Getting null from GetHostEvidence()

Question

I'm trying to follow http://msdn.microsoft.com/en-us/library/bb763046.aspx to create a sandbox to run untrusted code.

When I execute this in my Sandboxer class:

StrongName fullTrustAssembly = typeof(Sandboxer).Assembly.Evidence.GetHostEvidence<StrongName>();

I will get null returned. Why? How do I fix it?

Answer 1

You must sign your application. The easiest way to do it is:

1. Right click on your project in the Solution Explorer and select Properties
2. Go to Signing tab
3. Check Sign the assembly
4. From drop box, select <New...>
5. Type a name in Key file name
6. Password is optional, so you can uncheck Protect my key file with a password
7. Click Ok

Run the Run Partially Trusted Code in a Sandbox sample again. It should work.

Answer 2

According to the page you linked, all of the calls to GetHostEvidence<T>() are being supplied with StrongName as the type parameter. If the assembly doesn't have a strong name (not all do), it will return null.