right. but, again, the whole system doesn't even rely on entropy. i was referring to existing literature as an analogy to, perhaps, better clarify the idea. it seems i was mistaken doing so.
http://www.faqs.org/faqs/cryptography-faq/
It might be an idea to read about different attacks - known plaintext etc - and seein if your system is still secure. (It won't be, so if you can't find the flaw you know you need to look more).