From a70d7fa4a478753e0ab765fb05559e1769760232 Mon Sep 17 00:00:00 2001
From: Benjamin Barenblat <bbaren@google.com>
Date: Thu, 2 Aug 2018 16:43:43 -0400
Subject: Codec.Crypto.HKDF: Add test 7 from RFC 5869

---
 src/Codec/Crypto/HKDF.hs        | 4 ++--
 src/Types.hs                    | 6 +++++-
 tests/Codec/Crypto/HKDFTests.hs | 7 ++++++-
 3 files changed, 13 insertions(+), 4 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
diff --git a/tests/Codec/Crypto/HKDFTests.hs b/tests/Codec/Crypto/HKDFTests.hs
index 5daffdb..995518c 100644
--- a/tests/Codec/Crypto/HKDFTests.hs
+++ b/tests/Codec/Crypto/HKDFTests.hs
@@ -23,7 +23,7 @@ import qualified Data.ByteString.Char8 as ByteString.Char8
 import Test.Tasty (TestTree, testGroup)
 import Test.Tasty.HUnit ((@?=), testCase)
 
-import Codec.Crypto.HKDF (Salt(Salt), SecretKey(SecretKey))
+import Codec.Crypto.HKDF (Salt(Salt), SecretKey(SecretKey), noSalt)
 import qualified Codec.Crypto.HKDF as HKDF
 import Data.Digest (sha1, sha256)
 
@@ -62,6 +62,11 @@ testRFC5869 = testGroup "RFC 5869 examples"
       (SecretKey $ ByteString.replicate 22 0x0b)
       (Salt "")
       (SecretKey $ hex "da8c8a73c7fa77288ec6f5e7c297786aa0d32d01")
+  , t "test case 7"
+      sha1
+      (SecretKey $ ByteString.replicate 22 0x0c)
+      noSalt
+      (SecretKey $ hex "2adccada18779e7c2077ad2eb19d3f3e731385dd")
   ]
   where
     t name hash ikm salt prk =
-- 
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