diff --git a/Crypto/Threefish/Skein/Internal.hs b/Crypto/Threefish/Skein/Internal.hs
new file mode 100644
--- /dev/null
+++ b/Crypto/Threefish/Skein/Internal.hs
@@ -0,0 +1,30 @@
+{-# LANGUAGE ForeignFunctionInterface #-}
+-- | Skein FFI internals.
+module Crypto.Threefish.Skein.Internal where
+import Foreign.ForeignPtr
+import Foreign.Ptr
+import Data.Word
+       
+newtype Skein256Ctx = Skein256Ctx (ForeignPtr Word64)
+
+foreign import ccall unsafe skein256_init
+  :: Ptr Word64 -- ^ Skein 256 context to initialize.
+  -> Ptr Word64 -- ^ Desired key or nullPtr.
+  -> Word64     -- ^ Output size in bits.
+  -> IO ()
+
+foreign import ccall unsafe skein256_update
+  :: Ptr Word64 -- ^ Skein 256 context.
+  -> Int        -- ^ First/last update? First starts a new tweak.
+                --  (First bit indicates first, second bit indicates last.)
+  -> Int        -- ^ Type of block, as given by type2int.
+  -> Word64     -- ^ Length of block. Must be multiple of 32 except for last.
+  -> Ptr Word64 -- ^ Pointer to update data.
+  -> IO ()
+
+foreign import ccall unsafe skein256_output
+  :: Ptr Word64 -- ^ Skein 256 context.
+  -> Int        -- ^ First output block to get.
+  -> Int        -- ^ Last output block to get.
+  -> Ptr Word64 -- ^ Pointer to store output data in.
+  -> IO ()
diff --git a/threefish.cabal b/threefish.cabal
--- a/threefish.cabal
+++ b/threefish.cabal
@@ -1,5 +1,5 @@
 name:                threefish
-version:             0.2.1
+version:             0.2.2
 synopsis:            The Threefish block cipher and the Skein hash function for Haskell.
 description:         Implements 256 and 512 bit variants of Threefish and Skein. Skein is usable as a "normal" hash function as well as in Skein-MAC, as a cryptographically secure PRNG, as a stream cipher and as a key derivation function, all implemented according to the specifications of the Skein 1.3 paper.
 homepage:            http://github.com/valderman/threefish
@@ -23,6 +23,7 @@
     Crypto.Threefish.Authenticated,
     Crypto.Threefish.Random,
     Crypto.Threefish.Skein,
+    Crypto.Threefish.Skein.Internal,
     Crypto.Threefish.Skein.KDF,
     Crypto.Threefish.Skein.StreamCipher
   other-modules: