Crypton.hs

-- Crypton.hs: shim for crypton
-- Copyright © 2016-2024  Clint Adams
-- This software is released under the terms of the Expat license.
-- (See the LICENSE file).
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE PackageImports #-}
{-# LANGUAGE UndecidableInstances #-}

module Codec.Encryption.OpenPGP.Internal.Crypton
    ( HOWrappedCCT (..)
    ) where

import Control.Error.Util (note)
import qualified Crypto.Error as CE
import Data.Bifunctor (bimap)
import qualified Data.ByteString as B
import qualified "crypton" Crypto.Cipher.Types as CCT

import Codec.Encryption.OpenPGP.Internal.HOBlockCipher

newtype HOWrappedCCT a
    = HWCCT a

instance CCT.BlockCipher cipher => HOBlockCipher (HOWrappedCCT cipher) where
    cipherInit = bimap show HWCCT . CE.eitherCryptoError . CCT.cipherInit
    cipherName (HWCCT c) = CCT.cipherName c
    cipherKeySize (HWCCT c) = CCT.cipherKeySize c
    blockSize (HWCCT c) = CCT.blockSize c
    cfbEncrypt (HWCCT c) iv bs =
        hammerIV iv >>= \i -> return (CCT.cfbEncrypt c i bs)
    cfbDecrypt (HWCCT c) iv bs =
        hammerIV iv >>= \i -> return (CCT.cfbDecrypt c i bs)

hammerIV
    :: CCT.BlockCipher cipher
    => B.ByteString -> Either String (CCT.IV cipher)
hammerIV = note "crypton bad IV" . CCT.makeIV