A strongName consists of the assembly's identity—its simple text name, version number, and culture information (if provided)—plus a public key and a digital signature. It is generated from an assembly file (the file that contains the assembly manifest, which in turn contains the names and hashes of all the files that make up the assembly), using the corresponding private key. Microsoft® Visual Studio® .NET and other development tools provided in the .NET Framework SDK can assign strong names to an assembly. Assemblies with the same strong name are expected to be identical. (Microsoft MSDN).
In this article you'll see how to remove StrongName (simply SN) in .NET EXEs and DLLs. Also you'll learn something about cracking IL codes.