89 lines
3.7 KiB
Haskell
89 lines
3.7 KiB
Haskell
-- | Examples of how to use @cryptonite@.
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module Crypto.Tutorial
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( -- * API design
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-- $api_design
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-- * Symmetric block ciphers
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-- $symmetric_block_ciphers
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) where
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-- $api_design
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--
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-- APIs in cryptonite are often based on type classes from package
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-- <https://hackage.haskell.org/package/memory memory>, notably
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-- 'Data.ByteArray.ByteArrayAccess' and 'Data.ByteArray.ByteArray'.
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-- Module "Data.ByteArray" provides many primitives that are useful to
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-- work with cryptonite types. For example function 'Data.ByteArray.convert'
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-- can transform one 'Data.ByteArray.ByteArrayAccess' concrete type like
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-- 'Crypto.Hash.Digest' to a 'Data.ByteString.ByteString'.
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--
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-- Algorithms and functions needing random bytes are based on type class
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-- 'Crypto.Random.Types.MonadRandom'. Implementation 'IO' uses a system source
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-- of entropy. It is also possible to use a 'Crypto.Random.Types.DRG' with
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-- 'Crypto.Random.Types.MonadPseudoRandom'
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--
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-- Error conditions are returned with data type 'Crypto.Error.CryptoFailable'.
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-- Functions in module "Crypto.Error" can convert those values to runtime
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-- exceptions, 'Maybe' or 'Either' values.
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-- $symmetric_block_ciphers
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--
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-- > {-# LANGUAGE OverloadedStrings #-}
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-- > {-# LANGUAGE ScopedTypeVariables #-}
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-- > {-# LANGUAGE GADTs #-}
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-- >
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-- > import Crypto.Cipher.AES (AES256)
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-- > import Crypto.Cipher.Types (BlockCipher(..), Cipher(..), nullIV, KeySizeSpecifier(..), IV, makeIV)
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-- > import Crypto.Error (CryptoFailable(..), CryptoError(..))
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-- >
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-- > import qualified Crypto.Random.Types as CRT
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-- >
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-- > import Data.ByteArray (ByteArray)
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-- > import Data.ByteString (ByteString)
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-- >
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-- > -- | Not required, but most general implementation
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-- > data Key c a where
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-- > Key :: (BlockCipher c, ByteArray a) => a -> Key c a
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-- >
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-- > -- | Generates a string of bytes (key) of a specific length for a given block cipher
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-- > genSecretKey :: forall m c a. (CRT.MonadRandom m, BlockCipher c, ByteArray a) => c -> Int -> m (Key c a)
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-- > genSecretKey _ = fmap Key . CRT.getRandomBytes
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-- >
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-- > -- | Generate a random initialization vector for a given block cipher
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-- > genRandomIV :: forall m c. (CRT.MonadRandom m, BlockCipher c) => c -> m (Maybe (IV c))
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-- > genRandomIV _ = do
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-- > bytes :: ByteString <- CRT.getRandomBytes $ blockSize (undefined :: c)
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-- > return $ makeIV bytes
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-- >
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-- > -- | Initialize a block cipher
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-- > initCipher :: (BlockCipher c, ByteArray a) => Key c a -> Either CryptoError c
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-- > initCipher (Key k) = case cipherInit k of
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-- > CryptoFailed e -> Left e
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-- > CryptoPassed a -> Right a
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-- >
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-- > encrypt :: (BlockCipher c, ByteArray a) => Key c a -> IV c -> a -> Either CryptoError a
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-- > encrypt secretKey initIV msg =
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-- > case initCipher secretKey of
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-- > Left e -> Left e
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-- > Right c -> Right $ ctrCombine c initIV msg
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-- >
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-- > decrypt :: (BlockCipher c, ByteArray a) => Key c a -> IV c -> a -> Either CryptoError a
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-- > decrypt = encrypt
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-- >
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-- > exampleAES256 :: ByteString -> IO ()
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-- > exampleAES256 msg = do
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-- > -- secret key needs 256 bits (32 * 8)
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-- > secretKey <- genSecretKey (undefined :: AES256) 32
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-- > mInitIV <- genRandomIV (undefined :: AES256)
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-- > case mInitIV of
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-- > Nothing -> error "Failed to generate and initialization vector."
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-- > Just initIV -> do
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-- > let encryptedMsg = encrypt secretKey initIV msg
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-- > decryptedMsg = decrypt secretKey initIV =<< encryptedMsg
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-- > case (,) <$> encryptedMsg <*> decryptedMsg of
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-- > Left err -> error $ show err
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-- > Right (eMsg, dMsg) -> do
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-- > putStrLn $ "Original Message: " ++ show msg
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-- > putStrLn $ "Message after encryption: " ++ show eMsg
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-- > putStrLn $ "Message after decryption: " ++ show dMsg
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