Win32 Debug Protection Idea

If you want more ideas, study commercial packers like arma, aspr, and alike - they have lots tricks inside and some of them are really interesting. If you'd like to make it a little bit harder, try also utilize SEH - then it is real fun.
One interesting idea from one crackme I've heared of is this - it used SEH with singlestep exception; executed one instruction, overwrited the place with another one, executed it, then overwrited it with third,... quite messy to debug I think There are unlimited posibilities...
Good luck,
least

PS. look to the ^DAEMON^'s cave, here are loads of tricks...

i'm am rather happy with my current solotion... i don't want my crackme to be all just anti junk i am more looking for good ideas and less anti everything hehe.

right now i am working on a key system, i am thinking i will go with key files and ECC crypto but there are very few practical tutorials on writing a key system and the ones that are around are very poor and very easy to keygen.

reversing other peoples projects is a great source of ideas, but i am more on the protection side of the fence, just because i see my self as being more creative, so my reversing is not great.. but it gets me by.. you gotta ride the fence to get good at ether side aye.

offtopic:
(dont wanna create a new topic)

has anyone seen any interesting crackmes using public key encryption? (good examples... not like the old keygenable armadillo system which seemed useless)

Armadillo uses Public Key Kryptosystem from 3.61 and v10 Keys Version only.

[Darren]

http://www.certicom.com/index.php?action=ecc_tutorial,home

might help you get some understanding of ECC

- Darren

[SiNTAX]

Originally Posted by least

One interesting idea from one crackme I've heared of is this - it used SEH with singlestep exception; executed one instruction, overwrited the place with another one, executed it, then overwrited it with third,... quite messy to debug I think There are unlimited posibilities...

Hardly a new idea.. (I remember Rob Northern Copylock on Amiga used that, back in 1990 or maybe even earlier)

Getting around that isn't that hard either.. ie if you patch the decryption routine to store the unencrypted code copy somewhere else and then dump it to have a look at it. (or use a tracer that can trace through it)

I think the best way would be to use Ring 0 code to change the INT 1/3 handlers (by patching the IDT) to something in your own code. No debugger can possibly avoid this.

Best regards,
Alex Ionescu
http://www.relsoft.net