> TDL-4's makers created their own encryption algorithm

Well, they could simply be using more than one algorithm. They could use AES as the main one and then re-encrypt everything with their own algorithm. If cryptographers break through their own created algorithm (probably just a variation of 3DES or AES) then they still have to break through the standard AES. I would be surprised if they were not doing something like this. As you say, everybody knows that you do not create your own algorithm. However, layering it with different algorithms, would probably be a good idea and it would make cryptographers work a lot harder (maybe?)

Although if the keys are as easily accessible as they say then I agree with you, what is the point?