Varin Varin - 1 month ago 18
ASP.NET (C#) Question

Unable to run Excel VSTO Add-ins

Trying to run an Excel 2013 VSTO Add-ins project, and I keep on getting an error that says that:


"System.Security.SecurityException: The solution cannot be installed because it is signed by a publisher whom you have not yet chosen to trust. If you trust the publisher, add the certificate to the Trusted Publisher list."


The project has a key file with signature algorithm sha256RSA and certificate issued to/by the Windows User.

Any idea how to get around this ?

Answer

Try the solutions from the postings here.

As for myself, I've developed an Excel VSTO AddIn with a self-signed untrusted certificate that is delivered by a custom Setup.exe which is then installed on machines that belong to some end-users. I have no control over these machines because the end-users just download my Setup.exe from a public website. After setup the path of the .vsto is a local file path so I don't need a web server as a host.

In my case the following code (placed in my Setup.exe) is enough to successfully trust the Excel VSTO:

UserInclusionList.Add(new AddInSecurityEntry(new Uri(vstoFilePath),
    "<RSAKeyValue><Modulus>...</Modulus><Exponent>...</Exponent></RSAKeyValue>"));

The corresponding <RSAKeyValue> can be found in your .vsto file.