diff --git a/Crypto/Random.hs b/Crypto/Random.hs
--- a/Crypto/Random.hs
+++ b/Crypto/Random.hs
@@ -36,7 +36,7 @@
 -- |many generators have these error conditions in common
 data GenError =
 	  GenErrorOther String	-- ^ Misc
-	| RequestedTooManyBytes	-- ^ Requested more bytes than a single pass can generate (ex: genBytes g i | i > 2^(2^32))
+	| RequestedTooManyBytes	-- ^ Requested more bytes than a single pass can generate (The maximum request is generator dependent)
 	| RangeInvalid		-- ^ When using @genInteger g (l,h)@ and @logBase 2 (h - l) > (maxBound :: Int)@.
 	| NeedReseed		-- ^ Some generators cease operation after too high a count without a reseed (ex: NIST SP 800-90)
 	| NotEnoughEntropy	-- ^ For instantiating new generators (or reseeding)
@@ -47,19 +47,37 @@
 --
 -- Minimum complete definition: `newGen`, `genSeedLength`, `genBytes`, `reseed`.
 class CryptoRandomGen g where
-	-- |Instantiate a new random bit generator
+	-- |Instantiate a new random bit generator.  The provided bytestring should
+	-- be of length >= genSeedLength.  If the bytestring is shorter
+	-- then the call may fail (suggested error: `NotEnoughEntropy`).  If the
+	-- bytestring is of sufficent length the call should always succeed.
 	newGen :: B.ByteString -> Either GenError g
 
 	-- |Length of input entropy necessary to instantiate or reseed a generator
 	genSeedLength :: Tagged g ByteLength
 
-	-- |Obtain random data using a generator
+	-- | @genBytes len g@ generates a random ByteString of length @len@ and new generator.
+	-- The "MonadCryptoRandom" package has routines useful for converting the ByteString
+	-- to commonly needed values (but "cereal" or other deserialization libraries would also work).
+	--
+	-- This routine can fail if the generator has gone too long without a reseed (usually this
+	-- is in the ball-park of 2^48 requests).  Suggested error in this cases is `NeedReseed`
 	genBytes	:: ByteLength -> g -> Either GenError (B.ByteString, g)
 
 	-- |@genBytesWithEntropy g i entropy@ generates @i@ random bytes and use the
 	-- additional input @entropy@ in the generation of the requested data to
 	-- increase the confidence our generated data is a secure random stream.
 	--
+	-- Some generators use @entropy@ to perturb the state of the generator, meaning:
+	--
+	-- @
+	--     (_,g2') <- genBytesWithEntropy len g1 ent
+	--     (_,g2 ) <- genBytes len g1
+	--     g2 /= g2'
+	-- @
+	--
+	-- But this is not required.
+	--
 	-- Default:
 	-- 
 	-- @
@@ -74,7 +92,10 @@
 				let entropy' = B.append entropy (B.replicate (len - B.length entropy) 0)
 				in Right (zwp' entropy' bs, g')
 
-	-- |reseed the generator
+	-- |If the generator has produced too many random bytes on its existing seed
+	-- it will throw `NeedReseed`.  In that case, reseed the generator using this function and
+	-- a new high-entropy seed of length >= `genSeedLength`.  Using bytestrings that are too short
+	-- can result in an error (`NotEnoughEntropy`).
 	reseed		:: B.ByteString -> g -> Either GenError g
 
 -- |Use "System.Crypto.Random" to obtain entropy for `newGen`.
diff --git a/crypto-api.cabal b/crypto-api.cabal
--- a/crypto-api.cabal
+++ b/crypto-api.cabal
@@ -1,5 +1,5 @@
 name:           crypto-api
-version:        0.2
+version:        0.2.1
 license:        BSD3
 license-file:   LICENSE
 copyright:      Thomas DuBuisson <thomas.dubuisson@gmail.com>, Dominic Steinitz (see Data.LargeWord module)
@@ -52,8 +52,7 @@
   Build-Depends: base == 4.*,
                  bytestring >= 0.9 && < 0.10,
                  cereal >= 0.2 && < 0.4,
-                 tagged == 0.1.*,
-                 filepath >= 1.1 && < 1.3
+                 tagged == 0.1.*
   ghc-options:   -O2
   hs-source-dirs:
   exposed-modules: Crypto.Classes, Crypto.Types, Crypto.HMAC, Data.LargeWord, Crypto.Modes, System.Crypto.Random, Crypto.Random, Crypto.Padding