{-# LANGUAGE TypeFamilies #-}
module Crypto.Noise.Hash.SHA256
(
SHA256
) where
import qualified Crypto.Hash as H
import qualified Crypto.MAC.HMAC as M
import Data.ByteArray (ScrubbedBytes, convert, empty, snoc)
import Data.List (unfoldr)
import Data.Word (Word8)
import Crypto.Noise.Hash
data SHA256
instance Hash SHA256 where
newtype ChainingKey SHA256 = HCKSHA256 ScrubbedBytes
newtype Digest SHA256 = HDSHA256 (H.Digest H.SHA256)
hashName _ = "SHA256"
hashLength _ = 32
hash = hash'
hashHKDF = hkdf
hashBytesToCK = bytesToCK
hashCKToBytes = ckToBytes
hashToBytes = toBytes
hash' :: ScrubbedBytes -> Digest SHA256
hash' bs = HDSHA256 $ H.hash bs
hkdf :: ChainingKey SHA256
-> ScrubbedBytes
-> Word8
-> [ScrubbedBytes]
hkdf (HCKSHA256 ck) keyMat numOutputs = loop (empty, 1)
where
hmac key info = convert (M.hmac key info :: M.HMAC H.SHA256) :: ScrubbedBytes
tempKey = hmac ck keyMat
loop = unfoldr $ \(c, i) -> let r = hmac tempKey (c `snoc` i) in
if i == 0
then Nothing
else if i <= numOutputs
then Just (r, (r, i + 1))
else Nothing
bytesToCK :: ScrubbedBytes -> ChainingKey SHA256
bytesToCK = HCKSHA256
ckToBytes :: ChainingKey SHA256 -> ScrubbedBytes
ckToBytes (HCKSHA256 ck) = ck
toBytes :: Digest SHA256 -> ScrubbedBytes
toBytes (HDSHA256 d) = convert d