Codec.Crypto.HKDF: Add test 7 from RFC 5869

2 files changed, 7 insertions, 3 deletions

diff --git a/src/Codec/Crypto/HKDF.hs b/src/Codec/Crypto/HKDF.hs
index bb29ca6..8e81fd1 100644
--- a/src/Codec/Crypto/HKDF.hs
+++ b/src/Codec/Crypto/HKDF.hs
@@ -13,7 +13,7 @@
 -- the License.
 
 module Codec.Crypto.HKDF
-  ( Salt(Salt), SecretKey(SecretKey)
+  ( Salt(Salt), SecretKey(SecretKey), noSalt
   , extract
   ) where
 
@@ -27,7 +27,7 @@ import Unsafe.Coerce (unsafeCoerce)
 import Data.Digest.Internal (Algorithm(Algorithm))
 import Internal.Digest (evpMaxMDSize)
 import Internal.HKDF
-import Types (Salt(Salt), SecretKey(SecretKey))
+import Types (Salt(Salt), SecretKey(SecretKey), noSalt)
 
 -- | Computes an HKDF pseudorandom key (PRK) as specified by RFC 5869.
 extract :: Algorithm -> Salt -> SecretKey -> SecretKey
diff --git a/src/Types.hs b/src/Types.hs
index a625c3e..6b430c2 100644
--- a/src/Types.hs
+++ b/src/Types.hs
@@ -13,16 +13,20 @@
 -- the License.
 
 module Types
-  ( Salt(Salt)
+  ( Salt(Salt), noSalt
   , SecretKey(SecretKey)
   ) where
 
 import Data.ByteString (ByteString)
+import qualified Data.ByteString as ByteString
 
 -- | A salt. Equality comparisons on this type are variable-time.
 newtype Salt = Salt ByteString
   deriving (Eq, Ord, Show)
 
+noSalt :: Salt
+noSalt = Salt ByteString.empty
+
 -- | A secret key used as input to a cipher or HMAC. Equality comparisons on
 -- this type are variable-time.
 newtype SecretKey = SecretKey ByteString