-- |
-- Module : Crypto.PubKey.Curve448
-- License : BSD-style
-- Maintainer : John Galt <jgalt@centromere.net>
-- Stability : experimental
-- Portability : unknown
--
-- Curve448 support
--
-- Internally uses Decaf point compression to omit the cofactor
-- and implementation by Mike Hamburg. Externally API and
-- data types are compatible with the encoding specified in RFC 7748.
--
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MagicHash #-}
module Crypto.PubKey.Curve448
( SecretKey
, PublicKey
, DhSecret
-- * Smart constructors
, dhSecret
, publicKey
, secretKey
-- * methods
, dh
, toPublic
, generateSecretKey
) where
import Data.Word
import Foreign.Ptr
import GHC.Ptr
import Crypto.Error
import Crypto.Random
import Crypto.Internal.Compat
import Crypto.Internal.Imports
import Crypto.Internal.ByteArray (ByteArrayAccess, ScrubbedBytes, Bytes, withByteArray)
import qualified Crypto.Internal.ByteArray as B
-- | A Curve448 Secret key
newtype SecretKey = SecretKey ScrubbedBytes
deriving (Show,Eq,ByteArrayAccess,NFData)
-- | A Curve448 public key
newtype PublicKey = PublicKey Bytes
deriving (Show,Eq,ByteArrayAccess,NFData)
-- | A Curve448 Diffie Hellman secret related to a
-- public key and a secret key.
newtype DhSecret = DhSecret ScrubbedBytes
deriving (Show,Eq,ByteArrayAccess,NFData)
-- | Try to build a public key from a bytearray
publicKey :: ByteArrayAccess bs => bs -> CryptoFailable PublicKey
publicKey bs
| B.length bs == x448_bytes = CryptoPassed $ PublicKey $ B.copyAndFreeze bs (\_ -> return ())
| otherwise = CryptoFailed CryptoError_PublicKeySizeInvalid
-- | Try to build a secret key from a bytearray
secretKey :: ByteArrayAccess bs => bs -> CryptoFailable SecretKey
secretKey bs
| B.length bs == x448_bytes = unsafeDoIO $
withByteArray bs $ \inp -> do
valid <- isValidPtr inp
if valid
then (CryptoPassed . SecretKey) <$> B.copy bs (\_ -> return ())
else return $ CryptoFailed CryptoError_SecretKeyStructureInvalid
| otherwise = CryptoFailed CryptoError_SecretKeySizeInvalid
where
isValidPtr :: Ptr Word8 -> IO Bool
isValidPtr _ =
return True
{-# NOINLINE secretKey #-}
-- | Create a DhSecret from a bytearray object
dhSecret :: ByteArrayAccess b => b -> CryptoFailable DhSecret
dhSecret bs
| B.length bs == x448_bytes = CryptoPassed $ DhSecret $ B.copyAndFreeze bs (\_ -> return ())
| otherwise = CryptoFailed CryptoError_SharedSecretSizeInvalid
-- | Compute the Diffie Hellman secret from a public key and a secret key.
--
-- This implementation may return an all-zero value as it does not check for
-- the condition.
dh :: PublicKey -> SecretKey -> DhSecret
dh (PublicKey pub) (SecretKey sec) = DhSecret <$>
B.allocAndFreeze x448_bytes $ \result ->
withByteArray sec $ \psec ->
withByteArray pub $ \ppub ->
decaf_x448 result ppub psec
{-# NOINLINE dh #-}
-- | Create a public key from a secret key
toPublic :: SecretKey -> PublicKey
toPublic (SecretKey sec) = PublicKey <$>
B.allocAndFreeze x448_bytes $ \result ->
withByteArray sec $ \psec ->
decaf_x448_derive_public_key result psec
{-# NOINLINE toPublic #-}
-- | Generate a secret key.
generateSecretKey :: MonadRandom m => m SecretKey
generateSecretKey = SecretKey <$> getRandomBytes x448_bytes
x448_bytes :: Int
x448_bytes = 448 `quot` 8
foreign import ccall "cryptonite_decaf_x448"
decaf_x448 :: Ptr Word8 -- ^ public
-> Ptr Word8 -- ^ basepoint
-> Ptr Word8 -- ^ secret
-> IO ()
foreign import ccall "cryptonite_decaf_x448_derive_public_key"
decaf_x448_derive_public_key :: Ptr Word8 -- ^ public
-> Ptr Word8 -- ^ secret
-> IO ()