Is it possible to convert a dll library back to source code?
Not that I want to do this, but I need to outsource some non-critical parts of a software that I am writing, but I wouldn’t want the other guys to copy everything that I have so far.
The code in the respective dll is not the whole code. I have managed to include only the necessary code in the library, but I still wouldn’t like the other guys to copy my code.
Should I be worried?
Possible? Yes.
Easy? It depends.
If you have written your dll in .NET, decompilation is a snap, using tools like Reflector, unless you have obfuscated your code.
Even if this is not .NET code, it is still possible, though much more difficult. And you can make things more difficult if you do obfuscate your code with one of the existing tools.
In general, if you give your code (compiled or not) to someone, they will be able to decompile it from the assembly/bytecode, even if it is obfuscated.
This is not always easy, and normally too much effort. It really depends on how paranoid you are and how valuable your code is to the third party.
There is no protection from a truly determined attacker. It can take them years, but if they are truly determined, they will figure it out.