This essay consists of a CRC tutorial and a way of how to reverse it. Many Coders/Reversers don't know exactly how CRC works and almost no one knows how to reverse it, while this knowledge could be very usefull.

First the tutorial will learn you how to calculate CRC in general, you can use it as data/code protection.
Second, the reverse part will learn you (mainly) how to reverse CRC-32, you can use this to break certain CRC protections in programs or over programs (like anti-virus).

There seem to be utilities who can 'correct' CRCs for you, but I doubt they also explain what they're doing.
I'd like to warn you, since there is quite some math used in this essay. This wont harm anyone, and will be well understood by the avarage Reverser or Coder.
Why? Well. If you dont know why math is used in CRC, I suggest that you click that button with a X at the top-right of this screen. So I assume the reader has knowledge of binair arithmetic.

This is a small, and by no means complete, digestion of some crypto technics.

Level : beginner

Here's a tutorial dedicated to gamers :)

We will write a trainer for this tiny little game called Soukoban.


                                    

Level : newbie

Intro:
You all probably know about the windows file protection? No? Let me explain. The files in the directory system32(or system) are critical for windows. Therefore, windows has it own file protection system managed by sfc.exe. (Start -> Run -> cmd.exe -> sfc.exe and you see its parameters). This file is activate during windows. It checks if the files are the original ones, otherwise, the not original files get replaced by the original ones.

Level : intermediate

Overview:
Author of yoda-protectors is back! This time he brings us ntkrnl protector =)

This is a powerful protector, however protection options are weakly implemented
making it relatively simple to unpack.

Note, if anyone can provide me with a file protected by more high level
VM/metamorphism/emulator options, I would be very happy :D