Not quite understanding, provide an example please?
For example, you input a bunch of characters into a GUI or something and that becomes your seed. When you send any message to the server, it alters your text according to the seed you have on.
More examples (Encoding can be done in a different way, this is just an example):
Encoded chat:
(Seed: orange): al katht
(Seed: doge): lk altht
What clients with seed orange see:
hi there
it hiere
What clients with seed doge see:
th itere
hi there