Question

What happens exactly when I launch a .NET exe? I know that C# is compiled to IL code and I think the generated exe file just a launcher that starts the runtime and passes the IL code to it. But how? And how complex process is it?

IL code is embedded in the exe. I think it can be executed from the memory without writing it to the disk while ordinary exe’s are not (ok, yes but it is very complicated).

My final aim is extracting the IL code and write my own encrypted launcher to prevent scriptkiddies to open my code in Reflector and just steal all my classes easily. Well I can’t prevent reverse engineering completely. If they are able to inspect the memory and catch the moment when I’m passing the pure IL to the runtime then it won’t matter if it is a .net exe or not, is it? I know there are several obfuscator tools but I don’t want to mess up the IL code itself.

EDIT: so it seems it isn’t worth trying what I wanted. They will crack it anyway… So I will look for an obfuscation tool. And yes my friends said too that it is enough to rename all symbols to a meaningless name. And reverse engineering won’t be so easy after all.

Answer 1

If you absolutely insist on encrypting your assembly, probably the best way to do it is to put your program code into class library assemblies and encrypt them. You would then write a small stub executable which decrypts the assemblies into memory and executes them.

This is an extremely bad idea for two reasons:

1. You’re going to have to include the encryption key in your stub. If a 1337 hacker can meaningfully use your reflected assemblies, he can just as easily steal your encryption key and decrypt them himself. (This is basically the Analog Hole)
2. Nobody cares about your 1337 code. I’m sorry, but that’s tough love. Nobody else ever thinks anyone’s code is nearly as interesting as the author does.