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-rw-r--r--src/Codec/Crypto/HKDF.hs29
-rw-r--r--src/Types.hs8
-rw-r--r--tests/Codec/Crypto/HKDFTests.hs29
3 files changed, 56 insertions, 10 deletions
diff --git a/src/Codec/Crypto/HKDF.hs b/src/Codec/Crypto/HKDF.hs
index 8e81fd1..1c1dbda 100644
--- a/src/Codec/Crypto/HKDF.hs
+++ b/src/Codec/Crypto/HKDF.hs
@@ -13,8 +13,8 @@
-- the License.
module Codec.Crypto.HKDF
- ( Salt(Salt), SecretKey(SecretKey), noSalt
- , extract
+ ( AssociatedData(AssociatedData), Salt(Salt), SecretKey(SecretKey), noSalt
+ , extract, expand
) where
import qualified Data.ByteString as ByteString
@@ -27,7 +27,8 @@ import Unsafe.Coerce (unsafeCoerce)
import Data.Digest.Internal (Algorithm(Algorithm))
import Internal.Digest (evpMaxMDSize)
import Internal.HKDF
-import Types (Salt(Salt), SecretKey(SecretKey), noSalt)
+import Types
+ (AssociatedData(AssociatedData), Salt(Salt), SecretKey(SecretKey), noSalt)
-- | Computes an HKDF pseudorandom key (PRK) as specified by RFC 5869.
extract :: Algorithm -> Salt -> SecretKey -> SecretKey
@@ -46,6 +47,22 @@ extract (Algorithm md) (Salt salt) (SecretKey secret) =
(asCUCharBuf pSalt) (fromIntegral saltLen)
outLen <- fromIntegral <$> peek pOutLen
SecretKey <$> ByteString.packCStringLen (pOutKey, outLen)
- where
- asCUCharBuf :: Ptr CChar -> Ptr CUChar
- asCUCharBuf = unsafeCoerce
+
+-- | Computes HKDF output key material (OKM) as specified by RFC 5869.
+expand :: Algorithm -> AssociatedData -> Int -> SecretKey -> SecretKey
+expand (Algorithm md) (AssociatedData info) outLen (SecretKey secret) =
+ unsafeLocalState $
+ allocaArray outLen $ \pOutKey -> do
+ -- @HKDF_expand@ won't mutate @secret@ or @info@, so the sharing inherent
+ -- in 'ByteString.unsafeUseAsCStringLen' is fine.
+ ByteString.unsafeUseAsCStringLen secret $ \(pSecret, secretLen) ->
+ ByteString.unsafeUseAsCStringLen info $ \(pInfo, infoLen) ->
+ hkdfExpand
+ (asCUCharBuf pOutKey) (fromIntegral outLen)
+ md
+ (asCUCharBuf pSecret) (fromIntegral secretLen)
+ (asCUCharBuf pInfo) (fromIntegral infoLen)
+ SecretKey <$> ByteString.packCStringLen (pOutKey, outLen)
+
+asCUCharBuf :: Ptr CChar -> Ptr CUChar
+asCUCharBuf = unsafeCoerce
diff --git a/src/Types.hs b/src/Types.hs
index 6b430c2..3c0f350 100644
--- a/src/Types.hs
+++ b/src/Types.hs
@@ -13,13 +13,19 @@
-- the License.
module Types
- ( Salt(Salt), noSalt
+ ( AssociatedData(AssociatedData)
+ , Salt(Salt), noSalt
, SecretKey(SecretKey)
) where
import Data.ByteString (ByteString)
import qualified Data.ByteString as ByteString
+-- | Context or application-specific information. Equality comparisons on this
+-- type are variable-time.
+newtype AssociatedData = AssociatedData ByteString
+ deriving (Eq, Ord, Show)
+
-- | A salt. Equality comparisons on this type are variable-time.
newtype Salt = Salt ByteString
deriving (Eq, Ord, Show)
diff --git a/tests/Codec/Crypto/HKDFTests.hs b/tests/Codec/Crypto/HKDFTests.hs
index 995518c..b3b2a28 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), noSalt)
+import Codec.Crypto.HKDF (AssociatedData(AssociatedData), Salt(Salt), SecretKey(SecretKey), noSalt)
import qualified Codec.Crypto.HKDF as HKDF
import Data.Digest (sha1, sha256)
@@ -36,41 +36,64 @@ testRFC5869 = testGroup "RFC 5869 examples"
sha256
(SecretKey $ ByteString.replicate 22 0x0b)
(Salt $ ByteString.pack [0x00 .. 0x0c])
+ (AssociatedData $ ByteString.pack [0xf0 .. 0xf9])
+ 42
(SecretKey $ hex "077709362c2e32df0ddc3f0dc47bba6390b6c73bb50f9c3122ec844ad7c2b3e5")
+ (SecretKey $ hex "3cb25f25faacd57a90434f64d0362f2a2d2d0a90cf1a5a4c5db02d56ecc4c5bf34007208d5b887185865")
, t "test case 2"
sha256
(SecretKey $ ByteString.pack [0x00 .. 0x4f])
(Salt $ ByteString.pack [0x60 .. 0xaf])
+ (AssociatedData $ ByteString.pack [0xb0 .. 0xff])
+ 82
(SecretKey $ hex "06a6b88c5853361a06104c9ceb35b45cef760014904671014a193f40c15fc244")
+ (SecretKey $ hex "b11e398dc80327a1c8e7f78c596a49344f012eda2d4efad8a050cc4c19afa97c59045a99cac7827271cb41c65e590e09da3275600c2f09b8367793a9aca3db71cc30c58179ec3e87c14c01d5c1f3434f1d87")
, t "test case 3"
sha256
(SecretKey $ ByteString.replicate 22 0x0b)
(Salt "")
+ (AssociatedData "")
+ 42
(SecretKey $ hex "19ef24a32c717b167f33a91d6f648bdf96596776afdb6377ac434c1c293ccb04")
+ (SecretKey $ hex "8da4e775a563c18f715f802a063c5a31b8a11f5c5ee1879ec3454e5f3c738d2d9d201395faa4b61a96c8")
, t "test case 4"
sha1
(SecretKey $ ByteString.replicate 11 0x0b)
(Salt $ ByteString.pack [0x00 .. 0x0c])
+ (AssociatedData $ ByteString.pack [0xf0 .. 0xf9])
+ 42
(SecretKey $ hex "9b6c18c432a7bf8f0e71c8eb88f4b30baa2ba243")
+ (SecretKey $ hex "085a01ea1b10f36933068b56efa5ad81a4f14b822f5b091568a9cdd4f155fda2c22e422478d305f3f896")
, t "test case 5"
sha1
(SecretKey $ ByteString.pack [0x00 .. 0x4f])
(Salt $ ByteString.pack [0x60 .. 0xaf])
+ (AssociatedData $ ByteString.pack [0xb0 .. 0xff])
+ 82
(SecretKey $ hex "8adae09a2a307059478d309b26c4115a224cfaf6")
+ (SecretKey $ hex "0bd770a74d1160f7c9f12cd5912a06ebff6adcae899d92191fe4305673ba2ffe8fa3f1a4e5ad79f3f334b3b202b2173c486ea37ce3d397ed034c7f9dfeb15c5e927336d0441f4c4300e2cff0d0900b52d3b4")
, t "test case 6"
sha1
(SecretKey $ ByteString.replicate 22 0x0b)
(Salt "")
+ (AssociatedData "")
+ 42
(SecretKey $ hex "da8c8a73c7fa77288ec6f5e7c297786aa0d32d01")
+ (SecretKey $ hex "0ac1af7002b3d761d1e55298da9d0506b9ae52057220a306e07b6b87e8df21d0ea00033de03984d34918")
, t "test case 7"
sha1
(SecretKey $ ByteString.replicate 22 0x0c)
noSalt
+ (AssociatedData "")
+ 42
(SecretKey $ hex "2adccada18779e7c2077ad2eb19d3f3e731385dd")
+ (SecretKey $ hex "2c91117204d745f3500d636a62f64f0ab3bae548aa53d423b0d1f27ebba6f5e5673a081d70cce7acfc48")
]
where
- t name hash ikm salt prk =
- testGroup name [testCase "extract" $ HKDF.extract hash salt ikm @?= prk]
+ t name hash ikm salt info len prk okm =
+ testGroup name [ testCase "extract" $ HKDF.extract hash salt ikm @?= prk
+ , testCase "expand" $ HKDF.expand hash info len prk @?= okm
+ ]
hex :: ByteString -> ByteString
hex s =