a) not a module. (or atleast a "hackable" module back down to pure perl)
b) mostly obfuscation. Less than pgp, but more than rot13.
c) speed.
d) no embedded c.
Alternatively, you could uuencode it or something ( [search.cpan.org] )
Or compress it with [search.cpan.org]
You might as well actually use some kind of encryption, though, if you go to that level. You can do some kinds really fast. see [search.cpan.org] for some examples.
Hope it helps