15. July 2002
Standard Zip Encryption is Weak!
Some people might ask why not adding standard zip-encryption. Well, first of all the standard zip-encryption has not been strong enough for modern computers, and there are hacker tools that even a half-literate computer-user can use to crack the password of a zip-archive. In other words: ** every encrypted zip file can be cracked using freely downloadable helper tools **. That's because standard zip encryption is weak regarding modern personal computer power. Furthermore, adding real encryption is a heavy weight that many people do not need, see the last argument for seeing the standard one is useless anyway, and adding a non-standard one should not be the case of the standard zziplib either, ye know.
On the other hand, obfuscation is a means to fear off half-literates just as well - there are no premade tools for the obfuscation you can invent from the xor examples. And a hacker that can de-obfuscate such a dat-file is able to dissassemble your program as well - just to remind you that the disassembly of a program will reveal the decryption routine and the decryption key, even for a heavyweight crypt algorithm. Although there is a difference, it just ranges on about times and exprience, not magnitudes. Remember the old saying: you can irritate some people for some time but not irritate all people for all the time. As for encryption of artwork and AI scripts in games and applications, just keep in mind that the final recipient has the decryption key on his system anyway, just obfuscated. So each such encryption is nothing more than just a clever form of obfuscation, nothing mathematical strong.
Some other people might ask why to obfuscate anyway. Well, the reason is theft. Even people who write opensource free software generally like to get some reward for what they do, some fame or atleast some sweet dream to have helped the world go a bit easier in the future. As for program text this is quite natural for the programmers who pick up some code from somewhere else - it happens that most of them have gone through some formation and they know how hard it is to get even some lines of code out of your brain. This is not the case for some artwork and AI parameters, people do not have much respect for those - they just pick it up, put it under their umbrella, and that's it - they even claim they could have done that themselves, and in most cases it is that they never have been really trying to do it and think of it as being comparable to that action-art they've seen on TV.
Just be sure that there is nothing wrong with obfuscating things for a binary distribution of your program even for the opensource case - the program text itself is an obfuscation in its source form when being compiled into cpu instructions. Still, the interested people can get hold of the source code since you provide it somewhere and actually the original programmers like to hear from literate people who could help with modifying the project. The same is true for you artwork and AI scripts, the interested people can still see them in the opensource project material, but only those will look who dare to, not just the halfwit next door.
Well, you do not need to that on the other hand - ID software has shown that it can be very helpful since people will start to write new maps and new bots, pack them and publish them. An open data format is a form of attraction for people who can use a graphics program and an editor but who do not know how to program. And if you use obfuscation within an opensource program, it is surely enought to just use the xor-format presented here, so that it easy for third people to get involved if they want to, they just have to rewrite their new datapacks with zzxorcopy, and that's it.
As for the non-opensource projects, be aware that there are some ways to even staticlink the zziplib into your project, so you can even hide that you used zip tools to create your dat files. This is well enough for anyone to do - as soon as a hacker will get to the point to notice you used a zip format, he would have had found any other deobfusation or decryption routine as well. If you are frightened, just encrypt the executable with tools you bought from somewhere else. On the other hand, should there be problems or bugs, you have an easier time to find them when they could be caused by your dat entries, and it is again easy to send a fixup file to your clients, since the command line tools are just a breeze compared with some other anti-hacking tools you'll find on the market.
Well, hope this is enough rationale to tell you that I do not see a need to implement anything more than obfuscation within zziplib - if you need real encryption, use real encryption software and its fileformat that supports it, not zip files.