if anyone finds an encryption library as an alternative to PolarSSL which is not GPL licensed, I would be more than willing to re-license the whole code as MIT/X11.
libtomcrypt is public domain (and we're in the process of releasing LTN12 bindings to it under Eclipse public license; it's under intellectual property review as we speak). I don't know whether it offers all the codecs you're interested in.
The other option is to create a "light-weight" compression library consisting only of bzip2 (BSD-like), zlib (own BSD-like license) and liblzma (public domain), which could then be licensed as MIT.
it would makes sense: I think many people are interested in compression without encryption (and maybe the other way around, although it isn't as obvious). We'd certainly love to have ltn12 compression codecs under a commercial-friendly license--actually, if we don't find any, we'll eventually have to write it ourselves. Beyond licensing issues, I think small and focused libraries fit Lua's philosophy better, even if such modular code is harder to write and ship.