cuda won't help either. there are many encryption algorithms that are extremely safe and theoretically not crackable like techmuc has already mentioned. maybe in the future with quantum computers.

...but all of this doesn't matter much. with tools like glintercept (forgot the names of the many directx pendants) you can simply grab meshes, textures, shaders from graphics ram for example and there also are tools for grabbing stuff from system ram.

3d ripper dx for dx9,

also one can read the pc ram and search for mdl signatures and rip from there? (i mean if you are worrying that they would search for the key in exe, they would do this too.)

So it doesnot really matter much. just make it to have good compression/speed ratio.

Putting the key in the executable is a bad idea. If you do this the choice of encryption algorithm does not play a role as the system itself is senseless. Provide a funtionality for entering the key via an api or via a textbox. All other methods are insecure.

you cannot expect player to input a key for the game to run. In fact it's even worse, when the user knows the key he/she can hack the resouces easier. Key HAS TO be in the exe.

In fact if the algorithm requires a key, some way other it will be used somewhere in your app, which if you look from this point, is always hackable.

It's rather more logical to use a harcoded function as key instead of a number/string.

Even after all this, files will be decrypted to ram, which defies the use of the encryption.