SmartAssembly can add an attribute to your assembly that prevents Microsoft's Common Intermediate Language (IL) Disassembler (ildasm.exe) from opening your assembly.

To prevent disassembly of the IL, in the Project Settings window, go to Other Protections or click the icon in the toolbar.

Select I want to prevent Microsoft IL Disassembler from opening my assembly.

If you enable this option, some debugging tools will no longer work with your assembly. 

When either of the 'Other Protections' options are enabled, the colored bars under the toolbar icon and to the left of the feature options are green. If both of them are disabled, the bars are orange.