How to protect wsp file so no one can read my source code. When we change wsp file extension from wsp to zip, it gives all dll file and this dll can be extracted from .net reflector and get all source code. Is there any way to protect my code ?
If you don't want other people to be able to Reverse Engineer the source code to DLLs you're giving them, then you should obfuscate the DLL. See .Net Obfuscation for some suggestions.
But before going in that direction I have a couple of comments: