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-- Copyright 2018 Google LLC
--
-- Licensed under the Apache License, Version 2.0 (the "License"); you may not
-- use this file except in compliance with the License. You may obtain a copy of
-- the License at
--
-- https://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-- WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-- License for the specific language governing permissions and limitations under
-- the License.
{-|
Module: Data.HMAC
Description: Hash-based message authentication codes
Copyright: 2018 Google LLC
License: Apache License, version 2.0
Hash-based message authentication codes (HMACs). An HMAC guarantees
authenticity but not confidentiality.
-}
module Data.HMAC
( -- * Computing HMACs
HMAC(HMAC)
, hmac
-- * Cryptographic hash algorithms
, Algorithm
, sha1
-- ** SHA-2 family
-- | The SHA-2 family of hash functions is defined in
-- [FIPS 180-4](https://csrc.nist.gov/publications/detail/fips/180/4/final).
, sha224, sha256, sha384, sha512
-- * Keys
, SecretKey(SecretKey)
-- * Error handling
, Error
-- * Legacy functions
, md5
) where
import Control.Monad.Trans.Class (lift)
import Control.Monad.Trans.Except (runExceptT)
import Data.ByteString (ByteString)
import qualified Data.ByteString.Lazy as Lazy (ByteString)
import qualified Data.ByteString.Lazy as ByteString.Lazy
import qualified Data.ByteString.Unsafe as ByteString
import Foreign.Marshal.Unsafe (unsafeLocalState)
import BTLS.BoringSSL.Base
import BTLS.BoringSSL.Digest (evpMaxMDSize)
import BTLS.BoringSSL.HMAC
import BTLS.BoringSSL.Mem (cryptoMemcmp)
import BTLS.Buffer (onBufferOfMaxSize)
import BTLS.Result (Error, check)
import BTLS.Types (Algorithm(Algorithm), SecretKey(SecretKey), showHex)
import Data.Digest (md5, sha1, sha224, sha256, sha384, sha512)
-- | A hash-based message authentication code. Equality comparisons on this type
-- are constant-time.
newtype HMAC = HMAC ByteString
instance Eq HMAC where
(HMAC a) == (HMAC b) =
unsafeLocalState $
ByteString.unsafeUseAsCStringLen a $ \(a', size) ->
ByteString.unsafeUseAsCStringLen b $ \(b', _) ->
(==0) <$> cryptoMemcmp a' b' size
instance Show HMAC where
show (HMAC m) = showHex m
-- | Creates an HMAC according to the given 'Algorithm'.
hmac :: Algorithm -> SecretKey -> Lazy.ByteString -> Either [Error] HMAC
hmac (Algorithm md) (SecretKey key) bytes =
unsafeLocalState $ runExceptT $ do
ctx <- lift mallocHMACCtx
check $ hmacInitEx ctx key md noEngine
lift $ mapM_ (hmacUpdate ctx) (ByteString.Lazy.toChunks bytes)
lift $ HMAC <$> onBufferOfMaxSize evpMaxMDSize (hmacFinal ctx)
|
