diff --git a/clientsession.cabal b/clientsession.cabal
--- a/clientsession.cabal
+++ b/clientsession.cabal
@@ -1,5 +1,5 @@
 name:            clientsession
-version:         0.7.5
+version:         0.8.0
 license:         BSD3
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>, Felipe Lessa <felipe.lessa@gmail.com>
@@ -41,11 +41,12 @@
     build-depends:   base                >=4           && < 5
                    , bytestring          >= 0.9        && < 0.10
                    , cryptocipher        >= 0.2.5
-                   , hspec               >= 0.6        && < 0.10
+                   , hspec               >= 1.2        && < 1.3
                    , QuickCheck          >= 2          && < 3
                    , HUnit
                    , transformers
                    , containers
+                   , cereal              >= 0.3        && < 0.4
                    -- finally, our own package
                    , clientsession
     ghc-options:     -Wall
diff --git a/src/Web/ClientSession.hs b/src/Web/ClientSession.hs
--- a/src/Web/ClientSession.hs
+++ b/src/Web/ClientSession.hs
@@ -38,7 +38,7 @@
 ---------------------------------------------------------
 module Web.ClientSession
     ( -- * Automatic key generation
-      Key(..)
+      Key
     , IV
     , randomIV
     , mkIV
@@ -46,6 +46,7 @@
     , defaultKeyFile
     , getDefaultKey
     , initKey
+    , randomKey
       -- * Actual encryption/decryption
     , encrypt
     , encryptIO
@@ -57,6 +58,7 @@
 import qualified Data.IORef as I
 import System.IO.Unsafe (unsafePerformIO)
 import Control.Concurrent (forkIO)
+import Control.Applicative ((<$>))
 
 -- from directory
 import System.Directory (doesFileExist)
@@ -66,7 +68,7 @@
 import qualified Data.ByteString.Base64 as B
 
 -- from cereal
-import Data.Serialize (encode, decode)
+import Data.Serialize (encode, decode, Serialize (put, get), getBytes, putByteString)
 
 -- from tagged
 import Data.Tagged (Tagged, untag)
@@ -102,8 +104,16 @@
                  -- ^ Skein-MAC key.  Instead of storing the key
                  -- data, we store a partially applied function
                  -- for calculating the MAC (see 'skeinMAC'').
+               , keyRaw :: S.ByteString
                }
 
+instance Eq Key where
+    Key a _ b == Key x _ y = encode a == encode x && b == y
+
+instance Serialize Key where
+    put = putByteString . keyRaw
+    get = either error id . initKey <$> getBytes 96
+
 -- | Dummy 'Show' instance.
 instance Show Key where
     show _ = "<Web.ClientSession.Key>"
@@ -168,7 +178,9 @@
 initKey bs = case buildKey preAesKey of
                Nothing -> Left $ "Web.ClientSession.initKey: unknown error with buildKey."
                Just k  -> Right $ Key { aesKey = k
-                                      , macKey = skeinMAC' preMacKey }
+                                      , macKey = skeinMAC' preMacKey
+                                      , keyRaw = bs
+                                      }
     where
       (preMacKey, preAesKey) = S.splitAt 64 bs
 
diff --git a/tests/runtests.hs b/tests/runtests.hs
--- a/tests/runtests.hs
+++ b/tests/runtests.hs
@@ -19,14 +19,17 @@
 import Control.Monad.Trans.Class (lift)
 import Control.Monad (replicateM_)
 
+import Data.Serialize (encode, decode)
+
 main :: IO ()
-main = hspecX $ describe "client session" $ do
+main = hspec $ describe "client session" $ do
     it "encrypt/decrypt success" $ property propEncDec
     it "encrypt/decrypt failure" $ property propEncDecFailure
     it "AES encrypt/decrypt success" $ property propAES
     it "AES encryption changes bs" $ property propAESChanges
     it "specific values" caseSpecific
     it "randomIV is really random" caseRandomIV
+    it "serialize instance" $ property propSerialize
 
 propEncDec :: S.ByteString -> Bool
 propEncDec bs = unsafePerformIO $ do
@@ -67,6 +70,9 @@
         lift $ assertBool "No duplicated keys" (not $ val `Set.member` set)
         put $ Set.insert val set
 
+propSerialize :: MyKey -> Bool
+propSerialize (MyKey key) = Right key == decode (encode key)
+
 instance Arbitrary S.ByteString where
     arbitrary = S.pack `fmap` arbitrary
 
@@ -78,7 +84,7 @@
         either error (return . MyKey) $ initKey $ S.pack ws
 
 instance Show MyKey where
-    show _ = "<Key>"
+    show (MyKey key) = "MyKey:" ++ show (encode key)
 
 newtype MyIV = MyIV IV