Digital Certificates

Code Signing

Code Signing Certificates use a unique cryptographic algorithm to bind the identity of the publisher to the software.   Once code has been digitally signed, customers can be sure of the identity of the software vendor and that the application has not been corrupted.   Security warnings that appear with unsigned code are replaced with notifications regarding the software publisher’s identity and that this represents a trusted source.

Why it matters

Signing code adds an essential layer of trust to the download and usage of a Microsoft Office program.   Beyond this consideration, there are some additional practical applications that may be important to some users depending on the specific security environment in which you are using Microsoft Office.   For instance, some companies may choose to disable all macros in Office products (such as Excel, Word, PowerPoint, etc.) in order to completely protect them from outside attacks from malicious coding.  There are essentially four options at which your Office product can be set at in determining whether macros will be disabled or enabled.   These are shown below:


Of the four options shown above, the first will disable macros absolutely.   The second and fourth options will enable macros.   And the third option is something of a hybrid; macros will be disabled unless the file opened comes from a trusted source and this is attested by a digital certificate.   The Excel Converter workbook is embedded with a digital certificate that will allow you to choose this third option.   Note: Whichever option that is selected to enable/disable macros, the checkbox must also be checked allowing Trust access to the VBA project object model.   If not, macro code will still not be enabled for operation.   Therefore, the Excel Converter workbook will work correctly if the VBA model is checked and either the second, third or fourth Macro Settings option selected.

Implementing the Digital Certificate

If you have chosen the option to Disable all macros except digitally signed macros, you will notice the following security warning when opening the Excel Converter workbook.


Click on the Options button to begin enabling macros using the Digital Certificate.   The following dialog box will display:


Trust all documents from this publisher.    Selecting this option will allow you to open and use the Excel Converter workbook with macros.   The dialog above will not display when opening the Excel Converter application in future.   Macros will remain disabled for all other applications that do not contain a similar digital signature that you have accepted as being from a trusted source.

Enable this content.    Selecting this option will allow you to open and use the Excel Converter workbook with macros for a single session.   The next time that you open Excel Converter, the same dialog will display and you will be required to select an appropriate option.

Help protect me from unknown content (recommended).    This option may be a bit confusing, especially the “recommended” part.   Basically, if this option is selected you are totally protected — but macros remain disabled and you cannot run code nor use Excel Converter in any way.   Choosing this option would be analogous to clicking the Cancel button.