Why has this not been done?

[dave walker]

So when drinking some beer with friends we sometimes come up with crazy 
ideas that should be done, however we normally figure out why it is a 
bad idea.  However, I have had an idea stuck in my mind for about 2-3 
months and can not figure out why it has not yet been done.  I know 
there is randomness in the initial sequence number for TCP packets.  But 
what about making the rest of the packets random sequence.  (read my 
post before saying you can't have random sequence numbers)

I know there is a lot of talk going about with network security and all, 
and I am not sure if it is relevant to this idea that I have.  I know 
most talks of security are with phishing and what have you.  I thought 
of a hack for TCP that would deter man-in-the-middle / hijacking 
attacks.  I wrote a small thing on it here: 
http://blogbp.com/archives/2005/07/security_throug.php

The only problem we see with it, is the potential for it taking time to 
come up with (int)1 to (int)1 equations.  So if there is a better reason 
on why this has never been done I would love to know.  I am not the best 
at TCP Protocol programming, and don't really understand what happens at 
that level. 

Thanks,
--
David Walker
Computer Science House
azrail at csh.rit.edu