[Haskell-cafe] Haskell AES

[tsuraan]

I'd like to use AES in a haskell program that I'm writing.  I've come
across three libraries in hackage that do AES: the library named AES,
the Crypto library, and the SimpleAES library.  The library named AES
says in its documentation for the "crypt" function that it is not
thread-safe.  What exactly does this mean in haskell?  Does it mean
that if you have separate AESCtx instances in different forkIO
"threads", that things will break?  Or does it just mean that using
the same AESCtx in multiple forkIO threads is a bad idea?

I'm asking about that one comment because it looks like SimpleAES is
probably a wrapper around AES, and the Crypto library also says it
uses a library named AES, although one by an author not listed in the
hackage AES library entry.

Can anybody shed some light on the state of AES encryption in haskell?
What is the preferred library, especially for us in a program that has
many forkIO'd "threads"?