So i'm trying to reverse an unity game using il2cpp to get the assets of it.
After some reverse stuff i found that the asset's (especially here the png image) byte array get encrypted with a key and i need to use that key and the DecryptByteArray function to get the real data of the image but when i try to look at the DecryptByteArray in dnspy i got this: 
Technically this is not the right decrypt function and it also doesn't contain the function or code line where it is used.
So i decide to take a look at the assembly code to see what's the real function and what's the key but then i found out the the reference of that method is just the data offset: 
and the runtime function define: 
And when i go to pseudocode it show up like this
which i think it's not really matter but i'm not sure am i right or not.
So i want to get some help to find the key of the encryption and if u can please help me with the DecryptByteArray function too cause i'm not good at assembly so it might took me at least 3 weeks if i wanna understand what is that assembly code doing.
Here's the client of the game.
