I've been looking at the How To Crack C.1/2/3 for a while now, attempting to figure out the Instant Access protection scheme. Unfortunately, the third section doesn't have a full breakdown of the cracking method as +ORC had done in his other tutorials.

I can see how the registration code is changed into the "magic" code, but I don't see how the access code is generated from it (the product code also appears to be randomly generated, which doesn't help).

Any clues? I'll admit this is quite an old target, but it's quite hard to beat. ???