| Microsoft Office 2000/Visual Basic Programmer's Guide | |
Office 2000 uses Microsoft Authenticode technology to allow developers to digitally sign VBA projects in their documents, templates, and add-ins by using a digital certificate that identifies the developer as a trusted source. In conjunction with this ability, Word, Excel, PowerPoint, and Outlook have security-level settings similar to those in Microsoft Internet Explorer, which allow users to identify code produced by trusted sources and ensure that signed code hasn't been altered.
To produce a trusted solution, you need to obtain and install a digital certificate that you can use to digitally sign the VBA projects in Word, Excel, PowerPoint, and Outlook solutions to identify them as your work. When opening a signed document, Microsoft Office applications can verify a digital signature to determine if the signed VBA project has been altered in any way, and automatically disable macros that might have been altered by a macro virus.
Note Digital signing works with Office installations only on computers that also have Internet Explorer version 4.0 or later installed. The digital-signing and signature-verification features in Microsoft Office will not work at all on computers that have Internet Explorer versions 3.x or earlier, any version of Netscape Navigator, or any other browser installed. If a user attempts to digitally sign a VBA project on such computers, a message informs the user that this feature is not available without Internet Explorer 4.0 or later installed. When opening any document that contains macros (signed or not) on such computers, the Office application displays a standard macro virus dialog box that allows the user to choose whether to enable or disable macros before opening the document.
The following sections discuss the concepts and technology behind digital signing and how Word, Excel, PowerPoint, and Outlook use this technology to identify a trusted solution.