I mean sure you could in theory, but in practice that's not how common built-in random number generators work.

I was responding to:

> chances are the length of the seed is equal to the length of the original file

And why would the chances be that? You'd really have to go out of your way for that. I don't even know if there are libraries that can handle a seed and state length on the scale of megabytes. No, chances are 99.99+% it used a seed of a few bytes, because that's how common random number generators designed for efficiency work.