diff --git a/Crypto/Cipher/Types/AEAD.hs b/Crypto/Cipher/Types/AEAD.hs
index a6c41ad..2759dfc 100644
--- a/Crypto/Cipher/Types/AEAD.hs
+++ b/Crypto/Cipher/Types/AEAD.hs
@@ -7,53 +7,58 @@
 --
 -- AEAD cipher basic types
 --
+{-# LANGUAGE ExistentialQuantification #-}
+{-# LANGUAGE Rank2Types #-}
 module Crypto.Cipher.Types.AEAD where
 
-import Data.ByteString (ByteString)
-import qualified Data.ByteString as B
 import Crypto.Cipher.Types.Base
-import Crypto.Cipher.Types.Block
 import Crypto.Internal.ByteArray
+import Crypto.Internal.Imports
 
--- | Append associated data into the AEAD state
-aeadAppendHeader :: BlockCipher a => AEAD a -> ByteString -> AEAD a
-aeadAppendHeader (AEAD cipher (AEADState state)) bs =
-    AEAD cipher $ AEADState (aeadStateAppendHeader cipher state bs)
+data AEADModeImpl st = AEADModeImpl
+    { aeadImplAppendHeader :: forall ba . ByteArrayAccess ba => st -> ba -> st
+    , aeadImplEncrypt      :: forall ba . ByteArray ba => st -> ba -> (ba, st)
+    , aeadImplDecrypt      :: forall ba . ByteArray ba => st -> ba -> (ba, st)
+    , aeadImplFinalize     :: st -> Int -> AuthTag
+    }
 
--- | Encrypt input and append into the AEAD state
-aeadEncrypt :: BlockCipher a => AEAD a -> ByteString -> (ByteString, AEAD a)
-aeadEncrypt (AEAD cipher (AEADState state)) input = (output, AEAD cipher (AEADState nst))
-  where (output, nst) = aeadStateEncrypt cipher state input
+-- | Authenticated Encryption with Associated Data algorithms
+data AEAD cipher = forall st . AEAD
+    { aeadModeImpl :: AEADModeImpl st
+    , aeadState    :: st
+    }
 
--- | Decrypt input and append into the AEAD state
-aeadDecrypt :: BlockCipher a => AEAD a -> ByteString -> (ByteString, AEAD a)
-aeadDecrypt (AEAD cipher (AEADState state)) input = (output, AEAD cipher (AEADState nst))
-  where (output, nst) = aeadStateDecrypt cipher state input
+aeadAppendHeader :: ByteArrayAccess aad => AEAD cipher -> aad -> AEAD cipher
+aeadAppendHeader (AEAD impl st) aad = AEAD impl $ (aeadImplAppendHeader impl) st aad
 
--- | Finalize the AEAD state and create an authentification tag
-aeadFinalize :: BlockCipher a => AEAD a -> Int -> AuthTag
-aeadFinalize (AEAD cipher (AEADState state)) len =
-    aeadStateFinalize cipher state len
+aeadEncrypt :: ByteArray ba => AEAD cipher -> ba -> (ba, AEAD cipher)
+aeadEncrypt (AEAD impl st) ba = second (AEAD impl) $ (aeadImplEncrypt impl) st ba
+
+aeadDecrypt :: ByteArray ba => AEAD cipher -> ba -> (ba, AEAD cipher)
+aeadDecrypt (AEAD impl st) ba = second (AEAD impl) $ (aeadImplDecrypt impl) st ba
+
+aeadFinalize :: AEAD cipher -> Int -> AuthTag
+aeadFinalize (AEAD impl st) n = (aeadImplFinalize impl) st n
 
 -- | Simple AEAD encryption
-aeadSimpleEncrypt :: BlockCipher a
+aeadSimpleEncrypt :: (ByteArrayAccess aad, ByteArray ba)
                   => AEAD a        -- ^ A new AEAD Context
-                  -> B.ByteString  -- ^ Optional Authentified Header
-                  -> B.ByteString  -- ^ Optional Plaintext
+                  -> aad           -- ^ Optional Authentified Header
+                  -> ba            -- ^ Optional Plaintext
                   -> Int           -- ^ Tag length
-                  -> (AuthTag, B.ByteString) -- ^ Authentification tag and ciphertext
+                  -> (AuthTag, ba) -- ^ Authentification tag and ciphertext
 aeadSimpleEncrypt aeadIni header input taglen = (tag, output)
   where aead                = aeadAppendHeader aeadIni header
         (output, aeadFinal) = aeadEncrypt aead input
         tag                 = aeadFinalize aeadFinal taglen
 
 -- | Simple AEAD decryption
-aeadSimpleDecrypt :: BlockCipher a
+aeadSimpleDecrypt :: (ByteArrayAccess aad, ByteArray ba)
                   => AEAD a        -- ^ A new AEAD Context
-                  -> B.ByteString  -- ^ Optional Authentified Header
-                  -> B.ByteString  -- ^ Optional Plaintext
+                  -> aad           -- ^ Optional Authentified Header
+                  -> ba            -- ^ Optional Plaintext
                   -> AuthTag       -- ^ Tag length
-                  -> Maybe B.ByteString -- ^ Plaintext
+                  -> Maybe ba      -- ^ Plaintext
 aeadSimpleDecrypt aeadIni header input authTag
     | tag == authTag = Just output
     | otherwise      = Nothing
diff --git a/Crypto/Cipher/Types/Block.hs b/Crypto/Cipher/Types/Block.hs
index 8a8f060..24dad45 100644
--- a/Crypto/Cipher/Types/Block.hs
+++ b/Crypto/Cipher/Types/Block.hs
@@ -24,8 +24,12 @@ module Crypto.Cipher.Types.Block
     , XTS
     -- * AEAD
     , AEAD(..)
-    , AEADState(..)
+    -- , AEADState(..)
     , AEADModeImpl(..)
+    , aeadAppendHeader
+    , aeadEncrypt
+    , aeadDecrypt
+    , aeadFinalize
     -- * CFB 8 bits
     --, cfb8Encrypt
     --, cfb8Decrypt
@@ -35,8 +39,10 @@ import Data.ByteString (ByteString)
 import qualified Data.ByteString as B
 import Data.Byteable
 import Data.Word
+import Crypto.Error
 import Crypto.Cipher.Types.Base
 import Crypto.Cipher.Types.GF
+import Crypto.Cipher.Types.AEAD
 import Crypto.Cipher.Types.Utils
 
 import Crypto.Internal.ByteArray
@@ -110,8 +116,8 @@ class Cipher cipher => BlockCipher cipher where
     -- | Initialize a new AEAD State
     --
     -- When Nothing is returns, it means the mode is not handled.
-    aeadInit :: Byteable iv => AEADMode -> cipher -> iv -> Maybe (AEAD cipher)
-    aeadInit _ _ _ = Nothing
+    aeadInit :: ByteArrayAccess iv => AEADMode -> cipher -> iv -> CryptoFailable (AEAD cipher)
+    aeadInit _ _ _ = CryptoFailed CryptoError_AEADModeNotSupported
 
 -- | class of block cipher with a 128 bits block size
 class BlockCipher cipher => BlockCipher128 cipher where
@@ -139,19 +145,6 @@ class BlockCipher cipher => BlockCipher128 cipher where
                -> ba               -- ^ Plaintext
     xtsDecrypt = xtsDecryptGeneric
 
--- | Authenticated Encryption with Associated Data algorithms
-data AEAD cipher = AEAD cipher (AEADState cipher)
-
--- | Wrapper for any AEADState
-data AEADState cipher = forall st . AEADModeImpl cipher st => AEADState st
-
--- | Class of AEAD Mode implementation
-class BlockCipher cipher => AEADModeImpl cipher state where
-    aeadStateAppendHeader :: cipher -> state -> ByteString -> state
-    aeadStateEncrypt      :: cipher -> state -> ByteString -> (ByteString, state)
-    aeadStateDecrypt      :: cipher -> state -> ByteString -> (ByteString, state)
-    aeadStateFinalize     :: cipher -> state -> Int -> AuthTag
-
 -- | Create an IV for a specified block cipher
 makeIV :: (Byteable b, BlockCipher c) => b -> Maybe (IV c)
 makeIV b = toIV undefined
diff --git a/Crypto/Error/Types.hs b/Crypto/Error/Types.hs
index 008bd21..368f5ef 100644
--- a/Crypto/Error/Types.hs
+++ b/Crypto/Error/Types.hs
@@ -28,6 +28,7 @@ data CryptoError =
     -- symmetric cipher errors
       CryptoError_KeySizeInvalid
     | CryptoError_IvSizeInvalid
+    | CryptoError_AEADModeNotSupported
     deriving (Show,Eq,Enum,Data,Typeable)
 
 instance E.Exception CryptoError
diff --git a/tests/BlockCipher.hs b/tests/BlockCipher.hs
index f52f2c7..5ea615a 100644
--- a/tests/BlockCipher.hs
+++ b/tests/BlockCipher.hs
@@ -57,7 +57,7 @@ data KAT_CFB = KAT_CFB
 data KAT_CTR = KAT_CTR
     { ctrKey        :: ByteString -- ^ Key
     , ctrIV         :: ByteString -- ^ IV (usually represented as a 128 bits integer)
-    , ctrPlaintext  :: ByteString -- ^ Plaintext 
+    , ctrPlaintext  :: ByteString -- ^ Plaintext
     , ctrCiphertext :: ByteString -- ^ Ciphertext
     } deriving (Show,Eq)
 
@@ -398,14 +398,16 @@ testBlockCipherAEAD cipher =
         toTests _ = testProperty_AEAD
         testProperty_AEAD mode (AEADUnit key testIV (unPlaintext -> aad) (unPlaintext -> plaintext)) = withCtx key $ \ctx ->
             case aeadInit mode ctx testIV of
-                Just iniAead ->
+                CryptoPassed iniAead ->
                     let aead           = aeadAppendHeader iniAead aad
                         (eText, aeadE) = aeadEncrypt aead plaintext
                         (dText, aeadD) = aeadDecrypt aead eText
                         eTag           = aeadFinalize aeadE (blockSize ctx)
                         dTag           = aeadFinalize aeadD (blockSize ctx)
                      in (plaintext `assertEq` dText) && (eTag `byteArrayEq` dTag)
-                Nothing -> True
+                CryptoFailed err
+                    | err == CryptoError_AEADModeNotSupported -> True
+                    | otherwise                               -> error ("testProperty_AEAD: " ++ show err)
 
 withCtx :: Cipher c => Key c -> (c -> a) -> a
 withCtx (Key key) f =