My copy protection was made for a niche high quality Atari ST graphics program that only got sold in very small numbers. The developer (my customer) want to get sure he really get money for every copy. And I put a lot of effort into randomization of my copy protection detection software. I want get sure nobody developed an automatic cracking program for my copy protection. But I left a easy to find exit point where cracker could easy remove my copy protection detection software. Manually. That worked. Everything can be cracked. But my copy protection got never in deep analysed because I made it really really hard to do it.