diff --git a/crypto-conduit.cabal b/crypto-conduit.cabal
--- a/crypto-conduit.cabal
+++ b/crypto-conduit.cabal
@@ -1,6 +1,6 @@
 Cabal-version:       >= 1.8
 Name:                crypto-conduit
-Version:             0.1
+Version:             0.1.1
 Synopsis:            Conduit interface for cryptographic operations (from crypto-api).
 Homepage:            https://github.com/meteficha/crypto-conduit
 License:             BSD3
@@ -32,7 +32,8 @@
     bytestring   >= 0.9 && < 0.10,
     cereal       >= 0.3 && < 0.4,
     crypto-api   >= 0.8 && < 0.9,
-    conduit      >= 0.0 && < 0.1
+    conduit      >= 0.0 && < 0.1,
+    transformers == 0.2.*
   GHC-options: -Wall
 
 Test-suite runtests
@@ -43,6 +44,7 @@
     cereal       >= 0.3 && < 0.4,
     crypto-api   >= 0.8 && < 0.9,
     conduit      >= 0.0 && < 0.1,
+    transformers == 0.2.*,
 
     cryptocipher == 0.3.*,
     cryptohash   == 0.7.*,
diff --git a/src/Crypto/Conduit.hs b/src/Crypto/Conduit.hs
--- a/src/Crypto/Conduit.hs
+++ b/src/Crypto/Conduit.hs
@@ -7,6 +7,7 @@
 module Crypto.Conduit
     ( -- * Cryptographic hash functions
       sinkHash
+    , hashFile
 
       -- * Hash-based message authentication code (HMAC)
     , sinkHmac
@@ -31,7 +32,7 @@
       -- ** Cipher-block chaining message authentication code (CBC-MAC)
     , sinkCbcMac
 
-      -- * Helpers
+      -- * Internal helpers
     , blocked
     , BlockMode(..)
     , Block(..)
@@ -60,8 +61,12 @@
 
 -- from conduit
 import Data.Conduit
+import Data.Conduit.Binary (sourceFile)
 
+-- from transformers
+import Control.Monad.IO.Class (MonadIO, liftIO)
 
+
 -- | Helper to get our return type.
 getType :: Monad m => sink input m output -> output
 getType = undefined
@@ -89,6 +94,17 @@
       blockSize = (C.blockLength .::. getType sink) `div` 8
 
 
+-- | Hashes the whole contents of the given file in constant
+-- memory.  This function is just a convenient wrapper around
+-- 'sinkHash' defined as:
+--
+-- @
+-- hashFile fp = 'liftIO' $ 'runResourceT' ('sourceFile' fp '$$' 'sinkHash')
+-- @
+hashFile :: (MonadIO m, C.Hash ctx d) => FilePath -> m d
+hashFile fp = liftIO $ runResourceT (sourceFile fp $$ sinkHash)
+
+
 ----------------------------------------------------------------------
 
 
@@ -307,10 +323,11 @@
 
 
 -- | A 'Sink' that computes the CBC-MAC of a stream of
--- 'B.ByteString'@s@ and creates a digest @d@.  Expects the input
--- length to be a multiple of the block size of the cipher and
--- fails otherwise.  (Note that CBC-MAC is not secure for
--- variable-length messages.)
+-- 'B.ByteString'@s@ and creates a digest (already encoded in a
+-- 'B.ByteString', since we're using a block cipher).  Expects
+-- the input length to be a multiple of the block size of the
+-- cipher and fails otherwise.  (Note that CBC-MAC is not secure
+-- for variable-length messages.)
 sinkCbcMac :: (Resource m, C.BlockCipher k) =>
               k -- ^ Cipher key.
            -> Sink B.ByteString m B.ByteString