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Commercial Certificate for digitally signing macros

Posted on 2007-03-26
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Last Modified: 2012-08-14
Where do I get a commericail certificate and why kind of certificate to a get digitally sign a macro for Excel.
I called my vendor GeoTrust and they said they don't [provide that kind.
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Question by:svenswenson
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zorvek (Kevin Jones) earned 500 total points
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An unofficial digital certificate can be added to an Excel workbook so that, after a one time interaction with the user where the user either allows or disallows that digitial certificate, the user can then repeatedly open the workbook and run macros without any warnings at all, even if their security setting is high. An extended description of how to create and use digital certificates can be found at http://pubs.logicalexpressions.com/Pub0009/LPMArticle.asp?ID=194. A brief tutorial is included below.

To create a free unsecure code-signing digital certificate locate and run SelfCert.exe. It is an optional utility installed as part of the Office installation found in the Office installation directory. If not found, open the Add/Remove Programs control panel, run the Office Installer, and install Digital Signature for VBA projects under Office Tools. When run SelfCert asks for a name - enter any meaningful name or description. The text entered is displayed to the user whenever they are asked to accept or decline the digital certificate. For more information see http://support.microsoft.com/default.aspx?scid=kb;en-us;Q217221.

Once the digitial certificate has been created on the development system, open the workbook and press ALT+F11 to open the VBE. Select the menu command Tools->Digital Signature. Click Choose and select the desired digital certificate (they are listed by name.) Click OK. Click OK again. The workbook now contains a digitial signature. Since the development system already has the digital signature installed, the workbook will now open on that system without any macro warning prompt.

To allow the workbook to run without the macro security warning on another system the digital certificate has to be installed on those systems as well. Copy the workbook to a target system and open it. Excel will present the Security Warning dialog. Click Details to show the Digital Signature Details dialog. Click View Certificate to show the Certificate dialog. Click Install Certificate. Click Next twice and then Finish. Click Yes when the prompt is displayed asking if the certificate should be installed. Click OK on the completion dialog. Click OK twice more to close the widows. Click Enable Macros on the Security Warning to open the workbook. In the future any workbook with that digital certificate installed will open without a macro security warning.

Since it is relatively easy for someone to forge an unsecure digital certificate and place it in a malicious workbook, this method of avoiding macro security warnings may not be an acceptable solution. In the event that a decision is made to abandon this technique the installed digital certificates can be easily removed by opening the Internet Options dialog from either Internet Explorer or from the control panels and navigating to the Content tab. Click on Certificates. Find the certifcates to be deleted (they should be in either the Trusted Root Certification Authorities or Other People section,) selecting them, and click the Remove command button. Click Done when finished.

If true security is required then a secure digital certificate can be purchased from any of the many Certificate Authorities. See Microsoft's list of Certificate Authorities at http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnsecure/html/rootcertprog.asp.

For more information on macro security settings in Office, see http://office.microsoft.com/en-us/assistance/HA011362661033.aspx.
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