Protecting my code from reverse engineering

Question

As discussed in similar questions here and here I want to protect my code from reverse engineering.

My situation is as Simucal describes in his (excellent) answer h

Answer 1

one option is to use the license key and/or hardware fingerprint to decrypt the sensitive code at runtime and emit it as IL; this will make it invisible to static reverse-engineering tools (e.g. Reflector)

also detect the presence of a debugger and refuse to run in debug mode, except possibly in very limited circumstances (i.e. on your machine)

note that this will make debugging very difficult for you, and nearly impossible for others (if this is an end-user app that's not a problem, but if it is a library or framework for other developers to build upon, that's a problem)

note also that making a copy of physical memory to disk and using offline tools on the memory-dump will reveal your decrypted algorithm, so it is fairly easy to defeat - but far more trouble than most people will bother with

the whole thing is a trade-off between difficulty for you vs deterrence for the few bad apples vs potential loss due to theft/plagarism

good luck, and let us know what you decide!