I've taken one of the two approaches, and put it in code. It works, but currently only for lower-case letters (and not terribly reliable); I guess I'm doing a stupid mistake somewhere, and my code is much more complicated than it needs to be. Anyway, here's the code:

$ perl banner.pl | perl unbanner.pl 
st anotherl hacke
[download]

I'll try to debug and improve it a bit, pending sufficient round tuits.

Thanks for the challenge, always fun to attack them!