.
- Click Certificates, and then click the Personal tab.
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Digitally sign a macro project in Excel, PowerPoint, Publisher, Visio, or Word
- Open the file that contains the macro project that you want to sign.
- On the Developer tab, in the Code group, click Visual Basic.
Note If the Developer tab is not available: Click the File tab. Click Options. Click Customize Ribbon. In the Customize the Ribbon list, click Developer, and then click OK.
- In Visual Basic, on the Tools menu, click Digital Signature.
- The Digital Signature dialog appears.
- Select a certificate and click OK.
Note If you haven't selected a digital certificate or want to use another, click Choose. Select a certificate and click OK.
- It is recommended that you sign macros only after your solution has been tested and ready for distribution: when code in a signed macro project is changed in any way, its digital signature is removed. However, if you have the valid digital certificate that was previously used to sign the project on your computer, the macro project is automatically re-signed when you save it.
- If you want to prevent users of your solution from accidentally changing your macro project and invalidating your signature, lock the macro project before you sign it. Your digital signature implies that you guarantee the project has not been tampered with since you signed it. Your digital signature does not prove that you wrote the project. Therefore, locking your macro project doesn't prevent another user from replacing the digital signature with another signature. Corporate administrators can 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 what users run on their computers.
- If you create an add-in that adds code to a macro project, your code should determine if the project is digitally signed and should notify the users of the consequences of changing a signed project before they continue.
- When you digitally sign macros, it is important to obtain a time stamp so that other users can verify your signature if the certificate used for the signature has expired, or has been revoked after signing. If you sign macros without a time stamp, the signature remains valid during the validity period of your certificate.
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