newCipher :: ByteString -> ByteString -> IO Cipher
newCipher key iv = BS.useAsCStringLen key $ \(ckey, _) ->
    BS.useAsCStringLen iv $ \(civ, _) ->
        c_newCipher ckey civ
newCipher :: ByteString -> ByteString -> IO Cipher
newCipher key iv = BS.useAsCStringLen key $ \(ckey, _) ->
    BS.useAsCStringLen iv $ \(civ, _) ->
        c_newCipher ckey civ
newCipher key iv = BS.useAsCStringLen key $ \(ckey, _) ->
    BS.useAsCStringLen iv $ \(civ, _) ->
        c_newCipher ckey civ