Suppose I wanted to write a protection system for Linux or another Unix. Wrappers would not be very practical, let's say, so I'm going to go with SDK-style library calls.

What are some of the more practical ways to obfuscate code and implement licensing that is SDK-based? It seems it would be much easier to RE such a scheme, so there would have to be other ways of protecting the algorithms, right?

hi corus-corvax,

pls may i ask what kind of protection you allready searched for?
when about "protection" SDKs i have not yet really looked for it on linux, or better - all i saw was more or less BS and worked on very limited systems with 100s of specific requirements. burneye is such an example. nice in theory but it simply does not work on all of my systems haha so i left these things.

i think in order to write what you are up to, one should have a proper idea of what he plans. do i see it right you are in a kind of brainstorm/evaluation phase?

search on http://www.phrack.org/ there is plenty of stuff related. also i guess studying the ELF file format in its very details is unavoidable
also we fight with userland exec nowadays as well - so you can not rely your prog is executed by the OS process loader - just a thought to consider

also on http://felinemenace.org/papers/Binary_protection_schemes-1.00-prerelease.tar.gz

you find a paper from andrewg about binary protection schemes + SOURCE CODE *gggggggggg*

on my personal page you might also find places of interest: http://home.pages.at/f001

i would love to keep the discussion going - so pls just post your thoughts

good luck and
regards, 0xf001

Hi 0xf001,

Thanks for your reply. It doesn't seem like this forum is generating a lot of interest in Linux/Unix reverse engineering/protection.

I'll check out the links you posted. I'm not super-familiar with a lot of Linux-specific stuff, since I run FreeBSD, but the principles are similar - calling a library to verify a license while making it more difficult for someone to trace and reverse.

I'll post my comments here after I do some more reading!

c-c