diff --git a/cryptoids/src/Data/CryptoID/Poly.hs b/cryptoids/src/Data/CryptoID/Poly.hs
index 5ce359f..9b23ff3 100644
--- a/cryptoids/src/Data/CryptoID/Poly.hs
+++ b/cryptoids/src/Data/CryptoID/Poly.hs
@@ -34,7 +34,6 @@ import qualified Data.ByteString as ByteString
 import qualified Data.ByteString.Char8 as ByteString.Char
 
 import qualified Data.ByteString.Lazy as Lazy (ByteString)
-import qualified Data.ByteString.Lazy as Lazy.ByteString
 
 import Data.List (sortOn)
 import Data.Ord (Down(..))
@@ -142,6 +141,13 @@ genKey = CryptoIDKey <$> liftIO (getEntropy keySize)
       | KeySizeEnum ns <- keySize' = maximum ns
       | KeySizeRange _ max <- keySize' = max
   
+  
+-- | @pad err size src@ appends null bytes to @src@ until it has length that is
+--   a multiple of @size@.
+pad :: ByteArrayAccess a => Int -> a -> ByteString
+pad n (ByteArray.unpack -> src) = ByteString.pack $ src ++ replicate (l `mod` n) 0
+  where
+    l = length src
 
 -- | Use 'CryptoHash' to generate a 'Digest' of the Symbol passed as proxy type
 namespace' :: forall proxy namespace m.
@@ -159,18 +165,18 @@ cryptoFailable :: MonadError CryptoIDError m => CryptoFailable a -> m a
 cryptoFailable = either (throwError . AlgorithmError) return . eitherCryptoError
 
 -- | Encrypt an arbitrary serializable value
-encrypt :: forall a m namespace.
+encrypt :: forall m namespace.
            ( KnownSymbol namespace
            , MonadError CryptoIDError m
            ) => CryptoIDKey -> ByteString -> m (CryptoID namespace ByteString)
 encrypt (keyMaterial -> key) plaintext = do
   cipher <- cryptoFailable (cipherInit key :: CryptoFailable CryptoCipher)
   namespace <- namespace' (Proxy :: Proxy namespace)
-  return . CryptoID $ cbcEncrypt cipher namespace plaintext
+  return . CryptoID . cbcEncrypt cipher namespace $ pad (blockSize cipher) plaintext
 
 
 -- | Decrypt an arbitrary serializable value
-decrypt :: forall a m namespace.
+decrypt :: forall m namespace.
            ( KnownSymbol namespace
            , MonadError CryptoIDError m
            ) => CryptoIDKey -> CryptoID namespace ByteString -> m ByteString
diff --git a/uuid-crypto/src/Data/UUID/Cryptographic.hs b/uuid-crypto/src/Data/UUID/Cryptographic.hs
index b31d0f8..2356bf1 100644
--- a/uuid-crypto/src/Data/UUID/Cryptographic.hs
+++ b/uuid-crypto/src/Data/UUID/Cryptographic.hs
@@ -43,8 +43,6 @@ import Control.Monad.Except
 
 import GHC.TypeLits
 
-import Crypto.Cipher.Types
-
 
 type CryptoUUID (namespace :: Symbol) = CryptoID namespace UUID
 
@@ -76,13 +74,11 @@ encrypt :: forall a m namespace.
            , MonadError CryptoIDError m
            ) => CryptoIDKey -> a -> m (CryptoUUID namespace)
 encrypt key val = do
-  plaintext <- pad (blockSize cipher) . Lazy.ByteString.toStrict $ encode val
+  plaintext <- pad 16 . Lazy.ByteString.toStrict $ encode val
   
   mapCiphertext uuidConversion =<< Poly.encrypt key plaintext
     where
       uuidConversion = maybe (throwError CiphertextConversionFailed) return . fromByteString . Lazy.ByteString.fromStrict
-      cipher :: CryptoCipher
-      cipher = undefined
 
 
 -- | Decrypt an arbitrary serializable value