diff --git a/Crypto/Cipher/ChaCha.hs b/Crypto/Cipher/ChaCha.hs
index a45f6f7..8dab24b 100644
--- a/Crypto/Cipher/ChaCha.hs
+++ b/Crypto/Cipher/ChaCha.hs
@@ -90,7 +90,7 @@ combine prev@(State nbRounds prevSt prevOut) src
         -- we have enough byte in the previous buffer to complete the query
         -- without having to generate any extra bytes
         let (b1,b2) = BS.splitAt outputLen prevOut
-         in (BS.pack $ BS.zipWith xor b1 src, State nbRounds prevSt b2)
+         in (B.xor b1 src, State nbRounds prevSt b2)
     | otherwise = unsafeDoIO $ do
         -- adjusted len is the number of bytes lefts to generate after
         -- copying from the previous buffer.
@@ -106,14 +106,13 @@ combine prev@(State nbRounds prevSt prevOut) src
                     loopXor dstPtr srcPtr prevPtr prevBufLen
 
                 -- then create a new mutable copy of state
-                st <- B.copy prevSt (\_ -> return ())
-                withByteArray st $ \stPtr ->
+                B.copy prevSt $ \stPtr ->
                     ccryptonite_chacha_combine nbRounds
                                                (dstPtr `plusPtr` prevBufLen)
                                                (castPtr stPtr)
                                                (srcPtr `plusPtr` prevBufLen)
                                                (fromIntegral newBytesToGenerate)
-                return st
+
         -- return combined byte
         return ( BS.PS fptr 0 outputLen
                , State nbRounds newSt (if roundedAlready then BS.empty else BS.PS fptr outputLen nextBufLen))
diff --git a/Crypto/Cipher/RC4.hs b/Crypto/Cipher/RC4.hs
index 0c1ea4d..8971783 100644
--- a/Crypto/Cipher/RC4.hs
+++ b/Crypto/Cipher/RC4.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE ForeignFunctionInterface #-}
 -- |
 -- Module      : Crypto.Cipher.RC4
 -- License     : BSD-style
@@ -13,6 +12,8 @@
 --
 -- Reorganized and simplified to have an opaque context.
 --
+{-# LANGUAGE ForeignFunctionInterface #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
 module Crypto.Cipher.RC4
     ( initialize
     , combine
@@ -20,19 +21,16 @@ module Crypto.Cipher.RC4
     , State
     ) where
 
-import Data.Word
-import Data.Byteable
-import Data.SecureMem
-import Foreign.Ptr
-import Foreign.ForeignPtr
-import Data.ByteString (ByteString)
-import qualified Data.ByteString as B
-import qualified Data.ByteString.Internal as B
+import           Data.Word
+import           Foreign.Ptr
+import           Crypto.Internal.ByteArray (SecureBytes, ByteArray, ByteArrayAccess)
+import qualified Crypto.Internal.ByteArray as B
 
 import Crypto.Internal.Compat
 
 -- | The encryption state for RC4
-newtype State = State SecureMem
+newtype State = State SecureBytes
+    deriving (ByteArrayAccess)
 
 -- | C Call for initializing the encryptor
 foreign import ccall unsafe "cryptonite_rc4.h cryptonite_rc4_init"
@@ -52,29 +50,29 @@ foreign import ccall unsafe "cryptonite_rc4.h cryptonite_rc4_combine"
 --
 -- seed the context with an initial key. the key size need to be
 -- adequate otherwise security takes a hit.
-initialize :: Byteable key
+initialize :: ByteArrayAccess key
            => key   -- ^ The key
            -> State -- ^ The RC4 context with the key mixed in
 initialize key = unsafeDoIO $ do
-    st <- createSecureMem 264 $ \stPtr ->
-        withBytePtr key $ \keyPtr -> c_rc4_init keyPtr (fromIntegral $ byteableLength key) (castPtr stPtr)
+    st <- B.alloc 264 $ \stPtr ->
+        B.withByteArray key $ \keyPtr -> c_rc4_init keyPtr (fromIntegral $ B.length key) (castPtr stPtr)
     return $ State st
 
 -- | generate the next len bytes of the rc4 stream without combining
 -- it to anything.
-generate :: State -> Int -> (State, ByteString)
-generate ctx len = combine ctx (B.replicate len 0)
+generate :: ByteArray ba => State -> Int -> (State, ba)
+generate ctx len = combine ctx (B.zero len)
 
 -- | RC4 xor combination of the rc4 stream with an input
-combine :: State               -- ^ rc4 context
-        -> ByteString          -- ^ input
-        -> (State, ByteString) -- ^ new rc4 context, and the output
-combine (State prevSt) clearText = unsafeDoIO $ do
-    outfptr <- B.mallocByteString len
-    st      <- secureMemCopy prevSt
-    withSecureMemPtr st $ \stPtr ->
-        withForeignPtr outfptr $ \outptr ->
-        withBytePtr clearText $ \clearPtr ->
-            c_rc4_combine (castPtr stPtr) clearPtr (fromIntegral len) outptr
-    return $! (State st, B.PS outfptr 0 len)
+combine :: ByteArray ba
+        => State               -- ^ rc4 context
+        -> ba                  -- ^ input
+        -> (State, ba)         -- ^ new rc4 context, and the output
+combine (State prevSt) clearText = unsafeDoIO $
+    B.allocRet len            $ \outptr ->
+    B.withByteArray clearText $ \clearPtr -> do
+        st <- B.copy prevSt $ \stPtr ->
+                c_rc4_combine (castPtr stPtr) clearPtr (fromIntegral len) outptr
+        return $! State st
+    --return $! (State st, B.PS outfptr 0 len)
   where len = B.length clearText
diff --git a/Crypto/Cipher/Types/Base.hs b/Crypto/Cipher/Types/Base.hs
index 09861d0..d9bb16b 100644
--- a/Crypto/Cipher/Types/Base.hs
+++ b/Crypto/Cipher/Types/Base.hs
@@ -20,7 +20,7 @@ module Crypto.Cipher.Types.Base
 import           Data.Word
 import           Data.ByteString (ByteString)
 
-import           Crypto.Internal.ByteArray (ByteArrayAccess, ByteArray, SecureBytes, withByteArray)
+import           Crypto.Internal.ByteArray (ByteArrayAccess, ByteArray)
 import qualified Crypto.Internal.ByteArray as B
 import           Crypto.Error
 
diff --git a/Crypto/Cipher/Types/Block.hs b/Crypto/Cipher/Types/Block.hs
index e56457b..a0d584c 100644
--- a/Crypto/Cipher/Types/Block.hs
+++ b/Crypto/Cipher/Types/Block.hs
@@ -36,7 +36,6 @@ module Crypto.Cipher.Types.Block
     --, cfb8Decrypt
     ) where
 
-import           Data.Byteable
 import           Data.Word
 import           Crypto.Error
 import           Crypto.Cipher.Types.Base
@@ -146,12 +145,12 @@ class BlockCipher cipher => BlockCipher128 cipher where
     xtsDecrypt = xtsDecryptGeneric
 
 -- | Create an IV for a specified block cipher
-makeIV :: (Byteable b, BlockCipher c) => b -> Maybe (IV c)
+makeIV :: (ByteArrayAccess b, BlockCipher c) => b -> Maybe (IV c)
 makeIV b = toIV undefined
   where toIV :: BlockCipher c => c -> Maybe (IV c)
         toIV cipher
-          | byteableLength b == sz = Just (IV $ toBytes b)
-          | otherwise              = Nothing
+          | B.length b == sz = Just $ IV (B.convert b :: Bytes)
+          | otherwise        = Nothing
           where sz = blockSize cipher
 
 -- | Create an IV that is effectively representing the number 0
diff --git a/Crypto/Data/AFIS.hs b/Crypto/Data/AFIS.hs
index 8f173ca..2b06bef 100644
--- a/Crypto/Data/AFIS.hs
+++ b/Crypto/Data/AFIS.hs
@@ -21,6 +21,8 @@ module Crypto.Data.AFIS
 import Crypto.Hash
 import Crypto.Random.Types
 import Crypto.Internal.Memory (Bytes)
+import Crypto.Internal.Bytes (bufSet, bufCopy)
+import Crypto.Internal.Compat
 import Crypto.Internal.ByteArray (withByteArray)
 import Control.Monad (forM_, foldM)
 import Data.Byteable
@@ -29,11 +31,10 @@ import Data.Word
 import Data.Bits
 import Foreign.Storable
 import Foreign.Ptr
-import Foreign.ForeignPtr (withForeignPtr, newForeignPtr_)
-import qualified Data.ByteString as B
+import Foreign.ForeignPtr (newForeignPtr_)
 import qualified Data.ByteString.Internal as B
 
-import System.IO.Unsafe (unsafePerformIO)
+import qualified Crypto.Internal.ByteArray as B
 
 -- | Split data to diffused data, using a random generator and
 -- an hash algorithm.
@@ -62,15 +63,14 @@ split :: (HashAlgorithm a, DRG rng)
 {-# NOINLINE split #-}
 split hashF rng expandTimes src
     | expandTimes <= 1 = error "invalid expandTimes value"
-    | otherwise        = unsafePerformIO $ do
-        fptr <- B.mallocByteString diffusedLen
-        rng' <- withForeignPtr fptr runOp
-        return (B.fromForeignPtr fptr 0 diffusedLen, rng')
+    | otherwise        = unsafeDoIO $ do
+        (rng', bs) <- B.allocRet diffusedLen runOp
+        return (bs, rng')
   where diffusedLen = blockSize * expandTimes
         blockSize   = B.length src
         runOp dstPtr = do
             let lastBlock = dstPtr `plusPtr` (blockSize * (expandTimes-1))
-            _ <- B.memset lastBlock 0 (fromIntegral blockSize)
+            bufSet lastBlock 0 blockSize
             let randomBlockPtrs = map (plusPtr dstPtr . (*) blockSize) [0..(expandTimes-2)]
             rng' <- foldM fillRandomBlock rng randomBlockPtrs
             mapM_ (addRandomBlock lastBlock) randomBlockPtrs
@@ -81,7 +81,7 @@ split hashF rng expandTimes src
             diffuse hashF lastBlock blockSize
         fillRandomBlock g blockPtr = do
             let (rand :: Bytes, g') = randomBytesGenerate blockSize g
-            withByteArray rand $ \randPtr -> B.memcpy blockPtr randPtr (fromIntegral blockSize)
+            withByteArray rand $ \randPtr -> bufCopy blockPtr randPtr (fromIntegral blockSize)
             return g'
 
 -- | Merge previously diffused data back to the original data.
@@ -94,9 +94,9 @@ merge :: HashAlgorithm a
 merge hashF expandTimes bs
     | r /= 0            = error "diffused data not a multiple of expandTimes"
     | originalSize <= 0 = error "diffused data null"
-    | otherwise         = unsafePerformIO $ B.create originalSize $ \dstPtr ->
-        withBytePtr bs $ \srcPtr -> do
-            _ <- B.memset dstPtr 0 (fromIntegral originalSize)
+    | otherwise         = B.allocAndFreeze originalSize $ \dstPtr ->
+        B.withByteArray bs $ \srcPtr -> do
+            bufSet dstPtr 0 originalSize
             forM_ [0..(expandTimes-2)] $ \i -> do
                 xorMem (srcPtr `plusPtr` (i * originalSize)) dstPtr originalSize
                 diffuse hashF dstPtr originalSize
@@ -126,10 +126,10 @@ diffuse :: HashAlgorithm a
 diffuse hashF src sz = loop src 0
   where (full,pad) = sz `quotRem` digestSize 
         loop s i | i < full = do h <- hashBlock i `fmap` byteStringOfPtr s digestSize
-                                 withBytePtr h $ \hPtr -> B.memcpy s hPtr (fromIntegral digestSize)
+                                 B.withByteArray h $ \hPtr -> bufCopy s hPtr digestSize
                                  loop (s `plusPtr` digestSize) (i+1)
                  | pad /= 0 = do h <- hashBlock i `fmap` byteStringOfPtr s pad
-                                 withBytePtr h $ \hPtr -> B.memcpy s hPtr (fromIntegral pad)
+                                 B.withByteArray h $ \hPtr -> bufCopy s hPtr pad
                                  return ()
                  | otherwise = return ()
 
@@ -139,12 +139,12 @@ diffuse hashF src sz = loop src 0
         byteStringOfPtr ptr digestSz = newForeignPtr_ ptr >>= \fptr -> return $ B.fromForeignPtr fptr 0 digestSz
 
         hashBlock n b =
-            toBytes $ hashF $ B.unsafeCreate (B.length b+4) $ \ptr -> do
+            toBytes $ hashF $ B.allocAndFreeze (B.length b+4) $ \ptr -> do
                 poke ptr               (f8 (n `shiftR` 24))
                 poke (ptr `plusPtr` 1) (f8 (n `shiftR` 16))
                 poke (ptr `plusPtr` 2) (f8 (n `shiftR` 8))
                 poke (ptr `plusPtr` 3) (f8 n)
                 --putWord32BE (fromIntegral n) >> putBytes src)
-                withBytePtr b $ \srcPtr -> B.memcpy (ptr `plusPtr` 4) srcPtr (fromIntegral $ B.length b)
+                withByteArray b $ \srcPtr -> bufCopy (ptr `plusPtr` 4) srcPtr (B.length b)
           where f8 :: Int -> Word8
                 f8 = fromIntegral
diff --git a/Crypto/Internal/ByteArray.hs b/Crypto/Internal/ByteArray.hs
index 9c49384..606dfc0 100644
--- a/Crypto/Internal/ByteArray.hs
+++ b/Crypto/Internal/ByteArray.hs
@@ -18,12 +18,14 @@ module Crypto.Internal.ByteArray
     -- * Inhabitants
     , Bytes
     , SecureBytes
+    , MemView(..)
     -- * methods
     , alloc
     , allocAndFreeze
     , empty
     , zero
     , copy
+    , take
     , convert
     , copyRet
     , copyAndFreeze
@@ -57,6 +59,12 @@ import qualified Data.ByteString.Internal as B
 
 import Prelude (flip, return, div, (-), ($), (==), (/=), (<=), (>=), Int, Bool(..), IO, otherwise, sum, map, fmap, snd, (.), min)
 
+data MemView = MemView !(Ptr Word8) !Int
+
+instance ByteArrayAccess MemView where
+    length (MemView _ l) = l
+    withByteArray (MemView p _) f = f (castPtr p)
+
 class ByteArrayAccess ba where
     length        :: ba -> Int
     withByteArray :: ba -> (Ptr p -> IO a) -> IO a
@@ -126,6 +134,13 @@ split n bs
             return (b1, b2)
   where len = length bs
 
+take :: ByteArray bs => Int -> bs -> bs
+take n bs =
+    allocAndFreeze m $ \d -> withByteArray bs $ \s -> bufCopy d s m
+  where
+        m   = min len n
+        len = length bs
+
 concat :: ByteArray bs => [bs] -> bs
 concat []    = empty
 concat allBs = allocAndFreeze total (loop allBs)
diff --git a/Crypto/MAC/Poly1305.hs b/Crypto/MAC/Poly1305.hs
index b4e05dc..47d9038 100644
--- a/Crypto/MAC/Poly1305.hs
+++ b/Crypto/MAC/Poly1305.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE ForeignFunctionInterface #-}
 
 -- |
 -- Module      : Crypto.MAC.Poly1305
@@ -9,6 +8,8 @@
 --
 -- Poly1305 implementation
 --
+{-# LANGUAGE ForeignFunctionInterface #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
 module Crypto.MAC.Poly1305
     ( Ctx
     , Auth(..)
@@ -22,27 +23,22 @@ module Crypto.MAC.Poly1305
     , auth
     ) where
 
-import Control.Monad (void)
-import Foreign.Ptr
-import Foreign.C.Types
-import qualified Data.ByteString as B
-import qualified Data.ByteString.Internal as B
-import Data.ByteString (ByteString)
-import Data.Word
-import Data.Byteable
-import System.IO.Unsafe
-import Data.SecureMem
+import           Foreign.Ptr
+import           Foreign.C.Types
+import           Data.Word
+import           Crypto.Internal.ByteArray (ByteArrayAccess, SecureBytes, Bytes)
+import qualified Crypto.Internal.ByteArray as B
 
 -- | Poly1305 Context
-newtype Ctx = Ctx SecureMem
+newtype Ctx = Ctx SecureBytes
+    deriving (ByteArrayAccess)
 
 -- | Poly1305 Auth
-newtype Auth = Auth ByteString
+newtype Auth = Auth Bytes
+    deriving (ByteArrayAccess)
 
 instance Eq Auth where
-    (Auth a1) == (Auth a2) = constEqBytes a1 a2
-instance Byteable Auth where
-    toBytes (Auth b) = b
+    (Auth a1) == (Auth a2) = B.constEq a1 a2
 
 foreign import ccall unsafe "cryptonite_poly1305.h cryptonite_poly1305_init"
     c_poly1305_init :: Ptr Ctx -> Ptr Word8 -> IO ()
@@ -54,55 +50,50 @@ foreign import ccall unsafe "cryptonite_poly1305.h cryptonite_poly1305_finalize"
     c_poly1305_finalize :: Ptr Word8 -> Ptr Ctx -> IO ()
 
 -- | initialize a Poly1305 context
-initialize :: Byteable key
-     => key
-     -> Ctx
+initialize :: ByteArrayAccess key
+           => key
+           -> Ctx
 initialize key
-    | byteableLength key /= 32 = error "Poly1305: key length expected 32 bytes"
-    | otherwise          = Ctx $ unsafePerformIO $ do
-        withBytePtr key $ \keyPtr ->
-            createSecureMem 84 $ \ctxPtr ->
-                c_poly1305_init (castPtr ctxPtr) keyPtr
+    | B.length key /= 32 = error "Poly1305: key length expected 32 bytes"
+    | otherwise          = Ctx $ B.allocAndFreeze 84 $ \ctxPtr ->
+        B.withByteArray key $ \keyPtr ->
+            c_poly1305_init (castPtr ctxPtr) keyPtr
 {-# NOINLINE initialize #-}
 
 -- | update a context with a bytestring
-update :: Ctx -> ByteString -> Ctx
-update (Ctx prevCtx) d = unsafePerformIO $ do
-    ctx <- secureMemCopy prevCtx
-    withSecureMemPtr ctx $ \ctxPtr ->
-        withBytePtr d $ \dataPtr ->
-            c_poly1305_update (castPtr ctxPtr) dataPtr (fromIntegral $ B.length d)
-    return $ Ctx ctx
+update :: ByteArrayAccess ba => Ctx -> ba -> Ctx
+update (Ctx prevCtx) d = Ctx $ B.copyAndFreeze prevCtx $ \ctxPtr ->
+    B.withByteArray d $ \dataPtr ->
+        c_poly1305_update (castPtr ctxPtr) dataPtr (fromIntegral $ B.length d)
 {-# NOINLINE update #-}
 
 -- | updates a context with multiples bytestring
-updates :: Ctx -> [ByteString] -> Ctx
-updates (Ctx prevCtx) d = unsafePerformIO $ do
-    ctx <- secureMemCopy prevCtx
-    withSecureMemPtr ctx (loop d . castPtr)
-    return $ Ctx ctx
+updates :: ByteArrayAccess ba => Ctx -> [ba] -> Ctx
+updates (Ctx prevCtx) d = Ctx $ B.copyAndFreeze prevCtx (loop d)
   where loop []     _      = return ()
         loop (x:xs) ctxPtr = do
-            withBytePtr x $ \dataPtr -> c_poly1305_update ctxPtr dataPtr (fromIntegral $ B.length x)
+            B.withByteArray x $ \dataPtr -> c_poly1305_update ctxPtr dataPtr (fromIntegral $ B.length x)
             loop xs ctxPtr
 {-# NOINLINE updates #-}
 
 -- | finalize the context into a digest bytestring
 finalize :: Ctx -> Auth
-finalize (Ctx prevCtx) = Auth $ B.unsafeCreate 16 $ \dst -> do
-    ctx <- secureMemCopy prevCtx
-    withSecureMemPtr ctx $ \ctxPtr -> c_poly1305_finalize dst (castPtr ctxPtr)
+finalize (Ctx prevCtx) = Auth $ B.allocAndFreeze 16 $ \dst -> do
+    _ <- B.copy prevCtx (\ctxPtr -> c_poly1305_finalize dst (castPtr ctxPtr)) :: IO SecureBytes
+    return ()
 {-# NOINLINE finalize #-}
 
 -- | One-pass authorization creation
-auth :: Byteable key => key -> ByteString -> Auth
+auth :: (ByteArrayAccess key, ByteArrayAccess ba) => key -> ba -> Auth
 auth key d
-    | byteableLength key /= 32 = error "Poly1305: key length expected 32 bytes"
-    | otherwise                = Auth $ B.unsafeCreate 16 $ \dst -> do
-        -- initialize the context
-        void $ createSecureMem 84 $ \ctxPtr -> withBytePtr key $ \keyPtr -> do
-                    c_poly1305_init (castPtr ctxPtr) keyPtr
-                    withBytePtr d $ \dataPtr ->
-                        c_poly1305_update (castPtr ctxPtr) dataPtr (fromIntegral $ B.length d)
-                    -- finalize
-                    c_poly1305_finalize dst (castPtr ctxPtr)
+    | B.length key /= 32 = error "Poly1305: key length expected 32 bytes"
+    | otherwise          = Auth $ B.allocAndFreeze 16 $ \dst -> do
+        _ <- B.alloc 84 (onCtx dst) :: IO SecureBytes
+        return ()
+  where
+        onCtx dst ctxPtr =
+            B.withByteArray key $ \keyPtr -> do
+                c_poly1305_init (castPtr ctxPtr) keyPtr
+                B.withByteArray d $ \dataPtr ->
+                    c_poly1305_update (castPtr ctxPtr) dataPtr (fromIntegral $ B.length d)
+                c_poly1305_finalize dst (castPtr ctxPtr)
diff --git a/Crypto/Random/EntropyPool.hs b/Crypto/Random/EntropyPool.hs
index dc2ccfa..0d55d19 100644
--- a/Crypto/Random/EntropyPool.hs
+++ b/Crypto/Random/EntropyPool.hs
@@ -14,9 +14,8 @@ module Crypto.Random.EntropyPool
 
 import           Control.Concurrent.MVar
 import           Crypto.Random.Entropy.Unsafe
-import           Crypto.Internal.ByteArray (ByteArray)
+import           Crypto.Internal.ByteArray (ByteArray, SecureBytes)
 import qualified Crypto.Internal.ByteArray as B
-import           Data.SecureMem
 import           Data.Word (Word8)
 import           Data.Maybe (catMaybes)
 import           Foreign.Marshal.Utils (copyBytes)
@@ -24,7 +23,7 @@ import           Foreign.Ptr (plusPtr, Ptr)
 
 -- | Pool of Entropy. contains a self mutating pool of entropy,
 -- that is always guarantee to contains data.
-data EntropyPool = EntropyPool [EntropyBackend] (MVar Int) SecureMem
+data EntropyPool = EntropyPool [EntropyBackend] (MVar Int) SecureBytes
 
 -- size of entropy pool by default
 defaultPoolSize :: Int
@@ -35,9 +34,8 @@ defaultPoolSize = 4096
 -- While you can create as many entropy pool as you want, the pool can be shared between multiples RNGs.
 createEntropyPoolWith :: Int -> [EntropyBackend] -> IO EntropyPool
 createEntropyPoolWith poolSize backends = do
-    sm <- allocateSecureMem poolSize
     m  <- newMVar 0
-    withSecureMemPtr sm $ replenish poolSize backends
+    sm <- B.alloc poolSize (replenish poolSize backends)
     return $ EntropyPool backends m sm
 
 -- | Create a new entropy pool with a default size.
@@ -51,10 +49,10 @@ createEntropyPool = do
 -- | Put a chunk of the entropy pool into a buffer
 getEntropyPtr :: EntropyPool -> Int -> Ptr Word8 -> IO ()
 getEntropyPtr (EntropyPool backends posM sm) n outPtr =
-    withSecureMemPtr sm $ \entropyPoolPtr ->
+    B.withByteArray sm $ \entropyPoolPtr ->
         modifyMVar_ posM $ \pos ->
             copyLoop outPtr entropyPoolPtr pos n
-  where poolSize = secureMemGetSize sm
+  where poolSize = B.length sm
         copyLoop d s pos left
             | left == 0 = return pos
             | otherwise = do